I have a trainer plane and I am installing a O.S. 46 Engine. I have never done this befor and I need help. Is there anywhere on the net that explaines how to easily get the 1 degree right and down? I am just trying to figure it out and thought I would ask. Thanks! Wayne M.

Most trainers have the correct degree of right thrust and downthrust built into the firewall, so you just bolt the engine into place. Just make sure tht the centerline of the engine shaft is lined up with the thrustlines, and you should be o.k. What kind of trainer do you have? Is it a kit or an arf?

It is a Start 40 Evolution 2 (ARF)...VERY poor setup directions! Also, one more question. What are the steps of installing the fuel lines and suction line in the fuel tank? Thanks!

I'm curious - what is meant by right and down thrust? Does this mean that the engine is physically angled down and right? Or is it just the effects of the spinning prop? I know on full scale single props there is a roll tendancy due the engine torque, so does angling the engine in the model help with this?

I'm awaiting my LT-40 ARF, so Im sure I'll be having to deal with this soon as well.

Peter

OK, I was just looking at my trainer ARF plane and you are right, the fire wall is already 1* to the right and 1* to the left. It may not be that way with all planes but ithis one is! It is my understanding that the tweek to the right and down is to account for engine torque much like the rear tail prop on a helicopter. Don't take this as the law but I think that this is the reason.

I've got another question. I am building a Piper Cub PA-11 Special and I have never built a plane from scratch before and I was wondering if I should build the firewall like the ARF which is already on an angle or if I should build the firewall straight and mount the engine mount on the angle? Any Ideas? Thanks!

Down thrust is when you engine points slightly down. This is because you have a flat bottom wing which produces a lot of lift the faster the plane flys. To directly cancel this lift the engine is mounted pointing down so the more throttle you have the faster it goes, the more lift you have, and the more then engine pulls the nose down to cancel it all out.

Right thrust is when the engine is pointing to the right. This is usually done by putting washers under the left engine mount or by mounting the firewall so that it points right. The reason you want this is because the prop is slightly more efficient on the left side which causes the airplane to want to yaw left as you give it more throttle. Right thrust cancels that out.

To setup the right thrust on my trainer I put a laser pointer inbetween the fins on the head ( I figure they are inline with the crank) pointing backward and when the laser points to about 3/4" to the right (looking from front to back) of the rudder I call it good.

Hi there,

Can anyone tell me what is a Firewall in Engine?

Thanks

Mody

Thanks for the tip, Cheers!

right thrust is to counter engine torque thats why we can do torque rolls

Firewall is the surface that the engine mount is bolted to. In Full scales, it is what keeps the fire out of your lap if you have an engine fire. Hence the name Firewall.

Most fuel tanks have 2 lines, a vent, and a clunk. The clunk line is the one that has a rubber fuel line with a weight on the end, this one attaches to the carborator. The other angles up into a small bubble on the top of the tank, this is the vent line, and attaches to the pressure nipple on the muffler.

With your scratch build, you should put in 1 degree of right thrust, however, the downthrust is dependant on the design. If it is a flat bottom airfoil, then you want 1 degree of downthrust, if it's not, then you want it level. Also, if you build the firewall straight, then you can add washers behind the engine mount to get the proper thrust angles, so you can fine tune it based on how it flies.

SoonerAce,

Thanks for your reply.

Can anyone tell me normally on which mode radio's work, radios come with FM and PCM, I would like to know the difference between them and also wanna know can radio be switched on FM & on PCM and when they are required to be switched?

Thanks

Or use these:

http://www2.towerhobbies.com/cgi-bin...?&I=LXE952&P=7

Mode two is what most American flyers use. The throttle is on the left stick and the elevator is on the right. Mode one is just the opposite. It is called mode 1 because way back when (in the 60's) multichannel radios had the throttle on the left side and the elevator and elevator trim on the right side. When modern proportional radios came out flyers realized that real airplanes had the elevator and ailerons on the same stick and they moved the throttle to the left side and put both the aileron and elevator on the right stick. Since this happened after the original reed radios were used so became ModeII. Japan uses mode one almost exclusively. When I was stationed there I bought a new radio and had to learn to fly using mode I. Was a little exciting at first. Tended to resort to the mode I first used in an emergency. I can fly both now but almost all of my radios are mode!!

There are three ways to modulate radio signals in our radios. AM, FM, and PCM. AM is amplitude modulation, and FM is frequency modulation. Both use pulse width to send information. PCM is pulse code modulation and is still FM. The information is sent through a series of pulses rather than by changing the width of the pulses. That is a relatively simple explanation but will do. As far as which is better??? Take your pick. I am still using several old Futaba G series AM radios which work fine. I also have several FM Futaba's and Cirrus (Hobby Shacks' version of Futaba) and 5 PCM's. They all work well. Some guys swear by PCM but I have found they don't justify the price for everyday flying. PCM does have fail safe which is nice if you use old open ignition engines which produce a lot of radio noise.