"Hmmmmmm......" Tomapowa, I do not understand the reason for the post.

Everyone that purchased the U Can Do had a copy of that sheet in the box. (except for early kits)

The warning refers to overpowering the airframe to achieve faster airspeed. In my case the Ys140 was installed for hover pullout power while learning to hover.

The Saito 100 may or may not have been the cause of the firewall separation. Many factors could be linked to the failure. Hard landing or two, Prop not balanced just right, Lack of glue, harmonics, to name a few. One of these or a combination of these (even worse) may have been a factor.

Any of us that overpower this plane gain faster airspeed should expect failures related to higher airspeeds. I KNOW that my plane will come apart if I do not use throttle management to limit airspeed.

On page 26 of the manual it refers to the OS120. The reasons listed for not running that combination are 1. Increased tail weight. 2. Would not sit still on the runway. 3. Poor throttle resolution in a hover.

The manual in the same paragraph states; "I do not recommend a 120 4 stroke or LARGER engine IF performance aerobatics are desired." Says nothing about keeping the firewall on the plane.

http://www.greatplanes.com/manuals/gpma1269-manual.pdf

Moving the RX battery to the tail kept me from adding extra weight and put the CG @ 4 7/8". Also the YS140 has offered excellent throttle resolution at any desired setting.

I think his post was meant to help others with this airframe.