tm303

My Feedback: (1)

I'm building a 4 Star 60 which will have an OS91 four stroke for its motor. My plans are to turn the engine on its side and cowl it. To get the look I'm going for I would need to raise the engine about 3/8 to 1/2 inch. Can any tell me if this will have any ill effect on the flying caricteristics of the plane. Some of the other modifications I plan on making are taking a bay off each side of the wing and adding one inch to the rudder.

ChuckW

It should work just fine. I did the same thing on a 4-Star .40 and it flew great.

Mr67Stang

I would try to maintain the engines stock centerline location to the firewall to maintain the designers thrust line. Turning it sidways should not be a problem once you remove the cowl cheek of course.

frenchie79

I put a fiberglass specialties cowl and mounted it sideways-Cools well and fly's great. You should need to balance the plane side to side
http://www.rcuniverse.com/forum/m_6748796/tm.htm
Check my build page out sounds like your after alot of what i did. Carefull on how you mount your engine-proper thrust angles and all.

buzzard bait

I mounted my OS 70 FS on it's side on my 4*60, and partically cowled it in using balsa block, and love it that way. I also moved the thrust line up a tad. Changing the thrust line, within reason, does not do much. At most, in this case, it could give a slight down thrust effect that you probably would never detect, and would not be a bad thing in any case. When you get to pylon mounted engines on sea planes, then yes, you will notice the effect.

Jim

ChuckW

Here's the one I did on the .40 size. I just rotated the engine 90 degrees but I think the cowl shape would have looked better with the engine raised a little. A 1/4" or so won't have any huge negative effect I wouldn't think. As long as the firewall is installed according the plans the thrust angles will be correct.

SeamusG

My 7.5 lb 4*60 has a Saito 91 installed.

I use a Zinger 13x6/10 multiple pitch prop. I have found that this particular prop provides a significant (aka very noticeable) kick in the pants during the transition from idle to mid throttle - much more than a constant pitch prop like a 13x6.

This performance profile caused a bit of a problem during takeoff where the pilot (me) added throttle somewhat aggressively. I like long run outs, straight down the center of the runway with a nice easy climb out. That's just my preference - irrespective of wind conditions. With this prop and the mount mounted flush to the firewall, immediate left hand turns on throttle application were common place. Oops. A bit of unwanted left hand torque.

Sooo I added 4 washers to the left side motor mount bolts (2 each upper and lower) giving the plane a couple of degrees of right thrust. After the addition of the washers long straight takeoffs are easily achievable even with 10-15 mph quartering wind.

BTW my next (3rd) 4*60 will follow along with some of your mods - built up cowl, sheeted turtle deck, tank hatch, upgrade of tail feather surface area, shorter wings - oops, just thinking out loud - sorry ....