GURPS 3e: Making a duct-rotor helicopter

Anthony · 01-15-2022, 05:43 PM

A more realistic treatment of fans in Vehicles would allow you to specify fan area and fan power separately; the reason helicopters have high lift efficiency is just because they have extremely large fans (lift is actually proportional to the 1/3 power of area and 2/3 power of fan power). The SA-2 Samson has similar fan size to area to a V-22 Osprey, which is pretty underwhelming as a helicopter.

The main problem with ducted rotors for helicopters is the 'why' problem -- it's a bunch of weight that serves no purpose in normal flight. It's useful for microdrones because it reduces damage (to both vehicle and object struck) when colliding with environmental objects, but at the sizes and speeds of full scale aircraft it will just be slightly differently shaped wreckage.

01-15-2022, 05:43 PM	#8
Anthony Join Date: Feb 2005 Location: Berkeley, CA	Re: GURPS 3e: Making a duct-rotor helicopter A more realistic treatment of fans in Vehicles would allow you to specify fan area and fan power separately; the reason helicopters have high lift efficiency is just because they have extremely large fans (lift is actually proportional to the 1/3 power of area and 2/3 power of fan power). The SA-2 Samson has similar fan size to area to a V-22 Osprey, which is pretty underwhelming as a helicopter. The main problem with ducted rotors for helicopters is the 'why' problem -- it's a bunch of weight that serves no purpose in normal flight. It's useful for microdrones because it reduces damage (to both vehicle and object struck) when colliding with environmental objects, but at the sizes and speeds of full scale aircraft it will just be slightly differently shaped wreckage. __________________ My GURPS site and Blog.