Paper Number 4.1
Calculation of Dynamic Tire Forces
From Aircraft Instrumentation Data
Gary E. McKay
Cessna Aircraft Company
Email: gmckay@cessna.textron.com
Voice: (316) 517-8841
When evaluating aircraft brake control system
performance, it is difficult to overstate the importance of understanding
dynamic tire forces – especially those related to tire friction behavior. As important as they are, however, these dynamic
tire forces cannot be easily or reliably measured. To fill this need, an analytical approach has
been developed to determine instantaneous tire forces during aircraft landing,
braking and taxi operations.
The approach involves using aircraft instrumentation
data to determine forces (other than tire forces), moments, and accelerations
acting on the aircraft. Inserting these
values into the aircraft’s six degree-of-freedom equations-of-motion allows
solution for the tire forces.
While there are significant challenges
associated with this approach, results to date have exceeded expectations in
terms of fidelity, consistency, and data scatter. The results show excellent correlation to
tests conducted in a tire test laboratory.
And, while the results generally follow accepted tire friction theories,
there are noteworthy differences.