plasticjoe

My Feedback: (22)

I am building my first twin, and I am stumped on the throttle linkage. I want one servo to run linkage to both engines, but I am stumped, a dual bellcrank in the fuse maybe ? I tried a single cable splitting to a dual cable to them, but too much flex in the cable to get enough travel. The model I am building is an A-10 from Model Airlane News, Keith Sparks plans. Any help would be appreciated.

kram

My Feedback: (7)

I always run two servos. You can get some really small micro-servos if you're worried about weight/size. I've seen set-ups with dual bellcranks in the wings, but that gives four "slop points".......servo arm, bellcranks X 2 and throttle, which is too much total slop for me on twin throttles.

mt

bigbud

My Feedback: (16)

i am building the keith sparks a-10 also. i'm in the process of getting the wood list together. i looked at the throttle linkage to, probably will put two micro servos out on the stub wing looks like enough room. how far have you gotten in the building process . did you order the short kit or did you make everything. what size engines do you plan on using. sorry for all the questions i posted a question about the a-10 and didn't get many responses . i did get one guy who has been very helpful who built this plane.

let me no about any problem areas thanks

plasticjoe

My Feedback: (22)

I purchased the plans from Model Airplane News and cut all the parts myself. I am to the point of covering the fuse. If you got your plans from Model Airplane News I would like to point out that the wing plan has you building the wing wider than what the wing saddle shows on the fuse plan. I did not notice this until I was ready to cut the wing saddle. It was an easy fix due to the build of the wing. Anyway, the setup I have in it is as follows. B&D pneumatic retracts, moved the rudder servo to just forward of the CG to steer the nosewheel and operate the rudder. Mounted the battery, the pneumatic air tank, and the air switch and micro servo for it all under the canopy, made a canopy hatch to access these should they need adjusted. I also have placed 2 mini servos on the stub wings for the throttle linkages. Instead of building up the cover over the brass fuel line and pressure lines, I just left them exposed under the nacelle, and used a nifty epoxy sandable wood that you can get at Lowes to cover the area open between the fuse and the nacelle. As far as engines I am using 2 OS .40 LA's and am having a machine shop buddy of mine shorten the standoff of the mufflers to make fitting them in the nacelles easier. On the construction of the nose, you use triangle stock tapering torward the tip, I had to monkey with the formers and trim them some to get the uniform taper to the nose. I hollowed out the nose block so the retract air tank end would slide in there and rest into the servo compartment where the rudder servo was. I ordered the vacuuformed parts from Keith, the clear PETG nacelles and the canopy, cockpit parts ( instrument panel and seatback ) there was also a cover to hide the bellcrank on the tail that operates the rudders. All those parts are formed out of polystyrene ) Being very cold here in Ohio, I have yet to paint those, I am readying the Nacelles and devising a way to make them removable. I have had contact with a fellow locally here that has built this design, modified it to his specs some, and he has sent me pics of his, if you would like me to forward them to you, drop me an email at [email protected] and I'll send them over to you with his email to me and his address if you have questions for him also. I'll snap a few pics of the fuse and inside if I can tomorrow and post them. I also need to tackle the gatling gun, have not started that just yet. This is my first twin, so I am looking forward to giving it a whirl. Stay in touch I'd love to hear how yours goes also !

Roll On 60

I would not recommend you try for the bellcranks idea. Use two servos and a Y harness to the middle of the wing. Both Futaba and JR have a serve sync box that will get each servo the way you want them.

elmshoot

My Feedback: (6)

You can get some real small light weight servos for around $20 each it will be worth the $$ to avoid the headaches of the bell crank system.
Sparky

clscale-RCU

My Feedback: (7)

One servo per engine, all driven by the same channel. Put a simple straight pushrod or flex cable from the servo the engine. The bellcrank Idea sounds good, but the two servos is by far the best solution. treat each engine like it's own model airplane.

When I tune my engines this what I do:

1) run each engine by itself, get a good running idle, and high speed
2) then run both engines at the same time, idle and back and shut down both engines and watch to see which one quits first.
3) then I take the clevis on the engine that quit first, remove it from the engine and turn in a few turns (do not touch the needle valve)
4) run the engines agin to see what engine quits first, the goal is to have both engines quit at the same time, turn the clevis on one of the engines to speed up or slow down the engine to match the other engine. repeat this until you get it right.

You only have to do this once unless you remove the pushrods.

good luck,
Fred Cronenwett