Expert: Mark Janus - 11/9/2011

Question
I was curious... I was reading about VTOL aircraft in particular the LTV XC -142 and one design problem came up according to Wikipedia where the design produced an estimated 10 psi which would blow people around on the ground (when the craft is landing).

Is this not obvious in the sense that a heavier object will require more thrust ie more psi to keep itself hovering?

Or is this based on area where a helicopter has a larger diameter therefore the surface loading is less since the propellers on the 142 may be 1/2 to 1/3 of the size of a large helicopter.

Thank you for your time.

I am currently an engineering student
I'm fascinated with aviation
This is why I ask

Answer
I'm not sure of what is meant by 10psi when landing unless they mean stagnation pressure on the ground plane...  certainly the smaller diameter props will have to move less air faster (compared to a heli rotor) to accomplish the same result (i.e. hover or VTOL)...   

mj