Auto-Towing - why is this not more popular?

Chapter 3 of the classic American Soaring Handbook has about 23 pages on Auto Tow with several illustrations including a homebuilt car tow release and a technical discussion of the process. 3,500' of runway is the minimum runway length suggested so the sailplane can (barely) make a 360 degree circle to land. Straight-line auto tow and auto tow with pulley are discussed in detail.

As simple as it appears, auto tow should be carefully researched. Finding a sailplane pilot who has supervised auto tow is essential. A ground-launch endorsement from an authorized CFI per FAR 61.31(j) is required for the sailplane pilot unless "grandfathered" however proficiency is essential for both the pilot and the driver. An observer in the auto is important for safety. Density altitude will affect the power of the auto motor and the speed required for the sailplane to launch.

One possible issue with auto tow on airports with airplane traffic is that the cable cannot be reeled in unless a winch system is mounted on the back of a pick-up truck. Some of the hang glider folks have developed this system.

Read the article in the May-June 1955 SOARING magazine, "The Elimination of Guess-Work in Auto Towing" by Otto Zauner and Art Heavener.

The American Soaring Handbook was a binder of 10 chapters on essential aspects that a SSA club needed to know about maintenance, auto, winch and aerotow launching, instruments and much more. Long out of print this handy 6"x9" blue binder might be found on dusty bookshelves in gliderport clubhouses around the USA. Often listed on E-bay and internet book searches such as Albris, this valuable collection of knowledge written by some of the legends of soaring is essential reading. About $25 if all of the 10 chapters are included in the binder.

For an entertaining (but not instructional) video of auto tow watch the "Reunion" episode of the '50's Sci-Fi TV show, "One Step Beyond".

Two excellent posts above from Roy and Burt. I learned partially on auto tow, with maybe 25 launches done by that method over the space of two winters (we would put the towplane away for the winter and revert to auto towing).. Roy summarizes the operational aspects beautifully. As far as equipment, we used "junker" big-block American iron from the early and mid 1970s. The Oldsmobile Custom Cruiser wagon was ideal, since it has a built-in observer seat in the rear. We found that for whatever reason, auto-towing seemed to put a lot of wear and tear on the transition and drive train. Moderately hard acceleration with the load of the glider followed by near-panic stopping repeatedly at the other end meant that I got to be a pretty decent auto mechanic. At our facility, we had 3,000 foot paved with 800 or so grass overrun. With the glider's tail right in the weeds, the car was just on the runway. That gave us the full 3,000 to accelerate, cruise, then stop. We normally got about 600 feet of altitude, though 700 or even 800 was possible if the wind was right down the runway.

So, it's definitely a viable option, especially for early training. Practically, we ended up getting maybe 8-10 launches during a session before something broke on the vehicle or we had a big rope break. We spent a lot of time fixing per every minute of aviating, but when you're in college, $5 tows are attractive!

Erik Mann (P3)

At 11:24 05 October 2015, Burt Compton - Marfa Gliders, west Texas wrote:
Chapter 3 of the classic American Soaring Handbook has about 23 pages on
Au=
to Tow with several illustrations including a homebuilt car tow release
and=
a technical discussion of the process. 3,500' of runway is the minimum
ru=
nway length suggested so the sailplane can (barely) make a 360 degree
circl=
e to land. Straight-line auto tow and auto tow with pulley are discussed
i=
n detail. =20

As simple as it appears, auto tow should be carefully researched. Finding
a=
sailplane pilot who has supervised auto tow is essential. A
ground-launch=
endorsement from an authorized CFI per FAR 61.31(j) is required for the
sa=
ilplane pilot unless "grandfathered" however proficiency is essential for
b=
oth the pilot and the driver. An observer in the auto is important for
saf=
ety. Density altitude will affect the power of the auto motor and the
spee=
d required for the sailplane to launch.

One possible issue with auto tow on airports with airplane traffic is
that
=
the cable cannot be reeled in unless a winch system is mounted on the
back
=
of a pick-up truck. Some of the hang glider folks have developed this
syst=
em.=20

Read the article in the May-June 1955 SOARING magazine, "The Elimination
of=
Guess-Work in Auto Towing" by Otto Zauner and Art Heavener. =20

The American Soaring Handbook was a binder of 10 chapters on essential
aspe=
cts that a SSA club needed to know about maintenance, auto, winch and
aerot=
ow launching, instruments and much more. Long out of print this handy
6"x9=
" blue binder might be found on dusty bookshelves in gliderport
clubhouses
=
around the USA. Often listed on E-bay and internet book searches such as
A=
lbris, this valuable collection of knowledge written by some of the
legends=
of soaring is essential reading. About $25 if all of the 10 chapters
are
=
included in the binder.

For an entertaining (but not instructional) video of auto tow watch the
"Re=
union" episode of the '50's Sci-Fi TV show, "One Step Beyond".
Yep, my dad was the glider pilot and I was the tow car driver . I was
fifteen then. Ross

Ross Briegleb

Hi Sean
The Dublin Gliding Club is doing every year an expedition to the Beaches on the Dingle Peninsula in the South of Ireland where gliders are car towed see enclosed or others on You Tube
https://vimeo.com/108137453

Regards
Bruno

On Monday, October 5, 2015 at 12:57:33 AM UTC-4, Sean Fidler wrote:
I had an interesting conversation with a pal about auto-tow glider launching method recently. It seems academic really.

When cost is considered, auto-towing has to be far more affordable than even winching. Maybe $1.50 per tow, max? In aviation, the cost is always critical. Especially in gliding club environments. Aerotows are $30-50 per tow. Winches are extremely expensive to purchase, to maintain, and insure and require skilled operators.

Auto-tow procedure seems fairly simple. 1) Steady strong acceleration until the glider comes airborne, then 2) add 5mph and 3) hold that speed until you hear differently from the pilot. Of course, 4) stop at the end of the runway :-).

Why is auto-towing not a mainstream method of getting gliders airborne?

I saw auto-towing happen regularly at Hobbs this year (my first visit). It was quite graceful and almost exotic. To be honest, it looks even more fun than winching.

I am very interested in learning what you know, your thoughts and your opinions.

Sean
7T

It's only as economical as your space and labor happens to be. Ideal for a dry lake. Hobbs is sort of a paved dry lake :-).

When I was a student pilot, we did 2-33 "cat shots" off Harris Hill with two old tow ropes spliced together, later with a proper 400' cable, into gentle late afternoon ridge lift, all powered by an old 307 Chevelle with questionable brakes (thanks Dave!). A total gas, never to be forgotten. Driving the car (which I did a lot) was even more exciting than flying the glider.. The brow of the hill slopes off in a fashion that makes the nerves a little uneasy... especially with those rusty four wheel drum brakes.

-Evan Ludeman / T8

On Monday, October 5, 2015 at 8:30:06 AM UTC-4, Tango Eight wrote:

When I was a student pilot, we did 2-33 "cat shots" off Harris Hill with two old tow ropes spliced together, later with a proper 400' cable, into gentle late afternoon ridge lift, all powered by an old 307 Chevelle with questionable brakes (thanks Dave!). A total gas, never to be forgotten. Driving the car (which I did a lot) was even more exciting than flying the glider. The brow of the hill slopes off in a fashion that makes the nerves a little uneasy... especially with those rusty four wheel drum brakes.

-Evan Ludeman / T8

That reminded me. The far end of our runway had a steep dropoff into a corn field. On one tow, as I eased off the gas and got on the brakes... there weren't any. Or not much. Went all Dukes of Hazard and luckily landed safely on the downslope, ending up with the hood in the corn. Funny now, but actually a pretty dicey situation. So driver/observer safety in the tow vehicle is definitely another consideration depending on the field conditions/configuration.

On Monday, October 5, 2015 at 7:40:06 AM UTC-5, Papa3 wrote:
On Monday, October 5, 2015 at 8:30:06 AM UTC-4, Tango Eight wrote:

When I was a student pilot, we did 2-33 "cat shots" off Harris Hill with two old tow ropes spliced together, later with a proper 400' cable, into gentle late afternoon ridge lift, all powered by an old 307 Chevelle with questionable brakes (thanks Dave!). A total gas, never to be forgotten. Driving the car (which I did a lot) was even more exciting than flying the glider. The brow of the hill slopes off in a fashion that makes the nerves a little uneasy... especially with those rusty four wheel drum brakes.

-Evan Ludeman / T8

That reminded me. The far end of our runway had a steep dropoff into a corn field. On one tow, as I eased off the gas and got on the brakes... there weren't any. Or not much. Went all Dukes of Hazard and luckily landed safely on the downslope, ending up with the hood in the corn. Funny now, but actually a pretty dicey situation. So driver/observer safety in the tow vehicle is definitely another consideration depending on the field conditions/configuration.

All the winches I flew on in Europe had guillotines to cut the cable in an emergency (mandated in Germany). How do you do that with cars? I witnessed a near fatal accident with hanglider being towed by a car where the pilot flew a neat arc that ended with an impact. When I asked the person on the bed of the towing pickup how he had planned to sever the rope in such an event, he showed me his pocket knife!

On Monday, October 5, 2015 at 10:11:57 AM UTC-4, wrote:


All the winches I flew on in Europe had guillotines to cut the cable in an emergency (mandated in Germany). How do you do that with cars? I witnessed a near fatal accident with hanglider being towed by a car where the pilot flew a neat arc that ended with an impact. When I asked the person on the bed of the towing pickup how he had planned to sever the rope in such an event, he showed me his pocket knife!

We had a very nice rig for that. The car end had Schweizer tow release mounted on a steel plate. The plate was hinged for freedom in the vertical axis. The plate and associated structure was mounted on a ball coupling that rode on the car's towball, allowing freedom in the horizontal axis. The rig had the usual Schweizer release rope (same as a towplane), so the back seat observer held the release rope in his hand and pulled it in an emergency. We also had a crash-ax mounted in back as an extra safety measure.

On Monday, October 5, 2015 at 10:11:57 AM UTC-4, wrote:
On Monday, October 5, 2015 at 7:40:06 AM UTC-5, Papa3 wrote:
On Monday, October 5, 2015 at 8:30:06 AM UTC-4, Tango Eight wrote:

When I was a student pilot, we did 2-33 "cat shots" off Harris Hill with two old tow ropes spliced together, later with a proper 400' cable, into gentle late afternoon ridge lift, all powered by an old 307 Chevelle with questionable brakes (thanks Dave!). A total gas, never to be forgotten. Driving the car (which I did a lot) was even more exciting than flying the glider. The brow of the hill slopes off in a fashion that makes the nerves a little uneasy... especially with those rusty four wheel drum brakes.

-Evan Ludeman / T8

That reminded me. The far end of our runway had a steep dropoff into a corn field. On one tow, as I eased off the gas and got on the brakes... there weren't any. Or not much. Went all Dukes of Hazard and luckily landed safely on the downslope, ending up with the hood in the corn. Funny now, but actually a pretty dicey situation. So driver/observer safety in the tow vehicle is definitely another consideration depending on the field conditions/configuration.

All the winches I flew on in Europe had guillotines to cut the cable in an emergency (mandated in Germany). How do you do that with cars?

We had a Schweizer tow hook mounted in place of a hitch ball.

-Evan

On Monday, October 5, 2015 at 9:11:57 AM UTC-5, wrote:

All the winches I flew on in Europe had guillotines to cut the cable in an emergency (mandated in Germany). How do you do that with cars? I witnessed a near fatal accident with hanglider being towed by a car where the pilot flew a neat arc that ended with an impact. When I asked the person on the bed of the towing pickup how he had planned to sever the rope in such an event, he showed me his pocket knife!

Yikes! Like the others, we have a Schweizer hitch on a swivel so it is always line up with the rope tension, and a cable or cord to operate it. On my setup, I also have a hydraulic cylinder between the car and the hitch, with a gauge up front so I can see line tension and use this to help set the right speed.

Steve Leonard