L Edge
Master member
If you decide to fly a multi EDF plane and don't want to use a controllable rudder or designing a NYGAD without a vertical surface, you usually incorporate a mix that provides differential thrust. If you evaluate this issue from a vector analysis point, it ain't go-nah work on planes like the the A-10, Sr-71,DarkStar or B-2.
Say your flying the A-10, Sr-71, etc. and it keeps changing yaw in one direction when I add/subtract throttle. One of the problems it might be is because of not having 2 EDF's/prop motors producing the same thrust(I always use 1 large battery for multi engine). So your screwed.
My solution to you is remove differential thrust from the transmitter. By the way, my way does not use any mixes or extra channels. Just throttle and rudder to plug into. Now for the good news:
1) I can adjust both engines to start at one time so they are close to synch in the air by the trim switch.
2) At a fixed flying speed, I can listen to the engines to synch by adjusting the rudder trim. If you still have yaw, adjust the trim further.
3) If you evaluate a turn(especially the SR-71) it will give you a smooth turn, much better than a jerky differential mix in a transmitter. (Ask me how I know.)
Here it is.
A V-tail mixer.
How it works to program it. Lower left says elevator, so you plug it into RX throttle and upper left goes into rudder.
Right portion is where it is hooked to each of the ESC's. Recalibrate both.
Now start throttle a small amount. Both edf's should start.(trim later)
Now try small amount of throttle and now add small amount of say left rudder, you should see the right engine speed up and left slow down. If not, stop, exchange right hand side leads(don't you dare mess with left side) and do again so it should be correct. Hint-elevator on both goes the same direction to change Aileron-one side goes up and the other side goes down. Hey, that is differential thrust. All is left is runup motor small amount. If one starts before the other, trim it.(it should be close to sync). Now go almost full bore, to sync(listen to pulses), move other trim and the key is, when it is sync, you will hear the pulses.
Last, put plane in air, it should fly straight with even thrust, if not, leave throttle alone say at 90% , add/subtract trim(if you move throttle to 100%, added trim won't work) to make it fly straight. Then go back to tx, add some expo to your like.
Cost of V-tail mixer is about $12 and you should get a 200step function.
There are many problems with dual EDF planes, this eliminates one of them, especially the SR-71 because of the long nose in a turn.
Say your flying the A-10, Sr-71, etc. and it keeps changing yaw in one direction when I add/subtract throttle. One of the problems it might be is because of not having 2 EDF's/prop motors producing the same thrust(I always use 1 large battery for multi engine). So your screwed.
My solution to you is remove differential thrust from the transmitter. By the way, my way does not use any mixes or extra channels. Just throttle and rudder to plug into. Now for the good news:
1) I can adjust both engines to start at one time so they are close to synch in the air by the trim switch.
2) At a fixed flying speed, I can listen to the engines to synch by adjusting the rudder trim. If you still have yaw, adjust the trim further.
3) If you evaluate a turn(especially the SR-71) it will give you a smooth turn, much better than a jerky differential mix in a transmitter. (Ask me how I know.)
Here it is.
A V-tail mixer.
How it works to program it. Lower left says elevator, so you plug it into RX throttle and upper left goes into rudder.
Right portion is where it is hooked to each of the ESC's. Recalibrate both.
Now start throttle a small amount. Both edf's should start.(trim later)
Now try small amount of throttle and now add small amount of say left rudder, you should see the right engine speed up and left slow down. If not, stop, exchange right hand side leads(don't you dare mess with left side) and do again so it should be correct. Hint-elevator on both goes the same direction to change Aileron-one side goes up and the other side goes down. Hey, that is differential thrust. All is left is runup motor small amount. If one starts before the other, trim it.(it should be close to sync). Now go almost full bore, to sync(listen to pulses), move other trim and the key is, when it is sync, you will hear the pulses.
Last, put plane in air, it should fly straight with even thrust, if not, leave throttle alone say at 90% , add/subtract trim(if you move throttle to 100%, added trim won't work) to make it fly straight. Then go back to tx, add some expo to your like.
Cost of V-tail mixer is about $12 and you should get a 200step function.
There are many problems with dual EDF planes, this eliminates one of them, especially the SR-71 because of the long nose in a turn.
