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The FireFly flies! (And it flies EXXCELLENT!)
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PostPosted: Wed Jul 19, 2017 4:43 am    Post subject: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

Hey Richard, congrats on getting the little bird flying! I liked the 1st flight takeoff video. George

Have a great day!

Quote:
On Jul 18, 2017, at 11:17 PM, Richard Pike <thegreybaron(at)charter.net> wrote:



Took it to the field of a friend, 3,000' grass strip (!) I flew it twice this morning, took off, climbed to 30', flew it down the runway and landed. Went back this evening to fly it some more, David & I both flew it for a total of 11 times, a bit over 2 hours. Burned 2.5 gallons of gas.
The 277 seems to be plenty of power, but IMO it vibrates a bit much. Maybe I am spoiled by 2 cylinder engines...
Performance is ideal for an ultralight, cruises at 54 mph at 4900 rpm, climbout at 45 indicated at 7-800 fpm. Should have gone ahead and put the requisite trim tab on the right aileron, and then it would have been trimmed right to start with. Will do that tomorrow.
Extremely pleased.
https://youtu.be/Rq8NCDpBg1A

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

Forgiving is tough. Being forgiven is wonderful.




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PostPosted: Wed Jul 19, 2017 5:09 am    Post subject: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

It seemed to get up in the air really quickly. Any wind? What was the finished weight?

Bill Sullivan
Windsor Locks, Ct.
--------------------------------------------
On Tue, 7/18/17, Richard Pike <thegreybaron(at)charter.net> wrote:

Subject: The FireFly flies! (And it flies EXXCELLENT!)
To: kolb-list(at)matronics.com
Date: Tuesday, July 18, 2017, 11:17 PM


Pike" <thegreybaron(at)charter.net>

Took it to the field of a friend,
3,000' grass strip (!) I flew it twice this morning, took
off, climbed to 30', flew it down the runway and landed.
Went back this evening to fly it some more, David & I
both flew it for a total of 11 times, a bit over 2 hours.
Burned 2.5 gallons of gas.
The 277 seems to be plenty of power,
but IMO it vibrates a bit much.

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


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John Hauck



Joined: 09 Jan 2006
Posts: 4627
Location: Titus, Alabama (hauck's holler)

PostPosted: Wed Jul 19, 2017 5:40 am    Post subject: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

Congratulations on the new Fire Fly.

Glad it performed well.



john h
mkIII
Titus, Alabama


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lcottrell



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PostPosted: Wed Jul 19, 2017 6:32 am    Post subject: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

How in the world did you find an operating 277? It seemed to do just fine with it. I am considering repainting my plane back to blue again. I'm having a hard time sneaking up on my neighbor next door.

Congratulations
Larry
On Tue, Jul 18, 2017 at 9:17 PM, Richard Pike <thegreybaron(at)charter.net (thegreybaron(at)charter.net)> wrote:
Quote:
--> Kolb-List message posted by: "Richard Pike" <thegreybaron(at)charter.net (thegreybaron(at)charter.net)>

Took it to the field of a friend, 3,000' grass strip (!) I flew it twice this morning, took off, climbed to 30', flew it down the runway and landed. Went back this evening to fly it some more, David & I both flew it for a total of 11 times, a bit over 2 hours. Burned 2.5 gallons of gas.
The 277 seems to be plenty of power, but IMO it vibrates a bit much. Maybe I am spoiled by 2 cylinder engines...
Performance is ideal for an ultralight, cruises at 54 mph at 4900 rpm, climbout at 45 indicated at 7-800 fpm. Should have gone ahead and put the requisite trim tab on the right aileron, and then it would have been trimmed right to start with. Will do that tomorrow.
Extremely pleased.
https://youtu.be/Rq8NCDpBg1A

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

Forgiving is tough. Being forgiven is wonderful.




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Richard Pike



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PostPosted: Wed Jul 19, 2017 9:48 am    Post subject: Re: The FireFly flies! (And it flies EXCELLENT!) Reply with quote

We are still struggling with the weight, our cheesy bathroom scales say it is ~260, it could be legal, but we don't know what it actually weighs. Even with these bogus scales it at least falls within the W&B envelope. Got an A&P friend with real scales, will get him to weigh it. Anyway, it is very close to legal U/L weight and we are not done fiddling with that part yet; we are determined that it is going to end up legal.
Flight yesterday was with no wind, it accelerates slower on the flat than the other Kolbs due to the small engine, but once it gets off, it climbs really good because of the light weight.
We found a local guy who had purchased a 277 and sent it to Lockwood and had it totally rebuilt, it has a 2.58:1 A box on it, 64" 2 blade Ivoprop. It runs really smooth at cruise power, but vibrates a lot at idle, don't yet know why.
Will be putting a trim tab on the right aileron this evening and hoping to fly it to it's permanent home. Nice little 28 mile cross country.


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Richard Pike
Kolb MKIII N420P (420ldPoops)
Kolb Firefly Part 103 legal (Redoing the Firefly windshield)
Kingsport, TN 3TN0

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PostPosted: Wed Jul 19, 2017 9:59 am    Post subject: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

Very nice. All I can suggest is to re-read Jack Hart's web site for dietary suggestions. Anybody hear from him lately?

Bil Sullivan
--------------------------------------------
On Wed, 7/19/17, Richard Pike <thegreybaron(at)charter.net> wrote:

Subject: Re: The FireFly flies! (And it flies EXXCELLENT!)
To: kolb-list(at)matronics.com
Date: Wednesday, July 19, 2017, 1:48 PM


Pike" <thegreybaron(at)charter.net>

We are still struggling with the
weight, our cheesy bathroom scales say it is ~260, it could
be legal, but we don't know what it actually weighs. Even
with these bogus scales it at least falls within the W&B
envelope.


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John Hauck



Joined: 09 Jan 2006
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PostPosted: Wed Jul 19, 2017 10:08 am    Post subject: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

Does it still have the same vibration problem at high idle? At what RPM
does it clean up?

Over the years I have seen most folks try to slow idle all models of the
Rotax, while the engine it trying to eat itself with adverse feedback and
gear box chatter.

If it was mine, I'd idle it fast enough to get out of the vibrations mode,
if that is possible, and still being able to comfortably control the
aircraft.

john h
mkIII
Titus, Alabama

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PostPosted: Wed Jul 19, 2017 10:47 am    Post subject: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

On Wed, 7/19/17, John Hauck <jhauck(at)elmore.rr.com> wrote:

"... while the engine it trying to eat itself with adverse feedback and gear box chatter.

If it was mine, I'd idle it fast enough to get out of the vibrations mode, ..."

Agree 100%. I have very little experience with 2 stroke engines, but I do know that harmonic vibrations and harsh load reversals are bad for any engine. There is little or no upside to operating any engine in an RPM range that creates bad vicrations. Any experienced pilot will tell you that an airplane will "talk to you" and tell you when it's happy or unhappy.


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Richard Pike



Joined: 09 Jan 2006
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Location: Blountville, Tennessee

PostPosted: Wed Jul 19, 2017 1:19 pm    Post subject: Re: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

It cleans up at around 3500. I am wondering if the power pulses of a single and the coupling design of the A & B gearboxes is not going to make for a happy relationship? Years ago I had a 277 on my Hummer with the Maxair belt drive and it was smooth as silk. Might have to look into trying to scrounge up an old belt redrive.

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Richard Pike
Kolb MKIII N420P (420ldPoops)
Kolb Firefly Part 103 legal (Redoing the Firefly windshield)
Kingsport, TN 3TN0

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Radegast



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PostPosted: Wed Jul 19, 2017 1:24 pm    Post subject: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

Check the MMOI (Mass Moment of Inertia) of your propeller.  Your propeller may be too heavy.

From: Richard Pike (thegreybaron(at)charter.net)
Sent: Wednesday, July 19, 2017 3:21 PM
To: kolb-list(at)matronics.com (kolb-list(at)matronics.com)
Subject: Re: The FireFly flies! (And it flies EXXCELLENT!)


--> Kolb-List message posted by: "Richard Pike" <thegreybaron(at)charter.net>

It cleans up at around 3500. I am wondering if the power pulses of a single and the coupling design of the A & B gearboxes is not going to make for a happy relationship? Years ago I had a 277 on my Hummer with the Maxair belt drive and it was smooth as silk. Might have to look into trying to scrounge up an old belt redrive.

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

Forgiving is tough. Being forgiven is wonderful.




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Richard Pike



Joined: 09 Jan 2006
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Location: Blountville, Tennessee

PostPosted: Wed Jul 19, 2017 6:06 pm    Post subject: Re: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

Prop weight is well within range for an A or B box, it is a new two blade 64" Ivo, so that is minimal, but something is screwy with whatever we are doing. We idled it up to 3,000 minimum and got rid of all the single cylinder/gearbox shake at idle, but then trying to land it was a pain - float and float some more. So idled it back down to 2,200 so you can slow down on approach and then throttle it right back up to 3,000 once you get down and settled. So you only have a few moments of excessive shake.

But that is not the problem; the problem is that even when it is running comparitively smoothly (at) 3,000 rpm or over, this thing simply vibrates way more than any airplane or U/L I have ever flown, something is not right.

The little engine runs fine, flew it a short 30 mile cross country this evening from the big grass strip where we did our test flights to the field where it will be living for the next few months, and the only rpm that doesn't vibrate excessively is right at 5,200, everything else you can feel the vibration all through the airframe.

Something Dave pointed out is that when we first got this airplane it had a 447 on it; after we put the airframe back together and ran it up, that engine vibrated excessively just like this one does. I am starting to wonder about our Lord mounts.

But right now we are open to all suggestions. Tomorrow I'll post some pictures of the engine/mounts, etc.


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Richard Pike
Kolb MKIII N420P (420ldPoops)
Kolb Firefly Part 103 legal (Redoing the Firefly windshield)
Kingsport, TN 3TN0

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PostPosted: Wed Jul 19, 2017 7:59 pm    Post subject: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

On 7/19/2017 9:06 PM, Richard Pike wrote:
Quote:


Prop weight is well within range for an A or B box, it is a new two blade 64" Ivo, so that is minimal, but something is screwy with whatever we are doing. We idled it up to 3,000 minimum and got rid of all the single cylinder/gearbox shake at idle, but then trying to land it was a pain - float and float some more. So idled it back down to 2,200 so you can slow down on approach and then throttle it right back up to 3,000 once you get down and settled. So you only have a few moments of excessive shake.

But that is not the problem; the problem is that even when it is running comparitively smoothly (at) 3,000 rpm or over, this thing simply vibrates way more than any airplane or U/L I have ever flown, something is not right.

The little engine runs fine, flew it a short 30 mile cross country this evening from the big grass strip where we did our test flights to the field where it will be living for the next few months, and the only rpm that doesn't vibrate excessively is right at 5,200, everything else you can feel the vibration all through the airframe.

Something Dave pointed out is that when we first got this airplane it had a 447 on it; after we put the airframe back together and ran it up, that engine vibrated excessively just like this one does. I am starting to wonder about our Lord mounts.

But right now we are open to all suggestions. Tomorrow I'll post some pictures of the engine/mounts, etc.

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

Richard,


I don't remember seeing many UL/light plane guys talk about prop
balance; particularly dynamic balance. But it might be worth a look,
especially if an EAA chapter nearby has a dynamic prop balancer for loan
or rent (ours does, here in central MS).

What you're describing could easily be caused by prop imbalance. It's
the nature of the beast that we notice lower frequency vibes, but are
not sensitive to higher frequencies. So your vibe may be there all
across the rpm spectrum, but you just can't feel it when the engine's
running at higher rpm.

There's also the issue of resonance. Your particular combination of
prop, gearbox, engine, airframe, mount cushions, etc may be near its
system resonance in the range they you're able to idle the engine
effectively. Any imbalance may be conspiring with a possible resonant
freq that's near your idle rpm to give you severe vibes in that range.

Without actual data it's just wild speculation, but something to consider.

Charlie

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wakataka



Joined: 11 Aug 2012
Posts: 43

PostPosted: Wed Jul 19, 2017 9:12 pm    Post subject: Re: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

Richard -

Congratulations on the successful first flight. I had about 100 hours on 277 engines before I went to Kawasaki, mainly to avoid vibration that was tearing up my airframe. The 277 is a really powerful and light weight little engine, but it does vibrate more than any 2 cylinder I've ever flown. I had one of those dynamic prop balancer thingies on mine and it helped just a bit. Not sure it was worth the extra weight, particularly if you are striving to make it legal.
One thing you might want to check the spring washers in the gearbox. If spring washers get weak there will be excessive 'give' in the knuckle joint. It can make the engine shake really bad at low RPM. If you're hearing a clacking noise associated with the vibration, suspect your spring washers. There was a service bulletin on the A gearbox. It originally had something like 9 spring washers and it was updated to 12. Same shaft, just more washers packed onto it to tighten up the knuckle joint. B boxes always had the larger number of spring washers. I'll try to attach the service bulletin and the gearbox repair instructions from the CPS catalog.

I was able to do the spring washer replacement in a big bench vise using a big socket in place of the special Rotax tool, which is no longer available. If you read the Rotax manuals, they say the spring washers should be replaced something like every 100 hours. Nobody I know does that, but if the spring washers do get weak, it will make your engine shake like crazy, be hard to start, and sometimes hard to get to come off idle.


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Richard Pike



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PostPosted: Thu Jul 20, 2017 5:09 am    Post subject: Re: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

Thanks for those instructions Wakataka, the engine and gearbox are a new rebuild from Lockwood, the engine is very easy to start - usually one pull, and it has no problems coming off idle. Nevertheless, we may still need to take the box apart to have a look and those instructions will be necessary.

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Richard Pike
Kolb MKIII N420P (420ldPoops)
Kolb Firefly Part 103 legal (Redoing the Firefly windshield)
Kingsport, TN 3TN0

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Richard Pike



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PostPosted: Thu Jul 20, 2017 10:36 am    Post subject: Re: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

I think we found the vibration problem; we think that dummy Pike designed the rubber muffler hangars incorrectly, allowing a harmonic resonance to set up between the engine and the muffler. Will fabricate new rubber hangars this afternoon to replace the ones that got destroyed in only 3.5 hours of flight, and run it up tomorrow so we can watch it close and see what is happening in that area.
Thanks for all the helpful suggestions.


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Richard Pike
Kolb MKIII N420P (420ldPoops)
Kolb Firefly Part 103 legal (Redoing the Firefly windshield)
Kingsport, TN 3TN0

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PostPosted: Thu Jul 20, 2017 7:16 pm    Post subject: Re: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

At least the Ultra Bug is in good company while we try and figure out how to make it's shakes go away:

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Richard Pike
Kolb MKIII N420P (420ldPoops)
Kolb Firefly Part 103 legal (Redoing the Firefly windshield)
Kingsport, TN 3TN0

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lcottrell



Joined: 29 May 2006
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Location: Jordan Valley, Or

PostPosted: Thu Jul 20, 2017 7:55 pm    Post subject: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

Must of had a sale on blue paint.  Smile

Larry
On Thu, Jul 20, 2017 at 9:16 PM, Richard Pike <thegreybaron(at)charter.net (thegreybaron(at)charter.net)> wrote:
Quote:
--> Kolb-List message posted by: "Richard Pike" <thegreybaron(at)charter.net (thegreybaron(at)charter.net)>

At least the Ultra Bug is in good company while we try and figure out how to make it's shakes go away:

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

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PostPosted: Fri Jul 21, 2017 5:34 pm    Post subject: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

Gentlemen:The propeller is by far the larges rotating mass and therefore the largest potential for vibration.  From your discussion I am confident your propeller is out of balance.  Swap in a known good propeller.  I expect your vibration will disappear. 
Jim
Mk3 Pilot
On Wed, Jul 19, 2017 at 9:02 PM, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:
Quote:
--> Kolb-List message posted by: Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)>

On 7/19/2017 9:06 PM, Richard Pike wrote:
Quote:
--> Kolb-List message posted by: "Richard Pike" <thegreybaron(at)charter.net (thegreybaron(at)charter.net)>

Prop weight is well within range for an A or B box, it is a new two blade 64" Ivo, so that is minimal, but something is screwy with whatever we are doing. We idled it up to 3,000 minimum and got rid of all the single cylinder/gearbox shake at idle, but then trying to land it was a pain - float and float some more. So idled it back down to 2,200 so you can slow down on approach and then throttle it right back up to 3,000 once you get down and settled. So you only have a few moments of excessive shake.

But that is not the problem; the problem is that even when it is running comparitively smoothly (at) 3,000 rpm or over, this thing simply vibrates way more than any airplane or U/L I have ever flown, something is not right.

The little engine runs fine, flew it a short 30 mile cross country this evening from the big grass strip where we did our test flights to the field where it will be living for the next few months, and the only rpm that doesn't vibrate excessively is right at 5,200, everything else you can feel the vibration all through the airframe.

Something Dave pointed out is that when we first got this airplane it had a 447 on it; after we put the airframe back together and ran it up, that engine vibrated excessively just like this one does. I am starting to wonder about our Lord mounts.

But right now we are open to all suggestions. Tomorrow I'll post some pictures of the engine/mounts, etc.

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

Richard,

I don't remember seeing many UL/light plane guys talk about prop balance; particularly dynamic balance. But it might be worth a look, especially if an EAA chapter nearby has a dynamic prop balancer for loan or rent (ours does, here in central MS).

What you're describing could easily be caused by prop imbalance. It's the nature of the beast that we notice lower frequency vibes, but are not sensitive to higher frequencies. So your vibe may be there all across the rpm spectrum, but you just can't feel it when the engine's running at higher rpm.

There's also the issue of resonance. Your particular combination of prop, gearbox, engine, airframe, mount cushions, etc may be near its system resonance in the range they you're able to idle the engine effectively. Any imbalance may be conspiring with a possible resonant freq that's near your idle rpm to give you severe vibes in that range.

Without actual data it's just wild speculation, but something to consider.

Charlie

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Richard Pike



Joined: 09 Jan 2006
Posts: 1527
Location: Blountville, Tennessee

PostPosted: Fri Jul 21, 2017 6:50 pm    Post subject: Re: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

Problem appears to be resolved. It was in how I had tied the muffler to the head braces via the rubber exhaust hangers. I had them too tight, and it set up a resonant interaction between the engine and the muffler. Consequently - during a 1 hour flight - it broke 3 out of the 4 muffler hangars. These are the exact same hangars I use on my MKIII, and typically they last several years, and then I replace them just as a precaution, not because they are damaged or worn.
Ran it a bunch with the new rubber hangars this morning, vibration was about 90% better, flew it a couple times while adjusting the aileron pushrods and resizing the right aileron trim tab, and I think we are about to get it whipped.

We would like to change the muffler configuration: if anybody has a Rotax straight exhaust expansion cone (A- "Straight" Exhaust in the attachment) and you want to sell it, let me know. Would also consider a "C" exhaust as in the jpeg.


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Richard Pike
Kolb MKIII N420P (420ldPoops)
Kolb Firefly Part 103 legal (Redoing the Firefly windshield)
Kingsport, TN 3TN0

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Richard Pike



Joined: 09 Jan 2006
Posts: 1527
Location: Blountville, Tennessee

PostPosted: Sat Nov 18, 2017 10:21 am    Post subject: Re: The FireFly flies! (And it flies EXXCELLENT!) Reply with quote

The vibration is now 99% GONE. Over 5,000 rpm it is as smooth as the 582 on the MKIII, between 5,000 and 4,600 you can feel it just a little.

The support bracket is welded to a base that is clamped securely to the the beefy end of the spar carrythrough. Rubber hangars are the usual ones from Advance Auto Parts. I got the tapered cone from Jegs hot rod supplies for $33. A lot cheaper than getting one from Rotax... The length for the cone came from an old LEAF catalog, used the muffler inlet diameter & exhaust ball socket outlet diameter to claculate the cone length & taper, must have got it right, it runs perfect and the EGT's are good.
This whole rig might actually be just as light or lighter than the original hang-it-off-the-head arrangement. Surprisingly it is not any noiser.


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Richard Pike
Kolb MKIII N420P (420ldPoops)
Kolb Firefly Part 103 legal (Redoing the Firefly windshield)
Kingsport, TN 3TN0

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