.46 UCD3D Flutter
 

Has there been a problem with the .46 size UCD3D and aileron flutter?

A friend brought his out to the field Sunday for the maiden flight. There was about a 10-15mph wind. After he took off and headed downwind everything seemed fine but when he opened it up and turned back into the wind ,straight and level, the ailerons started flapping violently and before he could back out of the throttle the flutter had ripped both the aileron servos completely out of the wing taking most of the covering from the bottom of the wing with them. He used rudder and almost got the thing down in one piece but caught a wingtip and the resulting 1/2 cartwheel broke the fuse in half.

We had checked the plane out on the ground and there was little or no play in any of the control surfaces and very little if any gap in the hinge line. He was using Hitec 425BB servos on the ailerons and had a OS 46FX on the nose so it surely wasn't overpowered.

When I say it fluttered I men it FLUTTERED! It was about 50-75 yards out and you could see the ailerons flapping like a bird. It only took a second or two before it tore the wing up.

Just wondering if this is something that is a known problem with the .46 UCD3D or if this was an isolated case.

RE: .46 UCD3D Flutter
 

I have the U Can Do 60 and never had that problem. Check the hinges real good for being secure. Otherwise I'd say that the sevos went bad and that does happen. Hitec wil repair them or replace them for free. But not your plane, Too bad, I found out the hard way too.

RE: .46 UCD3D Flutter
 

You didn't say what engine and prop he was using.

These light airplanes with huge ailerons are prone to flutter. They are not meant to be "opened up" unless they are going straight up or recovering from a hover. You can expect flutter if you fly fast and try to make a high speed sport plane out of them. They are designed to fly at partial power unless you need full power for a 3D maneuver.

RE: .46 UCD3D Flutter
 

i will say to fast a. 4 pitch prop would be around 40 mph . with the stock hardware junk that would do it . or it could be one of them with the bad wing.

RE: .46 UCD3D Flutter
 

I think Ed has your answer.

Eric

RE: .46 UCD3D Flutter
 

It had an OS 46FX turning an 11X6 Master Airscrew. It was flying straight and level. Didn't seem to be flying all that fast but it was headed into a 15MPH headwind. He had just throttled up to check for ironically..... flutter. :(

RE: .46 UCD3D Flutter
 

I am also in favor of Ed. I have personally fluttered the ailerons of a Pizazz. It was my fault for going to fast. I have watched others do the same thing with just about any of the fat wing, large control surface planes. From experience, you do not fly this type of plane fast. They're designed for maximum control at low or slow speeds. Anything faster is inviting disaster.

RE: .46 UCD3D Flutter
 

I had no problems with my UCD 46. Full throttle on a YS-63. Hitec 425's in the wing. Hinge gaps SEALED, and 4-40 hardware all around! They are not meant to be flown full throttle but I do a straight and level to check trim.

RE: .46 UCD3D Flutter
 

Just to blow your mind, the plane does not (feel) the 15mph headwind. I think what you were trying to tell us that the plane was going 15mph faster in the headwind WRONG.

RE: .46 UCD3D Flutter
 

polstery
Can you clarify your point about the 15 mph wind a little further?

If planes don't feel the wind wouldn't aircraft carriers be able to stand still and launch their jets?

Didn't the Wright brothers have some trouble flying without a head wind?

If the wind was blowing 100 mph and you were at full throttle just to maintain a ground speed of 0 mph wouldn't your ailerons know about that?

RE: .46 UCD3D Flutter
 

I need some elightenment also. It seems to me that if the plane was even stopped you would still have 15MPH airspeed over the ailerons.

I agree that these planes are not built to fly super fast, but straight and level with the recommended engine? It did have the supplied 256 aileron control rods. They are a bit flimsy and soft. If he is able to fix the plane I think 4-40 rods would be a good place to start.

RE: .46 UCD3D Flutter
 

I strongly agree Robotech! I don't use 2-56 anymore except on the throttle. Especially if I'm going to 3D! We do not want flex. Just to make you feel better, I put mine in... was on the deck, pulled to the vertical and 15' up my engine stopped. Immediate stop of forward motion, just flipped to nose down and hit square on the spinner. [&o]. I set it aside to be worked on later.

RE: .46 UCD3D Flutter
 

A guy I fly with had the same thing happen to his. He was flying straight and level at less than half throttle (.46 XLS), he was running maybe 25-30MPH and started getting flutter big time. He landed the plane and went over it with a fine toothed comb. Everything appeared to be perfect, so he took it back up. Same thing again, except this time it didn't come home in one piece. To this day, we still don't know what caused it. He bought another, but has yet to get it in the air.

I'm definately not trying to start anything here, but I think that as long as a plane is flown with the reccomended size engine, and is being propped to perform how the plane is meant to perform, the plane "should be able" to withstand higher speeds with no problems. If there is a chance that the plane can't handle higher speeds, and those speeds may not be what we would call "fast", maybe GP should put a warning in the manual.

Just my thoughts,

John

RE: .46 UCD3D Flutter
 

John, GP has warnings in the manual about this. The problem is few people read the manual, they just want to assemble from the pictures. If they do read it they don't beleave it.

Ed M.

RE: .46 UCD3D Flutter
 

Ed,

You have shed light on the warning issue in the manual for me, but, I still think the plane should be able to fly at least 25-30MPH without fluttering. Anything above that, I wouln't be so suprised to hear of flutter.

John

RE: .46 UCD3D Flutter
 

An aircraft flying in a steady state wind, not in contact with the ground (or the ship's deck in the case of the carrier) has no effect from wind except in its ground track. Aerodynamicly... it doesn't feel the wind.

Fly from the ground in a steady 40 mph wind... "WOW the wind's blowing the plane all over the place." Now same wind... same plane... you stand in a balloon gondola... the wind will seem to have NO EFFECT AT ALL! Its not the wind... its youre perception changing how you make the plane respond. Those circles that look constant radius to you on the gournd (if you are good enough to do that... Full scale, pilots of light planes have a hard time with "turns about a point" in a strong wind.), are a constantly changing radius aerodynamically.

The Aircraft carrier points into the wind for launch/recovery ops in order to reduce the ground speedrelative to the deck) required for take-off and landing. (also to eliminate cross-wind effects which would be a total pain when landing on the narrow "runway" hard enough to hit the "runway that moves in 4 directions" without the wind correction to ground track direction) Think of it as purposefuly spinning the earth in the best direction so that your runway lines up with the wind at your flying field. Now spin the earth a bit faster under tha atmosphere so you don't have as long a ground roll to gain flying speed.

The wright flyer required something like 25 mph airspeed to fly (when dry) the catapault could accelerate it to about 15 mph (maybe 18...) ground speed. if they didn't have a 10 mph (preferred 15...) wind... they couldn't get the required airspeed to fly. (the re-enactment, they had inadequate wind AND addded wieght from the plane being all wet. It didn't fly.)

A common kid's kite... flies nice if you have wind... no wind= no fly (unless you run a lot). Why? That string you hold is the motor. If the air is not moving in relation to the guy holding the string... the kite has no airspeed. More wind = more airspeed and more pull n that line (because the kite wants to go where the wind is going... the guy on the ground is exerting a force on the kite (acting as the motor)

**** that SHOULD make it clear... no ground contact... the airplane does not care if you have 0 wind, 5 mph or 50 mph wind IF the wind is constant. Gusts are a whole new story. (a longer one)

RE: .46 UCD3D Flutter
 

So, if the wind was blowing 100 mph and you were flying into the wind at a throttle setting to maintain a ground speed of 0 mph, are you saying that all that air flowing over the ailerons would have no effect on them?

Don't you have to fly at a higher throttle setting to make headway into the wind?

RE: .46 UCD3D Flutter
 

I can take my .60 size UCD3D and with a strong headwind almost stop it in the air and do snap rolls one after another with almost no forward motion. If the wind has no effect on the control surfaces how is this possible?

RE: .46 UCD3D Flutter
 

Thanks FHHUBER I just checked in and saw your post . I'm sure you didn't need me to tell you your right on. THANKS for saving me some typing Rocketman you seam to be having trouble with the difference between airspeed and groundspeed. No one ever said anything about control surfaces of course they work we are talking about AIRSPEED AND GROUNDSPEED. A common thing people do is to add the windspeed to the airspeed of the plane then look at groundspeed to confuse themselfs even more. Simply stated airspeed is airspeed regardless of windspeed and groundspeed. Lets say your plane stall at 5 mph (airspeed) and there is a 10 mph wind, when the plane stalls at the 5 mph (airspeed) the groundspeed ( the speed it looks like it going) will be 5 mph backwards but the plane still (feels) the 5 mph airspeed. And if we turn it around and have a tail wind the planes groundspeed ( the speed it looks like it going) at stall will be 15mph but the plane will still feel the same 5 mph airspeed. Thats as simple as I can make it. Hope it helps.

RE: .46 UCD3D Flutter
 

polstery,

Your point is well put but I believe most of us already understand that.
And yes somebody did say something about control surfaces, specifically the ailerons. The title of this string is ".46 UCD3D Flutter" and if you read the first three sentences in Robotech's initial post its all about the speed of the air over the ailerons and the resulting flutter. His friend's airspeed was obviously greater going upwind than it was going downwind because flew into the wind at a higher throttle setting.