The Rocket Motor of the Future Breathes Air Like a Jet Engine

"The two men arrived at the airfield before dawn to set up the test stand for a
prototype of their air-breathing rocket engine, a new kind of propulsion system
that is a cross between a rocket motor and a jet engine. They call their unholy
creation Fenris, and Davis believes that it’s the only way to make getting to
space cheap enough for the rest of us. While a conventional rocket engine must
carry giant tanks of fuel and oxidizer on its journey to space, an air-breathing
rocket motor pulls most of its oxidizer directly from the atmosphere. This means
that an air-breathing rocket can lift more stuff with less propellant and
drastically lower the cost of space access—at least in theory.

The idea to combine the efficiency of a jet engine with the power of a rocket
motor isn’t new, but historically these systems have only been combined in
stages. Virgin Galactic and Virgin Orbit, for example, use jet aircraft to carry
conventional rockets several miles into the atmosphere before releasing them for
the final leg of the journey to space. In other cases, the order is reversed.
The fastest aircraft ever flown, NASA’s X-43, used a rocket engine to provide an
initial boost before an air-breathing hypersonic jet engine—known as a scramjet—
took over and accelerated the vehicle to 7,300 mph, nearly 10 times the speed of
sound.

But if these staged systems could be rolled up into one engine, the huge
efficiency gains would dramatically lower the cost of getting to space. “The
holy grail is a single-stage-to-orbit vehicle where you just take off from a
runway, fly into space, and come back and reuse the system,� says Christopher
Goyne, director of the University of Virginia’s Aerospace Research Laboratory
and an expert in hypersonic flight."

See:

https://www.wired.com/story/the-rock...-a-jet-engine/

On 6/28/20 9:54 AM, JF Mezei wrote:
On 2020-06-27 18:19, wrote:

space cheap enough for the rest of us. While a conventional rocket engine must
carry giant tanks of fuel and oxidizer on its journey to space, an air-breathing
rocket motor pulls most of its oxidizer directly from the atmosphere.


*Most* of its oxydizer?
Until what altitude is there enough air to run a rocket engine?
How long out of the roughly 8 minutes for first stage engine firing does
it take to reach that altitude?

Could such an engine be efficent when what it breathes in is 80%
nitrogen and 20% oxygen?

Would such an engine have both a LOX turbopump as we know it, and a
separate one that pushes gaseous air into combustion chamber? (with the
LOX turbopump activated once a certain altiutude is reached.

Is it theoretically possible to design the injectors and combustion
chamber to handle both gaseious pure oxygen at high pressure (after
pre-burner) and gaseous mix of nitrogen and oxygen (air) ?





there is no future for rocket motors, after PNN will be patented all
rocket motors will look like toys.

On Sunday, June 28, 2020 at 3:54:25 AM UTC-4, JF Mezei wrote:
On 2020-06-27 18:19, wrote:

space cheap enough for the rest of us. While a conventional rocket engine must
carry giant tanks of fuel and oxidizer on its journey to space, an air-breathing
rocket motor pulls most of its oxidizer directly from the atmosphere.


*Most* of its oxydizer?
Until what altitude is there enough air to run a rocket engine?
How long out of the roughly 8 minutes for first stage engine firing does
it take to reach that altitude?

Could such an engine be efficent when what it breathes in is 80%
nitrogen and 20% oxygen?

Would such an engine have both a LOX turbopump as we know it, and a
separate one that pushes gaseous air into combustion chamber? (with the
LOX turbopump activated once a certain altiutude is reached.

Is it theoretically possible to design the injectors and combustion
chamber to handle both gaseious pure oxygen at high pressure (after
pre-burner) and gaseous mix of nitrogen and oxygen (air) ?

If you read the article, everyone of your questions was addressed.

On Sunday, June 28, 2020 at 11:49:29 PM UTC-4, Doctor Who wrote:
On 6/28/20 9:54 AM, JF Mezei wrote:
On 2020-06-27 18:19, wrote:

space cheap enough for the rest of us. While a conventional rocket engine must
carry giant tanks of fuel and oxidizer on its journey to space, an air-breathing
rocket motor pulls most of its oxidizer directly from the atmosphere.


*Most* of its oxydizer?
Until what altitude is there enough air to run a rocket engine?
How long out of the roughly 8 minutes for first stage engine firing does
it take to reach that altitude?

Could such an engine be efficent when what it breathes in is 80%
nitrogen and 20% oxygen?

Would such an engine have both a LOX turbopump as we know it, and a
separate one that pushes gaseous air into combustion chamber? (with the
LOX turbopump activated once a certain altiutude is reached.

Is it theoretically possible to design the injectors and combustion
chamber to handle both gaseious pure oxygen at high pressure (after
pre-burner) and gaseous mix of nitrogen and oxygen (air) ?





there is no future for rocket motors, after PNN will be patented all
rocket motors will look like toys.

There is also no future for trolls named after fictional scifi characters.

On 6/29/20 1:42 PM, Dean Markley wrote:
On Sunday, June 28, 2020 at 11:49:29 PM UTC-4, Doctor Who wrote:
On 6/28/20 9:54 AM, JF Mezei wrote:
On 2020-06-27 18:19, wrote:

space cheap enough for the rest of us. While a conventional rocket engine must
carry giant tanks of fuel and oxidizer on its journey to space, an air-breathing
rocket motor pulls most of its oxidizer directly from the atmosphere.


*Most* of its oxydizer?
Until what altitude is there enough air to run a rocket engine?
How long out of the roughly 8 minutes for first stage engine firing does
it take to reach that altitude?

Could such an engine be efficent when what it breathes in is 80%
nitrogen and 20% oxygen?

Would such an engine have both a LOX turbopump as we know it, and a
separate one that pushes gaseous air into combustion chamber? (with the
LOX turbopump activated once a certain altiutude is reached.

Is it theoretically possible to design the injectors and combustion
chamber to handle both gaseious pure oxygen at high pressure (after
pre-burner) and gaseous mix of nitrogen and oxygen (air) ?





there is no future for rocket motors, after PNN will be patented all
rocket motors will look like toys.

There is also no future for trolls named after fictional scifi characters.



your contemptuous behavior will not do you any good.

It took forever for this article to finally getting around to mentioning
the technological leader, the Sabre engine from Reaction Engines.
Almost no mention of how a "Fenris" engine works. You have to follow the
link "Fenris" which takes you to a non-patent office page of what
appears to be a patent application, but isn't? It does look different in
fundamental design from the Sabre. But the lead illustration in the
Wired article is the Reaction Engine's Sabre engine not the Fenris. I
wouldn't be too happy with that if I were from Reaction Engines. I
haven't had time yet to study the Fenris, so I have no clue as to how it
works and in what ways it is different from a Sabre engine.

As Henry Spencer points out (again and again) LOX is cheap and
plentiful. These air breathing designs are optimizing for the wrong part
of the problem. You'd have to get enormous reuse out of these systems to
compete with a single Falcon Heavy launch. And once Starship becomes
fully operational, well, maybe they could launch Skylons out the cargo bay.

I wish these designs good luck from an engineering prospective I think
they are very interesting. Will they ever compete against traditional
two stage rockets? It could be the Stanley Steamer vs. the Gasoline
Engine all over again. I suspect these systems have a much better future
as quick deploy crewed military vehicles rather than cargo lifters.
There just isn't enough oomph there. And don't forget Starship in its
two stage version is also fully reusable w/o the technical complications
of a bleeding edge engine.

BTW if you an basing your fuel around the hyper hard to handle liquid
hydrogen in order to make the Reaction Engine work at all, you are
really really up against the fuel density issue.

Or as Ben Rich called them, Wide-Bodied Dogs....

Dave

On Sat, 27 Jun 2020 15:19:31 -0700 (PDT), wrote:

"The two men arrived at the airfield before dawn to set up the test stand for a
prototype of their air-breathing rocket engine, a new kind of propulsion system
that is a cross between a rocket motor and a jet engine. They call their unholy
creation Fenris, and Davis believes that it’s the only way to make getting to
space cheap enough for the rest of us. While a conventional rocket engine must
carry giant tanks of fuel and oxidizer on its journey to space, an air-breathing
rocket motor pulls most of its oxidizer directly from the atmosphere. This means
that an air-breathing rocket can lift more stuff with less propellant and
drastically lower the cost of space access—at least in theory.

The idea to combine the efficiency of a jet engine with the power of a rocket
motor isn’t new, but historically these systems have only been combined in
stages. Virgin Galactic and Virgin Orbit, for example, use jet aircraft to carry
conventional rockets several miles into the atmosphere before releasing them for
the final leg of the journey to space. In other cases, the order is reversed.
The fastest aircraft ever flown, NASA’s X-43, used a rocket engine to provide an
initial boost before an air-breathing hypersonic jet engine—known as a scramjet—
took over and accelerated the vehicle to 7,300 mph, nearly 10 times the speed of
sound.

But if these staged systems could be rolled up into one engine, the huge
efficiency gains would dramatically lower the cost of getting to space. “The
holy grail is a single-stage-to-orbit vehicle where you just take off from a
runway, fly into space, and come back and reuse the system,” says Christopher
Goyne, director of the University of Virginia’s Aerospace Research Laboratory
and an expert in hypersonic flight."

See:

https://www.wired.com/story/the-rock...-a-jet-engine/


Sounds like another air augmented rocket to me. On NTRS:
https://ntrs.nasa.gov/search.jsp?R=1...atchallpartial

Operationally efficient propulsion system study (OEPSS) data book.
Volume 10; Air Augmented Rocket Afterburning
Document ID: 19980041407
NTRS Full-Text: View Document [PDF Size: 1.3 MB]
Author: Farhangi, Shahram; Trent, Donnie (Editor)
Abstract: A study was directed towards assessing viability and
effectiveness of an air augmented hide
ejector/rocket. Successful thrust augmentation could potentially
reduce a multi-stage vehicle to a single stage-to-orbit vehicle (SSTO)
and, thereby, eliminate the associated ground support facility
infrastructure and ground processing required by the eliminated stage.
The results of this preliminary study indicate that an air augmented
ejector/rocket propulsion system is viable. However, uncertainties
resulting from simplified approach and assumptions must be resolved by
further investigations.
Publication Year: 1992
Document Type: Technical Report
Report/Patent Number: NASA/CR-92-207458, NAS 1.26:207458,
RI/RD90-149-10-VOL-10, CDR-91-099
Date Acquired: May 23, 1998

Hi all,

As a long time observer of the Sci.Space.* groups, and of the space and aerospace industry I'm have become tempted to call Scram jets and other air-breathing solutions (including Sir Richard's noble attempts out in the US Midwest) as SCAM-jets. They're a neat way to keep engineers and scientists funded, but highly unlikely to ever produce an actual useful product. See NASA X-33 program, and possibly Orion and SLS as examples of this.

They all demand incredible technologies and enormous flight rates just to make them look even vaguely economical. AS David Spain pointed out, that Henry Spencer regularly points out, LOX is cheap, and TSTO operations and technology is relatively well understood.

Now the heat exchanger tech that Reaction Engines Sabre is supposed to use is incredible. Someone stated that it had basically shrunk the technology and machinery that used occupy an entire (large) building into a shipping container. But its still nowhere near light enough, or efficient enough to actually supply the Sabre's thirst for oxidizer.

And the sticky question remains: if you've cooled and compressed enough atmospheric oxygen to power your upper and out-of-atmosphere flight phase what did you do with the other 80% of the atmosphere you processed. Note if you are turning atmospheric Oxygen into LOX you can't avoid producing Liquid nitrogen on the way. You make LOX by compressing and cooling. Unfortunately LN always happens before LOX because N2 liquidifies at higher temperature and lower pressure than O2. Back on terra-firma the LN generated from LOX production is shipped off to the dozens (if not hundreds) of different industries that use it for making useful products, or cooling stuff down real fast or real low. On your way to LEO you have to ditch it, and that is just WAY TO MUCH WASTE ENERGY being thrown away.

Of cause if you could find a method to turn the O2 and N2 into one of the nitrous oxides and use that as an oxider instead... That might be interesting, and fun to watch from a minimum safe distance. And the technology, if light enough and efficient enough to go into an aerospace vehicle would be a very welcome addition to all sorts of manufacturing here on earth.

REgards
Frank