What does flutter sound like?
 

Hi.

While flying my Hobbico Hobbistar 60, I've done a couple of high-speed (well, high-speed for a trainer) passes and another pilot said he heard flutter. All I heard was the prop and engine.

1) what does flutter sound like?

2) Is there a way to isolate it so I can be sure that is what I'm hearing?

RE: What does flutter sound like?
 

[link=http://jimsrc.com/t2.html#flutter]definition of flutter.[/link] just wiggle the control surfaces (all of them) and make sure they are fairly solid and are hinged properly. also, make sure the hinge line gap is as small as it possibly can be. I'm sure someone will chime in on how to tape the joints I personally, never have done this nor needed to. but still is good to know I suppose.

RE: What does flutter sound like?
 

Re: Sounds like:

Like a medium to high pitched buzzzzzzzzzzzzzzz. As if you had some covering material flapping VERY fast in the wind.

Think a lower pitched kazoo like sound.

Re: Isolate

Yeah risk doing it again...

What engine do you have in your trainer?

If you have an engine larger than recommended and/or with a higher pitched prop, you run the risk of causing flutter.

If you don't stop it immediately, you could see your plane disintegrate in mid air, almost as if it been hit by a missle.

There is a video somewhere around here of I believe it was Chip Hyde flying a Funtana with an oversized engine.

During what appeared to be a normal pass, you can see the Funtana come apart just above the tree line.

RE: What does flutter sound like?
 

Like that definition that Jim posted, it's usually a low-pitched buzz. As far as isolating it, that's not really possible because it's not something that you want to produce on purpose. Trust me, if you had flutter you probably will know about it before too long as it can literally destroy a plane withing seconds. If you think you have flutter on your plane you should land IMMEDIATELY and investigate for the cause of the flutter. You should not fly the plane again until you figure out what was causing it.

Ken

RE: What does flutter sound like?
 

fdfdfdfdfdfdfdfdfdfdfdfdfdfdfdfdfdfdfdfdfdfdfdfdfd fdfdfdfdfdfdfdfd!!!!!!!!!!:D

I hope this helps!

LT-40

RE: What does flutter sound like?
 

Thanks for the replies.

The plane was a RTF and came with an OS .65 LA engine [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXGHD4**&P=6]see it here[/link]; however, I've been told several times that I may be flying the plane a little too hard. On my high speed passes, I'll get a good amount of altitude, then point the nose straight down, full throttle and then level out near the ground so I'll have top speed as it passes me.

So the buzz of the flutter will be much louder than the normal engine sounds? Or does it take a trained ear to notice it? Or should it be pretty obvious?

There are small gaps between the wing and ailerons, but they were there when I first received the plane.

RE: What does flutter sound like?
 

On my Patrick Edge 540 it sounded like BBBrrrrrrrrrrrrrrrrr. A very nasty sound and you'll know it if you hear it!

Jim from Rometucky

RE: What does flutter sound like?
 

Yah think? :D


Not necessarily, sometimes it's much softer.


One you recognize it, you'll thereafter know it.


This is pretty normal.

You have a trainer, not a speedster.

I'll bet it's picking up plenty of speed on those downlines.

You should be chopping the throttle whenever you point the nose down.

Most trainers do not have speed brakes.

:D

RE: What does flutter sound like?
 

Sounds like a vibrating drum and the sound varies from plane to plane. Large open frame panels will resonate like a drum head and may have a snare snap to them. Solidly built structure will have a lower-pitch buzzing sound. If your engine is screaming you might miss flutter of a small surface. Furthermore, just because it didn't flutter this time doesn't mean that it won't next time. Thirdly, if it does flutter and survives, don't assume it will withstand it a second time, or a third, or a fourth.

I can pretty much agree with those warning you about your flying. Unless you have a well-tuned, solidly-built ship, doing that 100 mph stuff will eventually tear your plane apart.

Normal sport linkages and servos are too sloppy and one day soon you are going to fold the wing up on that trainer airplane doing full-throttle pull ups. don't mean any offense, but take some advice and slow it down until you get a better airplane.

N

RE: What does flutter sound like?
 

Uhhhhhh yeah, hope you have money saved for a new plane.... trainers sometimes do not like to be treated like that. Don't know about that model tho. But oh well, its your plane. I dont even do that with a plane that can take it. If you are going to beat on it like that, make sure you use new rubber bands no less than everyother flight........ trust me.

RE: What does flutter sound like?
 

As a bystander I have detected three audible components of a flutter episode:

1. The loud buzz others have described.
2. The bang as the aircraft (minus some critical component) hits the ground.
3. The "OH Sxxx" of the unfortunate pilot.

RE: What does flutter sound like?
 

LOL yeah, thatS about right. only diffrence is number 3. but its a toss up between yours, and or W T F !?

RE: What does flutter sound like?
 

I've seen a plane come apart in flight from flutter, and trust me there's usually not enough left of the plane to "bang" as it hits the ground. Usually pieces floating back to the earth. And the one that I saw nobody (even the pilot) said a word, we were all standing around with our jaws on the ground in amazement that a plane can come apart so fast!!

Ken

RE: What does flutter sound like?
 

A bad one can sound like when you were a kid and put a playing card or baseball card in the spokes of your bike. Riding fast...................

RE: What does flutter sound like?
 

Wanna go fast? May I sudjest this: http://www2.towerhobbies.com/cgi-bin...?&I=LXEUN4&P=7
Your trainer is to valuable for teaching yourself and others down the road to risk damaging it doing high speed dives that it was not designed to do.

RE: What does flutter sound like?
 

It's pretty easy to recognize. It is a buzzing sound as described earlier and it's generally the last thing you hear during the flight until the heaviest part of the airframe it's the ground. The wing may float down a few seconds later.
Turn the radio and reciever on and try to flex the control surfaces by hand against the force of the servo as it idles. If you have any slop or appreciable flex in the pushrods, it is possible for a trainer to suffer from flutter at extreme speeds.

RE: What does flutter sound like?
 

One point, if you even THINK you hear a flutter immediately chop power to idle and reduce speed as quick as possible. You might be able to save the plane. Land and investigate immediately.

RE: What does flutter sound like?
 

If you have any difficulties hearing what it sounds like,you won't have any problems seeing what it looks like:eek:

RE: What does flutter sound like?
 

It's the sound your plane makes just before it disintegrates in mid-air. You can avoid flutter by taping your hinge-lines or MANAGING YOUR THROTTLE. Either way is sufficient. I do both.

I have literally fluttered a plane in-half. Just remember that a trainer is not likely to attain flutter speds, no matter what engine you can FLY it with. If your plane were fluttering, you would surely know it, and this thread would never have occured.

RE: What does flutter sound like?
 

It sounds like money

RE: What does flutter sound like?
 

After enough description covering the sound of flutter I'd like to add one thing. Taking for granted a reasonable linkage, sealing the hinge gaps with a piece of clear Oracover/Monokote/whatever brand you like is the single best anti-flutter device that takes about one minute per control surface to install.

A couple of experiences of mine. I had an Arrow, ~1980 patternship, fast flyer that had too soft torque rods and unsealed but very closed gap airlerons. First flight saw one aileron flutter and get ripped off, hanging by the torque rod. I managed to save the airplane, fixed the aileron (not the torque rods), sealed the gaps the way I should have in the first place, and never had flutter again.
A couple of weeks ago, I was flying a Synergy 90 3D and it had been twitching along the longitudinal axis (that's the roll axis) as if I had a defunct servo. I flew a few minutes, fast, slow, up and down, and after landing discovered that an aileron hard point had come loose inside of the wing. If any airplane will develope flutter, its an airplane with oversized control surfaces. I had properly sealed all hinge gaps prior to ever flying the airplane (its been a standard part of my building since the Arrow incident) and can say that it was that tiny strip of Oracover that kept the aileron from fluttering the airplane apart. I experienced no flutter even at high speed with a floppy aileron.

Lastly, sealing hinge gaps really helps aileron and elevator response and makes for a much more trimmable airplane. I even sealed the gaps on an Astrotrainer so that my guests have a more honest airplane to try (I like to share my hobby with friends). A roll of clear covering is enough to seal the gaps of a couple dozen airplanes.

Mark

RE: What does flutter sound like?
 

or possibly, "who's on my channel!" There's a guy at our field who seems to use that for EVERYTHING. :eek:

RE: What does flutter sound like?
 

If you've done this more than once chances are its not flutter.
Flutter does have the distinct sound everyone talks about, but usually the airplane comes apart before its recoginized.
I've seen flutter twice, once due to to large a gap, resulted in cracked hor stab, and once due to a failed servo, no damage but sure did buzz
is your covering tight? if you have a few wrinkles that maybe what he heard.
its your plane fly how you want but if you lose your trainer you will always miss it, most guys I know still fly a trainer every once in a while.
good luck

RE: What does flutter sound like?
 

Sort of like what a beautiful little sparrow being blown out of the sky but a 12 gauge.

RE: What does flutter sound like?
 

In this video, you can see a wing in a fully developed flutter, especially in the slow motion repeats.

http://www.youtube.com/watch?v=ENcIZVx-o9c

RE: What does flutter sound like?
 

I don't know what flutter sounds like, but an interesting sound that is usually made right afterwards sounds something like "oh damn!"

RE: What does flutter sound like?
 

BLE,
More often than not, a still picture, movie or video is worth a thousand words. You choose the right flick to show flutter!

Thanks,
Ernie
Sailplane

RE: What does flutter sound like?
 

I've got the same plane that makes the same noise you are talking about. I've flew it with that noise well over 100 times. It always happens in a high speed nose down atitude. Everybody said it was bad flutter. Well it isn't, its the front nose cheeks vibrating against the big long aluminum motor mount on that particular plane.


Ronnie

RE: What does flutter sound like?
 

Which I would immediately correct so as not to happen again because...

- It may mask the sound of real flutter.
- It indicates excessive vibration of a part
- It will cause excessive wear of the cowling

Do you have anti-vibration mounting in place on your cowling? e.g. the tubing over the screws, etc.?

RE: What does flutter sound like?
 

Ahhh, I ain't to worried about it. If I get tired of listening to it I'll just cut the cheeks off of the plane.

No anti-vib stuff on it, the plane comes with everything mounted solid on this particular model.
I fly this plane full speed every time its up with no problems at all. If it quits, it quits. I've been wanting to put that engine in something else anyway.

Ronnie

RE: What does flutter sound like?
 

I've actually had to epoxy the two wing halve back together twice already. I guess the stress has been breaking that bond. However, I love screaming down the runway shooting the plane straight vertical, then a quarter turn and watching it rocket into the sky. This particular trainer has a thick metal rod in the wing, so perhaps that is holding everything together. I'm building a Venture 60 kit currently, and there is no way I'll be attempted some of the same things I do with the trainer. The trainer is built like a tank compared to the Venture. There is probably twice has much wood in the trainer. The wing ribs are over double the thickness of the Venture.

Thanks Ronnie. Those cheeks do flap quite a lot. Even while on the ground, I'll throttle up on the test stand and the cheeks violently clap. I'm worried that one of these days, the fuel line from the high-speed needle valve to the carb is going to come off while in the air. I can see the left cheek actually hit it the fuel line.

I've also had some problems with screws coming loose on the engine mount and the engine back plate. There must be a lot of vibrating going on up in the air.

RE: What does flutter sound like?
 

Hi, My Four star 120 with a 25cc toro suffered from flutter last week. I went straight up with it until it couldn't climb anymore, pulled the throttle down came straight down with it and both ailerons fluttered!! It sounds like the trailing edge of a kite flapping on a windy day. I lost control of both my ailerons. So I had to land with the rudder! Found out one servo stripped and the other servo mount broke loose from the aileron hatch. I was lucky to land it in one piece. I will now beef up the aileron hatch mount and use metal geared servos. Lesson learned!

RE: What does flutter sound like?
 

It sounds like this: (Ahem) "WAAAAAAAAAAAAAAAAAAAAAAAPOP!hissssssssssssssssCRA CK!"

RE: What does flutter sound like?
 

Normally when you here it & say W T F it's T F L.