Originally Posted by RC-JG

Everyone - Do you have your ailerons set the same as your flaps on launch ?

Yes.
However, due to the different mechanical advantage in the linkages, flaps will be probably "blown up" more than ailerons.

Originally Posted by Francesco

That is not directional instability, it is one tip stalling earlier than the other.

Ok. But having real tip stall leading to snap roll is very uncommon with F3J plane. Very different from F3B.

Originally Posted by Francesco

Yes.
However, due to the different mechanical advantage in the linkages, flaps will be probably "blown up" more than ailerons.

This small video is from this summer. Don't mind the music. Take a look at what happens at 23-24 seconds when I throw the plane.

laippaelokuva (0 min 37 sec)

Flap flex is alarming. This was in almost zero wind with good servos (DS3288) and not too sloppy linkage. Ailerons have obviously much less flap.

At the end of long launch you can also see change of launch camber. Normally I do this at much more early stage, maybe 1-2 sec. Using 2 stage camber improved my launch and made it more adaptable to variable conditions.

Originally Posted by Tuomo

Flap flex is alarming. This was in almost zero wind with good servos (DS3288) and not too sloppy linkage. Ailerons have obviously much less flap.

Yes, that's what usually happens. Slop in linkages is typically not a factor. One of the problems, as someone on RCGroups pointed out, is that we generally use very thin gauge wiring, and so the servos "thirst" for current cannot be adequately quenched.

Originally Posted by Francesco

Yes, that's what usually happens. Slop in linkages is typically not a factor. One of the problems, as someone on RCGroups pointed out, is that we generally use very thin gauge wiring, and so the servos "thirst" for current cannot be adequately quenched.

This paticular plane has robust (and heavy) wires.

The video was taken at the end of long flying session. And I use simple 4 cell eneloop rx-batt. With freshly charged battery it might have not looked quite so bad.

Originally Posted by Tuomo

This paticular plane has robust (and heavy) wires.

The video was taken at the end of long flying session. And I use simple 4 cell eneloop rx-batt. With freshly charged battery it might have not looked quite so bad.

Oh good for you!
Then you must conclude that your servos aren't simply up to the task

Originally Posted by Francesco

Oh good for you!
Then you must conclude that your servos aren't simply up to the task

I think whole F3J community is looking for better flap servos...

Originally Posted by Tuomo

I think whole F3J community is looking for better flap servos...

Would be interesting to see what it looked like if you used LiFe instead of NiMh?
Have stopped using NiMh and decided that all my gliders to work with LiFe, in one way or another. Uses multiple solutions today but it's probably just a matter of time before all vendors have high current servos.

/Ville

Originally Posted by liukku

Would be interesting to see what it looked like if you used LiFe instead of NiMh?

You are right. I am very conservative on running servos at higher than recommended voltage. And regulators are just one more thing to go wrong... When I find a good high voltage servo setup (all 6 servos), I will go immediately to LiFe.

Evening Everyone,

Just did some more work on the Supra,found 1 servo horn connection to have a small amount of play on 1 of the flaps so sorted that,set the camber at -2,and it the next day or 2 getting a proper CG jig to check that.

Will having the same amount of launch angle on the ailerons as the flaps tend to make it tip stall more ?

Originally Posted by RC-JG

Will having the same amount of launch angle on the ailerons as the flaps tend to make it tip stall more ?

I don't think so, provided that you use "split" differential on the ailerons during launch.

Originally Posted by RC-JG

Will having the same amount of launch angle on the ailerons as the flaps tend to make it tip stall more ?

I am 99% sure that you can carry more line tension without tip stalling, when ailerons and flaps are in line. Wing just works better. And drag is small compared to large flap camber and small aileron camber scenario - > faster speed.

Maybe (just maybe) having radical camber in tip section can provoke tip stalling. But then again, I do not know any modern F3J plane that has nasty tip stall tendencies. You get plenty of warning (directional unstability) before it really bites.

Tuomom - At the moment i've got 15 degree angle on the flaps which i think i am going to reduce it to 10 degrees on flaps & ailerons - once i've rebalanced it i can then check the tow hook position then should be good to go again ....

Originally Posted by RC-JG

Tuomom - At the moment i've got 15 degree angle on the flaps which i think i am going to reduce it to 10 degrees on flaps & ailerons - once i've rebalanced it i can then check the tow hook position then should be good to go again ....

10-degrees deflection seems good to me. I am using quite an aft towhook position (maybe 1 "click" before the aft limit), but with substantial amount of down elevator preset compared to my cruise mode (about 1.5 degrees, and my CG is 104 mm aft of the leading edge).

Originally Posted by Francesco

10-degrees deflection seems good to me. I am using quite an aft towhook position (maybe 1 "click" before the aft limit), but with substantial amount of down elevator preset compared to my cruise mode (about 1.5 degrees, and my CG is 104 mm aft of the leading edge).

Sounds good to me i will give it a go