Space Shuttle V2 Thought Experiment

[fredinno]

2 hours ago, sevenperforce said:

The reason I was going to suggest the tail-first retro burn was because the main propulsive engines are going to do a massively better job of slowing the ship down than hypergolic RCS engines, and with a lower propellant weight cost. I am trying to hammer out a design for an air-augmented engine that would be able to use the same engines to thrust vertically as horizontally without vectoring.

How is a drop-in fuel tank different from an internal fuel tank? And if I recall correctly, the Shuttle was retrofit to accommodate Shuttle-Centaur, not the other way around.

When did I say the ladning burn would not be done by the main propulsive engines? I just said that instead of the pitch down, the engine would just do all landing burns.

The problem with adding tanks is that taking the fuel out quickly in an emergency (such as abort) is more difficult, since the tank itself is enclosed (and thus more dangerous). Also, auxillarary tanks need a lot of extra plumbing- and the switching of tanks means you need to turn your engine off and restart it-otherwise bubbles can form and destroy the engine.

[Emperor of the Titan Squid]

On 2/9/2016 at 4:41 PM, sevenperforce said:

If you really want a replacement for the Shuttle, something that can put payloads into space regularly and be completely reusable...well, here you go.

41 meters high, 20 meters wide, 10 meters deep. Payload bay is the same size as the Shuttle Orbiter's, but the lack of control surfaces allows surrounding space to be used for additional fuel.

The engine is a truncated aerospike:

The high-thrust aerospike engines provide optimal thrust and Isp respective to altitude.

Optional/detachable cabin:

The crew cabin module has about half as much space as the Shuttle Orbiter but three times the space of the Dragon V2. It fits into the main body and is equipped with multiple high-thrust hypergolic engines which also act as the OMS and RCS system. These allow the crew cabin to eject during launch abort.

For crew transfer only, the payload bay is fitted with an additional internal tank and a disposable strap-on tank, allowing SSTO with the loss of the external tank alone. For unmanned flights, the crew cabin module is replaced with an autonomous control module with an auxiliary fuel tank but the same hypergolic engines. For manned flights including payload, or for higher-dV unmanned missions, 2-4 strap-on FH-style boosters are attached with propellant crossfeed; these detach at fairly low speed to return autonomously.

Re-entry will be...exciting. The aerospike already has to be able to handle very high heat fluxes and will probably already be actively cooled, so the orbiter enters tail-first and upside down to burn off most of its speed, with active use of the RCS system for stabilization. As soon as enough speed has dropped off, the orbiter begins to rotate forward, exposing more and more of its underside. The lower speed at this point means that the heat shield on its underside can be constructed of a lightweight, non-ablative, lower-performing, highly reusable material rather than requiring the tiles that the Shuttle used. Active RCS stabilization continues as speed decreases, ultimately entering a low-L/D gliding flight:

The orbiter does not make a very good glider and cannot manage a level approach, which is all the better because it doesn't have heavy landing gear. Instead, the RCS system returns the craft to a high angle of attack, and the aerospike engines are ignited, killing terminal velocity in a near-suicide burn. Then, the RCS system reduces power, allowing the angle of attack to drop until the orbiter is horizontal, and both the RCS system and the aerospike engines in combination fire to lower the orbiter to the ground:

If the aerospike cannot be directed downward enough to execute such a landing, then additional RCS thrusters can be incorporated in the aft portion of the orbiter.

Ambitious? Perhaps...but it seems like the best possible combination of geometry to allow for the capabilities of the shuttle with next-generation technology.

The amount of hypergolic fuel, internal fuel, and the number of strap-on boosters can be adapted to each mission. By using in-orbit staging and/or refueling, the orbiter could easily manage a lunar transfer. Depending on the fuel capacity of the crew cabin, it could manage a landing on its own on hypergolics, or lunar-orbit refueling could allow the entire orbiter to make the descent to the lunar surface and return to refuel and make the transfer to LEO again. The ability to take off and land vertically in a horizontal attitude reduces the instabilities and risks of vertical landings and allows far simpler crew egress.

I love this design, but as cool as the crew cabin is, it'l have to go.I still like a multiple interchangeable booster design,and think that serv without the cargo bay is best.Why doesn't anyone consider that?

[sevenperforce]

Just now, fredinno said:

When did I say the ladning burn would not be done by the main propulsive engines? I just said that instead of the pitch down, the engine would just do all landing burns.

The problem with adding tanks is that taking the fuel out quickly in an emergency (such as abort) is more difficult, since the tank itself is enclosed (and thus more dangerous). Also, auxillarary tanks need a lot of extra plumbing- and the switching of tanks means you need to turn your engine off and restart it-otherwise bubbles can form and destroy the engine.

A vertical tail-first landing is inherently unstable and egress is made highly difficult, which is why I'm aiming for a horizontal-attitude tail-first landing.

I didn't realize about the tank-switching thing...someone might need to design a constant-flow system.

Anyway, let's see here...next-Gen Shuttle, Take II.

Yes, it looks unlike anything we've ever launched. And it will definitely do SSTO.

The engines (not shown) are linear aerospikes, mounted on the sidewalls of the center body and the inside of the cowlings. Main fuel tanks are held in the cowlings. The engines on the central body point down and back; the engines on the cowlings point up and back.

There's an additional ring of aerospike engines around the inner cowling at the rear which point backward.

Takeoff and landing are both in a horizontal attitude. The engines mounted on the central sidewalls fire at full throttle, pulling air down over the upper fuselage and mixing inside the cowling before being ejected downward through the bottom of the cowling. RCS thrusters at the front of the fuselage (also not shown) fire to compensate for the slight forward push, and the spaceship rises vertically.

Once the ascent begins, the ship starts to nose up and all engines are ignited simultaneously.

The engines on the bottom of the inner cowling suck air in from below and thrust it backward, while the engines on the upper sidewalls of the central body suck air in from above and thrust it backward. This produces a highly-compressed vortex flow through the two openings at the back. As the ship accelerates, ram effect begins to contribute, as shockwaves entering the cowling are focused, heated by the side-mounted engines, and ejected out the back in a ramrocket configuration.

Due to the open cowling, the airflow is dramatically higher than for any ducted rocket ever conceived, allowing the craft to reach hypersonic speeds with only a fraction of the normal fuel costs. The transition to hypersonic speeds marks the end of air-augmented advantages, so this is timed to coincide with around 100 km of altitude. At this point, the side-mounted engines are throttled down to reduce acceleration and the rear engines provide the remaining orbital insertion burn.

Re-entry is a dream due to the high number of surface areas with which to dissipate heat. The side-mounted thrusters fire on approach to kill terminal velocity and make a soft touchdown on extensible landing legs.

For higher cargo requirements, launch can be vertically-positioned with strap-on boosters.

[fredinno]

3 hours ago, sevenperforce said:

A vertical tail-first landing is inherently unstable and egress is made highly difficult, which is why I'm aiming for a horizontal-attitude tail-first landing.

 

3 hours ago, sevenperforce said:

Yes, it looks unlike anything we've ever launched. And it will definitely do SSTO.

The engines (not shown) are linear aerospikes, mounted on the sidewalls of the center body and the inside of the cowlings. Main fuel tanks are held in the cowlings. The engines on the central body point down and back; the engines on the cowlings point up and back.

There's an additional ring of aerospike engines around the inner cowling at the rear which point backward.

Takeoff and landing are both in a horizontal attitude. The engines mounted on the central sidewalls fire at full throttle, pulling air down over the upper fuselage and mixing inside the cowling before being ejected downward through the bottom of the cowling. RCS thrusters at the front of the fuselage (also not shown) fire to compensate for the slight forward push, and the spaceship rises vertically.

Once the ascent begins, the ship starts to nose up and all engines are ignited simultaneously.

God, this looks like a nightmare to build. Also, reentry looks almost impossible.

3 hours ago, sevenperforce said:

Takeoff and landing are both in a horizontal attitude. The engines mounted on the central sidewalls fire at full throttle, pulling air down over the upper fuselage and mixing inside the cowling before being ejected downward through the bottom of the cowling. RCS thrusters at the front of the fuselage (also not shown) fire to compensate for the slight forward push, and the spaceship rises vertically.

Once the ascent begins, the ship starts to nose up and all engines are ignited simultaneously.

I think you need bigger wings for this.

 

[sevenperforce]

12 hours ago, fredinno said:

God, this looks like a nightmare to build. Also, reentry looks almost impossible.

I think you need bigger wings for this.

With the high number of heat-resistant surfaces, re-entry should be easy. Yeah, it has a high aerodynamic load so that means heavier construction, but enhanced thrust should make up for it.

Bigger wings for what? It's not a lifting body.

[Beowolf]

On 2/10/2016 at 9:10 AM, sevenperforce said:

That's why I rather like the idea of a cargo shuttle with a removable crew module, so it can take crew up SSTO by putting an internal tank in its payload bay OR be configured for heavy lift by swapping out the crew module for additional tankage and slapping on some reusable boosters.

Ah, so no SRBs needed when you're using the crew module? I like that!

[sevenperforce]

14 minutes ago, Beowolf said:

Ah, so no SRBs needed when you're using the crew module? I like that!

Exactly -- fewer failure modes, shorter turnaround time. I think this form factor can manage SSTO...it's got maximum internal volume, minimal ascent cross-section, and maximum re-entry cross-section.

I don't like the idea of landing a crew module tail-first, which is why I had the notion for a tail-first suicide burn followed by a controlled nose-down to horizontal attitude on the forward SuperDraco-style thrusters. Extensible landing legs are all that would be required; once down, the ground crew can easily put wheels under the legs.

A primary advantage of the forward removable crew module with really powerful thrusters is that it offers unparalleled abort capabilities. Catastrophic launch abort? No problem; the thrusters blast you away from the exploding orbiter and then land propulsively well clear of the fireball. Meteor or debris strike in orbit that renders the orbiter unsuitable for re-entry (e.g, Columbia scenario)? Again, no problem; the crew module can detach and re-enter alone, using its underbelly shielding to aerobrake (ablatively, but at this point reuse is no longer the main concern) and touch down again on its thrusters.

And autonomous-return FH-style liquid-fueled boosters would be preferred to SRBs, but that's beside the point.

Edited February 11, 2016 by sevenperforce

[Emperor of the Titan Squid]

I like this design more,But have you considered using a catupult? also, if you have horizontal landing, you need wings, maybe folding.I suggest that this thread should have 3 phases, phase A which is now, and phase B, where the field will be narowed down and certain designs will be selected.Finally, in phase C we will build them in game.

[fredinno]

On February 11, 2016 at 6:06 AM, sevenperforce said:

With the high number of heat-resistant surfaces, re-entry should be easy. Yeah, it has a high aerodynamic load so that means heavier construction, but enhanced thrust should make up for it.

Bigger wings for what? It's not a lifting body.

"Takeoff and landing are horizonal".

[sevenperforce]

4 minutes ago, fredinno said:

"Takeoff and landing are horizonal".

Horizontal attitude, not horizontal direction.

[sevenperforce]

Here's the final render for what should be the ultimate (achievable) Space Shuttle concept.

I've pictured it with both the crew-carrying module and the payload module installed.

At a little over 90 meters in length, it's a whopper, nearly three times the length of the Space Shuttle orbiter:

It carries 42 linear aerospike engines. The two in the nose, pictured below, are only used at full throttle during takeoff and landing:

With an internal tank volume exceeding that of the Space Shuttle's external tank, it can carry a huge amount of fuel. The rounded-body form factor allows the tanks to form structural elements, reducing total weight.

The 30 forward main engines, eight on each centerbody sidewall and seven on each inner wing section, cause a vortex to form which travels down the length of the shuttle on each side:

The vortex on this side is counterclockwise; the vortex on the other side is opposite. In atmospheric flight, the pressure differential of the vortex causes air to be sucked in from below and above and added to the total flow.

The aft section contains two large aerospike engines angled directly back as well as eight additional wing-mounted engines which push against the vortex rotation to produce an evenly-directed propellant flow:

During takeoff, all downward-pointed engines (the rear wing-mounted engines and the centerbody engines) fire simultaneously with sufficient force to lift the shuttle straight up off the ground, air being pulled down between the wings and the centerbody to augment thrust. Then, the rear engines fire to propel the shuttle forward, while the vortex is initiated by throttling up the upward-pointed wing-mounted engines. This mode, while requiring additional thrust and a very specific design, allows for the safest possible takeoff and landing operation with maximal reusability.

The crew module contains its own fuel tank and six of the engines used for vertical takeoff, as well as four of the engines used for forward thrust. In any abort scenario, it can automatically detach from the rest of the craft and land propulsively. It is capable of independent re-entry.

This design uses the majority of its main propulsive engines for VTOL and only has two engines not used for forward propulsion. This, in combination with maximal thrust augmentation, enables a high T/W ratio as well as a low thrust specific fuel consumption.

So there you have it.

[Emperor of the Titan Squid]

For those who dont know, SERV was a space shuttle design from the 1960's.It was shaped like an apollo capsule, had an aerospike around the bottom, and a payload bay in the center.It would also have been able to carry payloads outside, and carry an orbiter called MURP, which would be a lifting body.

[Nothalogh]

22 hours ago, sevenperforce said:

Here's the final render for what should be the ultimate (achievable) Space Shuttle concept.

I've pictured it with both the crew-carrying module and the payload module installed.

At a little over 90 meters in length, it's a whopper, nearly three times the length of the Space Shuttle orbiter:

It carries 42 linear aerospike engines. The two in the nose, pictured below, are only used at full throttle during takeoff and landing:

With an internal tank volume exceeding that of the Space Shuttle's external tank, it can carry a huge amount of fuel. The rounded-body form factor allows the tanks to form structural elements, reducing total weight.

The 30 forward main engines, eight on each centerbody sidewall and seven on each inner wing section, cause a vortex to form which travels down the length of the shuttle on each side:

The vortex on this side is counterclockwise; the vortex on the other side is opposite. In atmospheric flight, the pressure differential of the vortex causes air to be sucked in from below and above and added to the total flow.

The aft section contains two large aerospike engines angled directly back as well as eight additional wing-mounted engines which push against the vortex rotation to produce an evenly-directed propellant flow:

During takeoff, all downward-pointed engines (the rear wing-mounted engines and the centerbody engines) fire simultaneously with sufficient force to lift the shuttle straight up off the ground, air being pulled down between the wings and the centerbody to augment thrust. Then, the rear engines fire to propel the shuttle forward, while the vortex is initiated by throttling up the upward-pointed wing-mounted engines. This mode, while requiring additional thrust and a very specific design, allows for the safest possible takeoff and landing operation with maximal reusability.

The crew module contains its own fuel tank and six of the engines used for vertical takeoff, as well as four of the engines used for forward thrust. In any abort scenario, it can automatically detach from the rest of the craft and land propulsively. It is capable of independent re-entry.

This design uses the majority of its main propulsive engines for VTOL and only has two engines not used for forward propulsion. This, in combination with maximal thrust augmentation, enables a high T/W ratio as well as a low thrust specific fuel consumption.

So there you have it.

That is madness, but it's my kind of madness 

[sevenperforce]

2 hours ago, Nothalogh said:

That is madness, but it's my kind of madness 

Madness?! This is SPARTA!

*Single-Propulsion Atmospheric Ram Terminal Ascender

 

[tater]

Crew:

 

Small payloads:

 

Large payloads should not waste throw weight with non-payload junk (an orbiter vehicle).

 

[Emperor of the Titan Squid]

How does it fly and land?Can we start phase B?

[Nothalogh]

5 hours ago, sevenperforce said:

Madness?! This is SPARTA!

*Single-Propulsion Atmospheric Ram Terminal Ascender

 

I like a lot of your design, but I think the VTOL and the cargo part are extraneous.

Focus on crew transfer and rapid turnaround 

[sevenperforce]

1 hour ago, Nothalogh said:

I like a lot of your design, but I think the VTOL and the cargo part are extraneous.

Focus on crew transfer and rapid turnaround 

The horizontal-attitude vertical takeoff is just a pipe dream, but the landing is pretty necessary. I don't like wings. Do ye not with wings what ye can accomplish with a short retro burn, the good book saith.

Cargo is probably not necessary either. 

On the other hand, an air-augmented SERV design would quite possibly be the smallest crew transfer shuttle we could reasonably build.

[Nothalogh]

40 minutes ago, sevenperforce said:

The horizontal-attitude vertical takeoff is just a pipe dream, but the landing is pretty necessary. I don't like wings. Do ye not with wings what ye can accomplish with a short retro burn, the good book saith.

Cargo is probably not necessary either. 

On the other hand, an air-augmented SERV design would quite possibly be the smallest crew transfer shuttle we could reasonably build.

I'm with you on all of that.

But son of a gun, would this make the XB-70 fly like a cessna

[fredinno]

22 hours ago, tater said:

Crew:

 

Small payloads:

 

Large payloads should not waste throw weight with non-payload junk (an orbiter vehicle).

 

Lifting bodies for cargo are good- if you have a LOT of stuff to bring down (asteroid mining)

[sevenperforce]

17 hours ago, Nothalogh said:

I'm with you on all of that.

But son of a gun, would this make the XB-70 fly like a cessna

Oh yeah.

Of course, it's not really a lifting body at all. There's a bit of induced hypersonic lift but nothing subsonic because it's vertically landed.

1 hour ago, fredinno said:

Lifting bodies for cargo are good- if you have a LOT of stuff to bring down (asteroid mining)

Yeah, for crew return, it's hard to imagine anything simpler, safer, or more reliable than a propulsively-landed capsule a la Dragon V2.

Only tangentially related...but had anyone ever proposed pairing two chemically reactive monopropellants for an SSTO design?

[DerekL1963]

2 hours ago, sevenperforce said:

Yeah, for crew return, it's hard to imagine anything simpler, safer, or more reliable than a propulsively-landed capsule a la Dragon V2.

o.0

It's trivial to imagine a simpler, safer, and more reliable system - just replace the Draco thrusters with solid fuel motors.   You've eliminated all the moving parts, all the pressurized components, and the corrosive, carcinogenic, and toxic propellants in one fell swoop.

[Nothalogh]

2 hours ago, sevenperforce said:

Only tangentially related...but had anyone ever proposed pairing two chemically reactive monopropellants for an SSTO design?

You mean like UDMH and Nitrogen Tetroxide?

Or something absolutely barbaric, like Tetraborane and Chlorine Trifluoride?

[RocketSquid]

I had an idea: Fully re-usable liquid-fueled booster. Uses linear aerospike engines at the base of the booster, and is a blended wing/lifting body, with various fuel tanks and some control systems inside. After detachment, it glides down with computer control, and either glides to a landing or deploys parachutes. If intended for SSTO, they could be equipped with a passively cooled TPS for re-entry.

[sevenperforce]

43 minutes ago, DerekL1963 said:

o.0

It's trivial to imagine a simpler, safer, and more reliable system - just replace the Draco thrusters with solid fuel motors.   You've eliminated all the moving parts, all the pressurized components, and the corrosive, carcinogenic, and toxic propellants in one fell swoop.

Hybrid-fueled, maybe. Solid-fueled motors can't restarted or throttled. And a hypergolic liquid-fueled option has much better Isp than a hybrid rocket. 

37 minutes ago, Nothalogh said:

You mean like UDMH and Nitrogen Tetroxide?

Or something absolutely barbaric, like Tetraborane and Chlorine Trifluoride?

Certainly the former. Though N2O4 isn't a monoprop...at least, not as far as I know. I was thinking of something more like H2O2 and hydrazine. 

Rockets are Carnot engines; they convert heat to velocity, with diminishing returns. If, however, two monopropellants were fired into each other at already-supersonic flow speed, their remaining chemical potential could be utilized at much higher efficiency. Basically a two-stage combustion process...an internally-burning scramjet.

4 minutes ago, RocketSquid said:

I had an idea: Fully re-usable liquid-fueled booster. Uses linear aerospike engines at the base of the booster, and is a blended wing/lifting body, with various fuel tanks and some control systems inside. After detachment, it glides down with computer control, and either glides to a landing or deploys parachutes. If intended for SSTO, they could be equipped with a passively cooled TPS for re-entry.

This is basically what I had as my first rendered concept earlier in this thread.