bonanzadrv

My Feedback: (21)

I am setting up my topflite 310.

I have never flowen or set up a twin before, and am trying to use a mix for throttle. So I can get the right at the same RPM.

I tryed using the throttle curve but I could not get the trim to work on both engines.

I now have prinnted off the directions from Futabas website. But for some reason I cant get it to work right.

I was just wondering how other Futaba 9 cap people are doing it???

Thanks
Bill

JoeMamma

Hi Bill,

I have two twins set up on 9C's and one twin set up on a 10C Futaba, so I'll try to give you some help.

1. Plug the right engine throttle servo to the conventional channel #3.
2. Plug the left engine throttle servo to channel #8.
3. I'm using the center rotatable switch VR(B) for fine tuning channel #8.
4. Rotate this switch until the arrow is straight up. I painted a yellow dot on the knob as reminder that it should be centered.
5. Go to THR NEEDL and open it up.
6. You mentioned you changed the throttle curves. Go back and reset your throttle curves back to the factory positions at #1 0%,#2 25%,#3 50%,#4 75% and #5 100%.
7. While still in the THR NEEDL program, reset INH to ACT.
8. Find AUX-CH in the BASIC (ACRO) program and open it.
9. When in AUX-CH scan down to CH8.
10. While at CH8, rotate your selector until you get to Vr-B. All electrical programming has now been set.
11. When tuning both of your engines (perfectly I hope), be sure switch VR(B) is rotated to the top (neutral) position. The same holds true when setting up and adjusting all mechanical throttle linkage.
12. Using mechanical linkage, use a tach to attempt to get the rpm's on both engines as close as possible. Try not to use switch VR(B) at this time. What I'm attempting to do is to get you to tune and adjust both engines perfectly.
13. Make sure the transition from idle to full throttle is perfect.
14. After starting both engines, bring them up to full throttle. Most likely the rpm's will be different. This may change from day-to-day due to temperature and humidity changes. Now here's the neat part. Simply rotate switch VR(B) slowly to get a perfect rpm setting. You won't need a tach........you can hear it when those twins are in sync.

Switch VR(B) will only move the throttle servo on channel #8 to match the engine speed on channel #3.

Let me know how it works for you.

Joe M.

JoeMamma

I forgot to mention, switch VR(B) will not work at idle. The more you open up the throttle, the more servo arm movement you will get on channel #8 using VR(B). It seems to be some kind of linear setting used by Futaba.

I still haven't figured out how to get VR(B) to work at idle. Has anybody else figured out this one ?

Also, remember to rotate (reset) switch VR(B) back to the top (neutral) position after you're done flying. This will retain your mechanical servo arm positions.

Joe M.

bonanzadrv

My Feedback: (21)

JOE

So you use the knob to adjust the rpms when you are running the engines.

And then fly it. and before the next start you reset the knob?????

I right now have the servos on a Y connector.

When I run it to full power they are about 100 rpm off not bad.

When i idle it they are about 1500 rpms off!!!!! NOT GOOD

I want to be able to idle the one down a bit to match the rpms.

Will your setup do that?????

Thanks again
Bill

JoeMamma

Hi Bill,

The rotatable switch VR(B) is used only as a fine adjustment at or near wide open throttle. The switch should never be used to set up initial engine speeds, for tuning purposes or to adjust idle speeds.

You say you are getting an rpm variance of 1500 rpm at idle. Sounds like something may be wrong. I would first attempt to get the idle speeds the same.

1. Get rid of your "Y" harness and set up the left engine servo on channel #8 (see my previous post).
2. Be sure to use identical engines with identical carburators.
3. Be sure the servos on both engines are identical.
4. Be sure you are using identical servo arms.
5. Be sure you are using the same mounting hole on each servo arm.
5. Be sure you are using the same mounting hole on each carburator linkage arm.
6. Tune each engine independently.
7. After both engines have been independently tuned, adjust the mechanical linkage to get the closest engine rpm match.


Also see my note at http://www.rcuniverse.com/forum/m_7980812/tm.htm

Joe M.

bonanzadrv

My Feedback: (21)

OK Joe

I see what your doing now. Sounds like a great way to adjust and fine tune hi end.
I was just wondering if there is a way in the 9 cap to be able to adjust the servos independantly to get the carb barrels to match.

I have double checked my setup three times

same servos, engines, arms , holes in both arms.

For some reason I can match them at full power or at idle but not both. It is not an enigine prob the one just wont idle down (because the carb openings arnt the same)

I had tryed using the mixing on the futaba site but i got so screwed up I just went old school "Y" and linkage and got everything real close except idle.

Now that i am ready to fly I want it all to be perfect and this dumb radio should be helping me not hurting me!!!

Thanks for all your help

Bill