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Does Obama Have a Problem At NASA?
MarkWhittington writes "Has NASA become a problem for the Obama transition? If one believes a recent story in the Orlando Sentinel, the transition team at NASA, led by former NASA Associate Administrator Lori Garver, is running into some bureaucratic obstruction." Specifically, according to this article NASA Administrator Michael Griffin made calls to aerospace industry executives asking them to stonewall if asked about benefits to be gained by canceling the current US efforts to revisit the moon; we mentioned last month that cutting Aries and Orion is apparently an idea under strong consideration by the Obama transition team.
For some reason the submission goes to a site that mentions the original articles appeared at the Orlando sentinel, but doesn't link to the articles. So here they are:
December 11: NASA chief Griffin bucks Obama's transition team
and
December 12: NASA chief insists he's cooperating with Obama's team
From the article: Michael Griffin, noting that no one on Lori Garver's team has any engineering expertise, suggested that Garver was "not qualified" to judge the Constellation program. Garver will not comment about the conversation, but has hinted that there will be a new administrator chosen at NASA shortly and that there will be change to NASA policy."
Toeing. Not towing. Much less work.
Watch this Heartland Institute video
IANAAE (I am not an aerospace engineer) but to me, Ares looks silly. Solid rocket boosters do not burn smoothly, they have a big problem with thrust oscillation. The designers actually worry that these vibrations will incapacitate or kill the crew.
To quote a real expert...also known as Resonant Burning - described as vortices that shed within the solid rocket motors during combustion due to the shearing of internal flow at propellant discontinuities - the issue relates to when the frequency of thrust oscillations is coincident with the acoustic modes of the motor cavity.
Solids work fine when grouped together with liquid stages, but a single solid booster just seems wrong.
IAAAE (I am an aerospace engineer) and Ares looks silly. Solid rockets should never be used for manned vehicles. The capsule idea is the way to go but the LV is a bad choice IMHO.
As YAAE, I think it looks silly for several reasons. The first and most important one: you can't actually test fire the engine you're going to trust your life to! You can inspect it, and you can test the process, but you can't test the actual article. Furthermore, the propellant grain is susceptible to handling damage and manufacturing defects, so there is reason to want to test it. There are cases where solids in proximity to humans are reasonable -- small solid motors for ballistic parachutes, for example. Or signal flares. In those cases, you can reasonably test two or three orders of magnitude more devices than will be tested for Ares (mostly because they're smaller). The other cases where solids are better is where readily storable propellants are required, like for most missiles. That doesn't apply here. (There are plenty of other reasons as well, but I won't bother going into them.)
The mistake that leads to thinking solids are a good choice is comparing them to the SSME and other engines like it as if that was the only alternative. It's not. The best design to compare it to is probably LOX/Kerosene running at a modest chamber pressure, with a pump feed (gas generator cycle) where the pump and its drive system are heavier than they could be, but simpler in design and with more margin (and hence more reliable and cheaper). It doesn't need to be a turbopump -- piston machinery works too. For a large system, though, the turbopump is probably enough lighter to be better, but it should really have more resemblance to industrial turbomachinery than conventional rocket machinery. Yes, that won't hit the maximum possible Isp or mass ratio for the stage. But that isn't as important on a first stage (or really, anywhere you'd consider using a large solid -- even the low-performance LOX/Kero rocket will beat the solid). What is important are things like design cost, manufacturing cost, and reliability.