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Boeing 737 Unpaved Strip Kit (b737.org.uk)
87 points by yread 47 days ago | hide | past | web | favorite | 9 comments

Great video by Sam Chui about this posted a few days ago: https://youtu.be/csnaMnpU_BU?t=57

wow that _is_ great!

Didn't know this existed. Even with planes that were built for dirt runways (c-130, c-17) there can still be issues.

I worked briefly as a mechanic for Boeing on C-17's. One incident (I did not witness but was told) was a C-17 somewhere in the middle east landed on a clear patch of dirt/sand, except right when they touched down they noticed a small concrete barrier in the middle of the field...

The nose gear went right into it. It was narrow enough to miss the rear tires. But the impact of the nose gear ripped it complete off the plane and left a gaping hole where once the fuselage touched, blasted a ton of sand straight into the interior of the plane. I think a specialty crew eventually made it out there and rigged a nose gear together good enough for a take off and landing where it then flew back to a Boeing facility near Lackland Air Force Base (I believe).

The vortex dissipators are interesting! Hard to imagine that gravel or dirt wouldn't get tossed into the jet intake and cause massive damage. Their solution is three air jets blowing air down and aft from the front of each intake at 55psi, which apparently worked. I wonder though if despite this gravel sometimes still went through and damaged turbine fan blades.

Yeah, I also find it hard to believe that gravel doesn't get sucked into the jet intake. The Sam Chui video mentioned above is fascinating and shows the system in regular use in northern Canada.

The aviation stack exchange has an article with pictures of the vortices created by jet engines: https://aviation.stackexchange.com/questions/21219/how-does-... . Basically jet engines create low pressure air near the ground and the dissipators cancel it out by supplying air. I imagine the dissipators point aftwards because the engine passing over the ground acts like a venturi and so the low pressure region is directly under the engine. I originally thought the intake would be creating low pressure..

The vortex dissipators are aimed at preventing the engines from forming vortices that would suck up gravel from directly below, like the ones you see in this video:


On the 737-200, I think the engines sit far enough back in the nacelles that the won't be able to suck in anything form below if the vortices don't form:


Really cool.

The Lockheed LC-130 Ski-bird is a cool aircraft conversion too


Decades ago, I used to skydive out of a small airport in Florida [1] with a dirt/grass runway, albeit a very long one, over 6000 feet. Nothing flew out of there except for the jump plane and crop dusters. One day, the jumpers were surprised to see a fully equipped 737 on the dirt runway. We found out it was running trials for unpaved runway landings as an unnamed African customer had requested.

[1] https://www.airnav.com/airport/X58

That's awesome. I want to see a 737 land at our local grass strip (yes, I read the limitations, and know it's impossible).

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