VC-25A
airguy said:
Keep in mind as well that the 747 aircraft used by the president is, shall we say, "modified" somewhat. I remember them talking about his departure on the plane immediately after the 9-11 attacks, the pilots took it from runway directly to FL430 in 17 minutes. That's definitely not stock performance, even empty.
Greg I can't confirm or deny that performance is special. I was working for Boeing when the current VC-25A, a B747-200B went out the door. It was actually pretty stock, except for the fact they where not making -200 passenger planes anymore at the time and it flew off green, to be be final fitted.
Building VA-25A in Everett Washington in the late 80's was a low key affair at Boeing, and there was no special attention brought to the plane on the production line. There are special systems which are not discussed, but performance wise not sure there is much extra there, except light weight and full power on later model GE CF6 engines. The B747SP (special performance) is the real hot rod of B747. Its was a real short B747 for long range flight. Not many where made, but they where really overpowered.
The engines are GE CF6-80C2B1, 56,700 pound thrust, each. That basic CF6 engine core can go from 40,000 to 72,000 lbs thrust. 56,700 lbs is more than the standard engines found on the original B747-200's, so its a little overpowered. With the lighter weight, bigger engines no doubt its a hot rod. Who knows it may have something special (top secret) that gives them more power than advertised to the general public?
When flying a large jet at light weights it's standard practice to de-rate the power up to 25%. For example taking off with an empty B757 with light fuel is ridiculous. The extream rate of ascent and pitch angle is too extreme, it makes leveling off at lower altitudes after departure difficult, unless negative G's are involved. If airline flying did light weight max power takeoffs it would be very uncomfortable for passengers. It's not something you normally get to do, max effort climb at light weights with no altitude restrictions. Most climbs from takeoff to cruise to the mid 30's involve several level offs, at least one or two. Sometimes in the middle of the night you get unrestricted climb to cruise altitude after takeoff.
Remember you have 2 or 4 engines and can fly at gross on 1/2 your engines. So light with full power is a ride.
The interesting thing was Boeing won the contract based on the -200 even though the B747-400 was being made. The reason is, the President's plane (only called Airforce one when the commander in chief is on board) must have had a number of years of proven service, which eliminated the -400 for consideration.
Its possible the president will be flying in C-32, the B757, VP's plane. That field is well within the B757 capability. If they go into the field with a B747 it will be light fuel. Do we tax payers have to pay for the Pres to thump on the campaign trail? Hummmm
