RE: Great Planes RV-4 .60
Please don't waste your money on 100 octane gas in a DLE. Their compression isn't high enough to exploit anything much above 89 octane. Don't put much faith in static thrust numbers, either. This RV-4 won't be judged by how well it pulls out of a hover. It's not that kind of plane. "Sport" planes spend their lives at higher average airspeeds that have different prop requirements than 3D. Many say that the optimum 3D prop for the DLE30 is a 19-8. For speed with a relatively clean airframe, a 16-12 to 16-14 works well. This RV is somewhere inbetween. IMO a 17-10 would be a good balance between speed and climb. This plane has LOTS of prop clearance so at least that's not an issue. The hot rod RV-4's at our field (there are at least 4) are in the 120-130+ mph range. At this point there haven't been any structural problems YET. I don't think you could push one much further with the stock tail surfaces, though. Early on a few people had problems with horizontal tails parting company with the rest of the airplane with predictable results. GP even replaced a few that were shown to have sub-standard wood in the tails. Were I to build another one, I would replace the stock horizontal tail with one made from a solid balsa sheet. It would be stronger and also heavier, which is needed with a larger engine anyway. I've never heard of a problem with the vertical fin or rudder, so they may be OK as is. Blasting around at three digit-speeds requires prudent handling. By that I mean SMOOTH. A stick-banger's relationship with this kind of hot rod will be a short one.