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wrote:
I'm assuming there is no "weight" limit on the catapult. The immagine the catapult would have a broad specification of 1 firstly the force it can generate at say zero speed. 2 secondly the maximum speed it can reach. 3 maximum power it can transfer. 4 the amount of energy it can transfer (I assume there is some kind of steam reservoir or accumulator) There might be a weight limit on the deck. I see no reason say a 160,000lb aircraft can't be launched so long as it can be accelerated to above its stalling speed which of course needs to be lower the larger the aircraft gets. In the 1930s the Germans were catapulting the 38,500lb 4 engined Blohm & Voss Ha 139 using a pneumatic catapult. http://www.century-of-flight.net/Avi...s%20Ha.139.htm The theoretical limit would be the total energy (E=mv**2) that can be transferred in the distance allowed by the cat stroke. With a constant-pressure system, the force applied is essentially constant, so the acceleration would also be essentially constant. Theoretical max force at the cat piston would be the max (nominal 1200 psi) steam pressure of the ship's system times the surface area of the piston. Acceleration would then be inversely proportional to the mass of the airplane (F=ma), so end speed would be limited by total energy available. If you know the steam pressure, diameter of the cat piston, and the length of the stroke, you could calculate a theoretical max force applied, and then the max energy available. Of course, system friction losses and component limits would reduce that somewhat. Mass of the airplane would be limited by required end speed (stall + margin - headwind). |
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