I have been asked about the RCS radial fitting into the cowling. I checked the dimension sheet on their site and see that the 150 it is 10" in diameter and 8.5" long. Attached are some photos to help answer the question. The stick is 10" long and fits well into the cowling. The engine mounting box is long enough that it could be adjusted to accept the longer engine. The RCS engine weighs 9.48 pounds. The 3W engine weighs only 4.75 pounds and I needed 21 oz of nose weight to bring the CG to the correct location. This leaves 3.6 pounds of additional nose weight with the RCS engine. The plane will have no problem flying at this additional weight. You might need to move batteries back to the CG location and possibly some additional tail weight. Since I do not have a redial engine I do not know how the power compares to the 3W75. The cost of the engine is another issue.

Charlie