Rockwell International MRCC (Multi Role Common Core) spaceplane

[Vahe231991]

During the 1980s Rockwell International envisaged the MRCC (Multi Role Common Core) trans-atmospheric vehicle for the USAF to be used as a suborbital/orbital replacement for the F-111 fighter-bomber. The MRCC spaceplane would have been powered by one large rocket engine and two turbojets, with the option to remove and replace the turbojets with more rocket propellant and OMS-type engines. Unsurprisingly, the Rockwell International military TAV proposal was not proceeded with, given that the engine technology proposed for this spaceplane surely would have faced insurmountable technical and financial hurdles. This link can be consulted for technical data regarding the MRCC trans-atmospheric vehicle project:
https://www.secretprojects.co.uk/threads/rockwell-international-mrcc-multi-role-common-core-tav.1615/

[InterestedEngineer]

All air breathing SSTO systems suffer from a serious basic rocket equation problem:  Mass Ratio.

One can treat a launch to orbit as two conic sections:  Either 1 stage and 2nd stage (for TSTO), or atmosphere/vacuum for atmosphere breathing SSTO solutions.

Falcon 9 gets the second conic section started at 2.3km/sec at 65km altitude.  Similar for Starship/Booster.

A fantasy air breathing scramjet can get at most 3km/sec at 40km altitude (X-43 did it for 10 seconds).   so about 1.5x the energy.  (But most real-life proposals are less energy, topping out at Mach 5.).

The mass ratio of a large aircraft is on the order of 3 or less.  Usually a lot less.  Wings weigh a lot, as do the air breathing engines, landing gear, and airframe that ties them all together.  Which is great if you are flying around in an atmosphere, but terrible if you are trying to fly in a vacuum.

The mass ratio of the Falcon second stage is about 18 (6.5 for Starship).

There is no fuel that can make up for the lack of mass ratio in the second conic section.   The Isp of such a fuel would have to be 1.7x to make up for the difference in mass ratio of a Starship (or an Isp of 633) and 2.6x for Falcon 9 (an Isp of 910).  The only thing in that range is nuclear thermal, and that'll make the mass ratio even worse.

One could crank up the size of the atmosphere breathing SSTO in order to get a usable cargo mass, but then there would be no landing gear physically possible that would be able to land such a monster.

It amuses me every time I see fantasy drawings and even funding for startups that can't pass a very basic rocket equation scrutiny.

[RanulfC]

All air breathing SSTO systems suffer from a serious basic rocket equation problem:  Mass Ratio.

One can treat a launch to orbit as two conic sections:  Either 1 stage and 2nd stage (for TSTO), or atmosphere/vacuum for atmosphere breathing SSTO solutions.

Falcon 9 gets the second conic section started at 2.3km/sec at 65km altitude.  Similar for Starship/Booster.

A fantasy air breathing scramjet can get at most 3km/sec at 40km altitude (X-43 did it for 10 seconds).   so about 1.5x the energy.  (But most real-life proposals are less energy, topping out at Mach 5.).

The mass ratio of a large aircraft is on the order of 3 or less.  Usually a lot less.  Wings weigh a lot, as do the air breathing engines, landing gear, and airframe that ties them all together.  Which is great if you are flying around in an atmosphere, but terrible if you are trying to fly in a vacuum.

The mass ratio of the Falcon second stage is about 18 (6.5 for Starship).

There is no fuel that can make up for the lack of mass ratio in the second conic section.   The Isp of such a fuel would have to be 1.7x to make up for the difference in mass ratio of a Starship (or an Isp of 633) and 2.6x for Falcon 9 (an Isp of 910).  The only thing in that range is nuclear thermal, and that'll make the mass ratio even worse.

One could crank up the size of the atmosphere breathing SSTO in order to get a usable cargo mass, but then there would be no landing gear physically possible that would be able to land such a monster.

It amuses me every time I see fantasy drawings and even funding for startups that can't pass a very basic rocket equation scrutiny.

In context here this wasn't an "air-breathing SSTO" but an "near-SSTO with air-breathing engines" in that it was planned to be launched into near-orbit using large SRB and then using the air breathing engines after reentry as pretty much a 'normal' aircraft.

The version without any air-breathing engines removed them to make way for more propellant and better rocket engines so it could actually make orbit once the SRB burned out.

Randy

[john smith 19]

All air breathing SSTO systems suffer from a serious basic rocket equation problem:  Mass Ratio.

It's not an SSTO.

[john smith 19]

In context here this wasn't an "air-breathing SSTO" but an "near-SSTO with air-breathing engines" in that it was planned to be launched into near-orbit using large SRB and then using the air breathing engines after reentry as pretty much a 'normal' aircraft.

The version without any air-breathing engines removed them to make way for more propellant and better rocket engines so it could actually make orbit once the SRB burned out.

Randy

So basically an SRB powered sub-orbital vehicle, like a crewed Fractional Orbital Bombardment System.

If it's not burning propellent in its own engines on the way up then it's more akin to Buran or the X37b IE a payload than a plane. 

[Vahe231991]

Are there any technical specifications or extant Rockwell International project documents for the MRCC spaceplane in the Boeing archives?

[leovinus]

During the 1980s Rockwell International envisaged the MRCC (Multi Role Common Core) trans-atmospheric vehicle for the USAF to be used as a suborbital/orbital replacement for the F-111 fighter-bomber. The MRCC spaceplane would have been powered by one large rocket engine and two turbojets, with the option to remove and replace the turbojets with more rocket propellant and OMS-type engines. Unsurprisingly, the Rockwell International military TAV proposal was not proceeded with, given that the engine technology proposed for this spaceplane surely would have faced insurmountable technical and financial hurdles. This link can be consulted for technical data regarding the MRCC trans-atmospheric vehicle project:
https://www.secretprojects.co.uk/threads/rockwell-international-mrcc-multi-role-common-core-tav.1615/

This images are from Markus Lindroos website specifically this link
https://web.archive.org/web/20131103130133/http://www.pmview.com/spaceodysseytwo/spacelvs/sld054.htm
That is Section 5 here
https://web.archive.org/web/20131225010025/http://www.pmview.com/spaceodysseytwo/spacelvs/
Fun projects. You might like the 4 part articles here as well
https://www.thespacereview.com/article/4161/1

[leovinus]

Are there any technical specifications or extant Rockwell International project documents for the MRCC spaceplane in the Boeing archives?

Probably. The hurdles include (1) finding the correct document titles, contract numbers, etc (2) Asking politely at Boeing public relations whether they can help find stuff in their archives. Sometimes that even works

As an example, there is this one below. Note that Boeing reports start with something like D2- or D7- or in this case D180-
With a bunch of sleuthing you will find references like

Boeing Aerospace Company: "Advanced Space Lift Study for Mission Analysis on Future Military Space Activities,"—A.F. Contract F04701-75-C-0208, Boeing Document D180-18856-1.

Swegle, A. R., "Advanced Space Transportation System Research 1974 IR&D Summary," Boeing Document D180-18622-1, 1975.

and there will be more with the details you asked about.

Anyway, this document below has a B-2 concept that is also discussed at https://www.thespacereview.com/article/4161/1

Final report BOEING TRANSATMOSPHERIC VEHICLE (TAV) CONCEPTS DEFINITION (PHASE I)
Battelle Columbus Laboratories (Subcontract No. A-3089(6697)-288)
USAF Contract No. F33615-83-C-0132, Task 6
December 22, 1983 Report Number D180-27669-4
> The study requested The Boeing Company to describe two or more Transatmospheric Vehicle (TAV) concepts that could provide 5,000 lb to 30,000 lb in low Earth orbit utilizing horizontal takeoff (HT0). A brief list of system requirements and goals were defined in the statement of work.
https://apps.dtic.mil/sti/pdfs/ADB216503.pdf
https://apps.dtic.mil/sti/citations/ADB216503

[john smith 19]

Final report BOEING TRANSATMOSPHERIC VEHICLE (TAV) CONCEPTS DEFINITION (PHASE I)
Battelle Columbus Laboratories (Subcontract No. A-3089(6697)-288)
USAF Contract No. F33615-83-C-0132, Task 6
December 22, 1983 Report Number D180-27669-4
> The study requested The Boeing Company to describe two or more Transatmospheric Vehicle (TAV) concepts that could provide 5,000 lb to 30,000 lb in low Earth orbit utilizing horizontal takeoff (HT0). A brief list of system requirements and goals were defined in the statement of work.
https://apps.dtic.mil/sti/pdfs/ADB216503.pdf
https://apps.dtic.mil/sti/citations/ADB216503

Good finds.

While one of the reports is dated 1996 it's clear they lifted a big chunk of it from the Boeing RASV studies of the early 80's where they tried to convince the USAF they could do an assisted SSME based SSTO for a fixed price contract of $1Bn.