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Comment by ChuckMcM | Hacker News Reader

I am sure this is a huge relief to the Blue Origin folks to have these issues if not fixed, at least understood so that they can be fixed and the engine put into production.

Slightly more powerful than the SpaceX Raptor (550 lbf for the BE-4 vs 500 lbf Raptor) both engines are designed for re-use. As the BE-4 gets closer to production, and the Raptor gets some flight tests under its belt, a clearer picture on the thrust to weight and dynamic range of throttling will become better understood.

But the really awesome thing is three orbital class re-usable engines available from US vendors for the first time ever. This bodes well for the US space industry. Not so good for Aerojet/Rocketdyne which, in my opinion, has basically rested on its laurels as the "only game in town" for US built engines for far too long.

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Which engine (other than BE-4 and Raptor) is the other 'orbital class re-usable engine' that you speak of? The newly constructed RS-25 that's going to be produced in the SLS program is not reusable (lookup RS-25E).

- Merlin

- Raptor

- BE-4

For size comparison:

https://i.redd.it/wn6hk5s8n5e21.jpg

Merlin?

Ah, yes. I kind of looked over that engine. Oops...

I overlooked it mostly because the Merlin engine uses RP-1, and therefore has limited reuse life due to soot buildup in the engine (unless they've solved that problem). I also suspect that the Merlin engine only has limited time left as (when) SpaceX transitions to Starship.

Well, they were reusable when they flew in the shuttles, before SLS decided to discard them in the Atlantic.

Correct, but the RS-25 that are newly ordered from Aerojet Rocketdyne will not be reusable (not built to be reused).

Anyone that wants to order a reusable RS-25 can have Aerojet Rocketdyne configure and manufacture it that way. See also the AR-22 variant used on the ill-fated DARPA XSP program.

The real issue with that engine isn't its reusability, it's that the industry has learned a lot about rocket engine design, operation, and manufacturing since the RS-25 was developed. That's reflected in the engines available from the likes of Blue Origin and SpaceX. No knock on the RS-25 - it stands as a watershed achievement for humanity in the engineering of thermodynamic systems.

Though calling the SpaceX engines "available" needs the caveat that SpaceX will not make them available outside of SpaceX.

Weren't some of them refurbs? As in, shuttle hardware that was designed to be reusable and was reused is now planned to be unceremoniously dumped in the ocean?

In any case, even if the discardables are all new, it's a shameful step back. I am so glad they have competition now.

Rutherford

Good point! I suspect RocketLab will recover and reuse Electron before Blue Origin recovers and reuses New Glenn. RocketLab plans to test recovery (Ballute and then guided parachute until splashdown, not yet helicopter although they have had successful helicopter recovery tests of mockups) on the 17th Electron launch (3 launches from now), which is planned for this year.

The Aerojet Rocketdyne AR1?

Accordingly to Musk they are aiming for 300 bar chamber pressure and 3MN for the non-throttling version of the raptor, and that will make it more powerful than the 2.4 MN of the BE-4. Currently the throttling version operates at 2.1MN, so it’s a bit less powerful than BE-4.

FYI They hit 300 bar for a 90 second run last week before it started to have issues. Getting there.

https://twitter.com/elonmusk/status/1318708955628118025

For those of you that have not done hydrodynamics 1 Bar is roughly 14.5 PSI or 10.1 m of water

Just for clarification - those numbers are 550,000 lbf for the BE-4 and 500,000 lbf for the Raptor.

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