Props and high speed

[jolyboy]

Can someone please help explain the calculations and parameters that go into selecting a suitable prop and drive system for high speed flight? I'm in the process of designing a VTOL quadcopter-wing, the emphasis is on forward speed in aeroplane mode. It's going to be based on a delta wing, wingspan 1400mm, AUW ~2.7kg. I'm aiming to go around 200-250kmh if that is a plausible goal at all (?).

The prop system I will use for the first prototype is 4s, four 900kv motors with 8 x4.5 props (thats what I have lying around). The pitch speed on PropCalc gives me only 85kmh

I plan to upgrade after it is flyable, so are there any suggestions to aid achieving the goal? Thanks for any help

[jolyboy]

Never mind, I found the answer. RPM and high pitch are what I need. Not sure why I found it so challenging to get my head around lol.