That makes sense, (that's why I questioned how true it would be.) But, as you alluded to, what's the average delta between max-takeoff weight and max-landing weight? Do bigger jets usually have a much bigger spread than smaller jets? And of course, it's all tempered with how long the runway is. ;-) Matthew On Jun 27, 2004, at 9:24 AM, Kees de Lezenne Coulander wrote: > Matthew Montano <mmontano@xxxxxxxxx> wrote: > >> Most large aircraft do have the capability, by the nature that as a % >> of their total weight, the fuel is a significant junk. >> >> DC-10s/MD-11s, as do 767s, 747s, 777s. >> >> Someone visualized it for me that if a large aircraft landed that was >> almost full of fuel (if it could hold any sort of glide path) would >> stop when the wheels touched the ground; but the wings would keep >> going. >> >> Boom. >> >> Not sure how true that would be though. > > Any aircraft certified to FAR Part 25 should be able to do > considerably > better than that. The landing gear and the rest of the structure > should be able > to withstand landing loads generated by a vertical speed at touchdown > of 10 > ft/sec up to Max Landing Weight and 6 ft/sec up to Max Take-off Weight. > > This requirement ensures that all airliners are structurally sound > to > withstand a landing at Max Take-off Weight, provided the circumstances > allow > a halfway decent landing. Any landing above Max Landing Weight will > nevertheless trigger a heavy-landing inspection, keeping the aircraft > out of > service for a little while. > > A fuel dump system is purely a performance issue. It is required, > unless the > aircraft can maintain required approach and landing climb gradients at > up to > full take-off weight. These climb requirements are intended to ensure > that the > aircraft can climb away from an aborted approach, even with one engine > inoperative (provided the landing gear is still capable of retracting). > > Formulated this way, it actually becomes a design trade-off: either > fit a > fuel dump system, or provide some excess thrust. In practice this > means that > most long-range airliners have fuel dump systems, while short-range > aircraft do > not. > > The foregoing should not be taken as a promotion of overweight > landings; it > is just intended to debunk the myth that aircraft fall apart when > landing > above Max Landing Weight. Operationally, it is a command decision to > accept the lesser of two evils: either spend the time to dump fuel or > burn it > off, or accept the lower safety factor of an overweight landing. > > Kees de Lezenne Coulander > > > C.M. de Lezenne Coulander > Aircraft Development and Systems Engineering B.V. > Hoofddorp, the Netherlands