From: firstname.lastname@example.org (Dick King) Date: 28 Jun 94 14:33:20 References: 1
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In article <airliners.1994.1373@ohare.Chicago.COM>, email@example.com writes: |> I suspect any aircraft can be used for zero-G parabolic flights; ... Aerobatic aircraft have various features that allow them to pull negative Gs. They use fuel injection, etc. rather than carbs with their float valves, but one of the more interesting adaptations is that some of them have rubber bladdars within the fuel tank, so that as fuel is consumed the bladdar just gets smaller and all of the air enters the tank outside the bladdar. If you don't do this then the engine might get air bubbles or even pure air as the fuel outlet ends up above the fluid level. Zero G is not negative G, of course, but it could become -0.001 G, at least accidentally, and air bubbles can be a problem even at real zero G. Deep space spacecraft are often designed to perform a large burn when they get near the planet they're designed to explore. The zero G fuel flow problem is solved in one of two ways: * Spin the spacecraft. You need to have the fuel outlet on the outermost and rearmost corner of the tank. That way, the outlet is below the fluid level both before thrust builds up and after. * have a small burn of some manouvering jet before the main burn. It doesn't take much to settle the fuel.