Polar

Where we go out and actually try to measure our speed and accompanying sink rate (Quest Air, Groveland, Florida, USA)

http://ozreport.com/12.079#1

You'll find the polars as published by the manufacturers (and massaged a bit by me) in the article above.  Given that FlyChart (http://flytec.com/Products/Software.htm) has a great little create-a-polar-from-a-test-flight application, I thought that I would go out early in the morning and do a flight to see if I could generate a polar.  I did this years ago on the ATOS at Wallaby Ranch, but I didn't have the nice FlyChart polar application then and had to write my own least squares fit to a polar curve.

Last Tuesday, Joe, an early riser, pulled me up on my Wills Wing T2C 144 to 5,000' at about 7:20 AM.  Sunrise was 6:42 AM (http://aa.usno.navy.mil/data/docs/RS_OneDay.php).  The idea was to maintain a given airspeed for about 30 seconds.  I had my Flytec 6030 set for a two second recording interval.

It is hard to maintain an airspeed for 30 seconds I discovered.  Also it is hard to maintain a high airspeed, at least I found that to be the case.  Anything over 50 mph was difficult.  Dustin says that it is no problem with his version of the Wills Wing T2 144.

I had the VG on about 7/8th's.  I hook in at about 210 pounds.  I left the VG on whether I was flying slow or fast.  I was in my Moyes Matrix Race harness and I kept my head down as much as possible.  (I did have my head pulley on.) I kept my arms close to my sides.

This is the polar curve (red line) I get from the data using the automatic curve fitting:

Click on above to get the high resolution version.

The shape of this curves wasn't very much like a polar curve, so I used the built in tools in FlyChart to "manually" fit a polar curve to the same data.  This is what I got:

Click on above to get the high resolution version.

It turned out that this curve was very similar to the one I created from the Wills Wing web site and data (see the URL above for more on that).  So it appears as though I've in a "general" way confirmed that the Wills Wing T2 polar values that I gave earlier are about right.

I'm hoping that I can get other pilots to fly polars using my 6030.  I have "calibrated" the airspeed just comparing it with my car's speedometer, so who knows how close it is to "reality." But if we all use the same instrument without making any changes it should be a reasonable comparison.  Dustin says he'll do it.  Maybe I can convince Jonny to do it also.

You can see the data (and the "error bars") above.  If someone wants the actual data, you can download it here.

Discuss Polar at the Oz Report forum   link»