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May 18, 2008, 09:57 PM
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Help!

Super Ava Out Of Control


When I fly my super ava,(with 6oz. of ballast),when I turn left or right it spins down at a 45 degree angle. I give it opposite rudder and nothing happings. I have to give it full down to recover. The CG is correct(4 inches) back from leading edge and everything is tight. If i am am flying it too slow, do these things spin down out of control ? This thing is not fun to fly. I bought it new. Any suggestions would be appreciated.
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May 18, 2008, 10:05 PM
Registered User
Define 45 degree angle. Bank?

Sounds like maybe the cg IS too far back. Or there's slop.(I know you said there isn't). Or not enough rudder throw? Or you're flying too slow and there's washin in the wing which you haven't ironed out?

I have not flown a Super Ava, but my regular one has quite nice handling and doesn't do anything strange.
May 18, 2008, 10:47 PM
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Thread OP
The CG is what is suggested. The 45 degrees is towards the ground, spinning! It spins down the same, left or right,with full opposite rudder. I have alot of rudder throw, at least 3 inches each way. Thats about twice what is suggested.
May 18, 2008, 11:32 PM
Registered User
Hmm... I would say that you're trying to fly it too slow (and here I am giving advice about a plane which I haven't flown yet (note the "yet", I've just recently received my new Super Ava...)).

Do you have any up elevator trim, or are unconsciously putting in up elevator whilst flying?

If you have it in the air, and put in some down elevator, what does it do? Tuck under, do nothing, or pull out of the dive?

- bec
May 19, 2008, 12:42 AM
Registered User
Thread OP
I did'nt have a chance to test dive it. I had my hands full just getting it down in one piece. I may put a half ounce more of nose weight, a little more down trim and try again. I probably dont need the weight, but it might help it move a little faster and settle it down for the next flight. As for giving it up elevator while flying, I probably gave it a little up as I started to turn, no more than usual though.
May 19, 2008, 08:59 AM
W0X0F
IBWALT's Avatar
Gary, your experiences with the Super AVA are not unique. When I first got my SA I thought that it was the biggest pos that I had ever owned or flown. I even came real close to dumping it and buying something else. That is until I added ballast and moved the c/g forward.

On the KC website 4" or 100mm is the recommended c/g. Well 4" is not equal to 100mm. It is about 1/16 of an inch further back and as far as I am concerned 100mm is to far aft of a c/g for the SA. A recommended c/g is just a recommended starting point. It will get you in the air but then it is up to you to tune the plane to your flying style. Anyway the KC recommended c/g for the SA is way to far back for anyone but the most skilled r/c sailplane flyers. At 100mm the SA is far from pitch stable and requires 100% concentration to fly. The slightest nose down attitude will only lead to additional speed and more uncommanded pitch down. As in tuck under. The SA will not recover on its own. This c/g (100mm) may mean that you can detect the slightest lift but makes the plane very difficult to fly. Especially at a distance or directly overhead and a real hand full if your not experienced flying planes with a c/g this far back.

Another thing that I did not like about the SA when I first got it was that I thought that the rudder was not large enough because I was having some directional control issues. The plane just did not want to turn when I wanted it to or if it did turn it was very sluggish. I thought that the SA had some real problems. But after a month of flying and tuning I found out the problem was me. I was trying to fly the SA to slow. A little down trim and the SA was flying and turning better. But it was still getting pitched around by every little puff or gopher phart. So I added a ballast tube and 9 oz. of ballast and the performance of the SA got even better. So now I fly with 9 oz. all of the time, regardless of how light the wind or lift may be. I can fly it without ballast if I want but to me the SA has to light a wing loading and requires a little weight to make it a better performer.

I would suggest a couple of things to you to solve your problem. First I would move the c/g forward to 95mm then start flying it just slightly faster, and increase your ballast to 8 oz. Try flying it like this and see if the SA starts flying a little more to your liking. If it still does not want to fly right I will give you $150 for it (if it is still in one piece).

Walt
May 19, 2008, 12:21 PM
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I might sell it to you for 150.00, but I think freight to texas is about 750.00!(Everything in Texas is big). Thanks for your imput. I think I'm going through what you went through with yours. I will try your recommendations and see what happens. I'm sure it will help. Thanks again, Gary
May 19, 2008, 12:32 PM
I just wanna fly
slozuke's Avatar
I totally agree with Walt. When I first started flying my SA I didn't like it much. It wallowed around the air, didn't have very good turn response and wouldn't penetrate a fart.
I added 6 oz of permanent ballast in the belly, that's in addition to the capacity of the ballast tube. I also moved the cg forward with about 1/4 oz of nose weight. I didn't change any of the control throws and now it's a much better controlled beast. Be careful when flying it slow as the control surfaces become pretty sluggish. It'll float but the responsiveness is a bit slow.
The biggest problem I still fight to get adjusted properly is my spoiler to elevator mix. Keep trying and you'll like the SA once you get everything adjusted.
May 19, 2008, 12:44 PM
Registered User
Andy W's Avatar
If I am not mistaken, isn't the LE of the AVA (and S-AVA) relatively straight compared to the TE?

If that's the case, doesn't the larger center panel on the S- mean that the CG should not be the same as on the regular model, but further forwards in any case?

Just thinking out loud..
..a
May 19, 2008, 03:12 PM
Registered User
It may not apply in this case, but the newest issue (June) of RC Sportflyer magazine has an article by Don Bailey that discusses how having the CG too far FORWARD can cause a glider to fall into a graveyard spiral. This could happen on even a shallow banked turn.

The Don Bailey article also talks about the problems associated with having the CG too far BACK.

Has any expert read this article and care to comment?

-John Elliott (Seattle)
May 19, 2008, 04:01 PM
dare to be dull
bigjohn's Avatar
This sounds like it needs to be hand tested over a field of tall grass & soft dirt before putting it on a launch line again. That's after having a dependable person check the glider nose-to-tail for anything you might have missed.
May 19, 2008, 05:55 PM
Registered User
Libelle201B's Avatar
Quote:
Originally Posted by gary1201
When I fly my super ava,(with 6oz. of ballast),when I turn left or right it spins down at a 45 degree angle. I give it opposite rudder and nothing happings. I have to give it full down to recover. The CG is correct(4 inches) back from leading edge and everything is tight. If i am am flying it too slow, do these things spin down out of control ? This thing is not fun to fly. I bought it new. Any suggestions would be appreciated.
Luckily, IBWALT and others have been there with their SA's. By your description it seems pretty clear to me that you may be flying at the aft limit of the cg range (less stable) and also without enough airspeed. Don't forget that you need a bit of airspeed before you enter a turn or begin a turn to thermal. Starting a turn from just above or at stall speed is almost a guarantee of entering a spin, depending on the bank angle. The higher the bank angle, more speed required. Your sailplane needs full down to regain airspeed from the stall so that it can start flying again and you then regain control. Same goes for the rudder, that won't become effective either until you regain airspeed. To keep it simple, just add 1/2 oz of lead in the nose and put in a few clicks of down trim. I suspect you will see a big improvement.
May 19, 2008, 08:44 PM
ein flugel schplinterizer
seanpcola's Avatar
Glad I stumbled on this thread. I have been thinking of starting a S-AVA thread. Mine flies pretty good at the 4" mark but I have only flown it at dead stock weight. I flew a friends a while back with 12 oz. of permanent ballast and was much more pleased with his. Last night I installed a 14 oz. ballast rod in mine but have yet to fly it.

I will take all of this good advice.
May 19, 2008, 09:37 PM
Proud member of LISF and ESL
According to the Kennedy web site the Super Ava weighs around 44 oz and has a wing loading of 4.7oz/sqft. I think that is lighter wing loading than a Gentle Lady at close to twice the wing span. I could see that as being too light.

My regular AVA is 44 ounces for about 5.7 oz and it flies like a dream.

If you got the Super AVA up to about 56 oz it would be in about that same 5.7 oz range which is still very light. Based on the posts here, that sounds like a good target for this plane.

I don't have one, I am just interperting the posts in this thread.
May 19, 2008, 11:44 PM
Registered User
I don't think there's anything with forward cg that will be hard to recover from. However, I've seen beginners go into a turn, make it too steep, and then try to stop the descent with elevator. That doesn't work, you have to get rid of some of the bank with opposite rudder. And possibly a forward cg will aggravate that a bit. However, that's not especially a handling vice, it's just what happens when you use the controls incorrectly.

I've never seen a "graveyard spiral" from a shallow turn.

Basically, aft cg results in divergent behavior such as tuck under or pitching up to a hard stall. Forward c.g. gives heavy controls, and maybe a bit of pitch oscillation and a softer stall.

Not sure if I'm an "expert" but I've been flying rc gliders for many years.
Quote:
Originally Posted by jbeanelliott
It may not apply in this case, but the newest issue (June) of RC Sportflyer magazine has an article by Don Bailey that discusses how having the CG too far FORWARD can cause a glider to fall into a graveyard spiral. This could happen on even a shallow banked turn.

The Don Bailey article also talks about the problems associated with having the CG too far BACK.

Has any expert read this article and care to comment?

-John Elliott (Seattle)


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