Message posted by Mark Lincoln on July 30, 2011 at 7:47:14 PST:

The HALE-D is a stratospheric super-pressure airship. This means that the aircraft is fully inflated at take-off and it will maintain a higher than exterior pressure at all times.

Super-pressure ultra-high altitude balloons have been in use for almost a half-century and some have circled the earth many times before descending.

While information is scarce it appears that the HALE-D was not able to ascend beyond the 36,000 foot range and thus was caught in winds it could not fly against. It is very probable a failure of the envelop or valve system was involved. The only 'good' landing down-wind place for it would have been Lakehurst, NJ or Weeksville, NC which have hangers which could hold it without deflation. Reaching either was probably unlikely due to winds or gas/pressure loss.

I doubt the envelope would have been reusable under any circumstance (this is the norm for extremely high-altitude balloons which require extremely light construction). I think they did what they could and the essential - and expensive, parts - have probably survived the landing. (Who knows what damage was done upon recovery?)

The mission for HALE-D is to act as a radio/data relay orbiting an operational area for a long period of time at low relative cost.

It has taken over 70 years for the image of the Hindenburg to subside and the possibilities of airships to once again be investigated. The advantages of operation with low power and long duration remain. The problems of ground handling and low speed also remain. The Defense Department did away with it's institutional knowledge and experience in operating airships almost 50 years ago.

The contractor has little such experience, though the P-791 seems to have been a success.

This is a case where a steep learning curve must be expected and a certain failure rate inevitable.

I think they did well based upon initial reports.

In Reply to: Re: HALE-D failure posted by Mark on July 28, 2011 at 20:16:16 PST:

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