I believe those fellas on the Harvard site are stretching it a little bit, that 'massive' engine is a 600 hp 9 cylinder radial engine used in trainers, a 'massive' engine would be something like an 18 cylinder radial engine producing 2,500 hp or even the 28 cylinder R4360 used in bombers and transports. I have a lot of time with the same engine they are calling 'massive' and 'massive' is far from what most in our industry would call an R1340.
The current turbine engines I fly now and have thousands of hours behind are turning 39,000 rpm and have a gear reduction transmission that turns the propller a maximum of 2,200 rpm so that it won't go faster than transonic for the reasons I stated above.
