August 28, 2012
Yesterday the National Transportation Safety Board released a synopsis, subject to further review and editing, of its findings on the September 2011 crash of a modified P-51 at the Reno air races that killed 11 people. “[The] probable cause…was the reduced stiffness of the elevator trim tab system that allowed aerodynamic flutter to occur at racing speeds.”
Peter Garrison dissected the phenomenon of flutter in his 2001 article, “The Hammer.”
Seldom reported and little understood, [flutter] occupies one of those dimly lit and unsafe places that decent people prefer not to visit. The idea that an airplane could shatter—disintegrate—for no reason other than its own motion through the air—better to let sleeping horrors lie.
Garrison went on to explain that flutter is a form of resonance, or sympathetic vibration, as seen in an out-of-balance tire. However, “Out-of-balance tires seldom lead to structural failure of the car because automobile suspensions are vastly overbuilt for the loads they normally encounter. But airplanes, which must be kept as light as possible, are not superfluously stout. They are capable of failing with sudden explosiveness when flutter sets in.”
In our April 1987 article on the Dash 80 (the prototype Boeing 707), test pilot Dix Loesch recalled that the Dash 80′s tail also was prone to flutter, and that “flutter was a black science then [in the 1950s]. When the flutter guys started talking to their bosses, everybody else just sort of looked at the ceiling.”
The vibration frequency of an aircraft section in the throes of flutter is so fast that it can’t be detected by eye. It’s visible only in slow-motion videos like these:
May 4, 2012
Caveat emptor for propeller-heads: This Lockheed Martin ship is not of the winged variety. And the U.S. government has been trying to get rid of it for years.
In the 1980s, the Defense Advanced Research Projects Agency, the U.S. Navy, and Lockheed Martin outfitted a twin-hull surface ship with the latest in marine and stealth technology. Sea Shadow had originally been built in the Hughes Mining Barge; it was designed, along with Hughes’ Glomar Explorer, to retrieve the Soviet ballistic missile submarine, K-129, which sank in 1968.
After a partially successful retrieval, the barge was towed to Lockheed Martin’s Redwood City site in California, where the re-outfitting commenced in 1982. After night tests off the Santa Cruz Islands in the late 1980s, the $50 million ship went public in 1993. Testing continued through 1999, with the barge and ship docked in San Diego; in 2006, both went into Navy storage. The radical design of Sea Shadow — its angular shape, like the panels on Lockheed’s F-117 stealth fighter, rendered it nearly invisible to radar — inspired a lookalike in the 1997 James Bond film, Tomorrow Never Dies.
The General Services Administration auction site is taking bids on Sea Shadow through 5:00 Central Time on May 4 (the bid as of late Friday morning was $299,085). You won’t be able to use it for transportation, however. According to the GSA, “The ex-Sea Shadow shall be disposed of by completely dismantling and scrapping within the U.S.A. Dismantling is defined as reducing the property such as it has no value except for its basic material content.”
April 4, 2012
Terrafugia recently flight-tested its prototype “roadable aircraft,” the Transition, accompanied by much media buzz about the next revolution in transportation [YAWN].
I applaud Terrafugia’s up-front marketing strategy: they have always marketed the Transition to pilots and those who are willing to earn a pilot’s license. The company has never claimed that road-ragers can untangle themselves from traffic jams by pressing a GO UP button in their Transitions and VTOL-ing up and away, like a scene from The Fifth Element.
But here’s the catch: All involved admit a flying car tends to combine the worst of both vehicles, so for $279,000, you get an underperforming car AND an underperforming airplane in one silly-looking vehicle. In its FAQs, Terrafugia notes, “If bad weather is encountered en route, the pilot can land and drive without worrying about ground transportation…”
Sounds nifty keen-o, but most pilots planning a cross-country flight will check the weather on their route, and prepare to file an instrument flight plan if need be; if they lack an instrument rating, they will schedule the flight for another day. I doubt they find much of an advantage in buying a so-so airplane with which they can land in case of bad weather and continue on in a so-so car. Why not just drive your car to the airport and fly your airplane, like pilots have done since dinosaurs roamed the earth? Not to be a Luddite, but If it ain’t broke, don’t fix it, especially with a $279,000 patch kit.
On the other hand, Maverick, the ITEC flying car, does make sense for missionary pilots, the military, poaching patrols, and powerline surveys. It’s a straightforward all-terrain vehicle with a parasail-type wing in which one can navigate dunes and grassland and skim over floodplains or other deal-breakers — for about $90,000.
I’m not bad-mouthing Terrafugia: their hearts and minds are in the right place. It’s just that the idea of a flying car has been around for decades, and there’s a reason why we don’t have one by now: no market beyond novelty buyers.
March 9, 2012
AND the company will pay you for the privilege, with a year’s worth of shop space, resources, mentorship and development aid in the Sikorsky Innovation Center in Stamford, Connecticut. All you have to do is submit a winning proposal, by March 30, on an innovation related to vertical-flight technology. Says Marianne Heffernan, Sikorsky Aircraft communications manager, proposals could easily come from people “who don’t even realize they have a technology…relevant to the rotorcraft arena.”
Details are here.
And fine-print stuff is here.
February 21, 2012
…with a nose job.
The Los Angeles firm Icon just sent out a press release about certifying its new Light Sport amphibian, the A5, as spin-resistant—an admirable quality for any aircraft. But older prop-heads will do a double-take at the A5 photo: It looks like a slicked-up Republic Seabee.
Let us wish for clearer skies for the A5, which Icon put together shortly after the Federal Aviation Administration created the Sport Flying class in 2004. Airplanes in that class, and their pilots, can be up and running in much less time, and with less expense, than standard lightplanes and pilots aiming for a private license.
Seabee sales suffered from bad timing in the late 1940s, as did those of many lightplanes marketed to returning World War II pilots who supposedly would want to continue flying—in their own airplanes. Those pilots had more pressing concerns, and the lightplane market tanked. The Seabee’s reputation for being overweight and underpowered also helped sink it.
The Icon will sell for around $140,000. Ads in Trade-A-Plane are asking around $40,000 – $50,000 for a Seabee. You can swap out the 215-hp Franklin engine for a more powerful model of recent vintage, and have gas money left over.
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