barit1:
And so when a PW4000 runs up to max on a terrestrial test bed, it is actually creating ~70,000 thrust HP? Is that what we surmise?
No. THP has to do with
aircraft performance. When it's on a testbed, you wouldn't be analyzing THP. The engine would be producing thrust and you could compute how efficient the engine is in making thrust (ie: accelerating air).
EDIT: However, if you were to apply the concept of THP to the testbed scenario, the THP would be zero because the testbed/engine wouldn't be moving.