The laws of physics are the same
Steve Sampson said:
The RV4 VNE is 210 mph. The Rockets, forget the Evo for this conversation since it has a different wing, have considerably higher limits stated. The F1 claims a top speed of 250 mph and presumably the VNE is higher. The Harmon ii is I think 275.
My question is this. Since they are all sharing the RV4 parts, what aspect of the -4 structure is limiting it to 210?
Just curiosity. 200mph is fast enough for me!
One is conservativily engineered by analysis and flight test with built in safety margins. The other is eyeballed engineered and flight test shows it is also OK, but it uses up the conservatism built into the airframe, operating with less structural and aerodynamic margins?
The good news is there are lots of Rocket's being "test flown" every day and none have broke in-flight yet. (There was
Rocket II accident where in-flight break-up is suspected (not all parts in the same place(?); circumstance unknown but very turbulent flight conditions existed at the time.) So to answer you question the Rocket II has been proven in operation.
The original Harmon Rocket II (based on a RV-4 kit) clips the wing which helps wing bending to compensate for higher gross weight and speed. The tail I think was a stock RV-4 tail. However the Team Rocket F-1 does use a tail that resembles the later RV-7/8 tails now. The gage of metal may be increased, but I don't know.
Thickness of skin (structural flexibility) has only a little to do with flutter. Google Aeroelasticity or airplane flutter. (
Aeroelasticity) There is two or three ways to test for flutter: Flight test in the plane, Wind tunnel with scale models and analytically with
computer models. Here is some sobering Flutter info:
http://www.geocities.com/mgd3/flying/flutter
The question is does the flutter go divergent or is it non-divergent. There have been many RV's (one case documented in the RVator) where the pilot felt the "buzz" of flutter. Always keep in mind, go on TAS not indicated, so the higher you go the lower indicated Vne is. Any RV can exceed 250 mph TAS in a high altitude descent regardless of engine HP.
The laws of physics, aerodynamics and structural strength equally apply to RV's and Rockets. Whether the tail feathers are attached to a 200 mph RV-4 or 250 mph Rocket II, it is still subject to elevator, rudder and aileron flutter just the same. The result of flutter is also the same, from a buzz to total airframe failure.
The good news is Van has done a great job and there is some margin there. How much? Don't know, but apparently 250 mph is still OK. Dave Anders with his super fast RV-4 has been over 250 mph.
Would I fly a Rocket? Heck YEA! I would just watch the speed and flight conditions, slowing in turbulance and keeping Vne very much in mind.