HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Dec 06, 2014, 07:20 PM
Registered User
United States, VA, Norfolk
Joined Sep 2007
447 Posts
Have you tried reducing your elevator throw? How much exponential are you using on your elevator? Also, snap flap...even small amounts can make your elevator feel sensitive. It sounds like you have more than a small amount going on, but it is hard to know unless you measure how much your camber (flaps and ailerons) are moving with your elevator. BTW, what servo are you using for your elevator?
burke757 is online now Find More Posts by burke757
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 06, 2014, 07:32 PM
Registered User
United States, NY, Buffalo
Joined May 2013
1,348 Posts
Lots of questions... I'm not really sure I am sufficiently involved to answer them to the level required. Sorry.

There is no expo in my servo travel. I don't think my elevator feels sensitive.... the main problem is that the wing seems to tip stall when the bank angle gets too steep. I guess I didn't realize that it would require a PhD in servo mixing to get this plane to fly well in tight turns. I'm certainly not a beginner when it comes to thermal flying. My main point is that my X1 tends to get progressively harder to handle when the thermal turns get tighter. There should be a FUNDAMENTAL adjustment for this. If there isn't, then I guess I'm on my own.

I have no problem trying to re-trim my plane next season, but I was hoping that there was a basic method for adjusting the trim that I could attempt for next season. I'm not looking to split hairs with regard to servo travel or snap flaps. The plane flies just fine, but seems to suffer from a lack of stability in tight turns, that's all. I can certainly screw around with +/- a few % snap flap mixes, but quite honestly I don't think that's going to do it. I need to try something more aggressive that will make a more significant difference in handling.
DrewV is online now Find More Posts by DrewV
Reply With Quote
Old Dec 07, 2014, 05:40 AM
dare to thermal
Mannheim, Germany
Joined May 2004
659 Posts
Do fly X or V-tail? Which wing joiner 3,5 or8 deg?
A video would be nice to get a definition of tight turns... more than 50 bank angle, turn radius 20ft?

Eg. these are not tight turns:
Dillon Graves on day 1 with his X2 3.8 Xplorer from Soaring USA (2 min 29 sec)


What i have noticed is the following: in tight turns CG location is more important than with a shallow bank angle. With a CG too far back, the nose rises during circling, CG too far forward, the nose dives in.
The other think im doing is to adjust diff, ail-rud mix, ail-flap mix in a way that for a specific speed roll axis stays straight and i have maximum roll rate.

/Bernd
Bernd Brunner is offline Find More Posts by Bernd Brunner
Reply With Quote
Old Dec 07, 2014, 08:15 AM
Registered User
United States, NY, Buffalo
Joined May 2013
1,348 Posts
Quote:
Originally Posted by Bernd Brunner View Post
Do fly X or V-tail? Which wing joiner 3,5 or8 deg?
A video would be nice to get a definition of tight turns... more than 50 bank angle, turn radius 20ft?

What i have noticed is the following: in tight turns CG location is more important than with a shallow bank angle. With a CG too far back, the nose rises during circling, CG too far forward, the nose dives in.
The other think im doing is to adjust diff, ail-rud mix, ail-flap mix in a way that for a specific speed roll axis stays straight and i have maximum roll rate.

/Bernd
All good questions. Mine is an X tail with stock joiners, I think 5 degree. When I speak of tight turns, I guess I mean something between 10-20 ft radius.

As I said, I'm around 110mm CG right now. I can try pushing it back to 115mm and see what happens.
DrewV is online now Find More Posts by DrewV
Reply With Quote
Old Dec 07, 2014, 11:04 AM
that's gonna hurt...
USA, CA, San Jose
Joined May 2005
1,179 Posts
Tuned many X1s, both mine and club members - I'm betting it's a differential problem.
Measured on the wing, take out almost all the differential, I leave just enough so I know I have some.

I chased the same problem for months on my 1st X1.

Bruce
blewis01 is offline Find More Posts by blewis01
Reply With Quote
Old Dec 07, 2014, 11:21 AM
Registered User
United States, NY, Buffalo
Joined May 2013
1,348 Posts
Quote:
Originally Posted by blewis01 View Post
Tuned many X1s, both mine and club members - I'm betting it's a differential problem.
Measured on the wing, take out almost all the differential, I leave just enough so I know I have some.

I chased the same problem for months on my 1st X1.

Bruce
Interesting. I have 2:1 differential right now. From what I understand after reading through this thread, that's pretty standard.

So for adverse yaw compensation you just have ail/rud mix? How much mix do you have there?
DrewV is online now Find More Posts by DrewV
Reply With Quote
Old Dec 08, 2014, 01:14 AM
that's gonna hurt...
USA, CA, San Jose
Joined May 2005
1,179 Posts
Drew - Have not measured actual throw for awhile - on my JR 9503 I show 50% ail / rud mix in thermal mode and 40% in cruise, not sure what that actually measures. Once the bank is established I use rudder stick to coordinate turns.

FYI - I tried the 8 degree joiners on the X1 and did not like them because the roll response felt sluggish. I do like those joiners on the X2 though, although only use them in super calm conditions.

Bruce
blewis01 is offline Find More Posts by blewis01
Reply With Quote
Old Dec 08, 2014, 11:48 AM
**coming to a town near you**
FlyingGorilla83's Avatar
United States, NM, Albuquerque
Joined Apr 2013
876 Posts
I used the 8 degree joiners this weekend at the F3J in December event in AZ. The X2 floated like it had helium in the wings. Everyone was coming down and the X2 3.8 was just flying in slow motion. about 1.5mm of camber and that baby just wont come down!!! I agree, a little sluggish in turns BUT, in light air all I had to do was lightly move the rudder and then do nothing. 2 seconds later the plane started a gradual and flat turn, perfect for calm conditions. The X2 with 8 deg joiners launched like a beast too, I was getting 100-150ft higher than the field at times, especially on downwind launches. I cant wait to see what the X2 launches like with the regular joiners!! Cheers!!
FlyingGorilla83 is offline Find More Posts by FlyingGorilla83
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion RADINA 2 by NAN models Pinci Hand Launch 38 Feb 11, 2009 01:58 AM
Question Speed 1.5 /Nan Models. Alex Mini 1.5 setup question Broncomech Slope 20 Jul 23, 2008 10:47 PM
Discussion Nan Models Shadow ( sorry for the mistake ) Chipwillis Thermal 56 Apr 19, 2007 05:44 PM