Possible Atlas V Russian Engines Solution.

[fredinno]

Could the Atlas V use RS-27As, used on the Delta II, instead of its current Russian RD-180?

My plan would be to switch 1x RD-180 to 4xRS-27As, whose production would be restarted, and densify the RP-1 fuel to allow RS-27s to be used (since RS-27s use a greater ratio of fuel).

However, since the lower ISP would result in lower payload mass, Delta II cores would also be added, as LRBs, with 4x maximum number of boosters, and (possibly) an extra RS-27A if the extra thrust is required. Propellant crossfeed could also be done of needed.

Longer, 30 meter versions of the existing Atlas SRBs could also be built, with only half of them on at once (or 3, if using 5 or 3 booster versions, or 1 if using 1 booster version) , and the other SRBs starting after inital SRB burnout, to lower the otherwise excessive TWR.

I think that this would be a faster, cheaper way of switching from RD-180s than Vulcan.

[Bill Phil]

Problems are various. The mixture ratios aren't the same. RS-27As and Delta II Cores aren't really "in production."

No gimbal, either. Or not enough gimbal.

Idk if den sifting the RP-1 could be done, since that would result in a greater pressure.

[fredinno]

Well SpaceX is densifying RP-1 just fine....

Also, why would there be a greater pressure on the tank? RP-1 is being cooled in propellant densification...

I know Delta II components are'nt in production, I accounted for that. How difficult would it be to restart production?

[Bill Phil]

Well SpaceX is densifying RP-1 just fine....

Also, why would there be a greater pressure on the tank? RP-1 is being cooled in propellant densification...

I know Delta II components are'nt in production, I accounted for that. How difficult would it be to restart production?

If there's more of something in a given space, pressure increases.

That depends on if the tooling is still around...

[Streetwind]

You cannot just swap engines in real life. They are not just tacked-on components like in KSP; rather, the entire first stage is built around the engine block, and there are no standard parts. Rocket engines are 100% custom hardware with zero intercompatibility, designed and built for one exactly specified job on one exactly specified launch vehicle.

ULA is designing the Vulcan because it's literally the same effort to build a new rocket as it would be to convert an existing one to new engines.

There is no real problem with the RD-180 tbh. It's a fantastic engine, performance-wise one of the best humanity has ever built, and it has never failed in all its years of operation. The problem is one that politics cooked themselves in-house, and I'd honestly rather see a political solution than a technical one. But I can also understand ULA hedging their bets and switching to a domestic manufacturer. They run a business, they need to launch, regardless of what the politicians do.

Edited September 3, 2015 by Streetwind

[1greywind]

RD-180 was developed by Energomash for joint USA-Russia enterprise that is holder of all schematics and rights for production. Initial goal was to start production of localized version of RD-180 on american soil. But as years passed, it was always cheaper to just order new batch of engines that start production of localized versions. Even now with all this "sanctions" nonsense, USA have all rights and schematics to start it's own production of RD-180 but it is still cheaper to make "exception" in sanctions list.

[Kryten]

RD-180 was developed by Energomash for joint USA-Russia enterprise that is holder of all schematics and rights for production. Initial goal was to start production of localized version of RD-180 on american soil. But as years passed, it was always cheaper to just order new batch of engines that start production of localized versions. Even now with all this "sanctions" nonsense, USA have all rights and schematics to start it's own production of RD-180 but it is still cheaper to make "exception" in sanctions list.

RD-180 production in the US isn't a solution, the legislation set to be introduced bans use of engines produced or designed in Russia.

[Kibble]

Rocket engines are 100% custom hardware with zero intercompatibility, designed and built for one exactly specified job on one exactly specified launch vehicle.

That's a bit of an exaggeration. Rocket engines have flown on multiple launch vehicles - a relative of RS27 was even used as the booster on former Atlas rockets!

[Kryten]

You cannot just swap engines in real life.

Orbital are literally doing that right now on Antares, so...

[Budgie]

I think we can all agree that it's not as simple as clicking th engine to the left of the screen and attaching another on the same node. There are studies to be done, piping to be reworked, and performance statistics to be calculated.

[Streetwind]

Orbital are literally doing that right now on Antares, so...

...With the Antares getting a completely new first stage in the process, which is why the finished vehicle will be called Antares-200

The Antares rocket is built to allow swapping entire stages. Orbital ATK has done so before: the solid upper stage of the Antares, for instance, has also been replaced by a higher performance model. (Unfortunately it was supposed to fly for the first time on the mission that fell back onto the pad, so we've yet to see it in action.) What they are doing right now is not that much different - they are simply swapping the first stage instead. The thing that takes time is the fact that the replacement stage just isn't fully developed and tested yet, because it was supposed to be introduced a year later originally.

The Vulcan incidentally isn't that different either... the introduction variant will combine a new first stage with the existing Centaur upper stages. ULA is splitting the development up, doing the first stage first (to get rid of the RD-180 dependency) and then, once that flies, turning their attention to the upper half of the new rocket.

Edited September 3, 2015 by Streetwind

[Kryten]

...With the Antares getting a completely new first stage in the process, which is why the finished vehicle will be called Antares-200

No, the completely new stages are the 300 series, lengthened to take advantage of the extra thrust. They're literally fitting new engines to the stages that have already been built.

[fredinno]

But is it cheaper than the Vulcan solution?

[Kryten]

If it wasn't they'd have thrown out these cores and filled the gap with more Atlas V orders.

[Bill Phil]

That's a bit of an exaggeration. Rocket engines have flown on multiple launch vehicles - a relative of RS27 was even used as the booster on former Atlas rockets!

And the RS-27 is a decendent of the H-1, which was at least similar to the BM-3.