Is there a difference going from low speed to high v high to low?Tommy Cookers wrote: ↑Sat Oct 31, 2020 11:35 amit seems that .....
at max wt (181 tons start of takeoff) Vr was 197 kt 227 mph IAS (ie true speed higher in places higher above sea level )
rotation was 'long' ..... (meaning quite slow ?)
presumably C was aerodynamically unstable in pitch so before rotation elevators were giving nose-down pitch ie lift
and for rotation elevator force became reduced lift or downforce
so max tyre load would be at 227 mph
if we believe Capt. Hutchinson saying that C full weight is on wheels fuselage-level (unlike other airliners)
ie design is for best acceleration by having minimum wing drag ie no lift when fuselage-level
(rotation was to 13 deg to allow for engine loss - becoming 18 deg attitude in noise-abatement climb)
takeoff typically took 30 - 40 sec (11 - 13 sec in continuation training !)
C tyres didn't have a great record (Air France threw a tread causing fire and dubious 3 engine flight from the USA to France ?)
250 mph was apparently the 'safe' tyre limit for eg F105 F106 and F104 (this '240 kt' dead-engine landing)
shuttle touchdown 215 mph, SR71 242 mph, X15 similar
iirc Bob Hoover landed an F100 at 325 or so (the opening footage in the '6 million dollar man' thing)
btw pilots touch down with a deliberate bump on wet runways - the extra force helps wheels spin up and ABS to work
You know, heat soak v scorch from cold? Temp and pressure of the air inside ?