programming a three engine project
 

I have started looking at my Futaba 8UAP for programming a three engine project. Later I will be looking at a JR 8103 for similar capabilities for a friend.

Here is what I would like to accomplish:
1. Top left corner switch shuts left engine down to 4,000 RPM and un-slaves engine. It’s the E or gear switch on my radio.
2. Top right corner switch shuts right engine back to 4,000 RPM and un-slaves engine. It’s the G switch on my radio.
3. Left pot (channel 6) changes the differential between center to left outboard. Left engine = channel 6.
4. Right pot (channel 7) changes the differential between center to right outboard. Right engine = channel 7
5. Throttle trim trims all three engines.
6. Sequence shutdown will be by trim pots.

Someone might already have experience and know the pitfalls. Any advice will be appreciated.

Bill S

RE: programming a three engine project
 

OH MY G--!!!
Uh........where is my 20 kid computer wize..........college????????????Dough!!!!!!
Could I suggest posting this one in the radio support for Futaba at http://www.rcuniverse.com/forum/Futa...mid_125/tt.htm
and let us all know the answer???
Twinman

RE: programming a three engine project
 

I got most of the programming prototyped but found two major issues. First I do not readily find a method to desensitize the pots or alternatively turn them off. Second channel 6 is distinctly different from channel 7. The original code logic is remarkably convoluted and the intent of the logic is not yet understood. I did present a simplified question in the Futaba forum earlier today.

Bill S

RE: programming a three engine project
 

BillS:

May I respectfully sugget that the programming you wish to accomplish will have you in a race with the men in white coats?

Haw.

Bill.

RE: programming a three engine project
 

Just curious as to why you want to complicate the engine controls? All my multi engine planes run the throttle of of one servo and with broken in and reliable engines just a little mechanical linkage tweeking gets them surprisingly close.

RE: programming a three engine project
 

Bill,

The primary objective has always been avoidance of men in white coats. A remarkable amount of success has been achieved to date.

The programming issue is going to be solved.

Bill S

RE: programming a three engine project
 

pkoury

I simply want to experiment with simulated engine out in non-emergency time.

Bill S

RE: programming a three engine project
 

Bill Baxter at Futaba pointed me to the following link to turn off the pots.
http://www.futaba-rc.com/faq/faq-8u-q52.html

I followed the instructions using PMix-7 only to get a bizarre throttle curve that reversed at mid throttle. PMix-6 also looks like it would produce a bizarre curve.

However I was successful using PMix-5 to desensitize the channel 7 potentiometer. At –95% settings the full range of travel of the pot produces a few degrees of servo travel approximately equal to moving the control arm one spline. Using channel 7 to trim the #3 throttle effects the servo over the entire range of travel. Incidentally PMix-2 was used to slave channel 7 to the stick on the transmitter and two mixes are required for each engine slaved.

I have not been successful yet in desensitizing the pot for channel 6.
Correction: Channel 6 also works but there is a 3 click dead spot at low throttle. If necessary the dead spot can be fixed in other ways.

Details can be posted if they are needed. White coats have again been avoided.

Bill S

RE: programming a three engine project
 

Bills
Welcome to twinsanity. You have now earned a place............and thanks for the information.
Twinman

RE: programming a three engine project
 

Twinman,

Your comments are appreciated. We should thank you for the abundance of valuable information and inspiration you continue to provide.

“The devil made me do it.” Or at least think about it. While exploring the bizarre throttle curves of PMix-6 and 7 your radio crossed my mind several times. With the flip of a switch it’s possible to activate the most out of sync throttle curve imaginable. The kind of out of sync condition that would make the most skilled expert pray that both of the damn things would simply quit.

Are your flying friends devious? Do you ever leave the transmitter unattended? Where is the key for the transmitter case?;)

In any event a lot of possibilities exist for creative control of the ‘not my airplane’.

Bill S