Saturday, August 20, 2011

The Evening Wrap, 8/20

I want to return to the flyable rocket proposition, if I may.

The Shuttle system seemed to me to be an incomplete design. If the idea was resusability and rapid turnaround, then it failed. But there were a number of accomplishments. Being able to return the orbiter was one and the recovery of the solid rocket boosters (SRB) was another. A third possibility was to reuse the external tank while still in orbit, but this never materialized.

It failed because, even though the orbiter returned to the launch site, it wasn't a fast turnaround. The same was true of the SRBs. And no effort was made to return the external tank or reuse it in space at all. This all came up short, but why? Could the Shuttle and the SRBs be processed faster? Could there have been a way to use the external tanks? Or was it just a flawed design, which needed to be improved upon?

I think it was the latter. The Shuttle was called upon to do too many things in order to satisfy too many people. Its primary purpose was lost in all this and was shoved back into a lower level of priority. It had to please Congressional districts, who wanted a piece of the business. This led to a SRB design which required that SRB's be sent from Utah to Florida- not very convenient. It led to the Challenger disaster because of the segmented rocket boosters failed to seal off hot gases which led to the disaster. Another factor was the Shuttle's main engines were run greater than capacity, which caused greater turnaround time, as well. Furthermore, it was called upon to deliver a lot of cargo, which required a much bigger orbiter. Too many objectives had to be met- it needed to be simplified and less ambitious.

Now, we can ask, what if? What if the orbiter was smaller and used boosters made and serviced in Florida, near the launch site? What if its only mission was to deliver small amounts of cargo unmanned, or just a few astronauts? The orbiter weighed over 100 tons. Could this have been improved upon? Given that 95% of what launches is fuel and oxidizer, a much smaller shuttle would have made a much smaller launch system feasible. One half of the size of the shuttle would have halved the size of the external tanks and SRB's. Or, you could have kept the size of the launch system the same, while improving the reusability of the remaining part that wasn't reused- the external tank.

If you have added flight capability to the external tank, or protective heat shield with some thrusters and parachutes, then you may have save the external tanks. But then, where do you splash down? But if the tanks were smaller, might it have been possible to make them flyable? On the other hand, if the tanks were small enough, might they have fit on top of a plane and sent back to Florida?

In other words, could have system been devised which would allow all the pieces to be collected, serviced, and reused in a shorter time frame? It seems like a little more thought may have made that possible.

Well, that's all for now. Thanks for coming by and have a great evening.

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