How to design a new wing (apols if OT)

[Genghis the Engineer]

Most of the world uses microlight definitions that include Vso<=35kCAS, that is clearly a very important design driver and tends to deliver low speed aircraft. The newest designs are achieving 80-90kCAS in level flight, which impresses microlight pilots, but in real terms is still very low speed.

And being low speed, form drag is a bit less problematic than it would on a higher speed aeroplane - but clearly not trivial, and all the cables and cantilevers create very draggy airframes. Billy did a great job with the PulsR but it's still, well, a flexwing!

There have been attempts to achieve much lower drag with a similar wingform in, say, the Dyke Delta or Verhees Delta. But they are using much more conventional structures, and don't use aeroelastic deformation to achieve stability in the way a Rogallo wing does.

G

[Downwind Lander]

Don't get me wrong, G, the wing is an incredible achievement - incorporating all control surfaces in one mathematically horrifically complex 3D shape. What i am saying is that it isn't efficient and this could be improved on ... somehow.

[Genghis the Engineer]

As a generator of low speed lift, or as a generator of lift for low structural mass, it's extremely efficient. Ditto achieving a functional wing for very few parts.

If I understand you correctly - you basically want to reduce profile drag? That means the short of exercise Bill Brooks did when he created the PulsR, *or* incorporate the basic wing structure into a conventionally controlled aeroplane - a bit like the Verhees Delta?

If you can do that, and retain the foldability for transport and storage of a current Rogallo wing, you might do something quite worthwhile.

G

[Downwind Lander]

Originally Posted by Genghis the Engineer

As a generator of low speed lift, or as a generator of lift for low structural mass, it's extremely efficient. Ditto achieving a functional wing for very few parts.

If I understand you correctly - you basically want to reduce profile drag? That means the short of exercise Bill Brooks did when he created the PulsR, *or* incorporate the basic wing structure into a conventionally controlled aeroplane - a bit like the Verhees Delta?

If you can do that, and retain the foldability for transport and storage of a current Rogallo wing, you might do something quite worthwhile.

G

Let me put it this way.

If you compare the power requirements and the cruising speeds of Rogallo wing a/c and the Long EZ, there is a big discrepancy.

If you take a good look at these two, it seems obvious why - but because it "seems obvious", it doesn't follow that the conclusion is correct.

Protecting myself with the Edward Debono "Po" concept, here is a Po suggestion: rip the wings off a EZ and nail them on a microlight - quickly glossing over the fact that there are control surface issues, with a few tweaks, how much better/worse would it do?

[Genghis the Engineer]

Run the numbers, let us know

My guess is, not as well if you leave all the struts and fittings in place. Both are designs optimised to the wing they have. But I'd be the first to read with rapt interest your proof that I'm wrong.

G

[Downwind Lander]

Originally Posted by PDR1

1. The microlight would never get fast enough to use the longeze wing at its efficient operating point,

2. and would have a much higher stalling speed than is permitted for microlights.

1. That's the thing - could it happen? maybe Yes, maybe No. At the moment, No, but - see below -

2. Yes, this is so and also there is a wing loading problem to solve, possibly both with a larger wing area.

[Downwind Lander]

Originally Posted by PDR1

One of my prized possessions is a copy of "Aerodynamic Drag" by Dr. Sighard Hoerner

Do you mean "Fluid Dynamic Drag" or is that a completely different book?

[cavuman1]

Francis Rogallo

My father, who was the Executive Vice President of Aetna Life and Casualty, a/k/a "Mother Aetna", was a friend of Frank Rogallo. Though Dad was a Mechanical Engineer (Georgia Tech) and a Masters of Marine Architect (U.S. Naval Academy Annapolis), he was fascinated by and loved every aspect of flight. The Aetna insured the U.S. Space Program from Mercury through Apollo, and when the Gemini Program was first on the drawing board, the Rogallo "Parawing" was considered as a recovery system. Dad (and the astronauts!) were entirely in favor of the concept: a steerable vehicle with a glide ratio would preclude the danger-ridden parachute landing in the ocean. Unfortunately, the engineers could not find a weight-economic way to stow the wing during launch and orbit. Deployment on orbit prior to re-entry presented its own set of problems.

On Christmas Day 1964 I was presented with a real Rogallo-winged kite powered by an .049 engine. The trailing edge of the device, which spanned about four feet, was autographed by Mr. Rogallo and his wife, Gertrude. My father, younger brother, and I took this high-viz orange-winged beauty to a nearby elementary school's playground for a test flight. The engine started on the first try and we released the kite into a calm, severe clear azure sky. Up, up, up she went, ascending in a slow left-handed turn toward heaven. The engine's fuel tank was relatively large; the Rogallo was but a speck (~ 3,000 feet?) when, as soon as the engine was fuel-exhausted, a straight ahead course became evident. She flew for miles and miles and out of sight on an eastward course - I like to think she made England...

Fast forward to 2004. My wife was the Assistant Curator of the Outer Banks History Center in Manteo, North Carolina on Roanoke Island. (You know, the first British attempt at colonization of North America. Virginia Dare, etc.) She had archived maps and notes dating back to 1583! I was visiting one spring day when she said "Come back into (the temperature, light, and humidity controlled vault, occupying about 10,000 square feet) my parlor, she smiled and beckoned. I have something I know you will like!" Thinking I might have lucked into a little "afternoon delight", I was not disappointed. Before me lay the entire compendium of notes and drawings of Francis Rogallo. He lived in Southern Shores, North Carolina, next door to a big sand dune in a place called Kitty Hawk, where he would often fly his own man-carrying designs. He had come home to test the same winds that his heroes, the Brothers Wright, had spent the Fall and Winter of 1903 mastering powered, sustained, and controlled flight.

My wife and I lived across Roanoke Sound, a mile from the tall and imposing Wright Brothers Memorial. It features a very bright rotating beacon that cycles around every eight seconds. It serves as a warning to sailors of the treacherous coast of North Carolina and a beckoning candle to aviators. It stands where our species first took flight. My wife learned to fly there. She would return from a flying lesson, give me a hug and a kiss, and say "I just flew in the same airspace as Orv and Will!" Our Golden Retriever would join the hug with his cold nose and wagging feathered tail. He was nearly the color of my Rogallo that had flown out of sight all those years ago...

- Ed

[JOE-FBS]

Excellent story, thank you very much.


On a light-hearted note, as both a Yorkshireman and an engineer involved with buoyant flight, I might change "our species first took flight" to "our species first took powered, sustained, controlled flight". (For the avoidance of doubt, I put the Wright brothers on the highest of pedestals for that achievement and the science that they performed to reach it.)

[cavuman1]

Dear JOE-FBS,

Your suggestions are correct, accurate, and appreciated! I have edited my story incorporating them. Thank you as well, my friend; I am glad you enjoyed my story.

- Ed

[Downwind Lander]

Originally Posted by PDR1

It's the first edition of the same book. The original edition is called "aerodynamic drag", and the subsequent editions were called "fluid-dynamic drag".

(wiki refers)

PDR

Very interesting PD. I see that the author was treated to an extended American working holiday under Operation Paperclip, presumably in 1946, when he wrote your book which he self published in 1951. Then the other one comes out fifteen years later.

I wonder if material was removed between the volumes on the grounds of military secrecy. A comparison of your book, which must be pretty valuable, to the available Fluid Dynamics could be intriguing.

[Genghis the Engineer]

cavuman - thank you, that is really interesting.

May I ask something: I've flown a few Rogallo winged aircraft, and studied them fairly extensively. What I have often wondered about is the relationship between Francis and Gertrude. To what extent where they a true working team of two engineers, and to what extent was Francis in the lead and Gertrude essentially his assistant?

History tends to assume the latter, but I've always rather believed the former. If you were around people who knew them, I'd be really interested in your views.

G

[cavuman1]

The Rogallos

You are most welcome, Genghis! I wish I could tell you more about Francis and Gertrude, but I never met either one in person. I can tell you that the original patent for the Rogallo Wing was taken in both of their names and that many of the drawings and diagrams which I sifted through were executed and signed by Gertrude. I remain under the impression that although Francis wore the pants in the family, Gertrude was a co-equal partner, contributor, and inventress.

The largest paragliding area on the largest natural sand dune on the East coast of the United States is Jockey's Ridge State Park in Kitty Hawk, North Carolina. I am told that Mr. Rogallo flew his designs there with some frequency until age caught up with him. I booked hang gliding lessons there on three separate occasions; two were cancelled for high winds and one for lightning. Now age and osteoarthritis have caught up with me - I don't believe my "undercarriage" is up for the punishment of takeoff and landing! I am jealous of you and your experience in that type of craft. I have a number of soaring hours, in craft ranging from Blanik LET L-13's to Grob 103's. I love it and wonder if hang gliding puts one even closer to being "one with the air"?

If you are interested in further research, you may contact The Outer Banks History Center at: https://archives.ncdcr.gov/researche...history-center. Kitty Hawk Kites, a most excellent purveyor of everything from fancy kites (build the "Ghost Clipper; I did and it takes two to handle her in a strong breeze) to hang gliding lessons. Please see: Kites - Hang Gliding Lessons - Kiteboarding Lessons - Kayak Tours | Kitty Hawk Kites.

I look forward to hearing of your adventures, Genghis! May I take this opportunity to wish you and yours a Very Merry Christmas, clear skies, and soft winds...

- Ed