From: petri@venus.iucf.indiana.edu (HOWARD PETRI)
Subject: Speed to Fly ( was: Soaring decisions (was: ...long boring flights)
News-Software: VAX/VMS VNEWS 1.3-4   
Reply-To: petri@venus.iucf.indiana.edu
Organization: INDIANA U. CYCLOTRON FACILITY, BLOOMINGTON, IN
Distribution:  world
Date: Wed, 9 Sep 1992 23:09:28 GMT

In article <9209091544.AA10540@lri.uwo.ca>, Michael Steckner <steckner@lri.uwo.ca> writes...
>     For those who have studied speed to fly, well, it is great,
>but it also should be pointed out that the error introduced by flying
>too slow or too fast is negligible (unless you are really fly the wrong
>speed by a *HUGE* margin. Check out Reichmann, Xcountry book). 
>The theory is that Mac watched the weather (dont forget, he is a 
>meteorologist by training) whereas the others watched the varios and 
>ASI. Right or wrong, it makes for a cute story.
> 
     This is quite true and there are rules of thumb that work about as
well as the calculations. I believe it was George Moffet that said that one 
needed only to fly at a speed that produced a rate of sink equivalent
to one's average rate of climb in thermals. He won races using this 
simple strategy. 

     I got Reichmann's Cross Country Soaring book early in my Soaring
career. I guess I am still early in my soaring career; going on 6 years
now. Anyway; I was quite impressed with the mathematical development
and decided to implement his equations in a computer program and generate
the data needed to make a Stocker final glide calculator using my favorite
polar. I did this and was quite proud of myself. In 1990 Reichmann came
to the US soaring convention and I had a chance to talk to him as I have
mentioned before. I told him how I had done all of this work and he 
looked at me rather unimpressed and said something like,

" well yes that is all very good, but you know that the correct speed to fly
is only about 5% of the total equation. The other 95% is choosing the correct
path over the ground!"

      This very properly deflated my ego as I realized he was of course
correct. If one continually chooses the wrong place to look for thermals
and lift, flying to these places at the correct speed is totally
useless. And this is where the successful cross country soaring pilots
really shine. They have a sixth sense for choosing the correct path to
the next region of lift, while the rest of us only hope. Reichmann had
no suggestions as to how I might develop this less mathematical but very 
necessary skill.

     Well if any soaring pilots would like to take advantage of my 
already written program; send me your favorite polar and I will fit it
and run it through the Stocker calculation. You can then make your
own personalized Stocker Final Glide Calculator. This is really a
nice device to have since it is made using a map of the area you
are flying in and one sees exactly the altitude needed to get back
to the airport from your present location.

     Now, you would think that knowing all of this I could get that 
300 km goal out and return done. Oh well conditions have really been
lousy in the midwest this year. Yeah, that's it!

Howard Petri
Pegasus N599JH 

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