In article <qV%JI.27680$rr3....@fx34.iad>,
jfmezei...@vaxination.ca says...
>
> I'd always seen the Proton rocket as one of the big mastodooons of the
> rocket world. Needed to lift things like Zvezda etc.
>
> Today, I learned its capacity to LEO is just 23,000kg to LEO while the
> small Fakcon9's is 22,800. (some variants of Protol apparently to 23,700).
>
> And even more surprised to find that Proton is hypergolic from sea
> level. Would have expected it to be just a big Soyuz with Kerosene
> engines.
>
> Tried to read up on its history as an ICBM launcher. Have other
> countries ever used hypergolics from sea level?
US. The Titan II missile, Titan II launch vehicle, Titan III launch
vehicle, and Titan IV launch vehicle all used hypergolic propellants in
their liquid fueled stages. But the US doesn't use them anymore.
China is still flying launch vehicles which use hypergolic propellant.
And because their original launch site is inland, this results in
boosters with some remaining toxic chemicals being dropped on villages.
Giant Rocket Booster Nearly Hits School
Sep 10, 2020
https://www.youtube.com/watch?v=U43khdtocpo
If you see a BFRC (big, fracking, red cloud), run away!
> Was selection of hypergolics just to get something flying
> faster/cheaper/simpler (and it turns out it took over a decade to get
> approved) ?
Hypergolic propellants are super reliable to start. And you can easily
find hypergolic propellants that are storable at room temperature
(unlike the LOX oxidizer used in the Atlas missiles). Hypergolics were
therefore a "good" choice for missile propellants. But, the US quickly
developed solid rocket boosters which are also super reliable to start
and have none of the downsides of hypergolic liquid propellants (e.g.
toxic and/or corrosive). The Russians took much longer to develop solid
rocket boosters to use in missiles.
> I know that ignition is simpler, but do hypergolics that are more then
> mere thursters still need fancy turbo pumps and gasification prior to
> reaching combustion chamber?
Yes. Look at the Wikipedia pages for the launchers I mentioned above
and then click on the links for their first stage engines and you'll
find turbopumps.
> or is it really a question of low pressure spraying both liquids into
> combustion chamber and let the 2 mix and do their thing?
Yes for vacuum optimized, pressure fed, engines. No for sea level
engines which typically need turbopumps to obtain the necessary
combustion chamber pressure.
> Would the Protol that launched Nauka today have been built at same time
> as Nauka and just waited all these years, or would it be a recent build
> once they were reasonably sure Nauka was ready?
I seriously doubt that the Proton used to launch Nauka was built decades
ago.
> And is this officially the last Proton to launch and no more to bve
> built, replaced by Abgara, or is Angara still too immature to rule out
> further Protol launches?
Proton is sure to keep flying. Russia won't retire Proton until it
isn't "needed" anymore. And only Russia knows what that means.
Jeff
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