I am mounting a Magnum 46 in a Phoenix extra. The manual shows by diagram 1 degree down thrust and 5 degrees right thrust. Does this indicate to point the nose of the engine UP 1 degree and left 5 degrees to achieve this? This is only my second ARF build -- the other was a Sig 4 star -- and I didn't pay any attention to any thrust. The plane flew fine,maybe I lucked out, but I don't want to take a chance with the extra.

Most (well, maybe many, but those I've built latery have) kits (arf's) have the engine thrust offset built in to the firewall. Check you kit/arf specs to see if it's already there. If that's the case, you only have to mount the engine and go from there.

DS.

In a high wing plane with a lifting airfoil, some down thrust is used to keep the plane from climbing a lot when the power is increased. On a low wing plane, down thrust could cause the model to lower the nose when power is increased, though to make this point clear, you would need a huge amount of down thrust. Now if you are asking about a plane with a symetrical airfoil and the thrust line and wing are fairly well lined up [like on a typical sport plane], no down or up thrust is needed. Some right thrust might be good as a fine tuning tool, but this can always be played with after you feel the plane out. Those black plastic engine mounts are easy to hand work any angle you want by filing away material on the back side where it mates to the firewall. Final thrust angles are easy to check if you bolt a long scrap of something straight in place of the prop and hang an angle finder to it after you have leveled up the plane / wing / stab, or whatever you are setting this angle in reference to. Setting the correct angle isn't brain surgery and the exact angles aren't that critical on a 60-70 mph model, it is done for convenience to favor a certain mode of flight, but it can hinder the way the plane behaves in other modes of flight.

Thanks for the info. What I really need to know is what direction to move the engine to acheive thr right and down thrust. If I am looking at a diagram of the plane from a top view with the engine at the top, do I point the front of the engine to the left to get right thrust? Looking at the plane from the side, do I point the engine up to get down thrust?

Oh, look at the angles like you were sitting in the pilots' seat.

OK, but which way to point the engine to get right and down thrust?

OK, if you are sitting in the pilots' seat and look off to the right, that would be the direction to cock the engine for right thrust. If you look down at your feet, that would also be the direction to point the engine for down thrust. The tricky part is to grind both angles into your engine mount or to position the firewall with both angles included. I would favor having the firewall set at zero-zero and work over a $4 engine mount to get the desired angles.

Down thrust means point the engine "DOWN", right thrust means to point the engine to the "RIGHT". It is best to follow the manufacturers recommendation and put in the proper thrust settings before that first flight.

"The manual shows by diagram 1 degree down thrust and 5 degrees right thrust. Does this indicate to point the nose of the engine UP 1 degree and left 5 degrees to achieve this?"

I don't understand how you could possibly come to this conclusion. You state that there is a clear cut diagram to follow. The engine points down and to the right as viewed from the cockpit.

Dyslexia? Not enough sleep?

NO, there is no clear cut diagram----just a drawing of a plane. If I knew the answer you think I would be posting??

Thanks for your answers AND patience, combatpigg!

YOUR initial post said there was a diagram. How was I to know you weren't telling the truth?

Garland, what type of plane is a Phoenix Extra? The reason I ask is because the only plane I've ever built that specified that much right thrust was a Goldberg Ultimate Bipe. The plane tracked beautifully and handled during takeoff real nice, too. I scratch built a twin engine bipe that had the engines mounted on the low wing. Those engines needed lots of down thrust or else the plane would have needed full down elevator to just fly level. It is interesting how even the most bizarre design layouts can be made to fly well by pointing the engine in the right direction.

Of course not all manuals are created equal. The engine mounting section gives the dimension for the engine distance to fit the cowl, but does not mention anything in text about thrust angles, only that small drawing. There's also no specs stating that the thrust angles are built into the firewall. I think I'll just mount it straight on the engine mount (which by the way came mounted on the firewall from the factory) then take some measurements to check!

combatpigg - this might be it:
http://www2.towerhobbies.com/cgi-bin...&P=SM&I=LXGPL7

That's the one

Thanks for the link, that is a beautiful plane. No way could that sucker end up at 3.5 pounds RTF? I would guess that it weighs closer to 5 pounds RTF? It is amazing to see all the features and details you get for that price.

99% of all arf have right thrust built in. if it has the engine mount already mounted place or engine in with the wings on and the prop take a tape measer at measure the distance from the left side of wing and the right side . the measure should be smaller on the right side