Does anyone know the critical altitude for the (long-winged) H-1 Racer Howard Hughes flew to set his record transcontinental flight? I'm having trouble finding a definitive answer online. I've seen numbers from 5000 ft to nearly 30,000. It's confusing. 5000 seems very low for a flight where Hughes would have to fly over mountains and above weather, but 30,000 seems more an end-of-WWII number. I would appreciate any and all help on this subject. Many thanks in advance.
JAMES
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