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I'm Shocked

Orion, already overweight, just got heavier:

"Preliminary estimates show that if this 30-40% [turbulence] heating augmentation heating is applied to the aerothermodynamic database the heat shield mass may increase up to 20%," says an internal NASA report obtained by Flightglobal.

I wonder if, instead of using an ablator, a tile system would be lighter? It would be more maintenance intensive (particularly with water landings), but it wouldn't be as bad as the Shuttle, because many of the tiles would be symmetrical and more mass producible. We were never really allowed to do this trade in Phase B at Northrop Grumman--NASA just told us they were going to supply the TPS.

I'm actually quite surprised at this--I would have thought that they'd have modeling an ablative shield down to a science by now. Apollo was way overdesigned, because they didn't have any experience or good analytical tools to indicate how much shielding they needed. If you look at the heat shield on an Apollo capsule, you can see that it is just slightly charred, with most of it unburned; it could have done a couple more missions without refurbishment or replacement. But based on that experience, we should have been able to predict the optimal weight of an ablator designed to come back from the moon pretty well, and years ago. How did this come up just before PDR?

Anyway, now they have unexpected weight growth in the program at the same time that they have weight and performance problems with the Ares 1. And apparently there are budget problems at LM, as well, if this report is true:

The ORION contractor is overrunning. The minions are out of money. Where can 20-30% more funds be dredged up to cover this miscarriage? You guessed it...the little man.

The minions have let the contractor off the hook for meeting its small business obligations this year. The same obligations that were bid as part of the winning proposal, ostensibly offering a better package than the opposing team, are now null and void. As a result, some of those little companies will start disappearing, lacking jobs and income.

They seem to be achieving the trifecta--failing on performance, schedule and budget. It's a program manager's nightmare.

[Update a few minutes later]

Some further thoughts over at Gravity Loss:

What will the payload landed on the moon be? What propellants are used? What is the Altair's or Orion's mass? And work back from there to TLI mass and ultimately to launch from Earth, all with generous margins. And it has seemed that a certain cycle has formed. First a solution on Ares I is based on some logic linking it to Shuttle hardware, infrastructure or Ares V with common elements, which should save a lot of money and time and keep the workforce etc etc. Somewhat later, rumors about a severe performance shortfall on either launcher start circulating. Then after a while NASA announces a new configuration where the commonality is disrupted. And again forward we go.

Unfortunately, the concepts seemed to be driven more by politics than engineering. That was often the case in Apollo, too. The Manned Spaceflight Center could have remained at Langley, but there were political reasons to move it to Texas. Marshall didn't have to be in Huntsville--they could have moved the rocket team at Redstone to somewhere else (e.g., the Cape, whose location really was driven by geography and not politics). But there were two differences in Apollo. It had essentially unlimited budget, and its success was politically important. Neither applies to the VSE, yet NASA, by Mike Griffin's own admission when he announced the architecture, not only chose to do Apollo over again, but to do it "on steroids."


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Habitat Hermit wrote:

Hmm weren't they using a (likely improved upon) version of PICA for the heatshield? I shouldn't really say anything not being an engineer etc. but mustn't something be horribly horribly wrong for it to be insufficient?

Leland wrote:

One heatshield design option is PICA and the other Avcoat.

Interested Observer wrote:

A little birdie said that the reason this debacle happened is that they were desperate to save weight, heard that the Apollo heat shield was 50% over specced, and so zap! saved weight by merely slicing off that weight from the spreadsheet.

Such is how design decisions are made these days.

Kelly Starks wrote:

>> I wonder if, instead of using an ablator, a tile system would be lighter?
>> It would be more maintenance intensive (particularly with water landings), ...

Orions spec'ed to be a single use capsule now, so this isn't an issue.

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About this Entry

This page contains a single entry by Rand Simberg published on July 14, 2008 1:28 PM.

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