Unsurprisingly the idea was quickly abandoned.the devils always in the detail. Upon investigation it was discovered a local turbulent airflow between the fuselage and wheel would cause at least one to spin in the wrong direction. When the trials aircraft took off the pilot braked the wheels to a stop in flight, released the brakes and watched to his horror one wheel spin up in the correct direction and the other spin up in the wrong direction! He made several attempts to see if he could get both spinning in the same direction but failed, so did a very slow descent rate landing with an initial skip to get all the wheels spinning correctly. Hence they modified a couple of tyres with rubber cups to provide an urge to spin up. The MP asked questions to the Defence Ministry so the RAE were duly tasked to give it a go. or it jams ?įrom memory there’s a reference to a trial conducted by RAE on Tornado where a chap wrote to his MP demanding that this obvious cost saving be investigated. In summary, most of the tyre wear comes from braking + turning at MTOW, a spin up motor torque/power requirements are surprisingly high (it includes a few sums), cups/vanes will never match the landing speed/take way too long and if such a system really was used to lower touch down loads, what does the pilot do on the day the system doesn’t work. The aircraft landing systems industry wide standards committee, the SAE A5 has seen pre spinning suggested so many times they’ve produced a standard response which from memory is AS5400 - This is factually based, professionally referenced and details the rationale for not doing it. Pre spinning wheels is regularly suggested but has never been taken up to any significant degree ( I never knew about the Cutlass NLG. If you wish to spring the dollars an SAE report here, From these considerations it would appear that prerotation should have little effect on tire life. Since the only source of tire wear in the impact-basin tests is the wheel spin-up process, the much larger rate of wear in the flight landings appears to be due to sources other than wheel spin-up, perhaps braking and turning conditions. The tires on an airplane having the same type of landing gear were worn out, however, in a substantially smaller number of landings under much less severe impact conditions. On the other hand, no appreciable amount of tire wear was evident in the impact-basin tests, even though the program involved some 450 simulated landings without prerotation, covering a range of vertical velocities up to 9.6 feet per second and initial skidding velocities up to 273 feet per second. It would seem that prerotation should greatly decrease tire wear. From the results of the many tests which were made in the basic study of wheel spin-up drag loads, certain inferences may be drawn regarding the probable effects of prerotation on tire wear.
0 Comments
Leave a Reply. |