Re: Lifter - Autonomous with Aerodynamics? (fwd)

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Original poster: Steven Roys <sroys@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Mon, 22 May 2006 12:49:44 -0700
From: Jim Lux <jimlux@xxxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Lifter - Autonomous with Aerodynamics? (fwd)

At 06:45 AM 5/22/2006, you wrote:
>Original poster: Steven Roys <sroys@xxxxxxxxxx>
>
>
>
>---------- Forwarded message ----------
>Date: Fri, 19 May 2006 00:09:47 +0800
>From: Peter Terren <pterren@xxxxxxxxxxxx>
>To: High Voltage list <hvlist@xxxxxxxxxx>
>Subject: Re: Lifter - Autonomous with Aerodynamics?
>
>Hmmm... No one has, true but consider the case of lifter propulsion PLUS
>aerodynamics and the figures change. The Gossamer Albatros flew a 30kg plane
>with a 70kg person with 200W. If that 70kg person is a lifter supply instead
>then this is a large supply easily capable of 1kW at 100kV perhaps.


Developing lift in a very high L/D plane with forward motion is a very 
different matter than static lift.

if the GA had a L/D of 40:1 (typical of a high performance sailplane, just 
guessing that the  GA is in the same ballpark), then to support the 100kg 
(i.e. L=1000N), they only had to develop about 25N of thrust from the human.

This is the same reason that helicopters can fly at altitudes that are 
above the maximum hovering altitude. They can develop lift from the forward 
motion.

>This is only 1kg of thrust (at 1g/watt) but I am not sure how that compares
>with 200W power to an efficient prop.  Anyone care to contribute to these
>figures?
>http://en.wikipedia.org/wiki/Gossamer_Albatross
>Peter
>http://tesladownunder.com/Lifters.htm