You want to set the C.G. to OCCUR at 100mm from the front of the leading edge of the TOP wing, when the plane is balanced upright at this point.

I fly the Ultimate 40S with a Tower Hobbies .46 ( a real stump puller ) which is more powerful than the OS .72 four stroker.

I've seen others fly the plane with everything from a GMS .32 2 stroke ( there is a review here on this at RCU ) up through an OS AX .55 2 stroke.

The .72 will fit, but it is about the largest four stroker you can get on the plane, not because of weight, but rather due to the cowling.



As far as the strut tabs go.

Just build your plane carefully.

The strut tabs are fairly strong, and if the strut comes loose, this is more of a builder's problem.

I've cartwheeled this plane nose-wingtip-tail-wingtip-nose-etc. accross an airfield with no visible damage.

I flew the plane immediately afterwards and for two weeks after that before I noticed that I had cracked one of the strut supports.

In spite of that I flew and landed the plane w/o incident. That is how durable the "box" shape of the wings are!

It is ONE TOUGH PLANE!

I epoxied a bit of triangle stock against the repaired tab, and painted this white.


After close to 300 flights I was waiting for this plane to crash so I could replace it with one of the two "backup" Ultimates I had purchased from NitroPlanes. ( I liked the plane THAT much! )

I finally cracked it up several weeks ago. While easily repairable, I decided it was time to "redo".