The Highs and Lows of Human-Powered Flight

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On March 19th 2012, YouTube user jarnosmeets80 uploaded a video to YouTube entitled "Flying like a bird | part 14/14." In it, a man donning a set of homemade wings and a helmet with a GoPro attached achieves what many wishful-thinkers, scientists and millennia of wingless bipeds have long dreamed of doing: flying. Sadly, one month later the video's creator, filmmaker Floris Kaayk, admitted the whole thing was an elaborate hoax. Skeptics will have been quick to dismiss the video straight away, and anything more than a cursory Google search might have convinced most of the same. But, with more than 7 million views at time of this writing, it's pretty clear that as a land-based species, it doesn't take much for us to suspend our disbelief at the idea of being able to fly. Even if it is just for one minute and 50 seconds.

Of course, Kaayk is far from the first to be inspired by the birds. Greek mythology's Daedalus and Icarus famously got airborne under their own steam, and set the stage for a lively cast of historical characters that flew the noble flag for science while taking to the skies - and more often than not, the ground again a little too quickly. One of these earliest known accounts comes from China. Emperor Kao Yang (circa sixth century) is believed to have taken to strapping prisoners to kites to see if they would fly as a means of entertainment, under the pretense that it was part of a Buddhist rite of liberation. Something that semi-backfired, however, when one plucky prisoner, Yuan Huang T'ou, reportedly landed safely and survived. This earned him a place in the history books as one of the earliest recorded human flights, along with the dubious privilege of a "lighter" sentence: death by starvation. Around the turn of the 10th century, Andalusian inventor Abbas Ibn Firnas was reported (by "several trustworthy writers") to have glided a "considerable" distance after making some wings, covering himself with feathers and launching from a suitable "eminence." Then there was Eilmer of Malmesbury, a Benedictine monk who, with his crude cloth wings, threw himself from a church watchtower in the 11th century, landing alive, but at the cost of two broken legs.

Not all of the early developments were quite so... hands-on though. In the 15th century, Leonardo da Vinci - famous, of course, for such artistic works as the Mona Lisa and The Last Supper - also had an interest in the physics of the natural world. Pictures of proto-ornithopters (machines that fly with flapping wings) are well-known findings from his journals. These have never been proven to be airworthy, but at the very least, they demonstrated his keen eye for the basic mechanics of nature-inspired flight.

Da Vinci's journal drawings.
Da Vinci's journal drawings.

It's not hard to imagine that with such a poor success rate, those early attempts didn't really inspire a deluge of future efforts. Some years later, though, science, and a new understanding of aerodynamics, would see the quest for human flight reinvigorated. But, as anyone who's ever been to a Birdman Rally (or more popularly of late, a Red Bull "flugtag") will attest, it hasn't stopped people from throwing themselves off of things, all for a brief taste of flight.

Up, Up and (Not) Away: The Rise of the Modern Era

If pilots ever hoped to harness any level of control over their man-powered craft, they'd need to look further than a bicycle with wings. That's possibly one reason why a revival of the ornithopter (flapping winged craft) would soon follow.

Around the beginning of the 20th century, human-powered flight took some important — and slightly less suicidal — steps forward, with the formation of the Peugeot prize. "10,000 francs which has been offered for any one [sic] who can fly a distance of ten meters in a man-powered machine" read a report in the New York Times about the event. Essentially bicycles with wings, these "man-powered machines" (known as aviettes), would descend upon Bois de Boulogne, France and attempt to take to the skies (or at least get off the ground) to secure the pot of cash. The first such competition was held in 1912, but it would be a full nine years until someone would get their hands on the money. On the morning of July 9th, 1921, champion cyclist Gabriel Poulain managed the required 10-meter distance, at one meter above the ground with his dual-winged aviette. He managed the distance a total of four times, with his longest voyage reportedly measuring in at a full 12 meters. To achieve this distance, it's estimated (albeit by Poulain himself) that he reached a speed of 40 KPH while riding the unwieldy device. Finally parted with his money, Robert Peugeot began a trend — one that we still see today — of inspiring would-be pilots with large monetary sums.

Shortly after signing Poulain's check, he announced a second prize of 200,000 francs for the "next step" (although there are few details of what this entailed, or if it ever took place). Of course, pedal power is all well and good for brief 10-meter jaunts along the French countryside, but with no means of further propulsion, these flights were bound to remain on the short side. Considering the Wright brothers' first powered flight, in 1903 was only 120 feet, by comparison, 10 meters (33 feet) might seem humble — but with only the power of the human body, and a little bit of cunning and determination, it wasn't a bad effort.

To achieve this distance, it's estimated (albeit by Poulain himself) that he reached a speed of 40 KPH while riding the unwieldy device.

In 1929, German Engineer Alexander Lippisch developed one such human-powered vehicle (they can be engine-powered also). It was launched via an elastic cord, and piloted by a young man named Hans Werner. Legend has it Werner wasn't really putting his back into the job of keeping the craft afloat, and that when Lippisch learned of this, he offered the romantic pilot a holiday to see his girlfriend if he could power the craft for the desired 300-meter distance. After which, he dutifully managed it on the very next go. There are, however, some doubts cast over the validity of this reported flight as being truly man-powered, including some suspicion that the vehicle didn't have enough wing area to perform the task. With solid evidence hard to find, and some speculation that the launch mechanism was as much responsible for the flight as the red-blooded German at the controls, Lippisch's achievement remains up for debate. He would, however, go on to put any doubts of his aerodynamic knowledge firmly to rest, by later designing the first-ever rocket-powered fighter plane — the Lippisch Ente and the Messerschmitt Me 163.

The Kremer Prize and the Flight of the Gossamers

The Gossamer Albatross' Kremer Prize-winning flight across the English Channel
The Gossamer Albatross' Kremer Prize-winning flight across the English Channel.

Following in the footsteps of Robert Peugeot, British industrialist Henry Kremer figured the best way to inspire innovation in the world of human-powered aircraft, was to appeal to the pockets of engineers. He set up a number of challenges (three of which have since been claimed) each with a financial reward reflecting their difficulty: The first to fly a figure-eight course around two markers half a mile apart, the first to fly from England to France and a world speed challenge.

It was these prizes that inspired the biggest turning point in muscle-powered flight's history, and where the work of Dr. Paul MacCready and his various teams would start a new chapter in human-powered flight. MacCready took on the first Kremer prize — for flying a figure eight — in 1977 with his Gossamer Condor craft. The final version of this vehicle, comprised of a large wing, pilot nacelle and double-skinned airfoil, was flown by cyclist and hang-glider Bryan Allen. On August 23rd of that year, Allen completed the 1.6-mile course as designated by the Royal Aeronautical Society, located at Minter field in Shafter, Calif. This flight was important for a number of reasons, but in no small part because it represented the first controlled, sustained flight complete with human-powered takeoff. A long way from the wonky bicycles of Bois de Boulogne, or haphazard pre-WWII ornithopters.

Upon awarding the £50,000 for the successfully completed figure eight, Kremer set a new challenge of crossing the English Channel.

MacCready would go on to claim a second Kremer prize with another Gossamer: the Albatross. Upon awarding the £50,000 for the successfully completed figure eight, Kremer set a new challenge of crossing the English Channel. Using their work with the Condor, MacCready's team started on a new craft. This time, they used exotic materials to lower its weight, which included the then-new technique of creating carbon fiber tubes, and Kevlar — a first for a Human Powered Aircraft (HPA). Test flights of the shorter-winged design in 1978 proved encouraging, with flights of 15 minutes being recorded on multiple occasions. Soon, after continued improvements to the design, pilot Allen managed a 13-mile, 69-minute flight over Harper Lake, Calif. The target distance of 22 miles was now within sight for MacCready's team, which brought the Albatross over to the English coast ready for the prize attempt on June 12, 1979.

The team started assembling the craft in the small hours of the morning, to much media anticipation. At around 6 AM, Allen launched from a makeshift runway, and the challenge was on. Despite their best preparations, and favorable conditions, the voyage was peppered with problems. An account on the AeroVironment website (the company MacCready went on to found) details how Allen reported, not long into the journey, that the transmit button on his radios malfunctioned, meaning he could hear his colleagues below him on the boats, but only respond with nods and gestures. Later on, due to the crossing taking longer than expected, Allen's water supply would run out leaving him dangerously dehydrated and contending with leg cramps — far from ideal when pedaling across the English Channel. Another knock-on effect of this extended journey time would see the dials and controls inside the craft lose power, leaving Allen to guess his altitude and airspeed. But, despite all this, they forged on. At one point the team came close to aborting, with turbulence starting to aggravate the already precarious situation. In a last-ditch effort to carry on, Allen lifted the Albatross higher where he found calmer winds, at least calm enough for him to endure another hour before finally landing on the beach at Cap Gris Nez victorious.

The Gossamer Albatross.
The Gossamer Albatross. (Engadget)

MacCready and his team scooped up two major Kremer prizes in as many years. This would prove to be a pivotal period for human-powered aircraft, and the Gossamer designs would be the new reference point for future projects. Prior efforts had been a mixture of trial and error and hard work mixed with a basic understanding of the mechanics of flight. The Gossamer projects had spearheaded a new era where computational work was becoming increasingly important, especially in nailing down the precise aerodynamics and lift required. That, and improving efficiency really made human powered-flight move from sustained hops and skips to the international crossings of the Albatross. With these two major challenges achieved, the Kremer prize would look to new and different areas to encourage eager engineering teams to explore. Next up? Speed.

No doubt spurred on by his success, Langford would soon be instrumental in a new project that would represent a definitive milestone for HPAs.

Kremer's world speed competition would keep things much simpler: a triangular course to be completed in less than three minutes with a pot of £20,000 for the first to do so. Prizes of £5,000 were also given to subsequent attempts that beat the previous best time by at least 5 percent (until the total prize fund of £100,000 was exhausted). MacCready fielded a team, this time with an entry called the Bionic Bat, which featured a design much closer to modern light aircraft, incorporating a rear propeller and a more robust pilot gondola. One of the other competitors in the competition was MIT grad John Langford. Langford had been part of MIT's 1979 Chrysalis project that resulted in a biplane design that enjoyed a modicum of success — a project MacCready had also played a small part in. Now, the two would field competing craft in a bid to claim the first — and substantially bigger — Kremer world speed prize.

On May 11th, 1984, Langford's team with its Monarch B entry managed the course in two minutes, 54 seconds, earning it the £20,000 pot. MacCready's Bionic Bat would go on to beat this time by getting around the course in two minutes, 43 seconds just over two months later, on July 18th. No doubt spurred on by his success, Langford would soon be instrumental in a new project that would represent a definitive milestone for HPAs.

Daedalus Soars Again

If you're planning a world-record human-powered flight, it's probably more motivational to name it after the Greek mythological character that didn't fall into the sea. Nomenclature taken care of, Daedalus would attempt to follow in its namesake's wing-steps, and fly from Crete to the island of Santorini. The team behind the project was made up of MIT students — lead by Langford — but also had support from the Smithsonian Institute, NASA and the Greek government. After a couple of successful prototypes, the team settled on the final design — known as Daedalus 88 — which weighed just 68.5 pounds, despite sporting a 112-foot wingspan.

Daedalus takes to the skies
Daedalus takes to the skies.

The record-breaking flight would lift off on April 23rd, 1988. The team had held out, waiting for the absolute perfect conditions for the lengthy crossing. While weather may have been good at the launch point, with potentially four hours of flight time, it needed to remain calm for the whole distance. A team of pilots had been operating a standby rota, and the honors on this occasion fell to Greek cycling champion Kanellos Kanellopoulos. With just a sheet of Mylar polyester plastic between him and the ocean, he launched with a 3 MPH tail wind. Fortunately for him conditions held, and Kanellopoulos arrived at Santorini — a distance of 72.4 miles and some three hours, 54 minutes and 59 seconds later. Despite a safe voyage, Kanellopoulos' attempt at landing on the beach saw him fly into some head wind causing him to crash into the sea just feet from his intended destination. Once safely ashore, however, Kanellopoulos and Daedalus could lay claim to two world records: the longest human-powered flight, and the longest duration of a human-powered flight - records that still stand today.

It's not just the world records that continue Daedalus' legacy. Langford is still in the business, working for Aurora Flight Sciences, along with other MIT alumni. Many of their products — largely UAVs for commercial and military use — owe more than a passing nod to Daedalus. Many more craft have flown since then, and continue to fly, but the Gossamers and Daedalus represent what many consider the defining moments in HPA.

Human-powered Flight Today

Team AeroVelo's Snowbird Ornithopter.
Team AeroVelo's Snowbird Ornithopter.

There's still a lot of work going on in the area of muscle-powered flight, particularly of the rotor-driven variety. And while winged craft had Henry Kremer as a benefactor, using his challenges (and rewards) to advance their designs, the helicopter world has the American Helicopter Society and the Sikorsky Aircraft Corporation. The result is the Sikorsky Prize, and much like the Kremer deal, there's a lot of money on the table for the first team that can meet a set of prescribed goals. The prize was initially $20,000 when it was first set up in 1980. But, due to the lack of successful designs, this fund has since swollen to a substantial $250,000. This has evidently proven to be a good motivator as, right now, there are at least two teams tantalizingly close to claiming it for themselves, both of them with some great heritage.

Sikorsky Prize Requirements: "The flight requirements shall consist of hovering for one minute while maintaining flight within a 10-meter square. During this time, the lowest part of the machine shall exceed momentarily three meters above the ground."

Team AeroVelo and the Atlas

Before working on a human-powered helicopter, Cameron Robertson and Todd Reichert were already making waves in the HPA scene. Airwaves to be precise. The pair worked together on the Snowbird ornithopter. Historically, these wing-flapping machines haven't fared so well. That all changed with Robertson and Reichert's mind-blowing project, which managed a sustained flapping-wing flight of 19.3 seconds — a world's first. It was a good reminder of exactly how far things have come since the gold-rush era around the '70s and '80s, especially with a project as complex as Snowbird.

"[With Snowbird] there was a lot of hand design, but a lot of the work behind it was very computationally intensive. And that's the sort of thing that in the '80s would have required crazy supercomputers," says Robertson.

Buoyed by their initial success the duo decided to take on the human-powered helicopter (HPH) challenge with their latest project: AeroVelo. As team AeroVelo, Robertson and Reichert are currently working on Atlas, a rotocopter they hope will earn them the coveted Sikorsky prize. Atlas is about twice as big as any previous HPH, and uses some of the same design optimization that was born out of the Snowbird project. Modern projects profit — almost literally — from other technologies too, with Atlas being funded by a recent Kickstarter project.

Atlas — Flight Testing.
Atlas — Flight Testing.

Since the Kickstarter success (it's raised $4,000 more than the requested $30,000), the team behind Atlas has been hard at work refining its design, and recently completed a successful 17-second flight. This might be some way off from the full 60 seconds required to nab the prize, but Robertson and Reichert remain quietly confident.

"We're hoping that in the new year, we might be able to get some flight testing in. We built a single-rotor test stand, so we can test one at a time and really, really refine things. The next time we go back to [full flight] testing we're going to be very sure of our numbers and our control systems. So there shouldn't be nearly as many unknowns," Reichert assures us. It looks like early 2013 could be a busy month for the American Helicopter Society, however, with at least one other team in hot pursuit of the prize.

The University of Maryland and Gamera II

With something of a head start on AeroVelo, the Gamera team at the University of Maryland started work on its HPH more than four years ago with the very definite goal of winning the Sikorsky prize. The all-student project began in 2008 at the A. James Clark School of Engineering, which led to the development of the original Gamera HPH. This culminated in a — then record-breaking — 11.4-second flight in July 2011. Although this was good progress, to stand a chance of winning the Sikorsky prize, a more streamlined design would be required. So, going back to the drawing board, the Gamera team enhanced the rotor design, worked on improving the transmission and redesigned the cockpit, all as part of Gamera II.

"Structurally, the big challenge is making it as light as possible. Working with composite materials and advanced structural design to try to minimize weight. A lot of the innovation that's lead us to be successful on this project has been the structural design elements," Explained Project Manager William Staruk. "Our main problem at the moment is stability and control. How to keep the vehicle from drifting away or crashing into walls."

With a non-official flight of more than one minute apparently already in the bag, and a max height a whisker under the required three meters awaiting official verification, Gamera II certainly appears to have the main ingredients already taken care off.

"We think we're close to that three-meter combination ... we think we know how much power it takes to do it," Staruk added. "So we're having our pilots run on exercise machines on what we think the flight profile will be, and we gather that they're very close to doing it, and believe that they are capable of doing it."

Gamera II — University of Maryland
Gamera II at the University of Maryland.

So, if the team can stop the craft from drifting beyond that 10-meter square, it would seem they have everything to play for. So much so that they, too, are planning another attempt at the prize, also in early 2013. The main drawback actually has nothing to do with funding, resources, engineering or design. Instead, it's finding a location to test and perform such flights. With the outdoors being almost certainly too windy to run test flights, both Gamera II and Atlas are limited to the time they can secure in facilities large enough to host them. A trivial problem, but a very real one. Either way, before too long, the ink could by drying on a freshly cut check from the American Helicopter Society.

It's a shade more than 100 years ago that Robert Peugeot started the long-running tradition of inspiring progress in human-powered flight by reward. Over that time we've seen huge steps made towards an impossible dream: taking flight with just the power of human muscles (plus a bit of clever engineering). This goal has since grown to become a life's work for many. With big prizes still up for grabs, it's likely there are more chapters still to come. Not least, because, if one thing can be divined from the successes - and perhaps more so, the failures - it's that something deep within human DNA yearns to take to the skies. The unconvinced only need to look to the innocent flugtags, to see this desire manifesting itself in the most accessible form there is - fun social gatherings. Most people won't have the resources to go after a Kremer prize, but show them a YouTube video of colorful contraptions being launched off a pier, and there's a good chance they'll think - even if only briefly — that they could have a go at that. Some might even go so far as to fake it.

This piece originally appeared in Distro #75

[Image credits from top: National Archives, Andrew Dunn, SSPL/Getty Images, Leemage/UIG Via Getty Images, Aerovironment Inc, NASA, Aurora Flight Sciences, AeroVelo, AHS International, University of Maryland]