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Static Towing (ST)

Postby Bill Cummings » Tue Feb 18, 2014 7:49 pm

US Hawks Training Manual Project. (DRAFT)
Static Tow (ST) foot launching.

The first thing to do is to read everything you can get your hands on.
The second thing is to reread everything you can get your hands on.
Third thing is hook up with a USHPA instructor.
http://www.ushpa.aero/

The author started hang gliding towing in January of 1978. This was before the USHGA developed a towing manual. Back in those days of towing a pilot used a stainless steel control frame.
As the towing sport evolved towing went from attaching the tow bridle to the stainless steel control frame (Base tube and down tubes juncture) to using a Center of Mass, Skyting Tow Bridle.
The Skyting Bridle attached about 18” ahead of the heart bolt on the keel tube and the other part of the Skyting Bridle attached to the pilots body near the waist area passing underneath the base tube. The bridle was designed to apply one third of the tow force to the glider at the keel and the remaining two thirds tow force applied to the pilot. This tow force split was also referred to as a 2 to 1 or (2/1) bridle.
Later on pilots tried a 1/1 tow bridle. This will also get you into the air. The tow ratios look different so you can safely assume that the tow up will be different.

Towing from the control frame when compared to towing with the newer Skyting Bridle made controlling the glider comparable to steering a large truck with a blown power steering pump or controlling a car with power steering. The center of mass method made towing about four times easer.

For different reasons (And some not being very good.) pilots decided to alter towing bridles for reasons of parasitic drag, aesthetics, different towing methods like aero towing (AT), platform launching (PL), and static towing (ST).
Scooter tow training, also ST towing, has moved to towing in some areas of the world by attaching the combination tow/release bridle to the pilot over the base tube and in some cases both over and under the base tube.
Some have even hooked to the pilot only and under the base tube. This is not a good idea. (More on this later.)
With each modification of a tow bridle for different methods of towing a new tow pilot must realize that we always have to stay within an operational envelope.
Basically we understand that we should not fly too slow or too fast so that we are able to maintain good control.
How we hook a pilot and glider to a towline can alter which end of the operational envelope we will find ourselves.

For example, hooking directly to a single point release on the harness of the pilot after having passed the towline underneath the base tube of the control frame is the best method for platform launching. However if a pilot chose to run off the launch from the ground and not use the platform launch that would be choosing the worst attachment method for static towing alone or also incorporating a pay out winch/reel.
I will attempt to explain why but if it isn’t self evident to a beginning pilot at this point this will be one of many examples why you shouldn’t attempt to teach yourself how to tow launch. Having a knowledgeable instructor is of the utmost importance.

Most of us were taught that running across the street without looking both ways could really mess up our day. Having been taught that lesson and the ramifications of disregarding it we were more readily convinced that running with scissors or while looking through a hand held telescope was something also to avoid.

Not having a climb restricting “V” bridle, 2/1 Skyting bridle, or 1/1 bridle while Static Towing (ST) puts the pilot at the mercy of the tow operator and the wind.

Tow pilots refer to a term, “Being locked out over the top.” as a situation where the pilot can not shift their weight far enough forward to stop a climb while under tow. This can happen very easily if there is too much tow line tension or there is a steep wind gradient near the ground. Towing into a thermal can add to this lock out over the top.

Being locked out over the top also increases your odds of progressing into a lock out to the left or right. With a slow climb rate the “sweet spot,” down wind of the tow vehicle, is quite wide. The glider is able to move to the left or right of the tow vehicle much farther without getting locked out left or right. The more tension or the faster the climb the narrower the “sweet spot,” becomes.
I’ll add this left and right lock out example here then get back to the over the top lock out information.

For example if you have a slight cross wind from the left on your tow road and you hold your flight directly over the road this will be holding a position that has you closer to a lock out to the left. You may be doing just fine but if the wind is greater as you get higher and your tow vehicle (static) doesn’t slow down to maintain the same line tension the sweet spot will narrow. You will also be climbing faster due to having more line tension. The tow vehicle not slowing down to compensate for the greater wind speed at altitude can be the cause or your lock out to the left even though you are still holding position directly over the tow road.

In this situation a beginning tow pilot might think to themselves that they are locking out to the left now but I was still over the tow road and I didn’t do anything to cause this!
You didn’t do anything is correct. But -- when the headwind increased as you gained altitude that increased the line tension. You didn’t get the nose down to reduce the line tension. Your sweet spot narrowed. Even worse than that would have you using a tow bridle that would impede your effort to get the nose down.

Choosing from different bridles or attachment points can determine whether your pitch control is good, bad, or inadequate.

Going back to the over the top lock out now if you have a bridle that allows you to lower the nose to slow the climb rate you will have just widened your sweet spot. The sweet spot is the area left and right and downwind of your tow vehicle that you can safely operate in.

If however you are low to the ground and have too much line tension and are being towed under the control bar and the tow line is attached to the pilot only --
Well now, just the thought of this will send shivers up and down the spine of any instructor that knows what he is doing.

If this primer was news to anyone then take my word for it -- hook up with a tow instructor and don’t try towing a hang glider on your own. Oh, and don’t forget to look both ways!
Bill Cummings
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Re: Static Towing (ST)

Postby Bob Kuczewski » Fri Feb 21, 2014 12:43 pm

billcummings wrote:The first thing to do is to read everything you can get your hands on.
The second thing is to reread everything you can get your hands on.
Third thing is hook up with a USHPA instructor.
http://www.ushpa.aero/


Good advice Bill!!

I hope to someday have US Hawks instructors, but right now, your comment about getting with a USHPA instructor is still one of the best things a new pilot can do.

:clap: :clap: :clap: :clap: :clap:
Join a National Hang Gliding Organization: US Hawks at ushawks.org
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Re: Static Towing & tow line recovery chutes.

Postby Bill Cummings » Wed Jun 22, 2016 6:56 pm

The fix for a tow line recovery chute causing a hang glider pilot to crash is becoming a lost art.
With the advent of YouTube one would think visuals would be getting the word out how to avoid problems but that doesn't look to be the case.
While towing, pilots have had towline recovery chutes blossom open and then the pilot overtook the chute and it became tangled either with the pilot or the glider and sometimes both.

Pilots overtaking their blossomed towline recovery chutes have ended up being towed by their helmets, lip boom microphone, vario, training wheel, reserve parachute safety pin, harness mounted radio, hall wind speed meter, GPS, downtube/basetube junction wing nut, the hook knife handle, the ballistic recovery chute handle and less often, several of these during one event.

The spectrum usually runs somewhere between, extremely unfortunate and dangerous to deadly.
On the low end would be tangling with your helmet. You could still basically be close to center of mass towing in this situation. However towing by the handle of your ballistic recovery parachute may be less desirable center of mass towing. It's a tough call. Which would you prefer?

On the other end of the spectrum towing from an instrument located at the corner of your control frame is way worse than a center of mass snag when tension is restored. (For sure it will progress into a lockout.)
The multiplying factor for this emergency depends on where your release and/or weak link is located.

There are ways to eliminate a blossoming line recovery chute and most readers have already thought of the 100% fix.
I prefer not to use one.
There are far better ideas being used than a towline recovery chute that stays collapsed because you are towing through it.
Just pause and think. What are all the possibilities that you can think of that could cause tension to come off of the towline while under tow? -------------
If you find yourself about to tow on a tow rig belonging to someone else that uses a towline recovery chute; has that owner done anything to mitigate the blossoming of the chute when tension comes off of the tow line before you release?
There are several different methods that are being used or have been used to fix this problem. At this time I want to pause and brainstorm on the Hang Gliding General thread for any new better ideas or revive some of the old ones then come back to this training thread with a list of the best ideas. There is no need at this time to be towing with ideas that have been tossed out, with cause, years ago.
Bill Cummings
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Re: Static Towing (ST)

Postby Bill Cummings » Thu Jul 20, 2017 9:09 pm

A lonely country road for static towing is nice to have close to home.
One vehicle passing by per hour can be annoying if you're broke down and need help
but if you're towing that same volume of traffic can be annoying on the other end of the scale.
The trick is to try and reduce as many obstructions as possible and get some airtime.
It doesn't seem to be that a perfect flying site exists anywhere. There is always room for improvement.
This post is about impediment mitigation as it relates to static towing (ST).
Many issues back the USHGA or was it in the USHPA magazine there was an article about
mitigating towline obstructions along a road in the form of state, county, or township road signs.
The concern was that the towline as a result of a crosswind to the road could cause the towline to come in
contact with a sign on the shoulder of the road. Some shapes like a warning sign would not create
as big of a problem with a towline as a rectangular speed limit sign; or stop sign.
sign #2.JPG
sign #2.JPG (31.17 KiB) Viewed 117 times

sign #3.JPG
sign #3.JPG (23.95 KiB) Viewed 117 times

Some shapes allow the towline to slide up and clear the sign while others would
catch the towline under it.
The article had the tow crew standing a piece of PVC up along side the sign to allow the towline to slide up the PVC and not catch under the sign. They cut a slot length wise in the PVC to allow the edge of the sign to slip into the slot. They taped the PVC to the sign. (I would use clear packaging tape.)
For the base of the PVC pipe they would pound a larger diameter steel pipe into the ground to leave there and be a socket for the PVC to be inserted down into the steel pipe. The socket pipe was pounded completely down so that its top was flush with the ground.
This could still end up with you getting a ticket by taping to a road sign but if you take the PVC and tape home with you at the end of each towing day you will probably get by.
Bill Cummings
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