Aircraft is a -6A, with wheel pants and fairings installed.
Pitot and static system leak free, and seem to be reasonably accurate in level flight.
I am using the "FLIGHT TESTING HOMEBUILT AIRCRAFT" by Askue, and the "ILLUSTRATED GUIDE TO AERODYNAMICS" by Smith as the reference documentation for the performance testing of the aircraft.
I was expecting to see a fairly simple line graph plot of descent velocity, -fpm, (converted to glide ratio) vs airspeed. My plotted numbers do no look anything like I was expecting.
Flight conditions were as follows: max gross weight, Density Altitude = 4,980 ft. Flaps UP. Engine at idle. Slow to 80knots indicated and start the glide test.
As the airspeed stabilizes and the descent rate stabilizes, record the numbers and slow to the next IAS. Repeat...
Here are the numbers:
IAS(knots) Descent Rate (fpm)
85 650
80 700
75 700
70 650
65 700
60 650
58 full stall
When the numbers are plotted out on a graph, I end up with a sine wave sort of plot, with several minimum descent rates at different IAS numbers.
Does this make any sense?? I think I understand how to get Minimum Sink Rate and Max Distance Glide from a smooth plot curve, but not from the data /plots I have captured. Anyone have any words of wisdom here??
I have also performed this flight test at max gross weight, FULL FLAPS, same density altitude. Although the numbers are different, they follow the same general trend of plotting a sine wave of -fpm vs IAS.
Oh, as a comment, I have two different ASI installed. One is a standard Van's round steam gauge, the other is a Dynon D10A. All of the numbers presented are from the steam gauge. It is the one I use because it is easier for me to read. The Dynon unit presents more accurate info at the lower end of the dial, but it to follows the sine wave numbers when plotted out...just different numbers. The actual Stall point according to the D10A is 53 knots w/ flaps up.
Pitot and static system leak free, and seem to be reasonably accurate in level flight.
I am using the "FLIGHT TESTING HOMEBUILT AIRCRAFT" by Askue, and the "ILLUSTRATED GUIDE TO AERODYNAMICS" by Smith as the reference documentation for the performance testing of the aircraft.
I was expecting to see a fairly simple line graph plot of descent velocity, -fpm, (converted to glide ratio) vs airspeed. My plotted numbers do no look anything like I was expecting.
Flight conditions were as follows: max gross weight, Density Altitude = 4,980 ft. Flaps UP. Engine at idle. Slow to 80knots indicated and start the glide test.
As the airspeed stabilizes and the descent rate stabilizes, record the numbers and slow to the next IAS. Repeat...
Here are the numbers:
IAS(knots) Descent Rate (fpm)
85 650
80 700
75 700
70 650
65 700
60 650
58 full stall
When the numbers are plotted out on a graph, I end up with a sine wave sort of plot, with several minimum descent rates at different IAS numbers.
Does this make any sense?? I think I understand how to get Minimum Sink Rate and Max Distance Glide from a smooth plot curve, but not from the data /plots I have captured. Anyone have any words of wisdom here??
I have also performed this flight test at max gross weight, FULL FLAPS, same density altitude. Although the numbers are different, they follow the same general trend of plotting a sine wave of -fpm vs IAS.
Oh, as a comment, I have two different ASI installed. One is a standard Van's round steam gauge, the other is a Dynon D10A. All of the numbers presented are from the steam gauge. It is the one I use because it is easier for me to read. The Dynon unit presents more accurate info at the lower end of the dial, but it to follows the sine wave numbers when plotted out...just different numbers. The actual Stall point according to the D10A is 53 knots w/ flaps up.