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Discouraging issues, looking for input

Yes. I think what happens is the airflow over the wing hits leading edge of the aileron causing a burble on top of the aileron. This is a low pressure event and sucks the aileron up. Mine at low speed wasn't to bad, but as speed increased the roll got worse.

YMMV, I could be completely off base, but dropping the outboard hinge of my left aileron ~1/16" took all the roll out.

I still had to deal with an unstable roll oscillation. I pinched BOTH ailerons to reshape the trailing edge a bit. All is well.
 
Yes. I think what happens is the airflow over the wing hits leading edge of the aileron causing a burble on top of the aileron. This is a low pressure event and sucks the aileron up. Mine at low speed wasn't to bad, but as speed increased the roll got worse.

YMMV, I could be completely off base, but dropping the outboard hinge of my left aileron ~1/16" took all the roll out.

I still had to deal with an unstable roll oscillation. I pinched BOTH ailerons to reshape the trailing edge a bit. All is well.

Just so I am sure, from your post 17 your left wing was heavy, and your left aileron was above the skin at the outboard hinge. You lowered the hinge and that corrected the roll issue. Correct?

If the aileron was lower than the wing skin, would that cause any issues?

Thanks again for the pic and info.
 
Just so I am sure, from your post 17 your left wing was heavy, and your left aileron was above the skin at the outboard hinge. You lowered the hinge and that corrected the roll issue. Correct?

If the aileron was lower than the wing skin, would that cause any issues?

Thanks again for the pic and info.

I just checked my ailerons. They aren't higher than the wing skin. I was hoping that was my answer but now I'm back where I started. Rigging is good, incidence, ball centered, tails straight, had leg fairings on and off, I just have no idea what it could be
 
Vibration

Ive had to rotate my exhause tips outward, this reduces my vibration.
My pipes were straight but talking to Vetterman allowed my realize the pulses
Were the cause.
 
Forgive me if you've done this, but have you pulled the plane out in the open, walked well out in front of it and just taken a good look at it? Look carefully for symmetry of wing tips, h-stab, gear, canopy, cowl, etc.
 
Forgive me if you've done this, but have you pulled the plane out in the open, walked well out in front of it and just taken a good look at it? Look carefully for symmetry of wing tips, h-stab, gear, canopy, cowl, etc.

I feel like ive done this 100 times. Thanks for the suggestion though.
 
Forgive me if you've done this, but have you pulled the plane out in the open, walked well out in front of it and just taken a good look at it? Look carefully for symmetry of wing tips, h-stab, gear, canopy, cowl, etc.

Actually one thing does come to mind, tip symmetry. I know the right hand wing tip fiberglass does droop slightly on the trailing edge, like it could be split and pulled upward. Not sure what a slight droop would do.
 
It's all about the ailerons...

It's all about the ailerons... the aileron flies the wing... what flies the aileron... very small changes to the aileron trailing edge result in large impacts to wing heaviness and control feel. Look closely at the cross sectional shape of the trailing edge bend and the radius of each aileron and compare the two. In general, a larger more bulbous radius is lighter in control feel but can become too light and unstable if too big... a tight radius, or joined trailing edge, is firmer in control and less responsive (7 vs 9). After checking rigging and looking closely at the differences in your ailerons tighten up the radius (squeeze) on the light side or ballon out the radius on the heavy side, bash it with a wood block and a heavy hammer... with caution ;)

Small change then test fly...
During testing DISCONNECT the spring aileron trim.
Remember that the pilot makes the left side heavy without a passenger in a side by side... you have to decide how you want to balance the plane... Solo with the extra weight on the left, or with a passenger...

I bent my trailing edge radius for stick feel and adjusted balance for neutral with a solo pilot... With a passenger I am a bit right wing heavy (probably about 6-8 gallons equivelant)
 
Well after a week of working on my plane to alleviate some issues, I have some updates.

Found two places inside the cowling where the metal baffle was touching the fiberglass. Aleviated the condition..
... plane still vibrates.

Made some adjustments to rigging..
... wing still heavy.

Lowered tire pressures per Joe Blank..
... plane still shimmys landing and takeoff.

I also cut down the air dams on the baffles because my front two CHTs are high, still high. Feel like I did a bunch of work for nothing. Even more discouraged.
 
Well after a week of working on my plane to alleviate some issues, I have some updates.

Found two places inside the cowling where the metal baffle was touching the fiberglass. Aleviated the condition..
... plane still vibrates.

Made some adjustments to rigging..
... wing still heavy.

Lowered tire pressures per Joe Blank..
... plane still shimmys landing and takeoff.

I also cut down the air dams on the baffles because my front two CHTs are high, still high. Feel like I did a bunch of work for nothing. Even more discouraged.


No...you didn't do a bunch of work for nothing, you eliminated some possible reasons for your squawks.....that is progress. We all go through this process of smoothing out the wrinkles in our homemade aircraft, some of us take years..... ;)

Keep working with it, every thing you try makes you more familiar with your plane and will better equip you to handle the additional squawks that will occur as you accumulate hours. At 30 hours you are just getting started... :)
 
ExperiMENTAL aircraft are about education. Heck, all aircraft are about education. Just take one thing a small bite at a time. You are making progress.
 
Heavy wing

Fix the heavy wing by adjusting the flap down on the heavy wing. Not aileron. This is standard fix on other production airplanes also. It will relieve your stick pressure and allow for hands off flight. Hopefully you wont have to adjust to far. Something or many things are causing it. Lowering the flap slightly creates lift on the heavy wing.
 
Wing heavy

I had the same wing heavy problem on my RV8. I did all the usual squeezing and bumping out of trailing edges getting some improvement. I then looked at the wing tips. Vans wingtips sometimes leave something to be desired as far as finish and shape go. One of my wing tips was fat at the trailing edge on the under side, so I sanded it down to get a flatter trailing edge, like squeezing the aileron edge. This was on the light wing side.
Guess what, the plane trims just right and doesn't get heavier at high speeds. Once that was done, I was able to tweak the aileron and flap trailing edges and had to actually undo some of what i had done.
In my experience, you sometimes have to really investigate the issue to determine what is really happening. Rerigging the flaps and/or ailerons should be the last thing to try. If the trailing edges all line up, they are probably just fine.
Hope this helps. Good luck.
 
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I had the same wing heavy problem on my RV8. I did all the usual squeezing and bumping out of trailing edges getting some improvement. I then looked at the wing tips. Vans wingtips sometimes leave something to be desired as far as finish and shape go. One of my wing tips was fat at the trailing edge on the under side, so I sanded it down to get a flatter trailing edge, like squeezing the aileron edge. This was on the light wing side.
Guess what, the plane trims just right and doesn't get heavier at high speeds. Once that was done, I was able to tweak the aileron and flap trailing edges and had to actually undo some of what i had done.
In my experience, you sometimes have to really investigate the issue to determine what is really happening. Rerigging the flaps and/or ailerons should be the last thing to try. If the trailing edges all line up, they are probably just fine.
Hope this helps. Good luck.


Thanks for the encouragement everyone.

And this is a great idea, I haven't looked at this yet. This will be my next step
 
Made some adjustments to rigging..... wing still heavy.

Is it as heavy as it was? Are you filling the tanks, flying high and burning the fuel in the heavy tank until it no longer is heavy and calculating how heavy it is? You need a benchmark to determine the progress you're making.

Lowered tire pressures per Joe Blank..
... plane still shimmys landing and takeoff.

I can't recall if you're a tailwheel or tri-gear. If the latter, have you doublechecked the break-out force on the nosewheel?

I also cut down the air dams on the baffles because my front two CHTs are high, still high. Feel like I did a bunch of work for nothing. Even more discouraged.

As high? Or less high? Cut some more. And check again. The only way to solve these are exactly the way you're approaching this: a little at a time.
 
Is it as heavy as it was? Are you filling the tanks, flying high and burning the fuel in the heavy tank until it no longer is heavy and calculating how heavy it is? You need a benchmark to determine the progress you're making.



I can't recall if you're a tailwheel or tri-gear. If the latter, have you doublechecked the break-out force on the nosewheel?



As high? Or less high? Cut some more. And check again. The only way to solve these are exactly the way you're approaching this: a little at a time.

I have not done a tank test to determine the amount of force because at this point im not sure what I would even do with that information. The heavy wing is significantly reduced. It can be drimmed out with partial aileron trim.

Its a tail wheel.

They may be just slightly less. Cylinder 1 is my highest, leaned out at 75% power it sits at just about 401 degrees in cruise. I either have to pull the power back to 65% or enrich the mixture
 
I have not done a tank test to determine the amount of force because at this point im not sure what I would even do with that information. The heavy wing is significantly reduced. It can be drimmed out with partial aileron trim.

Its a tail wheel.

They may be just slightly less. Cylinder 1 is my highest, leaned out at 75% power it sits at just about 401 degrees in cruise. I either have to pull the power back to 65% or enrich the mixture

Do what Van's advises on matters of heavy wing. Fill it up, take it up to 5,000 feet, flying on the heavy wing-side tank until it's not rolling (actually, you want it to roll a little.

Land.

Fill up that tank. Multiply number of gallons x 6. If it's less than 18, it's minor condition. But more than that, and you at least have a baseline for how severe your problem is AND you can easily see how your actions in solving the problem are affecting the problem.

I'm sure you've read this by now, but if not, here.

I think what I would recommend -- and I'm not expert -- is tackling one problem at a time. Sure, MAYBE they're all related, but maybe not. So pick one and let's get that solved and maybe some of the other problems will disappear with it.

The document on the heavy wing seems like a great place to start.
 
I had the same wing heavy problem on my RV8. I did all the usual squeezing and bumping out of trailing edges getting some improvement. I then looked at the wing tips. Vans wingtips sometimes leave something to be desired as far as finish and shape go. One of my wing tips was fat at the trailing edge on the under side, so I sanded it down to get a flatter trailing edge, like squeezing the aileron edge. This was on the light wing side.
Guess what, the plane trims just right and doesn't get heavier at high speeds. Once that was done, I was able to tweak the aileron and flap trailing edges and had to actually undo some of what i had done.
In my experience, you sometimes have to really investigate the issue to determine what is really happening. Rerigging the flaps and/or ailerons should be the last thing to try. If the trailing edges all line up, they are probably just fine.
Hope this helps. Good luck.

Ok I have an update based on some obvervations and changes I made yesterday and I wanted to see what you guys make of it.

I adjusted the flap on my heavy wing down one turn and I loosened the screws on the wing tip and tried to lower it slightly. When I took off it felt as if my right wing was slightly heavy, but when I sped up I still had the left heavy wing. From neutral trim it took about half of the available right trim to correct it. BUT straight and level flight had the left aileron high and the right aileron low (but my left wing is heavy). Not positive what this means but it kind of tells me that the ailerons were fighting against the lowered flap. The fact that before I made this change I had a left heavy wing but flaps and ailerons were in line during level flight and the ball is centered tells me I definitely have some sort of problem with the airflow around the ailerons. The second thing that happened is when I got down to landing speeds and lowered the flaps, not only did I have to trim back to the left as usual, but I had to trim PAST neutral and use left trim to stay level. I will be putting the flap back to where it was, but I am back to where I started. I want to see what you guys make of it, but I am kind of leaning toward an aileron symmetry problem. I feel like if it was a problem with something fixed (flap rigging, incidence, etc) I wouldn't be seeing everything in trail during level flight with a centered ball and having the trim springs keeping the ailerons from deflecting.

Now question about my vibration. Alleviating the baffle interference has reduced it but its still there. Now one thing I observed yesterday is during my mag check, I had a 100 rpm drop on the right mag, and a 50 rpm drop on the left. Could I have one bad plug causing the vibration? When installing the plugs I MAY have dropped one of them onto my shoe which MAY have then bounced onto the floor. Just putting that out there.
 
Matt, try conducting your mag check in flight at altitude. I assume you have an engine monitor, so watch your individual cylinder EGTs when you do this and see if it shows a cylinder dropping off line. If you did drop that plug, you may have a cracked insulator which is showing as ok on the ground, but failing in flight. Alternatively, if you know which cylinder has the questionable plug, put a known good replacement in and go fly. I've been told unequivocally to throw away plugs that have been dropped, period.
 
Matt, try conducting your mag check in flight at altitude. I assume you have an engine monitor, so watch your individual cylinder EGTs when you do this and see if it shows a cylinder dropping off line. If you did drop that plug, you may have a cracked insulator which is showing as ok on the ground, but failing in flight. Alternatively, if you know which cylinder has the questionable plug, put a known good replacement in and go fly. I've been told unequivocally to throw away plugs that have been dropped, period.

I've heard the same, so I'm looking for a significant drop in EGT?
 
Have you looked closely at wheel alignment? I realize it's unlikely, but I'll bet a grossly misaligned wheel could cause a plane to roll/yaw.
 
I've heard the same, so I'm looking for a significant drop in EGT?

Yes, if one of your two spark plugs is bad, when you do the inflight mag check, EGT will drop off to zero when you check the mag connected to the bad plug, because that spark plug will not be firing at all and therefore the mixture will not be burning. When you do a mag check, whether on the ground or in flight, and all plugs are firing, you should see EGTs go UP, because the mixture isn't burning as quickly (because only one plug is firing) and therefore the exhaust gas is hotter when it leaves the cylinder.
 
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Rigging per plans

Did you rig per plans as the beginning step?

This seems to be a critical starting point. There is a jig in the kit that locks the aileron bellcrank in centered position. At that point a string or straight edge is to be pulled across the tooling holes on the outboard wing rib and the aileron is adjusted to be centered on this line. Then the flap is adjusted to be in a straight line with the locked aileron and finally the wingtip is added in a straight line with the aileron. Repeat for the other side. When done and the stick is centered, elevator clamped straight, should be able to have wingtip, aileron and flap all in a straight line on both sides. Anything done by lowering flaps or adjusting ailerons from this point to correct anything is just drag. Should be able to fix any slight heaviness from there with the squeezing light wing aileron trailing edge adjustment. It should work out balanced or with very little heavy left wing for a side by side with only the pilot aboard, balanced with pilot and passenger.

This may be rehashing what you have already done, but just wanted to put it out there. I've seen some guys just try to make everything straight without using jig/string as outlined in the plans and have bad results.

Good luck!
 
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Be sure to check alignment of wheel fairings and pants. Especially on nosegear aircraft. If misaligned, they can play havoc on flight characteristics. I used a laser square and the string method as outlined in the plans.
 
Be sure to check alignment of wheel fairings and pants. Especially on nosegear aircraft. If misaligned, they can play havoc on flight characteristics. I used a laser square and the string method as outlined in the plans.

Wing heaviness doesn't change whether all fairings are on or off. Thanks for the suggestion though.
 
I did an in flight mag check yesterday, it appears all of my plugs are fine. My EGTs actually went up when I ran off one mag at cruise?

Anyway, I was having another thought. My mag check at runup shows a difference of 50 to 60 between the Right and Left. Could my vibration possibly be mag timing? This could also be the cause of my high CHTs. What do you guys think?
 
I think what I would recommend -- and I'm not expert -- is tackling one problem at a time. Sure, MAYBE they're all related, but maybe not. So pick one and let's get that solved and maybe some of the other problems will disappear with it.


First of all, I'm really sorry to hear about your issues, and I'm definitely not an RV expert, in fact I'm just ordering my RV-8A. I really hope my first flights aren't discouraging. It sounds like you're really frustrated (who wouldn't be) so I thought I'd offer a bit of advice. I think the quoted advice is something to really concentrate on. I'm a professional race car driver, and a lot of it really comes down to being a test engineer. Thankfully I have a background in astrophysics, so I am generally able to understand what's going on and communicate with engineers and mechanics and sort out most issues. At least you didn't go out and crash someone's brand new design on the first lap of the first time it was ever driven... yeah, btdt. But, we still had to put it back together, and then start back at every problem and solve them until it was not only drivable, but fast.

Anyway, I think you have three really great suggestions that you might want to concentrate on before letting this frustrate you to no end.

The first being to prioritize what problems you want to solve and concentrate on one at a time. I can't tell you how many people I've seen that are unhappy with the handling of a car and make 4 different large suspension setting changes and decide to bump up horsepower to make up for handling problems. They end up ready to sell or burn to the ground a car that could be fixed in one day of testing by a crew that were methodical. To me it sounds like the heavy wing would be top priority, then the vibration, then the shimmy.

The second suggestion you've been given that sounds really good is to have an EAA tech counselor come out and really get someone else's opinion on it which goes hand in hand with the third... maybe it's worth getting those 10 hours on the plane, even with a vibration and heavy wing, and having an experienced RV-8 pilot come in and at least give you feedback on how bad/normal/freaky/whatever the problems you're describing feel to them. Plus it never hurts having more eyes on the problem.

Anyway, like I said I'm no RV expert, but it just seemed like you had a lot of posts where you'd done a lot of work and were back at square one. So I wanted to give you a bit of encouragement. Like someone else said, you definitely haven't been doing work for no reason, but maybe it's time to bring in some help before you get really frustrated. Just focus on tackling one problem and only making ONE change/adjustment at a time and I bet it'll resolve itself faster than you think.

Good luck!
 
I did an in flight mag check yesterday, it appears all of my plugs are fine. My EGTs actually went up when I ran off one mag at cruise?

Anyway, I was having another thought. My mag check at runup shows a difference of 50 to 60 between the Right and Left. Could my vibration possibly be mag timing? This could also be the cause of my high CHTs. What do you guys think?

Yes, that's correct, your EGTs should go up when you do a mag check, because the fuel mixture is burning slower and when the exhaust valve opens, some of the mixture may still be burning resulting in the EGT probe seeing a higher temp. When both sparkplugs are firing, the mixture burns faster and by the time the exhaust valve opens, it's all burned by that time and the EGT probe sees a cooler temp.

In re: your RPM difference at run up, you are supposed to have a difference in RPM between the mags. I don't think your vibration problem is a result of your engine...I don't know what engine/prop combo you have but odds are that it's not that.

As some have recommended, I would ask a local RV veteran to go up with you and see what he thinks. I might also call Vans
 
Yes, that's correct, your EGTs should go up when you do a mag check, because the fuel mixture is burning slower and when the exhaust valve opens, some of the mixture may still be burning resulting in the EGT probe seeing a higher temp. When both sparkplugs are firing, the mixture burns faster and by the time the exhaust valve opens, it's all burned by that time and the EGT probe sees a cooler temp.

In re: your RPM difference at run up, you are supposed to have a difference in RPM between the mags. I don't think your vibration problem is a result of your engine...I don't know what engine/prop combo you have but odds are that it's not that.

As some have recommended, I would ask a local RV veteran to go up with you and see what he thinks. I might also call Vans

Vans' guess is that the vibration is something with the engine/prop. My mag timing turned out to be off a little, 25/27 which is within spec apparently but i adjusted it to be equal. Mags drops are now the same at runup (~90 rpm drop left and right). Didnt change vibs in flight.

I put a new set of tires on the plane, Desser Monster Retreads (awesome tires by the way), and the shimmy problem is gone. So at least I can say I've solved one.

Thanks for all the advice, this is what I am going to do. One at a time. Im moving on to the wing heavy only until I find a solution. Will report my results.
 
Phase one rules

I'm no expert on the phase one rules, but it seems to me if you need more brain power sitting in the right seat, I don't think the FAA would have a a problem with it. I certainly wouldn't hurt to ask. Being prepared with a specific goal for the flight and your right seater being qualified to help meet that goal should be all that's required. Putting these issues behind you is part of phase ones purpose. Waiting until you fly it off to get someone in there to help out doesn't make sense to me.
 
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I'm no expert on the phase one rules, but it seems to me if you need more brain power sitting in the right seat, I don't think the FAA would have a a problem with it. I certainly wouldn't hurt to ask. Being prepared with a specific goal for the flight and your right seater being qualified to help meet that goal should be all that's required. Putting these issues behind you is part of phase ones purpose. Waiting until you fly it off to get someone in there to help out doesn't make sense to me.

Sorry Andrew, but as much as that might make sense, especially in the latter stages of Phase 1, it certainly doesn't meet the letter of the (current) law according to many FAA interpretations. Of course, someone will immediately come along and tell us that their FSDO is OK with it...but that doesn't change the way that FAA HQ has interpretted it.

Of course, it only matters if you get ramp checked or otherwise stopped - the FAA rules are broken by lots of pilots every single day.
 
I'm no expert on the phase one rules, but it seems to me if you need more brain power sitting in the right seat, I don't think the FAA would have a a problem with it. I certainly wouldn't hurt to ask. Being prepared with a specific goal for the flight and your right seater being qualified to help meet that goal should be all that's required. Putting these issues behind you is part of phase ones purpose. Waiting until you fly it off to get someone in there to help out doesn't make sense to me.

The FAA will definitely have a problem with this. There is no gray area in the rules as written.
 
I'm no expert on the phase one rules, but it seems to me if you need more brain power sitting in the right seat, I don't think the FAA would have a a problem with it. I certainly wouldn't hurt to ask. Being prepared with a specific goal for the flight and your right seater being qualified to help meet that goal should be all that's required. Putting these issues behind you is part of phase ones purpose. Waiting until you fly it off to get someone in there to help out doesn't make sense to me.

If you have an RV expert or someone experienced that's going to help you later, can't they just fly part of Phase I now? Kind of like having someone do the first flight. Solo, of course.
 
If you have an RV expert or someone experienced that's going to help you later, can't they just fly part of Phase I now? Kind of like having someone do the first flight. Solo, of course.

This is exactly the way to go. Have a test pilot take her up and run her through the paces and report back with a list of squawks.

I'm actually kind of surprised that nobody on VAF who lives near you -- and surely there surely are some -- have popped in here to offer to stop by.
 
I've have lost track of the detail of this thread - but, have you checked the prop tracking?

Dan
 
After reading this thread I was flying today and noticed a really heavy left wing. Started getting paranoid about aileron hinges, etc. Then I realized i had15 in the left tank, 5 in the right, and all 250lb of me was on the left, too. Just a reminder to remember the easy stuff, don't get stressed out, and have fun.
 
Vibrations...

Next time you fly, try yawing the plane back and forth with the rudder and check to see if the vibrations change significantly in tone or strength as you yaw the plane from left to right past the "center". If it does, then that's a tell-tale sign of the back of the canopy skirt vibrating against the turtledeck of the rear fuselage as I'd mentioned earlier in this thread.
 
Well I have some updates.

I may have said this already, but changing the tires cured the shimmy on takeoff and landing 100%. Check that one off.

Narrowed the wing heavy down to aileron symmetry completely. With everything in trail, it flies straight and level with everything still in trail. But when y ou let go of the stick the ailerons deflect a little and it rolls. I took a 2x4 and a mallet per Van's and lightly tapped the trailing edge of the heavy wings aileron. So now it has an opposite heavy wing! At least now I can fine tune and solve the problem.

My biggest problem (I think) is still not solved. Vibration. Dynamic Prop balance didnt fix it. Its not the skirt or the fairings. Exhaust isnt hitting the airframe, baffles arent hitting the cowl (anymore). It seems to be RPM related. I just have no idea.
 
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Any more updates?

Is it REALLY RPM related.. or is it SPEED related?

I'm confused that you had it dynamically balanced,... yet you have vibration,... seems to me it would have indicated and issue if you had that done. (vibration not able to be corrected). Does it shake "on the ramp" or only while flying?

So,... is it something else,...a.) wing/fuse -seal/gasket loose? (been known to scare the bejimminies out of folks, when it wiggles out and starts shaking) b.) seal between cowl and inlet ramps not "fair and smooth",.. and shaking with air across it c.) wing walk non-skid pad coming loose and shaking air/wing d.) your other tires were out of round,... how does the tail wheel look,.. any abuse to it causing out of round? (as you found out, .. out of round tires shake) e.) all the access panels on tight? sure? f.) what about the bottom of the cowling... any chance the FAB is rubbing or hitting at some point.... they are known to have some fit-up and tweaking required depending on engine, carb/TB, and cowling arrangement. g.) something not "strain relieved" running to the engine and up against the engine mount or firewall,... causing a "sound short" (and getting ready to fail in the future)

It really is amazing how little it takes to shake the plane.

Read about a Reno racer that spent a LONG time with a experienced crew, before they finally traced a problem down to a cover not sitting fair.

keep plugging and keep us informed,... as you can tell,... you have us stumped,.. and we need some answers..
 
I had a bad airframe vibration, primarily when I pulled the power back. ( RV 8) (Lyc O 320) Turned out to be the flywheel. It had " Experimental" only stamped on it. Nobody had ever noticed that before. Borrowed a flywheel from another guy still building his RV 7 and swapped. Vibration gone. Gave him his flywheel back, and bought a new one of my own. Weird!!:mad:
 
Just checked this thread out for the first time. I'd be looking at my prop flange. You don't mention where the engine came from. I'd be doubly suspicious of the flange if it were a used or rebuilt engine. Very dangerous if it is the flange runout for it could eventually snap the crank in two.
 
Just checked this thread out for the first time. I'd be looking at my prop flange. You don't mention where the engine came from. I'd be doubly suspicious of the flange if it were a used or rebuilt engine. Very dangerous if it is the flange runout for it could eventually snap the crank in two.

Brand new engine from Lycoming. Hopefully this isnt the issue..
 
Is it REALLY RPM related.. or is it SPEED related?

I'm confused that you had it dynamically balanced,... yet you have vibration,... seems to me it would have indicated and issue if you had that done. (vibration not able to be corrected). Does it shake "on the ramp" or only while flying?

So,... is it something else,...a.) wing/fuse -seal/gasket loose? (been known to scare the bejimminies out of folks, when it wiggles out and starts shaking) b.) seal between cowl and inlet ramps not "fair and smooth",.. and shaking with air across it c.) wing walk non-skid pad coming loose and shaking air/wing d.) your other tires were out of round,... how does the tail wheel look,.. any abuse to it causing out of round? (as you found out, .. out of round tires shake) e.) all the access panels on tight? sure? f.) what about the bottom of the cowling... any chance the FAB is rubbing or hitting at some point.... they are known to have some fit-up and tweaking required depending on engine, carb/TB, and cowling arrangement. g.) something not "strain relieved" running to the engine and up against the engine mount or firewall,... causing a "sound short" (and getting ready to fail in the future)

It really is amazing how little it takes to shake the plane.

Read about a Reno racer that spent a LONG time with a experienced crew, before they finally traced a problem down to a cover not sitting fair.

keep plugging and keep us informed,... as you can tell,... you have us stumped,.. and we need some answers..

I say RPM and not speed because if I quickly pull my engine to idle from cruise speed and power, the vib stops.

How about this for an update.. if I put my toes down on the floor at the base of the pedals, I feel a VERY strong vibration in my toes. Haven't felt this before because my heels are further back on the floor. Exhaust pulses?
 
I say RPM and not speed because if I quickly pull my engine to idle from cruise speed and power, the vib stops.

How about this for an update.. if I put my toes down on the floor at the base of the pedals, I feel a VERY strong vibration in my toes. Haven't felt this before because my heels are further back on the floor. Exhaust pulses?

I think you have a lead to follow here Matt. Do you have turn-down tips on yor exhaust pipes? If not, get a set (Vetterman has them) and see if it makes a difference.
 
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