First Glider

Mark James Boyd wrote:

And Jeff, keep in mind some of the performance is just from the
retract wheel. Really I wouldn't buy into a fixed gear glider unless
it was a Sparrowhawk. In the end, if the retract idea is scary,
just leave the gear down! Tie-wrap it that way if you like!

Believe me, you'll outgrow fixed gear quickly...

THis might not be obvious, but a glider designed with fixed gear doesn't
suffer the same performance penalty a retractable gear glider does when
the gear is down. THe typical fixed gear does not extend as far from the
fuselage as on a retractable gear glider, and it is faired in properly,
so the drag is negligible at thermalling and moderate speeds and small
at higher speeds.

Because a nonretracting gear is typically on lower performance gliders,
I think people come to believe it is a big performance liability. These
gliders would still be lower performance with the gear tucked away. For
example, note the small handicap difference between these two Russias
(US handicap):

AviaStroitel Russia AC-4A 1.193 (fixed gear)
AviaStroitel Russia AC-4C 1.185 (retract gear)

Or the SAME handicap for the two versions of the Phoebus:

Bolkow Phoebus A, B 1.025 (A is fixed; B is retract)

What the retractable gear can give a designer is flexibility in other
aspects. The glider can sit higher off the ground for better wing and
fuselage clearance in a off-airport landing, and more "crush space" is
available for absorbing very heavy landing loads.

Of course, the designer might choose a gear high enough that wing tip
stalling on the ground roll is a problem, or not use the crush space
effectively (cheaper). You will definitely pay more for the retractable
gear because they are more costly to design and build, and some of us
will pay more for fixing the glider when they forget to lower the gear
or it makes it's own decision about retracting!


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Eric Greenwell
Washington State
USA

Eric Greenwell wrote:
Mark James Boyd wrote:

And Jeff, keep in mind some of the performance is just from the
retract wheel. Really I wouldn't buy into a fixed gear glider unless
it was a Sparrowhawk. In the end, if the retract idea is scary,
just leave the gear down! Tie-wrap it that way if you like!

Believe me, you'll outgrow fixed gear quickly...

THis might not be obvious, but a glider designed with fixed gear doesn't
suffer the same performance penalty a retractable gear glider does when
the gear is down. THe typical fixed gear does not extend as far from the
fuselage as on a retractable gear glider, and it is faired in properly,
so the drag is negligible at thermalling and moderate speeds and small
at higher speeds.

This is all quite true. A Russia with gear down will fly worse than
a fixed gear Russia (at the same weight).

I was really just making the point that if retract gear familiarity
is the issue, it's certainly possible to fly for a while and get
familiar with other aspects of the glider before mucking with
learning the retract gear procedures...

Because a nonretracting gear is typically on lower performance gliders,
I think people come to believe it is a big performance liability. These
gliders would still be lower performance with the gear tucked away. For
example, note the small handicap difference between these two Russias
(US handicap):

AviaStroitel Russia AC-4A 1.193 (fixed gear)
AviaStroitel Russia AC-4C 1.185 (retract gear)

I disagree completely. Sure, the handicap difference looks small.
This is bunk. There is a big difference in performance between these
two gliders in even moderate (4 knot) conditions. And in wave or
strong ridge lift? The polar at 80 knots is about 15% better for the
retract. I'd be willing to bet that two evenly ranked pilots,
one in each, would prove that the AC-4c is better. Swap them
out every other day, and you'd see the AC-4c win a competition.

I think the AC-4c is mishandicapped. It won Sport class at
Avenal this year, and Chad Moore took third in a 2000 competition
despite missing a day!

You can make up for not having flaps to some degree by using
ballast, but a big draggy tire (or TWO!) has no fix except gettin'
it out of the wind...again, the Sparrowhawk may be an exception because
adding the mechanism and space for retract might involve other
needed changes that subsequently reduce performance...
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Mark J. Boyd