blcargen

Hi everybody,
I just finished putting together the Extra 260 27% by Hanger 9. The build went very well. This is an easy plane to build. It appeared to be constructed of good quality balsa and plywood. The madian flight was not as sucessful as the building was. After a smooth take-off and a gental climb out I made a couple of trim passes. On the last pass I cut accross the field and thats when things went South. To backup a little Hanger 9 recomends that you put servos with 80 oz/in of tourque in the wings, one for each half. I used HiTech HS-6985HD servos with 172 oz/in of tourque each. Well, during the first flight I was setting the trims when the plane developed a severe flutter in the wings causing the plane to crash. The plane was a total loss. Has anybody else had any problems like this with this airplane?

Fletch124

My Feedback: (7)

Sorry about the crash, that is one sweet plane by the way. Thats really weird. Can you give us a detailed description of exactly what happened?

WELCOME TO RCU!!!!!!!!!!!!!!!!!!![sm=RAINFRO.gif]

blcargen

Fletch124:

You allready know what the plane is so... The engine is a DA-50 turning a MSC 22/8 wood prop. The prop was balanced prior to the flight. The servos in the wings were HiTech HS-6985HD with 172 oz/in of tourque, Hanger 9 recomends 80 oz/in or better for the wings. The DA-50 was mounted via DA's recomendations. I performed a detailed range check with and without the engine running. The range check was much better than ecpected, 175' +. I double checked that all control surfaces were moving in the proper direction and did a short taxi run. The Extra 260 taxied well so I took it to the downwind end of the field and turned around for take-off. I thrttled up slowly in about 20 feet the tail lifted. I pushed the throttle to full and gave it a little up elevator. The plane rose slowly and quickly reached flying speed. I throttled back to half throttle and began checking the trims. I did a couple of trim passes at half throttle. The elevators required one click of up trim and the ailerons required two clickes of left trim. Everything was going well so I setup to do another trim pass. When I turned onto the base leg the wings began to flutter violently! I immediately throttled back to idel hopping that the flutter would stop and I could land, but the flutter was so violent that both aileron servos stripped and were inefective. All I could do was apply rudder and keep the plane away from the pits and steer it in as flat as possible. Unfortunatly the wing was damaged to much and it tip stalled and came in on the engine and left wingtip. When I walked to the wreck I immediately noticed that the wing tube looked as if it had sheered since it was not bent but looked as if it tore in a twisting motion. The fuse where the wing attached to the plane was broken in front of and behind of the wing. This led me to believe that the wing flutter had toren the wing from the rest of the plane. I spoke with the guys that were at the field at the time and they said that they had never seen a wing flutter, yes the entire wing, like that before. They were amazed I could control it as well as I did, as was I! Well Fletch124 that's as well as I can remember the events of Saturday. I plan to contact Horizon Hobby tomarrow and see what they have to say. What do you think?

Thanks for your input!

50%plane

My Feedback: (5)

Sorry for the crash. The 260 is a really great plane. Did you seal your hinges? What prop did you use?

blcargen

Woops,
I did seal all the hinges and I used a MSC 22/8 Wood prop. I balanced the prop prior to the first flight.

mgruenba

It could have been 1 of 2 things. Either a faulty reciever, or faulty servos.
I have had a case of a faulty reciever. I had a Seamasterand it came down in a spin due to a faulty 7 channel JR FM Reciever.

Fletch124

My Feedback: (7)

were you experiencing interferance at all that day? Do you have PCM? Alot of guys crash because the PCM locks up, I heard this yesterday from an other club member and I agreed with him. I have an FM 6102, but anyways he was like I would rather fight it to the end then just sit back and watch. If the Rx isn't crushed or anything send it in. Were any of the electrics in another crash before this? A pushrod could have come off on one of the ailerons.

JoeAirPort

My Feedback: (41)

Those are Karbonite servos, and they strip gears on giant planes regardless of the torque rating. I had the same exact thing happen on a 25% CAP232 with HT 635 servos. Loc-tite on Karbonite servos is a no no, not sure if that was used on the screws. As I posted on a thread yesterday, I will never use Karbonite servos on a giant plane again. Hitec gave me 4 free 5645's to help me out with my loss. I had to buy a new $150 wing and a $40 new cowling, $15 wheel pants. I was lucky enough to suffer very little fuse and no tail feather damage. That CAP is flying with the 5645's and they work awesome.

blcargen

Fletch124;
I was not experiencing any interfierence at the time of the flight or any time after it. I use a JR 8103 PCM radio it did not go into PCM lock-out. and the push rods were intact after the crash. I thought about that when it happened but it was not the case. I allways use new electronics in all my new planes. I sent it into Hanger 9 today to see what they have to say. I am defanetly going to a metal gear servo in the next one!

kregan

First let me say sorry for the loss... even worse that you lost
the plane on it maiden... I just lost my first large plane, a 28%
Edge on Friday, pictures posted on this forum.

Plastic gears are a big no no in large aerobatic planes... I would
never use anything but digital metal gear servo's. I used 5945MG's
on my 28%. I am surprised Hanger 9 did not recommend better servo's
for that plane. I would imagine a DA 50 would pull that plane around
pretty fast.

blcargen

I won't be using those servos on any large planes again![:'(] I am going to use HS-5645MG on the ailerons. Do you think they will be a good choice? At 6 volts they have a tourq rating of 180 oz/in. I took the DA-50 to Desert Aircraft to have it looked at for any damage, I should hear from them by the end of the week. Yesterday I called Horizon Hobby and talk to their techs, they asked if I would send the plane back to them so they could inspect it. I hope there arn't other people having trouble with this also!

P-51B

My Feedback: (5)

Not meant to insult you or anything, but did you remember to put the wing attachment bolts on from inside the fuse? The description sounds like one of the wings was not tightened down.

blcargen

No insult taken. I thought that one may have come loose and that was the first thing I checked when I got to the crash site. Both were tight.

cstevec

My Feedback: (1)

I am flying my 260 with Futaba 3050 digital MG servo's in both ailerons. During the first dozen flights I didn't have the ailerons sealed but never had a problem with flutter or anything else. Then I sealed the ailerons. Now whenever I fly the plane over 1/2 throttle, I can see the ailerons doing a very minor flutter. Don't hear anything but you can see it. Hasn't caused a problem so far but I am at a loss as to what is causing it. I am going to change the reciever and see if that makes a difference. If not, then I'll have to change the servo's. There is 0 slop in my setup and all of the gear is new so I am really at a loss as to the problem.

Sorry for you loss, it's a great flying plane.

terminal velocity

blcargen, did you use ball links or standard clevises on your aileron linkages? I think many guys will agree that clevises provide too much slop for a plane this size. This could explain what initiated your flutter. Then once the flutter began the karbonite gears in the servos couldn't handle it and completely let go. BTW, for a plane that size 5645's should be good all the way around (at 6 volts). You may want to go with something a little bigger on the rudder though depending on their torque recommendations.

JoeAirPort

My Feedback: (41)

An 8611 on the rudder would be best but a 5645 would cut it. It just may not have as much authority since it will not hold position like the 8611.

hogflyer

blcargen - sorry about your loss. I recently lost my Astrohog due to elevator flutter.

I've noticed on a lot of large scale models the ailerons and elevators droop when the plane is static on the ground - no doubt to the weight on the control surface? Is it common practice to staticaly balance the control surfaces with lead counter weights on large scale? Full scale aircraft have strict balance requirement for the control surfaces to prevent flutter. Should this be a practice to be applied to large models to help prevent flutter?

Swager

My Feedback: (1)

Any crash photos??

Flyjets

My Feedback: (51)

Sorry About Ur Loss

If I had to guess I would say the Flutter was caused from the Servo stripping it's gears.

Check the servo and I am confident U will find there stripped. Having all that Torque doesn't mean anything if the teeth don't last.
Please report back on the servo arm teeth and the servo output spline.


The fellow who was asking about FM a Giant Gas airplane should never be flown on anything other then PCM and the Fail safe needs to be programmed properly. Going into Fail safe doesn't mean your going to lose your machine a receiver can go in and out of Fail safe and still return home safely.

Ian

P-51B

My Feedback: (5)

Check out post #900 at the bottom of this page in the 3d forum; http://www.rcuniverse.com/forum/m_28...page_36/tm.htm

How did your wing tube look?

cstevec

My Feedback: (1)

Actually, I would tend to believe the flutter caused the servo gears to strip & not the other way around. Big question is, "What is causing the flutter?". I am using Futaba 3050 digitals with metal gears. Yesterday a flying buddy was at the field with a Goldberg Matrix? Nice looking plane but he had the Futaba digital 3050 servos in the wings. He said the plane fluttered and stripped the gears in the original servo's so he upgraded because of the metal gears. When he was flying it I saw at high speed (about 3/4 throttle) the ailerons started to flutter again. After landing we checked it out & there was no slop, loose hinges, broken gears or the like. Surfaces sealed & all. I'm wondering if there may be a problem with the 3050 digitals? I know the planes are vastly different but the symptoms were identical. He originally had cheap Futaba 3004's in the plane so I discount that because they aren't nearly enough servo for an aerobat like he's flying.

hot shot 260

hey i have the same airplane i am just finishing it i will let u know on my first few flights how it goes sorry to here yous crashed it really is a pretty bird.

hot shot 260

also did u have the hinge gaps sealed?

50%plane

My Feedback: (5)

blcargen

Thanks to everyone!! All your comments and suggestions are a big help. Please keep them coming! I am trying to answer all questions as soon as I can. Thanks again.