A dumb question.

joe nelson

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Where do you attach the tow line? Would it be where an engine thrust line would be or does it matter?
 

C. Beaty

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The line of action of the towline should pass through the machine’s CG. That is the reason Bensen designed an elevated tow boom rather than simply attaching the towline to the keel.
 

Doug Riley

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What Chuck says is true. In practice, of course, the towline pulled down on the nose more and more as the gyro rose up into the air. Flying at a towline angle of 20-30 deg. was normal.

At that angle, part of the "thrust" force on the line was really the weight of the tow car. To balance things out, the rotor thrustline ended up well ahead of the gyro's CG; the rotor was lifting a fraction of the weight of the car. If the towline were released under tension, the gyro would execute a wild flare in response to the unbalanced nose-up rotor thrust. If you wanted to release, the correct technique was to dive until the line slacked, then cut loose.

Yet another good reason not to use a light motorcycle as a tow vehicle.
 

joe nelson

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Chuck and Doug,

Thank you for your input! Is there a specific length for a tow rope...it would seem that the longer the rope the more controllable the glider would be. Can you fly only in straight lines behind the tow vehicle or can you continue to fly upwind?

I was amazed at Chris's account of flying on the wind. That sounds like fun to me and worth looking into as my next project!
 

Doug Riley

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Here in the Northeast, small-airport runways are typically about 2500 ft. long. I flew with ropes as short as 30 ft. and as long as 150 ft. Some people around here went to 200. There's a practical limit, as, with a long enough rope, the car will run out of runway before the gyro is even off the ground.

A long rope is much more fun, though.

You can do some pretty radical excursions to each side of center. The nose will still point at the car, however, resulting a pretty radical side-skid. You don't want to land in this attitude. The resulting rollover can be quite violent.

Ken Brock aero-towed his gyroglider with a FW plane (like a conventional sailplane) and released at 1000 ft. or more. Of course, a gyroglider isn't likely to do much soaring; Ken's flight was more of a sled-ride.
 

joe nelson

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The rope question was to see if the tow line was like the scope when towing a boat. A short line makes the boat being towed pretty squirrelly.

What would be some charactistics of a good glider/trainer? Would you need a prerotater for faster spin-ups?
 

Doug Riley

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I don't recall the 30-foot rope making the gyro "squirrelly." There's no tendency for a gyroglider to fishtail or do other uncommanded things that we associate with unstable trailers or boat-towing operations -- unless perhaps you get a resonance going with a stretchy nylon line. You're better off using some other rope material.

A Bensen-style putt-putt prerotator would be handy to keep the blades going as you turn around at the end of the runway (or back-taxi downwind if there's a breeze). As the gyro pilot and car driver become an experienced team, though, they get better and better at turning around quickly.

With my single-place glider, I got into the habit of turning it around by just planting my feet, lifting the front of the keel and walking it around. Took about 3 seconds.

Ron Menzie, my instructor, turned around his 2-place by doing a 3-point turn, backing up with the nosewheel hard over by pushing back with one foot on the ground.
 

joe nelson

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Doug,

I'm looking for another project after my tandem R/C gyro. I want to get my grandkids involved in flying and a glider sounds like an inexpensive way to do that. My two grandsons are always with me in my shop wanting to get involve in anything that I'm doing. It would be an absolute blast to teach them to fly a gyro.

Does anyone fly something like a Parsons trainer as a glider? This is the configuration that I would like to have for my first gyro glider.
 

Doug Riley

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A Parsons is a stretched Bensen with an extra mast. I don't see why it couldn't be towed as a tandem gyroglider; it even retained the tow boom up front.

I don't know of anyone who currently sells kits for the Parsons.

The Bensen side-by-side gyroglider would be much easier to reproduce. The changes from the classic 1-place Bensen are limited to the foot bar, seat and rotor cheek plates.
 

Chris Burgess

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Winds over 22mph and a steel cable. Takes some skill to get the rotor spun up but once that's done, it's all "green" flying after that. Don't climb very high if there is any chance the wind will quickly die.
 

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Arnie Madsen

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Chris Burgess - that is a cool photo. I have heard of it being done but have never seen a good picture of it. thanks.
Now I am like Joe , I am surprised at where the cable attaches (looks high) but I thought it through and it starts to make sense .

Joe Nelson An old Orthodox Catholic Priest strapped me in his tow gyro and away we went. I am not a Catholic, but I recall praying while he was pre-spinning the rotor by hand. I think the rope was about 100 feet long and I said I wish it was longer (for altitude) behind the tow car. He said he calculated it as long as he dared , yet to still be able to see the hand signals between the car and the Bensen.

After a few flights I also recall wishing the grass strip was 10 miles long. Great thread Joe, love the questions and answers. thanks.
 

Doug Riley

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There was an old gyro pilot named Father Svoboda (?) up in Canada once upon a time. Was he your "flying parson?"

Igor Bensen was a Russian Orthodox clergyman, too.
 

joe nelson

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Thanks for everyone's input!

Scott, my son-in-law really likes the aquaplane so I think he will end up building that one. He says it looks like a good babysitter,lol. He's also a plumber.

Doug, I'll look up some old Benson plans and go from there. As a glider, what is the instrument requirement if any? Next question is; How do you size the rotor length?

Chris, do you have a picture of your cable attachment on you glider that you can post? Would a standard FW glider attachment be usable for this application? Please, forgive me I'm just trying to get a mental plan for this project.

Arnie, thank you for your kind input. You always respond to my dumb questions with great understanding. My grand sons are hopefully the next gyro generation and find the love for flying as I did 43 years ago:)
 
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Doug Riley

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Joe, the standard Bensen glider had a plastic Dwyer wind meter for an ASI. A Hall Bros. unit would work just as well and be easier to mount. The stock Bensen also had a little flag intended as a "drift indicator." I never had one and see no need for it in towed flight. The gyro always points toward the car.

Rotor diameter is not very critical. The standard Bensen 22-ft. metal rotor worked for both one- and two-place gliders. The Bensen wood blades were a foot or two shorter, and they worked fine, too. A 2-place gyroglider, flown 2-up, weighs about the same as a light 1-place powered gyro. The towing thrust available from a car is nearly unlimited because tires on the ground, and transmission gears, are so much more efficient than a prop. Gyrogliders were ordinarily flown at airspeeds that would be way behind the power curve on a powered machine -- look at Chris kiting at 22 mph!

The Bensen kits included a standard sailplane tow hook (expensive!). It mounted on a swivel block at the end of the tow boom so it could "gimbal" in both axes. A string was run back to the seat to allow the pilot to trip the release.
 

joe nelson

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Doug, that's spot on! You've answered most of my questions that I was thinking about. Hopefully, I can get started this coming Monday with gathering the tubing. You have been extremely helpful...thanks so much.
 

joe nelson

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I have just returned from spending the weekend at Ft. Campbell, Ky. While there I saw several very interesting aircraft. At the Pratt Museum, there was two aircraft of note. The first was a CH-47A Chinook that I checked out every nook and cranny. Surprizingly, the skid plates for the rear ramp are wooden...who'd thunk it. The next helicopter was the AH-56A Cheyenne. It was much larger that the Cobra it was sitting beside. The Lockheed rotor system was certainly different as was the tail rotor and propeller combination.
 

Arnie Madsen

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There was an old gyro pilot named Father Svoboda (?) up in Canada once upon a time. Was he your "flying parson?"

Igor Bensen was a Russian Orthodox clergyman, too.
That was the one Doug. His name was "Father Svoboda" If I spelled his name wrong it will not be the first time. I am not Catholic and was not religious at the time but I recall praying that the pilot was religious and we would have a safe flight.

I figured that was a good idea because I was sitting in the seat beside him.

I think that is the first time I had a prayer answered . It was around 1977. I am still alive and still typing. I also recall encouraging him to go up 4 more times. He did , and then he folded his hand. He tried to explain how hard it was to pre-rotate by hand for 4 flights in a row on a short grass strip. He also mentioned he was 70..

I find it also interesting that Igor Sikorsky was a Russian Orthodox Christian who spent his spare time praying his helicopter would fly and also did a treatise on the Lords Prayer. I made up the part about Igor Sikorsky praying his helicopter would fly , We all know he leaned heavily on years of engineering knowledge and years of failed experiments before he got off the ground. The treatise on The Lords Prayer is factual.. After all , they say helicopter pilots only tell true stories. I figure that includes gyro pilots as well.

You would be proud of me Doug. For 60 days I sailed my schooner every day to my car in the morning , and every day back to my doorstep at night. My schooner is an 8 ft. long lapstrake dinghy with a 35#thrust electric motor and two deep cycle batteries , and never once did my big toe get wet. Local floods have made me think I am a Pirate or something.

I have dry feet , it allows me to type this without getting electrocuted , I love having a whole day go by without getting electrocuted.

Now that I know Igor Bensen was a Russian Orthodox clergyman too ..... well I think it is time to hoist the Pirate flag, grab a beer , and state the fact that successful Russian aviators are way too religious.

Not to mention my life depends on them from time to time.

Some day Doug , I kind of think I would like you to tour me along your dock to show me a real schooner, I would enjoy that very much. I will probably decline your invitation to go sailing , guys like me last a long time by never getting a big toe wet.

But if you ever get to be 70 and pre-rotating a tow Bensen , , I request at least 4 flights. thanks. I hope your intellect is as good as ever Doug , and you can sort out the humor in my comments. thank you for all the interesting pirate stories you tell trying to be an aviator or something.

I pray the all your prayers are answered.

Arnie.
 

joe nelson

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Would a four piont landing gear work better to prevent rollovers for a trainer?
 

Doug Riley

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Four-point suspensions are much more stable for any wheeled vehicle than 3-pointers. I imagine they're not used more on aircraft because the steering (or coordinating) mechanism for two wheels in front involves extra linkages (weight), and because two, spread-out front wheels add drag up front.

For gyro training, the Bensen-style rigid-boom gyroglider with linked, castering mains is simpler.
 
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