OK, this may have been covered before but I need help. I have been flying RC since 1980 but I have never done twins. I now have 5 twin kits and am getting the first one together......a Hobbico Twinstar. I have elected to do the programming master/slave functions on the throttles as opposed to the Y-harness avenue. I have a Futaba 9CAP radio and am ready to start but the manual is really ambiguous as far as programming two throttle servos. They go into detail on several other mixes but not the throttle thing where you can disable the mix and run one engine and then enable the mix and run two and also the additional mix on the ATV of both servos. I'm really confused and can really use some help here. I am computer literate.........I make my living on a computer designing printed circuit boards and I have programed all of my other models but this is new water for me so I definitely will welcome help.

Thanks in advance,
Andy

Hi Oldtime,

Great to see another twin/multi flyer on RCU!

I am flying my twins/multis using a Futaba FF9 for two years by now. Unfortunately I don't have the manuals by hand now, but so far always use as few mixers as possible (In general: on Twins/Multis stay as simple with your electronics/onboard systems as possible!!!!)! The reason is the following: in flight in case of an engine failure you first dont get which one died - it's pure horror. So I have all my throttle servos on Y/double Y wires, going over 1 single channel. The problem is to do all the servo arms and push rods in the same length, but in case of an engine out you can stop /reduce to idle all the engines by moving one single stick or switch. According to my experience, you do not need the possibility to move your servos differently (given that you use the same servos/push rod size on all the engines).

Only on one plane I use a simple linear mixer, also with exactly the same servo arm/push rod lengths. I that case I don't know if there are any differences because the engines have a difference of 7500 on one side to 9000 on the other one (40 year old OS FS 60) - but it is no problem when flying!

For some more helpful info about how to get a long lasting twin/multi see also the following thread, especially have a close look to post N° 20: http://www.rcuniverse.com/forum/m_45..._1/key_/tm.htm

As soon as my exams are over I can have a close look to the manual and the FF9 and give you some further help on programming that radio!

regards
Chris

Running a mix has several advantages. The first is that you can adjust the travel on each motor very easily and that will allow you to get the motors running the same rpm at top end.

The other reason is when you get more twin time you can even very easily mix the throttles to the rudder and when you make rudder turns the engines will help you make the turn. It is nice for scale and real fun for aerobatic spins and snaps

The main thing is to fly happy

Multi, I believe the idea is that both throttles/channels will be controlled by the throttle stick, not two different controls.I do have one plane with separate throttles (just becuase I can...) and it does add to the pilots workload, as you suggest

Mixing the throttles will allow you to practice engine out under non-emergency conditions. You will need to know how to make a circuit and land with an engine out. Attempting to learn to fly on one engine out under emergency conditions is almost always a disaster.

Bill

OK........thanks for all the encouragement on mixing......that is what I want to do instead of a Y-harness, I'm looking for instruction on the best way to do it. The Top Flite manual for the DC3 suggests that the left engine be on channel 7 (slave) and the right engine on normal throttle channel 3. Now I need an experienced programmer to lay out how to accomplish this.

Thanks,
Andy

No one has mentioned this yet so... Here's an alternative ($$) in case programming help doesn't come thru
The Twinsync will do what you want in addition to keeping your engines in sync.
I have set the twinsync to use a three position switch on the transmitter. Position 1 controls the left engine fully from the throttle stick while the other engine idles. Position 3 does the same for the right engine. Position 2 controls both at the same time.

With both engines running moving to position 1 or 3 allows full control of one engine while the other goes to idle. No mixing is required in the transmitter.

You might go to RC Showcase and download the manual, and see what other options it has, like dropping the running engine to idle when one quits, then allowing full control of the running engine.

I don’t have a 9C but on a 8UAP slaving channel 7 to channel 3 is fairly straightforward. Sometimes after you start the question will become clear.

Bill

Hi!
As you have no experience flying twins I do suggest that you just use an Y-cable at first and after some years flying, convert to mixing two channels.
Flying twins aren't as easy as just flying a single engine airplane and it's important to keep everything simple.
Build it light and keep things simple and you will discover how nice a twin airplane will fly.

Regards!
Jan K

Andy,

Try the Futaba FAQ for the 9-C. They have exactly what you're looking for. Item 23 on airplane programming column. I used this setup on my C-47 and it works great.

http://www.futaba-rc.com/faq/faq-9c.html

Since nobody really answered your question, I will give you what I got.

OV-10 Bronco and 9CAP programmed throttle---

-Go to your program mix 1
-Mix -- ON
-MAS -- Thro
-SLV --Aux1
-Link -- OFF
-Trim -- On
-SW --B
-Posi -- Null

On the front screen with the rate %'s, I have the offset at 50% and the rates set to start and stop so that the servos don't bind.

Since the SW is set to B (dial), this is how you adjust one throttle to sync up with the other.

Obviously one throttle servo is on channel 3. The other is plugged into channel 6 or 7. I can't remember of the top of my head.

I hope this helps.