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> Could anybody here comment on the differences between spacex's engine, and the engines on the space shuttle? It's sort of apples vs oranges to compare the Sh

> Could anybody here comment on the differences between spacex's engine, and the engines on the space shuttle? It's sort of apples vs oranges to compare the Shuttle main engines vs the Falcon 9 engines, because the Shuttle main engines were on the the crewed upper stage of the Shuttle stack and the Falcon 9 booster is the boost stage of the Falcon 9 stack. The direct comparison is comparing the Falcon 9 booster (first stage) with the solid rocket boosters of the Shuttle stack, and comparing the Shuttle with the Dragon. Dragon v1 has a heat shield (like Shuttle) and then parachutes (unlike Shuttle). Dragon 2 will have reusable engines to land propulsively, which means it will land on land like the Shuttle. The Falcon 9 booster is much, much more sophisticated than the Shuttle boosters. The Shuttle boosters were solid fueled; once lit they could not be turned off or throttled. They just burned at maximum thrust until they ran out of fuel, which is why they needed parachutes to land in the ocean. Unfortunately NASA learned that salt water is terrible for engines, even if they land gently, and the cost of refurbishing the boosters after each launch (and the amount of time it took) was much higher than anticipated. Falcon 9's Block 5 booster should (hopefully) reach a point where it can land, get refueled, and immediately take off again, like a 747. > I was under the impression that SpaceX was trying to make the first re-usable rocket stage, but I've recently found out that that isn't true. The space shuttle already holds that title. For the reasons I have above, you were right the first time. SpaceX is trying to make the first reusable booster that achieves orbit. Both Shuttle and Blue Origin's New Shepard are reusable, but neither of them can reach orbit by themselves. > I'm also kindof curious why they decided to go with a vertical-landing-design, instead of putting some wings on it and having it glide home like the shuttle did. Scaling laws. Vertical take-off, vertical landing (VTVL) rockets scale to any size. Wings don't. The Falcon 9, the Falcon Heavy, and future mega-rockets will all be able to use the same basic technology. Wings don't scale well at all.

bluGill 10y ago
> Vertical take-off, vertical landing (VTVL) rockets scale to any size. Wings don't. The Falcon 9, the Falcon Heavy, and future mega-rockets will all be able to use the same basic technology. Wings don't scale well at all. You are correct about the disadvantages of wings, but wrong about why SpaceX isn't using them. SpaceX has always had the goal of landing on Mars and returning home. All their rockets have been developed with this in mind. They tested their first rocket, and got it to work. They sold it to Nasa and the like (and even developed it with some of their requirements in mind), but the goal was always to learn how to make bigger rockets that can get to Mars, that Nasa is willing to pay for the smaller ones is a side benefit. Mars does not have enough atmosphere for wings to work, therefore SpaceX is not interested in Wings. Even if reuse of the rocket was clearly more expensive that building a new one each time (it isn't) SpaceX would be working on reusable rockets now because when they get to mars they need to land the rocket and latter reuse it to return back to earth.

bluGill 10y ago

> Vertical take-off, vertical landing (VTVL) rockets scale to any size. Wings don't. The Falcon 9, the Falcon Heavy, and future mega-rockets will all be able to use the same basic technology. Wings don't scale well at all. You are correct about the disadvantages of wings, but wrong about why SpaceX isn't using them. SpaceX has always had the goal of landing on Mars and returning home. All their rockets have been developed with this in mind. They tested their first rocket, and got it to work. They sold it to Nasa and the like (and even developed it with some of their requirements in mind), but the goal was always to learn how to make bigger rockets that can get to Mars, that Nasa is willing to pay for the smaller ones is a side benefit. Mars does not have enough atmosphere for wings to work, therefore SpaceX is not interested in Wings. Even if reuse of the rocket was clearly more expensive that building a new one each time (it isn't) SpaceX would be working on reusable rockets now because when they get to mars they need to land the rocket and latter reuse it to return back to earth.