Prop diameter is also a factor of max engine rpm, in that to avoid noise and performance issues, the prop tips must not go sonic, it was a "suggestion" on the PA39 Twin Commanche that as soon as possible after take off to reduce the RPM to 2500 in order to reduce the noise footprint, as 2700 RPM made for a significant noise footprint increase, as we discovered many years ago when night flying training at Lydd
. By 23:30, with my Twin and 2 Cessna 150's in the circuit, the phones were hopping in the tower. The vast majority, when asked if they took overseas holidays got off the phone very fast, and those that didn't had the facts of pilot training explained to them very simply, along the lines of "they wouldn't be doing it if it wasn't a requirement of being able to fly at night". It was a long night, we did something like 15 landings, most of them full stops, as touch and go landings were not recommended with the twin, and there had to be a specific number of full stop landings to get the rating..
The much larger engines on long haul piston aircraft operated at significantly lower revs, or were geared to reduce the prop RPM, which tended to make this an issue for the smaller aircraft. which were normally direct drive.
Ground clearance was also an issue, not only because of avoiding damage from actual contact, but also to avoid damage on unmade runways from small stones and the like picked up by the prop wash.