Comp arf Superextra crash

[Doc. insane]

Hi guys,

A friend of mine crashed his superextra yesterday after only ten flights. The right aileron was suddenly torn off the right wing, while flying at low speed in a straight line at medium altitude. It was clear this failure was not caused by flutter since the gear was all brand new and made with the supplied hardware from the kit. The servo’s running the ailerons were HS5645MG’s @ 6V. After investigation of the crash site it was clear the crash was caused by a production error of the aileron hinge. The aileron was torn off backwards beginning at the hinge. ( see added pictures)

Does anyone has had the same problem? He would like to have a replacement for this plane since the crash was clearly not his fault. I personally think there is a need for a glasfibre/epoxy reinforcement to prevent crack initiation and propagation. I don't know if this sort of production error has already occured, but if yes I think comp arf should reconsider there production methods concerning these hinges.

Who should I contact at comp arf concerning this matter?


any help would be greatly appreciated. !

Best regards

[FastnLow]

I never did like how comp-arf set up the aileron servos on the super extra, there should be an inboard and out board servo. There is too much potential for twist and flutter as well as point loading all the servos power to one control horn, an outboard servo may have held it together enough to get it down or kept it from failing at all. Just a thought. My condolences to the owner, that sucks man!!

[reyn3545]

Isn't that a ball link I see on the Aileron side of your pushrod? Did your friend have 2 control horns on each link or just 1?

[TheTank]

5645s in a superextra??!??!!?!?!

[Rolling Thunder]

So it had 300-320 oz of torque on the aileron. Not much on an 122" wingspan plane. Flutter can cause the top skin to separate from the Rhoecell foam.

[thinkitsntillegal]

Is it ok to run the equivalent of 1-8611A enough for an aileron on an airplane like the Super Extra?

[DKjens]

Like The Tank and RT said, 2 x 5645MGs on each aileron on an SX is a disaster waiting to happen. Not only are they not strong enough, they center like crap and they develop massive amounts of slob. I will almost bet anything that Comp-ARF will not accept responsibility for this mishap, it is very simple, owner/builder did not follow instructions from manufacturer.

[wmat7039]

	Quote: Originally Posted by FastnLow
	I never did like how comp-arf set up the aileron servos on the super extra, there should be an inboard and out board servo. There is too much potential for twist and flutter as well as point loading all the servos power to one control horn, an outboard servo may have held it together enough to get it down or kept it from failing at all. Just a thought. My condolences to the owner, that sucks man!!

I will definitely disagree with you here. In my experience after having flown a Super extra for 3 solid years in IMAC competition & having 774 flights on my Super Extra she performed admirably during the period. I have NEVER had any signs of flutter on it. I also never experienced any "twist" since the structure was stiff.

I flew with 2 8611A's in each aileron and was very happy with the performance. After those amount of flights I sold the aircraft to a friend here in Georgia & he has it now going 2 more years. I just saw him at the Joe Nall & he is still very happy with his Super Extra & yes...it is still alive & flying well.

So...the possibility of the person above using inadequate equipment is a factor in what he experienced with his Super Extra.
Wayne

[JohnVH]

So an aileron fell off, what made it crash exactly?

BTW, my 3.3m comparf yak has the same hinging/servo setup, and that works flawlessly.

[Rolling Thunder]

	Quote: Originally Posted by JohnVH
	So an aileron fell off, what made it crash exactly? BTW, my 3.3m comparf yak has the same hinging/servo setup, and that works flawlessly.

I would guess panic made it crash. It should be landable with the aileron tore off or hanging.

I agree with Wayne The triangle box structure of the comp arf aileron is very stiff. It should not twist under normal loads.

[reyn3545]

I see the ailerons apparently have 2 control horns per servo... ignore previous post!

[Vic3D]

	Quote: Originally Posted by Doc. insane
	Who should I contact at comp arf concerning this matter?

You shouldn't.

5645's in a 3.1 meter airplane? Only 2? There's your cause. Sorry to break it to you, man, but those are not enough by any means. Maybe if it was three of them. But 2 is not good. 40% airplanes need a minimum of 600 oz per surface. 3 5645's would give you 540 oz which would WORK, but only 2 gives you just 360 oz.... That's the flutter recipe.

Hope your buddy gets flying again..

[rdgood]

YEP,

Ya don't ever skimp on servos on a plane like that... Sorry to beat on this..

The aerodynamic loads are way too high for just two 5645's.. its a wonder that both sides didnt blow up. The next question did you use 4-40 push rods or titanium??? I saw a friend of mine actually bend the 4-40 rods on his super extra...

So YES Abso-fricken-lutly you will always be flirting with disaster if you run average servos on a plane of that size!!

If you rebuild PLEASE do yourself a favor and go with two 300 plus inoz servos with metal gears!!!

I have seen this on several occcasions... some folks just don't understand how much energy can be transfered into the aileron at the onset of flutter!!

Ronster

[jongurley]

Should have been two 5955 hitecs or two JR 8711's,,, that is cheap insurance,,

[Yella Propella]

No matter the problem, its still terrible to see a crash like that.