3
$\begingroup$

As I'm reading "Ignition!" I'm finding one point baffling: vapor pressure being such a big deal. Outgassing of both fuels and oxidizers would cause dangerous pressure build-up. The book describes the hair-raising stress of handling materials that release oxygen. The utter horror of watching technicians estimate the pressure by measuring barrel bulging. The stringent requirement for periodic manual venting. Abandoning one promising line of research purely due to unacceptable vapor pressure.

A check valve is a really simple, cheap, small device that would neatly protect the contents of the container from environment, while allowing whatever accumulates in the container to vent once the pressure inside rises above a preset value. Even equipping individual barrels with these would cost pennies. Did no-one think of that, or is there some other reason making this impossible or impractical to such a degree that vapor pressure would become an insurmountable problem?

$\endgroup$
  • 3
    $\begingroup$ aka "relief valve" $\endgroup$ – Organic Marble Jan 12 '17 at 15:30
  • 3
    $\begingroup$ I'm not sure I like the idea of tanks filled with hypergolics venting automatically, in a potentially unknown environment (could be an atmosphere, could be a vacuum, might even be during reentry or orbital maneuvering)... I don't know to what extent this entered into the considerations, but it would definitely be among the first considerations on my mind if I considered adding something like that to a design! $\endgroup$ – user Jan 12 '17 at 15:50
  • 2
    $\begingroup$ All the manned US ships had pressure relief valves, usually on the helium for the rcs and often many other places too. $\endgroup$ – Innovine Jan 12 '17 at 17:15
  • 2
    $\begingroup$ @Michael kjörling I'm not sure I like the ioea of the hypergolic tanks not venting, either, and possibly bursting in an uncontrolled manner. I guess the controlled venting can at least be directed so as to not trigger problems with other tanks, plumbing and whatnot. $\endgroup$ – Innovine Jan 12 '17 at 17:17
  • 1
    $\begingroup$ @MichaelKjörling: this nearly universally applied to long-term storage - fuel for missiles. In many cases the products were fairly benign too - release of $O_2$ appeared most hated in particular, even though in case of constant venting the concentrations would be entirely harmless. $\endgroup$ – SF. Jan 12 '17 at 18:38
3
$\begingroup$

It's worth remembering a lot of the research John D. Clarke recalls in Ignition! was not primarily being conducted with the requirements of civilian space flight in mind.

The military were interested in propellants that would allow munitions to be fuelled in the factory, then stored indefinitely, but ready for immediate use.

Setting aside any risk of toxicity or flammability resulting from the vented propellants, any losses through check valves could mean that the performance of any rocket could vary over a wide range.

| improve this answer | |
$\endgroup$
  • $\begingroup$ That was desirable, but it seems filling the tanks "in field conditions" was acceptable as long as the substances weren't too dangerous to handle. $\endgroup$ – SF. Jan 12 '17 at 22:32
  • $\begingroup$ I'd say it was acceptable, in the absence of a better solution, Ignition! is the story of the search for the better solution (setting aside the lack of focus on solid fuels). The search for propellants with a combination of both good performance, storage, and handling characteristics is a repeated theme throughout the book. $\endgroup$ – jaketmp Jan 13 '17 at 16:01
  • $\begingroup$ Yep, "handling characteristics". It still cracks me up, that a whole very promising line of research was abandoned because the substances happened to be so unbearably stinky the staff rebelled and dumped the synthesized stock into the sea despite all other characteristics being well within acceptable standards. $\endgroup$ – SF. Jan 13 '17 at 19:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.