Alternative VTVL landing systems from rapid reuse (within the hour - or two)

[rfdesigner]

1st stage whether it is VT of HT with wings will need liquid rocket engines as they can operate at hypersonic speeds and altitudes required. Stage too slow or low and 2nd stage will have to provide lot more DV, resulting in more expensive and larger 2nd stage.

Large rocket powered LVs can't operate from airports because of dangerous noise levels they produce and large explosion in case of RUD.

The options I've seen discussed involve airbreathing from runway to +-30,000 feet when the pitch up maneuver starts along with rocket ignition. Staging at +-Mach 6 and 50+ km altitude.

Launching at Mach 6 saves you 5% of your orbital energy requirements.

That's a tiny benefit for a monstrous amount of technology

[redneck]

Low noise and high reliability will enable a first stage from thousands of airports world wide,

This is the fallacy.  Don't need thousands of runways (or any at all).  Much like deep water ports, only need a few.

Depends on eventual traffic level along with the origins and destinations of that traffic. Not everybody is served by limited access.

[redneck]

1st stage whether it is VT of HT with wings will need liquid rocket engines as they can operate at hypersonic speeds and altitudes required. Stage too slow or low and 2nd stage will have to provide lot more DV, resulting in more expensive and larger 2nd stage.

Large rocket powered LVs can't operate from airports because of dangerous noise levels they produce and large explosion in case of RUD.

The options I've seen discussed involve airbreathing from runway to +-30,000 feet when the pitch up maneuver starts along with rocket ignition. Staging at +-Mach 6 and 50+ km altitude.

Launching at Mach 6 saves you 5% of your orbital energy requirements.

That's a tiny benefit for a monstrous amount of technology

So your argument is that Starship doesn't gain much from Superheavy?

[SpaceLizard]

1st stage whether it is VT of HT with wings will need liquid rocket engines as they can operate at hypersonic speeds and altitudes required. Stage too slow or low and 2nd stage will have to provide lot more DV, resulting in more expensive and larger 2nd stage.

Large rocket powered LVs can't operate from airports because of dangerous noise levels they produce and large explosion in case of RUD.

The options I've seen discussed involve airbreathing from runway to +-30,000 feet when the pitch up maneuver starts along with rocket ignition. Staging at +-Mach 6 and 50+ km altitude.

Launching at Mach 6 saves you 5% of your orbital energy requirements.

That's a tiny benefit for a monstrous amount of technology

So your argument is that Starship doesn't gain much from Superheavy?

If I understand correctly, in order to launch a useful vehicle, e.g. something half Starship's size or larger; from a HTHL first stage would require that stage be even larger and louder than Superheavy is already. Rendering the use of airport runways completely impossible for any worthwhile launch mass without the development of technology that defies our current understanding of physics and energy.

[Jim]

Depends on eventual traffic level along with the origins and destinations of that traffic. Not everybody is served by limited access.

Space flight is not going be like airline traffic.

[TrevorMonty]

Dawn's Auroa MK2 is only HTHL spaceplane in operation, not quite made it to space yet but working towards it. They've seemed to have mothballed idea of larger MK3 that would be 10-20mt wet. This would use expendable 2nd stage to deliver 250kg of payload to LEO.
I suspect economics didn't workout, ie lot $$ R&D to go head to head with Electron. How they'd get on with flight approvals for this larger RLV/spaceplane is anybody's guess. They've layed groundwork in NZ with MK2 but in any other country would be starting from scratch.

[Paul451]

VL does seem to be the recovery of choice for now. I predict that in a few decades HTHL will predominate.

Low noise and high reliability will enable a first stage from thousands of airports world wide

Even if you could take off under jet power and get far enough away before lighting the rockets, you can't do propellant loading at "thousands of airports", due to the risk of having so much LOx next to so much fuel.

No commercial airport is going to let you force an evacuation of the airport and surrounding area every time you launch. Not to mention flying that bomb over cities that airports are built near. Not to mention the effect on air-traffic around the airport due to the wide corridor that needs to be cleared before taking off.

[redneck]

1st stage whether it is VT of HT with wings will need liquid rocket engines as they can operate at hypersonic speeds and altitudes required. Stage too slow or low and 2nd stage will have to provide lot more DV, resulting in more expensive and larger 2nd stage.

Large rocket powered LVs can't operate from airports because of dangerous noise levels they produce and large explosion in case of RUD.

The options I've seen discussed involve airbreathing from runway to +-30,000 feet when the pitch up maneuver starts along with rocket ignition. Staging at +-Mach 6 and 50+ km altitude.

Launching at Mach 6 saves you 5% of your orbital energy requirements.

That's a tiny benefit for a monstrous amount of technology

So your argument is that Starship doesn't gain much from Superheavy?

If I understand correctly, in order to launch a useful vehicle, e.g. something half Starship's size or larger; from a HTHL first stage would require that stage be even larger and louder than Superheavy is already. Rendering the use of airport runways completely impossible for any worthwhile launch mass without the development of technology that defies our current understanding of physics and energy.

One of the current fallacies is that launchers must be huge. Actually they must become economical. The 8 tons suggested upthread is quite adequate for the majority of payloads. Well within weight limits of many airports. Heavy lift is needed for relatively few. The question, as always, is what does it cost? Airbreathing engines are notably quieter than rocket engines.   

Also, I was responding to a statement that Mach 6 staging doesn't get you much. That being in the neighborhood of Starship staging makes that statement quite interesting.

[redneck]

Depends on eventual traffic level along with the origins and destinations of that traffic. Not everybody is served by limited access.

Space flight is not going be like airline traffic.

True, but it's also not going to be like ocean traffic.

[Jim]

One of the current fallacies is that launchers must be huge. Actually they must become economical. The 8 tons suggested upthread is quite adequate for the majority of payloads.

Wrong.  That is at GEO. 

[redneck]

VL does seem to be the recovery of choice for now. I predict that in a few decades HTHL will predominate.

Low noise and high reliability will enable a first stage from thousands of airports world wide

Even if you could take off under jet power and get far enough away before lighting the rockets, you can't do propellant loading at "thousands of airports", due to the risk of having so much LOx next to so much fuel.

No commercial airport is going to let you force an evacuation of the airport and surrounding area every time you launch. Not to mention flying that bomb over cities that airports are built near. Not to mention the effect on air-traffic around the airport due to the wide corridor that needs to be cleared before taking off.

It would be interesting to revisit those limitations in several decades. Not in the next couple obviously. Mature technology and procedures will change some of the limitations. The question being how much? Then there's also the wild card concepts that can make a difference. I never heard of hoverslam before it was a fact.

[SpaceLizard]

One of the current fallacies is that launchers must be huge. Actually they must become economical. The 8 tons suggested upthread is quite adequate for the majority of payloads.

Crew dragon weighs a little over 10 *12* tons, if you can only lift 8 you're not getting much of anything to orbit; 'cept micro-sats...
*Edited*

[Apollo22]

VL does seem to be the recovery of choice for now. I predict that in a few decades HTHL will predominate.

Low noise and high reliability will enable a first stage from thousands of airports world wide

Even if you could take off under jet power and get far enough away before lighting the rockets, you can't do propellant loading at "thousands of airports", due to the risk of having so much LOx next to so much fuel.

No commercial airport is going to let you force an evacuation of the airport and surrounding area every time you launch. Not to mention flying that bomb over cities that airports are built near. Not to mention the effect on air-traffic around the airport due to the wide corridor that needs to be cleared before taking off.

Good arguments here.
I was wondering whether hydrogen airliners could help the case of hydrolox rocketplanes ?
This is a study of LH2 integration into airports.
https://www.ati.org.uk/wp-content/uploads/2021/08/aci-ati-hydrogen-report-1.pdf

If hydrogen airliners happens, then a kerolox rocketplane face mostly similar issues : one deep cryogen at airports. LOX being slightly less cumbersome than LH2.

Nota bene: I truly hate the very concept of an hydrogen airliner - make no mistake.

[Twark_Main]

Thinking that HTHL or VTHL will ultimately "win" because of existing airports is like expecting seaplanes would ultimately "win" because of existing seaports.



Seaplanes were a transition technology before airports could be built, but once airports were built the additional mass and cost of a seaplane was uncompetitive with true modern airplanes.

Rockets have already leapfrogged over this possible transitional state and have gone straight to their ultimate VTVL configuration.  This is partly because building orbit-class rockets is harder than building commercial airplanes, so with rockets you can't afford the cost to begin with.



More importantly, this thread is for VTVL designs.  HTHL or VTHL is off-topic in this thread.

Are there other potential landing VTVL systems out there more efficient, less risky, and faster & easier than the chopsticks? Something that works for all potential stages, too? (ie: booster, upper stage, kickstage?)

I expect "landing directly on the pad with no tower" is the only viable answer.



The more I think of it, the more I believe Starship landing directly on the hot staging ring is the correct answer. They can gimbal the center engines outward and run at low throttle to minimize wear on the interstage. Since the interstage and truss need a heat shield anyway for hot staging, this isn't a big cost.

Along with routing the fill/drain plumbing up Super Heavy (a small penalty), this completely eliminates the need for a tower.

Passengers can be loaded in large lifting transporters or a small lightweight (retractable?) tower.

(Non-methalox) cargo is loaded by landing Starship on a pad, loading cargo with a cheap low-rise crane, and hopping back onto Super Heavy. 

"Replace hardware with software."

[edzieba]

On the seaplane topic:

Eliminate the pad and tower completely. Take off a-la Sea Dragon with the stack partially submerged. 'Land' by hitting zero velocity and zero altitude and cutting the engines, with the suitable mass distribution for the engines at the aft end to keep the rocket body upright as it bobs fishing-float-like, or with a rocket body that can tolerate tipover to horizontal without failure (e.g. via terminally deployed airbags, or just sufficient structural reinforcement).

We know partially submerged launch works at small scale from testing by Robert Truax. We know that rocket bodies that can survive ocean landing and tipover at least without a RUD are possible from Falcon splashdowns, so a rocket body that can survive tipover without damage is not unreasonable.

The kicker is whether a vessel to tow the rocket body back into place for GSE hookups (and the annoyances of GSE without any solid G to put it on) is more of a hassle than giant electrohydraulic chopsticks.

[Paul451]

[Sea launch/landing]
The kicker is whether a vessel to tow the rocket body back into place for GSE hookups (and the annoyances of GSE without any solid G to put it on) is more of a hassle than giant electrohydraulic chopsticks.

Also what does dunking the hot rocket engines in sea water do to their service life. And what happens to the structure when a 5 story building falls over, water isn't "soft" at that velocity. And how you inspect/service/swap-out the engines when they're floating under water at the bottom of the rocket (which favours a tip-over model, but even then... trying to service a rocket engine on the open sea? Ick. And if you tow it back to a drydock, how much time and cost does that add, reducing flight-rates.)

Aside: Being tail-heavy doesn't solve the tip-over issue. Take any tall cylinder that floats at rest vertically, it will still initially tip over when dropped into water. The tail decelerates before it has sunk to its natural floating depth, then descends slowly, leaving it effectively top-heavy. After tipping over, it will immediately start to flip back vertically, but you can't prevent that initial tip.

you can't do propellant loading at "thousands of airports", due to the risk of having so much LOx next to so much fuel.

I was wondering whether hydrogen airliners could help the case of hydrolox rocketplanes ?
This is a study of LH2 integration into airports.

It's not about whether you could have LH available, it's having hundreds of tonnes of LOx next to any fuel, in the rocket itself. A leak becomes a fire, igniting a giant bomb. Not just in its service area/hanger while its being fuelled, but during taxiing and roll-out, during take-off, during overflight of the area around the airport (include the need to abort on take-off, loop around the airport, and return to landing.)

There is not a single commercial airport in the world that will allow a rocket plane to use it. Only specialty "spaceport" type airports, like Spaceport America and similar. And there aren't going to be "thousands" of those.

Don't get me wrong, I'm a big fan of HTHL. (At least for the first stage.) There's many advantages: being able to fly to your launch window/inclination/etc; being able to ferry around weather; the first-stage/carrier being (by definition) big enough to transport its own payloads from the manufacturer to the integration area; likewise being able to ferry itself and its upper-stage from the manufacturer to testing and integration areas; etc. And if you can solve the runway GTOW problem, I suspect the wasted mass of wings/wheels on the first-stage is worth those benefits.

The "runway GTOW problem" is that taking-off from even a long runway severely limits how much propellant you can carry with any given wingspan, which severely limits the payload to orbit, reducing you to flying smallsats, which can't pay for a rocket development program, let alone something as ground-breaking as HTHL.

Funnily enough, a ekranoplan type launch from water might solve both the GTOW problem and the sea-landing issues.

HTHL sea-launch for the win.