Reusable, winged versions of the Saturn V first stage

publiusr

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Wing-mass allows orbiter to be a more flat, stable platform than capsules. Wings are even better for fly-back boosters in that you only light the engines once-and the engines have a much more benign thermal environment upon return than VTOVL designs like Musk's first stages endure. The wing's inert mass is a feature-not a bug...especially if it pays for itself as a kerosene wet wIng. The engines will last longer...
 

martinbayer

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As an aerospace engineer, before a systematic parameter driven case specific evaluation, I'm completely agnostic to a trade between turbojets/turbofans/rockets for booster reentry ballistic/glide return based on cost/mass/reliability/environmental pre-screening.
 

Byeman

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Wings do not "only serve the purpose of landing" - they are also instrumental for reentry, glideback, and TAEM, see Shuttle CONOPS. Musk understandably chose VTVL simply because there are no substantial atmosphere and landing strips on Mars (or the Moon, for that matter). Circumstances are a bit different here on Earth. Another important aspect is that wings (apart from moveable aerodynamic controls) are largely a passive structure, whereas rocket engines are highly energetic machines, with cumulative burn time being a limiting factor. From a basic engineering perspective, it makes sense to add comparatively simple structures to decelerate a reusable vehicle rather than waste propulsion system life on something environmental friction can easily take care of for you.
Not true. From a basic engineering perspective when engines are inexpensive and easily replaceable, it makes more sense to use them than carry needless mass around.

So jets instead of rockets to land with, that makes some sense as we've known that jets are vastly cheaper and more reliable than rockets and use less propellant fraction. Bonus if you cut them down to just the 'fan' stages. Somehow though I don't think that's where you were going though :)
Also don't have the additional cost of managing large area of TPS. Instead of burning propellant to haul needless wings and TPS, use it for landing.

Large area TPS is actually easier to do than low area TPS though, especially if you design towards a more lower-mass/higher surface area design. "Needless" isn't a 'fact' btw it's really a matter of opinion and design philosophy.

Randy
Not really. Jet engines are almost as useless as wings. The rocket engines are just as cheap for the same equivalent thrust and not useless mass for the bulk of the ascent or descent. And jet engines add more complexity to the design.
 

publiusr

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But jets last longer. Wings with jets means the rockets ignite only once-and then well above a flame trench absent on drone ships. The rockets just need be in a package that a heavy forklift can remove at ground level. That may allow easier handling than, say, moving a lighthouse around as SpaceX does?
 

RanulfC

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Not really. Jet engines are almost as useless as wings. The rocket engines are just as cheap for the same equivalent thrust and not useless mass for the bulk of the ascent or descent. And jet engines add more complexity to the design.

Rockets are NOT 'as cheap' nor do they have the same lifetime. Also they don't have to be that complex or massive. As I've noted elsewhere replacing the grid-fins with tip-turbine fans would allow a more controlled and easier landing. If we were talking something like "torch-igniters" or such you'd probably have a point about the ease and complexity but SpaceX for example uses a chemical igniter which it both limiting and dangerous.

Randy
 

Byeman

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Rockets are NOT 'as cheap' nor do they have the same lifetime. Also they don't have to be that complex or massive. As I've noted elsewhere replacing the grid-fins with tip-turbine fans would allow a more controlled and easier landing. If we were talking something like "torch-igniters" or such you'd probably have a point about the ease and complexity but SpaceX for example uses a chemical igniter which it both limiting and dangerous.

Randy
How much do you think a merlin costs? It is much less than $ 6 million apiece. Less than a CFM 56 engine. Raptor will be also.
The shorter life time doesn't matter, as long as they last as long as the LV airframe (which is going to be shorter than an aircraft)

"tip-turbine fans would allow a more controlled and easier landing." Unsubstantiated. And would be more complex than grid fins and more maintenance. The landing is already very controlled and easy. It has been done more than 80 times.

Raptor uses torch lighters. But dealing with the TEA/TEB is not a big deal. It is highly automated and only one ground tank is filled for the Booster. It is easier to manage than hydrazine.
 

publiusr

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A winged craft might be faster to turn around. Lying on its side--a forklift can drive up to the back and slide a whole boat-tail out and slide a new one in. No need to move a lighthouse. Merlins are pretty cheap in some respects, but won't last as long as a fly-back turbojet.

Again--fly-back rocket engines are spared the hoverslam--they have a more benign thermal environment in only igniting over a flame trench and not an unyielding pad. Thus a longer service life.

If a Falcon is good for 10 flights--a fly-back should at least double that--easily.
 

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