Author Topic: Europe joins the re-usability bandwagon?  (Read 28013 times)

Offline TrevorMonty

Re: Europe joins the re-usability bandwagon?
« Reply #120 on: 08/08/2022 10:55 am »

I'm a bit shy on my math here but:

What would be the implications of a (reusable) first stage with a slightly ad-hoc tripropellant combination?  Say, an engine cluster containing both Prometheus and Vulcain engines?  The Prometheus engines can do much of the thrust at the start of flight, light the A5 / A6 do with solids, and then swap to Vulcain only later in the primary flight, improving the specific impulse of the stage over all?  Then use the Prometheus engines for landing, and the boost back and / or re-entry burns, if those exist?  Would this help to reduce the extreme wet mass requirements of re-usability from an all Prometheus stage?  Would using hydrogen in a first stage make it unacceptably high volume?

The extra tanks required for LH would add so extra dry mass that any gains from LH higher ISP would be loss. LH is better as US propellant.
« Last Edit: 08/08/2022 09:51 pm by zubenelgenubi »

Offline Rik ISS-fan

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Re: Europe joins the re-usability bandwagon?
« Reply #121 on: 08/08/2022 06:36 pm »
I also think the tripropallent combination is to complicated. I expect a 2.5 stage design beside a two stage design. Ariane 5 and 6 are 2.5 stage designs. The solid boosters could be replaced by (reusable) liquid boosters. I expect only two liquid boosters will be used. This will be a heavy version of the launcher. A lighter version will lift an upperstage and possibly an in-orbit/kick stage.
Let them mess around with Callisto and/or other small demonstrators to develop efficient stage recovery methodes.
SpaceX used landing legs on Falcon 9, but plans to use a catch tower for super heavy and starship. Rocketlab plans parachute recovery with mid-air capture. There are also ideas for wire catch mechanisms in Europe. I think tests on small rockets will have to show what is the best option. They need to plan for the fact they will destroy a couple of vehicles, that's required to figure out the best stage recovery method. If they launch the demonstrator to more than 100km altitude with scientific payloads each launch also has another use. I expect this will cost roughly half a billion euro and take several years.
I think the (first stage of) Sirius1 from Sirius Space Services, could be a succesor to Callisto. Or the first stage of one of the ther European micro launchers. Themis is to large for a technology demonstrator, and it requires the engines to be operational, that delays the stage recovery tests a lot.
The Sirius 1 uses 38kN pressure feed LOx LCH4 engines, simple, thus cheap and reliable.
« Last Edit: 08/08/2022 06:42 pm by Rik ISS-fan »

Offline libra

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Re: Europe joins the re-usability bandwagon?
« Reply #122 on: 08/09/2022 02:55 pm »
TAN was an interesting innovation for tripropellant rocketry, unfortunately it seems to be locked at Aerojet...

Online Solarsail

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Re: Europe joins the re-usability bandwagon?
« Reply #123 on: 08/09/2022 08:40 pm »

I'm a bit shy on my math here but:

What would be the implications of a (reusable) first stage with a slightly ad-hoc tripropellant combination?  Say, an engine cluster containing both Prometheus and Vulcain engines?  The Prometheus engines can do much of the thrust at the start of flight, light the A5 / A6 do with solids, and then swap to Vulcain only later in the primary flight, improving the specific impulse of the stage over all?  Then use the Prometheus engines for landing, and the boost back and / or re-entry burns, if those exist?  Would this help to reduce the extreme wet mass requirements of re-usability from an all Prometheus stage?  Would using hydrogen in a first stage make it unacceptably high volume?

The extra tanks required for LH would add so extra dry mass that any gains from LH higher ISP would be loss. LH is better as US propellant.


I wish I knew how to run the numbers on that.  What struck me was the extreme Δv requirements of accelerating to stage velocity and then braking for reentry within this thread: https://forum.nasaspaceflight.com/index.php?topic=41330.180  (Maybe I should have posted there instead?  More context..)

The optimum separation velocity leaves a amount of work for the upper stage to do, and needs a huge first stage for it.  Thus my thinking of a stage splitting the differences between Prometheus and Vulcain engines.  You would need a less extreme stage volume than a Delta IV by doing much of the impulse in denser methalox, you would raise the average effective specific impulse for the flight (for a high Δv flight) and have restart / landing capabilities in the less efficient engines.  At least, landing burns look to require fairly little Δv, so the reduced isp is less painful there.  Thus the heterogeneus engine cluster, sitting between low-isp, higher density and higher stage T/W (including tank mass) on some engines and higher isp, lower density, lower stage T/W on the others.  And accomplishing this variable ISP behaviour without needing exotic engine designs.  Admittedly, by adding an exotic cluster of engines.

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