WHO IS DOING WHAT WITH WALKALONG AVIATION?
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Having spoken to several people responsible for wonderful innovations in air surfing (aka walkalong gliding) I cannot believe my good fortune to be witnessing the birth of a new science activity (and sport?) that anyone can participate in. So I have elected myself to write up some notes lest these great stories be lost.
Dr. Tyler MacCready
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Tyler MacCready appeared on a PBS Scientific American Frontiers program that mostly paid tribute to his late father Dr. Paul MacCready who is also the father of human-powered aviation and a huge inspiration to anyone aspires to creative engineering. In the segment about walkalong gliding the son Tyler uses his head--and I mean that literally--and his hands to keep his invention aloft. Viewing that amazing program was my first exposure to surfing with air and it blew me away. Dr. Tyler MacCready educates the program's host Alan Alda a bit about how it works as well as speaking a little about its early development. I have not been able to contact Tyler (e-mailed via Aerovironment, not reply--anybody have contact information?) and ask about some of the early forms he worked with, but even if I never do, the PBS/Scientific American piece is a great introduction.
I did, however, feel somewhat tormented because the program did not tell you where to get one of those things until I crossed paths with...
Phil Rossoni
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| I...um...liberated this picture of Phil from his site. Great visual representation of the air wave created with the paddle as you move it forward! |
Phil Rossoni has a wonderful, rambling web site with interesting nooks and crannies waiting to be discovered. The home page is http://www.geocities.com/x_surfer2004/ and you can see great, insightful pictures and links to other great pictures here. And one of those links has an amazing video of hang gliders (the upper video) catching updrafts from a ridge so they can stay in the air--which is closely related to walkalong gliding. Also Phil's giant glider (lower).
My brother had said something about Phil flying deceased moths or butterflies and I thought I might have misunderstood. But, lo, it's for real. At the suggestion of an insect curator--Bob Greene--at the Museum of Science, Phil pioneered yet another branch. of walkalong gliding. He taps into the waste streams of live butterfly displays and exhibits. He has an elaborate process for establishing the right position even when rigor mortis has set in and strengthens them with nail polish. And to the annoyance of some etymologists he can fly the moths and butterflies upside down. Don't overlook the link to his Instructables page where he really goes into the details. http://geocities.com/walkalongbutterfly/ And here are some well set up experiments about how the lightness or heaviness (mass) of tumblewings affects flight speed
Phil thinks a lot about gliding. He referred me to this National Geographic slide show about animals which do not actually fly, but do glide. Also wingsuit skydiving. And Phil was the one who told me about the availability of the commercial "windsurfer"--3 for $10 plus $5 shipping--which might be the one Tyler MacCready patented. http://www.windrider.com.hk/products/product.cfm?id=8
Phil Rossoni's e-mail is walkalongaviation"at"yahoo.com replace the "at" with @ (I've heard it stops spambots).
Michael Thompson
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| Michael Thompson with propeller jagwing on the attack! | Plankwings were the earliest design. | Michael said that the pale things in the box are tumblewings made of condenser paper (used in capacitors and indoor plane models) which is even lighter than tissue paper. Flight speeds around 1 mph. |
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| A large jagwing complete with spinning propellers. | A large plankwing with a tethered small glider in tow, seen actually flying in the next picture. | One glider towing another. Amazing! |
The tumblewing design on Phil's web site was my entry point into actively flying. It was a marvel of design. It was simple--every fold and every part had a purpose. Its docile flight pattern makes it perfect for learning to fly. I asked Phil for the contact information for the the originator, the "flyingwingbat" (is there a story here?) aka Michael Thompson. As of this writing he is a Mechanical Engineering junior at University of Wisconsin.
In corresponding with Michael Thompson about how he developed the tumblewing, it was interesting to see how he tapped into various different influences over the years, mixed in some serendipity and hunches and came up with the tumblewing. It was a process, a series of steps. He cited origami designs like this paper helicopter and he was familiar with fanwing technology. He saw a discovery TV piece in which someone was air surfing a paper glider (he thinks it was "Beyond Tomorrow"--does anyone know who it was?) and he was fascinated. Years later when he was a senior in high school he started with walkalong gliding in earnest.
From here I'll just let Michael tell the story from his e-mail of November 2007. Note that LE is leading (front) edge, TE is trailing (back) edge, and I think AR is aspect ratio--the ratio of width to length: "While making plank wings for walkalong gliders out of thin hotwire-cut foam, I noticed that they sometimes spun (on their long axis) when I dropped them, which put them in a steep but steady and slow descent. However, they often slipped sideways to the ground after a couple of seconds. I tried bending the ends up to provide some lateral area to minimize the side-slipping and maintain steady flight. This worked nicely most of the time, but the spinning suffered slightly due to the slightly lopsided rotation. To counter that, I figured that "cupping" the LE and TE would assist rotation, sort of like the cups on a wind gauge. It worked pretty well; they rotated much better."
"If it flies, slope it" I figured, so I tried these things out with a board underneath to provide sustained "propulsion". The steep descent meant that I had to hold the board near vertical to maintain adequate airflow, and the tumblewings flew very, very close to the board, but they flew! I laughed at the whole idea, it simply amazed me that a free piece of foam could fly like that, at speeds far slower than ANY of my regular walkalong gliders. They proved to be VERY sensitive to turbulence, though. I messed around with different aspect ratios and sizes to see what spun the nicest; high AR tumblewings spun nicely, but side slipped easily due to their small endplates in relation to their overall area and weight.
"Fast forward to July-August 05, I eventually mastered flying the tumblewings in slope lift by then, but they were hard to fold from foam without cracking or springing back flatter than intended, and the foam itself sometimes had uneven density. Lateral balance is EXTREMELY important in tumblewings, lest they tilt and sideslip to the ground. I often had to add bits of tape to one side to even out the weight imbalances on the foam t-wings."
"On a wild hunch, I tried making a small t-wing out of tissue paper, since it was light and easy to work with and appeared to be very consistent. I figured that tissue wouldn't work too great due to its flimsiness (hence the small test size), but...it worked. It worked far better than ANY of the foam tumblewings. The LE and TE folds provided adequate bending stiffness (much to my surprise), and the consistent density meant side slipping was much rarer. I settled on AR's between 4:1 and 5:1 (before folding) as the best compromise. The less-porous, smooth, thin tissue meant the the t-wings spun faster than equivalent foam t-wings, increasing their stability. Win-win-win all the way around, and the design has hardly changed since then."
Michael is still tweaking tumblewings. In January 2008 he tried bending one tip up and one tip down. Doing so...:"moves the center of gravity closer to the main lifting surface, so the t-wing rotates more smoothly. This trick is very handy for large or lightweight tumblewings (most prone to stop spinning). It's made all my condenser paper (1/2 the weight of tissue) tumblewings fly much nicer. An added bonus is that you can make lower aspect ratio t-wings, down to 3:1 (before folding)." You can see more about Michael's latest innovation here http://www.geocities.com/x_surfer2004/ModifiedTumblewing1jpeg.JPG
Michael also designed jagwings for air surfing. They are a little more finicky to get working, but when you get it, they have an extraordinary glide ratio--unlike any paper airplane I've ever seen. Still, the jag wings move faster that tumblewings so they're not so good for starting out. They give you sort of a deje vu feeling if you have ever flown a flight simulator and set the view to spotting behind the plane. This is my flight with a jagwing using instructions from Michael's page of Phil's web sitehttp://www.geocities.com/x_surfer2004/jagwing.html.
Michael's e-mail is flyingwingbat1"at"yahoo.com replace "at" with @ (I've heard it stops spambots)
David Aronstein (check out this video from one of their events)! http://youtube.com/watch?v=QwRyNZE4YKE
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| David Aronstein executing a "free turn" with an F-16 Scorpion at one of his races. | David's son Jesse flying a "mini club racer." |
Michael put me in touch with yet another innovator, David Aronstein, an engineer in the Advanced Design Dept. ar Hawker Beachcraft in Witchita, Kansas. He has done several interesting things. First, walkalong gliding has blossomed as the sport it could be under David's leadership with an ad-hoc group in Wichita.
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At one time, everybody was making essentially "flying wings"--all wing and no tail section. David figured out how to make more conventional-looking airplanes air surf as well. I'll let him tell the story:
"I first heard about them from a fellow-modeler around 1990. At that time I built two stick-and-tissue flying wings, very similar to the “Red Flying Wing”) but without the decorative profile body or winglets."
"I also tried flying a conventional freeflight indoor hand-launch glider and discovered that the tail gets very much more upflow than the wing, seriously disrupting the trim [ (most free flight models have very long tail moment arm – that’s considered a good thing for freeflight stability, not so good for board flying!). I realized – as the McCreadys did – that a flying wing would be preferable; but I also had a nagging suspicion that a tailed airplane could work if it were designed properly. That would mean a small, short-coupled horizontal tail with plenty of negative incidence angle, and a much more forward center of gravity . than I am accustomed to.
"I did not act on that suspicion until ~2003, however, when my kids started getting old enough to enjoy “air surfing”. A few more flying wings, then our first “tailed” glider which was the F-89 Scorpion semi-scale jet fighter with profile balsa fuselage, stick-and-tissue wing & tail. Performance was outstanding; it is still one our nicest-flying gliders. 
Kids enjoy them, and we always take a few to any Indoor contests we go to (where the principal activity is rubber-powered endurance flying).
David Aronstein's e-mail is david_aronstein"at"hawkerbeechcraft.com replace the "at" with @ (it stops spambots I hear)
David also related that he knows of two other people who developed air surfing. Bill Watson, a freeflight modeler in Southern California who may have passed away, and Prof. Ilan Kroo at
Contact me (Slater Harrison)
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