Comments on: Backpack helicopter

By: Jake Simms

Jake Simms — Tue, 26 Oct 2010 08:18:40 +0000

Women and lawyers are great, aren’t they?

By: Roger Connor

Roger Connor — Fri, 22 Oct 2010 15:18:47 +0000

The Model 100 Hoppi-Copter (the one pictured) is on a display loan from the National Air and Space Museum to the Pima Air and Space Museum. The backpack machine never actually flew. Please email me about the picture featured.

Thanks,

Roger Connor
Vertical Flight Curator
National Air and Space Museum

By: Alex Kovnat

Alex Kovnat — Thu, 21 Oct 2010 13:42:54 +0000

DARPA (Defense Advanced Research Project Agency), whose basic mission is to think outside the box, isn’t working on a backpack helicopter but is working on something we might think is just as far out: A variant of the familiar High Mobility Multipurpose Wheeled Vehicle (HMMWV, “Hummer”) with a helicopter rotor on top so it can move 4 personnel over impassible land obstacles.

Said government agency did not exist until the 1957-1958 timeframe, when it was created by the Eisenhower administration in the wake of the Soviet Union orbiting Sputnik over our heads. One wonders if DARPA, had it existed in the 1955-56 timeframe, would have provided seed money and engineering talent for further development of the Hoppi-copter.

By: Ehud Gavron

Ehud Gavron — Tue, 19 Oct 2010 13:09:13 +0000

The dual ducted-fan concept was explored by SoloTrek, who had achieved more than 1 hr of flight time before getting DARPA as investors. Following this, in 2005, they “retired” their eXsokeleton Flying Vehicle (XFV). http://www.trekaero.com/Trek_VTOL_Vehicles.htm

Ducted fans are not helicopters. The distinction is subtle… but helicopters use the main rotor in its rotational path to create a disc which acts as a large circular airfoil. The top part of the disk has the low-pressure side, generating lift. A ducted-fan system has no airfoil (or “circular wing” if you prefer). It is merely a lifting-force device.

There are other differences. The ducted-fan devices being tested today and yesteryear (http://www.theregister.co.uk/2009/06/16/urban_aero_say_mule_test_imminent/) don’t use variable-pitch props (rotors) and are therefore unable to autorotate, nor to gain any advantage from forward motion. I would be remiss not to say that two small diameter fans generate less lift than a main rotor half their size (pi r squared).

Ehud
Tucson AZ

By: Paul Lisowski

Paul Lisowski — Mon, 18 Oct 2010 19:39:03 +0000

Another company is making a run at a personal helicopter (of sorts). The company calls it a Jetpack, although it uses a pair of reciprocating engines. See http://www.foxnews.com/story/0,2933,536622,00.html for a news article.