.

[sg]

This sport is full of ENTRY BARRIERS.

Anything that lowers entry barriers, IS A GREAT IDEA.

Entry barriers need to be systematically addressed across the sport of hanggliding at every level possible.

[Windlord]

So true!

[USHPA7]

I've got some people at Dockweiler Beach chomping at the bit to be test pilots on the Puffin. Probably better if this 83 year old HG pilot lets them do a couple of launches first. My life would be complete if I saw one of the pilots who soar Condor 330's on tht 25 foot bluff, soaring the bluff in the Puffin.

Actually the young, experienced, pilots there will be needed while making the CG trim adjustments. They can pick themselves up off the sand easier than I can.

However, I know experimental designs don't work out as expected sometimes. Most of the many RC gliders I've designed and built (most of the RC gliders I have flown since 1962 have been my own, one off, originals) flew very well. Ah, but then there were the "dogs". let's hope I don't have to change the name from Puffin to Fido.

Frank

[Takeo77]

I gotta tell you, esp after today, a Condor 330 is an awful choice to start a small stature pilot on. Less span, less intertia, and a smaller control frame option would go a long way towards making life easier for people who are not built like Michael Jordan

[Paul H]

I would think that the small Alpha would be a much better choice over the Condor for a height and reach challenged student. Its smaller control frame with less mass and span to deal with should be easier for a newbie to deal with.

[USHPA7]

Or a smaller Puffin. they could be built in different sizes. I just happen to weigh 237 lbs so i'm going to build a big one.

I would love for someone else to step up to the plate and say they are going to build one of any size. This is an open source project, I hold no monetary claim over the design concepts (but I would like credit).

Any one out there who wants a winter project? i will release all of the AutoCAD drawings that I have made, just ask. This is one for the betterment of hang gliding, not one for Mr F. Colver.

[LoneEagle]

USHPA7
I'm interested in building and flying HG. I came across plans for rogallo wings on the internet but there are no plans online for modern hg designs. I'm interested in building a modern glider. If you have plans for a modern wing design, I'd like to have them for study purpose.
AJ

[red]

USHPA7
I'm interested in building and flying HG. I came across plans for rogallo wings on the internet but there are no plans online for modern hg designs. I'm interested in building a modern glider. If you have plans for a modern wing design, I'd like to have them for study purpose.
AJ

AJ,

The Rogallo could barely fly (compared to the new HGs), and there were fatal design flaws which killed a lot of pilots back then. You don't want to go there. Good used HGs can cost far less than the materials needed for a plans-built Rogallo.

The only proven, decent plans-built ultralight gliders that I know are the ULF-1, Mitchell Wings, and the Sandlin GOATs. There may be some others, but I have not seen them fly, or you need to be a horse jockey as pilot, or they use exotic materials not friendly or cheap for the DIY crew.

These three listed are all FAA 103 ultralights; no licenses, and no inspections are needed, just like HGs. I would class the Mitchell Wing as "expert HG pilots only" and even that would require modifications which are not on the original plans. The other two have tail planes. ULF-1 plans produce a wood and fabric glider; they cost ~US$200. GOAT plans produce a modern aluminum and fabric glider; they are free downloads. Expect to spend ~US$4K (+/-) on materials, and hundreds of hours on construction for each. See my web page, linked below, to get flying cheaper and sooner.

http://m-sandlin.info

http://m-sandlin.info/technicaldrawings/td.htm

[USHPA7]

Thank you Red for giving him some good advice.

I do not encourage anyone, without a lot of experience, to use my basic trainer design ideas as a homebuilt project, because it is completely experimental.

That said, I would love for one of the two hang glider manufacturers in the US to take up the task and build one. Either one of them has the experience and ability to properly carry out this experimental project from start to completion of flight testing. I was hoping Wills Wing would be interested in doing at least some of it, since they are 15 minutes from my place. They have indicated that they are too busy to participate in this project, other than selling materials to me. I am grateful for that assistance.

I am also pleased that WW is busy building gliders these days. That's good news for our sport.

Frank

Here's a photo of the underside of the covered 1/5 scale model, before flight testing was done.

Covered model underside.JPG (206.59 KiB) Viewed 1642 times

[TjW]

Is there a reason why the crossbar runs all the way to the tip?

Bending loads out there are relatively small. A shorter crossbar would weigh less and be less likely to fail by buckling.

[USHPA7]

Yes, it is to support the loads of the highly truncated tips. Also remember it is not as long as it would be if it was positioned the same way on a standard glider because the span is shorter. The diagonal brace from the center of the tips will help support the LE some (not on model, see drawing photo).

I recognize that the LE bending loads are inward across the full length of the tubing which is different than other HG's. But the tubes are only 15 1/2 feet long which helps. I'm still deciding on LE tube diameter and I'm going to do some load testing after I buy the 7075 tubing from Wills.

Thank you for your input, I welcome any ideas and suggestions. At this point in time I'm probably fairly well set on this design as I want to start building soon. But I envision that after the 1st glider, there will be "upgrades" in design and construction based on problem areas as discovered. Even if I never build a 2'nd one, I will publicly identify the problems that I see as needing to be corrected. One problem could very well turn out to be structural strength, which is why this prototype will see a lot of Dockweiler Beach sand. So many homebuilts and new designs saw their first flights there that will I feel honored to add to the list. This year the test flights of my new swing seat harness saw 1'st air there and back in '72 my "Colver Skysail" rigid wing.

ONWARD WITH THE DOCKWEILER TRADITION!

Frank

[DMarley]

So, this design is pure weight-shift for roll control. It appears as though there is absolutely no geometry change as compared to a typical hang glider (floating cross-bar). I'll guesstimate that this will create a positive feedback loop of sorts in most conditions, making roll control more difficult to manage.
Typical hang gliders have roll control primarily with geometry change rather than pure weight-shift. If the cross-bar did not float, there could not be geometry change in the sail, and roll control would be very hard to initialize with weight displacement, but also would be nearly impossible to correct for external rolling forces in an expedient manner.
Because of the shorter span, pure weight-shift may initiate roll more quickly, but still you will have the problem of correcting for external rolling forces.
I hope you have remote means of testing your design for roll control.

[DMarley]

I tried to edit that last post because it sounded a bit negative after re-reading it, but I was too late.
Anyway, I'm sure the glider will go through a typical design spiral after testing and retesting, and little problems will pop up and be corrected.
It would be interesting to test a remotely-controlled version with control frame and rigging and suspended weight. I still believe that there should be some provision for wing warping of some sort for predictable roll control so that control input will closely mirror the behaviors of typical wings.

[red]

When I started flying HGs, my Rogallo had a one-piece crossbar bolted solidly to the keel, and no keel pocket. It turned just fine, with no moving parts.

When I flew the Albatros ASG-21, with a keel pocket, an ordinary weight-shift movement caused the glider to turn in the opposite direction (adverse yaw).

[USHPA7]

DMarley,

I realize it doesn't show in the drawing, or is incorporated on the model, but the design has both a floating cross spar and a deep keel pocket. So, it should turn just fine with weight shift. I do appreciate your concern since you couldn't have known about the floating cross spar and deep sail pocket, since I haven't talked about actual mechanical details of the glider.

One of the things I have been giving some thought to is how to support the reflex at the "swallow tail" and still allow the sail to shift side to side. I'm thinking of a vertical short post that supports the sail batten TE upward but can pivot side to side. I think tying it up to the rear kingpost cable would limit its side to side movement too much since the cable would be very close at that point.

The cross spar will probably use a Wills ball joint and typical haul back cable. A problem I'm facing is that the cross spar will be behind the king post and will have to pass it when folding. A suggestion I was given, and I think may be the solution, is to detach the bottom of the post, when folding the glider, instead of merely folding it down.

I think the fact that the floating cross spar goes all the way to the tips may actually enhance the effect of weight shift on the sail billow.

Lots of mechanical details to be worked out as the project progresses.

Frank

BTW - Red, the standard Rogallos did have a fixed cross spar and no sail pocket, as you say, but the LE bending at the tips allowed the sail to billow more on the side the weight was shifted to. It was our observation of this billow change that led us to realize why flex wings would turn so well with weight shift and rigid wings would not. Later on, some started adding a cable that ran from tip to tip around the nose so that the billow increasing side would pull the other side tighter. The Wills SST went to this system after the early units didn't turn well. I modified my early SST ( WW's #1) to this system and it greatly improved turning response. Kudos to the person who first realized that the cross spar didn't need to be attached to the keel!

[red]

Red,
the standard Rogallos did have a fixed cross spar and no sail pocket, as you say, but the LE bending at the tips allowed the sail to billow more on the side the weight was shifted to. It was our observation of this billow change that led us to realize why flex wings would turn so well with weight shift and rigid wings would not.

Frank,

I'm not surprised that you knew this. Not everybody does.

Even the Comets relied on this same flexibility there, with their keel pockets and floating crossbars. A friend of mine once broke both Comet leading edge spars behind the crossbar bolts (long story, but no injuries). He could not obtain the correct .049" wall tubing, unless he spent enough money to buy the real factory parts. Instead, he home-made the replacement rear spars from common .058" wall tubing. (It's gonna be stronger than stock now!) We convinced him (not easily) to test the repairs on the bunny hill. He found out the glider was totally non-steerable, with the thicker tubing. He couldn't fly it, and would not sell it. With no more money available, he shelved the glider. A bunch of the local pilots here chipped in to buy him a pair of new factory spars, and all was well again.

What people don't know that they don't know, can be hazardous to health. I believe that you are the guy who can get it right, there.

[red]

Frank,

It was great to hear from you again. I agree with your choices of alloy and tubing size for the Puffin design. Training gliders can catch a lot of flak in HG lessons, so any improvement in ruggedness can certainly be worth the very slight increase of weight. In my experience as an HG instructor, no HG student pilot has ever questioned the mass of their trainer glider; they simply trusted our decisions, there.

Your deliberate and thoughtful approach to hang glider design is appreciated here. You are welcome to send me sketches of the various structures and junctions needed by your proposed Puffin. It occurs to me, across four decades of building and repairing everybody's gliders, I now have a fair assortment of such hardware pieces. They may not be exactly what you what you might envision, but these parts will certainly be adequate to the task, in each case. I can think of no better use for my spare pieces than to help with the construction of your unique prototype glider. There will be no need to return any unused parts to me, of course. Lead on, good sir!

[jlatorre]

Great write-up, Frank! Do keep us posted.

My own experience in training gliders was the "Trainer" which was produced jointly by Sky Sports and Electra Flyer. When I moved to California, Kitty Hawk Kites West (later named Western Hang Gliders) was using them but, when the sails needed replacing, we at Pacific Windcraft came up with an improved sail design that offered a slower speed and enhanced roll authority using the existing fixed cross-bar frame. They bought those sails from us until I left the company, and I presume that the patterns were shipped to Airwave's English factory after they closed down Pacific Airwave.

I also remember seeing the Flight Designs Javelin being used as a trainer, along with the La Mouette Atlas, since both were designed as lightweight single-surface "floaters."

[DHMead]

Frank,

Remember that since this won't be a certified glider, the king post need not be stressed for significant negative G's. Also, the UP Mosquito had a king post that was raked forward a lot (like 45 degrees) so maybe you could get away from your folding problem that way.

[USHPA7]

Raked forward, great suggestion, I had not thought of that and will consider it.

Thanks,
Frank

A recap on the concept for any newcomers who have not read this thread from the first post.

Many pilots learned to fly, often self taught, in the early days of this sport on a "standard Rogallo". It was easy to ground handle, easy to fly and land standing up, often with no steps and light weight carrying back up the training hill. However, a little tricky to launch with a more critical angle than modern single surface flex wing gliders ( a little too high and you didn't get off and a little too low and you got pounded into the hill). The glide angle was poor, so steep training hills were required which made launch goofs more damaging to pilot and glider. Then in flying high there was the full luff dive chance and steep banked turns were not very good.

My "brainstorm" occured when I thought: how about a design which has all the good points of the Rogollo but with better launch characteristics and safe flight characteristics. A glider that was easy to ground handle (short span), light weight (hopefully under 40 lbs), a better glide than Rogallo (shallower hills, more small hill air time), slow launch, flight & landing (large area, high lift airfoil), good roll response, good pitch damping (not"twitchy" on pitch control), soft stall, etc. Basically a glider so easy to launch, fly, and land that the beginner gets that great first flight feel that builds enthusiasm to keep coming back and strive for that day when he or she moves on to a general utility glider and the higher launches - the fledgling has left.

There is also the potential that this could be a fun glider for "dune grooming", working narrow, close in lift, on coastal dunes and small inland ridges. Definitely it's a special purpose, uncertified, glider just for training but it could have several other "niches" it fulfills in the right hands.