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

[Skye]

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?)

[rfdesigner]

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 doubt anything will beat the chopsticks for speed & efficiency unless it's a much less capable craft where it just takes less time to refuel.  Landing at the launch tower will always win (once you get past the issue of inspections) 
I would say the chopsticks is the easiest once you've got your landing/catching code perfected, and SpaceX look like they're pretty close on that.

Safety?  (less risk) that comes down almost entirely to experience and that means repetition.  Aircraft are only safe landing on a runway because they've done it enough everyone has learnt from all the mistakes.  F9 brings many lessons to VTVL landings, hence SpaceX have reflown a Starship booster much sooner than they reflew a F9 booster, because they weren't starting from zero.  Additionally SpaceX's policy only flying people after you've proved out the system with lots of cargo is sound, so you need to find someone else doing that (it certainly isn't NASA, where they try and fly people on 1st/2nd/3rd flights) arguably the Russian Soyuz rockets have benefitted from a lot of cargo launches so the human launches they've done benefit, i.e. are probably safe, but it's no guarantee, they merely an opportunity to find safety.  Finally reusability lets you inspect everything after each flight, thus you have the chance to find out if your design is marginal, where you can't do that when you discard most or all of the rocket.

So you'd be looking for a rocket that's reusable and has flow many many times, there's only one candidate.  Falcon 9

A more flippant answer might be: Helicopters..  but I don't think that's what you mean.

[gin455res]

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?)

Roton maybe? It had a helicopter rotor for landing, though i think it may have left the test pilot scared iirc. I wonder if an auto-rotating synchropter would work better. Maybe no Good for a supersonic terminal velocity. So only for small fat stages.

Doubt anything is faster than chopsticks.

[Paul451]

Roton maybe? It had a helicopter rotor for landing,

I doubt a Roton-like system could return onto its launch stand. Just a landing pad nearby.

Hard to beat actually landing within the very mechanism used to integrate the stages together on the launch pad.

That said, once you've cracked a reliable return-to-launch-site, I don't think the difference between Chopsticks and being retrieved from a landing pad will make that much difference for most launch providers.

[edzieba]

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?)

Eliminate the tower (or at least, eliminate the requirements for the tower and any crane/arms to handle dynamic landing loads) and land directly on the launch mount.

[Skye]

Catch cables - anyone?

[Jim]

Catch cables - anyone?

Not "less risky, and faster & easier "

[spacenut]

One of the original Shuttle designs had a very large fly back booster to take the shuttle as high as possible, then separate the shuttle and fly back and land to be restacked and reflown.  Shuttle was the same or similar to what they built.  This was VTHL for both using wings.  Don't know if it would have been any cheaper, but doubt it. 

I think what SpaceX is doing with the Superheavy is probably the most efficient, especially if they could have landing down stream to use less fuel for flyback to allow for heavier payloads. 

[AmigaClone]

For landing locations with gravity equal or less than Mars, I can see that what basically would amount to an empty concrete pad with a nearby propellant farm might be faster.

[redneck]

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

[Apollo22]

Catch cables - anyone?

Not "less risky, and faster & easier "

I don't disagree with that statement. Just saying it will be interesting to see whether the chinese can master that trick - or not.

[rfdesigner]

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

HTHL works best  when you have wings

VTVL works best when you don't

Wings on spacecraft are dead weight for launch.

Spacecraft don't need wings to land.

[Jim]

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

not with chemical propulsion

[Twark_Main]

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?)

Eliminate the tower (or at least, eliminate the requirements for the tower and any crane/arms to handle dynamic landing loads) and land directly on the launch mount.

I think this is the only answer that actually makes good engineering sense.

The joke response (that makes no engineering sense....  at least I think) is that the Starship upper stage should also land on the hot-staging ring.   


Why do I say it makes no sense? After all, it's fewer engines than staging! However the SL Raptors will be overexpanded so the exhaust won't spread out like it will at altitude. Also you need a tower anyway for the crew access arm, however in theory crew access could be done in other ways.  Also it's simply unnecessary risk and unnecessary cycles to fragile flight hardware. If SH hit the final (even beefier) S0 it would be like a fly hitting a window (vs SS hitting SH which would destroy SH), and S0 can be beefed up for repeated cycles without big concern over mass penalty.

But hey I've been surprised before, so...

[redneck]

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

HTHL works best  when you have wings

VTVL works best when you don't

Wings on spacecraft are dead weight for launch.

Spacecraft don't need wings to land.

From a purely technical standpoint, you are correct. The driver for (eventual) horizontal will be in the regulatory realm. Noise abatement and flexibility of site locations using existing infrastructure. Low noise and high reliability will enable a first stage from thousands of airports world wide, which is enormously cheaper than building dedicated Starbases in multiple locations. The second or third stage return to Earth will either need to be low noise or considerable distance from complaining residents. That suggests an air breathing engine and HL to get close to target destinations.

This is not to suggest that any of the current HTHL options make sense. It will be after a singularity such as happened in December 2015.

[TrevorMonty]

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.

[rfdesigner]

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

HTHL works best  when you have wings

VTVL works best when you don't

Wings on spacecraft are dead weight for launch.

Spacecraft don't need wings to land.

From a purely technical standpoint, you are correct. The driver for (eventual) horizontal will be in the regulatory realm. Noise abatement and flexibility of site locations using existing infrastructure. Low noise and high reliability will enable a first stage from thousands of airports world wide, which is enormously cheaper than building dedicated Starbases in multiple locations. The second or third stage return to Earth will either need to be low noise or considerable distance from complaining residents. That suggests an air breathing engine and HL to get close to target destinations.

This is not to suggest that any of the current HTHL options make sense. It will be after a singularity such as happened in December 2015.

You can write all the regulations you like, you can't launch significant mass to orbit starting horizontally.

All "fly an aircraft to altitude then drop the rocket and launch" solutions have failed commercially because you save almost nothing from the rocket performance requirement by doing so but add lots of complexity, cost and risk trying to fly an aircraft to do this.

You're fighting physics, and physics has a habit of winning.

Getting to orbital altitude is relatively trivial: potential energy = mass * g * height = 2.45Gjoules per ton to 250km altitude.

Getting to orbital velocity is 11.5 times harder: kinetic energy = 1/2 m * v ^2 = 28.1Gjoules per ton (orbital velocity is roughly the same for all LEO altitudes)

This means if you could fly your rocket on a balloon to orbital altitude then launch it, you still need 92% of the energy you needed from ground level to achieve orbit.

Now look at the rocket equation.

DeltaV = ISP * g * ln(Me/Mo)  Me = empty mass, Mo = mass at t=0 or "full mass".  The empty mass kills your performance so must be minimised.

Now consider the stresses on a rocket when launched vertically, all the stresses are inline, on the pad, during launch all the way to separation, this makes the design relatively possible.

What if we want to tilt it sideways to launch horizontally?..   suddenly you'll overstress many many parts, you'll need to add mass to stop it collapsing, that added mass means reduced performance.  You can get an 8% performance boost launching from extremely high altitude, but you have a lower performance rocket, you save very little, but incur higher operating costs and make the rocket design much harder.

You also have the issue of maximum aircraft payload mass.  The Ukrainians had the biggest heavy lift aircraft before the Russians destroyed it, at 250ton payload.  Were that to be used to carry a rocket you're limiting rockets to a maximum of 250tons.

Rockets typically max out at delivering around 3% of their initial mass as payload to orbit, with the rocket mass being hard limited to 250 tons that means you can't deliver more than 8 tons to orbit,

The only way round all of this is a engine technology that can deliver substantially improved performance from much less fuel without irradiating the earth.  Nothing we have, and nothing even discussed by those in the know have suggested anything that would fit that requirement.  Ion drives are too weak, NTRs are too toxic etc etc.

The nearest project is the old HOTOL/SABRE, but the engine requirements are horrible, even if they were to function I can't see them being any quieter, so there's no way you'd want one of those things taking off from from the average airport, and the project has folded more than once, it's just too impossible.

[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.

[Jim]

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.

In addition to useless wing mass, now there is useless jet engines.

[Jim]

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.

[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.