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lrm(at)skyhawg.com
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 Posted: Thu Jun 21, 2007 5:41 am Post subject: Prop/Exhaust comments requested. |
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Setting the scenario.
I have a Harley 95B on my 701.
I am experiencing what I consider excessive vibration, so much so that I don't want to fly it.
I have tried three props, 3 blade warp drive, I had a blade that was tracking out by a 1/4". Warp Drive said it was within their acceptable tolerances. I disagreed, sold it on e-bay.
I tried an IVO 3 blade prop. It was a lot worse. Sent it back got a full refund. They said they would give me a full refund if there was a problem with the prop, so there must have been a problem.
I now have a two blade Culver wood prop. It tracks out by 1/8". It's 70X50. The vibration is still unacceptable.
I am thinking of ordering a short 4 blade prop. The best it ever got was with the warp drive 3 blade even with the tracking problem. My thinking is that a balanced shorter 4 blade prop should offer the best possible solution? Comments on the prop situation, please.
Here's my exhaust situation. On the Harley I am using individual pipes with no cross over and a supertrapp muffler on each with maximum backpressure. Even with out any prop I don't think the engine runs as smooth as it should. Remember this is a counter balanced engine. It is supposed to run real smooth. I haven't tried it yet with out the mufflers, because I don't want a loud engine. Next week I am going to pull them off and try it. Comments on the muffler situation too please?
I am also very aware of the large power pulses a Harley has and the inherent problems that pulses can cause, however I am not the first to put a Harley on an aircraft and Brett reports to me that the others don't have my problems.
I am going to be out of town for a few days, so I won't be able to comment until Sunday or Monday. But thanks for you help. I am at my end. If fact if this "one more time" doesn't work, someone is going to get a good deal.
Larry, www.SkyHawg.com, N1345L [quote][b]
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Gig Giacona
Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA
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| Posted: Thu Jun 21, 2007 5:58 am Post subject: Re: Prop/Exhaust comments requested. |
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My first thought if you have tried 3 very different props and still have the vibration then odds are the problem isn't in the propbut somewhere else in the system.
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W.R. "Gig" Giacona
601XL Under Construction
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JerryHey
Joined: 05 May 2007
Posts: 30
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| Posted: Thu Jun 21, 2007 6:08 am Post subject: Prop/Exhaust comments requested. |
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Larry, not a Harley, but single rotor mazda's are under development and have a similar situation with large power pulses. Here is a video showing what is happening to the prop in response to the pulses. Absolutely scary. It is much worse on a flexible prop like Warp Drive or Ivo. The problem seems to be worse at lower rpm. Jerryhttp://www.radrotary.com/WL_original_damper.wmv
On Jun 21, 2007, at 9:37 AM, LRM wrote:
| Quote: | Setting the scenario.
I have a Harley 95B on my 701.
I am experiencing what I consider excessive vibration, so much so that I don't want to fly it.
I have tried three props, 3 blade warp drive, I had a blade that was tracking out by a 1/4". Warp Drive said it was within their acceptable tolerances. I disagreed, sold it on e-bay.
I tried an IVO 3 blade prop. It was a lot worse. Sent it back got a full refund. They said they would give me a full refund if there was a problem with the prop, so there must have been a problem.
I now have a two blade Culver wood prop. It tracks out by 1/8". It's 70X50. The vibration is still unacceptable.
I am thinking of ordering a short 4 blade prop. The best it ever got was with the warp drive 3 blade even with the tracking problem. My thinking is that a balanced shorter 4 blade prop should offer the best possible solution? Comments on the prop situation, please.
Here's my exhaust situation. On the Harley I am using individual pipes with no cross over and a supertrapp muffler on each with maximum backpressure. Even with out any prop I don't think the engine runs as smooth as it should. Remember this is a counter balanced engine. It is supposed to run real smooth. I haven't tried it yet with out the mufflers, because I don't want a loud engine. Next week I am going to pull them off and try it. Comments on the muffler situation too please?
I am also very aware of the large power pulses a Harley has and the inherent problems that pulses can cause, however I am not the first to put a Harley on an aircraft and Brett reports to me that the others don't have my problems.
I am going to be out of town for a few days, so I won't be able to comment until Sunday or Monday. But thanks for you help. I am at my end. If fact if this "one more time" doesn't work, someone is going to get a good deal.
Larry, www.SkyHawg.com, N1345L |
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larry(at)macsmachine.com
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| Posted: Thu Jun 21, 2007 7:24 am Post subject: Prop/Exhaust comments requested. |
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Hi Larry,
No good answers here,,,
The prop issue is flexibility and weight.
If the prop flexes, it probably magnifies the vibration. Most props are
light, but I'd bet a metal prop would flex less and its weight might
dampen things a little.
The engine mount for a 701 radially, isn't a match for the longitudinal
mass of a Harley motorcycle frame. You going to feel that pulse more on
the 701,,,,,, but possibly for a shorter period of time.
On noise, the Harley should always be toned down with a good muffler,
preferably pointed rearward. They've got a lot of bad press without
mufflers and that "classic sound" has been overplayed in straight pipes.
If you fall out of the sky after irritating the lawn-bound griller's
with a noisy plane, will anybody down there search for you?
Larry McFarland 601HDS at www.macsmachine.com
do not archive
LRM wrote:
| Quote: | Setting the scenario.
I have a Harley 95B on my 701.
I am experiencing what I consider excessive vibration, so much so that
I don't want to fly it.
_/Comments on the prop situation, please./_
/_Comments on the muffler situation too please?_/
I am also very aware of the large power pulses a Harley has and the
inherent problems that pulses can cause,
I am going to be out of town for a few days, so I won't be able to
comment until Sunday or Monday. But thanks for you help. I am at my
end. If fact if this "one more time" doesn't work, someone is going
to get a good deal.
Larry, www.SkyHawg.com, N1345L
*==================================
*
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craig(at)craigandjean.com
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| Posted: Thu Jun 21, 2007 9:45 am Post subject: Prop/Exhaust comments requested. |
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Am I reading your post correctly? Did 2 out of 3 or 3 out of 3 props have
tracking issues? Is the flange or redrive the common factor? If you bolt a
straight edge to the prop flange how does the tracking look? This seems too
obvious so I assume you checked this - just wondering.
"someone is going to get a good deal"
Are you going to sell the whole plane or switch to another engine?
-- Craig
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Terry Phillips
Joined: 11 Jan 2006
Posts: 346
Location: Corvallis, MT
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| Posted: Thu Jun 21, 2007 10:17 am Post subject: Prop/Exhaust comments requested. |
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Larry
I appending a post by a LongEZE pilot that I read a few weeks ago on another list. He didn't have much of a problem to start with, but by doing a dynamic balancing, he was able to really smooth things out:
---------------------------------------------------------------------
Hello Group.
At the end of my yearly maintenance and condition inspection last
week I got my eze engine prop and crank dynamically balanced.
The results where much more then I had hoped for. The guy flew up to
Petaluma from Watson Vile, CA in a mustang II with his equipments and
tools to do this
at my hangar. Jeremy the guy who does this told me that he uses two
sensing pick ups one near the front of the engine and one near the
back of the engine.
He says he is one of the only ones in the country that uses two pick
ups. He set it all up with a photo sensor also that counts the
rotations of the prop for RPM data.
Once he was all ready I warmed up my engine and he had me run up to
2000 RPM and then 2100 RPM and hold it there for a few seconds until
he got his readings.
Then we stopped checked out the data and put one small bolt in one of
those holes that run all around the outside edge of the flywheel on
the 0320. I think they are every
60 degrees around the wheel. He told me the bad news was my
vibration was not too bad maybe in the 30% range of maximum allowable
so I might not realize much difference.
Next he had me run it up again then stop and check out the data.
This time the computer tells him how much weight and where to place
it. He moves the weight and changes size
with his gram scale to get the weight the instrument was calling
for. We did the test once more and we eliminated about two thirds of
the vibration from what I started out with. I could tell
it was running smoother. The amazing stuff happened next though. We
had lunch and he showed me a chart on a piece of paper that looks
like the little blips on a heart monitor or something like that.
He shows me one pulse and says thats your prop. Then he shows my a
big spike that happens three times for every revolution of the crank
shaft. He tells me we have to look at your engine and this is at
the prop end of your engine and we have to look for anything that may
be rotating three times per revolution. He has graph paper from the
sensor on the back and a graph paper for the one on the front too.
So we checked out and the engine after lunch and the only thing
there on the prop end to look at was the alternator.
We counted the times the pulley on the alternator turned as we
rotated the prop around exactly one time. Bingo. Three times. We
were pretty excited.
I had that belt off in a few seconds and spun the alternator pulley
around by hand and we could hear it grinding away. Wow it was like
the airplane doctor. Then he says I didn't like this other low
frequency blip
that is up on the other end of your engine. He says this looks like
a typical engine mount problem. So three of us checked out all four
engine mount rubbers and we clearly could see that the upper front one
had sagged enough to probably be going metal to metal occasionally.
So I went to the auto parts store and it took the guy a while but he
came out with a match for my alternator. Then a couple A&P's told me
when
a motor mount sags you can turn it around 180 degrees and it will
work for a while longer. I did that and it looks like the other
three mounts now. No sag at all.
So on my test flight I was amazed at how much smoother it feels in
the cockpit. Its a much much smoother now.
-----------------------------------------------------------------------
Jeremy is apparently, Jeremy MacDonald from Norcal Aero Services. I cannot speak from personal experience, but a dynamic analysis of your engine-propeller system might identify the problem. Good luck.
Terry
At 08:37 AM 6/21/2007 -0500, you wrote:
| Quote: | Setting the scenario.
I have a Harley 95B on my 701.
I am experiencing what I consider excessive vibration, so much so that I don't want to fly it.
I have tried three props, 3 blade warp drive, I had a blade that was tracking out by a 1/4". Warp Drive said it was within their acceptable tolerances. I disagreed, sold it on e-bay.
I tried an IVO 3 blade prop. It was a lot worse. Sent it back got a full refund. They said they would give me a full refund if there was a problem with the prop, so there must have been a problem.
I now have a two blade Culver wood prop. It tracks out by 1/8". It's 70X50. The vibration is still unacceptable.
I am thinking of ordering a short 4 blade prop. The best it ever got was with the warp drive 3 blade even with the tracking problem. My thinking is that a balanced shorter 4 blade prop should offer the best possible solution? Comments on the prop situation, please.
Here's my exhaust situation. On the Harley I am using individual pipes with no cross over and a supertrapp muffler on each with maximum backpressure. Even with out any prop I don't think the engine runs as smooth as it should. Remember this is a counter balanced engine. It is supposed to run real smooth. I haven't tried it yet with out the mufflers, because I don't want a loud engine. Next week I am going to pull them off and try it. Comments on the muffler situation too please?
I am also very aware of the large power pulses a Harley has and the inherent problems that pulses can cause, however I am not the first to put a Harley on an aircraft and Brett reports to me that the others don't have my problems.
I am going to be out of town for a few days, so I won't be able to comment until Sunday or Monday. But thanks for you help. I am at my end. If fact if this "one more time" doesn't work, someone is going to get a good deal.
Larry, www.SkyHawg.com, N1345L |
Terry Phillips
ttp44(at)rkymtn.net
[quote][b]
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_________________
Terry Phillips
Corvallis, MT
ttp44<at>rkymtn.net
Zenith 601XL/Jab 3300 slow build kit - Tail feathers done; working on the wings. |
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lrm(at)skyhawg.com
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| Posted: Thu Jun 21, 2007 6:09 pm Post subject: Prop/Exhaust comments requested. |
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If I can't solve this, some one is going to get a good deal on the engine
package. I also have a motorcycle guy real interested. But, this plane
will fly. Larry
---
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dave.thompson(at)verizon.
Guest
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| Posted: Fri Jun 22, 2007 5:24 pm Post subject: Prop/Exhaust comments requested. |
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I am by no means any kind of expert on this subject. However, when I read about the “Pulse vibration” I thought of the harmonic balancer that I added to my ’61 Corvair back in high school. ’65 and up had them, ’64 and below just had a pulley. There was a noticeable difference in the vibration after I add the harmonic balancer. I don’t know if there is an appropriate place to install one or if that would even help. I just wanted to pass along my thoughts.
Do not archive
Dave Thompson
Westminster, CA
[quote][b]
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