Why aren't there more manned quad copter designs?

[voyager]

The vertical takeoff will sap a lot of energy. Is there a formula how to calculate how much energy for an aerial vehicle like the Airbus to ascend say the first 10 meters? At what vertical acceleration is there a point that one can safely say the aerial vehicle is airborne?

 

[voyager]

Hi guys,

Which companies, specialized in thrusters using fixed-pitch props for drones, do you happen to know that are able to engineer and build 4 to 6 ft diameter thrusters?

 

[quick_dry]

at that size you're talking to normal aero engineering place, or possibly the "giant" scale RC flyer people, though they'd tend to be using engines, not brushless motors.

KDE and T-Motor have large motors, but nothing that size (they probably could turn that size, but not with much authority.). At that size, for a full scale vehicle you might as well just go in a regular helicopter with a good flight controller. Also, that size is a lot of inertia to slow/speed up - keeping constant RPM but changing the prop angle would be better... and then you're back at a regular heli - except this one can't balance itself

 

[voyager]

How much kW does it take to lift 2000 lb from the ground vertically, generally speaking?
The approx. 2000 lb weighing Robinson R44 uses a massive 8.9 liter 245 hp (183 kW) / 507 lb-ft engine to get airborne. So, 11 lb per kW (or approx. 5 kg per kW).

 

[Dw911]

I seem to remember the us military experimented with various types of ariel vehicles designed to move a single military infantry man and his kit over say or to the battle field or wherever he needed to be, they tested all sorts, from quad coppers, jet packs, even something that looked like a trash can with rotating blades on the bottom - that whilst capable of flight, it would probably have killed more men than the enemy would have - in the end they pretty much concluded it was safer,easier, cheaper to just use helicopters.

So I imagine it's probably a case of been there done that, it cost a fortune, didn't work so we're not in a hurry to try it again at the moment, even if the technology might make it more feasible this time around