Safety of winch launch vrs. aero tow?

A related remembrance...

Years ago I attended a mid-summer's eve cookout at Ridge Soaring in
central PA. For entertainment we were armchairing the end o'day
training flights. A glider released just after take-off, landing at
the far end of the field. The tow plane landed, then taxied down to
launch the glider in the opposite direction. As the tug passed us,
2-33 in tow, KS asked what was going on. I explained that a series of
rope breaks were practiced as a student got close to solo. They had
just completed a straight ahead release and recovery and would now
practice a 180 for return to the runway. As the tow plane and glider
reached 20 feet above the ground, still short of the runway boundary,
Karl said, "Now! It would be hairy, but you could do it."

Karl and a handfull of other pilots probably could. The rest of us
wait until we have enough altitude to more than measure the sins we're
likely to commit as the emergency unfolds -- 200 feet being an
appropriate indulgence.

For those who need to know to the inch, don't forget to include 35% of
your wingspan, lest you bury a tip. And don't forget that anytime the
controls are not neutral, your sink rate goes well below the arc of
the polar.

So far, of the math I've seen, success would only be achieved for
gliders of zero span requiring no control input (and resulting drag)
to initiate a bank or roll out of it.

"Chris OCallaghan" wrote in message
om...
A related remembrance...

Years ago I attended a mid-summer's eve cookout at Ridge Soaring in
central PA. For entertainment we were armchairing the end o'day
training flights. A glider released just after take-off, landing at
the far end of the field. The tow plane landed, then taxied down to
launch the glider in the opposite direction. As the tug passed us,
2-33 in tow, KS asked what was going on. I explained that a series of
rope breaks were practiced as a student got close to solo. They had
just completed a straight ahead release and recovery and would now
practice a 180 for return to the runway. As the tow plane and glider
reached 20 feet above the ground, still short of the runway boundary,
Karl said, "Now! It would be hairy, but you could do it."

Karl and a handfull of other pilots probably could. The rest of us
wait until we have enough altitude to more than measure the sins we're
likely to commit as the emergency unfolds -- 200 feet being an
appropriate indulgence.

For those who need to know to the inch, don't forget to include 35% of
your wingspan, lest you bury a tip. And don't forget that anytime the
controls are not neutral, your sink rate goes well below the arc of
the polar.

So far, of the math I've seen, success would only be achieved for
gliders of zero span requiring no control input (and resulting drag)
to initiate a bank or roll out of it.

Not to belabor the obvious, but a 180 return to the runway from a 200 foot
airtow rope break is not always possible. We tend to talk as if it were
true but if believe it, we may be setting up a disaster. With a heavy
glider, weak tug, high density altitude and unfavorable wind (and maybe a
thick headed tug pilot) you may need as much as 1000 feet to be in a
position for a safe return to the airfield.

There have been many occasions when my left hand hovered near the release in
preparation for a simulated rope break. But, looking back over my shoulder
at the airfield, I thought, "I don't theeenk so" and let the student
continue.

Over the last year a young friend of mine (A CFI-G) suffered two low
altitude rope breaks (weak link failures) and each incident resulted in an
off-airfield landing. (To his credit - no damage)

Bill Daniels

Frank Whiteley wrote[snip]
There once was a non-BGA soaring site/club in East Anglia in the UK. The
operator was named Fred, but the surname escapes me and I believe he
passed
away in the 1980's. By all accounts he operated a steam winch [snip]

Freddie Wiseman was the man, and the winch was not steam powered, but
diesel. It was remarkable in that it was a converted combine harvester.
I have a photo of it somewhere. I saw it working. It was rather low
powered, and operated via huge canvas belt drives which were
"interesting". Not technology I would suggest repeating elsewhere.

The site was Ridgewell (ex 381st BG base 1943-45), where I now fly
from - see http://www.essexgliding.org/index.htm

The winch was fairly lethal, potentially - I knew one of the drivers who
had to contend with a broken cable still under power thrashing around in
the cab. After Freddie's death in 1984 a few people revived the club
and continued to use the combine winch until 1988. When my club bought
the site the winch was still intact and was brought back, but we decided
not to use it and instead bought other winches. The only time I know of
using it in our time was as a towing vehicle, when we moved two huts and
the tractors got bogged down (don't ask - it's a long story). It did
the rescue but burnt out its clutch in the process. It was eventually
scrapped about three years ago.

Relevance to the subject line - it was dangerous to the operator, but
never hurt a pilot - instead gave lots of practice, as is only right, in
"premature terminations of launch" and "too low in circuit".

Chris N.

in article et, Bill
Daniels at wrote on 2003/10/31 11:39:



...a 180 return to the runway from a 200 foot airtow rope break
is not always possible.

...you may need as much as 1000 feet to be in a position for
a safe return to the airfield.

...two low altitude rope breaks (weak link failures) and...resulted
in...off-airfield landing[s].


More specifics please for those off-airport landings. Otherwise your "1000
feet" may be taken by some as a bit of an exageration.



Jack

"Jack" wrote in message
...
in article et, Bill
Daniels at wrote on 2003/10/31 11:39:



...a 180 return to the runway from a 200 foot airtow rope break
is not always possible.

...you may need as much as 1000 feet to be in a position for
a safe return to the airfield.

...two low altitude rope breaks (weak link failures) and...resulted
in...off-airfield landing[s].


More specifics please for those off-airport landings. Otherwise your "1000
feet" may be taken by some as a bit of an exageration.



Jack


In my friends case, the first break came shortly after crossing the field
boundary at about 50 feet. This was a case of insufficient climb angle to
reach 200 feet while still in range of the runway. The other, as I
understand it, was at about 300 feet but still out of gliding range of the
airport.

My comment about 1000 feet referred to a situation that happened to me
because the tug pilot turned downwind at 100 feet AGL with a heavy glider
and strayed still further downwind as the air tow ground on despite urgent
radio calls. It was only at 1000 feet AGL that I felt that I could release
and get back. (and get another tug pilot) This has happened to me too many
times to recall all of them.

Understand, I fly in an area where density altitude at takeoff can exceed
10,000 feet. It takes a strong tug to keep a heavy two seater constantly in
range of the runway.

My point with the original post is that there is no guarantee that the magic
200 feet AGL will always get you back.

Bill Daniels

in article . net, Bill
Daniels at wrote on 2003/10/31 19:45:


"Jack" wrote in message
...

More specifics please for those off-airport landings. Otherwise your "1000
feet" may be taken by some as a bit of an exaggeration.
[i]
...in an area where density altitude at takeoff can exceed
10,000 feet...t takes a strong tug to keep a heavy two seater
constantly in range of the runway.

...there is no guarantee that the magic 200 feet AGL will
always get you back.

Very good point, and thanks much for the additional information.

You have a much greater challenge then we do here at DA ~2000 feet. The
winds here make every day different.



Jack

Indeed, aerotow can sometimes be interesting! Some years ago I was flying in
a local club competition and found myself behind an underpowered Rallye,
piloted by a man with a recently diagnosed heart condition who therefore
needed a safety pilot with him. (Yes, I know the correct response is to
refuse the tow, but competitions soften the safety cells in the brain, even
local club competitions).

We climbed (very slowly) to 400ft and then stayed there while we flew in a
straight line at least 3 miles from the airfield. It's the only time I've
been field spotting on tow for such a long time.

Not suprisingly, I failed to soar once we reached the release height of
2,000 ft (partly because I only had time for once centreing turn if I was to
remain within gliding range of the field). My relight was a winch launch!

"Bill Daniels" wrote in message
ink.net...

"Chris OCallaghan" wrote in message
om...
A related remembrance...

Years ago I attended a mid-summer's eve cookout at Ridge Soaring in
central PA. For entertainment we were armchairing the end o'day
training flights. A glider released just after take-off, landing at
the far end of the field. The tow plane landed, then taxied down to
launch the glider in the opposite direction. As the tug passed us,
2-33 in tow, KS asked what was going on. I explained that a series of
rope breaks were practiced as a student got close to solo. They had
just completed a straight ahead release and recovery and would now
practice a 180 for return to the runway. As the tow plane and glider
reached 20 feet above the ground, still short of the runway boundary,
Karl said, "Now! It would be hairy, but you could do it."

Karl and a handfull of other pilots probably could. The rest of us
wait until we have enough altitude to more than measure the sins we're
likely to commit as the emergency unfolds -- 200 feet being an
appropriate indulgence.

For those who need to know to the inch, don't forget to include 35% of
your wingspan, lest you bury a tip. And don't forget that anytime the
controls are not neutral, your sink rate goes well below the arc of
the polar.

So far, of the math I've seen, success would only be achieved for
gliders of zero span requiring no control input (and resulting drag)
to initiate a bank or roll out of it.

Not to belabor the obvious, but a 180 return to the runway from a 200 foot
airtow rope break is not always possible. We tend to talk as if it were
true but if believe it, we may be setting up a disaster. With a heavy
glider, weak tug, high density altitude and unfavorable wind (and maybe a
thick headed tug pilot) you may need as much as 1000 feet to be in a
position for a safe return to the airfield.

There have been many occasions when my left hand hovered near the release
in
preparation for a simulated rope break. But, looking back over my
shoulder
at the airfield, I thought, "I don't theeenk so" and let the student
continue.

Over the last year a young friend of mine (A CFI-G) suffered two low
altitude rope breaks (weak link failures) and each incident resulted in an
off-airfield landing. (To his credit - no damage)

Bill Daniels

Chris Reed wrote:

We climbed (very slowly) to 400ft and then
stayed there while we flew in a straight line at
least 3 miles from the airfield. It's the only time
I've been field spotting on tow for such a long time.

Not suprisingly, I failed to soar once we reached
the release height of 2,000 ft

Was it not possible for you to use the in-air signals to steer the tow pilot
back toward the field?

Should we assume that these two rope breaks were during aero tow?
The next obvious question is how strong were the weak links and
why did they break.

The fact that this individual had two weak links break at a low enough
altitude that it resulted in his landing off field, does make us wonder
what the complete story is. Was he solo in a single place glider? Or
was it a result of letting a student get too far out of position? Inquiring
minds would like to know.

M Eiler

More specifics please for those off-airport landings. Otherwise your
"1000
feet" may be taken by some as a bit of an exageration.
Jack


In my friends case, the first break came shortly after crossing the field
boundary at about 50 feet. This was a case of insufficient climb angle to
reach 200 feet while still in range of the runway. The other, as I
understand it, was at about 300 feet but still out of gliding range of the
airport.

My comment about 1000 feet referred to a situation that happened to me
because the tug pilot turned downwind at 100 feet AGL with a heavy glider
and strayed still further downwind as the air tow ground on despite urgent
radio calls. It was only at 1000 feet AGL that I felt that I could
release
and get back. (and get another tug pilot) This has happened to me too
many
times to recall all of them.

Understand, I fly in an area where density altitude at takeoff can exceed
10,000 feet. It takes a strong tug to keep a heavy two seater constantly
in
range of the runway.

My point with the original post is that there is no guarantee that the
magic
200 feet AGL will always get you back.

Bill Daniels

Those interested in wire launch safety may like to read an article by
John Hoskins, BGA Accident Investigator, which has just been published.

See http://www.gliding.co.uk/bgainfo/saf...s/winching.pdf
or http://www.glidingmagazine.com/ListF...Dtl.asp?id=370 .

There have been many accidents of the types described,
insufficient energy to avoid a heavy landing after a launch failure,
and a spin entry after stalling during the first part of the launch.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.


"Gary Boggs" wrote in message
...

Someone must have already compared the safety of these tow launch methods.
What do the statistics show is the safer method of launch? Aero tow
seems to involve more inherent dangers to me. For one thing, there is
just more time for things to go wrong. What could be more dangerous than
to tie two airplanes together and try to fly?

Gary Boggs