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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.
#406254
Construction has begun with the fabrication of the nose and tip plates (6 pieces in all). The nose plate is larger than most nose plates because I wanted all of the plates to be identical and tip plates have to be larger to accommodate the tips folding along side the spar.

I've sent an order to Wills Wing for the 7075 tubing and the particular Condor 330 battens I need.

Still need a sail designer / maker.

Frank
#406272
Here's a photo of the actual beginning of fabrication of this glider. Drilling what will become nose and tip plates.

The finished total weight, for the six identical pieces, came out at 2.5lbs which kind of bummed me since I'm shooting for a complete glider weight of under 40 lbs. I thought of adding some lightening holes but then I decided to wait until I see how the tip plates behave under the stress of holding the tip twist under negative loads. I can always reduce the weight of any "over designed" parts, after the glider has been tested.

Frank Colver
Puffin fab begins, nose & tip plates.JPG
Puffin fab begins, nose & tip plates.JPG (311.29 KiB) Viewed 1388 times
Completed six plates.jpg
Completed six plates.jpg (184.09 KiB) Viewed 1386 times
#406510
Progress report.

I've been buying hardware for the glider's construction. Tubing end plugs, saddle washers, aircraft bolts, nuts, flat washers. The saddle washers were for 42mm tubing but a lot of my tubes will be 50mm. However, the washers were economic in a 50 pcs bulk package. So, I rigged up a holding jig for enlarging the washer's curve to match 50mm tubing using a 2" hole saw - it worked beautifully! 8)

Since I will be assembling and disassembling the glider sections many times during the development period I will use cheap hardware store wing nuts, on the AN bolts, until final assembly with AN lock nuts. So don't panic if I post photos during that time showing wing nuts. :shock:

At the present time I'm waiting for Wills Wing to notify me that the materials I ordered from them (tubing & battens) are ready for pickup.

How I'm going to get the sail designed and made is still up in the air but I've been learning some things about how to design it using my AutoCAD drawings and my scale model, thanks to Steve P at WW.

Stay tuned, folks, :popcorn:
Frank C.
#406513
I'm a little surprised that WW is selling you tubing and battens for anything other than repair of one of their birds. Have you been working closely with Steve on this project?
#406514
USHPA7 wrote:
Thu Feb 14, 2019 4:19 pm
Progress report.
I've been buying hardware for the glider's construction. Tubing end plugs, saddle washers, aircraft bolts, nuts, flat washers.
Frank C.
Frank,

"Nuts & Bolts" is a separate heading in the Yellow Pages phone book, far better than "hardware" or some such. The real Internet Yellow Pages IS the Yellow Pages tab at:

http://www.anywho.com

Enter the Nuts & Bolts heading in the "Business Name or Category " line, and give them a local ZIP code for your location. You can SORT the list by Distance. All other Internet "yellow pages" are just wannabees.

AN-4 bolts are 28 Threads Per Inch (1/4"-28). An-5 bolts are 24 Threads Per Inch (5/16"-24). Call around first, for these special wingnuts. The AN spec wingnuts would be AN-450 (1/4") and AN-550 (5/16") but nobody will have them. Just ask for 1/4"-28 wingnuts, or 5/16"-24 wingnuts. Those thread numbers may also be called National Fine (NF) thread, in each size.

Prolly more than you wanted to know :lol: , and a NICE aircraft "AN bolt chart" linked as a free .PDF download, can be found on one of my special web pages:

http://user.xmission.com/~red/AN%20Bolts%20Decoded.htm

Happy hunting!
:mrgreen:
#406521
Thanks red. I have all that stuff pretty well under control. I've been buying AN bolts, nuts, washers, etc., for many years and the plastic parts, end plugs & saddle washers, I found a good inexpensive source in London. They got here in about 5 days.

The difference for the AN hardware is that now instead of a 50 mile round trip to Aircraft Spruce, in Corona CA, I just get on the web and order from them. Shipping is less than the gas I would use to drive to their store. Plus, I don't get there and find they are out of stock on one of the AN bolts I need.

Because the wing nuts are temporary I'm not going to use the very expensive aircraft wing nuts, just hardware store stuff. However, I'll probably need to do a web search to find them in 1/4-28 thread. The local Home Depot most likely will only have 1/4-20.

mario: I sent you a PM about the WW parts.

Frank
#406592
Gathering more glider parts toward this project.

Dan, at Susquehanna Flight Park, in NY has offered a salvage Falcon 1 195 but I took a "rain check" on his generous offer because of the long distance shipping. THANK YOU DAN!!!

Mario, here in SoCal, offered a salvage Wills Eagle 180 frame minus control bar and king post. I picked that up today from Mario, along with some great hang gliding conversation. THANK YOU MARIO!!!

The Eagle frame provides some good WW special parts which I needed.

So, now, I just need a WW control triangle bar assembly and king post preferably from a Falcon or Alpha from one of the larger models. Looking for round tube type, not faired.

Project still waiting for tubing and batten ribs from Wills wing because the aluminum mill that supplies them is running behind.

Flew the 1/5 scale free flight model at dockweiler again last Monday.

Another thought on roll control: If the floating keel and deep keel pocket still don't allow enough differential sail deformation with weight shift, how's this idea? I add a spring section to the diagonal braces that hold the 6' tip tubes out against the sail tension. This spring would be similar to a small shock absorber but without the oil damping. With the right amount of spring compression force, when weight is shifted to one side the spring compresses, in effect shortening the brace, allowing that tip to rotate inward and slacken the sail. The amount of movement would be proportional to the amount of weight added to that side's sail, due to the pilot's weight shift. An "ace in the hole" idea in case the glider doesn't roll well enough. The spring assembly would add more weight to the tips and more rotational mass so better off if I don't need to do this.

Frank Colver
#406593
USHPA7 wrote:
Sat Feb 23, 2019 11:55 pm
Another thought on roll control: If the floating keel and deep keel pocket still don't allow enough differential sail deformation with weight shift, how's this idea? I add a spring section to the diagonal braces that hold the 6' tip tubes out against the sail tension. This spring would be similar to a small shock absorber but without the oil damping. With the right amount of spring compression force, when weight is shifted to one side the spring compresses, in effect shortening the brace, allowing that tip to rotate inward and slacken the sail. The amount of movement would be proportional to the amount of weight added to that side's sail, due to the pilot's weight shift. An "ace in the hole" idea in case the glider doesn't roll well enough. The spring assembly would add more weight to the tips and more rotational mass so better off if I don't need to do this.
Frank Colver
Frank,

I believe that the tip tube (to the trailing edge) of the Puffin will provide the flex required there for easy handling. Maybe a smaller, lighter tube would provide that advantage for you if needed, while reducing the weight out there. Still, always good to have some options in the design.
#406599
Frank,
In regards to the kingpost and crossbar positions, you have the options of raking forward the kingpost (as someone already mentioned) and not having your crosstubes pulled back to the point of a straight line. Both of these things have been done on most modern gliders for years.
It was great to see you yesterday and I hope the parts are useful.
Mario
#406605
Thanks Mario.

Here's a jpeg copy of my January 22 drawing which does show the angle of of the cross spar with the middle slightly forward and the kingpost mount is behind it. I the king post can still be straight up in this position and be OK or it could be slanted forward a little.

Of course any offset between the kingpost attachment point and the control bar attachment point does put a bending load on the portion of the keel between those two spots, when a hard negative load is experienced like a wheel or control bar landing. However, many gliders have this arrangement and when I look back at my Skysail I'm amazed that there was not an issue with that. The Skysail essentially had no keel, just a rib and support tube. The kingpost is mounted at the trailing edge and the control bar near the CG. The kingpost and control bar saw a lot of impact loads while I was learning to fly it but I never had any damage to that center rib tube, which if my memory is correct was only 1" dia.

Frank

BTW - The 44mm tubes shown are now 50mm and the keel may have to be 50mm also if Wills can't get the 42mm for me in time. the tips remain at 42mm I need them to be somewhat flexible and may switch to a different alloy and/or in a smaller size.
Basic Trainer airframe & battens inch dims.jpg
Basic Trainer airframe & battens inch dims.jpg (304.89 KiB) Viewed 820 times
Attachments
colver-skysail_id870.jpg
colver-skysail_id870.jpg (32.69 KiB) Viewed 814 times
#406702
The lightest hang glider ever IIRC was the Whitney "Porta-Wing", which used a cable for the leading edge. It packed up to 6ft, and was claimed to weigh 29 lbs. It developed a bad rep for pitch stability, but this could probably be remedied with a horizontal stabilizer called the "Sail Feather", invented by John Locke (if my memory serves correctly), back in the mid 70's. Over the years I've wanted to get my hands on a Porta-Wing & try this mod, but the one guy I know here in PA with one in his collection, won't part with it.☺

I mention this since your Puffin design already has the crossbar extending out the tip, like the Porta-Wing. My 2 cents.☺

Sincerely,

Billy in Philly, flying since '75
#406703
Thanks Billy in Philly,

The Porta Wing was the only hang glider where I felt unsafe standing directly below it as it flew overhead. It seemed like it might just drop vertically straight down on me.

The sail feather inventor / maker was John Lake. After I did some dive testing on a five foot scale model of the standard Rogallo with and without using a scaled Sail Feather, I added one to my 19' Eipper FlexiFloater.

I was dropping the model at different dive angle launches from a second story window. Without the Sail Feather the model would go into a full luff dive below a certain angle and nose straight in. With the Sail Feather I could actually launch it inverted and it would pull out before hitting the ground. That was enough to convince me! I still have the FlexiFloater with the Sail Feather. BTW - It also made it easier to launch the Rogallo.

I think the pitch stability problems with the Porta Wing were more due to the flexing of the LE under load and possibly sudden stall separation, due to the sharp (small dia) LE.

Frank C.
#406707
Hey, that Whitney Portawing was the first hangglider I ever flew! I saved up my allowance and bought myself a 'lesson', which I remember vividly. The instructions were just "Run!". No wasting words on angle of attack, stall & airspeed, etc. I doubt our instructor knew any of that stuff. I later learned that the nick-name for that glider was Whitney PortaCoffin. I kept saving and eventually bought myself a Chandelle, another glider with pitch problems. Ahh, memories. /jd
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