Thread Tools
Oct 07, 2012, 12:22 PM
Registered User
Francesco's Avatar
Quote:
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.
Sign up now
to remove ads between posts
Oct 07, 2012, 01:03 PM
Registered User
Tuomo's Avatar
Quote:
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.
Oct 07, 2012, 01:12 PM
Registered User
Tuomo's Avatar
Quote:
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.
Oct 07, 2012, 01:16 PM
Registered User
Francesco's Avatar
Quote:
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.
Oct 07, 2012, 01:36 PM
Registered User
Tuomo's Avatar
Quote:
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.
Oct 07, 2012, 01:41 PM
Registered User
Francesco's Avatar
Quote:
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
Oct 07, 2012, 01:44 PM
Registered User
Tuomo's Avatar
Quote:
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...
Oct 07, 2012, 02:58 PM
mostly gliders
liukku's Avatar
Quote:
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
Oct 07, 2012, 03:20 PM
Registered User
Tuomo's Avatar
Quote:
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.
Oct 08, 2012, 11:22 AM
Registered User
RC-JG's Avatar
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 ?
Oct 08, 2012, 12:11 PM
Registered User
Francesco's Avatar
Quote:
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.
Oct 08, 2012, 02:45 PM
Registered User
Tuomo's Avatar
Quote:
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.
Oct 08, 2012, 03:17 PM
Registered User
RC-JG's Avatar
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 ....
Oct 08, 2012, 04:01 PM
Registered User
Francesco's Avatar
Quote:
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).
Oct 08, 2012, 04:05 PM
Registered User
RC-JG's Avatar
Quote:
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


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Sold Supra Pro-e Competition lite IBWALT Aircraft - Sailplanes (FS/W) 4 May 24, 2012 04:20 PM
For Sale Supra Pro Competition Carbon Lite, Bind and fly.$1800 Wetcoast Aircraft - Sailplanes (FS/W) 2 Mar 25, 2012 10:11 AM
For Sale Supra Pro Competition Carbon Lite, team plane Wetcoast Aircraft - Sailplanes (FS/W) 4 Mar 20, 2012 03:27 PM
Sold Supra Pro Competition NIB (ST and glass layup) RCPC Aircraft - Sailplanes (FS/W) 11 Mar 06, 2012 03:54 PM
Discussion Supra Pro vs Supra Pro Competition brentrob Thermal 9 Oct 08, 2011 01:30 PM