why aircraft dont use ABS system???
In airplanes, there were early and later (more modern) anti-skid systems - Early 707 had the Mk.2 antiskid system - Later 707-320B and C had the Mk.3 antiskid (much better) - The difference.? In the Mk.2, if a wheel started skidding (slowing its rotation) the antiskid released brakes completely - Then after wheel regained rotation (not skidding) anti-skid operated again - In the Mk.3 the antiskid valves were FULLY MODULATING - Releasing brake pressure as needed to regain wheel rotation, but never stopped braking action - Obviously all modern airplanes have fully modulating anti-skid system - I do not know if automobiles with ABS have that.?
ABS is an acronym for Anti-skid Braking System. It's pretty much the same kind of system used in cars AND airplanes.
Antilock brakes in vehicles and anti-skid systems in airplanes operate on similar principles but are vastly different in lots of ways. Aircraft with anti-skid systems use hydraulic pressure supplied by the aircraft hydraulic system. The master cylinders are really pressure regulators attached to each brake pedal. The antiskid uses a second processor-controlled regulator to relieve some of the pressure if a skid is detected. The fluid that is valved off is returned to the hydraulic reservoir. Antilock brakes in cars operate like normal direct-hydraulic brakes with a master cylinder. If a wheel locks the pressure is relieved but a motor-driven pump starts up to maintain fluid flow and pressure while the antilock valve is open. The antiskid system in a MiG 21 is nothing short of amazing. The brakes are pneumatic. A small chamber is mounted on the strut in the pneumatic line to the brake. This chamber contains a small poppet valve in a relief port held in place by a calibrated spring. If the wheel skids the tire chatters, shaking the strut. This shaking is enough to unseat the poppet valve, releasing nitrogen pressure until the wheel starts rotating again and the chattering stops. At that point the spring can once again hold the poppet valve shut. No computers, networks of valves, plumbing, sensors, nothing but simplicity. That is genius.
