I my less than successful experiments in cold weather flying would
agree with Tapio's data. In talking with my physics professor the
other day,(he flys some rubber models as well) that because
complications that arise in testing the models predicated on theories
rarely hold visibly true due to an over layering of unaccounted
variables. ... And this coming from a guy that makes a living modeling
everything mathematically:-p
Nick
On 2/26/07, Fred Tellier <fred-tellier_at_cogeco.ca> wrote:
>
>
>
>
>
>
> Good info Tapio, I think that the flight times in Slanic agree with your
> values. I did tests on 5-99 in preparation for the 2002 WC at Slanic and got
> similar drops in power between my normal testing temperature of 20 to 22 deg
> C and testing at 10 deg C. I did this both in my back yard ( in the shade)
> at 10 deg and in Mark Schaefer's cave in Dayton at around 50 deg F. What was
> strange was the turns and maximum torque were not that different but the
> foot pounds per pound value was down. I did not run enough tests to create
> the kind of data that Garry would like to have but the results were
> definitely there. I always wanted to do the same tests at 30 deg C but never
> got around to it, and the only rubber I used was 5-99 as it is all I use in
> competitions.
>
> By the way Tapio, how is your F1M flying these days and did you get your
> VPs working?
>
> To those of you who haven't met him, Tapio attended USIC and West Badin
> with us a few years back while he was living in Canada working on his PHD
> degree. We did some serious F1M flying at both meets.
>
> Fred Tellier
>
> ----- Original Message -----
> From: Tapio Linkosalo
> To: Indoor_Construction_at_yahoogroups.com
> Sent: Monday, February 26, 2007 6:10 AM
> Subject: Re: [Indoor_Construction] Flight Temperature
>
> On Mon, 26 Feb 2007 dgbj_at_aol.com wrote:
>
> > This temperature difference would make a 4 or 5 percent difference in
> energy
> > (about 0.3% per Fahrenheit degree). The energy relations for rubber must
> be
> > calculated on an absolute temperature scale. There is not a 15% energy
> > difference between the temperatures you mentioned.
>
> Wrong. The figures that I quoted were normalized from the slope parameter
> of the regression model fitted to measured data (also other data points
> than 15C and 30C). For a regression model it makes no difference where the
> zero point of the temperature scale lies, any interval scale on X-axis
> (the independent variable) will do. The 10% difference in energy return
> between 15C and 30C is a correct value, and is actually observed in the
> measured data, not just derived from the regression model. It may be
> questioned, however, for what temperature range the reduction of the
> energy return remains linear. Definately this will NOT apply down to
> absolute zero, and also the increase in energy return will saturate
> somewhere between 30 and 40C, above which the rubber will get too soft to
> store the energy.
>
> -Tapio-
>
> [Non-text portions of this message have been removed]
>
>
Received on Mon Feb 26 2007 - 11:39:46 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:44 CET