Wing Launch - Can it pull your wings off?

Derek C wrote:
The consequence of using a 10% weaker link would be a greater chance
of a broken weak link and a failed launch, which might be hazardous in
itself under some circumstances.

No, never! A cable brake is routine and *never* hazardous in *any*
circumstances. If it is, then something in your operation is seriously
flawed.

But a cable brake (or weak link brake) is always an annoyance, as it
interrupts the operation.

On Aug 14, 11:30*am, John Smith wrote:
Derek C wrote:
The consequence of using a 10% weaker link would be a greater chance
of a broken weak link and a failed launch, which might be hazardous in
itself under some circumstances.

No, never! A cable brake is routine and *never* hazardous in *any*
circumstances. If it is, then something in your operation is seriously
flawed.

Depends on the size and nature of the airfield. Our site at Lasham in
the UK is large and flat, and gives you a wide range of options after
a winch launch failure. I have flown at a small sloping German site
where they launched without a weak link because having a weak link
failure was considered a serious hazard. Having said that the speed
control and quality of their winch launches was very good.

Derek C

Derek C wrote:
On Aug 14, 11:30 am, John wrote:

No, never! A cable brake is routine and *never* hazardous in *any*
circumstances. If it is, then something in your operation is seriously
flawed.

Depends on the size and nature of the airfield. Our site at Lasham in
the UK is large and flat, and gives you a wide range of options after
a winch launch failure. I have flown at a small sloping German site
where they launched without a weak link because having a weak link
failure was considered a serious hazard.

Hmmmmm... I've experienced firsthand a fair number of rope brakes on the
winch (but interestingly not a single weak link break), and hence
consider a rope break pretty much SOP when winching. So I'm not sure I'd
want to fly at that German site. I have no problem with an airfield
where a cable brake puts me in a difficult situation which requires
special procedures but a cable brake shall never be hazardous.

On Aug 14, 5:24*pm, John Smith wrote:
Derek C wrote:
On Aug 14, 11:30 am, John *wrote:
No, never! A cable brake is routine and *never* hazardous in *any*
circumstances. If it is, then something in your operation is seriously
flawed.

Depends on the size and nature of the airfield. Our site at Lasham in
the UK is large and flat, and gives you a wide range of options after
a winch launch failure. I have flown at a small sloping German site
where they launched without a weak link because having a weak link
failure was considered a serious hazard.

Hmmmmm... I've experienced firsthand a fair number of rope brakes on the
winch (but interestingly not a single weak link break), and hence
consider a rope break pretty much SOP when winching. So I'm not sure I'd
want to fly at that German site. I have no problem with an airfield
where a cable brake puts me in a difficult situation which requires
special procedures but a cable brake shall never be hazardous.

The site in question is a narrow strip 800 metres long, sloping
downhill at about 1 in 10, on top of a hill and totally surrounded by
small unlandable vineyards. They always launched downhill,
irrespective of wind direction. Once above about 200ft, but below
circuit height, the only cable break option to get back onto site was
a 180 degree turn (teardrop circuit) to land back uphill. The
alternatives were a controlled crash into a vineyard or a water
landing on the local river.

I have also winch launched at a very small UK site called Sandhill
Farm near Shrivenham in Wiltshire, which wasn't much better. At
certain heights you only option was to land in one of the surrounding
fields. They have since given up winch launching as they felt that the
risk to reward (700-800ft launches) ratio was too great.

The only problem with winch launching (of which I am a great fan) is
that you need a reasonable large airfield to get decent heights and to
do it safely without presenting pilots with extremely critical
judgement decisions in the event of a launch failure.

Derek C

Derek C wrote:
The site in question is a narrow strip 800 metres long, sloping
downhill at about 1 in 10, on top of a hill and totally surrounded by
small unlandable vineyards. They always launched downhill,
irrespective of wind direction. Once above about 200ft, but below
circuit height, the only cable break option to get back onto site was
a 180 degree turn (teardrop circuit) to land back uphill.

And where's the problem?

On Sun, 15 Aug 2010 10:12:03 +0200, John Smith
wrote:

Derek C wrote:
The site in question is a narrow strip 800 metres long, sloping
downhill at about 1 in 10, on top of a hill and totally surrounded by
small unlandable vineyards. They always launched downhill,
irrespective of wind direction. Once above about 200ft, but below
circuit height, the only cable break option to get back onto site was
a 180 degree turn (teardrop circuit) to land back uphill.

And where's the problem?

The timing.


With such a short field it might be necessary to execute this teardrop
circuit at very low altitude because it's not possible anymore to land
straight-on.

Little error margin for finding the right compromise between executing
the turn ionto final at a healthy altitude and not too close to the
airfield.

It's definitely more relaxed to execute this teardrop circuit at
300ft+.


Cheers
Andreas

On Aug 15, 7:51*pm, Andreas Maurer wrote:
On Sun, 15 Aug 2010 10:12:03 +0200, John Smith

wrote:
Derek C wrote:
The site in question is a narrow strip 800 metres long, sloping
downhill at about 1 in 10, on top of a hill and totally surrounded by
small unlandable vineyards. They always launched downhill,
irrespective of wind direction. Once above about 200ft, but below
circuit height, the only cable break option to get back onto site was
a 180 degree turn (teardrop circuit) to land back uphill.

And where's the problem?

The timing.

With such a short field it might be necessary to execute this teardrop
circuit at very low altitude because it's not possible anymore to land
straight-on.

Little error margin for finding the right compromise between executing
the turn ionto final at a healthy altitude and not too close to the
airfield.

It's definitely more relaxed to execute this teardrop circuit at
300ft+.

Cheers
Andreas

Here is a video of a German pilot getting a teardrop circuit wrong
after an 80 metre (about 250ft) cable break:

http://www.youtube.com/watch?v=_xCct...os=zqLm5HhNvPc

Derek C

On 8/14/2010 8:17 AM, Derek C wrote:
On Aug 14, 11:30 am, John wrote:
Derek C wrote:
The consequence of using a 10% weaker link would be a greater chance
of a broken weak link and a failed launch, which might be hazardous in
itself under some circumstances.

No, never! A cable break is routine and *never* hazardous in *any*
circumstances. If it is, then something in your operation is seriously
flawed.

Depends on the size and nature of the airfield. Our site at Lasham in
the UK is large and flat, and gives you a wide range of options after
a winch launch failure. I have flown at a small sloping German site
where they launched without a weak link because having a weak link
failure was considered a serious hazard. Having said that the speed
control and quality of their winch launches was very good.

Derek C

Out of genuine curiosity, can you share more details of "small sloping...site"?

I have difficulty imagining a winch site unsuitable for either a straight
ahead landing following an 'early-early' launch problem not also suitable for
a 360-to-a-return-at-the-launch-point for a 'later-in-time' launch problem. I
am assuming a 'reasonably powered winch' of course, which I imagine is the
German norm. Short of an anemic winch with the winch/line stashed down a road
in a copse of woods, my imagination fails me here.

My experience in the western U.S. (generally 5000' msl) is any field
considered 'distance-suitable' for (even marginal) aerotowing is - in a
launch-emergency sense - far more 'emergency-option-friendly' than aerotowing,
because you never get dragged at low altitude over completely unlandable
terrain...which is definitely *not* the case in these parts with aerotowing.
Are there folks winch launching from postage-stamp-sized-fields surrounded by
unlandable terrain using a beyond-the-boundary-winch?

Curiously,
Bob W.

On Aug 15, 2:23*pm, Bob Whelan wrote:
Are there folks winch launching from postage-stamp-sized-fields surrounded by
unlandable terrain using a beyond-the-boundary-winch?

The site where I converted to winch launching was like that. It's
"Jury Hill", at Greytown, near Wellington NZ.

There is a quite long north/south runway, but the interesting
conditions are often in westerly winds. The westerly runway starts
from the southern end of the main runway and at the time I was flying
there had a length of around 300 - 400 m. The winch run was something
like 1200 m with the remainder of the distance to the winch crossing a
mixture of swamp and low "sand dunes" (not actually sand, but
similarly lumpy). The cable retrieve vehicle used a not terribly
straight path through the lumps, including crossing a farm track and
one or two small streams.

With a glider with good brakes (e.g. Ka7, ASK13) and a bit of a
headwind (and you wouldn't use that runway unless there was too much
crosswind for the other one) you could land straight ahead from a
cable break at 200 or 250 ft and make some kind of circuit from 200 ft
or less, so there was always either one good option or else two
reasonable ones for the same runway, plus the option of simply turning
right 90 degrees onto the 1000+ m runway and land with a crosswind.

On Aug 14, 3:30*am, John Smith wrote:

No, never! A cable brake is routine and *never* hazardous in *any*
circumstances...

I do envy your faith in the ubiquity of human competence.

Thanks, Bob K.