Air breathing re-entry concept

(Oren Tirosh) wrote in message . com...
(Zoltan Szakaly) wrote in message
..
I admit that I am somewhat liberal in my pursuit of new ideas, but I
think that's how good brainstorming is done.

1. You guys probably think that ramjets do not work at a stand-still,
under static conditions. I have three in my garage that work at 0
velocity, they suck in air and they pump out heated air. They burn
fuel with the air as oxidizer. They have no moving parts and get an
Isp of over 4,000. I am experimenting with these because I want to
build a practical flying car.

You have working hardware. I applaud that. But they are not ramjets.
If the *suck* in the air rather than have it *rammed* in by ram
pressure they are not ramjets. Call them induction jets.

Here's what I would do for space access with a jet engine that is
cheap, reliable, has no moving parts, high thrust-to-weight and can be
scaled up to large sizes: I would build a reusable launch assist
platform that lifts a conventional rocket to a high altitude launch.

Air launching is currently limited by the carrying capacity of
existing aircraft and their physical configuration. Developing new
heavy lift aircraft is extremely expensive and cannot be justified for
a vehicle that will not be built in significant numbers. If such a
platform could be built from "dumb" components with cheap, heavy
materials and large margins its development should be relatively
cheap. It doesn't have to be anywhere near as efficient as
conventional aircraft - nobody is trying to save cheap fuel when
launching to space. It just needs to have an Isp high enough so that
its weight is not totally dominated by fuel like rockets. This way it
can be scaled up without having its size balloon out of control. I
think your induction jets might be suitable for such a platform.

Oren

I think you are completely correct. These engines are light, cheap,
simple,
so they could be used for a low tech lifting vehicle like an air
breathing first stage. I have also contemplated air breathing flyback
boosters that
would increase payloads of existing launch systems.

I would like to build a flying prototype of my flying car that can
hover
for maybe 20 minutes to half an hour.

Zoltan

Jim Davis wrote in message .1.4...
Zoltan Szakaly wrote:

I have three in my garage that work at 0
velocity, they suck in air and they pump out heated air. They
burn fuel with the air as oxidizer. They have no moving parts
and get an Isp of over 4,000.

How do they manage to suck in air with no moving parts?

Jim Davis

By injection of hot fuel vapors into the inlet under high pressure.

Zoltan

Henry Spencer wrote:
In article ,
Zoltan Szakaly wrote:

What if I have a metal nose cone filled with a liquid and as the
liquid is heated it boils out through a hole at the very tip.
This would work for a conventional cylindrical rocket that comes back
nose first...


Schemes somewhat along those lines have reportedly been used for ICBM
warheads, which want to keep their velocity as much as they can (to make
interception difficult).

They also would want to do this because the heat rate at the surface of
the RV is an inverse function of the radius of curvature, and is very
high at the tip (that's the other reason for blunt reentry bodies, to
keep the shock far away.)

IIRC, liquid lithium has been proposed for this in pointy vehicles to
be launched from ground-based accelerators (coilguns or the like).

Paul

(Zoltan Szakaly) writes:

Jim Davis wrote in message .1.4...
Zoltan Szakaly wrote:

I have three in my garage that work at 0
velocity, they suck in air and they pump out heated air. They
burn fuel with the air as oxidizer. They have no moving parts
and get an Isp of over 4,000.

How do they manage to suck in air with no moving parts?

By injection of hot fuel vapors into the inlet under high pressure.

In standard technical terms, it's what has long been known as an
"ejector jet," with the additional wrinkle of an "expander cycle" added ---
essentially conceptually identical to a simplified form of the Gluhareff
"pressure jet" engine (which uses a multi-stage ejector to gain performance).

Note also that the "light with moving parts" claim is a bit misleading,
since the fuel must be fed to the engine at as =LEAST= as high a pressure
as the vapor is being injected into the inlet at. Therefore, you've either
got to have high-pressure fuel tanks (which are massive and expensive),
or a high-pressure fuel pump (which is massive and will consume power).


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

Zoltan Szakaly wrote:

I think you are completely correct. These engines are light, cheap,
simple,
so they could be used for a low tech lifting vehicle like an air
breathing first stage. I have also contemplated air breathing flyback
boosters that
would increase payloads of existing launch systems.

Like a ... plane? I actually rather like the idea of air-breathing
reusable flyback first stage (whetver monolithic or cluster).
it should also lety youtest systems and stages separately without
major hardware losses.


I would like to build a flying prototype of my flying car that can
hover
for maybe 20 minutes to half an hour.

Zoltan

--
Sander

+++ Out of cheese error +++

In article ,
Michael J Wise wrote:
...essentially an ablative heatshield where you can refurbish the ablator
by refilling a tank, which is very nice. But nobody has a very clear
idea of how best to arrange the details.

Maybe they should try a few tests?

This is another area (in addition to advanced rocket propulsion) where a
program of modest X-vehicles could make a huge difference. Heatshield
technology really is rather poorly developed, except for one or two very
specific approaches which have serious disadvantages. Jeff Greason's
comment at last spring's Space Access was "we're in about 1902 for TPS".
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |