Space shuttle turbofans for ferry flight

[archipeppe]

Here it is an updated (and also upgraded) version of my original ABPS artwork.

 

[Byeman]

And IIRC most planes cannot start the engines in flight at above 30,000ft.

So that eliminates airfield diversion, since the vehicle is already on the HAC at 5 minutes.
As for go around, if the vehicle makes it to the HAC, it doesn't need to worry about being short of energy.
What do you thing the weight of engines, structure, wiring, controls, fuel, etc would do to the size, utility and operation of Dream Chaser or X-37? The chances of building another shuttle size orbiter are slim to nil.

 

[Owens Z]

Nope, it never will make sense. See X-37, Dream Chaser. It really doesn't increase safety. And regardless of jet engines, the entry is still going to take the vehicle to the planned landing site area since the engines wouldn't operate until below 60kft which is less than 5 minute before landing.

So that eliminates airfield diversion, since the vehicle is already on the HAC at 5 minutes. As for go around, if the vehicle makes it to the HAC, it doesn't need to worry about being short of energy. What do you thing the weight of engines, structure, wiring, controls, fuel, etc would do to the size, utility and operation of Dream Chaser or X-37? The chances of building another shuttle size orbiter are slim to nil.

I'm not following you, Byeman—unpowered spaceplanes necessarily have to glide to touchdown, and spaceplanes with air-breathing engines necessarily have to glide to touchdown?

According to Dennis R. Jenkins's magisterial reference, the average for the Shuttle flight campaign was for the orbiter to pass 49,000 feet and Mach 1 approximately 30 miles out from the intended runway (Space Shuttle 4th Ed Vol III p13). Any pilot seeing black thunderclouds gather ahead with little warning (as is common in central Florida) will want options if at all possible. That the unpowered Shuttle orbiter with no options (except a chancy bailout from STS-26 onward) glided to landings with surprisingly ease is a historical fact. But again, many believe that rolling the dice would inevitably have resulted in bad news someday.

Today we can and should do better than the Space Shuttle's 1970s design and tech. Byeman's prophecy that diversion will forever be impractical for a spaceplane is unconvincing.

 

[Owens Z]

Here it is an updated (and also upgraded) version of my original ABPS artwork.

Excellent artwork of a prospective jet-powered Shuttle orbiter; thank you Archipeppe. Those look like turbojets (J57s?) rather than high-bypass turbofans. Air-breathing engines (for self-ferry and/or to allow go-arounds on landing) were seriously considered when the Shuttle orbiter was designed in the 1970s, but the decision was finally made (with misgivings) not to include those. It turned out that unpowered landings and the two 747s for ferry duty were adequate. For such air-breathing engines to make sense, they would really need to be designed in from the start, not added later as a modification to an already tight design. We will see what the future brings.

 

[publiusr]

Excellent artwork of a prospective jet-powered Shuttle orbiter; thank you Archipeppe. Those look like turbojets (J57s?) rather than high-bypass turbofans.
We will see what the future brings.

YJ-93 turbojets already had to operate at high-altitudes and higher temperatures...twice the thrust as J-57. Even if jets are not strictly needed if coming back to an airstrip near the launch site---the point is that you don't have to.

Instead of underwing pods, perhaps engines could be atop the wing root. If nothing else, simple *ramjets* could ignite on orbital return, so perhaps you could re-enter over water, and fly a Buran like orbiter to a wider range of airfields... meaning you may not have to re-enter over populated areas deadstick.

THEN mount pods with full jets for self ferry.

Byeman shoehorns a couple of items inside Delta II shrouds—and he thinks he knows everything.
Pay no attention.

 

[Scott Kenny]

I'm not following you, Byeman—unpowered spaceplanes necessarily have to glide to touchdown, and spaceplanes with air-breathing engines necessarily have to glide to touchdown?

According to Dennis R. Jenkins's magisterial reference, the average for the Shuttle flight campaign was for the orbiter to pass 49,000 feet and Mach 1 approximately 30 miles out from the intended runway (Space Shuttle 4th Ed Vol III p13). Any pilot seeing black thunderclouds gather ahead with little warning (as is common in central Florida) will want options if at all possible. That the unpowered Shuttle orbiter with no options (except a chancy bailout from STS-26 onward) glided to landings with surprisingly ease is a historical fact. But again, many believe that rolling the dice would inevitably have resulted in bad news someday.

Today we can and should do better than the Space Shuttle's 1970s design and tech. Byeman's prophecy that diversion will forever be impractical for a spaceplane is unconvincing.

Because you're only going to be able to start whatever jet engines you have below 30,000ft. Which means ~20 miles or less from the landing strip.

 

[Owens Z]

And IIRC most planes cannot start the engines in flight at above 30,000ft.

Because you're only going to be able to start whatever jet engines you have below 30,000ft. Which means ~20 miles or less from the landing strip.

No. Byeman asks us to add stock airliner engines to the Shuttle orbiter now (well, in 2011, when the Shuttle was last flying), points out problems with balance, engine start at high altitude, jury-rigged fuel lines, etc., and then maintains that since that would be unworkable, the very concept of powered flyback is forever unworkable. Tendentious. The true thought experiment is, of course, to imagine purposely designed flyback/ferry engines being included in the orbiter design from the ground up (as was seriously considered in the 1970s). Or to plan air-breathing engines in a future spaceplane.

In the late 1950s, 49,000 feet was about the altitude that a U-2 would descend to for J57 restart after a flameout at its 70,000+ operating altitude. NASA's two early-model B-52s (eight J57s) could maintain level flight at over 50,000 feet. So designing appropriate flyback engines for the Space Shuttle orbiter in the 1970s that would start at 49,000 when it became subsonic was hardly an impossibility. Even more capable flyback/ferry engines could be designed today. And in another twenty years, who knows what will be doable?

 

[Owens Z]

YJ-93 turbojets already had to operate at high-altitudes and higher temperatures...twice the thrust as J-57. Even if jets are not strictly needed if coming back to an airstrip near the launch site---the point is that you don't have to...

Agreed, the YJ93 turbojet worked well at over Mach 3 in the two XB-70s sixty years ago (and was adequate for subsonic ferry flights). Supersonic operating speeds would allow powered flight for a reentering spaceplane farther from the runway. The technology was there in the 1970s (but perhaps not the budget).

 

[NMaude]

Agreed, the YJ93 turbojet worked well at over Mach 3 in the two XB-70s sixty years ago (and was adequate for subsonic ferry flights). Supersonic operating speeds would allow powered flight for a reentering spaceplane farther from the runway. The technology was there in the 1970s (but perhaps not the budget).

What about the GE4 turbojet developed for The Boeing 2707-200 SST?

 

[Scott Kenny]

In the late 1950s, 49,000 feet was about the altitude that a U-2 would descend to for J57 restart after a flameout at its 70,000+ operating altitude. NASA's two early-model B-52s (eight J57s) could maintain level flight at over 50,000 feet. So designing appropriate flyback engines for the Space Shuttle orbiter in the 1970s that would start at 49,000 when it became subsonic was hardly an impossibility. Even more capable flyback/ferry engines could be designed today. And in another twenty years, who knows what will be doable?

There's a significant difference between "low enough to restart an already-spinning engine" and "low enough to windmill-start a stalled engine from 0 rpm"

 

[Byeman]

According to Dennis R. Jenkins's magisterial reference, the average for the Shuttle flight campaign was for the orbiter to pass 49,000 feet and Mach 1 approximately 30 miles out from the intended runway (Space Shuttle 4th Ed Vol III p13). Any pilot seeing black thunderclouds gather ahead with little warning (as is common in central Florida) will want options if at all possible. That the unpowered Shuttle orbiter with no options (except a chancy bailout from STS-26 onward) glided to landings with surprisingly ease is a historical fact. But again, many believe that rolling the dice would inevitably have resulted in bad news someday.

It was't 30 miles "out", it was 30 miles from landing. The orbiter would be entering the heading alignment circle/cone (HAC) to turn to the runway (the 30 miles includes flying around the HAC). It has already been committed to the intended runway when it enters the HAC.
When you are at the landing site and want to watch a shuttle landing, you don't look to the horizon to find the orbit, you look straight up.
There is no ability to divert. Anyways, where is it going to divert to?

 

[Byeman]

Today we can and should do better than the Space Shuttle's 1970s design and tech. Byeman's prophecy that diversion will forever be impractical for a spaceplane is unconvincing.

No, not with chemically powered jet engines. Too much mass for no real benefit.

 

[Byeman]

Instead of underwing pods, perhaps engines could be atop the wing root. If nothing else, simple *ramjets* could ignite on orbital return, so perhaps you could re-enter over water, and fly a Buran like orbiter to a wider range of airfields... meaning you may not have to re-enter over populated areas deadstick.

With what fuel? Going to carry all that fuel up and back down?

What does Buran have to do with it? Again, large cargo carrying orbiters without engines make no sense.* Either use a small spaceplane for crew (like Dream Chaser or X-37C) or a regular fairing for large cargo. There is no need or economic sense for a large winged reusable "fairing" that lands on a runway that also can carry crew.

* what requirements would drive a need for such a vehicle and what is the business case?

 

[Atomic Coyote]

Two YJ93s (or similar) are going to weigh about 5 tons for the engines alone, add in another 5 tons of fuel and you get enough gas to run them for about 20 minutes (rough calc). Add in whatever doohickey you're using to deploy them into the airstream after the hypersonic portion of reentry, structural reinforcements, other additional systems, etc. and you'd be lucky if they Shuttle has enough payload left to deploy a sputnik into orbit.

 

[Byeman]

Agreed, the YJ93 turbojet worked well at over Mach 3 in the two XB-70s sixty years ago (and was adequate for subsonic ferry flights). Supersonic operating speeds would allow powered flight for a reentering spaceplane farther from the runway. The technology was there in the 1970s (but perhaps not the budget).

It wasn't the fiscal budget, it was the mass budget. J57 engines weighed 5,000lb. 5 were planned for self ferry. That is 25,000lb, almost 1/2 the payload capacity of the shuttle and that doesn't include mounting structure, fuel, tanks, wiring and controls.

 

[publiusr]

Two YJ93s (or similar) are going to weigh about 5 tons for the engines alone, add in another 5 tons of fuel and you get enough gas to run them for about 20 minutes (rough calc).

That's why the concept works better with no SSME's in the boat-tail. Ramjets would weigh less of course...perhaps helping to warm up small turbojets next door. Not having three heavy RS-25s helps.

Design a good non-glider orbiter that can function as a true airplane, and scale up the rest of the launch vehicle stack to match. However much the space plane weighs--that's the LV payload. Have that do Boostback, have elonerons... whatever...if you must

This way, no scramjet is needed....no Star Raker. You have a good jet that just happens to be space worthy.

 

[Byeman]

That's why the concept works better with no SSME's in the boat-tail. Ramjets would weigh less of course...perhaps helping to warm up small turbojets next door. Not having three heavy RS-25s helps.

No, it doesn't work at all. Cost matters now. There is no business case that supports such a vehicle. There is no reason to have a large orbiter type vehicle that isn't part of the launch vehicle. It is just a very expensive crewed reusable payload fairing both in development and operations.

Design a good non-glider orbiter that can function as a true airplane,

There is no such thing.

 

[Owens Z]

It was't 30 miles "out", it was 30 miles from landing. The orbiter would be entering the heading alignment circle/cone (HAC) to turn to the runway (the 30 miles includes flying around the HAC)...

Byeman, I spoke with Mr Jenkins, and he confirms that when he wrote in his book that the reentering Space Shuttle orbiter went subsonic "about 30 miles from the runway", this is a measure of the actual traverse of the vehicle as it turned and banked around the heading alignment cone. Not a measure of a straight line between the spot where the orbiter went subsonic and the runway threshold, as I had mistakenly thought. Such a straight line would necessarily be considerably less than 30 miles. You were right.

It has already been committed to the intended runway when it enters the HAC...

The Shuttle orbiter was already committed to the intended runway after it was halfway through its OMS rocket burn on the other side of the planet. Risky.

When you are at the landing site and want to watch a shuttle landing, you don't look to the horizon to find the orbit, you look straight up...

You indulge in hyperbole (it wasn't a Stuka), but yes, my line of sight to a Shuttle orbiter closer than thirty miles away at circa 49,000 ft altitude would indeed be well above my horizon. A notably steep glidepath, as Scott Kenny reminded us.

"We're in the pipe, 5 by 5"

View: https://www.youtube.com/watch?v=8vESxCZe0HA

 

[Byeman]

Byeman, I spoke with Mr Jenkins, and he confirms that when he wrote in his book

I used actual Shuttle documentation for my reference.

The Shuttle orbiter was already committed to the intended runway after it was halfway through its OMS rocket burn on the other side of the planet. Risky.

Diversion to Orlando, Jacksonville, West Palm, etc could happen after OMS burn

You indulge in hyperbole (it wasn't a Stuka), but yes, my line of sight to a Shuttle orbiter closer than thirty miles away at circa 49,000 ft altitude would indeed be well above my horizon. A notably steep glidepath, as Scott Kenny reminded us.

No hyperbole. I was at the SLF for 20 or so landings, Edwards for a few and at KSC or surrounding area for another 30 or so. On a few of them, especially those with a HAC of greater than 180 degrees, we could see yaw RCS firings (smoke puffs) and many we saw it before it entered the HAC

 

[blackstar]

Byeman, I spoke with Mr Jenkins, and he confirms that when he wrote in his book that the reentering Space Shuttle orbiter went subsonic "about 30 miles from the runway", this is a measure of the actual traverse of the vehicle as it turned and banked around the heading alignment cone. Not a measure of a straight line between the spot where the orbiter went subsonic and the runway threshold, as I had mistakenly thought. Such a straight line would necessarily be considerably less than 30 miles. You were right.

He worked on the shuttle program. So he knows a bit about it.

 

[Archibald]

I'd like to ask... was there any kind of contingency plan to fire the OMS pods during a landing, in case the Shuttle fell a little short of the runway ? (provided of course the pods had some propellant left)

 

[Byeman]

I'd like to ask... was there any kind of contingency plan to fire the OMS pods during a landing, in case the Shuttle fell a little short of the runway ? (provided of course the pods had some propellant left)

Never. The nozzles were sized for vacuum, they would collapse. Plus the T/W was less than 0.05.

 

[Scott Kenny]

Never. The nozzles were sized for vacuum, they would collapse. Plus the T/W was less than 0.05.

wasn't the OMS translate burn 1m/s? A couple of bumps would likely be just enough to get to the runway threshold.

 

[publiusr]

It isn’t as if that couldn’t be beefed up.. OK-92 style. That used kerosene, which lends itself to, say, ramjet use.

 

[Byeman]

wasn't the OMS translate burn 1m/s? A couple of bumps would likely be just enough to get to the runway threshold.

Not with a T/W of .05, it would take too long.

 

[Scott Kenny]

Not with a T/W of .05, it would take too long.

Even the big OMS rockets? the ones used for the deorbit burn?

 

[Byeman]

Even the big OMS rockets? the ones used for the deorbit burn?

They aren't big. T/W of >0.05. 12klb thrust vs 250klb mass

 

[Owens Z]

Two YJ93s (or similar) are going to weigh about 5 tons for the engines alone, add in another 5 tons of fuel and you get enough gas to run them for about 20 minutes (rough calc). Add in whatever doohickey you're using to deploy them into the airstream after the hypersonic portion of reentry, structural reinforcements, other additional systems, etc. and you'd be lucky if they Shuttle has enough payload left to deploy a sputnik into orbit.

It wasn't the fiscal budget, it was the mass budget. J57 engines weighed 5,000lb. 5 were planned for self ferry. That is 25,000lb, almost 1/2 the payload capacity of the shuttle and that doesn't include mounting structure, fuel, tanks, wiring and controls.

There are hidden assumptions here, perhaps unwarranted.

Regarding air-breathing flyback engines, I point out to readers that while the Shuttle orbiter's payload bay was designed for 65,000 lbs (29.5 tonnes), the actual heaviest payload ever launched was 54,006 lbs (24.5t), on STS-51 in 1993, and the mean payload over the Shuttle flight campaign was only 15.9 tonnes (Jenkins, Space Shuttle 4th Ed Vol III pp406-409). Payload is good to have. Seen in hindsight, it turned out there was margin for other good things to have. Academic for the retired Space Shuttle—yet lessons learned are of interest for when a future spaceplane is designed.

I am unfamiliar with the specs of the particular self-ferry Shuttle orbiter version that Archipeppe has skillfully illustrated. I know that many different self-ferry configurations were explored in the 1970s. For those several that put a specially designed plug-in module inside the payload bay when needed, it would seem that if the module's total weight (including jet fuel) came to less than 65,000 lbs, then it would have worked, however clumsily. (Before somebody interjects that the existing payload bay was not stressed for this or that—yes, yes, the orbiter design would have had to incorporate self-ferrying from the start, as I have always stipulated.) I agree that for ferry flights, NASA's two early model 747s proved perfectly adequate.

 

[Owens Z]

He worked on the shuttle program. So he knows a bit about it.

Blackstar, your message is unclear, but if "he" refers to Byeman instead of Space Shuttle program veteran Dennis R. Jenkins, then this is welcome news. Such experienced authorities keep our technical discussions here on Secret Projects Forum honest.

 

[Owens Z]

A USENET message last week from the noted Henry Spencer on "a cautionary tale about relying on glide landings with no go-around capability" may be of relevance here.

The YouTube video by Scott Manley "The Space Shuttle That Didn't Reach The Runway - Why Did Atlantis Land Short on STS-37?" was inspired by a blog posting: < https://waynehale.wordpress.com/2024/03/10/putting-atlantis-at-risk/ >. Spencer writes that the "posting is a detailed account of how, at the end of Shuttle flight STS-37 [in 1991], orbiter Atlantis managed to land 3000 ft short of the desired touchdown point and 600 ft short of the runway threshold. No harm done, because the landing was on an Edwards [AFB] lakebed runway, where the threshold is just a semi-arbitrary line of paint on the lakebed. It might have been okay even on a hard-surface runway, because to be deemed acceptable for Shuttle landings (even for emergency use only), a runway had to have a paved underrun area as a hedge against such mishaps. But the margins were thin that day, and changes were [later] made to try to prevent any repetition. The blog author, Wayne Hale, was the flight controller who cleared Atlantis for that descent and landing. None of his choices looked good. The weather just wasn't cooperating, not only at the primary landing sites but even at a lot of the emergency sites, and the orbiter was already one day into its postponed-landing reserve supplies, and the forecasts for the next day didn't look much better. Sometimes the atmosphere is not your friend."

STS-37's unpowered glide landing turned out to be okay. But as I said: risky.

 

[blackstar]

Blackstar, your message is unclear, but if "he" refers to Byeman instead of Space Shuttle program veteran Dennis R. Jenkins, then this is welcome news. Such experienced authorities keep our technical discussions here on Secret Projects Forum honest.

Both of them did.

 

[Owens Z]

I'd like to ask... was there any kind of contingency plan to fire the OMS pods during a landing, in case the Shuttle fell a little short of the runway ? (provided of course the pods had some propellant left)

Never. The nozzles were sized for vacuum, they would collapse. Plus the T/W was less than 0.05.

wasn't the OMS translate burn 1m/s? A couple of bumps would likely be just enough to get to the runway threshold.

It isn’t as if that couldn’t be beefed up.. OK-92 style. That used kerosene, which lends itself to, say, ramjet use.

Not with a T/W of .05, it would take too long.

Even the big OMS rockets? the ones used for the deorbit burn?

They aren't big. T/W of >0.05. 12klb thrust vs 250klb mass

The Space Shuttle orbiter's RCS rockets provided attitude control during reentry, with the last active units, the aft yaw primary thrusters, shut down around 45,000 feet (roughly one-seventh sea level pressure). Dynamic pressure in the thickening air below that altitude would overwhelm the relatively feeble thrust, so firing became pointless. The featherweight force appropriate for a spaceplane's movement in microgravity is of no consequence in the troposphere. In the same sense, while in orbit the spindly Canadarm manipulated 12-ton modules from the Shuttle payload bay with ease, in the factory Canadarm was unable to lift itself off the floor.

In principle, the Orbital Maneuvering System's two rocket motors could have been beefed up during the 1970s design process to any arbitrary size, to provide rocket-powered landings for the orbiter rather than the glide landings actually chosen. Yet this seems inelegant. For a future spaceplane, just like was decided for the Saunders-Roe SR.53 rocket fighter (and planned SR.177), a modest air-breathing jet engine added to the vehicle would be better than rocket power or unpowered glide for bringing her safely home (at flight idle), and (at full thrust) go-around or diversion when necessary. Then the OMS can be efficiently sized for space use only, as it was in Space Shuttle.

 

[publiusr]

I think it is good to have margin...we know X-37 can remain in orbit a long time with hypergolics...but kerosene is more plentiful on the ground, and oxygen allows life support.

Not having a tail full of dead-mass SSMEs really opens things up. Getting that and most of the eggshell tankage outside of the airframe makes for an aircraft less of a beached whale.

 

[NMaude]

Getting that and most of the eggshell tankage outside of the airframe makes for an aircraft less of a beached whale.

Beached whale? More like a brick with wings and a tail-fin.

 

[publiusr]

Imagine if the orbiter ate its External Tank
That was the Rockwell X-33 path.

By keeping the rocketry part needed to achieve orbit outside the airframe--you don't have to fly just one kind of orbiter. One might be less or a brick, with a more streamlined crew compartment.

There is a wonderful quote on page 94 of Jenkins' book called LOCKHEED SECRET PROJECTS--INSIDE THE SKUNK WORKS, a quote about how the VentureStar design morphed from internal payload bays to a hump, and finally the payload:

"had been moved completely out of the vehicle and into a piggyback container. This may not be detrimental since it would allow the vehicle to carry payloads of almost any given size and shape, at least within some aerodynamic and thermal considerations."

--thus my advocacy of parallel staging and piggyback payload mount of the modular Buran approach.

As for the unmanned rocket core once shed...have that come back like Starship...use it as a wet workshop...expend it.. whatever. At least it's parasite mass doesn't interfere with the flight dynamics of the space-plane.

It makes self-ferry MUCH easier.

Fly it at air shows when not hooked to a booster.

 

[Scott Kenny]

Beached whale? More like a brick with wings and a tail-fin.

Bricks are more aerodynamic than the Space Shuttle.

 

[Byeman]

In principle, the Orbital Maneuvering System's two rocket motors could have been beefed up during the 1970s design process to any arbitrary size, to provide rocket-powered landings for the orbiter rather than the glide landings actually chosen. Yet this seems inelegant. For a future spaceplane, just like was decided for the Saunders-Roe SR.53 rocket fighter (and planned SR.177), a modest air-breathing jet engine added to the vehicle would be better than rocket power or unpowered glide for bringing her safely home (at flight idle), and (at full thrust) go-around or diversion when necessary. Then the OMS can be efficiently sized for space use only, as it was in Space Shuttle.

wrong. Use of the OMS has multiple issue:
1. Low thrust
2. Inadequate propellant
3. Not designed for atmospheric use.

Jet engines are more inelegant when nothing works better.
A "modest" jet engine would not enable go around
Again, no such thing as a diversion for landings like this.

 

[Byeman]

I think it is good to have margin...we know X-37 can remain in orbit a long time with hypergolics...but kerosene is more plentiful on the ground, and oxygen allows life support.

Meaningless points. Hypergols availability is not an issue. Using GOX is not an advantage,

Not having a tail full of dead-mass SSMEs really opens things up. Getting that and most of the eggshell tankage outside of the airframe makes for an aircraft less of a beached whale.

Wrong. What is the point of a large orbiter with no main engines? The object is to reduce costs. It does the opposite by increasing costs by turning the orbiter into just an expensive payload fairing and throwing away the engines. There are bettter ways to design for payload fairing reuse.

The Soviets designed Buran Energia under false premises because they didn't think the shuttle existed to reduce costs. When you only want to deliver warheads, then reducing costs and saving the engines doesn't matter.

 

[Byeman]

Imagine if the orbiter ate its External Tank
That was the Rockwell X-33 path.

Which was another wrong path.

By keeping the rocketry part needed to achieve orbit outside the airframe--you don't have to fly just one kind of orbiter. One might be less or a brick, with a more streamlined crew compartment.

that's the problem. A crew compartment is not needed. This is a launch vehicle.

There is a wonderful quote on page 94 of Jenkins' book called LOCKHEED SECRET PROJECTS--INSIDE THE SKUNK WORKS, a quote about how the VentureStar design morphed from internal payload bays to a hump, and finally the payload:

"had been moved completely out of the vehicle and into a piggyback container. This may not be detrimental since it would allow the vehicle to carry payloads of almost any given size and shape, at least within some aerodynamic and thermal considerations."

--thus my advocacy of parallel staging and piggyback payload mount of the modular Buran approach.

You almost had it right and then get it completely wrong in the last sentence.
VentureStar reused the tankage and engines and had a cheap payload container. It is nothing like the Buran, which threw away the tanks and engines and used an expensive reusable payload fairing.
So your "advocacy' of parallel staging and piggyback payload mount is based on failed logic.

As for the unmanned rocket core once shed...have that come back like Starship...use it as a wet workshop...expend it.. whatever. At least it's parasite mass doesn't interfere with the flight dynamics of the space-plane.

The point is to make space launch cheaper and not just fly a space planes.

You keep trying to advocate vehicles without a purpose. These days, cost is the first design consideration and then lift capability.
Launch vehicles are not Lego pieces. Boosters and upperstages are designed to be paired to increase efficiency and to reduce costs. A space plane will never be part of a cost effective launch vehicle.
Pieces are not thrown together to make a rocket, unless you only concerned with a jobs program.

 

[publiusr]

The point is to make space launch cheaper and not just fly a space plane.

Separation of function allow both--Falcon and X-37 were both flown back... separately.

If X-37 ate Falcon, then it would be the Rockwell X-33 that you called the wrong path.

It was at least more conventional than DC-X or VentureStar.

Maybe you could get a winged-strap-on out of that at least

Was everyone who suggested jets on winged rockets wrong and you correct?