Re: Re: 40% Stab size or 20%?

From: Don Slusarczyk <don_at_slusarczyk.com>
Date: Sat, 23 Oct 2010 14:15:11 -0400

Yes but look at the Cl values generated with such high posts, I believe
they go very high. Also be aware that the formulas used to calculate
downwash are formulas for full size aircraft and some effects/assumtions
used to make those equations may not translate well to our lower speeds.
But it was all that was available. Someone needs to put an indoor model
in a wind tunnel and get some data on downwash angles in regards to
wing aspect ratio and angle of attack then the program can be fine tuned
more. Treat the spreadsheet as living document and can always be
improved and refined especially as rubber and VP technology improves.

I have found the CG and SM calcs to be very helpful in many events.
Flight times especially for models like F1D, HLS, Int Stick, and EZB
were all pretty much as expected. Some events are a bit off in predicted
flight time and further study is needed on those models that fly at
faster speeds and use lighter rubber etc to get better estimates on
flight prediction.

Don


> This kind of thing still amazes me. Now I've got to start playing with it again.
>
> I gave up last time when increasing the wing post length on one of the spreadsheets kept improving the time, even past 50".
>
> BTW - I added a row on my copy for "Approx VP time corrected for low rubber ratio", "=B64*B84". That made the F1D-55 times for my current model pretty accurate.
>
> ---
Received on Sat Oct 23 2010 - 11:15:20 CEST