Help needed on First Engine Startup
 

I've recently purchased a Irvine Tutor 40 with a Thunder Tiger GP 42 engine. Planes built but i have the following question.

1 - As standard the engine carburetter had a tube inlet and i was supplied a needle valve as an extra. However if i unscrew the exisiting part the needle valve doesnt fit or screw in to the carb.
I tried to start the engine but nothing happend.

I've noticed if i turn the engine by hand it rotates but does get fairly stiff at a point. Once i've applied more presure it turns. How stiff should the piston be when moving the prop by hand.

2 - when i increse the throlle the rudder also turns (even though they are seperate servo's

3 - Is the need valve even needed?

many many thanks

gareth

Help needed on First Engine Startup
 

Let's see,

the needle valve is to ajsut how much fuel enteres the carburettor. Screwing it in make it lean, screwing it out makes it rich (first run engines should be on the 'rich side'). If it's too rich, or too lean, the engine won't run, at least not for very long. This should be a part of teh engine (already installed) and you'l probably need to open it up about 2 turns, maybe 2.5 turns. the oppicite side is the throttle arm, wich open or closes the carburettor.

Having popped onto the thunder tiger website, it looks as though the needle mght be an extra, in case you break it or something, I would re-read teh liturature that came with the engine..

Unless someone else has an opinion?!?!?

What is your method for startign the engine? I'm sure the product liturature should say something..



It's a 2 stroke engine.

As you turn the prop the piston goes up and down. As teh piston goes up, you'll be compressing the volume of air in the cylinder. Like a deisel engine, you're gonna get quite a bit of compression, that will make it hard to turn. And it'll pop over one you reach 'top dead center' [TDC] when the compressed air can finally expand to it's original volume and pressure. If you remove teh muffler, you should see the piston go up and down through the exhaust ports. Alternatevly, if you remove teh glow plug, you'll seee the same thing, and you also notice that it's really easy to turn!!

Sounds like you have a setting on your radio for a helicopter mixing setting. assuming your rudder 'deflects' to one side the more you increase teh throttle. You'll need to make sure it's set right - for planes. Your radio might have a 'mix control' knob. turn it to 0. Or you might have a setting in which they are coupled - throttle and rudder. And make sure the servos are plugged into the right sockets.

Or, you're wiggling the stick as you move teh throttle up and down!!

When a helicopter's throttle is increase, the main rotor spins faster, inducing more 'axial' spin. The tail rotor will compensate for this by increasing the pitch (bite) the tail rotor has, to counter the additional spin forces induced by the faster spinning main rotor.


Hope that helps.

If you could detail a bit more your problems, we shoudl be able to help you out..

Help needed on First Engine Startup
 

Your description is a little hard to follow, but I’m sitting here looking at my TT gp42 and I’ll try to help. First, what you describe as a “tube inlet” is in fact what the needle valve screws into, and should not be removed. There is a spring clip on the tube that will not allow the needle valve to screw into the tube unless you hold the end of the spring out a little until the needle valve has started. As you can see, the spring clip bears against the serrated edge of the valve to keep it from moving easily. After the needle valve is started into the hole, carefully screw it in until you feel it bottom out. Back it out two and one half turns which should be a good starting position. Now check the air bleed adjustment. There is a small screw on the same side of the carburetor as the needle valve. There is also a small hole (about 1/16 diameter) on the front of the carburetor that is the bleed hole. Look in the hole and adjust the screw until the end of the screw covers about one half of the hole. This will be a good setting to start with. With these settings, the engine should start and run a little rich.

Since you got the needle valve supplied separate from the engine, there is always the possibility that it is not the correct one. The TT gp42 needle valve is about ¼ inch in diameter overall. It has a sharp pointed end with very fine threads then a larger diameter shoulder with an “O” ring in a grove. There are then two serrated shoulders one to contact the spring clip to prevent the setting changing due to vibration, and the other to turn when making adjustments. This last shoulder has a hole into which an extension may be fitted and a setscrew to retain it. If the needle valve doesn’t look like this, it is the wrong part.

If you have never operated a small glow type aircraft engine before, I strongly suggest that you get some help from an experienced person before proceeding. If you must go it alone, e-mail me and I will send you a copy of the TT gp42 instructions and some pictures of the proper setup.