hotrod180 wrote:I believe LSA limits to 120 knots (138 mph) top speed in level flight.
This is kind right. From FAA FAR 1.1:
(2) A maximum airspeed in level flight with maximum continuous power (VH) of not more than 120 knots CAS under standard atmospheric conditions at sea level.
The question then is what is maximum continuous power and who defines it.
"Rated maximum continuous power, with respect to reciprocating, turbopropeller, and turboshaft engines, means the approved brake horsepower that is developed statically or in flight, in standard atmosphere at a specified altitude, within the engine operating limitations established under part 33, and approved for unrestricted periods of use."
Who defines Vh?
I don't have the citation at hand, but my recollection is the manufacturer defines that. In my Cessna T210, the take off power was somewhere around 300 hp but the maximum continuous power was 285. Carbon Cub uses this in their LSA so they hang a big engine on it and then say you can't operate at more than a certain percentage of power after a certain time.
As an upshot, yes we care limited to 120 kts Vh but we can do 140 kts indicated at altitude and we can hang a 200 hp engine on the plane as long as we (the manufacturer) establish Vh which meets 1.1.
At least, that's how I think it is.