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#406111
Frank, have you ever flown the Pacific Windcraft Eclipse? It had many of the characteristics you were looking for. It was designed by Jean-Michel Bernasconi and Bob England, and was one of the best low-speed "scratching" gliders I've ever flown ... light handling and a stubborn resistance to stalling, even if provoked. Its main drawback was a lack of glide at speed and a low top speed, but these wouldn't be factors in the glider you're envisioning.

Last time I talked to Bob before he died, he said he was working on the design for a beginner glider much like the one you describe. Maybe there's somebody in the SoCal flying community that can find out what happened to that design, and how far he might have gotten with it.








#406116
Thanks, that's interesting information. I probably never saw these designs since I quit flying hang gliders in 1979 but I have always read the HG magazine "religiously" over all the years since then.

It would be good to know what he was working on when he died. One of the reasons that I'm describing my design thoughts here as a open source project is so that all is known and could be picked up by someone if I kick the bucket (I'm almost 84 so it has to be considered). I've said before that I have zero interest in making any money from this, if I manage to build one it will be the only one and anybody is welcome to pick up the ball and run with it ( I would like credit for any ideas of mine used).

< Its main drawback was a lack of glide at speed and a low top speed, but these wouldn't be factors in the glider you're envisioning.>

My HGBT design will also have both of those drawbacks. Nobody would ever set a cross country record with my basic trainer.

Red's suggestion of the name "Puffin" for this glider I like and I'm now referring to it as the Puffin.

BTW - Something I should have mentioned in my recap of the thoughts behind this is, that all through aviation history people have begun training in low aspect ratio, larger wing area (light loading), craft. There is a reason, those usually make for a docil, easy to fly, slower more forgiving aircraft. Exactly why the Puffin is low aspect ratio with large area.

Frank
#406190
The late d--- Boone (of Progressive Aircraft fame) applied for a patent of a design feature that would lower the stall speed of a hang glider. I wonder if his idea might be applicable to your basic trainer design?

See:
http://www.patentsencyclopedia.com/app/20130299627

Excerpt:
Patent application title: Low speed, high performance hang glider
Inventors: Richard Boone (Wichita, KS, US)
Publication date: 2013-11-14
Patent application number: 20130299627

Abstract:
Sail deflection, from large resultant moments, creates excess aerodynamic twist and limits hang glider performance. Incorporating a rear spar and sail attachment system, as a design feature, allows control and definition of this critical performance component. Hang gliders with this design feature will produce more total lift which in turn will produce lower stall speeds and less drag.

Claims:
1. Replacing the conventional "Cross Bar" with a "Rear Spar" and Sail Attachment System, per this claim, provides an effective method to control performance limiting aerodynamic twist on hang gliders.

2. Lower aerodynamic twist, created by the incorporation of a rear spar and rear spar sail attachment, increases the potential for lift, which in turn lowers the stall speed.

3. Lower aerodynamic twist, created by the incorporation of a rear spar and rear spar sail attachment, reduces drag which, for any effective lift, increases glider performance.

<snip>
[0012] This combination of low speed and high performance is suitable to training operations and allow training to be performed at lower risks and at vastly more locations. With help from a support staff, a glider per this claim can be used to train pilots of limited physical ability including small children and individual restricted to wheel chairs.
#406196
Thanks for the information. It's an interesting concept, I don't know about the spar loads and the attachments to the sail and spar out toward the tips.

Since my spar goes to the tips and is farther back than conventional HG's spars I could play around with some sort of attachments to the sail battens out there. Also, my truncated tips help support the rear of the sail more than conventional HG.

Richard's comments about the need for slower, easier to fly, trainers is right along the line of my thinking on this subject.

I didn't know Richard personally but I've known of him for many years. I'm sorry to learn that he has passed. :(

Frank C.
#406200
PocoPete wrote:
Sat Jan 12, 2019 4:10 pm
The late d--- Boone (of Progressive Aircraft fame) applied for a patent of a design feature that would lower the stall speed of a hang glider. I wonder if his idea might be applicable to your basic trainer design?
See:
http://www.patentsencyclopedia.com/app/20130299627
Abstract: Sail deflection, from large resultant moments, creates excess aerodynamic twist and limits hang glider performance. Incorporating a rear spar and sail attachment system, as a design feature, allows control and definition of this critical performance component. Hang gliders with this design feature will produce more total lift which in turn will produce lower stall speeds and less drag.
Claims: 1. Replacing the conventional "Cross Bar" with a "Rear Spar" and Sail Attachment System, per this claim, provides an effective method to control performance limiting aerodynamic twist on hang gliders.
Campers,

I can understand how excessive twist (washout) is a limit on performance, but limiting that twist may or may not be helpful to beginners. You may indeed get better performance, but maybe at the expense of the forgiving stall characteristics which help a beginner. Seems to me, sprogs with upward limiters could do the same thing, for less weight than the new rear spar and cabling.

Being a long-time Fledgling pilot, it almost seems that this new design is a re-imagining of the "Fledgling A" model (the original Fledgling). I'd expect very similar performance, certainly, but you may need spoilers (or other aerodynamic controls) to steer it. I greatly favor the use of such aerodynamic controls, on all HGs. You could do worse than to fly with power steering and power brakes; trust an old Fledgling pilot, here. When you have solid roll authority and retractable dive brakes, the small LZs are much easier to deal with.

I'm all in favor of new designs with HGs, and I would really like to see Mr. Boone's ideas being constructed and well- tested. I would not want anybody to think I am being critical here, when maybe I just need more information. If anybody has more information or actual pictures of this new design, please post them.
#406219
Progress update.

As of midnight last night I finished the design of my nose and tip plates. It was a little more effort on my autoCAD than just designing a nose plate because the tips have a different folding situation and I wanted to make all six pieces identical, for my labor efficiency when it comes time to fabricate them. With these plates the glider will be able to be folded with the six foot tip tubes in place. The diagonal brace for the tip will need to be removed or at least disconnected at one end, minimum.

Next design effort will be all the hole positions on all the airframe tubing (I've already done the portions that go between the plates).

Red, I agree with your comments regarding the sail billow out toward the tips which Richard was attempting to eliminate. I regard that billow as an advantage in a training glider, even though it subtracts from the glide performance. And it certainly helps with weight shift roll control an important factor in someone learning to fly. You mention tip stalls also and my permanently twisted tip will also help with making the tip portion the last to stall.

Frank C.
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