CellTech

I am currently building a Super Sportster 60 from old kit plans. This is a scratch build project in which I downloaded the manual on the Great Planes web site. Wing is done and I am now on the fuselage construction. I plan on using a ASP 80 4 stroke. The manual states to keep the trust line the same as on the plans which is 0 degrees offset for four stroke mods. This is what bothers me since 4 strokers have a tendency to pull left do to the engine torque.

Now I also have the RSM plans for the 120 Super Sportster "nex projeet" and plans show 2 degrees offset and shortening the right front fuesleage 1/8 inch to compensate as well as mount the motor slightly off center keeping the center thrust line. So I guess my question is what is the consensus? leave it alone or add offset.

Thanks!

Mike

ChuckW

I'm almost done with my SS-60. I'm using an OS .75-AX 2-stroke. I kind of felt like it should have a little right thrust too but plenty of people who built the kit said it is fine without it so I left it alone.

I have the .90/1.20 plans too and all the materials here to do the build. I think I'm going to hold off on it though and build an Ultrasport and put together a Warbird ARF first.

chashint

The Super Sportster has a long tail moment so the affects of the engine torque are not to bad.
I followed the instructions for the firewall installation and the engine mounting and the plane flies very well.
Super Sportster 60, Magnum 91 four stroke, APC 14x6 prop.
Runs straight down the runway on takeoff with very little rudder required.

CellTech

I have decided to go with out any right thrust though I do prefer a couple of degrees. This design being as old as it is doesn't allow for any off set if the thrust line is kept down the center. Once the 3/8" nose doublers are installed their is zero space to offset the motor mounts to compensate for any thrust deviations in order to keep the thrust line centered. I downloaded the manual for the Super Sportster 60 which includes additional information for installing 4 strokes that was not included in the manual from decades ago. Though not a problem to retrofit to a stroker, the fuse would have to be widened at the front to accomodate any thrust changes due to engine offset from center. This is probably why the updated manual states not to add right thrust to the four strokes.