Rockets- Hot Staging vs. Drifting.

[rdfox]

For the record, lower-stage explosions *do* occur with hot staging at times; one example is the launch of Gemini 10, where the first stage oxidizer tank ruptured just after staging, because thrust impingement on it from the second stage caused it to overpressurize and burst. However, it's not really that much of a worry.

After all, even with the violence of a tank bursting, the debris wouldn't reach the upper stage--it's already overpressurizing due to thrust impingement from the upper stage, and any of the debris that IS driven upward by the tank failure would be getting blown straight into the exhaust of the upper stage engine, which would pretty much instantly stop it and send it back down away from the upper stage. Any that has enough horizontal velocity to not get blown back away with the exhaust would be flying at an angle that doesn't pose a threat to the upper stage.

[Dkmdlb]

According to the source that you cited, "hypergolic UDMH [was used] as the fuel and a saturated solution of dinitrogen tetroxide in nitric acid [was used] as the oxidizer." None of these chemicals actually have fluorine in them, let alone ClF3. (Unsymmetrical dimethyl hydrazine, or UDMH, is H2NN(CNH3)2, containing only hydrogen, carbon and nitrogen.)

For some reason I just assumed that was the incident in question and didn't really check my facts. Good catch.

[Kryten]

Nobody has ever actually built a ClF3 rocket, never mind launched one. The closest anyone got was a soviet NH3/F upper stage project, and that was cancelled after a few ground tests.

[mdatspace]

Nobody has ever actually built a ClF3 rocket, never mind launched one. The closest anyone got was a soviet NH3/F upper stage project, and that was cancelled after a few ground tests.

It is common sense. ClF3 is volatile(that is an understatement) and horrible to work with.

[rz6]

The S-IVB upperstage had some pressure fed auxilliary tanks (filled at launch, then refilled from the main tanks while the engine was running) for it's ullage engines, to be able to restart it for the transfer burn.

You don't mean the hypergolic APS pods, do you?

[CosmosGamer99]

I see a lot of people ask: "why not use this propellant", (please don't read this in a passive-aggressive sarcastic voice) and they forget that the Soyuz / R7 was THE FIRST space faring rocket.  While they have upgraded it, if they were to have done something as drastic as changing propellant or something else, they probably would have renamed it.  I notice the fact of the Saturn rockets and that is because they were only for one program (technically two because of Skylab, but it probably wasn't even a though before the last few Apollo missions.), so it would make sense to keep the name.  However, the reason the Falcon 9 was able to be so revolutionary was because it was designed from the ground up.  Modern day Delta and Atlas rockets a pretty different from their first variants, but what keeps some of them limited is that they are still based on that 50-80 year old technology.  Also, Russia does not have the same funding as NASA or ULA.  They haven't made any new rockets since the fall of the USSR.  It has all been Soyuzs (Soyuzi? Whatever the plural of Soyuz is.) and Protons since then.  Come to think of it, that is all they have ever used.  In the end, I think the main reason for the continued use of hot staging is funding, or lack there of.

[DDE]

Hello and welcome to the forum, @CosmosGamer99. You may wish to note that this thread is four years old, and some of the people here who are getting notifications from you may be a bit annoyed.

Not sure where you found the discussion on propellant, someone simply erroneously cited the Nedelin disaster.

[Vanamonde]

Nobody got a notification from this post unless he/she subscribed to the thread, so no harm done.