Message posted by Mark Lincoln on August 13, 2011 at 22:13:11 PST:

Peter, the first mission showed us that hypersonic vehicles of extremely high finesse ratio are more prone to roll/yaw coupling than predicted. It also showed that the transition between laminar and turbulent flow at hypersonic speeds was inadequately understood. Congratulations, we have established that inertia coupling at hypersonic speeds is even more treacherous than at supersonic speeds.

The second flight proved we had not learned enough from the first.

Data reduction from telemetry of the second flight MIGHT prove useful in resolving the discrepancy.

One thing that this whole program HAS proved so far is that we don't need to pay the cost of putting some guy in a cockpit to learn how to fail as we once did.

Good, easier on the meatware and the budget.

As an experiment in hypersonic flight outside the realm necessary for successful re-entry of vehicles as diverse as the Space Shuttle and a simple RV it is interesting. That maneuvering re-entry vehicles had been successfully explored as long ago as the 1960s only shows the extremity of control sought in the current program.

I have a life-long love of aviation history, aerospace, aerodynamics, structures, systems and technology. I was astounded that I found Failure Mode And Effects Analysis more fascinating than aerodynamics or structures. I am watching this program with avid interest and not disdain.

Whether the dream of having an invincible method of striking a maneuvering target on the other side of the world with nuclear weapons is one that might result in a viable or useful weapon is extremely unlikely if not laughable.

DARPA's most extraordinary and revolutionary - indeed world changing - development was DARPA Net. Father of Internet.

One was an astounding development, while HTV-2 is an interesting exploration of extreme hypersonic aerodynamics.

p.s. What is astounding about being able to take GPS readings in hypersonic flight? It is not as if we had not been doing it for years.

p.p.s. what is the relationship between the wavelength of the GPS transmissions and the size and movement of the HTV-2?

In Reply to: Re: DARPA - we have a problem ... posted by Peter Merlin on August 13, 2011 at 0:04:43 PST:

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