HP-11/Sisu Polar

Mike,

Feb 1971 Soaring has a Paul Bikle article called 'Flight
Test Performance Summary' that includes data from a
1960 test of the Sisu 1 N7983A performed by Niemi and
Johnston and published in the Feb !961 Soaring. It
also has data from a test of Sisu 1A N1100Z performed
by Roberts in 1963.

The two polars reported were very different. The Sisu
1 at 660 lb + 6.11lb/ft2 was:

Best LD 40.5 at 53knots
Min sink 126ft/min at 48knots
Sink rates:
147fpm at 40knots
128 @ 50
158 @ 60
219 @ 70
299 @ 80
392 @ 90
499 @ 100
A surprisingly good polar for that era!

The Sisu 1A measured at the higher weight of 730lbs
and 6.75lb/ft2 was worse at all speeds:

LD 36.5 at 50knots
Min sink 135fpm at 45 knots
145fpm @ 40knots
139 @ 50
185 @ 60
257 @ 70
353 @ 80
470 @ 90
614 @ 100

Both gliders were reported to have the same span and
airfoil and both had been smoothed and filled. There
is a note 'Sisu performance with flaps below 48knots'
- presumably both gliders.

There is reference to an HP 8 test done in 1958 but
nothing for an HP11

John Galloway



At 07:00 16 February 2005, wrote:
Does anyone have a decent polar or any type of performance
figures for
either an HP-11a or Sisu? All leads are greatly appreciated.

Thanks,
Mike