As some of you may know from another post of mine, I recently purchased an already built plane from a hobby shop that I'm hoping to learn to fly this coming Spring/Summer. It came with no radio. Studying the plane and trying to figure it out, I'm starting to come up with some very basic questions:

1. Why would you want right engine thrust and downward thrust? Does every plane require this? What determines what you might need?

2. Where do you put the receiver antenna? When I used to do boats, I'd just run it around inside the hull, but that boat was always in pretty short range. The plane I bought has a hole in the fuse for the switch, and it also has a tiny hole drilled right beside it? Could this have been for the antenna? If the antenna is supposed to exit the fuse, how do you anchor it on the plane?

3. Does expo on a radio simply dampen the controls? Will all quailty radios have it? I've been researching radios and it looks to me that a good choice might be one of the lower end computer radios.....I can't remember the model numbers...they ranged from $150-175.

This forum is great and I'm sure I'll have tons more questions. I know an expert that has promised to teach me to fly but in the meantime, these questions keep popping up> Thanks in advance to all who answer.

For thrust....yes, just about all planes need down and right thrust. Some as little as 2 degrees. Reason for this is engine torque.
If you had a plane with the thrust line perfectly straight, once you take off, the plane would most likely pull to the left, this is because of the torque of the engine. I'm sure someone else will chime in and have a better explanation than me.
Antenna routing. Mostly on glow aircraft, especially arf's, there is a tube that runs from where the servos are mounted and rx to the
back of the plane (inside the fuse). You would thread your antenna wire thru this tube. However, my U Can Do, I routed the antenna out thru the on/off switch hole and to the back. So, it depends upon which plane you have.
Expo on radios. Usually on mid to high end radios. My Hitec Flash 5 has it and so does my Futaba 9C. Expo is very useful in new planes where you set up your control throws and add expo in. It works by slowing down the response or movement of the control surface by proportion to the stick movement. Example may be....you move right aileron (right stick) 3/4 of full stick movement, and your control surface only moves about 40% instead of the 75%...but as soon as you go past the 3/4 of full stick, then the aileron moves much faster to its full amount. This is very helpful when you are getting used to a new plane. I have expo set on my U Can Do and my H9 Twist as the control surfaces on these planes are very large. Hopefully, DBCherry and others will chime in and add to what I've posted. Those guys helped me out tremendously! And I am still learning too!

Dave...

dsk,

Lucky gave you a very good basic description of all of your questions.

As far as mounting the antenna either inside or outside the fuselage that is more personal preference than anything else on glow/nitro powered planes. As far as mounting it outside the 2 most common ways I have done is out through the bottom and either taped with scotch tape to the underside of the fuselage or in the case of a tail dragger then using a rubber band is usually connected to the tail wheel mount

The other way is out the top of the fuselage I usually run it out just behind where the canopy (if the plane has one, most traineres don't) then push a "T" pin into the top or near the top of the vertical fin with a rubber band connected to it. Now tie the antenna to the other end of the rubber banding while strecting the antenna/rubber band to keep slight tension on the antenna to keep it straight.

The key is not to cross the antenna wire over itself at any point and to make sure it's full length is extended (all 39 inches of it)

The way most people connect the antenna to the rubber band is with either a button or part of a servo arm. Maybe Minnflyer or someone else has a diagram on how to do this. The button/servo arm also makes a great strain relief for the antenna on the inside of the fuselage right where the antenna exist. That way if the plane suffers a crash or is mishandled the antenna will survive well.

That's one of the few things I don't have a drawing of, simply because I never run my antennas outside the plane.

If the plane doesn't already have one, mount a piece of thin tubing inside the fuse. This can be anything from a piece of outer pushrod tube to a couple of drinking straws stuck together. Then run the antenna down the tube.

Thanks for the response...one question that wasn't answered....whats the purpose of downward thrust? And on the subject of right hand thrust, can you compensate for this by a bit of rudder trim? The reason I ask is this.......the fella that built this plane read the instructions, which were wrong, and put in LH thrust. I reworked the engine mount to correct this and I'd guess by eye that my RH thrust is pretty minimal. If I stare at it long enough, I'd guess 1 degree. Given that my flying experience is nil, I'd like to minimize any problems BEFORE I push the throttle forward. It was pretty easy to lay out the proper RH thrust, but it was a bit more tricky using my dremel to cut the hole. Hard to keep that blade going straight...and unfortunately once you cut the hole, you can't just hog it out more as it you lose the wood needed for the screw holes. thanks, Guys

Down thrust is typically neccessary on high wing cabin type or parasol airplanes. On these aircraft where the thrustline is located well below the center of mass of the airplane, thrust will tend to pitch the nose upward and every time the power is changed there will be substancial pitch change and down thrust tends to minimise this. Mid wing or low wing airplanes usually never need downthrust.

The purpose of the right thrust is a combination of factors with 'P' factor being the most important. This occurs strongest at high deck angles, low speed and high power settings, It always results in a yaw to the left around the vertical axis. This is because the right side of the propellor disc is producing more thrust under the condidtions mentioned earlier. These descending blades are at a higher angle of attack than the ascending blades. This condition is minimised not entirely eliminated by the use of right thrust. To answer your second question, Yes rudder is the proper corrective action to prevent this yawing. The use of aileron to correct will actually make things worse. However if you trim the rudder to correct this which only occurs at takeoll and climbout or high angles. Then for the rest of the flight you will be flying around in a right skid, not real purdy. This is the primary reason why right thrust is used on many airplanes.