Naked Emperor?

An interesting comment from someone who claims to work on the program, over at Space Politics (it's the sixteenth one), in response to the usual idiocy that everything is fine with ESAS, and that we all have to get behind it, and there are no other choices:

Your interpretation of published Ares I status is overly optimistic to an extreme. For instance, the J-2X ignition tests to which you refer has been done at the igniter level, a far cry from an actual engine test. The J-2X exists only on paper, and still very much at the powerpoint level.

The Ares I-X is also merely a stunt and represents no true progress to an actual flight configuration. It's what we in the business refer to as an "Admiral's Test," looks impressive to the uninformed, but adds no value to the final product.

You'll find that many of us Ares I naysayers actually work on or have involvement with the project. Ask the troops at MSFC and you'll get a completely different story than what you're getting through the NASA propaganda machine.

A lot of us are concerned with what kind of reputation we'll be left with when Griffin leaves and this whole Ares I/ESAS debacle is exposed.

That certainly rings true to me, based on other emails I get from program insiders.

Meanwhile, over at NASA Space Flight, there's a description of proposed solutions to the Ares vibration issue. The first one is the most interesting kludgesolution:

The anti-Thrust Oscillation RCS would be a totally new system, located on the aft skirt of the Ares I booster. Known as Active Pulse Thrusters (APT), documentation shows this system to hold the potential of reducing Thrust Oscillation by around 10 times that which is currently expected.

'Active Pulse Thrusters (RCS TO Damper): First Stage carries most of the design changes (Orion Service Module tanks change required),' noted associated documentation on this concept. 'Could provide 10X reduction in TO. Relatively mature thruster design. Self contained. Relatively mature control system.'

However, it would - as with most of the mitigation options - hold a mass impact on the vehicle, something Ares I has been struggling with since its early design cycles.

'Performance and aft skirt design challenge: (around) 500 lbm (pounds mass) payload impact. Trade required for separation and booster deceleration. Add failure modes. Must survive aft skirt environments.'

The system consists of four pods, located around the aft skirt on the Ares I First Stage. Early graphics of a system - that are bound to mature if accepted as the way forward - show each pod will have a fuel tank, an oxidizer tank, a pressurant tank, and seven thrusters.

The downside of this concept - which is a completely separate system than the roll control system on the interstage - is the addition of failure modes, which would hit Ares I's LOC/M (Loss of Crew/Mission) numbers.

Also on the downside, the concept is a retro thrusting system (negative thrusting) - which would impact on Ares I's performance figures.

OK, if I understand this correctly, this is what I would call the "Bose headphone" approach. Apparently, the plan is to actually fire thrusters in a direction opposite to the main thrust, at a frequency and phase to actually cancel out the vibration of the SRM. The description of the downside of this solution is a little dry, to me. They are introducing a new, complicated, expensive-to-develop-and-test system into the vehicle, which will add weight and (probably weird) potential failure modes, and reduce the net thrust of the vehicle, thus reducing its payload performance, which already has essentially no margin.

Great.

Next? Isolation mounts:

'May reduce payload by 1000 lbm. Reduces lateral stiffness unless mitigated in the design. Adds failure modes. Changes system modes for loads and control.'

"...unless mitigated in the design." There is an implicit assumption in that statement that such a mitigation is possible, but it may not be. I suspect that it doesn't just reduce lateral stiffness, but may also reduce stiffness in bending, which means more potential problems as the upper stage wiggles back and forth on top of the SRB, adding to the joy of the ride for the crew, and further complicating the control system's job, in all three axes.

They're right--this one is unlikely to survive the trade study.

Even the third, favored option is a kludge, which "consists of rails and springs under the top plate of the parachute platform on the First Stage. The active system would require a control system and associated battery power supply - all located under the aeroshell that houses the drogue parachute."

"The passive system has a rail attachment on the forward skirt extension of the First Stage providing lateral support. Damping would be provided by springs attached through the ancillary ring."

Rube Goldberg, call your office.

I've probably used this Einstein quote already recently, but it continues to apply: a clever man solves a problem--a wise man avoids it. This is all the result of the strange decision to use a Shuttle SRB as a first stage. That was not a necessary choice, and a good trade study (as opposed to the sixty-day exercise) would have identified these problems up front, and considered them in the trade. Anyone want to bet that it did?