Some questions about a VTOL UAV design

[harralk]

I'm working on a VTOL UAV with some upper classmen and I'm wondering if the design so far will be able to lift off the ground, and how much power (battery power that is) it'll need to hover at about 10 feet for 20 minutes. My concern is with ground effects and the amount of raw power needed to get the thing to lift off.

Weight: 15-20lbs
Height: 10 inches
Diameter: ~18 inches
Propulsion: 4x 127mm ducted fans, each rated at up to 12lbs static thrust (presumably at sea level)

Also, if it's not too much to ask, I'm curious about using thrust vectoring to steer/propel the UAV instead of the old-fashioned tilt-and-twist method

Thanks

[viscousflow]

Its almost impossible to predetermine in ground effects. This is where trial and error comes in to play. Just looking at the numbers i'd say you're ok but no way to tell until you test.
Also thrust vectoring a quadrotor is doable but now you're adding unnecessary weight for additional actuation mechanisms. How do you plan to implement it, and why would you want to vector it?

[harralk]

I had the same feeling about the extra weight of vectored thrust, why I first thought about removing it. Initially it was seen as a necessity because the terrain mapping sensors onboard need to be kept stable while they process visual data. After looking into it I found out the airframe only needs to pitch/roll a few tenths of a degree to maneuver around which won't interfere with the sensors.