Bill Daniels wrote:
"Bruce" wrote in message
...
Bill Daniels wrote:
This comment is solely about trainer L/D and not this specific trainer.

L/D IS important especially if you operate from a field where nearby
landings are hazardous. Students ( and for that matter some instructors)
aren't good at judging just how far they can glide. In this situation,
extra performance is what gets them home after a mis-judgement. L/D then
becomes a safety factor.

There's no downside to training in higher performance unless the
instructor THINKS there is. If the instructor is afraid of high
performance gliders, he will pass that fear on to his students.

Bill Daniels

wrote in message
ups.com...
for a trainer 40:1 is plenty. heck 18:1 is plenty, as proven by the
multitudes of pilots trained in 2-22 and 2-33 Schweizers over the
years. We're not talking about an open class nationals competitor
here.


I agree conditionally.

This is one area where the old crates make better trainers, as the
difference in effective glide ratio is much more affected by wind. The
safe circuit differs markedly with a 1:26 L/D and a wind component that
can be a significant fraction of stall speed. So it is easier to teach the
mental calculations required, and when to draw the line in terms of the -
Is it safe to launch? decision.

How so? A 2-33 stalls (really) at about 40 MPH. My Nimbus 2C stalls at
38mph and I can turn inside a 1-26 if the ballast tanks are dry. If I open
the dive brakes to the point they want to rest, the Nimbus 2C glides about
like a 2-22. If I open them all the way it's 1:1 at 55mph.

Perhaps I was unclear here. The low performance trainer typically has a limited
speed range it can fly in. If the wind factor is a significant fraction of stall
speed then you have a lot less speed range available. For example maneuvering
speed in a Bergfalke II/55 is only 120km/h - it stalls at ~60km/h. At 120km/h
the L/D is such that you can just about fly a circuit without leaving the
vertical confines of the runway. You can get the same L/D with a glass ship, but
you can't emulate the ultra low wingloading, and high drag airframe. All the
penetration of a well thrown newspaper.


A higher penetration , higher performance trainer makes the distances
involved a little bigger, so they may be harder to judge. In this instance
I believe higher performance may lower safety.

Yes harder, but the errors will be on the safe side - i.e. the HP glider
will go farther than the student is willing to believe.

True - the higher performance trainer generally has a safety advantage (more
options and greater margin, better control)- but the bigger distances mean more
exposure to variable conditions. Have watched someone fail to make it back to
the runway because of complacency by instructor. From the close in circuit the
low performance guys were doing he would have been able to reach the alternate
runway when the wind picked up. From further out, the time exposed to the
headwind put him in a no - win situation.


The downside of training exclusively in low performance gliders is that
transition to even a moderate performance single seater is more difficult.

You bet! And once you have created the mind set that higher performance
glider are difficult to fly - they WILL be more difficult to fly for that
student.

Bill Daniels


Many of my worst habits come from learning my initial judgment in a vintage. I
know I'm not gifted, but the transition from a Bergfalke to a 15m standard class
single seater was interesting...
That is why I like the K21 so much. Similar performance to the kind of single
seater many students will move up to - and a pleasure to fly.