Archive of the Yahoo! Groups mailing list for the Bug hand-launch glider 2002-2018

From: Joshua Finn <joshuawfinn@...>
Date: Tuesday, June 30, 2015 7:31 AM
Subject: Re: [BugHLG] Launching
Truth of the matter is that if you can stretch the silicone twice as far as the usual stuff and still get the same force, the model will go significantly higher. Launch energy is directly proportional to spring constant, but is proportional to the square of the stretch distance. I fly free flight gliders competitively, and the stretchier rubber definitely provides an altitude advantage. It's also lower stress--the stretchier rubber has a slightly slower acceleration, but being over a longer distance, gets you going faster in the end.

On Mon, Jun 29, 2015 at 10:21 PM, gldrgidr@... [BugHLG] <BugHLG@yahoogroups.com> wrote:

I haven't tested this but I have heard it from others.  Normal rubber stretches about three times it's length.  Silicone stretches about 6 times it's length to give the same pull.  This means that you have to pull the silicone high start back twice as far to get the same height.  I'm 65 and  I tend to choose less effort over more.  There's also a matter of needing a longer field.  But you can't beat the price!

Joshua Finn, Ph.D., CFII
Mercer Engineering Research Center
AMA 875391
Isaiah 40:31