mooseflier

Hi, I'm building an OLD telemaster 40 that I bought off craigslist. It's certainly the oddest kit I've ever built, but that's another story. Iwan to make it less trainer-ish, and I found a good thread about that here: http://www.rcuniverse.com/forum/m_65...tm.htm#6748657

But there are a few chagnes that I'm making and I'd like to make sure it all sounds ok. Mainly I'm removing all of the dihedral from the wing and I'm not putting in flaps. If there's any issue with this I'd like to know about it beforehand. The other thread suggests also making the wing incidence 0 degrees. I guess the question is, if I have no dihedral, do I need to worry about the wing or stab incidence or the thrust offset for the engine in any way?

Thanks for any advice!

mooseflier

I could really use some help at this point. I don't want to build much else until i know how I should proceed. Two things I really need to figure out:

1. The plans call for a slight downward thrust for the engine. If Irotate the engine 90 degrees (muffler down), do Istill use the identical downward thrust, or does it change?

2. With a flat dihedral, what sort of incidence do I use for the wing/stab?

If anyone could help me out I would greatly appreciate it. Thanks!

soarrich

My Feedback: (98)

The the down thrust stays the same.

Dihedral does NOT effect incidence.

mooseflier

Thanks a ton sourrich! Very much appreciated!

eagledancer

you might want to keep the flaps, this plane floats forever with out them unless you have a very LONG runway

Zor

Most any plane will float if the approach speed is too high.

Controlling the approach speed and initiating the flare out a bit higher and at a slow rate results in very little float.

Zor

mooseflier

Thanks for the help and comments. Looks like I'll go with 0 incidence on both the stab and wing. I found another thread about this and that's what they went with. I still don't get the thrust, or why it has to be pointed down. Another guy mentioned that he made his with 0 down thrust and a tiny bit of right thrust. But I'll prob just stick to what's on the plans since I don't understand it. Just rotated 90 degrees so the muffler is down.

soarrich

My Feedback: (98)

There's several reasons to have down thrust. On a Telemaster the engine is below the wing, the wing is 95% of the drag. When you give it more power the thrust is below the wing which will try to pull the fuse forward, but the drag will try to hold it back, this will make the fuse rotate upwards. The down thrust tries to pull the fuse nose down. If the down thrust can counter the drag the plane will go forward without rotating up. On some seaplanes with the engine over the wing, or a sailplane with a power pod, they put up thrust in the motor because the motor is over the drag and without up thrust giving more power will make the nose go down.

0* incidence is good if you are measuring the bottom of the flat airfoil in relation to the flat stab. It actually gives you some positive incidence on the main wing, here's why. If you look at the drawing of the airfoil you'll notice that the front of the wing is rounded, it does not come to a sharp point at the leading edge. This round leading edge of the airfoil is where the incidence should be measured from, but when guys see a flat bottom airfoil they measure from the flat bottom. If you draw a line through the center of the radius at the front to the trailing edge you'll see you have 1*~2* positive incidence, which is perfect for you plane.