Date: 28 Dec 96 14:20:08 From: "Dave Starr" <email@example.com> Organization: Base Exterminating - Out, Rodent! References: 1 2 3 4 5
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...... > I dont see a cargo ramp as being much more complex then a standard > cargo door. Bigger hinges/etc, but not that much more complex. > And while there is some wieght penalty, the cargo door is shoved > up under the tail, which is usually just 'wasted' space anyway. > Being able to just slide the pallets right out the back and onto > a truck is much more efficient then slide one out, scissor lift it > and then slide it onto a truck. There are some good points in this and the earlier messages in the chain, but a bit of apples vs oranges has crept in here. The cargo pressure door, ramp, and petal doors on the C-17 (and the C-5 and C-141 predecessors) are extremely complex, heavy and maintenance intensive. They are built to accommodate heavy equipment (loaded trucks, main battle tanks, etc.). There is no denying that a roll-on/roll-off setup would be more efficient for a carrier like FedEx, but the current military cargo ramp system would be a terrible match for the job. It's illuminating to note that unofficial Air Mobility Command (formerly MAC) rules of thumb count a KC-10 (high-mount, side cargo door only) as equal to 1.5 to 2 C-5s in efficiency - mainly because the complex systems of the C-5 (especially the front and rear cargo doors and kneeling landing gear) break so often that the KC-10 delivers more tonnage in a given time frame. (argument invalid if considering cargo such as main battle tanks). Lockeed made serious attempts to market civilian versions of the -141 and -5 with little success. The L-100 civil Hercules has attained some success with a rear cargo ramp, but also without petal doors.