Anthony, Mike and All,
Many thanks for the input you are providing, it's the stuff I'm looking for.
I guess I should've painted my scenario in my initial e-mail a little
better.
I'm a performance XC pilot only (not interested in wave, local soaring,
etc), so want to get as much out of the glider as possible. I have a huge
'to-do' list to make this LS1-f into a club class weapon. So initially, I
want to get the polar-curve of this particular glider as is on purchase,
then once the mods are done, compare the results and see how much I've
gained (for the glider, and how much I've gained on the next guy, ie, points
for FREE). Obviously interested to see if there's a 'flat spot' on the
polar (as David Wilson has on his ASW-24) also..
So to answer the questions, and to ask a few more..
* I've got a L-Nav for the electrical vario system.
* I'll be taking maybe 1 x 10,000' tow, or; 2 x 5000' tows - undecided..
* In my spredsheet, I have calculated the pressure and density altitudes.
Not to sure really how they come into play though..
* I thought that all I'm interested in was the IAS, but how does the TAS
come into it..? To balance it all out I suppose..
* After hearing yours and other comments, I think I'll probably shoot for a
time interval at a certain speed. Should I do a 180* turn, then do a 2nd
run at same speed and average the two out?
Thanks again for your input,
Adam Woolley
LS1-f, GWR!
From: "Anthony Smith" <[EMAIL PROTECTED]>
Reply-To: [EMAIL PROTECTED], "Discussion of issues
relating to Soaring in Australia."<[email protected]>
To: "'Discussion of issues relating to Soaring in
Australia.'"<[email protected]>
Subject: RE: [Aus-soaring] Polar Curve Test
Date: Fri, 4 May 2007 19:37:30 +0930
A few thoughts.
What electric vario system are you using? Considering that you probably
want to plug the polar into the vario for speed to fly cues, you can
probably record digital outputs from the electric vario to a laptop or
similar data recorder stashed in the cockpit. I recall an e-mail
conversation with Mike Borgelt where I planned to use a laptop to record
the outputs from the B50 setup in GZQ for exactly this purpose. Would
make things quite easy especially if the sample rate of the vario is
relatively fast.
What height are you doing your test flight(s) at? Are you calculating
your polar to sea level conditions (most polars are)? If so, are you
correcting your indicated airspeed to true airspeed somewhere in your
spreadsheet? I have a simple density ratio calculator (regrettably at
work at the moment) that will help. It works better if you have a
record of outside air temp too.
Your test flight will be ruined by any vertical air movement. Best time
is for dawn with nil wind. I hope you have a tuggy who likes early
mornings!
If you are doing the recording manually ie writing things down in the
cockpit, you are better off recording height loss over a certain time
(stopwatch mounted on inst panel) as opposed to a certain distance
covered. This will make things more accurate at higher speeds. If you
are using your altimeter for height, do you have an inst panel vibrator?
It helps reduce inaccuracy caused by the mechanism sticking in the
altimeter (you tap the altimeter and the needle jumps up or down) over
small height changes.
I am sure that there will be people who were involved with Platypus
testing that may be able to help.
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Adam
Woolley
Sent: Friday, 4 May 2007 6:59 PM
To: [email protected]
Subject: [Aus-soaring] Polar Curve Test
G'day All,
First on the cards is a Polar Curve Test for my LS1-f. On a day off, I
played around with designing a polar curve excel spreadsheet (please
find
attached).
Has anyone got any pointers for flight testing? Does the spreadsheet
that
I've put together look about right? Maybe the legs need to be a bit
longer?
Looking forward to your input, as many others maybe able to benifit.
Regards
Adam
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