Multiple Rolling Tire Sinkage and Drag Interaction Effects

A study was made of the influence of adjacent loaded areas on the performance of rolling aircraft tires on soil runways. These tire/soil interaction effects which occur in multiple tire landing gears were evaluated based on sinkage and drag. The total study consisted of four parts. Three of the parts have been completed. The fourth part, which is an experimental effort, is still in progress. The first part consisted of an evaluation of existing full scale field test data from aircraft or test carts operating with multiple tire configurations. The second part was a Dual Plate Vertical Load Test Program which yielded sinkage interaction effects from single and dual plate load tests in sand and clay. An analytical study was made in the third part using a lumped parameter iteration technique together with an elastic-plastic soil model for studying adjacent load interaction effects. The results show that definite benefits in terms of rolling drag reduction can be gained by proper use and spacing of dual and tandem tires when operating on sand and clay type soils.