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By red
Roadrunner71 wrote:
Sat Apr 14, 2018 10:50 pm
I have wondered for a very long Time why Hang-Glider designers have never designed a FLEX - WING that was both a Topless design, and also a Bottomless Wing? I presume that the main objection to a Fully Cantilevered Flex wing would be weight. How about it? does anyone have the answer that I am seeking?
Think about it: A Flex - Wing Sans rigging that need to be moved through the Air.

Is this your glider? 8)

It is cantilevered, it has struts, no top wires, no crossbar, and a single surface sail. It was intended to be the next generation of Albatross, the ASG-23. The "super-noseplate" and struts carried all the flying loads nicely. The cost of the "super-noseplate" prevented production.


By Lazypilot
In contemplating the design of a glider to build for myself I think that cantilever is the way to go.

A wire braced structure will give the best strength to weight ratio, but since I will launch with most of the glider's weight supported by a wheel I don't mind if it is heavier than current gliders.

I don't mind making multiple trips from the truck to the set-up or breakdown area, so having the glider in 3 or 4 pieces is Ok with me.

I'm lazy and don't want to make any more parts than necessary. So I'm thinking the glider will have a fuselage, a fin/rudder, and a horizontal tail/elevator, and a right and left wing. Even being old and worn out I should be able to carry these components by myself.

I should note here that my glider won't be a hang glider. I want a comfy seat and aerodynamic controls. And the wings won't be swept. If I feel like it I'll make it look like a Spitfire or Mustang, or maybe something else entirely.
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By red
Lazypilot wrote:
Sat Apr 21, 2018 3:52 am
I should note here that my glider won't be a hang glider. I want a comfy seat and aerodynamic controls. And the wings won't be swept. If I feel like it I'll make it look like a Spitfire or Mustang, or maybe something else entirely.

If this design is to be an ultralight glider under (USA) FAA FAR Part 103, there is a maximum stall speed limit.


It would not be easy to stay within the limits, using any high-speed design as a starting point. Something like a scaled-up Carbon Dragon may be possible, especially with a small motor to allow more weight.
By Lazypilot
Red---Goober sez Hey!

I understand the maximum stall to be 27mph.

The PSS, or "power scale slope" Rc gliders aren't true scale, they have more wing and tail area. I was doodling some sketches of what I think would be a easily built glider, and just for kicks I sketched a low wing design. I drew a side view and to get the approximate sizes I put my feet up to the nose, and drew me in a reclined position, a comfy one where my feet are lower than my butt.
I sketched a sliding canopy that could be used in cold weather, and then based on the distance from my feet to my head I made the aft fuselage about 150% of that length.
So for fun I added a belly scoop, and there was a Mustang! So then I got to looking at the PSS models and realized that by scaling one up to man size I'd have a glider, a basic shape that has been around for a long time, with no experimental aerodynamics. I've always thought that the free-flight models, with their good stability and nice large horizontal tails, when scaled up would make for a potentially decent ultralight glider.
I just want to build a glider that is like the type of aircraft I flew before Hg---You know, Cherokees and C-150's and Champs, etc. I had full 100% control of those aircraft's attitude at all times, something lacking in the Hg world that I always resented and have come to loathe. Yes it's simple and convenient to use, but there comes a time when one has to move on.
Set up and breakdown time isn't really very important to me. Having to make several trips from the truck or trailer to the set-up and breakdown area is no sweat either, in fact by having it in several pieces I won't have to carry a heavy weight.
I was sorta/kinda kidding about the Spitfire/Mustang idea, but I don't see why a glider dressed up to look like something cool would be any harder to build, and if the wing and tail areas and the moments are reasonably conservative it should be safe enough. What the heck, in 1977 I flew a swept aft flying wing called a "Zipper" that had no luff lines or washout struts and I had no parachute. Them was the days, alright. It's possible but unlikely that I'll be in any more danger in my Mustang than I was in that uncertifiable hang glider.
I'm wanting to K.I.S.S. so might try a "pitcheron" design, that way no linkages to the tail, just a lever for each wing, that would control each wing independently, with a means of coupling them in pitch so I could fly with one hand for roll. A big trim tab could be used to set the trim AoA where I want it. The tail would be set to keep the fuselage attitude in line with the relative airflow. I think that George Spratt's designs were similar to this. The idea being to have as few parts as possible, and to make it as easy to fly as possible.
When I first started having serious thoughts about this project I was "stuck in the box" and wasted time and thought on how to make it fold up. Then I realised that this thing is just for me, the hang glider pilots already have what they want, so I only need to make it breakdown far enough that I can get it from home to launch and LZ to home.
That simplifies things. I can make the wings from Styrofoam, "Swiss Cheese" style with aluminum tube spars embedded in them. The fuselage would have four longerons and foam shear panels, with the aft fuselage not requiring as much tubing, gotta get more clear on that. The four longerons will give me a lot more protection than I now have hanging in my Sensor.
I got a lot of inspiration from that guy that made a electric powered biplane on YouTube. He helped me realise that it's little more than an oversize model plane, and while considerably more dangerous than flying a model, if engineering is consulted and vehicle testing shows it's strong enough, and reasonably stable, then---Why not?
The old cliche "It ain't rocket science" applies here. It's nothing really any different than a 1930's light plane, or a 1980's Skypup. It's little more than a streamlined version of what Spratt did so long ago.
As long as I continue my therapy by writing about it I'll continue to make progress. Just how successful I am in the end is important, I don't wanna get hurt, but the Journey is the real prize. As Otto used to say, designing a glider is one thing, building a glider is one thing, but to fly a glider--well, that's a whole 'nuther thing. But each of those is a worthwhile hobby in itself. So even if I never soar in it, I will have had a great trip.
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