Category: Aviation

The field of human-powered flight achieved an unlikely milestone yesterday when, for the first time, two independent teams went head-to-head in an attempt to win the Sikorsky Prize. Unclaimed after 22 years, the Prize—a human-powered hover of 60 seconds and an altitude of three meters altitude while remaining within a 10-meter square box—has long been believed by many aeronautists to be flatly impossible to attain. But recent achievements have convinced most observers that not only will the prize fall, but it will fall soon.

Before this year, attempts were few and far between, with only three machines ever managing to leave the ground. In 1989, a craft built by students at Cal Poly San Luis Obispo stayed airborne for 7.1 seconds. Five years later, Yuri I, built by students at Nihon University in Japan, flew for 19.5 seconds. After a dormant long period, the prize was reinvigorated in 2009 when the Sikorsky Aircraft Corporation bumped the prize amount up from $25,000 to its present quarter million. Last year, a team from the University of Maryland’s A.J. Clark School of Engineering achieved 11.4 seconds with a machine dubbed Gamera.

Given all those anemic results, it’s no wonder skepticism remained rife. But this summer the Gamera team fielded a larger, lighter-weight version of its earlier machine, this one called Gamera II, that quickly racked up a string of stunning achievements. This past June, the team upped their best time to an astounding 50 seconds, then in early August improved that to 70 seconds. The duration requirement was in their grasp, but could they pull off the altitude? A three-day visit by an official from the National Aeronautic Association, who could certify a bid for the Sikorsky Prize, was scheduled for Tuesday, August 28 to Thursday, August 30.

Meanwhile, 300 miles to the north, a secretive insurgent campaign was underway…

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For years, aeronautical dreamers have extolled the promise of hybrid airships—blimp-like aircraft that rely on a combination of buoyant gases and dynamic lift to fly. Such a craft, they say, could achieve the efficiency of a lighter-than-air vehicle and the controllability of a conventional airplane—but repeated attempts to fulfill this vision have so far come to naught.

Earlier this month, however, Northrop Grumman achieved the first flight of what may well prove to be the first operationally successful hybrid airship. The Long Endurance Multi-Intelligence Vehicle, or LEMV, is a 300-foot-long triple-hulled blimp scheduled to be deployed to southwestern Asia next year, where it will loiter at 20,000 feet for up to three weeks at a time, providing a round-the-clock surveillance-coverage capability equivalent to that of 25 fixed-wing drones. Northrop Grumman provided PM these exclusive images of the blimp during its initial testing phase in Lakehurst, N.J.

The LEMVtook off for the first time in the late afternoon of August 8 and flew for 90 minutes. Although the craft is designed to operate autonomously under the guidance of its own control system, two Northrop Grumman employees occupied it during the flight test.

French aviation authorities have released the final report on the June 1, 2009 crash of Air France 447, one of aviation’s most dramatic and troubling disasters. And though earlier reports painted a fairly clear picture of what transpired, there is one surprise in the final documents—the extent to which the authorities blame not mechanical failures but the actions of the flight crew. The Bureau d’Enquete et d’Analyse (BEA) suggests that the accident “shows the limits of the current safety model.” That is, there is an element of fatal risk so deeply baked into modern aviation that it may be unfixable.

A quick recap of the Air France investigation: As PM’s December 2009 cover story reported, suspicion initially centered on the aircraft’s pitot tubes. Data sent by the aircraft in the moments before its disappearance suggested that these airspeed sensors had iced up and stopped working. Most aviation experts assumed that the pitot tubes’ failure and the severe weather (the crew had flown into a severe thunderstorm) were the key factors in this disaster.

But when searchers finally recovered the plane’s flight data recorder and cockpit voice recorders (commonly called black boxes) from the ocean depths in early 2011, those recorders painted a much different picture. Investigators determined that the loss of airspeed was in fact a minor hiccup that would not have endangered the flight if pilots had followed proper procedures. What doomed the flight was a series of almost incomprehensible mistakes on the part of the flight crew. Two were particularly astounding. First, a co-pilot at the controls pulled the plane up into a climb—simply leveling out the aircraft could have saved it. Second, he and the two other pilots on the flight deck failed to realize that, as a result of climbing, the plane had entered an aerodynamic stall and began plummeting toward the ocean.

The BEA’s final report offers revealing insight into the psychological factors behind these failures. Continue reading The Limits of Aviation Safety

The endurance record for a human-powered plane is nearly 4 hours, set in 1988 when an MIT-built plane pedaled 70 miles from Crete to Santorini in Greece. The longest a human-powered helicopter (HPH) has been able to stay aloft? Nineteen seconds.

This pretty much tells you what you need to know about the challenge of building a human-powered helicopter, which remains one of aviation’s great unsolved challenges. Aeronautical dreamers, however, are a dauntless bunch. Their ultimate goal is the Sikorsky Prize, a $250,000 purse established in 1980 that will go to whoever can build an HPH capable of staying aloft for at least 1 minute and reaching a height of 3 meters (10 feet). Now the team behind the successful ornithopter, the Snowbird, is trying for the Sikorsky Prize—and asking for the Internet’s help.

You may remember Todd Reichert as the man who headed the University of Toronto’s human-powered ornithopter project and pedaled the aircraft during a series of successful flights. (He was also in the news more recently as one of the leading voices in debunking the Jarno Smeets video hoax before its perpetrator finally confessed.) Now a newly minted Ph.D., Reichert has joined Cameron Robertson in forming a group to assemble a machine they call Atlas. As of today, the project is nearly halfway to its $30,000 Kickstarter goal, with 15 days to go.

It’s a fair chunk of change for a few seconds of flight. But building a human-powered helicopter is an extraordinary endeavor. To stay aloft, any aircraft must push air down. The engineer’s choice is either to push a small volume of air down very quickly (like a Harrier jump jet’s turbines) or a large amount of air slowly (like a glider’s long wings). The latter is vastly more efficient. Unfortunately, if you want to hover in a helo, that means you have to move a huge amount of air, so your rotors have to be exceedingly long. Long rotors mean more weight, which means you need more lift, which means you need longer rotor blades. Reichert estimates that a viable Sikorski Prize contender would need to be the size of a Boeing 737, yet only weigh about 100 pounds.

That’s why the contestants so far have all fallen so short. In the three-plus decades since the Sikorsky Prize began, only three craft have managed to get off the ground at all. The most recent contender to achieve this modest goal came from the University of Maryland, which last summer got a craft dubbed Gamera off the ground for 4.2 seconds. That team is now working on a followup, Gamera II, that has been reengineered to be lighter and stronger.

Reichert and Robertson will try to top that by optimizing every inch of their craft through computer-model testing and pushing materials science to its limits. Atlas will consist of four rotors arranged horizontally in a diamond configuration, with the piloted seated in the middle. Each two-blade rotor will be constructed of foam and balsa ribs on a central spar made of carbon-fiber tubes. “We test these tubes to failure,” Reichert says. “That way, we know we’re using the smallest amount of material to hold the most amount of weight.”

Read the rest of the article on the Popular Mechanics website.

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We’re in the front seat of a helicopter, thumping along 1500 feet above the foam-flecked waves of the Gulf of Mexico, when pilot Chuck Aaron does something you’re never supposed to do. He pulls back on the controls and just keeps pulling. When the helo’s nose rears up, I feel my body sinking into the seat as my heart crawls up my esophagus. We keep going until all I see is blue sky, then the line that separates it from the greener blue of the gulf. A little voice in my head is saying huuuunh? and the weight of an implausible yet true realization sweeps over me: The rotors are now below us, the landing skids above. We are flying upside down.

There’s a reason why you should never, ever fly upside down in a helicopter: The rotors will bend toward the skids and cut off the tail and you’ll plummet to your death. Helicopter rotors are designed to handle a lot of flexion, because each blade has to bend up and down as it moves into and against the slipstream. In normal flight, the blades bend away from the cockpit. But if you fly upside down, they flex in the other direction, giving a whole new meaning to the word chopper.

Aaron, a 63-year-old with a mane of golden hair and a bushy mustache fit for a circus ringmaster, knows all about this. He was a helicopter pilot and mechanic living in Camarillo, Calif., when he got a call from Red Bull in 2004. They’d heard that he’d assembled a U.S. Army attack helicopter from parts scrounged on the open market. They asked him: Could he build a helicopter capable of looping the loop? “No,” he told them. It was impossible. End of story.

But Aaron kept mulling it over, and he thought that if you took the right kind of helicopter and modified it in just the right way, you might wind up with an aircraft that could fly upside down. Red Bull gave him the money, and he bought a pair of German BO-105 helicopters with rugged one-piece titanium rotor heads and four short, stiff composite blades. After a year of modifications—he refuses to reveal the engineering details—he took his helo up. Continue reading Going Upside-Down in a Helicopter

Gizmodo posted a pretty incredible story on March 21, 2012, entitled “Man Flies Like a Bird Flapping His Own Wings.” It claims that a Dutch inventor named Jarno Smeets has built and successfully flown a powered flapping-wing contraption. Accompanying the post is this video, which shows Smeets apparently doing a short run-up and then soaring into the air in an urban park:

My friend John Cook at Gawker alerted me to the story by Twitter, and asked for my input. My immediate reaction was: this doesn’t pass the sniff test. At all. For a couple of reasons:

1)  The machine that Smeets built is called an ornithopter — that is, it propels itself by flapping its wings. Ornithopters are an ancient dream, dating back to the Greek myth of Icarus, but have proven incredibly hard to pull off; it’s a matter of debate whether any human-carrying ornithopter has ever truly flown. I wrote about one attempt a while ago; you can read about it here.

2) Given the difficulty of the undertaking, it would be astonishing if this guy managed to eke out a small altitude gain. In contrast, he freakin’ soars. That’s a steep climbout. This guys has power and performance to burn. First time on a back-mounted ornithopter with a short wingspan and practically no visible powerplant? I doubt it.

3) Maybe a small thing, but: why do his friends run away from his flight path? Wouldn’t they want to see what happens, and maybe help him if necessary? (Look at where people are standing in those iconic photos of the Wright Brothers taking off). Also, why are they so giddily happy? He hasn’t done anything yet, dudes.

4) My biggest annoyance with this story is all the talk about how he linked together “an Android phone and Nintendo Wii controllers” in order to accomplish this amazing feat. To me, that’s a huge red flag: to rig a contraption this way would mean being incredibly clever to be incredible stupid. If you’re going to amplify human motion through power boosting — as the Pentagon has long been investigating, in hopes of building real-world “Iron Man”-type powered suits — the biggest problem by far is the issue of latency. Basically, the machine needs to correct its output virtually simultaneously with your altered input. Sensing someone’s motion using a Wii is a ridiculously complicated and latency-adding approach when you could much more easily do it the way engineers have been doing it in aviation for more than a century: using cables or push rods.

To its credit, Gizmodo has incorporated some skeptical takes in its updated version of the story. Still, the fact that it promoted this hoax in the first place is evidence of its credulousness.

UPDATE: The perpetrators of the hoax quickly gave up the game. In the aftermath, I interviewed a real, live ornithopter pilot for the Pop Mech website about why such craft are so difficult to pull off.

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One of the more interesting responses to my recent Pop Mech piece on Air France 447 came from the Atlantic Wire, which took my description of the sounds and smells that the pilots experienced as a point of departure to discuss what the flight’s final moments must have felt like for those in the cockpit. Here is a photograph that accompanies the post, showing the electrical phenomenon known as St. Elmo’s fire. I’ve never seen such a thing in real life, but imagine that it must seem both beautiful and worrying.

Thanks to the cockpit voice recorder, we have a pretty good idea of what the pilots heard, and the instrument data gives us a pretty good idea of what they saw. But what about the passengers in the back? Their perspective was very different, so I’d like to offer a few speculations about what the final moments of the flight might have been like for them.

The plane had taken off from Rio de Janeiro at 7.30 in the evening, local time, and had been flying for about four hours when it first encountered the weather system that would precipitate the final crisis. It was nearly midnight, then, by the internal clocks of most of the passengers; a few were probably reading, or watching a video, while the majority were probably sleeping, or lightly dozing. The captain himself had just left the cockpit to go take a nap.

As the flight neared the line of massive thunderstorms straddling the Inter Tropical Convergence, any passenger who happened to be awake would probably have felt some light turbulence. Those looking out window would have watched the plane fly into a bank of clouds, then out into clear sky, and then back into clouds. At six minutes past midnight, one of the co-pilots made a call back to the head flight attendant, alerting her that the plane would shortly be entering an area of turbulence. He made no such announcement to the passengers, however.

The turbulence grew worse. In the cabin, the flight attendants would have been strapping into their seats. Continue reading What AF447’s Passengers Experienced