Half a croissant, on a plate, with a sign in front of it saying '50c'
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Brake-Assisted Launch

Chocks Away! Hit the Brakes!
  (+7)
(+7)
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To launch the very heavy aircraft now standard on US aircraft carriers the complexity and power of beneath-deck catapult systems has reached a remarkable (but largely classified) level. The forces acting on the front wheel strut and 'tug point' are extreme during launch accelleration. How to spread that load among all three parts of the undercarriage?

The answer could be to use an accellerator belt, resembling a long, wide conveyor belt. With the belt stationary, the aircraft is positioned for launch at the start of the belt and tethered with a slip ring attached to a reinforced point ventrally. The belt is spun up to a speed somewhat greater than the calculated lift-off speed for the type of aircraft and payload, with the direction of travel of the belt being from rear to front. At this point, the aircraft is sitting motionless on the belt, with its wheels spinning furiously backwards and its engines pitching up to full power.

To launch, pop the slip ring and Hit The Brakes!

ConsulFlaminicus, Feb 15 2006

Modern Steam Catapult http://www.c3f.navy...ln_JTFEX_Photos.htm
[ConsulFlaminicus, Feb 15 2006]

[link]






       I'm thinking if you hit the brakes on a belt moving over 150 mph you'd skid out of control, rock backwards, melt the belt with the exhaust and attempt a near vertical launch without the benefit of stabilizers.
Shz, Feb 15 2006
  

       So, [shz] an obvious bun then [+]
coprocephalous, Feb 15 2006
  

       Still trying to decide if that would be fun or not. :)
Shz, Feb 15 2006
  

       Nuclear powered carrier, steam catapult. Something's wrong.
ldischler, Feb 15 2006
  

       No, the nuclear power is used to generate steam to propel the ship and drive turbine generators, so it is efficient to also use it to drive the huge pistons that form the catapults.   

       [Shz] Good point. Solved by having the aircraft adopt a pronounced 'nose down' posture prior to release - the engine thrust and a controlled 'pop' of the nose wheel strut during the launch will see the plane in correct attitude by the end of the belt.
ConsulFlaminicus, Feb 15 2006
  

       I think there was also a Westinghouse linear motor catapult, but I suspect it is easier to route steam than huge electrical currrents.
coprocephalous, Feb 15 2006
  

       sometimes I think I need a brake-assisted lunch.
po, Feb 20 2006
  

       I'm about ready for a lunch brake too.
wagster, Feb 20 2006
  

       Two big pink hands. One holds the calapult, the other draws the plane back, then lets go.
spidermother, Feb 20 2006
  

       Yeah, give that lady a bun!
wagster, Feb 20 2006
  

       Could they actually use the hook from braking a landing craft to wind up a flywheel that launches a craft that's taking off?
theircompetitor, Feb 20 2006
  

       They could, but I don't think I'd want to be on the flight deck crew. I've heard some stories of what it's like when the equipment breaks...
normzone, Apr 24 2006
  
      
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