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My Firestar Project Update

 
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victorbravo(at)sbcglobal.
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PostPosted: Wed Dec 27, 2017 10:53 pm    Post subject: My Firestar Project Update Reply with quote

FINALLY figured out how to compress the photos from my camera down to a size that can go out on the Kolb Mail List !

Attached are three photos.

My new Super-STOL high AoA landing gear, steel legs taken from a damaged Kolb Slingshot, equipped with beautiful huge bushwheels thanks to the generosity of a well known Kolber.

My new stainless 2 into 1 exhaust system for the HKS engine, fabricated and partially tack-welded together.

A close-up of the upper part of the exhaust, where the pipes have to bend immediately inboard, in order to clear the trailing edge of the wing s when folded.

I just got the stainless screen material for my homebuilt "Swiss Muffler", rounded up the fiberglass cloth absorbent material "stuffing",a nd I'm waiting for the aluminum tube outer casing. The muffler will be 4 inches OD by 48 inches long. I hope to have the quietest ultralight/LSA style aircraft possible.

Bill Berle FS2 / HKS 700E, almost complete...almost...almost

--------------------------------------------
On Wed, 12/27/17, Larry Cottrell <lcottrell1020(at)gmail.com> wrote:

Subject: Re: Re: Baby has new shoes
To: "kolb-list(at)matronics.com" <kolb-list(at)matronics.com>
Date: Wednesday, December 27, 2017, 9:47 PM

Glad that you liked
it.Larry
On Wed, Dec 27, 2017
at 9:52 PM, Steeve77 <steevejackson73(at)gmail.com>
wrote:

"Steeve77" <steevejackson73(at)gmail.com>



This one is good.









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viewtopic.php?p=476827#476827













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Richard Pike



Joined: 09 Jan 2006
Posts: 1519
Location: Blountville, Tennessee

PostPosted: Thu Dec 28, 2017 8:10 am    Post subject: Re: My Firestar Project Update Reply with quote

Nice looking exhaust. Does it have a flex fitting in it anywhere?

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_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kolb Firefly Part 103 legal (Repairing the fiberglass nose bowl. Ugh.)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.
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PostPosted: Thu Dec 28, 2017 10:03 am    Post subject: My Firestar Project Update Reply with quote

First, before any of this was built, I consulted with a real live aircraft engineer who is an expert on material stress, metallurgy, etc. None of this was just me making assumptions or guesses. It is of course completely experimental, and may need mofidications, but the point is that there were a lot more brain cells on the job than mine Smile

Second, what is shown in the photo is the PARTIALLY completed exhaust, tack-welded together. There will be another "L shaped" pipe with a 90 degree bend added at the bottom, and that bend will go into a "Swiss Muffler" of the type described by Tony Bingelis in his Firewall Forward series of books. The Swiss Muffler has been proven to work extremely well and provide the least back-pressure/power loss.

So with that said, yes the exhaust will indeed have a flex fitting at the bottom betweem the part you see in the photo and the "L bend" section I mentioned.

The exhaust will be mounted solidly to the engine at the top, bolted to the exhaust flanges on the cylinders, AND welded lugs a few inches away that attach to bolts on the engine case. Having these two solid attach points near the top will prevent any twisting or flexing at the exhaust flange.

At the mid-point of the exhaust we will fabricate some sort of a "restraining collar" mounted to the airframe, that will prevent the two exhaust pipes from moving rearward toward the propeller. But this collar is not a "solid" mount at all, it will allow the exhaust pipes to expand, contract, and move slightly side to side. This side to side movement will be necessary because the engine will "rock" left and right (parallel to the roll axis of the aircraft).

At the bottom of what is shown in the photo, where the two pipes join, there will be a short section of pipe that turns rearward underneath the tailboom. That is where the flex pipe or ball/spring joint will be. At this location the exhaust pipe will end, and slip-fit into the front end of the muffler .

The muffler will be mounted to the tailboom with some sort of muffler hanger hardware and rubber blocks. Perhaps I can find some sutomotive hardware that will work. Perhaps I will have to fabricate some parts. But in general, I plan to use large diameter aircraft grade (rubber padding) Adel clamps around the tailboom tube, and similar Adel clamps around the muffler (4 inch diameter), and then some sort of flexible coupling between them. The intention is for the muffler to have significant range of movement, so the bottom of the exhaust can swing back and forth.

"Why the heck didn't he just use the OEM exhaust system that came with the HKS engine???"

Trust me, I started with that. But it simply would not fit on the Kolb airframe. The HKS exhaust would prevent the wings from being folded, there was solid interference between the HKS system and the Kolb aileron torque tubes. The only way it would fit is if I raised the engine up a few inches higher on spacers. From reading the Kolb list I learned that it is very well worthwhile to have the engine thrust line as low as possible. I believe that it will be worth the effort that this custom exhaust required, because I was able to mount the engine on 2 inch spacers instead of 4 or 5 inch spacers.

Anyway, sorry for the long message Smile

Bill Berle
www.ezflaphandle.com  - safety & performance upgrade for light aircraft
www.grantstar.net           - winning proposals for non-profit and for-profit entities

--------------------------------------------
On Thu, 12/28/17, Richard Pike <thegreybaron(at)charter.net> wrote:

Subject: Re: My Firestar Project Update
To: kolb-list(at)matronics.com
Date: Thursday, December 28, 2017, 8:10 AM


Pike" <thegreybaron(at)charter.net>

Nice looking exhaust. Does it have a
flex fitting in it anywhere?

--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is
wonderful, and Grace really is amazing.




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Richard Pike



Joined: 09 Jan 2006
Posts: 1519
Location: Blountville, Tennessee

PostPosted: Thu Dec 28, 2017 8:58 pm    Post subject: Re: My Firestar Project Update Reply with quote

I hate to sound critical because I always have to redo all my stuff 3 times before I can get it to work right, so that says a lot for my eyeball engineering... (Starting the redo on the gap seal for the forth time tomorrow) And meanwhile all your work in those pictures is way ahead of anything I can do in terms of quality control. So I feel like a shade tree mechanic telling a pro how to do his stuff.

But - just looking at your pictures, if it was me, I would have your two exhaust pipes come together right behind the rear main fuselage tube, because that is almost exactly aligned with the center of pivot of the engine on its motor mounts. Yours extend down way beyond that. If it were me, I would terminate them there with a Y into a ball joint.

By doing that, all the radial movement of the engine would sort of focus at that point. So if you had your ball joint there, with just one pipe going down to the rest of the exhaust assembly, now you have isolated the engine movement from the main mass of the exhaust system, and taken a lot of stress off the upper exhaust pipes. And possibly eliminated some vibration, because you have also removed some exhaust system mass from the engine and it's associated movements, and what movement there is, is now minimized by having it aligned with the center axis of the motor mounts, at which point you have a movable ball joint.

Worth what ya paid for it...


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_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kolb Firefly Part 103 legal (Repairing the fiberglass nose bowl. Ugh.)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.
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PostPosted: Fri Dec 29, 2017 12:06 am    Post subject: My Firestar Project Update Reply with quote

Richard thank you for your observation and compliments. My work is nowhere near the quality and finish of champion trophy airplane builders. 90% of what I am doing is not for "show quality", but simply to remove as many failure points and potential rubbing, chafing, scratching and abrasion between parts. I spent a lot of time putting pieces of split rubber tubing over the steel frame tubes where I want to attach something with a Ty-Rap (zip-tie), so nothing would start eating into the steel tubes. Hours were spent on this kind of stuff while I was building the fuel system. I used HDPE plastic tube everywhere I could run the lines fairly straight, and used the blue urethane tube only where it needed to make bends or flex a little. Lots of "EAA homebuilder standoff" assemblies in the engine area. These are short lengths of tube with a zip-tie through the tube and around something on either end,which basically prevents lines, wires, tubes, etc. from "whipping" and waearing out prematurely. No rocket science whatsoever, but it makes everything last longer.

The direct answer to your suggestion about joining the exhaust pipes behind the main keel tube is that the HKS engine importer told me that the length of the tubes should be 22-24 inches before they join together. That distance, while not "critical" by any means, gives you the best "tuning" of the exhaust pulses helping pull the exhaust gas out of the cylinders. I used this as a starting point, knowing full well that to get the last percentage pof power form the engineyou'd have to do a bunhc of testing and dyno work like race engine builders do. I have no need for that, but I figured if the engine mfg. can give me a basic deimension then I can at least roll the dice on that.

BTW today I finished most of the fuel system. I madeup webbing strap and buckle assemblies to tie the fuel jugs down to the fuselage tube. I had glued a rubber strip on the top of the fuselage tube in the fuel tank bay, so the furl jug and aluminum tube would not start working on each other due to normal vibrations. Then, after scratching my head for a while and thinking about what could possibly wear, chafe, rub, or grind... I realized that the nylon webbin strap was directly rubbing on the bottom of the fuselage tube, and eventually might wear through something. So I took it apart and ran the webbing through two short pieces of foam rubber tubing, and reinstalled everything with the foam rubber tubing on the bottom, putting a layer of foam between the webbing and the bottom of the fuselage tube. So now the webbing can't rub through the paing on the fuselage tube, and the fuselage tube can't wear away any of the nylon webbing.

THEN, after more insane asylum paranoia, I realized that the plastic buckles that I put on the webbing wereplenty strong enough for any negative G loads on the fuel jugs... but the buckles were too easy to un-lock if someone brushed against them at the wrong angle. So after more head scratching, I figured out a way to use small zip ties as locking devices, preventing anyone from accidentally (or intentionally) squeezing the buckles to un-lock the fuel tank retaining straps.

I know that this is paranoid "certified airplane overkill" thinking, but I come from the certified airplane world as much as I come from the experimental world. So I take a LOT longer to be convinced somehting is safe.

Bill Berle
www.ezflaphandle.com  - safety & performance upgrade for light aircraft
www.grantstar.net           - winning proposals for non-profit and for-profit entities

--------------------------------------------
On Thu, 12/28/17, Richard Pike <thegreybaron(at)charter.net> wrote:

Subject: Re: My Firestar Project Update
To: kolb-list(at)matronics.com
Date: Thursday, December 28, 2017, 8:58 PM


Pike" <thegreybaron(at)charter.net>

I hate to sound critical because I
always have to redo all my stuff 3 times before I can get it
to work right, so that says a lot for my eyeball
engineering... (Starting the redo on the gap seal for the
forth time tomorrow) And meanwhile all your work in those
pictures is way ahead of anything I can do in terms of
quality control. So I feel like a shade tree mechanic
telling a pro how to do his stuff.

But - just looking at your pictures, if
it was me, I would have your two exhaust pipes come together
right behind the rear main fuselage tube, because that is
almost exactly aligned with the center of pivot of the
engine on its motor mounts. Yours extend down way beyond
that. If it were me, I would terminate them there with a Y
into a ball joint.

By doing that, all the radial movement
of the engine would sort of focus at that point. So if you
had your ball joint there, with just one pipe going down to
the rest of the exhaust assembly, now you have isolated the
engine movement from the main mass of the exhaust system,
and taken a lot of stress off the upper exhaust pipes. And
possibly eliminated some vibration, because you have also
removed some exhaust system mass from the engine and it's
associated movements, and what movement there is, is now
minimized by having it aligned with the center axis of the
motor mounts, at which point you have a movable ball joint.


Worth what ya paid for it...

--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is
wonderful, and Grace really is amazing.




Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=476847#476847






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    - MATRONICS WEB FORUMS -
via the Web Forums!
    - NEW MATRONICS LIST WIKI -
Email List Wiki!
  - List Contribution Web Site -
support!
               
    -Matt Dralle, List Admin.


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baberdk



Joined: 23 Jan 2014
Posts: 50
Location: East Moline, Il

PostPosted: Fri Dec 29, 2017 9:14 am    Post subject: My Firestar Project Update Reply with quote

 Two-cycle engines have their exhaust "tuned" to have a low-pressure wave at the exhaust port when the piston moves below the port. This helps pull fuel-air mixture into the cylinder while pulling the burnt gases out. I think it is determined by the length and size of the exhaust pipe so be careful you don't lose a lot of horsepower.

Respectfully,
Dennis Baber
Cape Coral, Fl
baberdk(at)gmail.com (baberdk(at)gmail.com)
Stay Curious


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PostPosted: Fri Dec 29, 2017 9:41 am    Post subject: My Firestar Project Update Reply with quote

The HKS is a four stroke, but I am using this same tuning principle anyway, based on the recommendations of the engine manufacturer.

Bill Berle
www.ezflaphandle.com  - safety & performance upgrade for light aircraft
www.grantstar.net           - winning proposals for non-profit and for-profit entities

--------------------------------------------
On Fri, 12/29/17, Denny Baber <baberdk(at)gmail.com> wrote:

Subject: Re: My Firestar Project Update
To: kolb-list(at)matronics.com
Date: Friday, December 29, 2017, 9:14 AM

 Two-cycle engines
have their exhaust "tuned" to have a low-pressure
wave at the exhaust port when the piston moves below the
port. This helps pull fuel-air mixture into the cylinder
while pulling the burnt gases out. I think it is determined
by the length and size of the exhaust pipe so be careful you
don't lose a lot of horsepower.


Respectfully,
Dennis BaberCape Coral,
Flbaberdk(at)gmail.com
Stay Curious


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