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victorbravo(at)sbcglobal.
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 Posted: Wed Jul 04, 2018 9:16 am Post subject: Firestar/HKS Engine Test Run |
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Greetings Kolbers,
Yesterday we finally were able to test run the HKS engine installation on my Firestar 2. The HKS engine started right up and ran, but it needed carburetor adjustment. I had a friend there who has experience with the HKS engine, and he was kind enough to adjust the carburetors using a dual vacuum gauge.
The one big issue I had was that the engine vibration was far far more than I was ever used to seeing on an aircraft. Part of this is that I'm "an airplane guy" instead of "an ultralight guy", Part of it is that the HKS is an opposed 2 cylinder engine with a very high compression ratio (11 to 1). But part of this is also that it did shake and vibrate a LOT, and I started thinking about how things tend to get loose and rattle apart in a high vibration environment.
The one thing that really worried me is that around idle speed something became resonant and the wing struts started to vibrate up and down in the middle, maybe half an inch up and hald an inch down versus a straight line. Aluminum does NOT like this kind of vibration! Neither do fasteners. After about two minutes we shut the engine down, and someone foun the wing strut attachment pin (the short clevis pin) on the ground next to the airplane. I had put the pin in place from above without the safety pin )ground runs only). The vibration backed the pin completely out!
Does anyone else have this kind of wing strut vibration with the Kolb?
Photos of the test run and adjustment wre posted here, scroll halfway down the page to to post # 952
http://www.homebuiltairplanes.com/forums/showthread.php?t=28504&page=64&p=433039#post433039
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
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neilsenrm(at)gmail.com
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| Posted: Wed Jul 04, 2018 11:04 am Post subject: Firestar/HKS Engine Test Run |
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Bill
I'm sure Larry will chime with his HKS knowledge.
You need to get over that airplane vs Ultralight thing. Vibrations are bad news. My redrive VW runs smoother at cruise RPMs than any GA airplane I have ever flown.
Most airplane engines have RPMs that you stay away from or pass through quickly. The HKS is known for its smoothness. I have to believe that what you have experienced is torsional resonance. Take the prop off and it will likely run smooth a silk. The higher the compression and fewer the cylinders the harder it is to tame. Geared engines are more prone to this issue but some direct drive/prop engines have issues also. Internal combustion engines will slow down on compression stroke and speed up on ignition stroke. A prop wants to turn a constant RPM. When a prop is subjected to these drastic changes in RPM (resonance) the prop blades will whip around and do nasty things and sometimes worse. All reduction drive engines have some form of dampening device to reduce this resonance but will likely not work sufficiently at all RPMs (normally have more issues at idle RPMs). It is also possible that engine/prop combination will not work.
Worth what you paid for it.
Rick Neilsen
Redrive VW Powered MKIIIC
On Wed, Jul 4, 2018 at 1:20 PM Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)> wrote:
| Quote: | Greetings Kolbers,
Yesterday we finally were able to test run the HKS engine installation on my Firestar 2. The HKS engine started right up and ran, but it needed carburetor adjustment. I had a friend there who has experience with the HKS engine, and he was kind enough to adjust the carburetors using a dual vacuum gauge.
The one big issue I had was that the engine vibration was far far more than I was ever used to seeing on an aircraft. Part of this is that I'm "an airplane guy" instead of "an ultralight guy", Part of it is that the HKS is an opposed 2 cylinder engine with a very high compression ratio (11 to 1). But part of this is also that it did shake and vibrate a LOT, and I started thinking about how things tend to get loose and rattle apart in a high vibration environment.
The one thing that really worried me is that around idle speed something became resonant and the wing struts started to vibrate up and down in the middle, maybe half an inch up and hald an inch down versus a straight line. Aluminum does NOT like this kind of vibration! Neither do fasteners. After about two minutes we shut the engine down, and someone foun the wing strut attachment pin (the short clevis pin) on the ground next to the airplane. I had put the pin in place from above without the safety pin )ground runs only). The vibration backed the pin completely out!
Does anyone else have this kind of wing strut vibration with the Kolb?
Photos of the test run and adjustment wre posted here, scroll halfway down the page to to post # 952
http://www.homebuiltairplanes.com/forums/showthread.php?t=28504&page=64&p=433039#post433039
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities |
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
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gdhelton(at)gmail.com
Guest
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| Posted: Wed Jul 04, 2018 1:16 pm Post subject: Firestar/HKS Engine Test Run |
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|
Well Bill, I guess you should have learned a valuable lesson about not only Kolbs but any aircraft. If you install a pin, safety it, period. If you put a bolt in, put nut on it and safety it. As far as the vibration goes, you’ve got a wide range on your idle setting. Don’t worry about the rpm so much as finding at sweet spot where it runs smoothest. Is all that stuff you’ve got lashed to the boom tube the muffler you’ve been telling us about? Whew, sometimes our best ideas an efforts just don’t seem to work out. I’ve been there before. I think that’s the tallest Kolb I’ve ever seen. I’m on the short side so I’d need a ladder just to get into the cockpit. Good luck!
George H.
Firestar FS100, Hirth 2702
14GDH
Mesick, Michigan
gdhelton(at)gmail.com (gdhelton(at)gmail.com)
Sent from my iPhone
On Jul 4, 2018, at 3:03 PM, Rick Neilsen <neilsenrm(at)gmail.com (neilsenrm(at)gmail.com)> wrote:
| Quote: | Bill
I'm sure Larry will chime with his HKS knowledge.
You need to get over that airplane vs Ultralight thing. Vibrations are bad news. My redrive VW runs smoother at cruise RPMs than any GA airplane I have ever flown.
Most airplane engines have RPMs that you stay away from or pass through quickly. The HKS is known for its smoothness. I have to believe that what you have experienced is torsional resonance. Take the prop off and it will likely run smooth a silk. The higher the compression and fewer the cylinders the harder it is to tame. Geared engines are more prone to this issue but some direct drive/prop engines have issues also. Internal combustion engines will slow down on compression stroke and speed up on ignition stroke. A prop wants to turn a constant RPM. When a prop is subjected to these drastic changes in RPM (resonance) the prop blades will whip around and do nasty things and sometimes worse. All reduction drive engines have some form of dampening device to reduce this resonance but will likely not work sufficiently at all RPMs (normally have more issues at idle RPMs). It is also possible that engine/prop combination will not work.
Worth what you paid for it.
Rick Neilsen
Redrive VW Powered MKIIIC
On Wed, Jul 4, 2018 at 1:20 PM Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)> wrote:
| Quote: | Greetings Kolbers,
Yesterday we finally were able to test run the HKS engine installation on my Firestar 2. The HKS engine started right up and ran, but it needed carburetor adjustment. I had a friend there who has experience with the HKS engine, and he was kind enough to adjust the carburetors using a dual vacuum gauge.
The one big issue I had was that the engine vibration was far far more than I was ever used to seeing on an aircraft. Part of this is that I'm "an airplane guy" instead of "an ultralight guy", Part of it is that the HKS is an opposed 2 cylinder engine with a very high compression ratio (11 to 1). But part of this is also that it did shake and vibrate a LOT, and I started thinking about how things tend to get loose and rattle apart in a high vibration environment.
The one thing that really worried me is that around idle speed something became resonant and the wing struts started to vibrate up and down in the middle, maybe half an inch up and hald an inch down versus a straight line. Aluminum does NOT like this kind of vibration! Neither do fasteners. After about two minutes we shut the engine down, and someone foun the wing strut attachment pin (the short clevis pin) on the ground next to the airplane. I had put the pin in place from above without the safety pin )ground runs only). The vibration backed the pin completely out!
Does anyone else have this kind of wing strut vibration with the Kolb?
Photos of the test run and adjustment wre posted here, scroll halfway down the page to to post # 952
http://www.homebuiltairplanes.com/forums/showthread.php?t=28504&page=64&p=433039#post433039
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities |
|
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
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ceengland7(at)gmail.com
Guest
|
| Posted: Wed Jul 04, 2018 1:43 pm Post subject: Firestar/HKS Engine Test Run |
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|
Hey Bill, in that HBA link, you mentioned 1/2" of runout on the prop. Did you check blade runout prior to engine start? That much runout by itself could shake the engine off the plane. A prop is a prop, UL or not, and if it isn't running true, with exactly the same pitch on all blades, you're going to get vibration.
Charlie
On Wed, Jul 4, 2018 at 4:15 PM, George Helton <gdhelton(at)gmail.com (gdhelton(at)gmail.com)> wrote:
| Quote: | Well Bill, I guess you should have learned a valuable lesson about not only Kolbs but any aircraft. If you install a pin, safety it, period. If you put a bolt in, put nut on it and safety it. As far as the vibration goes, you’ve got a wide range on your idle setting. Don’t worry about the rpm so much as finding at sweet spot where it runs smoothest. Is all that stuff you’ve got lashed to the boom tube the muffler you’ve been telling us about? Whew, sometimes our best ideas an efforts just don’t seem to work out. I’ve been there before. I think that’s the tallest Kolb I’ve ever seen. I’m on the short side so I’d need a ladder just to get into the cockpit. Good luck!
George H.
Firestar FS100, Hirth 2702
14GDH
Mesick, Michigan
gdhelton(at)gmail.com (gdhelton(at)gmail.com)
Sent from my iPhone
On Jul 4, 2018, at 3:03 PM, Rick Neilsen <neilsenrm(at)gmail.com (neilsenrm(at)gmail.com)> wrote:
| Quote: | Bill
I'm sure Larry will chime with his HKS knowledge.
You need to get over that airplane vs Ultralight thing. Vibrations are bad news. My redrive VW runs smoother at cruise RPMs than any GA airplane I have ever flown.
Most airplane engines have RPMs that you stay away from or pass through quickly. The HKS is known for its smoothness. I have to believe that what you have experienced is torsional resonance. Take the prop off and it will likely run smooth a silk. The higher the compression and fewer the cylinders the harder it is to tame. Geared engines are more prone to this issue but some direct drive/prop engines have issues also. Internal combustion engines will slow down on compression stroke and speed up on ignition stroke. A prop wants to turn a constant RPM. When a prop is subjected to these drastic changes in RPM (resonance) the prop blades will whip around and do nasty things and sometimes worse. All reduction drive engines have some form of dampening device to reduce this resonance but will likely not work sufficiently at all RPMs (normally have more issues at idle RPMs). It is also possible that engine/prop combination will not work.
Worth what you paid for it.
Rick Neilsen
Redrive VW Powered MKIIIC
On Wed, Jul 4, 2018 at 1:20 PM Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)> wrote:
| Quote: | Greetings Kolbers,
Yesterday we finally were able to test run the HKS engine installation on my Firestar 2. The HKS engine started right up and ran, but it needed carburetor adjustment. I had a friend there who has experience with the HKS engine, and he was kind enough to adjust the carburetors using a dual vacuum gauge.
The one big issue I had was that the engine vibration was far far more than I was ever used to seeing on an aircraft. Part of this is that I'm "an airplane guy" instead of "an ultralight guy", Part of it is that the HKS is an opposed 2 cylinder engine with a very high compression ratio (11 to 1). But part of this is also that it did shake and vibrate a LOT, and I started thinking about how things tend to get loose and rattle apart in a high vibration environment.
The one thing that really worried me is that around idle speed something became resonant and the wing struts started to vibrate up and down in the middle, maybe half an inch up and hald an inch down versus a straight line. Aluminum does NOT like this kind of vibration! Neither do fasteners. After about two minutes we shut the engine down, and someone foun the wing strut attachment pin (the short clevis pin) on the ground next to the airplane. I had put the pin in place from above without the safety pin )ground runs only). The vibration backed the pin completely out!
Does anyone else have this kind of wing strut vibration with the Kolb?
Photos of the test run and adjustment wre posted here, scroll halfway down the page to to post # 952
http://www.homebuiltairplanes.com/forums/showthread.php?t=28504&page=64&p=433039#post433039
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities |
|
|
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
|
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| Back to top |
|
|
victorbravo(at)sbcglobal.
Guest
|
| Posted: Wed Jul 04, 2018 2:34 pm Post subject: Firestar/HKS Engine Test Run |
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|
Thank you all for your input and opinions... I appreciate it.
All that brightly colored junk lashed to the boom tube is the big tow strap that we used to tie the airplane to the Jeep. The tow strap looked big enough to lift a Sherman tank !
The 4" diameter silver tube under the tailboom is that Swiss Muffler I was talking about. Put it in the "woulda - coulda - shoulda worked" category. Regardless, I do need some sort of muffler, and this one actually works about as good as the stock HKS system, it just doesn't make a "wow!" difference like I thought it would.
It is the tallest Kolb I've ever seen too... that was the big plan all along, to get the wing angle up high . Nothing was custom-built or scientifically researched about it... it's just a set of taller steel gear legs from the Kolb Slingshot, with 21 inch Desser bush tires. I'm not a tall guy by any means but I can get in and out OK. The trick is backing my butt up to the fuselage side, stepping on the tire, and hoisting myself up onto the side of the cockpit (longeron). It is a little easier than it looks. I WAS wondering if I was going to have to have a one rung rope ladder or step stool or toe strap or something to get in. Turns out I don't need it.
Using the bottom of the wing as the reference, the airplane sits up at an 18 degree angle of attack (deck angle actually) when on the wheels. It's even a little more when it's on those roller skates that I use to move it in and out of the hangar.
I will indeed check the propeller runout when I re-pitch it. It may be a moot point, there is apparently no adjustment that I can make to it. I do not believe the crankshaft is bent, and there is no visible damage to the propeller hub.
In my own defense, the wing pins were only in temporarily, to get the wings out of the way of the propeller. The aircraft was NOT going to fly or even taxi on that day.
I hope I'm not going to get any one upset or annoyed, but I have purchased a set of vortex generators for it, and those are going on ASAP. The VG's have now been shown to work well on the Kolb wing design, and several of the more experienced Kolbers seem to agree that they work as advertised. Because I have such a high grorund angle on mine, I would guess that my airplane would be even more prone to stalling on landing, doing the "Kolb Quit" maneuver. In order to get a 3 point landing I will probably have to pull the stick farther back than with other Kolbs, and wait a little longer before the tail comes all the way down. Which would put me at greater risk of that stall/drop. So the VG's will hopefully give me a little more margin while I am learning how to fly the airplane.
Bill Berle
--------------------------------------------
On Wed, 7/4/18, Charlie England <ceengland7(at)gmail.com> wrote:
Subject: Re: Firestar/HKS Engine Test Run
To: kolb-list(at)matronics.com
Date: Wednesday, July 4, 2018, 2:42 PM
Hey Bill,
in that HBA link, you mentioned 1/2" of runout on the
prop. Did you check blade runout prior to engine start? That
much runout by itself could shake the engine off the plane.
A prop is a prop, UL or not, and if it isn't running
true, with exactly the same pitch on all blades, you're
going to get vibration.
Charlie
On Wed, Jul 4, 2018 at 4:15
PM, George Helton <gdhelton(at)gmail.com>
wrote:
Well
Bill, I guess you should have learned a valuable lesson
about not only Kolbs but any aircraft. If you install a pin,
safety it, period. If you put a bolt in, put nut on it and
safety it. As far as the vibration goes, you’ve got a wide
range on your idle setting. Don’t worry about the rpm so
much as finding at sweet spot where it runs
smoothest. Is all that stuff you’ve got lashed to
the boom tube the muffler you’ve been telling us about?
Whew, sometimes our best ideas an efforts just don’t seem
to work out. I’ve been there before. I think that’s the
tallest Kolb I’ve ever seen. I’m on the short side so
I’d need a ladder just to get into the cockpit. Good
luck! George H.Firestar FS100, Hirth
270214GDH Mesick,
Michigan gdhelton(at)gmail.com
Sent
from my iPhone
On Jul 4, 2018, at
3:03 PM, Rick Neilsen <neilsenrm(at)gmail.com>
wrote:
Bill
I'm sure Larry will chime with
his HKS knowledge.
You need to get over that airplane
vs Ultralight thing. Vibrations are bad news. My redrive VW
runs smoother at cruise RPMs than any GA airplane I have
ever flown.
Most airplane engines have RPMs
that you stay away from or pass through quickly. The HKS is
known for its smoothness. I have to believe that what you
have experienced is torsional resonance. Take the prop off
and it will likely run smooth a silk. The higher the
compression and fewer the cylinders the harder it is to
tame. Geared engines are more prone to this issue but some
direct drive/prop engines have issues also. Internal
combustion engines will slow down on compression stroke and
speed up on ignition stroke. A prop wants to turn a constant
RPM. When a prop is subjected to these drastic changes in
RPM (resonance) the prop blades will whip around and do
nasty things and sometimes worse. All reduction drive
engines have some form of dampening device to reduce this
resonance but will likely not work sufficiently at all RPMs
(normally have more issues at idle RPMs). It is also
possible that engine/prop combination will not
work.
Worth what you paid for
it.
Rick NeilsenRedrive VW Powered
MKIIIC
On Wed, Jul
4, 2018 at 1:20 PM Bill Berle <victorbravo(at)sbcglobal.net>
wrote:
Greetings
Kolbers,
Yesterday we finally were able to test run the HKS engine
installation on my Firestar 2. The HKS engine started right
up and ran, but it needed carburetor adjustment. I had a
friend there who has experience with the HKS engine, and he
was kind enough to adjust the carburetors using a dual
vacuum gauge.
The one big issue I had was that the engine vibration was
far far more than I was ever used to seeing on an aircraft.
Part of this is that I'm "an airplane guy"
instead of "an ultralight guy", Part of it is that
the HKS is an opposed 2 cylinder engine with a very high
compression ratio (11 to 1). But part of this is also that
it did shake and vibrate a LOT, and I started thinking about
how things tend to get loose and rattle apart in a high
vibration environment.
The one thing that really worried me is that around idle
speed something became resonant and the wing struts started
to vibrate up and down in the middle, maybe half an inch up
and hald an inch down versus a straight line. Aluminum does
NOT like this kind of vibration! Neither do fasteners. After
about two minutes we shut the engine down, and someone foun
the wing strut attachment pin (the short clevis pin) on the
ground next to the airplane. I had put the pin in place from
above without the safety pin )ground runs only). The
vibration backed the pin completely out!
Does anyone else have this kind of wing strut vibration with
the Kolb?
Photos of the test run and adjustment wre posted here,
scroll halfway down the page to to post # 952
http://www.homebuiltairplanes.
com/forums/showthread.php?t= 28504&page=64&p=433039#
post433039
Bill Berle
www.ezflaphandle.com
- safety & performance upgrade for light aircraft
www.grantstar.net
- winning proposals for non-profit and for-profit
entities
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
|
|
|
| Back to top |
|
|
gdhelton(at)gmail.com
Guest
|
| Posted: Wed Jul 04, 2018 6:43 pm Post subject: Firestar/HKS Engine Test Run |
|
|
I put vg’s on my Firestar a year ago. I did the bottom of horizontal stabilizers and the wings. They work well.
George H.
Firestar FS100, Hirth 2702
14GDH
Mesick, Michigan
gdhelton(at)gmail.com
Sent from my iPhone
| Quote: | On Jul 4, 2018, at 6:34 PM, Bill Berle <victorbravo(at)sbcglobal.net> wrote:
Thank you all for your input and opinions... I appreciate it.
All that brightly colored junk lashed to the boom tube is the big tow strap that we used to tie the airplane to the Jeep. The tow strap looked big enough to lift a Sherman tank !
The 4" diameter silver tube under the tailboom is that Swiss Muffler I was talking about. Put it in the "woulda - coulda - shoulda worked" category. Regardless, I do need some sort of muffler, and this one actually works about as good as the stock HKS system, it just doesn't make a "wow!" difference like I thought it would.
It is the tallest Kolb I've ever seen too... that was the big plan all along, to get the wing angle up high . Nothing was custom-built or scientifically researched about it... it's just a set of taller steel gear legs from the Kolb Slingshot, with 21 inch Desser bush tires. I'm not a tall guy by any means but I can get in and out OK. The trick is backing my butt up to the fuselage side, stepping on the tire, and hoisting myself up onto the side of the cockpit (longeron). It is a little easier than it looks. I WAS wondering if I was going to have to have a one rung rope ladder or step stool or toe strap or something to get in. Turns out I don't need it.
Using the bottom of the wing as the reference, the airplane sits up at an 18 degree angle of attack (deck angle actually) when on the wheels. It's even a little more when it's on those roller skates that I use to move it in and out of the hangar.
I will indeed check the propeller runout when I re-pitch it. It may be a moot point, there is apparently no adjustment that I can make to it. I do not believe the crankshaft is bent, and there is no visible damage to the propeller hub.
In my own defense, the wing pins were only in temporarily, to get the wings out of the way of the propeller. The aircraft was NOT going to fly or even taxi on that day.
I hope I'm not going to get any one upset or annoyed, but I have purchased a set of vortex generators for it, and those are going on ASAP. The VG's have now been shown to work well on the Kolb wing design, and several of the more experienced Kolbers seem to agree that they work as advertised. Because I have such a high grorund angle on mine, I would guess that my airplane would be even more prone to stalling on landing, doing the "Kolb Quit" maneuver. In order to get a 3 point landing I will probably have to pull the stick farther back than with other Kolbs, and wait a little longer before the tail comes all the way down. Which would put me at greater risk of that stall/drop. So the VG's will hopefully give me a little more margin while I am learning how to fly the airplane.
Bill Berle
--------------------------------------------
On Wed, 7/4/18, Charlie England <ceengland7(at)gmail.com> wrote:
Subject: Re: Firestar/HKS Engine Test Run
To: kolb-list(at)matronics.com
Date: Wednesday, July 4, 2018, 2:42 PM
Hey Bill,
in that HBA link, you mentioned 1/2" of runout on the
prop. Did you check blade runout prior to engine start? That
much runout by itself could shake the engine off the plane.
A prop is a prop, UL or not, and if it isn't running
true, with exactly the same pitch on all blades, you're
going to get vibration.
Charlie
On Wed, Jul 4, 2018 at 4:15
PM, George Helton <gdhelton(at)gmail.com>
wrote:
Well
Bill, I guess you should have learned a valuable lesson
about not only Kolbs but any aircraft. If you install a pin,
safety it, period. If you put a bolt in, put nut on it and
safety it. As far as the vibration goes, you’ve got a wide
range on your idle setting. Don’t worry about the rpm so
much as finding at sweet spot where it runs
smoothest. Is all that stuff you’ve got lashed to
the boom tube the muffler you’ve been telling us about?
Whew, sometimes our best ideas an efforts just don’t seem
to work out. I’ve been there before. I think that’s the
tallest Kolb I’ve ever seen. I’m on the short side so
I’d need a ladder just to get into the cockpit. Good
luck! George H.Firestar FS100, Hirth
270214GDH Mesick,
Michigan gdhelton(at)gmail.com
Sent
from my iPhone
On Jul 4, 2018, at
3:03 PM, Rick Neilsen <neilsenrm(at)gmail.com>
wrote:
Bill
I'm sure Larry will chime with
his HKS knowledge.
You need to get over that airplane
vs Ultralight thing. Vibrations are bad news. My redrive VW
runs smoother at cruise RPMs than any GA airplane I have
ever flown.
Most airplane engines have RPMs
that you stay away from or pass through quickly. The HKS is
known for its smoothness. I have to believe that what you
have experienced is torsional resonance. Take the prop off
and it will likely run smooth a silk. The higher the
compression and fewer the cylinders the harder it is to
tame. Geared engines are more prone to this issue but some
direct drive/prop engines have issues also. Internal
combustion engines will slow down on compression stroke and
speed up on ignition stroke. A prop wants to turn a constant
RPM. When a prop is subjected to these drastic changes in
RPM (resonance) the prop blades will whip around and do
nasty things and sometimes worse. All reduction drive
engines have some form of dampening device to reduce this
resonance but will likely not work sufficiently at all RPMs
(normally have more issues at idle RPMs). It is also
possible that engine/prop combination will not
work.
Worth what you paid for
it.
Rick NeilsenRedrive VW Powered
MKIIIC
On Wed, Jul
4, 2018 at 1:20 PM Bill Berle <victorbravo(at)sbcglobal.net>
wrote:
Greetings
Kolbers,
Yesterday we finally were able to test run the HKS engine
installation on my Firestar 2. The HKS engine started right
up and ran, but it needed carburetor adjustment. I had a
friend there who has experience with the HKS engine, and he
was kind enough to adjust the carburetors using a dual
vacuum gauge.
The one big issue I had was that the engine vibration was
far far more than I was ever used to seeing on an aircraft.
Part of this is that I'm "an airplane guy"
instead of "an ultralight guy", Part of it is that
the HKS is an opposed 2 cylinder engine with a very high
compression ratio (11 to 1). But part of this is also that
it did shake and vibrate a LOT, and I started thinking about
how things tend to get loose and rattle apart in a high
vibration environment.
The one thing that really worried me is that around idle
speed something became resonant and the wing struts started
to vibrate up and down in the middle, maybe half an inch up
and hald an inch down versus a straight line. Aluminum does
NOT like this kind of vibration! Neither do fasteners. After
about two minutes we shut the engine down, and someone foun
the wing strut attachment pin (the short clevis pin) on the
ground next to the airplane. I had put the pin in place from
above without the safety pin )ground runs only). The
vibration backed the pin completely out!
Does anyone else have this kind of wing strut vibration with
the Kolb?
Photos of the test run and adjustment wre posted here,
scroll halfway down the page to to post # 952
http://www.homebuiltairplanes.
com/forums/showthread.php?t= 28504&page=64&p=433039#
post433039
Bill Berle
www.ezflaphandle.com
- safety & performance upgrade for light aircraft
www.grantstar.net
- winning proposals for non-profit and for-profit
entities
|
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Richard Pike
Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee
|
| Posted: Wed Jul 04, 2018 8:07 pm Post subject: Re: Firestar/HKS Engine Test Run |
|
|
Bill; thinking about what you said about torsional resonance, and looking back through your other posts on the homebuiltairplanes.com forum, I came upon your post on that list showing pictures of your exhaust system from May 2nd - http://www.homebuiltairplanes.com/forums/showthread.php?t=28504&page=57
Looking at your exhaust system (excellent workmanship, by the way - I am envious!) what I am seeing is two stainless tubes that are rigidly bolted to the heads and also rigidly bolted to the gearbox and which extend down about 18" before they attach to a flex coupling. Given that the engine is going to torsionally rock, the flex coupling at the end of those pipes is going to be moving from side to side at what I would think to be a significant amplitude (1/2"-1" ? More? Less?) with a frequency relative to RPM. And also very likely moving the lower pipe (which goes down to the muffler) from side to side in a similar fashion.
To put it another way, you have got a couple of steel pipes sticking out (at) 90 degrees for a foot and a a half out from your engine, waving them back and forth at 1,500-6,000 cycles per minute, with a weight attached to the end of them. That might not be a source of vibration, but from where I am standing it looks like a pretty good bet...
So how can you deal with it easily and as inexpensively as possible? I don't know how hard it would be to do, but I bet if you could add a flex coupling to each pipe immediately below their attachment to the gearbox, (which would put the flex coupling just barely below/almost in line with the motor mounts) a lot of your vibration would go away.
I am including your pictures from that list just to make things simple, hopefully someone on this list can expound on this a bit more.
And if I am all wrong on this, and the pipes are not moving as I would expect, then this post was worth what ya paid for it. (I miss Buford)
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_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
|
| Posted: Wed Jul 04, 2018 8:35 pm Post subject: Firestar/HKS Engine Test Run |
|
|
Bill, I've been flying in front of an HKS on my trike for 11 years. It does
not shake as you describe yours. Even when I first flew it with the carbs
significantly out of synch it was smooth. The only shaking it does is on
shutdown. Since you've already synched the carbs it should run like a
sewing machine. Sorry I can't tell you anything more than your engine is
not running properly.
I looked up the info I got from the HKS group.
" Jim Carruthers fabricated the exhaust system for my HKS when he did the
install on my Avid. *We contacted HKS in Japan about exhaust system
requirements and received a reply back from an HKS engineer. He said the
headers need to merge at 500mm for proper scavenging *and the length after
the merge was not critical though he noted that installations with
excessively long pipes after the merge had experienced rough idling issues.
As far as individual headers with no merge, there was an HKS on a Skyraider
at OshKosh years ago that had independent headers going to super trapp
mufflers. They had a difficult time getting the engine to run well and it
was way off on power. Jim routed my exhaust tubes to merge as close to
500mm as room would allow in the cowling and my engine runs fantastic.
Right after the merge he rolled a simple muffler can with no baffles and
its pretty quiet."
Hope this helps,
Rick
On Wed, Jul 4, 2018 at 9:43 PM, George Helton <gdhelton(at)gmail.com> wrote:
[quote]
I put vg’s on my Firestar a year ago. I did the bottom of horizontal
stabilizers and the wings. They work well.
George H.
Firestar FS100, Hirth 2702
14GDH
Mesick, Michigan
gdhelton(at)gmail.com
Sent from my iPhone
> On Jul 4, 2018, at 6:34 PM, Bill Berle <victorbravo(at)sbcglobal.net>
wrote:
>
>
>
> Thank you all for your input and opinions... I appreciate it.
>
> All that brightly colored junk lashed to the boom tube is the big tow
strap that we used to tie the airplane to the Jeep. The tow strap looked
big enough to lift a Sherman tank !
>
> The 4" diameter silver tube under the tailboom is that Swiss Muffler I
was talking about. Put it in the "woulda - coulda - shoulda worked"
category. Regardless, I do need some sort of muffler, and this one actually
works about as good as the stock HKS system, it just doesn't make a "wow!"
difference like I thought it would.
>
> It is the tallest Kolb I've ever seen too... that was the big plan all
along, to get the wing angle up high . Nothing was custom-built or
scientifically researched about it... it's just a set of taller steel gear
legs from the Kolb Slingshot, with 21 inch Desser bush tires. I'm not a
tall guy by any means but I can get in and out OK. The trick is backing my
butt up to the fuselage side, stepping on the tire, and hoisting myself up
onto the side of the cockpit (longeron). It is a little easier than it
looks. I WAS wondering if I was going to have to have a one rung rope
ladder or step stool or toe strap or something to get in. Turns out I don't
need it.
>
> Using the bottom of the wing as the reference, the airplane sits up at
an 18 degree angle of attack (deck angle actually) when on the wheels. It's
even a little more when it's on those roller skates that I use to move it
in and out of the hangar.
>
> I will indeed check the propeller runout when I re-pitch it. It may be a
moot point, there is apparently no adjustment that I can make to it. I do
not believe the crankshaft is bent, and there is no visible damage to the
propeller hub.
>
> In my own defense, the wing pins were only in temporarily, to get the
wings out of the way of the propeller. The aircraft was NOT going to fly or
even taxi on that day.
>
> I hope I'm not going to get any one upset or annoyed, but I have
purchased a set of vortex generators for it, and those are going on ASAP
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victorbravo(at)sbcglobal.
Guest
|
| Posted: Thu Jul 05, 2018 12:23 am Post subject: Firestar/HKS Engine Test Run |
|
|
Thank you guys again for putting your brains on this 
A year ago I had contacted Jerry Olenik at Green Sky (RIP Jerry), and he gave me a rough number of "something about 24 inches" between the exhaust flange and the merge. That is what we built. I had actually sent HKS Japan an e-mail and got no reply whatsoever (not even a rejection to my request for info). That was disappointing, and not 100% professional on their part.
The exhaust has a "restraining collar" bolted to the bolt that holds the tailboom tube to the fuselage at the back of the cage. This restraint is like a giant Adel clamp, except it has 1/8" gap around the exhaust pipe. The concept (per my aero engineer) is to prevent the exhaust from moving much or get into the prop, but to allow it to move a little so it can adjust itself in the muffler due to movement and heat expansion. This restraint is well below the flex joint, but before the pipe bends around the tailboom towards the muffler.
I have made arrangements to borrow a prop balancer, to at least eliminate that as the culprit. I'm also going to re-pitch the prop, at the same time as checking the runout. As mentioned, there's no runout adjustment on this prop, so it may be moot.
One other possibility for the runout is that as the prop blades pass near the exhaust and the rear of the cage, there is a "dead spot" or eddy current of air that allows that blade to see a little different in-flow or out-flow, resulting in THAT blade making a little less or more thrust at that instant, causing an aerodynamic fore-aft vibration (as opposed to a mass balance problem).
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities
--------------------------------------------
On Wed, 7/4/18, Richard Girard <aslsa.rng(at)gmail.com> wrote:
Subject: Re: Firestar/HKS Engine Test Run
To: "kolb-list(at)matronics.com" <kolb-list(at)matronics.com>
Date: Wednesday, July 4, 2018, 9:34 PM
Bill, I've been
flying in front of an HKS on my trike for 11 years. It does
not shake as you describe yours. Even when I first flew it
with the carbs significantly out of synch it was smooth. The
only shaking it does is on shutdown. Since you've
already synched the carbs it should run like a sewing
machine. Sorry I can't tell you anything more than your
engine is not running properly.I looked up the info I
got from the HKS group.
" Jim
Carruthers fabricated the exhaust system for my HKS when he
did the install on my Avid. We contacted HKS in Japan
about exhaust system requirements and received a reply back
from an HKS engineer. He said the headers need to merge at
500mm for proper scavenging and the length after the
merge was not critical though he noted that installations
with excessively long pipes after the merge had experienced
rough idling issues. As far as individual headers with no
merge, there was an HKS on a Skyraider at OshKosh years ago
that had independent headers going to super trapp mufflers.
They had a difficult time getting the engine to run well and
it was way off on power. Jim routed my exhaust tubes to
merge as close to 500mm as room would allow in the cowling
and my engine runs fantastic. Right after the merge he
rolled a simple muffler can with no baffles and its pretty
quiet."
Hope this
helps,Rick
On Wed, Jul 4, 2018 at
9:43 PM, George Helton <gdhelton(at)gmail.com>
wrote:
George Helton <gdhelton(at)gmail.com>
I put vg’s on my Firestar a year ago. I did the bottom of
horizontal stabilizers and the wings. They work well.
George H.
Firestar FS100, Hirth 2702
14GDH
Mesick, Michigan
gdhelton(at)gmail.com
Sent from my iPhone
> On Jul 4,
2018, at 6:34 PM, Bill Berle <victorbravo(at)sbcglobal.net>
wrote:
>
>
>
> Thank you all for your input and opinions... I
appreciate it.
>
> All that brightly colored junk lashed to the boom tube
is the big tow strap that we used to tie the airplane to the
Jeep. The tow strap looked big enough to lift a Sherman tank
!
>
> The 4" diameter silver tube under the tailboom is
that Swiss Muffler I was talking about. Put it in the
"woulda - coulda - shoulda worked" category.
Regardless, I do need some sort of muffler, and this one
actually works about as good as the stock HKS system, it
just doesn't make a "wow!" difference like I
thought it would.
>
> It is the tallest Kolb I've ever seen too... that
was the big plan all along, to get the wing angle up high .
Nothing was custom-built or scientifically researched about
it... it's just a set of taller steel gear legs from the
Kolb Slingshot, with 21 inch Desser bush tires. I'm
not a tall guy by any means but I can get in and out OK. The
trick is backing my butt up to the fuselage side, stepping
on the tire, and hoisting myself up onto the side of the
cockpit (longeron). It is a little easier than it looks. I
WAS wondering if I was going to have to have a one rung rope
ladder or step stool or toe strap or something to get in.
Turns out I don't need it.
>
> Using the bottom of the wing as the reference, the
airplane sits up at an 18 degree angle of attack (deck angle
actually) when on the wheels. It's even a little more
when it's on those roller skates that I use to move it
in and out of the hangar.
>
> I will indeed check the propeller runout when I
re-pitch it. It may be a moot point, there is apparently no
adjustment that I can make to it. I do not believe the
crankshaft is bent, and there is no visible damage to the
propeller hub.
>
> In my own defense, the wing pins were only in
temporarily, to get the wings out of the way of the
propeller. The aircraft was NOT going to fly or even taxi on
that day.
>
> I hope I'm not going to get any one upset or
annoyed, but I have purchased a set of vortex generators for
it, and those are going on ASAP. The VG's have now
been shown to work well on the Kolb wing design, and several
of the more experienced Kolbers seem to agree that they work
as advertised. Because I have such a high grorund angle on
mine, I would guess that my airplane would be even more
prone to stalling on landing, doing the "Kolb
Quit" maneuver. In order to get a 3 point landing I
will probably have to pull the stick farther back than with
other Kolbs, and wait a little longer before the tail comes
all the way down. Which would put me at greater risk of
that stall/drop. So the VG's will hopefully give me a
little more margin while I am learning how to fly the
airplane.
>
> Bill Berle
>
>
> ------------------------------ --------------
> On Wed, 7/4/18, Charlie England <ceengland7(at)gmail.com>
wrote:
>
> Subject: Re: Firestar/HKS Engine Test Run
> To: kolb-list(at)matronics.com
> Date: Wednesday, July 4, 2018, 2:42 PM
>
> Hey Bill,
> in that HBA link, you mentioned 1/2" of runout on
the
> prop. Did you check blade runout prior to engine start?
That
> much runout by itself could shake the engine off the
plane.
> A prop is a prop, UL or not, and if it isn't
running
> true, with exactly the same pitch on all blades,
you're
> going to get vibration.
> Charlie
> On Wed, Jul 4, 2018 at 4:15
> PM, George Helton <gdhelton(at)gmail.com>
> wrote:
> Well
> Bill, I guess you should have learned a valuable
lesson
> about not only Kolbs but any aircraft. If you install a
pin,
> safety it, period. If you put a bolt in, put nut on it
and
> safety it. As far as the vibration goes, you’ve got a
wide
> range on your idle setting. Don’t worry about the rpm
so
> much as finding at sweet spot where it runs
> smoothest. Is all that stuff you’ve got lashed to
> the boom tube the muffler you’ve been telling us
about?
> Whew, sometimes our best ideas an efforts just don’t
seem
> to work out. I’ve been there before. I think that’s
the
> tallest Kolb I’ve ever seen. I’m on the short side
so
> I’d need a ladder just to get into the cockpit. Good
> luck! George H.Firestar FS100, Hirth
> 270214GDH Mesick,
> Michigan gdhelton(at)gmail.com
>
> Sent
> from my iPhone
> On Jul 4, 2018, at
> 3:03 PM, Rick Neilsen <neilsenrm(at)gmail.com>
> wrote:
>
> Bill
> I'm sure Larry will chime with
> his HKS knowledge.
> You need to get over that airplane
> vs Ultralight thing. Vibrations are bad news. My
redrive VW
> runs smoother at cruise RPMs than any GA airplane I
have
> ever flown.
> Most airplane engines have RPMs
> that you stay away from or pass through quickly. The
HKS is
> known for its smoothness. I have to believe that what
you
> have experienced is torsional resonance. Take the prop
off
> and it will likely run smooth a silk. The higher the
> compression and fewer the cylinders the harder it is
to
> tame. Geared engines are more prone to this issue but
some
> direct drive/prop engines have issues also.
Internal
> combustion engines will slow down on compression stroke
and
> speed up on ignition stroke. A prop wants to turn a
constant
> RPM. When a prop is subjected to these drastic changes
in
> RPM (resonance) the prop blades will whip around and
do
> nasty things and sometimes worse. All reduction drive
> engines have some form of dampening device to reduce
this
> resonance but will likely not work sufficiently at all
RPMs
> (normally have more issues at idle RPMs). It is also
> possible that engine/prop combination will not
> work.
> Worth what you paid for
> it.
> Rick NeilsenRedrive VW Powered
> MKIIIC
> On Wed, Jul
> 4, 2018 at 1:20 PM Bill Berle <victorbravo(at)sbcglobal.net>
> wrote:
> Greetings
> Kolbers,
>
>
>
> Yesterday we finally were able to test run the HKS
engine
> installation on my Firestar 2. The HKS engine started
right
> up and ran, but it needed carburetor adjustment. I had
a
> friend there who has experience with the HKS engine,
and he
> was kind enough to adjust the carburetors using a dual
> vacuum gauge.
>
>
>
> The one big issue I had was that the engine vibration
was
> far far more than I was ever used to seeing on an
aircraft.
> Part of this is that I'm "an airplane
guy"
> instead of "an ultralight guy", Part of it is
that
> the HKS is an opposed 2 cylinder engine with a very
high
> compression ratio (11 to 1). But part of this is also
that
> it did shake and vibrate a LOT, and I started thinking
about
> how things tend to get loose and rattle apart in a
high
> vibration environment.
>
>
>
> The one thing that really worried me is that around
idle
> speed something became resonant and the wing struts
started
> to vibrate up and down in the middle, maybe half an
inch up
> and hald an inch down versus a straight line. Aluminum
does
> NOT like this kind of vibration! Neither do fasteners.
After
> about two minutes we shut the engine down, and someone
foun
> the wing strut attachment pin (the short clevis pin) on
the
> ground next to the airplane. I had put the pin in place
from
> above without the safety pin )ground runs only). The
> vibration backed the pin completely out!
>
>
>
> Does anyone else have this kind of wing strut vibration
with
> the Kolb?
>
>
>
> Photos of the test run and adjustment wre posted here,
> scroll halfway down the page to to post # 952
>
>
>
> http://www.homebuiltairplanes.
> com/forums/showthread.php?t=
28504&page=64&p=433039#
> post433039
>
>
>
> Bill Berle
>
> www.ezflaphandle.com
> - safety & performance upgrade for light aircraft
>
> www.grantstar.net
> - winning proposals for non-profit and
for-profit
> entities
>
>
>
>
>
>
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zeprep251(at)aol.com
Guest
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| Posted: Thu Jul 05, 2018 5:01 am Post subject: Firestar/HKS Engine Test Run |
|
|
just as an aside on your exhaust system,any exhaust that exits near the tube will travel along it and be drawn into the rear of the tube and blow into the cockpit like someone is back there with a leaf blower.I had to fashion a foam rubber plug to seal off the air flow up the tube, 6” thick with slits for the cables.The vg’s are the way to go, even with my MK3C short spring steel gear legs,the tail wheel touches down first when I’m solo. G.Aman MK3C Jabiru 2200A 1060hrs | Quote: | On Jul 5, 2018, at 4:23 AM, Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)> wrote:
--> Kolb-List message posted by: Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)>Thank you guys again for putting your brains on this A year ago I had contacted Jerry Olenik at Green Sky (RIP Jerry), and he gave me a rough number of "something about 24 inches" between the exhaust flange and the merge. That is what we built. I had actually sent HKS Japan an e-mail and got no reply whatsoever (not even a rejection to my request for info). That was disappointing, and not 100% professional on their part.The exhaust has a "restraining collar" bolted to the bolt that holds the tailboom tube to the fuselage at the back of the cage. This restraint is like a giant Adel clamp, except it has 1/8" gap around the exhaust pipe. The concept (per my aero engineer) is to prevent the exhaust from moving much or get into the prop, but to allow it to move a little so it can adjust itself in the muffler due to movement and heat expansion. This restraint is well below the flex joint, but before the pipe bends around the tailboom towards the muffler.I have made arrangements to borrow a prop balancer, to at least eliminate that as the culprit. I'm also going to re-pitch the prop, at the same time as checking the runout. As mentioned, there's no runout adjustment on this prop, so it may be moot.One other possibility for the runout is that as the prop blades pass near the exhaust and the rear of the cage, there is a "dead spot" or eddy current of air that allows that blade to see a little different in-flow or out-flow, resulting in THAT blade making a little less or more thrust at that instant, causing an aerodynamic fore-aft vibration (as opposed to a mass balance problem).Bill Berleaslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:Subject: Re: Firestar/HKS Engine Test RunTo: "kolb-list(at)matronics.com (kolb-list(at)matronics.com)" <kolb-list(at)matronics.com (kolb-list(at)matronics.com)>Date: Wednesday, July 4, 2018, 9:34 PMBill, I've beenflying in front of an HKS on my trike for 11 years. It doesnot shake as you describe yours. Even when I first flew itwith the carbs significantly out of synch it was smooth. Theonly shaking it does is on shutdown. Since you'vealready synched the carbs it should run like a sewingmachine. Sorry I can't tell you anything more than yourengine is not running properly.I looked up the info Igot from the HKS group." JimCarruthers fabricated the exhaust system for my HKS when hedid the install on my Avid. We contacted HKS in Japanabout exhaust system requirements and received a reply backfrom an HKS engineer. He said the headers need to merge at500mm for proper scavenging and the length after themerge was not critical though he noted that installationswith excessively long pipes after the merge had experiencedrough idling issues. As far as individual headers with nomerge, there was an HKS on a Skyraider at OshKosh years agothat had independent headers going to super trapp mufflers.They had a difficult time getting the engine to run well andit was way off on power. Jim routed my exhaust tubes tomerge as close to 500mm as room would allow in the cowlingand my engine runs fantastic. Right after the merge herolled a simple muffler can with no baffles and its prettyquiet."Hope thishelps,RickOn Wed, Jul 4, 2018 at9:43 PM, George Helton <gdhelton(at)gmail.com (gdhelton(at)gmail.com)>wrote:--> Kolb-List message posted by:George Helton <gdhelton(at)gmail.com (gdhelton(at)gmail.com)>I put vg’s on my Firestar a year ago. I did the bottom ofhorizontal stabilizers and the wings. They work well.George H. Firestar FS100, Hirth 270214GDHMesick, Michigan gdhelton(at)gmail.com (gdhelton(at)gmail.com)Sent from my iPhone2018, at 6:34 PM, Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)>wrote: | Quote: | | Thank you all for your input and opinions... I |
appreciate it. | Quote: | | All that brightly colored junk lashed to the boom tube |
is the big tow strap that we used to tie the airplane to theJeep. The tow strap looked big enough to lift a Sherman tank! | Quote: | | The 4" diameter silver tube under the tailboom is |
that Swiss Muffler I was talking about. Put it in the"woulda - coulda - shoulda worked" category.Regardless, I do need some sort of muffler, and this oneactually works about as good as the stock HKS system, itjust doesn't make a "wow!" difference like Ithought it would. | Quote: | | It is the tallest Kolb I've ever seen too... that |
was the big plan all along, to get the wing angle up high .Nothing was custom-built or scientifically researched aboutit... it's just a set of taller steel gear legs from theKolb Slingshot, with 21 inch Desser bush tires. I'mnot a tall guy by any means but I can get in and out OK. Thetrick is backing my butt up to the fuselage side, steppingon the tire, and hoisting myself up onto the side of thecockpit (longeron). It is a little easier than it looks. IWAS wondering if I was going to have to have a one rung ropeladder or step stool or toe strap or something to get in.Turns out I don't need it. | Quote: | | Using the bottom of the wing as the reference, the |
airplane sits up at an 18 degree angle of attack (deck angleactually) when on the wheels. It's even a little morewhen it's on those roller skates that I use to move itin and out of the hangar. | Quote: | | I will indeed check the propeller runout when I |
re-pitch it. It may be a moot point, there is apparently noadjustment that I can make to it. I do not believe thecrankshaft is bent, and there is no visible damage to thepropeller hub. | Quote: | | In my own defense, the wing pins were only in |
temporarily, to get the wings out of the way of thepropeller. The aircraft was NOT going to fly or even taxi onthat day. | Quote: | | I hope I'm not going to get any one upset or |
annoyed, but I have purchased a set of vortex generators forit, and those are going on ASAP. The VG's have nowbeen shown to work well on the Kolb wing design, and severalof the more experienced Kolbers seem to agree that they workas advertised. Because I have such a high grorund angle onmine, I would guess that my airplane would be even moreprone to stalling on landing, doing the "KolbQuit" maneuver. In order to get a 3 point landing Iwill probably have to pull the stick farther back than withother Kolbs, and wait a little longer before the tail comesall the way down. Which would put me at greater risk ofthat stall/drop. So the VG's will hopefully give me alittle more margin while I am learning how to fly theairplane. | Quote: | | ------------------------------ -------------- |
wrote: | Quote: | | Subject: Re: Firestar/HKS Engine Test Run |
| Quote: | | Date: Wednesday, July 4, 2018, 2:42 PM |
| Quote: | | in that HBA link, you mentioned 1/2" of runout on |
the | Quote: | | prop. Did you check blade runout prior to engine start? |
That | Quote: | | much runout by itself could shake the engine off the |
plane. | Quote: | | A prop is a prop, UL or not, and if it isn't |
running | Quote: | | true, with exactly the same pitch on all blades, |
you're | Quote: | | going to get vibration. |
| Quote: | | On Wed, Jul 4, 2018 at 4:15 |
| Quote: | | Bill, I guess you should have learned a valuable |
lesson | Quote: | | about not only Kolbs but any aircraft. If you install a |
pin, | Quote: | | safety it, period. If you put a bolt in, put nut on it |
and | Quote: | | safety it. As far as the vibration goes, you’ve got a |
wide | Quote: | | range on your idle setting. Don’t worry about the rpm |
so | Quote: | | much as finding at sweet spot where it runs |
| Quote: | | smoothest. Is all that stuff you’ve got lashed to |
| Quote: | | the boom tube the muffler you’ve been telling us |
about? | Quote: | | Whew, sometimes our best ideas an efforts just don’t |
seem | Quote: | | to work out. I’ve been there before. I think that’s |
the | Quote: | | tallest Kolb I’ve ever seen. I’m on the short side |
so | Quote: | | I’d need a ladder just to get into the cockpit. Good |
| Quote: | | luck! George H.Firestar FS100, Hirth |
| Quote: | | On Jul 4, 2018, at |
| Quote: | | I'm sure Larry will chime with |
| Quote: | | his HKS knowledge. |
| Quote: | | You need to get over that airplane |
| Quote: | | vs Ultralight thing. Vibrations are bad news. My |
redrive VW | Quote: | | runs smoother at cruise RPMs than any GA airplane I |
have | Quote: | | Most airplane engines have RPMs |
| Quote: | | that you stay away from or pass through quickly. The |
HKS is | Quote: | | known for its smoothness. I have to believe that what |
you | Quote: | | have experienced is torsional resonance. Take the prop |
off | Quote: | | and it will likely run smooth a silk. The higher the |
| Quote: | | compression and fewer the cylinders the harder it is |
to | Quote: | | tame. Geared engines are more prone to this issue but |
some | Quote: | | direct drive/prop engines have issues also. |
Internal | Quote: | | combustion engines will slow down on compression stroke |
and | Quote: | | speed up on ignition stroke. A prop wants to turn a |
constant | Quote: | | RPM. When a prop is subjected to these drastic changes |
in | Quote: | | RPM (resonance) the prop blades will whip around and |
do | Quote: | | nasty things and sometimes worse. All reduction drive |
| Quote: | | engines have some form of dampening device to reduce |
this | Quote: | | resonance but will likely not work sufficiently at all |
RPMs | Quote: | | (normally have more issues at idle RPMs). It is also |
| Quote: | | possible that engine/prop combination will not |
| Quote: | | Worth what you paid for |
| Quote: | | Rick NeilsenRedrive VW Powered |
| Quote: | | Yesterday we finally were able to test run the HKS |
engine | Quote: | | installation on my Firestar 2. The HKS engine started |
right | Quote: | | up and ran, but it needed carburetor adjustment. I had |
a | Quote: | | friend there who has experience with the HKS engine, |
and he | Quote: | | was kind enough to adjust the carburetors using a dual |
| Quote: | | The one big issue I had was that the engine vibration |
was | Quote: | | far far more than I was ever used to seeing on an |
aircraft. | Quote: | | Part of this is that I'm "an airplane |
guy" | Quote: | | instead of "an ultralight guy", Part of it is |
that | Quote: | | the HKS is an opposed 2 cylinder engine with a very |
high | Quote: | | compression ratio (11 to 1). But part of this is also |
that | Quote: | | it did shake and vibrate a LOT, and I started thinking |
about | Quote: | | how things tend to get loose and rattle apart in a |
high | Quote: | | vibration environment. |
| Quote: | | The one thing that really worried me is that around |
idle | Quote: | | speed something became resonant and the wing struts |
started | Quote: | | to vibrate up and down in the middle, maybe half an |
inch up | Quote: | | and hald an inch down versus a straight line. Aluminum |
does | Quote: | | NOT like this kind of vibration! Neither do fasteners. |
After | Quote: | | about two minutes we shut the engine down, and someone |
foun | Quote: | | the wing strut attachment pin (the short clevis pin) on |
the | Quote: | | ground next to the airplane. I had put the pin in place |
from | Quote: | | above without the safety pin )ground runs only). The |
| Quote: | | vibration backed the pin completely out! |
| Quote: | | Does anyone else have this kind of wing strut vibration |
with | Quote: | | Photos of the test run and adjustment wre posted here, |
| Quote: | | scroll halfway down the page to to post # 952 |
| Quote: | | com/forums/showthread.php?t= |
28504&page=64&p=433039# | Quote: | | - safety & performance upgrade for light aircraft |
| Quote: | | - winning proposals for non-profit and |
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ceengland7(at)gmail.com
Guest
|
| Posted: Thu Jul 05, 2018 5:22 am Post subject: Firestar/HKS Engine Test Run |
|
|
I've not had a runout adjustment feature on any prop I've ever used, but with heavier homebuilts running Lycs & Conts, the SOP is to measure tracking, and shim between the engine's prop flange and the prop's mating surface to get equal tracking. Often, a strip of typing paper around the bolt circle arc on one side is enough to move the tip close to 1/8". I don't recall your prop brand/model, but if you're seeing 1/2" of static runout on a prop with a machined hub and blades made in molds, you could have either a defective prop, or a bent flange. On the other hand, if it's just out that much while running, it could just be balance, or unequal pitch among the blades, or slight runout made worse by running the engine.
Static balance of the prop is a good first step, and relatively easy to do. Dynamic balance is better if you can beg/borrow a balancer, but if static balance and tracking are not right, the dynamic balancer may not be able to help you.
Pusher props do see weird airflow; that's one reason fast pushers (VariEze, etc) don't have quite the speed gains over tractor designs that the calculations would suggest. But I've never heard of it causing such drastic prop oscillations.
Charlie
On Thu, Jul 5, 2018 at 3:23 AM, Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)> wrote:
| Quote: | --> Kolb-List message posted by: Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)>
Thank you guys again for putting your brains on this
A year ago I had contacted Jerry Olenik at Green Sky (RIP Jerry), and he gave me a rough number of "something about 24 inches" between the exhaust flange and the merge. That is what we built. I had actually sent HKS Japan an e-mail and got no reply whatsoever (not even a rejection to my request for info). That was disappointing, and not 100% professional on their part.
The exhaust has a "restraining collar" bolted to the bolt that holds the tailboom tube to the fuselage at the back of the cage. This restraint is like a giant Adel clamp, except it has 1/8" gap around the exhaust pipe. The concept (per my aero engineer) is to prevent the exhaust from moving much or get into the prop, but to allow it to move a little so it can adjust itself in the muffler due to movement and heat expansion. This restraint is well below the flex joint, but before the pipe bends around the tailboom towards the muffler.
I have made arrangements to borrow a prop balancer, to at least eliminate that as the culprit. I'm also going to re-pitch the prop, at the same time as checking the runout. As mentioned, there's no runout adjustment on this prop, so it may be moot.
One other possibility for the runout is that as the prop blades pass near the exhaust and the rear of the cage, there is a "dead spot" or eddy current of air that allows that blade to see a little different in-flow or out-flow, resulting in THAT blade making a little less or more thrust at that instant, causing an aerodynamic fore-aft vibration (as opposed to a mass balance problem).
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities
--------------------------------------------
On Wed, 7/4/18, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
Subject: Re: Firestar/HKS Engine Test Run
To: "kolb-list(at)matronics.com (kolb-list(at)matronics.com)" <kolb-list(at)matronics.com (kolb-list(at)matronics.com)>
Date: Wednesday, July 4, 2018, 9:34 PM
Bill, I've been
flying in front of an HKS on my trike for 11 years. It does
not shake as you describe yours. Even when I first flew it
with the carbs significantly out of synch it was smooth. The
only shaking it does is on shutdown. Since you've
already synched the carbs it should run like a sewing
machine. Sorry I can't tell you anything more than your
engine is not running properly.I looked up the info I
got from the HKS group.
" Jim
Carruthers fabricated the exhaust system for my HKS when he
did the install on my Avid. We contacted HKS in Japan
about exhaust system requirements and received a reply back
from an HKS engineer. He said the headers need to merge at
500mm for proper scavenging and the length after the
merge was not critical though he noted that installations
with excessively long pipes after the merge had experienced
rough idling issues. As far as individual headers with no
merge, there was an HKS on a Skyraider at OshKosh years ago
that had independent headers going to super trapp mufflers.
They had a difficult time getting the engine to run well and
it was way off on power. Jim routed my exhaust tubes to
merge as close to 500mm as room would allow in the cowling
and my engine runs fantastic. Right after the merge he
rolled a simple muffler can with no baffles and its pretty
quiet."
Hope this
helps,Rick
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John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
|
| Posted: Thu Jul 05, 2018 7:40 am Post subject: Firestar/HKS Engine Test Run |
|
|
Bill/Kolbers:
Just a guess. Your exhaust system design is probably causing the vibration and the engine mounts are not able to absorb them, thus transmitting then to the airframe. With what little I know of your Kolb, I’d say it is a combination of unconventional exhaust and engine mounts.
My philosophy is KISS (keep it simple stupid). Your exhaust system goes way beyond KISS.
If it can be disconnected at the “Y” it might be a good idea to do that. Then test the engine isolated from all that exhaust plumbing.
I believe everyone has given you good advice.
I’m guessing you are trying to silence the HKS with the fancy exhaust. I think you must remember that the prop makes much more noise than the engine. So...when it is all over and done, when your engine is silenced, you still have to contend with the whiny prop noise, a trade more of ultralights.
I doubt the exhaust pipe in front of the prop is creating enough dead space to cause rough running. Kolbs have a lot more in front of the prop than just a small exhaust pipe.
Just my early morning thoughts. Take it for what it is worth.
High speed, low drag! 
John h
Atlanta, GA
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_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama |
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John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
|
| Posted: Thu Jul 05, 2018 7:44 am Post subject: Firestar/HKS Engine Test Run |
|
|
Gary:
Good info and remainder on carbon monoxide. You are absolutely correct, the tail boom is a leaf blower directed into the cockpit.
Don’t take a chance on CO2 poisoning.
John h
Atlanta, GA
From: owner-kolb-list-server(at)matronics.com [mailto:owner-kolb-list-server(at)matronics.com] On Behalf Of Gary Aman
Sent: Thursday, July 5, 2018 8:01 AM
To: kolb-list(at)matronics.com
Subject: Re: Firestar/HKS Engine Test Run
just as an aside on your exhaust system,any exhaust that exits near the tube will travel along it and be drawn into the rear of the tube and blow into the cockpit like someone is back there with a leaf blower.I had to fashion a foam rubber plug to seal off the air flow up the tube, 6” thick with slits for the cables.The vg’s are the way to go, even with my MK3C short spring steel gear legs,the tail wheel touches down first when I’m solo.
G.Aman MK3C Jabiru 2200A 1060hrs | Quote: |
On Jul 5, 2018, at 4:23 AM, Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)> wrote:
--> Kolb-List message posted by: Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)>
Thank you guys again for putting your brains on this
A year ago I had contacted Jerry Olenik at Green Sky (RIP Jerry), and he gave me a rough number of "something about 24 inches" between the exhaust flange and the merge. That is what we built. I had actually sent HKS Japan an e-mail and got no reply whatsoever (not even a rejection to my request for info). That was disappointing, and not 100% professional on their part.
The exhaust has a "restraining collar" bolted to the bolt that holds the tailboom tube to the fuselage at the back of the cage. This restraint is like a giant Adel clamp, except it has 1/8" gap around the exhaust pipe. The concept (per my aero engineer) is to prevent the exhaust from moving much or get into the prop, but to allow it to move a little so it can adjust itself in the muffler due to movement and heat expansion. This restraint is well below the flex joint, but before the pipe bends around the tailboom towards the muffler.
I have made arrangements to borrow a prop balancer, to at least eliminate that as the culprit. I'm also going to re-pitch the prop, at the same time as checking the runout. As mentioned, there's no runout adjustment on this prop, so it may be moot.
One other possibility for the runout is that as the prop blades pass near the exhaust and the rear of the cage, there is a "dead spot" or eddy current of air that allows that blade to see a little different in-flow or out-flow, resulting in THAT blade making a little less or more thrust at that instant, causing an aerodynamic fore-aft vibration (as opposed to a mass balance problem).
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities
--------------------------------------------
On Wed, 7/4/18, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
Subject: Re: Firestar/HKS Engine Test Run
To: "kolb-list(at)matronics.com (kolb-list(at)matronics.com)" <kolb-list(at)matronics.com (kolb-list(at)matronics.com)>
Date: Wednesday, July 4, 2018, 9:34 PM
Bill, I've been
flying in front of an HKS on my trike for 11 years. It does
not shake as you describe yours. Even when I first flew it
with the carbs significantly out of synch it was smooth. The
only shaking it does is on shutdown. Since you've
already synched the carbs it should run like a sewing
machine. Sorry I can't tell you anything more than your
engine is not running properly.I looked up the info I
got from the HKS group.
" Jim
Carruthers fabricated the exhaust system for my HKS when he
did the install on my Avid. We contacted HKS in Japan
about exhaust system requirements and received a reply back
from an HKS engineer. He said the headers need to merge at
500mm for proper scavenging and the length after the
merge was not critical though he noted that installations
with excessively long pipes after the merge had experienced
rough idling issues. As far as individual headers with no
merge, there was an HKS on a Skyraider at OshKosh years ago
that had independent headers going to super trapp mufflers.
They had a difficult time getting the engine to run well and
it was way off on power. Jim routed my exhaust tubes to
merge as close to 500mm as room would allow in the cowling
and my engine runs fantastic. Right after the merge he
rolled a simple muffler can with no baffles and its pretty
quiet."
Hope this
helps,Rick
On Wed, Jul 4, 2018 at
9:43 PM, George Helton <gdhelton(at)gmail.com (gdhelton(at)gmail.com)>
wrote:
--> Kolb-List message posted by:
George Helton <gdhelton(at)gmail.com (gdhelton(at)gmail.com)>
I put vg’s on my Firestar a year ago. I did the bottom of
horizontal stabilizers and the wings. They work well.
George H.
Firestar FS100, Hirth 2702
14GDH
Mesick, Michigan
gdhelton(at)gmail.com (gdhelton(at)gmail.com)
Sent from my iPhone
On Jul 4,
2018, at 6:34 PM, Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)>
wrote:
--> Kolb-List message posted by: Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)>
Thank you all for your input and opinions... I
appreciate it.
All that brightly colored junk lashed to the boom tube
is the big tow strap that we used to tie the airplane to the
Jeep. The tow strap looked big enough to lift a Sherman tank
!
The 4" diameter silver tube under the tailboom is
that Swiss Muffler I was talking about. Put it in the
"woulda - coulda - shoulda worked" category.
Regardless, I do need some sort of muffler, and this one
actually works about as good as the stock HKS system, it
just doesn't make a "wow!" difference like I
thought it would.
It is the tallest Kolb I've ever seen too... that
was the big plan all along, to get the wing angle up high .
Nothing was custom-built or scientifically researched about
it... it's just a set of taller steel gear legs from the
Kolb Slingshot, with 21 inch Desser bush tires. I'm
not a tall guy by any means but I can get in and out OK. The
trick is backing my butt up to the fuselage side, stepping
on the tire, and hoisting myself up onto the side of the
cockpit (longeron). It is a little easier than it looks. I
WAS wondering if I was going to have to have a one rung rope
ladder or step stool or toe strap or something to get in.
Turns out I don't need it.
Using the bottom of the wing as the reference, the
airplane sits up at an 18 degree angle of attack (deck angle
actually) when on the wheels. It's even a little more
when it's on those roller skates that I use to move it
in and out of the hangar.
I will indeed check the propeller runout when I
re-pitch it. It may be a moot point, there is apparently no
adjustment that I can make to it. I do not believe the
crankshaft is bent, and there is no visible damage to the
propeller hub.
In my own defense, the wing pins were only in
temporarily, to get the wings out of the way of the
propeller. The aircraft was NOT going to fly or even taxi on
that day.
I hope I'm not going to get any one upset or
annoyed, but I have purchased a set of vortex generators for
it, and those are going on ASAP. The VG's have now
been shown to work well on the Kolb wing design, and several
of the more experienced Kolbers seem to agree that they work
as advertised. Because I have such a high grorund angle on
mine, I would guess that my airplane would be even more
prone to stalling on landing, doing the "Kolb
Quit" maneuver. In order to get a 3 point landing I
will probably have to pull the stick farther back than with
other Kolbs, and wait a little longer before the tail comes
all the way down. Which would put me at greater risk of
that stall/drop. So the VG's will hopefully give me a
little more margin while I am learning how to fly the
airplane.
Bill Berle
------------------------------ --------------
On Wed, 7/4/18, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)>
wrote:
Subject: Re: Firestar/HKS Engine Test Run
To: kolb-list(at)matronics.com (kolb-list(at)matronics.com)
Date: Wednesday, July 4, 2018, 2:42 PM
Hey Bill,
in that HBA link, you mentioned 1/2" of runout on
the
prop. Did you check blade runout prior to engine start?
That
much runout by itself could shake the engine off the
plane.
A prop is a prop, UL or not, and if it isn't
running
true, with exactly the same pitch on all blades,
you're
going to get vibration.
Charlie
On Wed, Jul 4, 2018 at 4:15
PM, George Helton <gdhelton(at)gmail.com (gdhelton(at)gmail.com)>
wrote:
Well
Bill, I guess you should have learned a valuable
lesson
about not only Kolbs but any aircraft. If you install a
pin,
safety it, period. If you put a bolt in, put nut on it
and
safety it. As far as the vibration goes, you’ve got a
wide
range on your idle setting. Don’t worry about the rpm
so
much as finding at sweet spot where it runs
smoothest. Is all that stuff you’ve got lashed to
the boom tube the muffler you’ve been telling us
about?
Whew, sometimes our best ideas an efforts just don’t
seem
to work out. I’ve been there before. I think that’s
the
tallest Kolb I’ve ever seen. I’m on the short side
so
I’d need a ladder just to get into the cockpit. Good
luck! George H.Firestar FS100, Hirth
270214GDH Mesick,
Michigan gdhelton(at)gmail.com (gdhelton(at)gmail.com)
Sent
from my iPhone
On Jul 4, 2018, at
3:03 PM, Rick Neilsen <neilsenrm(at)gmail.com (neilsenrm(at)gmail.com)>
wrote:
Bill
I'm sure Larry will chime with
his HKS knowledge.
You need to get over that airplane
vs Ultralight thing. Vibrations are bad news. My
redrive VW
runs smoother at cruise RPMs than any GA airplane I
have
ever flown.
Most airplane engines have RPMs
that you stay away from or pass through quickly. The
HKS is
known for its smoothness. I have to believe that what
you
have experienced is torsional resonance. Take the prop
off
and it will likely run smooth a silk. The higher the
compression and fewer the cylinders the harder it is
to
tame. Geared engines are more prone to this issue but
some
direct drive/prop engines have issues also.
Internal
combustion engines will slow down on compression stroke
and
speed up on ignition stroke. A prop wants to turn a
constant
RPM. When a prop is subjected to these drastic changes
in
RPM (resonance) the prop blades will whip around and
do
nasty things and sometimes worse. All reduction drive
engines have some form of dampening device to reduce
this
resonance but will likely not work sufficiently at all
RPMs
(normally have more issues at idle RPMs). It is also
possible that engine/prop combination will not
work.
Worth what you paid for
it.
Rick NeilsenRedrive VW Powered
MKIIIC
On Wed, Jul
4, 2018 at 1:20 PM Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)>
wrote:
Greetings
Kolbers,
Yesterday we finally were able to test run the HKS
engine
installation on my Firestar 2. The HKS engine started
right
up and ran, but it needed carburetor adjustment. I had
a
friend there who has experience with the HKS engine,
and he
was kind enough to adjust the carburetors using a dual
vacuum gauge.
The one big issue I had was that the engine vibration
was
far far more than I was ever used to seeing on an
aircraft.
Part of this is that I'm "an airplane
guy"
instead of "an ultralight guy", Part of it is
that
the HKS is an opposed 2 cylinder engine with a very
high
compression ratio (11 to 1). But part of this is also
that
it did shake and vibrate a LOT, and I started thinking
about
how things tend to get loose and rattle apart in a
high
vibration environment.
The one thing that really worried me is that around
idle
speed something became resonant and the wing struts
started
to vibrate up and down in the middle, maybe half an
inch up
and hald an inch down versus a straight line. Aluminum
does
NOT like this kind of vibration! Neither do fasteners.
After
about two minutes we shut the engine down, and someone
foun
the wing strut attachment pin (the short clevis pin) on
the
ground next to the airplane. I had put the pin in place
from
above without the safety pin )ground runs only). The
vibration backed the pin completely out!
Does anyone else have this kind of wing strut vibration
with
the Kolb?
Photos of the test run and adjustment wre posted here,
scroll halfway down the page to to post # 952
http://www.homebuiltairplanes.
com/forums/showthread.php?t=
28504&page=64&p=433039#
post433039
Bill Berle
www.ezflaphandle.com
- safety & performance upgrade for light aircraft
www.grantstar.net
- winning proposals for non-profit and
for-profit
entities
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John Hauck
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hauck's holler
Titus, Alabama |
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John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
|
| Posted: Thu Jul 05, 2018 7:44 am Post subject: Firestar/HKS Engine Test Run |
|
|
Charlie:
Used track wooden props on my US and FS with bond paper shims.
Never needed to shim the WARP Drive props. They seem to be true or within 1/16” when they come from the factory.
John h
Atlanta, GA
From: owner-kolb-list-server(at)matronics.com [mailto:owner-kolb-list-server(at)matronics.com] On Behalf Of Charlie England
Sent: Thursday, July 5, 2018 8:13 AM
To: kolb-list(at)matronics.com
Subject: Re: Firestar/HKS Engine Test Run
I've not had a runout adjustment feature on any prop I've ever used, but with heavier homebuilts running Lycs & Conts, the SOP is to measure tracking, and shim between the engine's prop flange and the prop's mating surface to get equal tracking. Often, a strip of typing paper around the bolt circle arc on one side is enough to move the tip close to 1/8". I don't recall your prop bran witd/model, but if you're seeing 1/2" of static runout on a prop with a machined hub and blades made in molds, you could have either a defective prop, or a bent flange. On the other hand, if it's just out that much while running, it could just be balance, or unequal pitch among the blades, or slight runout made worse by running the engine.
Static balance of the prop is a good first step, and relatively easy to do. Dynamic balance is better if you can beg/borrow a balancer, but if static balance and tracking are not right, the dynamic balancer may not be able to help you.
Pusher props do see weird airflow; that's one reason fast pushers (VariEze, etc) don't have quite the speed gains over tractor designs that the calculations would suggest. But I've never heard of it causing such drastic prop oscillations.
Charlie
On Thu, Jul 5, 2018 at 3:23 AM, Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)> wrote:
--> Kolb-List message posted by: Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)>
Thank you guys again for putting your brains on this
A year ago I had contacted Jerry Olenik at Green Sky (RIP Jerry), and he gave me a rough number of "something about 24 inches" between the exhaust flange and the merge. That is what we built. I had actually sent HKS Japan an e-mail and got no reply whatsoever (not even a rejection to my request for info). That was disappointing, and not 100% professional on their part.
The exhaust has a "restraining collar" bolted to the bolt that holds the tailboom tube to the fuselage at the back of the cage. This restraint is like a giant Adel clamp, except it has 1/8" gap around the exhaust pipe. The concept (per my aero engineer) is to prevent the exhaust from moving much or get into the prop, but to allow it to move a little so it can adjust itself in the muffler due to movement and heat expansion. This restraint is well below the flex joint, but before the pipe bends around the tailboom towards the muffler.
I have made arrangements to borrow a prop balancer, to at least eliminate that as the culprit. I'm also going to re-pitch the prop, at the same time as checking the runout. As mentioned, there's no runout adjustment on this prop, so it may be moot.
One other possibility for the runout is that as the prop blades pass near the exhaust and the rear of the cage, there is a "dead spot" or eddy current of air that allows that blade to see a little different in-flow or out-flow, resulting in THAT blade making a little less or more thrust at that instant, causing an aerodynamic fore-aft vibration (as opposed to a mass balance problem).
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities
--------------------------------------------
On Wed, 7/4/18, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
Subject: Re: Firestar/HKS Engine Test Run
To: "kolb-list(at)matronics.com (kolb-list(at)matronics.com)" <kolb-list(at)matronics.com (kolb-list(at)matronics.com)>
Date: Wednesday, July 4, 2018, 9:34 PM
Bill, I've been
flying in front of an HKS on my trike for 11 years. It does
not shake as you describe yours. Even when I first flew it
with the carbs significantly out of synch it was smooth. The
only shaking it does is on shutdown. Since you've
already synched the carbs it should run like a sewing
machine. Sorry I can't tell you anything more than your
engine is not running properly.I looked up the info I
got from the HKS group.
" Jim
Carruthers fabricated the exhaust system for my HKS when he
did the install on my Avid. We contacted HKS in Japan
about exhaust system requirements and received a reply back
from an HKS engineer. He said the headers need to merge at
500mm for proper scavenging and the length after the
merge was not critical though he noted that installations
with excessively long pipes after the merge had experienced
rough idling issues. As far as individual headers with no
merge, there was an HKS on a Skyraider at OshKosh years ago
that had independent headers going to super trapp mufflers.
They had a difficult time getting the engine to run well and
it was way off on power. Jim routed my exhaust tubes to
merge as close to 500mm as room would allow in the cowling
and my engine runs fantastic. Right after the merge he
rolled a simple muffler can with no baffles and its pretty
quiet."
Hope this
helps,Rick
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_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama |
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ceengland7(at)gmail.com
Guest
|
| Posted: Thu Jul 05, 2018 9:02 am Post subject: Firestar/HKS Engine Test Run |
|
|
I agree; there's no reason for a Warp Drive or similar design with 'made in a mold' blades and a machined hub to have any runout, unless it's defective, or the drive's prop flange is bent.
Charlie
On 7/5/2018 10:44 AM, John Hauck wrote:
| Quote: | <![endif]--> <![endif]-->
Charlie:
Used track wooden props on my US and FS with bond paper shims.
Never needed to shim the WARP Drive props. They seem to be true or within 1/16” when they come from the factory.
John h
Atlanta, GA
From: owner-kolb-list-server(at)matronics.com (owner-kolb-list-server(at)matronics.com) [mailto:owner-kolb-list-server(at)matronics.com (owner-kolb-list-server(at)matronics.com)] On Behalf Of Charlie England
Sent: Thursday, July 5, 2018 8:13 AM
To: kolb-list(at)matronics.com (kolb-list(at)matronics.com)
Subject: Re: Firestar/HKS Engine Test Run
I've not had a runout adjustment feature on any prop I've ever used, but with heavier homebuilts running Lycs & Conts, the SOP is to measure tracking, and shim between the engine's prop flange and the prop's mating surface to get equal tracking. Often, a strip of typing paper around the bolt circle arc on one side is enough to move the tip close to 1/8". I don't recall your prop bran witd/model, but if you're seeing 1/2" of static runout on a prop with a machined hub and blades made in molds, you could have either a defective prop, or a bent flange. On the other hand, if it's just out that much while running, it could just be balance, or unequal pitch among the blades, or slight runout made worse by running the engine.
Static balance of the prop is a good first step, and relatively easy to do. Dynamic balance is better if you can beg/borrow a balancer, but if static balance and tracking are not right, the dynamic balancer may not be able to help you.
Pusher props do see weird airflow; that's one reason fast pushers (VariEze, etc) don't have quite the speed gains over tractor designs that the calculations would suggest. But I've never heard of it causing such drastic prop oscillations.
Charlie
On Thu, Jul 5, 2018 at 3:23 AM, Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)> wrote:
--> Kolb-List message posted by: Bill Berle <victorbravo(at)sbcglobal.net (victorbravo(at)sbcglobal.net)>
Thank you guys again for putting your brains on this
A year ago I had contacted Jerry Olenik at Green Sky (RIP Jerry), and he gave me a rough number of "something about 24 inches" between the exhaust flange and the merge. That is what we built. I had actually sent HKS Japan an e-mail and got no reply whatsoever (not even a rejection to my request for info). That was disappointing, and not 100% professional on their part.
The exhaust has a "restraining collar" bolted to the bolt that holds the tailboom tube to the fuselage at the back of the cage. This restraint is like a giant Adel clamp, except it has 1/8" gap around the exhaust pipe. The concept (per my aero engineer) is to prevent the exhaust from moving much or get into the prop, but to allow it to move a little so it can adjust itself in the muffler due to movement and heat expansion. This restraint is well below the flex joint, but before the pipe bends around the tailboom towards the muffler.
I have made arrangements to borrow a prop balancer, to at least eliminate that as the culprit. I'm also going to re-pitch the prop, at the same time as checking the runout. As mentioned, there's no runout adjustment on this prop, so it may be moot.
One other possibility for the runout is that as the prop blades pass near the exhaust and the rear of the cage, there is a "dead spot" or eddy current of air that allows that blade to see a little different in-flow or out-flow, resulting in THAT blade making a little less or more thrust at that instant, causing an aerodynamic fore-aft vibration (as opposed to a mass balance problem).
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities
--------------------------------------------
On Wed, 7/4/18, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
Subject: Re: Firestar/HKS Engine Test Run
To: "kolb-list(at)matronics.com (kolb-list(at)matronics.com)" <kolb-list(at)matronics.com (kolb-list(at)matronics.com)>
Date: Wednesday, July 4, 2018, 9:34 PM
Bill, I've been
flying in front of an HKS on my trike for 11 years. It does
not shake as you describe yours. Even when I first flew it
with the carbs significantly out of synch it was smooth. The
only shaking it does is on shutdown. Since you've
already synched the carbs it should run like a sewing
machine. Sorry I can't tell you anything more than your
engine is not running properly.I looked up the info I
got from the HKS group.
" Jim
Carruthers fabricated the exhaust system for my HKS when he
did the install on my Avid. We contacted HKS in Japan
about exhaust system requirements and received a reply back
from an HKS engineer. He said the headers need to merge at
500mm for proper scavenging and the length after the
merge was not critical though he noted that installations
with excessively long pipes after the merge had experienced
rough idling issues. As far as individual headers with no
merge, there was an HKS on a Skyraider at OshKosh years ago
that had independent headers going to super trapp mufflers.
They had a difficult time getting the engine to run well and
it was way off on power. Jim routed my exhaust tubes to
merge as close to 500mm as room would allow in the cowling
and my engine runs fantastic. Right after the merge he
rolled a simple muffler can with no baffles and its pretty
quiet."
Hope this
helps,Rick
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