Jim Bennett says that it's not always as obvious at the time what should be done, as it is later to the Monday-morning quarterbacks. He compares the Titanic to the World Trade Center. And to Chamberlain's appeasement of Hitler in 1938.

One example he points out is relevant to space (you knew I was going to talk about how this is relevant to space, didn't you?)

Today we ask, "How could Titanic not have enough lifeboats for everybody?" But at the time, it was assumed that lifeboats were only usable in a minority of scenarios, and in most of those scenarios the boats would be used to evacuate passengers from a slowly-sinking ship to another ship, making multiple trips. The general assumption was that it was more productive to concentrate on making the ship as robust as possible. Similarly today we do not design airliners with military-style ejection pods, like those used on bombers, but rather concentrate on making the aircraft as robust as possible.

And similarly, we didn't design the Shuttle for ejection--the design goal was to make such an eventuality unnecessary, because it was unaffordable to put in that capability. It would have added a lot of extra weight to the vehicle, sacrificing payload, and it would have had a dramatic impact on functionality of the system as planned.

The problem with that philosophy was that they didn't just save money on the crew-escape system--they also scrimped on the reliability, by using multi-segment solids, instead of liquid boosters, and in not providing adequate testing of the system, because it was too expensive to fly, as designed.

But the lesson is not that manned space transports must have ejection seats--it's that we need to truly design them to not require them, just as we do airliners.

Jim Bennett: 'Today we ask, "How could Titanic not have enough lifeboats for everybody?" ... The general assumption was that it was more productive to concentrate on making the ship as robust as possible. '

But that's not what was happening, according to _The Night Lives On_ by Walter Lord:
'Far from being a triumph of safe construction, or the best that could be done with the technology available, the Titanic was the product of a trend the other way, a trend that for 50 years had seen one safety feature after another sacrificed for competitive reasons. ...
[double hull, longitudinal watertight bulkheads, watertight deck above the bulkheads]
... When the "unsinkable" Titanic was completed in 1912, she matched the Great Eastern in only one respect: she, too, had 15 transverse watertight bulkheads.'

If I remember correctly, Von Braun's concept for the orbiter featured in the Colliers articles back in the early fifties had ejection seats/pods for the crew and passengers. I loved that series, it weaned me off Dr.Dolittle. Von Braun figured the whole shebang would run $ billion including the fancy space station.

That's $4 billion U.S. at the time, and yes the system is a little buggy, at least in Netscape...Aloha, Hunt

It might pay to heed the engineers sometimes; the O-ring was a known weak point, the engineering types strongly recommended the flight be postponed at least two days, but the go-ahead was political.

While I am at it, and against my judgement of Madison Avenue, I wish NASA would get some decent PR types and publicists. There must be some who are in favor of expanding our resources rather than hunkering down with the Earth-firsters waiting for the long night...

One of these days, someone will write a truly definitive book about the decisions that went into the shuttle design. Were they "scrimping" when they chose solids over a liquid booster design? Surely, liquids would cost more on a per flight basis but the liquid engines (F-1s) were already built and proven. The manufacturing tooling existed to make more. The workers were trained. It was just a case of ordering more units. The solids had to be designed, built and proven before flight. This was all "up front" money. The rumor I've heard is that the decision to use solids originated in the fact that certain Senators from Utah were essential to getting the Shuttle program off the ground in the first place. The decisions for solids centered on the number of jobs provided near Salt Lake City. This is all hearsay of course.

One reason for choosing solids was because it was thought they would be easier to recover by parachute than liquids. Solid booster casings are (generally) thicker than liquid fuel tanks, which it was thought would help them survive an ocean landing. Plus there would be problems in reusing an engine that was dunked in salt water...
The shuttle was a 'make work' program, important contracts were given to firms in key districts, so what you said about utah sound about right

Liquids would cost *less* than solids on a per-flight basis. Solids were chosen to save money in development costs. And as for them being recovered by parachute, liquid boosters would ideally have been flyback, but again, this was not an available option under the annual development budget constraint.

Solids weren't chosen for political reasons, but the contractor for them (Thiokol) probably was. Jim Fletcher was from Utah, after all. And because they had to be shipped from Utah, they had to be multi-segment, which was the cause of the Challenger disaster.

I should add that, while it's not a published book, Scott Pace's master's thesis at MIT is considered to be the definitive work on that subject.

Reusable...hmmm....That's another datapoint I'd like addressed about the early Shuttle program. Who made the decision for a reusable booster, and using what data? Every so often I hear stories that with the flight rate at four to six sorties a year, it would be cheaper to just throw the solids away than go through the hassle of going out getting the floaters, bringing it back to the cape, washing out the detritus, shipping it back to Utah etc etc. My guess is that somebody said that it would fly 60 times a year starting in 1980 and that they needed a reusable booster. It thus becomes circular reasoning. We need reusability to get to 60 missions a year. With 60 flights a year, we can only do that with reusable boosters. The development cost of the solid was less than a liquid booster if it was assumed a priori that reusability was the best. I have never seen good data saying that was the case, reusability was just plucked from thin air. A throwaway liquid F-1 powered booster would have been cheaper than the solids. The engines were already flying. One would have to design and then integrate tanks and engines. But that didn't employ anybody in Utah did it?

I'm not aware of any expendable liquid stage that's ever been cheaper than a solid of equivalent thrust.

The decision to go with solids was based on minimizing development cost. Almost all decisions in the Shuttle program were. I don't believe that expendable liquids were ever considered, primarily because they were perceived to be more costly per flight than refurbishable solids.

And it's true that at the current flight rate, recovering and refurbishing the solids almost makes no economic sense, but at the originally planned flight rates (still twenty-four a year as recently as the mid-80s) it did.

I guess I would have to see the numbers. When you say the solid is "cheaper" than the liquid of equivalent thrust, what does this mean? The solid casing masses around 180,000 pounds. A RP/LOX tank equivalent would mass 40,000 to 50,000 pounds. Since Aerospace pricing is a function of weight, I would surmise that the liquid would win. If you say that the solid is cheaper than the liquid if both were starting from the same point, I would agree. However, they weren't starting from the same point. The F-1s were flight hardware, the SBM had to be developed, and they were developed with a fatal flaw as we found out. The VAB had to be modified to handle millions of pounds of propellant. The crawler had to be modified to carry heavier loads. The pad had to be modified to take the solid corrosive exhaust. Was the Shuttle designated to have solids because of minimum dev costs? Yes if one accepts the boundary condition of a reusable booster. The solids that were presented as part of the final design had blow out ports for inflight shut down. This feature was dropped as too heavy once the program got started, to the detriment of safety. As a side note, there were four initial applicants for the EELV program, Lockheed, McD, Boeing, and Alliant. Only Alliant introduced a mostly solid design. The solid was the first design dropped by the Air Force as not meeting requirements.

Aerospace costing (not pricing) is not (just) a matter of weight. There are other factors (such as complexity, which solids score low on, and liquids high).

Solids are cheaper than liquids, when they're being thrown away. I'm not aware of any counterexamples.

When they're not being thrown away, liquids win, if the flight rate is sufficiently high, but the operational costs were not a significant factor in Shuttle trade studies.

Sorry.

Call Lockmart and "Dial a Rocket" its that easy :)

You say that solids are cheaper than liquids because of complexity. I agree if both are starting from zero. The shuttle SRM was absolutely new at program start. A facility had to be built in Utah, testing done etc etc. The complexity in a liquid rocket is mostly in the engine. In 1972 the F-1 was flight hardware. All the non-recurring costs had already been spent. The tooling was up in place, the factory running, the employees trained. I have a hard time believing--using 1972 as a starting point--that the solid would be slam dunk especially when the safety factor is tied in. I return to my original thesis that the solid decision was essentially political. I will however await for that definitive book on the shuttle.

You continue to miss the point. An expendable liquid booster, even if it uses an existing engine, was estimated to cost more per flight than a refurbishable solid, so that option was thrown out immediately. Liquids only made sense, in their minds, in the context of a reusable (probably flyback) booster. They didn't have the money to develop it, so they went with the refurbishable solid.

The point you're missing is that the initial shuttle configurators chose to pay a huge non-recurring amount up front in the solid development justifying this initial expense on a reduced per flight cost. But was this justified on 60 or 24 flights per year? And where did that flight rate come from? Was it pulled from the air? What I am coming to conclude is that that the configurators wanted the solids for political reasons and created all kinds of initial conditions to justify their decision. That is,in my mind, the shuttle's real story. I've been on enough trade studies to witness some manager squirming when he sees the answer as not to his boss's liking. Then "let's change this this and this." Viola! Reusable solids. So let me ask this. If they knew then what they know now about safety, pollution, and flight rate who they have chosen solids?

"If they knew then what they know now about safety, pollution, and flight rate who they have chosen solids?"

Almost certainly not. But they didn't know it then.

There is no evidence in the historical record (of which I'm aware) that the solid decision itself was driven by politics, other than the politics of scarce resources. The decision to choose Morton Thiokol may have been political, but not the decision to use the solids themselves.

Somewhere someone knows about that decision to use the solids and the conditions that went into making it. That will be a very interesting story when and if it comes out.

To address Bill Woods' quote from Walter Lord: Lord made a rather unsupported claim of decline in maritime safety between 1850 and 1912. Using the Great Eastern as a benchmark is particularly disingenuous, since it had many features that were not incorporated into subsequent ships for decades; it was more like a prototype that never produced a line of production models. What Lord needs to produce to substantiate his claim, and doesn't, is evidence that passenger fatalities per passenger-mile sailed increased during that period. All indications are that passenger deaths per passenger-mile declined sharply, both due to more robust ship construction and to better on-board sanitation, since shipboard disease was the real killer in previous eras. For instance check out Drew Keeling discussion at http://migration.ucdavis.edu/cmpr/oct98/Keeling.html

"Skepticism is not unwarranted here, but certainly safety was a concern to migrants, and sea disasters were much more common on the much smaller ships of the sailing and early steam eras. It is
difficult to explain the confluence of risks taken in the design and operation of the Titanic, without reference to widely-held beliefs of "unsinkability".
The attenuated attention to risk exposed by the Titanic's demise,underscores the degree to which technical improvements over the course of six decades of steamline service had transformed the Atlantic crossing. From an odyssey undertaken by intrepid pioneers or refugees in flight, transatlantic migration had become something more like the seasonal labor flows or rural-to-urban movements which grew with it and overlapped it. "

Why is UPI printing an Opinion?