Sgs 1-35 Polars for SeeYou Mobile

A friend of mine has a Schweizer 1-35 and we need to find the
correct polar numbers to put into his SeeYou Mobile program.

Thanks for your help.

Randy

http://talihinasoaring.com/

On Mar 31, 8:14*pm, Randy wrote:
A friend of mine has a Schweizer 1-35 and we need to find the
correct polar numbers to put into his SeeYou Mobile program.

Thanks for your help.

Randy

http://talihinasoaring.com/


Randy,

I would use the flight test info Dick Johnson measured for two 1-35's.
Found on the SSA website.

Mike

Mike,
I do not understand what to enter on the SeeYou Mobile
Polar setting page. There are six available boxes.
Name Sgs 1-35
Min Load - 6.38
Stall Speed - 43 mph
a -
b -
c -

I do not know what goes in a, b, c boxes.
Even when I look at the polars for my own
glider, I do not understand what the numbers
mean.

Hi,

I have a Schweizer 1-35A polar on my Polars page.
http://www.cumulus-soaring.com/polars.htm

That page also has some spreadsheets that can be used to calculate the a, b
and c coefficients used by SeeYou and SeeYou Mobile. You can enter your own
polar data into the spreadsheets or use the polar data from the web site.

The page also has 3 pairs of airspeed and sink rate for very glider type
which can be used in SeeYou on the PC to calculate the SeeYou a, b, and c
coefficients.

Best Regards,

Paul Remde
Cumulus Soaring, Inc.

"Randy" wrote in message
...
A friend of mine has a Schweizer 1-35 and we need to find the
correct polar numbers to put into his SeeYou Mobile program.

Thanks for your help.

Randy

http://talihinasoaring.com/

On Mar 31, 9:50*pm, Randy wrote:
Mike,
I do not understand what to enter on the SeeYou Mobile
Polar setting page. There are six available boxes.
Name Sgs 1-35
Min Load - 6.38
Stall Speed - 43 mph
a -
b -
c -

I do not know what goes in a, b, c boxes.
Even when I look at the polars for my own
glider, I do not understand what the numbers
mean.

Randy,

I do not use See You mobile but the three entries should allow for
sink rate at speed- in metric. If there are entry windows for both
sink rate and speed, then...

a-Best L/D or L/D sink rate and the speed it happens or
36.8-1 L/D or sink of .7 m/s @ 92 kph


b-Two meter sink rate and speed it happens or
2 m/s @ 148 kph

c-one higher speed sink rate/speed setting, say 3 meter/sec.
3 m/s @ 176 kph

These numbers should be close and work ok as far as an accurate
polar.

Mike

On Mar 31, 9:50*pm, Randy wrote:
Mike,
I do not understand what to enter on the SeeYou Mobile
Polar setting page. There are six available boxes.
Name Sgs 1-35
Min Load - 6.38
Stall Speed - 43 mph
a -
b -
c -

I do not know what goes in a, b, c boxes.
Even when I look at the polars for my own
glider, I do not understand what the numbers
mean.

If I entered the data correctly into Paul's spreadsheet, and the
conversion from a cambridge file to a See you file is correct, the
data supplied by Dick Johnson's actual test polar at his weight is ...

a= 2.1
b= -4.4
c= 3.2

Hi Mike,

Those numbers look like they may be correct. Hopefully, when you enter
those numbers into SeeYou Mobile, it displays the correct glide ratio and
other data.

If you send me the 3 airspeed and sink rate pairs (with the lowest speed one
at the best L/D speed). I would be glad to put them onto my Polars web
site. I will also need to know the wing loading at which the numbers were
obtained.

Best Regards,

Paul Remde

"Mike" wrote in message
...
On Mar 31, 9:50 pm, Randy wrote:
Mike,
I do not understand what to enter on the SeeYou Mobile
Polar setting page. There are six available boxes.
Name Sgs 1-35
Min Load - 6.38
Stall Speed - 43 mph
a -
b -
c -

I do not know what goes in a, b, c boxes.
Even when I look at the polars for my own
glider, I do not understand what the numbers
mean.

If I entered the data correctly into Paul's spreadsheet, and the
conversion from a cambridge file to a See you file is correct, the
data supplied by Dick Johnson's actual test polar at his weight is ...

a= 2.1
b= -4.4
c= 3.2

On Mar 31, 10:14*pm, Randy wrote:
A friend of mine has a Schweizer 1-35 and we need to find the
correct polar numbers to put into his SeeYou Mobile program.

Check which of the three models of 1-35 it is. Numbers for a "C"
that doesn't retract are different. There are very clear graphs of the
polars updated in 2002 in the latest Flight Manual. There are not
too many "A" models, so I'm not sure about that one since the Flight
Manual doesn't specify differences in the polar. See
http://members.goldengate.net/~tmren...5/types135.htm

I use the following numbers are for a "regular" 1-35 with a
retractable wheel. The numbers are good for final glides from 5 nm
out, dry @ 685# (We have low cloud bases here) I use
"SoarPilot," but a polar is a polar. Your mileage may vary given the
wide range of wing finishes I've seen on 1-35's.

53 kts -1.42 kts
82 kts -3.5 kts
109 kts -7.58

Be careful with that "stall speed" number. It can vary from 30 kts to
56 kts, depending on model, flap settings, and ballast. Check page 10
of the Flight Manual.

ms

On Apr 1, 6:13*am, AGL wrote:
On Mar 31, 10:14*pm, Randy wrote:

A friend of mine has a Schweizer 1-35 and we need to find the
correct polar numbers to put into his SeeYou Mobile program.

Check which of the three models of 1-35 it is. * Numbers for a "C"
that doesn't retract are different. There are very clear graphs of the
polars updated in 2002 in the latest Flight Manual. * There are not
too many "A" models, so I'm not sure about that one since the Flight
Manual doesn't specify differences in the polar. *Seehttp://members.goldengate.net/~tmrent/soar/docs/135/types135.htm

I use the following numbers are for a "regular" 1-35 with a
retractable wheel. The numbers are good for final glides from 5 nm
out, dry @ 685# * * (We have low cloud bases here) * I use
"SoarPilot," but a polar is a polar. *Your mileage may vary given the
wide range of wing finishes I've seen on 1-35's.

53 kts *-1.42 kts
82 kts -3.5 kts
109 kts -7.58

Be careful with that "stall speed" number. *It can vary from 30 kts to
56 kts, depending on model, flap settings, and ballast. *Check page 10
of the Flight Manual.

ms

Wow - be careful what you put into your glide calculator. You have a
lot riding on it, like your butt.

First of all, units matter. SeeYou accepts as settings a variety of
units for airspeed and vertical speed. The manual doesn't appear to
say this explicitly, but I believe you need to enter coefficients for
the polar derived from the same system of units you specify in
SeeYou's settings.

Second, a,b and c are the coefficients of a quadratic curve that is a
best fit for the glider polar. You generate this quadratic by picking
three points off the polar - preferably for speeds that you typically
fly. Best L/D, medium cruise, fast cruise, for example. Pick speeds
for no water ballast - the computer can figure out the ballast
effects. The three pairs of speeds, plugged into the generic quadratic
formula y=ax^2+bx+c will give you three equations with three unknowns,
which you can solve using high school algebra. I suspect this is what
Paul's spreadsheet does.

If you are using knots as the units for airspeed and vertical speed
then the above pairs of polar coordinates yield:

a -0.0014
b 0.1197
c -3.7796

This gives a polar with a best L/D of 37 at 52 knots, an L/D of 25 at
80 knots and an L/D of 17 at 100 knots.

You should check the calculations and figures yourself to ensure they
are correct as I have not looked at a polar directly and it's your
friend's but that will end up short of the airfield on final glide if
there are errors in the data or the math.

Hope that helps,

9B

Paul,

Actually I entered the data in your conversion spreadsheet as a
Cambridge Polar File and then posted the resulting See You data
points.

Using the best L/D and speed and the 2 meter sink rate at speed, when
I checked the resulting generated polar, it was pretty close to the
Johnson measured polar. Close enough that I would fly with it.

Best L/D was actually measured at 36.8 @ 92 kph and the 2 meter sink
speed @ 148kph. Test weight was 315.2 kg.





On Apr 1, 6:13*am, "Paul Remde" wrote:
Hi Mike,

Those numbers look like they may be correct. *Hopefully, when you enter
those numbers into SeeYou Mobile, it displays the correct glide ratio and
other data.

If you send me the 3 airspeed and sink rate pairs (with the lowest speed one
at the best L/D speed). *I would be glad to put them onto my Polars web
site. *I will also need to know the wing loading at which the numbers were
obtained.

Best Regards,

Paul Remde

"Mike" wrote in message

...
On Mar 31, 9:50 pm, Randy wrote:

Mike,
I do not understand what to enter on the SeeYou Mobile
Polar setting page. There are six available boxes.
Name Sgs 1-35
Min Load - 6.38
Stall Speed - 43 mph
a -
b -
c -

I do not know what goes in a, b, c boxes.
Even when I look at the polars for my own
glider, I do not understand what the numbers
mean.

If I entered the data correctly into Paul's spreadsheet, and the
conversion from a cambridge file to a See you *file is correct, the
data supplied by Dick Johnson's actual test polar at his weight is ...

a= 2.1
b= -4.4
c= 3.2