urmomaisjabbathehutt t1_j8rckmu wrote on February 16, 2023 at 12:07 PM

Reply to comment by holyrooster_ in After a decade in development, Japan’s H3 rocket is ready for its debut by DoremusJessup

how do we know till start developing it?

are we condemned to live with refining 1950 designs forever?, is that the best we can do?

pufftaloon t1_j8u1cab wrote on February 16, 2023 at 11:04 PM

Have you ever tried playing Kerbal space program? If you get into it you'll very rapidly understand why SSTO designs are not worth it.

Every kilogram of mass you have to lift to orbit requires multiple kilograms of fuel. And that extra fuel itself requires fuel to lift it. Staging allows you to jettison mass part way, meaning you need to carry significantly less fuel over all.

First stage reuse is a solved problem, and there's multiple very cool ideas for second stage reuse in development right now. We're so close to cracking this.

urmomaisjabbathehutt t1_j8ujz8w wrote on February 17, 2023 at 1:17 AM

you talk about the problem with extra fuel needed yet mention that there are some trying to develop a reusable second stage which incidently will require fuel

so lets watch the youtube video about why single stage rockets suck right? oh shit conbustible

meanwhile i'm talking about different technologies

hypersonic and sabre engines take advantage of the air in the atmosphere so they don't need to carry so much oxidizer with them

on a very quick search designs similar to this

https://physicsworld.com/a/air-breathing-rocket-engines-the-future-of-space-flight/

or this

[https://www.researchgate.net/publication/27524937_StarRunner_A_Single-Stage-to-Orbit_Airbreathing_Hypersonic_Propulsion_System]

still looking further ahead there are other technologies being explored and imho that can be explored further

holyrooster_ t1_j99tm6h wrote on February 20, 2023 at 10:10 AM

> how do we know till start developing it?

Because even the most optimistic assumptions about it, are already beaten by Falcon 9.

So if you can't even make it work on paper, how are you gone make it in real live?

> are we condemned to live with refining 1950 designs forever?

I mean you are stretching the definition of 'refining'. Starship is a just as much an upgrade over 1950 rockets then Skylon.

In fact, Skylon is actually how many people in the 1950 imagine the future, while Starship is the reality checked version of what will actually work.

> is that the best we can do?

If you want to really go invest in the future design, how about an air breathing nuclear turbofan. But I think that might cause some opposition.

You also need to consider that money is limited. Every $ going into air breathing engine isn't going into something that has potentially much greater effect. The investment done into Sabre engine would have yield far better results if it has been invested in reusable FFSC. Or something like a closed cycle expander areospike. Or many other things that that have far greater potential then Sabre.

The reality is that Sabre and Skylon are a product of a British team, a team of people that basically spend 20 years designing a bunch of paper rocket, having little experience what so with actual rocket flight operation and they came out with a concept they was so over-the-top that they thought they could get some serious research money finally.