Useful thermal mixes

[emersunn]

Which would be helpful for thermaling & competition landings?

Rudder > Aileron mix
Aileron > Rudder mix
Flap > Elevator mix
Throttle stick = Spoilers
Throttle stick = Flaps (and flap switch = spoilers?)

I am a little confused on the R>A and A>R mixes. Do you have the rudder respond to the ailerons in the same direction to make a coordinated turn or do you have the rudder go the opposite direction to prevent adverse yaw?

When I thermal the Colibri, I often "cross stick" - right rudder, left aileron - to keep the bank angle to a minimum and keep the wings horizontal (to catch more updraft). How would I program this mix in? Should I?

What I really want is to thermal slowly with just a little rudder input and minimal aileron input.

What's your radio setup?

[Ollie]

There are three ways to overcome adverse yaw. You can employ aileron differential to partially but, not completely, compensate for yaw in a coordinated turn. You can mix aileron to rudder so the rudder aids the turn to partially compensate for yaw in a coordinated turn. Both differential and rudder mix together will not automatically ensure a coordinated turn for all angles of bank. Some manual rudder input will still be required to make the coordinated turn perfect for some angles of bank.

The more dihedral you have, the steeper the bank angle before you have to use opposite aileron to prevent the circle from getting smaller. Even two channel rudder-elevator planes with lots of dihedral or polyhedral need opposite rudder in a very, very steeply banked turn.

If you can set the flaps up for more than about 60 or 70 degrees of maximum deflection and mix in the right amount of down elevator compensation, then spoilers become completely redundant and should be disconnected and taped shut, in my opinion. Fully deflected flaps will provide all the drag you will ever want or need. Flaps increase the usable speed range by lowering the stalling speed. Spoilers increase the stalling speed and provide no advantage if the flaps already have the need for increased drag covered. Put the flaps on the throttle channel and forget the spoilers.

The mixing ratio for flaps to down elevator has to be determined by flight testing at a safe altitude before attempting to use flaps in the landing pattern. Get an experienced club member, who is familiar with your model of radio and full house glider set up, to check your plane and its radio set up before you begin flight testing and adjusting.

The way to thermal slowly with little or no aileron input is to fly a plane with enough dihedral or polyhedral and a very low wing loading. The lower the wing loading the lower the angle of bank for a given size circle. You can also slow down in thermal turns by drooping the trailing edge of the whole wing about 3 to 5 degrees. This increases the airfoil camber and the maximum coefficient of lift without increasing drag a lot so that the stalling speed is reduced a little.

Setting up a six channel sailplane is a complicated task that needs to be approched slowly and methodically the first few times. Keep in mind that one switch that controls mixing and is out of position will likely result in loss of control and maybe a crash. If your radio permits, disable all mixing switches that aren't required to be used while flying.

[emersunn]

Thanks for all the tips. I forgot to mention this is a V-Tail/Aileron ship, so Spoilers and Flaps are really Spoilerons and Flaperons.

I really just have to practice the left thumb a little more. I was hoping for some cheats ;)

[Ollie]

Crow, ailerons up and spoilers down, just complicates things a bit more.

[ICTHRMLS]

Originally posted by emersunn
- to keep the bank angle to a minimum and keep the wings horizontal (to catch more updraft). Many thermals will not permit this type of circling due to their relatively small diameter. For these ya gotta yank & bank and the mixing I find the most helpful is trailing edge camber to up elevator. This will allow you stand on the wing tip, circle tightly and constantly stay in the thermal. It's tough to lose altitude on one side of your turn and gain on the other - you never get any higher.

Full up elevator will result in 1/4" - 1/2" trailing edge deflection and I put it on a switchable function.... not for launching or landing. Very little adverse yaw when standing on a wing tip.:D

Just an idea...................

[daking]

I dont know if this will help but here goes......

I fly a Philip electric 60 inch sail plane. It's a little on the heavy side for the size. It flys fine and float's pretty good till i get in a thermal, then it just stall's. I dialed in about 30% flaperon with elevator. That helped a ton. Still took a pretty big thermal to get it too climb. I set up a slider on my radio so i could dial in some flaps. Now when i hit a thermal i just drop the ailron's about 3 to 4 mil and BOOM, she goes up. Still cant work the small thermal but its a lot better then it was.

D