test bed 
noun
A piece of equipment used for testing new machinery, especially aircraft engines: fan blades were subjected to fatigue tests on laboratory test beds figurative a test bed for new technology...
- It has its engines mounted above the wings, but for the moment it is intended primarily as a test bed for the jet engines and will not be offered for sale.
- Since the plane was a test bed, the engine configuration was changed to a tractor position and Bellande found the performance equally as good as the pusher configuration.
- In 1940, the prototype was sold to Pratt & Whitney for operation as an engine test bed.
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