Thank you all for the replies, and its been a pleasure discovering all these models. The turbine legend really caught my eye, as did the RV8. Does anyone by chance know which of the Vans aircraft asisde from the RV8 are aerobatic rated?
The RV-3, 4, 5, 7, 8, and 14 are designed for aerobatics. The 9, 10, and 12 are not.
Part 91.9(a) is sort of the inverse, saying that you just comply with the operating limitations. So if the limitations prohibit aerobatic maneuvers, you can't do them. But that's not the same as requiring permission.
The experimental operating limitation language they use nowadays says only those aerobatic maneuvers performed during phase 1 testing may be done:
"If aerobatic maneuvers are intended to be performed during phase II, those maneuvers must be satisfactorily accomplished and recorded in the maintenance records. Aerobatic flight testing is not complete until sufficient flight experience has been gained to establish that the aircraft is satisfactorily controllable during the aerobatic maneuver tested. Upon completion of flight testing, the owner/operator must make the following or similar entry in the maintenance records:
"I certify that the following aerobatic maneuvers have been test flown, and that the aircraft is controllable throughout the maneuvers’ normal range of speeds. The flight-tested aerobatic maneuvers and speeds are _________ at _________, _________ at _________, __________ at _________, and __________ at _________."
During phase II operations, aerobatic maneuvers that were not documented per this limitation may not be performed. The owner may place the aircraft back into phase I for the sole purpose of adding additional aerobatic maneuvers to the aircraft authorized maneuvers."