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

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-this-vortex-form-inside-a-jet-engine 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..