Can anyone tell me why my AJ wants to snap right with full elevator. 70" with dle 30. plane flies great holds lines with virtually no mixing...

the only demon I keep seeing is when doing a loop or trying to pick up a sharp upline the plane wants to snap right... instead of pulling straight up it rolls a 1/4-1/3 to the right and pitches off vertical to the right 15-20 degrees.

Its quite consistant with this... and bugs me the most when finishing a loop or trying to square something off... is this a mixing issue, cg, surface, servo issue? kinda confused on how to fix it.

I'm assuming its stalling at high g load... but Ive had planes that you can pull as hard as you want and they don't kick out like this...</p>

Couple things to check.
Lateral balance, equally matched aileron servos, equal throw, solid linkage.

ill have to check the lateral balance...   the servo's are very very close ... my left elevator servo seems to have the very slightest hesitation at the very top end of high rates to match the right side...  but i could only notice that when I had 3 foot extensions on the elvators to make sure everything was lined up perfectly.   linkages are solid.   literally required no trimming.

it will still happen if I gradually bring back the stick more and more until all of a sudden it just snaps to the right...

... your on the wrong forum for 3DHS you should take your question to the forum where AJ and the other 3DHS pepole hang out

did Imiss the sign? thanks for the help

Its likely a combination of things that are applicable to all makes and models not just 3DHS

Have you checked your incidences? happy with the CG? where is it? Servos need to be tested under load, a no load test is not enough. I would think one EL servo or linkage is not 100%

Its a tested design, its likely something that can be pin pointed fairly quickly.
Yes the other board will likely give feed back at 15X the rate here.

It sounds like you just have too much throw and maybe along with an aft CG. Try backing out some throw just until it wont do it. This is a fairly typical high speed stall caused by exceeding the wings useful AOA for that particular airspeed. For 3D you would actually use more throw but at a much lower airspeed along with being in a stalled condition anyways. Usually for non 3D aerobatics one would not need more then 20 degrees of deflection.

high speed stall/snap is going on....even the best 3D planes will experience this with the exception of foamies and super light electrics


next time try doing a move called the wall make sure you have max elevator(3d rate 45 or more degrees)
fly level at about quarter throttle chop the throttle and apply full elevator.. if you arent fast enough and/or dont have enough elev. throw the plane WILL snap roll.

there are moves where too much elevator will cause a snap too.... such as when doing a loop or an immelman turn... it usually happens at the top of the immelman or the loop

thanks for the info guys.  

and maybe thats all it is... It will do it when I'm not on 3d rates... but I guess I do still have quite a bit of throw even on low rates.... and running like 30% expo.

just trying to get everything balanced  but I'm not seeing a major mechanical flaw... I'm going to check the servo's under load tonight.  how much force or weight do you put on the surface to accurately test the servo's

what kind of elev servos are you using

I bought the plane before I had done a lot of research on the quality servo's guys are running on this size and larger airplanes...

It came with Power HD 1501mg servo's all around... and some crap servo on the throttle. the servo on the rudder wasn't working so I put a hitec hs985mg

after further inspection and testing the elevator servo's under load the servo that was slightly slow.. became noticably slower. and the elvator on the right developed some sort of strange gitter. Needless to say Ijust ordered 4 more hs-985's for the plane. so I'll have those in this weekend and give it another try. I know they arn't the best of the best servo's ... but they should do the trick for the budget on this plane.

next plane I buy used I'll do a little more research on the servo's expecially if I jump to a 50 or 100cc

are you Y ing the EL servos or each has its own channel mixed together? what flight battery?

each is on its own channel and mixed. running a 6.6v 2400mah life battery I believe... one for ignition and one on servo's

So im guessing Nitro wing's battary type questions have not yet yeilded a fix to your orginal issue

Why don't you try posting in the 71 slick thread ??? or the fantaic thread ?? where KM or Noll hang out chance's are they would offer up more infomation.... Joe is on that thread to and Joe's Dad Sk8rob Beviens Doc many many 3DHS guys ...


and Just wondering why did you put duel servos on the slick it comes set up for single ....

Actually the opposite I think nitro wing told me what I needed to know. under load I am running into problems with the servos. I think its is cheap servo's. I wasn't aware the slick was set up for a single servo. I bought it used and this is how it was set up.. I assumed thats how it was supposed to be.

cg seamed good... just slightly behind the wing tube.

like I said plane flew great... this was the only issue I could find with the flight time I have on it. I was also unaware there was a specific 3dhs thread

really ? normally that would be Blow back and and blow back would result in the opp set of a snap onless only one servo was in blow back and the other was not do you have a watt meeter that you can load test the servo with ?

what would you expect the airplne to do if the left hand elevator was slower than the right under load. I'm sure I have a meter somewhere. my new servos will be here this morning and I plan on flying it again this afternoon or this weekend.

I hope the servos fix your problem. i have been following this thread because a had a Funtana years ago do the same thing. The only fix I ever found was to run the CG 1/2" behind the range. It was a 3D machine but precision went out the window. It also turned every landing into an adventure. I had to harrier it in every time.

david

well it definately wasn't that bad.... its really the only bad quirk it seems to have.

It didn't even want to drop a wing tip in a full elevator stall... just rocked a little.   first landing I had on the plane was a dead stick. ( engine was a little lean)   and it was smooth and pedictable all the way around.

no matter what the servos will be an upgrade from what is in it currently so I'm anxious to try it out.

I agree the servos need to go no matter. Another strange thing mine did: Full throw elev loops would make it snap/high speed stall. Loops with 75% of the max throw, would make the loop the shape of a stop sign. It's like it was stalling and catching all the way around the loop, if that makes sense. BTW my elev halves were joined in the center, so it was not a weak/strong servo issue. Lateral balance did help some, but not cure the problem.
I'll be watching with great interest to see how it handle the upgraded servos.

david

honslty that's a Funtana for you, they have known flight quarks

Hope it flies fine after the upgrade.

Zach
The simple batt questions was asked to make sure its not low voltage, capacity or old, which will crap out under quick, full load.
ALL info is important to help identify or pin point problems, as in any aircraft issues, full size or RC. Could be 10 other things too..
Its called helping out, not just tossing opinions out there, get it?


repsol83
There is no specific thread on this plane on this board, that I am aware of, its on other site all together.. A board that is active an informative.
Constant referance and suggestions to it are likely against moderator and site rules.

RCU is not as active as usual, but there are some members that have credible input and are well respected.

so Nitro wing your saying a battery brown out or weak power would cause a snap at the top of a loop ? sound's like crap to me ...... to me that would be more mushy and slow servo speed and or blow back ,, but hey what do I know, logically you would think if the battery went weak you wouldn't be gain more defecltion its more likely you would be losing deflection and it wouldn't account for uneven deflection .. I'd be wondering what's up with the duel elevator servo set up seeing someone changed 3DHS original set up and most of the time there set up is spot on , I'm beating this guy bought someone else's problem.....the slick is a great flyer I think we can all agree there, I fly the same plane and i knew something was super funky and I know the best bet of finding good information is the other forum .... I kinda don't like the fact that you fire blank information and what i consider misinformation out there , when a better suggestion was already Gaven .. and I'm pretty sure you don't even fly a slick do you ?

Just covering some of the possibilities, dont care if you agree or not.
Seems you offend more people here, than actually help. Ever notice?

it's aimed at you .. not him .. I'm sure he went out and bought new battery's now hes good .. or did he just wast time money and focus on some crap not relevant , do to the so called experts