Aircraft landing gear prerotation system

A system for prerotating an aircraft's landing gear wheel prior to landing, comprising:

• at least one landing gear wheel attached to the aircraft by a support;
• means for measuring the true ground speed of the aircraft independently from the aircraft's airspeed;
• means for rotating said wheel at selective revolutional speeds while the aircraft is airborn;
• means for measuring said revolutional speeds of said wheel;
• control means for operating said means for rotating said wheel, said control means being responsive to said means for measuring the true ground speed and responsive to said means for measuring said revolutional speeds of said wheel, wherein said control means operates said means for rotating to selectively increased and decreased revolutional speeds of said wheel to correspond to the true ground speed, wherein said wheel has an impeller attached thereto, and wherein said means for rotating said wheel comprises a duct having a forward air intake and an air outlet, said outlet being directed towards said impeller to rotate said wheel, said duct having a variable gate therein to regulate airflow through said duct onto said impeller, said gate being openable by power means responsive to said control means, wherein said airflow through said duct and the rotational speed of said wheel is increased by increased opening of said gate;
• wherein said means for measuring the true ground speed comprises a Doppler radar unit on the aircraft.

A system for prerotating an aircraft's landing gear wheel prior to landing, comprising:

• at least one landing gear wheel attached to the aircraft by a support;
• means for rotating said wheel at selective revolutional speeds while the aircraft is airborn, wherein said wheel has an impeller attached thereto, and wherein said means for rotating said wheel comprises a duct having a forward air intake and an air outlet, said outlet being directed towards said impeller to rotate said wheel, said duct having a variable gate therein to regulate airflow through said duct onto said impeller, said gate being openable by power means responsive to control means for operating said means for rotating said wheel, wherein said airflow through said duct and the rotational speed of said wheel is increased by increased opening of said variable gate to selectively increase and decrease revolutional speeds of said wheel, wherein said variable gate comprises a pair of oppositely disposed hinged doors at said air intake and wherein said power means comprises an electric motor coupled to move gear means, said pair of doors being coupled to said gear means for opening and closing said pair of doors;
• and
• means for measuring the true ground speed comprising a Doppler radar unit in the aircraft to generate ground speed signals, said control means responsive to said ground speed signals.

A system for prerotating an aircraft's landing gear wheel prior to landing, comprising:

• at least one landing gear wheel attached to the aircraft by a support;
• non-contact means for rotating said wheel at revolutional speeds while the aircraft is airborn, wherein said means for rotating is in close proximity to said wheel and is not in contact with said wheel to allow said wheel to rotate independently from said means for rotating;
• and
• means for measuring said revolutional speeds of said wheel comprising photoreflector on said wheel and a non-contact photosensor mounted apart from said wheel to generate an r.p.m. signal based on sensing the passing of said photoreflector;
• and
• control means including a microprocessor operable to read r.p.m. signals from said non-contact photosensor and wherein said microprocessor is programmed to send a control signal to said means for rotating said wheel to increase and decrease rotational speed of the wheel responsive to said r.p.m. signal wherein upon an excessively high r.p.m. signal said control signal causes a decrease in rotational speed of the wheel, and inversely upon an excessively low r.p.m. signal said control signal causes an increase in rotational speed of the wheel.

A fully automatic closed-loop control system for prerotating the landing gear wheels of an aircraft during approach and landing, retrofitable upon existing and operational aircraft, comprising:

• means for causing wheel assembly rotation, wherein wheel rotation is induced solely by force of high velocity air resistance experienced by the aircraft moving fast through the air, such high velocity air being controllably ducted and directed through variable air-intake actuating mechanisms against blades of impellers affixed to each wheel assembly;
• means for continuously measuring and transmitting the instantaneous true ground speed of the aircraft throughout approach and landing;
• means for independently and continuously sensing and transmitting the instantaneous rotational speed of each landing wheel assembly;
• means for independently and continuously controlling the amount of high-velocity air directed against each impeller of each landing wheel assembly, thereby independently increasing, sustaining or decreasing the instantaneous rotational velocity of each wheel assembly to achieve and maintain a peripheral velocity of each tire synchronous with instantaneous ground speed upon wheel touch-down;
• means for processing electrical signals from said means for transmitting ground speed and from said means for transmitting rotational speed of each landing wheel assembly, said means for processing and distributing appropriate electrical power of correct polarity and amplitude to all air-intake actuating mechanisms to each operate independently in true closed-loop servo mode.