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Space Shuttle: Difference between revisions
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→Control cross couplings
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Control surface effectiveness in general drops with increasing Mach number, however the speed at which this happens is different for elevons and rudder. | Control surface effectiveness in general drops with increasing Mach number, however the speed at which this happens is different for elevons and rudder. | ||
=== Aerodynamical DAP schemes === | |||
There are two different control schemes available for the aerodynamical part of the Shuttle's flight - one of them based on the real Shuttle DAP, the other educational. | |||
; Aerojet | |||
: The Aerojet DAP is closest to what the real Shuttle uses. It is a scheme in which the stick commands pitch and roll rates and stick in neutral position commands attitude hold. Above Mach 3.5, in addition an automatic pitch control mode can be activated which maintains the scheduled safe entry AoA. Flying the Shuttle is very easy in this mode - there is no operational need to use trim or rudder and response to control input is crisp and precise. During entry, Aerojet can manage even agressive roll reversals inside the stable region. | |||
; Aerodynamical | |||
: This is an educational mode in which the Shuttle is flown similar to an airplane, i.e. the stick basically controls the airfoil positions, and in order to achieve level flight with stick neutral, trim has to be used. Since the Shuttle is yaw-unstable at high Mach numbers, this mode still has automatic stability augmentation, i.e. rudder and ailerons are commanded automatically to minimize sideslip. Entry can be flown with this mode starting in-orbit with <b>RCS ROT ENTRY</b> and illustrates the amount of work the rate controller has to do as well as gives a hands-on feeling for hypersonic aerodynamics. This however is somewhat challenging and it is possible to maneuver the Shuttle outside its stability envelope using too agressive maneuvers. Once below Mach 5, the Shuttle responds well and stable to direct aerodynamical control. | |||
=== Entry and touchdown structural and aerodynamical limits === | === Entry and touchdown structural and aerodynamical limits === | ||