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This was fun to read:

This follows an article on the same subject in Aviation Week by Steve Trimble (for those who subscribe).

There are some great quotes in the VTOL article:

Quote (Col. Greg Fortier, Army Program Executive Officer for Aviation)

There's no version of the world... where the speed at range, endurance at range and payload all exist in a 14,000-lb helicopter

Quote (Mike Hirschberg, Executive Director, The Vertical Flight Society)

...aircraft with infinite performance at zero cost are built of “unobtainium.”

On further consideration, however, I'm not sure I fully agree. I looked up the Westland Lynx and find that it's pretty close to the performance targets cited in the article. No idea what operational targets are in the Army specification (and unlikely to find out!).

FARA spec
First flight: 2023
Maximum speed: 180 knot
Engine: one 3,000-shp GE T901 Improved Turbine Engine Program (ITEP)
Rotor: 40 ft diameter
Max gross weight: 14,000 lb

Westland Lynx
First flight: 1977
Maximum speed: 175 knot (with a 216 knots FAI record)
Engines: 2, combined power 2,700-shp
Rotor: 42 ft diameter
Max gross weight: 11,750 lb

So I don't yet see the physics problem. The Lynx is a bit light for the FARA spec, but not much. I can't see from the information provided how the Lynx and FARA compare in both payload and cabin seating, which are usually more important to the mission. Given the dual rotors of the FARA spec, there's a lot more structural weight expected there. So the Lynx may be closer to the useful payload than you'd think at first glance. For sure, the Lynx doesn't look anything like the counter-rotating rotor proposal that Sikorsky is showing. Maybe this colonel just objects to the ugliness.
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Is the physics problem hidden in their last bullet?, "mission"?


"Bell announced it had added a Pratt & Whitney PW207D1 turboshaft rated at 610 shp (450 kW) to its Invictus design as a supplemental power unit (SPU)"

So now they've got a twin engined design with twice the logistics trail of a normal twin engine.


Greg Locock

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