New 29 Palms Winchfest Video

Bill Daniels wrote:
"Marc Ramsey" wrote in message
et...
Bill Daniels wrote:
"Martin Gregorie" wrote:
I tried it enough times when I was pre-solo, thanks, in both ASK-21 and
Puchacz. Didn't work with them. The only effect I remember it having was
breaking a weak link with the Puchacz in a gust.

I did experience a small speed drop today, also in the Puchacz as it
happens, but from the rate and amount of the decrease that was the
driver adjusting the power by making a small reduction at around 500 ft.
After that the remainder of the launch was smack on Vwinch (59 kts)
until he chopped power at the top and we floated off at 55 kts.

We have two Supacats. One has a 240 hp Deutz aircooled diesel V8
industrial engine and the second a big diesel straight six, probably
around 180 hp: I think we were using the straight six winch today. Both
winches drive the drums with a custom gearbox, in turn driven through a
fluid clutch. There are no gear changes during a launch. AFAIK the
gearbox does the following:
- reduction gear. Drum speed is less than engine RPM (of course)
- drum selection (its a two drum winch)
- oscillating drive for the pay-on system


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
Keep trying it. I think you will find you have control over airspeed.
180 - 240 HP isn't nearly enough power to prevent a big 2-seat glider
from slowing the winch.
I assume Martin flies at the Cambridge Gliding Centre. Their V8 Supacat
could not be slowed by pulling (and in fact sped up at times) through
multiple attempts by myself and an instructor (both of us in the 200+ lb
range) in one of their ASK-21s. The only otherwise unusual outcome was a
premature back release late in one launch. This was done with prior
knowledge and discussion of the fact that it should theoretically be
possible. I'd guess there is no overcoming gobs of torque...

Marc

As I said, try it again with careful observation. You will find it works
though you may have to wait a bit to see the effect.

As I said, we discussed ahead of time what would happen if we were to
pull harder (for a normal launch, only a small amount of back pressure
was needed). We were observing carefully and tried holding the stick on
the back stop for a good portion of the climb. We obviously didn't have
a huge amount of elevator authority (forward CG from two heavy guys), so
maybe we just couldn't generate enough lift on a cold autumn day to
exceed the power output of the winch. Or, perhaps you are used to
winches that are underpowered...

Marc

Marc Ramsey wrote:
As I said, we discussed ahead of time what would happen if we were to
pull harder (for a normal launch, only a small amount of back pressure
was needed). We were observing carefully and tried holding the stick on
the back stop for a good portion of the climb. We obviously didn't have
a huge amount of elevator authority (forward CG from two heavy guys), so
maybe we just couldn't generate enough lift on a cold autumn day to
exceed the power output of the winch. Or, perhaps you are used to
winches that are underpowered...

By the way, I absolutely do not claim to be any sort of winch launch
expert. I am interested in reviving ground launch locally, was in the
UK on business, and chose a number of clubs to visit based primarily on
their winch launch operations. I trained according to BGA standards,
and was signed off to solo on the winch at a couple of clubs. I also
received some training in winch driving, talked to anyone who would
listen, and was generally impressed with equipment and the procedures used.

I recommend that anyone who is interested in using a winch in the US do
the same, we have a lot to learn here...

Marc