Date:	Mon, 7 Nov 1994 08:07:54 -1000
From:	tanaka_be@swam1.enet.dec.com (Bert Tanaka)
Message-Id: <9411071804.AA28940@mts-gw.pa.dec.com>
Organization: Division of Applied Sciences, Harvard University
Subject: Re: the Speed Limit

There have been a couple of inquiries on how the variable vents
in the Speed  Limit by Aerodrone Kites work.  

The kite has a panel of mesh in it which comprises the vent; one 
panel in each wing, located near the trailing edge, and close
to the spine.  Each vent has two flaps over it, that work a little
bit like a spring loaded set of saloon doors, and are located on
the back of the kite.  When sail pressure is low, the "doors" are
closed, and the vents are sealed.  As pressure in the sail increases,
the "doors" open backward, and release pressure through the vent.  The
amount the "doors" will swing open is directly related to the amount
of pressure in the sail: the more the sail pressure, the wider the doors 
open, and the greater the reduction in drive and pull on the lines.
The spine has a small standoff in the rear of the kite that bungi is
tied to, to provide leverage to work the spring tension in the doors.
The bungi, is not ordinary bungi - it is some sort of elastic material
that was selected for its superior memory and durability.

I liked a couple things about this system.  First of all, despite my 
explanation, it is very, very simple.  The real ingenuity was in its
conception.  It looks very realiable, and as near as I can tell, should
work without any need to adjust it.  Second of all, aside from the 
characteristics related directly to the variable vents (i.e., even speed),
the Speed Limit maneuvers the same whether the vents are open, or
closed.  If this kite had no vents at all, it would still be a great flying
kite.

Hope this helps,  Bert


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