All things hang gliding. This is the main forum. New users, introduce yourself.

Moderators: sg, mods

User avatar
By red
#406309
TjW wrote: Tue Jan 22, 2019 9:41 pm
USHPA7 wrote: Sun Jan 20, 2019 11:02 amBack then everybody was saying that nobody would want to fly a 75 lb hang glider (that was the estimated weight of my Skysail). Ha - time proved them wrong.
Frank.
Later on, I took grief for have to stuff six battens per side on my Fledge.
TjW,

Same here, from the same pilots who now stuff 21 ribs into their glider, without a second thought. :lol:
#406310
<< "Later on, I took grief for have to stuff six battens per side on my Fledge".>>

I think the simplicity and lightness of the "standard" Rogallo tended to delay progress on more complicated but better flying and safer gliders.

While I was struggling learning to fly my 75 lb Skysail, which had to be transported in two halves, in a trailer and took a lot of assembly time, my teenage son Matt was flying his 30 lb Eipper 17' Rogallo off mountains all over SoCal. He often went with the Bob Wills group to fly new sites.

Frank
#406317
USHPA7 wrote: Wed Jan 23, 2019 1:23 am I think the simplicity and lightness of the "standard" Rogallo tended to delay progress on more complicated but better flying and safer gliders.
That may be true, but it also created a larger market to accommodate those pilots who eventually wanted "more complicated but better flying and safer gliders."

That's often the way technology proceeds, by making inferior products that many, many people bought, thereby creating a demand for superior products. I don't think Apple would have created the iPod without Sony's already having released the Walkman, proving that there was a market for portable music devices. Who uses a Walkman anymore? Who even owns one?

Similarly, those of us who have been around computers may still remember using cassette tapes to store programs and data. They made it possible for the home computer user to store their stuff, and without them the home computer would have stayed a hobbyist's plaything rather than a useful tool. Although the cassettes did the job, they were in many ways a major PITA. When the floppy disk came along, people abandoned the cassette format, only to abandon the floppy disk when thumb drives came along. But if those first computers had no method at all for conveniently storing data, the personal computer industry would have been dead in the water, with no market for floppies or thumb drives.

At least, that's my take on it.
#406320
Yes.

That is why I designed and I am building the "Hang Gliding Basic Trainer", Puffin. To get that entry level glider back in the hands of beginners. Sure it's not as simple as the Rogallo ( 10 battens to slide in) but hopefully will be as easy to handle and fly better and then the student moves on to better performing gliders.

My premise: many aircraft pilots learned to fly in a lower aspect ratio, easy handling, slower flying airplane, than they currently fly. Why not HG pilots?

New flip phones are again available (I use one).

Frank
User avatar
By mario
#406327
Frank, your new trainer glider reminds me of the glider Paul MacCready was designing and making when I first started hanging out with his family in 1974. I was just 11 years old and they were working on what Paul called the “MacCready Safety Glider”. It was basically a Rogallo wing that had the crossbar extending out to the tips to create truncated tips and it had shaped ribs along the wing. His youngest son was the test pilot on the dune and he discovered on the first flight that the stiff wing had reverse roll control and crashed it. Luckily he wasn’t hurt too badly and they scrappped the glider. That wing fortunately became the source for my sailing canoe with jib (which worked great) and unfortunately ended young Marshall’s desire to ever fly again. We went on to designing many wings after that, and made our models with control frames and movable dangling weights to simulate a pilot’s input. Making those models with my brothers and the MacCreadys, going to the dunes to ground skim all day, watching poeple like Volmer Jensen, Taras, Chris Wills and many others fly, and seeing people like you and other designers coming out with a new design every week were the best years of my life.
Here’s an article you may remember: https://www.nytimes.com/1973/09/01/arch ... t-sky.html
It kinda predicts paragliders in the end of the article.
Good luck with your project!
Mario Miralles
#406330
Thanks Mario.

I had not seen that article. It brought back a lot of memories. Kind of sad to realize that the popularity of the new sport didn't grow like we thought it would. Now we only have two manufactures left in the US. :( And hang gliding is illegal anywhere in the city of Torrance. I remember people sitting out on their patios of the houses on the cliff top enjoying watching the gliders float past. I'm glad that, thanks to Joe Greblo, we still have Dockweiler Beach even though it doesn't have the high cliff of Torrance Beach.

I was not aware of the MacCready safety glider experiment. I wonder how similar to mine it was?

My Puffin's keel pocket and floating cross spar may cure the adverse yaw problem he had with his design.

I always enjoyed talking with Paul every chance I got. One time he brought me his son's Colver vario to repair because it had been in the salt water off Point Fermin when his son landed in the surf.

Frank
#406334
mario wrote: Thu Jan 24, 2019 1:00 am It was basically a Rogallo wing that had the crossbar extending out to the tips to create truncated tips

That rang a bell for me. Back in the 70s, Chandelle came out with the "Competition" glider, and one of its design features was a crossbar that attached toward the aft end of the leading edges. I think the idea was to reduce deflection at the rear of the spar. At any rate, the glider quickly earned a reputation for "adverse flight characteristics" and was at least part of the company's ultimate demise. Maybe there's somebody on the board who can give more details than this.

I remember having a Chandelle Comp come into my shop in Maryland, where we "de-Comped" it, shortening the crossbar and fitting it at a more conventional point along the leading edge ... converting it, in essence, back to the "standard Rogallo" configuration. Although it flew well enough after the conversion, the owner still wasn't happy with it and ended up buying a Cirrus 3 from us.
User avatar
By USHPA7
#406335
The dangerous aspect of the Comp was lack of reflex. Once the nose went down to a critical low angle it would go into a divergent, non-recoverable dive. The lack of stabilizing reflex gave the glider a better glide than other rogallos.

My son Matt, witnessed a death at Box Springs Mountain in SoCal. The Comp pilot said to anyone standing nearby: "Here I go in my "killer Comp"" just as he started his launch run. People had started calling the glider that name by then and he was mocking them (reminds me of the attitude toward PG's near the ground collapse nowadays).

Away from the mountain he went into the dive and I don't know what caused the nose to drop in the first place, possibly turbulence, but the dive became divergent and he went straight in.

Matt quit flying hang gliders then, after being on the scene of the accident.

Frank C.
User avatar
By TjW
#406336
jlatorre wrote: Thu Jan 24, 2019 12:20 pm
mario wrote: Thu Jan 24, 2019 1:00 am It was basically a Rogallo wing that had the crossbar extending out to the tips to create truncated tips

That rang a bell for me. Back in the 70s, Chandelle came out with the "Competition" glider, and one of its design features was a crossbar that attached toward the aft end of the leading edges. I think the idea was to reduce deflection at the rear of the spar. At any rate, the glider quickly earned a reputation for "adverse flight characteristics" and was at least part of the company's ultimate demise. Maybe there's somebody on the board who can give more details than this.
As I understood it, there was a pitch stability issue. Under load, the forward/inboard part of the leading edge bowed in, and the outboard/rear part flexed out, giving more camber in the front and less washout.
A couple of them dove in. Whether this was specific to the Comp, or just the same luffing dive problem that all standards had would be hard for me to say.
I always thought the folding crossbar was cool. It made for a remarkably quick setup if you left the control bar set up, as was the style at the time. Pull up the kingpost and fasten the wire, spread the leading edges and fasten the the center of the crossbar with, I think, a pip pin.
User avatar
By red
#406339
jlatorre wrote: Thu Jan 24, 2019 12:20 pm
mario wrote: Thu Jan 24, 2019 1:00 am It was basically a Rogallo wing that had the crossbar extending out to the tips to create truncated tips
That rang a bell for me. Back in the 70s, Chandelle came out with the "Competition" glider, and one of its design features was a crossbar that attached toward the aft end of the leading edges. I think the idea was to reduce deflection at the rear of the spar. At any rate, the glider quickly earned a reputation for "adverse flight characteristics" and was at least part of the company's ultimate demise. Maybe there's somebody on the board who can give more details than this.
Campers,

I remember the Chandelle Comp glider. What follows is all to the best of my memory, and the teachings of pilots I trusted . . . The leading edges were 18,' and the crossbars attached at 15' from the nose. Those skinny leading edges would flex upward in slow flight, creating a Cylindrical sail. (In theory, the glider would "fit" in flight on two large parallel cylinders, that had some overlap between the cylinders.) The Cylindrical variant of the Rogallo wing did fly better, but did not handle very well. It did also fly slower than a Standard Rogallo. That much is the good news.

The bad news was that if the Chandelle Comp glider ever stalled or went weightless, the leading edges became straight again. The glider then became a fully stalled Standard Rogallo, and the nose dropped into a dive. Now there was little or no lift (so, no Cylindrical, and no airfoil shape to the sail), but only drag. With the drag on the sail, the leading edges then bowed inward at the nose, not upward, which caused the wingtips to pivot outward. That pivot action pulled the trailing edge down flatter, creating a "down elevator" all across the wingspan. That "down elevator" caused the glider to dive steeper, faster, and steeper, until stopped by the ground. Weight shift by the pilot would have no effect on the dive. Luff lines (which were almost completely unknown, and not in common use then) might have caused the glider to recover from the dive. A modern HG parachute (which did not exist then, either) would have saved the day, if the glider was high enough to use one. We seldom flew high enough to use a parachute, in those days.

It was not long after that time when the Pitch-Testing truck was developed, and now all HGs are REQUIRED to pass the truck testing.

NONE of these problems would apply to Frank's new Puffin design, because the Puffin will have large and strong leading edge tubes, fixed ribs (so the airfoil can NOT collapse in a stall), and (ANTI-) luff lines, so the trailing edge can NOT get pulled downward even if the frame flexed at all.

We did pay a high price for the aerodynamics lessons 'way back when, but we have learned.
#407037
Somewhere on this forum I described my experiments with the Lake Sail Feather design. I just looked for it so i could reference it here but I couldn't find it. So here it is again.

I was flying an Eipper FlexiFloater ("standard Rogallo") and concerned about full luff dives. John Lake and I were often flying at the same sites when he came up with the Sail Feather product, so I decided I would run some tests on its ability to pull a Rogallo out of a full luff dive.

I built a 1/4 scale model Rogallo and weighted the control bar base tube with sufficient weight to trim for a normal glide. I had a second story window that had a straight wall down to the ground of my back yard. I started launching the glider with increasingly lower angles. Until it reached a critical angle it would pull up into a glide across the yard. At some point the low angle would cause the sail to begin to luff and the glider would nose over into a straight down dive. Of course there was no "pilot" weight shift effort to counteract this dive tendency but I'm convinced that such efforts would not have helped in very low angle launches.

Then I attached my scale version of John's "Sail Feather" to the rear bottom support cables (strings). To my amazement, not only could I drop the glider at very low angles and it would pull up into a normal glide attitude but I could even drop it inverted and it would recover to level flight just before contacting the ground. Think about that, folks! The model could be launched beyond vertical and still have a positive recovery.

I also noted that with this positive upward rotating force I needed to move the CG a little forward to get a smooth glide from one that was porpoising from gentle stalls. On my full scale Eipper I had to move my weight trim a little forward to retrim the glider after i started flying with the SF. However, i also found launching was easier in that holding the nose angle at the right position during launch wasn't as critical because the tendency to tuck, if it was a little too low, was gone. Any of us who flew standards in those days can remember slamming into the hill during launch if we pulled the nose down a little to low. I was a "happy camper" when I found that tendency was gone after I started flying with the Sail Feather.

These tests convinced me that i wanted to fly with a Sail Feather on my Rogallo. I wouldn't fly one any higher than I cared to fall today, without a version of Lake's Sail Feather. I was too cheap to pay John $5 for a Sail Feather, so I made my own. I still have the Rogallo with my copycat Sail Feather, I sure wish now that it was one of John's. :oops:

At the HG reunion meet, at Dockweiler, in Sept 2000 Paul MacCready spotted the copycat Sail Feather on my Eipper and commented to me that he considered that to be the most important change ever made to the Rogallo type design. I wish John Lake had been there to hear that.

Whether it is the downward force on the Sail Feather or the drag above and behind the CG that initiates the rotation of the glider's nose upward I can't say for sure. I always thought it was the downward force on the SF but it could be the latter or a combination of both forces working together toward the same reaction on the glider.

Frank Colver
#407039
USHPA7 wrote: Sat Apr 27, 2019 1:44 pm

At the HG reunion meet, at Dockweiler, in Sept 2000 Paul MacCready spotted the copycat Sail Feather on my Eipper and commented to me that he considered that to be the most important change ever made to the Rogallo type design. I wish John Lake had been there to hear that.

With all due respect for Paul's astonishing contributions to our sport, I would have to say that even more important were methods of limiting washout range, such as Charlie Baughman's washout tubes, and the use of "luff lines" which could be retrofit to existing batten (and later rib) designs. (The name of the person who came up with the latter escapes me at the moment.)

But the Sail Feather could be seen as an important first step toward the solution to the problem in the classic Rogallo/Dickenson wing. If the evolution of the hang glider hadn't gone to higher aspect ratios and extensive means of sail bracing, I think that the Sail Feather would have become a fixture on every glider.
#407040
In 1973, Terry Sweeney added a strut under the sail near each wingtip, with a cable to the top of the king post that limited the strut’s downward arc about its attachment to the leading edge. In an extreme dive, it acted as an up-elevator. It was a combined dive strut and reflex bridle, as we would understand it today.

See Flying squad, my short history of the east coast U.S. hang glider manufacturer Sky Sports, including photos and info from Chris Gonzales and Robert W Cordier.
#407055
In the October 1976 Ground Skimmer, Manta announced a 'floating interior truncated tip.' It acted much like the dive struts inside the double surface of many of today's flexwings. The Manta example, however, was an S-curved (cambered and reflexed) batten near the tip. Unlike the other battens, it had a hinge attachment to the leading edge tube, with a limit on its downward travel. (Manta's use of the word truncated seems wrong to me in this context.) The development was said to be led by one Jim Davis.
#407056
The Ken Russell movie Tommy, filmed in 1974, featured Roger Daltry of rock band The Who apparently launching from a castle tower near Portsmouth, England, in an all-white Birdman standard Rogallo. He flew shirtless and helmet-less while singing a long-forgotten song, thus causing dozens of mods and rockers on the streets below, some wearing World War 2 German steel helmets, to stop fighting and instead break out into spontaneous gyrations while they looked up at him in awe.

TOMMY (1975) Sensation [1080 HD] clip on TouTube
User avatar
By TjW
#407059
Conveniently, the control bar changes completely when he's being carried.

This must have been a common design feature in the 70s, since there was a Hawaii 5-0 that had a Wills Wing style control bar in the long shots, and an Eipper style in the closeups.
User avatar
By USHPA7
#407062
Speaking of Eipper control bars...........

Last summer I constructed a new aluminum rowing frame for my solo "cat" whitewater boat. In one place i needed a sturdy cross bar and conveniently found the right material in the tubing stock in my shop. It was a purple anodized Eipper base tube (which was actually 3/4, sch 40, aluminum water pipe). It sat there for about 40 years and now I had found a use for it.

Fast forward to last September. I met with Dave Cronk, in Bluff Utah, for some paddling / rowing on the San Juan river. He instantly recognized the purple tubing in my boat's rowing frame as being from an Eipper control bar! 8)

Frank Colver
#407083
The "Sweeney Stick" batten around 1973-74 probably was the first "defined tip" or "interior truncation," but did not see use in production designs. Dave Cronk separately suggested the idea to other designers at the 1976 Nationals, sharing what he already had on his drawing board. And Manta was apparently the first to put the idea into production with its Mirage.
-- Bill Allen in his Flying Bull column (on the yellow inside back cover) in Hang Gliding, August 1977.

Incidentally, I think Bill Allen might be the hang gliding photographer W.A. Allen, but I am not certain.
User avatar
By USHPA7
#407089
Yes.Hang gliding photographer, Bill Allen, did sign W.A. Allen. But if there was another Bill Allen, I don't know.

Frank C.