[Frank Colver]

Sure is a lot of stuff to eliminate a motor and propeller from the glider.

Also , the motor vehicle access into motorless areas has come under some argument that goes something like this: A motorless motorcycle or car or truck is still a motor vehicle because it is designed to be solely powered by a motor even if someone is pushing it by hand at the time. However, a bicycle that has a motor mounted for assist but is rendered inoperable at the time by not having on board a battery (if electric) or a fuel tank (if ICE) is not a motor vehicle because it is being powered by human power pedals, for which it was designed.

I have an electric assist mountain bike but I leave the battery home if I'm going to ride in an area approved for bicycles but not motor vehicles. The motor in this case is just dead weight, and inoperable, and the bicycle is being used in accordance with its design purpose of being human powered.

Some areas or states will allow electric powered bicycles to operate under power assist, as bicycles, in areas closed to motor vehicles. California is only part way there at this time. In CA if the electric assist will only operate if the human is also adding pedal power it is then classified as a pure bicycle. But if the bicycle can be operated by electric power alone, without any pedalling input, then it is in the class of a motorcycle. That is where my bike is since I can just push the throttle and ride without pedaling if I choose to. I'm hoping to convert it to the other kind someday.

FC

[reluctantsparrow]

Loving the concept of towing in this manner. far more efficient than a motor with a propeller as far as conversion of energy goes since every ounce of energy expended by the power source (winch) is being directly converted to airspeed for the gliders. NO WASTED energy.
a tremendous portion of a propellers energy is spent beating the air into submission just as a tremendous amount of energy is wasted by a person treading water.
Imagine it this way. Imagine lifting yourself out of the pool my pressing down along the concrete edge of the pool......easily done......now imagine lifting yourself out of the pool by pressing downward on the water itself......nearly impossible unless you are a dolphin.
using this analogy.....I am visualizing an amazingly small amount of force needed to winch two gliders into the air towards each other since the amount of wasted force is going to equal zero. Every ounce of force applied by an onboard winch will be applied to one or the other glider directly....brilliant.

[reluctantsparrow]

Possible Improvement of concept:
Imagine two gliders taking off towards each other as described in the opening statements. Then, as they gain a safe altitude they bank away from each other while the winch is still pulling them towards each other.....
the resulting force would be similar to a slalom water skier who swings to the outside of a turn as the ski boat is turning.....a tremendous increase in speed using the exact same amount of power from the boat......
Imagine two gliders banked away from each other in this manner spiraling upward........ a continued upward spiral......would this work?
Hmmm....I am trying wrap my head around a continued upward spiral right now.....it would very similar to a controlled and unbroken lockout......a lockout usually produces the desirable (in this case) effect of increased speed and increased altitude, followed by the undesirable effect of losing control and nosing over downward into the ground at tremendous speed......but....if all that energy could be transmitted into a cotinued upward spiral????.....an even smaller amount of energy would be required from the winch to maintain this upward dance than towing directly towards each other...
I am trying to visualize two slalom water skiers holding to the same line..... banked away from each other as the line they are clinging to becomes shorter and shorter

[reluctantsparrow]

a continued upward spiral could gain much more altitude with the same length of line being reeled in at a much slower speed (but using the same amount of force from the winch).....then...when the two pilots become too close.....release and easily glide away from each other since they are ALREADY banked to glide away from each other....then, when the line is played out again the two pilots would simply fall into a normal thermaling pattern with each other, begin to reel in the line, and bank away from each other again as line tension is re-acquired.......
This presents a very graceful and easily repeatable pattern in my mind...I see a a very graceful dance between two butterflies spiraling upwards.
by joining the two gliders with a retracting tow line the two gliders plus the retracting tow line are functioning now in much the same manner as a helicopter does, screwing its way up into the atmosphere.
Vision:
I just shared this idea with David Carroll, a very close friend of mine and fellow hang glider pilot who is staying with Susan and I for a week right now. Here is the vision we imagined together if this concept is a workable one.
Spiral your way skyward as the first thermals are starting to pop and cross country flying can begin.
Team fly cross country as far as possible to land in a large enough field or airport that we can tow each other out from again the next morning.
The energy requirements of the extremely small winch required to tow in this manner could be replenished each day by the same Sunshine creating the thermal conditions.....
Two pilots working together in this manner could fly all the way across a continent using the Suns energy that is both creating the thermals and re-charging the device.
sounds like a lot of fun.

[reluctantsparrow]

The fastest reel in of the line would be the initial part of the towing TOWARDS each other.
As the pilots swing into a choreographed spiral the speed requirement of the line being reeled in would DECREASE.
Line tension would INCREASE.
Winch power requirements would stay the same. Think of it as shifting into a lower gear to climb a hill.
I can already see the size of the winch required to tow in this manner in my mind. it is about the size of Those large fishing reels used for ocean fishing.
I am very excited for someone with a degree in engineering to calculate the horsepower and torque requirements for the winch and the amount of force applied to the towline in the spiral pattern.

[reluctantsparrow]

One more aspect contained within the picture painted on the canvas of my mind right now......no solar panel required to recharge this device although maybe at first.....but eventually.....a thin thread woven into the tow line itself to collect solar energy and directly collect the energy required by the winch device while in use.
a thin filament woven into 1,000 feet of tow line is a huge amount of surface area......a very large solar collector.

[reluctantsparrow]

Talked about this today with a couple buddies that have been flying longer than I have......yes...and we are all still alive....amazing...they gave a lot of valuable input....some of which was....
..if a reel-in device with line could be constructed to perform the required task it would definitly be doable in wings with full controls. Full Yaw, pitch, and roll controls.....that was the general consensus of our confab....should work.
A weight shift hang glider however, would be flying in a very narrow window of controlability and possibly on the constant verge of lockout with the upward spiral idea so the more conventional step towing method may be safer and more feasable.....
so...
someone IS going to build this idea for hang gliders someday and they will start off step towing with it....
After that is being done succesfully it will only be a matter of time before two pilots Buddy towing in this manner agree to try the spiral method to see if it can be done with a weight shifted glider with no aerodynamic controls.

[Bill Cummings]

The fastest reel in of the line would be the initial part of the towing TOWARDS each other.
As the pilots swing into a choreographed spiral the speed requirement of the line being reeled in would DECREASE.
Line tension would INCREASE.
Winch power requirements would stay the same. Think of it as shifting into a lower gear to climb a hill.
I can already see the size of the winch required to tow in this manner in my mind. it is about the size of Those large fishing reels used for ocean fishing.
I am very excited for someone with a degree in engineering to calculate the horsepower and torque requirements for the winch and the amount of force applied to the towline in the spiral pattern.

Jim,
I'm going to make some experience estimates or at least impart ball park tension requirements for readers.
My wife, Donnell Hewitt, and I went to Padre Island years back. With several (I could look it up.) hundred feet of rope my wife towed me up with the E-150 van. At around 300' agl the sea breeze was enough for the van to stop and I could kite my hang glider.
Donnell and Terry unhooked me from the release at the van and tied the towline to a stick and with each holding an end of the stick and the towline tied to the middle they walked me along the shoreline. When they returned me to the van Donnell took a picture of Terry alone holding the stick to kite me.
When I saw her about to hook me back up to the release on the back of the van I pushed out on the basetube. That spun Terry around and she had to dig in here heels to handle the extra tension that I put on the line.

Back home in Minnesota, when I was living there, with a pilot towing behind the boat and when not climbing, I could, hand over hand, pull the pilot and glider toward the boat. (not so when climbing.)

Once while kiting behind a snow-machine with the brake set my friend, Don Ray, started to walk on the towline, pushing it into the snow. As he walked me lower below the wind speed I needed to sustain I signaled, faster. He took the rope over his shoulder and started to trudge back to the snow-machine. He was able to stop my decent until he got to the snow-machine. Then he need both hands for the pull starter and work the throttle so I sunk out.
The snow was deep so he had fairly good traction.
I have winch towed with a 70 lb weak-link and went to the top without breaking it. (My strongest one was 350 lbs)
My guess is that while my 130 lb wife could kite me all by herself that it must take somewhere between 30 to 40 lbs just to kite. (Not climb.)
Edit: Oh yes. I just remembered. When kiting and the wind died a little I would cut to the right or left to get higher while the snow-machine was still stopped.

[reluctantsparrow]

Thanks for the valuable input Bill. The fun potential of this concept intrigues me.
Lets say a workable device is constructed (or already exists but currently used by some other application) and this method actually works....
we spiral tow each other up in calm morning conditions. Its going to be a great cross country day but right now conditions are calm. No prevailing wind.
we buddy tow each other up in either the step tow fashion or the spiral fashion (if it works) to around 8 grand but the thermals have not really kicked in yet so we remain connected. we give the line enough slack for one of us to pull a 180.....now we are on course, together, at 8 grand.....we glide down to within a thousand feet off the deck, fall back into the towing pattern, and tow ourselves up again to 8 grand to continue our journey....we do this repeatedly until conditions become strong enough to sustain good thermal flying for the rest of the day....thats when one of us releases and the other guy/gal reels in the line.....we fly thermals all day then land in a field we can buddy tow out of again the next morning.
The device has stayed charged up via the filament running through the tow line. It has been charging constantly while it was deployed during that mornings repeated step tows until conditions became strong.
Okay.....its all science fiction right now.....so were submarines.....until 20,000 leagues under the sea was written.....as a crazy idea.
Then, some inventor or engineer read the crazy idea and thought...uh...hmmm....I think that can actually be done....and viola....we have submarines....If this idea is physically possible it WILL become a reality at some point by someone, somewhere.

[Bill Cummings]

With four thousand and ninety one flights, the majority being tow flights, I see the biggest hurdle to spiral towing a weight shift hang glider as being a lock-out.

Could a gyroscopic hoop somehow mounted and surrounding each glider off set the increasing tendency to lock out due to increased line tension? (Weight concerns with a gyro.)

The greater the line tension the narrower the "Sweet Spot." A narrower workable angle left or right of the towing direction with more line tension.