Re: Data points for INAV submission?

From: <mkirda_at_sbcglobal.net>
Date: Sun, 16 Dec 2012 14:37:47 -0000

Hi Leo.

Estimates range from .6 to .7 meters per second. My models, being heavier and not as well trimmed, fly slightly faster than this.

I plan to do some in-flight measurement during the next Racine flying session. It will give me an idea how accurate the above is.

Given the above .67 m/s, 45 RPMs, and flying in Racine at 72 degrees, all of the props have a very similar local chord widths and very similar Reynolds numbers, roughly 2000 at either end going to around 4000 at mid-point.

Thanks for the formula - I will try to generate a table using it with the express caveat that measurement of actual flight speed is best.

Regards.
Mike Kirda

--- In Indoor_Construction_at_yahoogroups.com, "Leo Pilachowski" <leop@...> wrote:
>
>
>
> Here is the formula I use to calculate the approximate flying speed of our models. I try to check actual flying speed which can vary greatly with the trim of the model. This fact is important to remember.
>
> Speed in meters per second =
> square root[(160 &#8727; weight in grams)/(wing area in sq.cm)]
>
> This is for monoplanes. For biplanes, one cannot use double the wing area since the two wings do not act separately. I assume that a biplane flying speed is about 5% slower than the calculated speed for a the plane with just one wing (use the area of the larger wing). This seems to work out in practice at least for my observations.
>
> One might also think that for planes with larger stab areas (tandems) that one should count the stab area, too. However, in practice it does not seem to make much difference as a plane is nearly always trimmed with more proportionate lift on the wing (cg moved forward of the neutral point) for pitch stability.
>
> BTW, what speed do you use for an F1D?
>
> Leo
>
> --- In Indoor_Construction_at_yahoogroups.com, "mkirda@" <mkirda@> wrote:
> >
> > Also thinking that it might be useful to include an estimated flying speed for some various classes. However I have no idea what those might be outside of F1D.
> >
> > LPP/F1M
> > A6
> > Low Weight EZB
> > F1L
> > 35cm
> > HLS - Probably very similar to F1D?
> >
> > Regards.
> > Mike Kirda
> >
>
Received on Sun Dec 16 2012 - 06:37:49 CET