Re: Atmospheric Flight to Orbit

It is an acceleration profile, not a range/endurance which most engines have
been optimized for. I've always felt the best variable intake would be a
fluid (or gas) variable intake for an acceleration type mission, even
though it's not very useful for a range/endurance type mission profile.

It helps in a lot of ways with the crawl stage. The inlet's variable
structure can be optimized for only a few Mach numbers (maybe even just
one) instead of having to be continously variable. Precools the air,
enriches the air with Oxygen, extends the useful Mach range, keeps heat
loads down, increases acceleration...it simplifies a lot. Of course, the
extra Oxygen onboard does weigh something, but this can be minimized with
the right Mission profile.

I'm missing something about why you think they fail. Getting to a Mach 6 or
7 with an ISP over 1000 is a pretty good. Are you saying zero (or negative)
performance gain to Mach 6? Could you give me a reference to the trade
study you are referring too?

This is about the velocity at which most rockets stage. For rockets, a large
percentage of their energy is consumed just getting to this point.

--
Craig Fink
Courtesy E-Mail Welcome @ WeBeGood@xxxxxxxxx
--

john hare wrote:


"Craig Fink" <WeBeGood@xxxxxxxxx> wrote in message
news:LRfGh.5877$PL.3762@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Cool, so your engine is an attempt to bridge the ISP gap between jets and
rockets. Sounds like it does.

A child must learn to crawl before it can walk, then walk before it can
run.
Sounds like your engine is in the crawling stage of Atmospheric Flight to
Orbit. Does your engine take you from 0 to 5k-6k fps with an ISP of
1000+?

It is an engine concept with a reasonable chance of working, not hardware.
It would be usefull to about that speed if very active measures were
taken to handle intakes and thermal problems. The variable intakes to
handle that
mach variety mass more than the engine itself. The heat loads on the
vehicle
and engine through that range add considerable mass, complexity and design
problems.

It also sounds like your study was attempting to run all the way to
Orbit. An SSTO? If you turned the engine off, you should have dropped it.
What was
your performance gain when you turned the engine off? Could I have a copy
of your paper? Sounds like interesting reading.

I didn't do a formal paper. To get an idea of the concept, look up
air-turborockets.
Then check out centrifugal compressors and radial inflow turbines. My
concept
recognizes the similarity between a squirrel cage fan and those two
turbomachines
to give a regen cooled engine.

My point is that I have a vested interest in air breathing engines for
this purpose,
and they fail.
--
Craig Fink
Courtesy E-Mail Welcome @ WeBeGood@xxxxxxxxx
--

john hare wrote:


"Craig Fink" <WeBeGood@xxxxxxxxx> wrote in message
news:zRWFh.7664$_73.5431@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I would think that the advantages of airbreathing engines are
tremendous. A
payload increase in the 100% to 1000% range. There is a huge
performance gap (ISP to SPF Specific Fuel Consumption) between rocket
engines and airbreathing engines. From 600 for the best chemical
rockets to the 1000-4000 for airbreathing engines. Doubling the ISP of
the best rocket engine will more than double the payload.

In my opinion, not much has been done or studied to bridge this gap. If
your
trades don't give a serious advantage then something is wrong with your
trades. Like, maybe they had the wrong engine.

The regulars here have excersized diplomacy in not pointing out that
I have a vested interest in finding a use for air breathing engines for
spaceflight. I did a short talk on an air breathing engine I invented
at Space Access 04. On paper it should have a very high T/W ratio
with fair fuel consumption. Better than any jet flying today. I did
the trades. On pure performance, pure rocket wins every time. I
have to find other reasons to justify use of my concept.

The ABE Isp is only good for narrow bands of speed and altitude. The
very high weight of most air breathing engines is dead mass for the
rockets to carry from their cut off velocity to the vehicle final
velocity. That dead mass eats up far more fuel than is saved in the
early climb. My concept engine, a variation on the air-turborocket,
should get 25+ to 1 thrust to weight, with an Isp well over 1,000. The
trades still don't close for it on performance alone.


.

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