Twin Engine Conversion
12-10-2003, 11:34 AM
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Twin Engine Conversion
Hello Guys,
I'm new to the forums. I've got a student building a Great Planes 40 Trainer. He has two identical OS .40 engines and would like to take his single engine kit and make it over into a twin.
Input please!!!!
Lobo in West Virginia
I'm new to the forums. I've got a student building a Great Planes 40 Trainer. He has two identical OS .40 engines and would like to take his single engine kit and make it over into a twin.
Input please!!!!
Lobo in West Virginia
12-10-2003, 01:35 PM
#2
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RE: Twin Engine Conversion
Wing will have to be secured better than with rubber bands!
Fueling will be a bit of a problem..
And I bet a bit of engineering to get thrust angles and offsets set.
Honest opinion.. not worth it. buy a twin kit..
The first task is to get teh wing secured properly to the fuse. Chances are, it'll have to be bolted in place. So, adding teh proper structure will be a must. And then teh wing will need reinforcement. that is, the center section will need to be beefed up to hande teh extra weight and loads. Also, pods / nacelles will have to be built in to accept the two engines. These will have to be placed far enough out to clear teh prop arc. As welll as planing for throttle servos (go with minis) and fueling. You can probably get away with two 6oz tanks built into the pods. Or a larger tank in the fuse with a pump. The engines will probably not just point straight ahead, but will have both down, and right thrust lines. What these are, I counldn't tell you!
Balancing is next. two engines are havier than one. But having two so close to the balance point will probably mean quite a bit of weight added to the noze to balance.. You can probalbly place the servos, Rx and battery in teh noze, to help balance..
When you say student and trainer, I'll assume a newbie flyer. This will probably be more trouble than it's worth when flying / learning. Twins with one engine out, DO NOT fly the same!! the plane will either fly sideways or corkscrew itself into the ground. A larger rudder may be required.
just some gut feelings..
Fueling will be a bit of a problem..
And I bet a bit of engineering to get thrust angles and offsets set.
Honest opinion.. not worth it. buy a twin kit..
The first task is to get teh wing secured properly to the fuse. Chances are, it'll have to be bolted in place. So, adding teh proper structure will be a must. And then teh wing will need reinforcement. that is, the center section will need to be beefed up to hande teh extra weight and loads. Also, pods / nacelles will have to be built in to accept the two engines. These will have to be placed far enough out to clear teh prop arc. As welll as planing for throttle servos (go with minis) and fueling. You can probably get away with two 6oz tanks built into the pods. Or a larger tank in the fuse with a pump. The engines will probably not just point straight ahead, but will have both down, and right thrust lines. What these are, I counldn't tell you!
Balancing is next. two engines are havier than one. But having two so close to the balance point will probably mean quite a bit of weight added to the noze to balance.. You can probalbly place the servos, Rx and battery in teh noze, to help balance..
When you say student and trainer, I'll assume a newbie flyer. This will probably be more trouble than it's worth when flying / learning. Twins with one engine out, DO NOT fly the same!! the plane will either fly sideways or corkscrew itself into the ground. A larger rudder may be required.
just some gut feelings..
12-10-2003, 03:57 PM
#3
Senior Member
RE: Twin Engine Conversion
Two .40s, no!
Two .25s, yes.
Place the motor nacelles just a bit more than a prop -radius- from the nearest contact point on the fuselage.
Seperate tanks.
A single servo with bellcranks can run the throttles. Or use two micro servos, one in each nacelle.
Nacelles can be simple Lite-ply boxes.
Open at the rear so you can see the fuel in each..
Use a remote glow plug extension for each motor, placed on top of the nacelle. No reaching around underneath!
Two .25s, yes.
Place the motor nacelles just a bit more than a prop -radius- from the nearest contact point on the fuselage.
Seperate tanks.
A single servo with bellcranks can run the throttles. Or use two micro servos, one in each nacelle.
Nacelles can be simple Lite-ply boxes.
Open at the rear so you can see the fuel in each..
Use a remote glow plug extension for each motor, placed on top of the nacelle. No reaching around underneath!
