My own TSTO

Since I have been working on my flying car development I started to
contemplate what it would be like if I tried to go to orbit.

For starters I imagine that I already have finished the flying car.
This is a composit four seater vertical takeoff airplane/car that
weighs about a ton fully fuelled with four passengers. It uses air
breathing ramjet-like engines that allow it to hover and to takeoff and
land vertically as well as fly horizontally.

I have considered how hard it would be to build an SSTO and made some
basic computations.
I will include here a logarithm table:
x , ln(x)
2 ,0.69
3 ,1.10
4 ,1.39
5 ,1.61
6 ,1.79
7 ,1.95
8 ,2.08
9 ,2.20
10 ,2.30

Next I will print a table for the necessary mass ratio values both for
orbit (8400 m/s) and half orbital (4200 m/s) velocities as a function
of engine Isp values.
Isp half full
500 2.35 6
450 2.59 7
400 2.92 8.5
350 3.40 11.5
300 4.20 17
250 5.50 31

From the first table I conclude that it makes sense to try to achieve
at least a mass ratio of about 7 in a stage, for two reasons: 1. It is
feasible, not very difficult 2. Higher mass ratios increase risk of
structural failure, lower mass ratios don't get the job done.

So I imagine I build an LOX-LH2 upper stage with an Isp between 400 and
450 and a mass ratio between about 7 and 8. This upper stage can in
itself achieve a dV of 8400 m/s. Now I have a total mass of about 16
tons with the flying car fully fuelled and the upper stage fully
fuelled.

Instead of using the 8400 total dV to go to orbit, I want to use half
of my dV on the way to orbit, the other half to decelerate before
reentering on the way home.

So what I do is build a first stage that launches me to something like
100 miles up with a horizontal half orbital velocity. My first stage
will weigh somewhere around 100 tons or maybe 150 depending on how
low-tech I make my engines. If I am lucky and successfully use an air
breathing engine that functions as a hydrocarbon rocket engine higher
up, I might have a 50 ton fist stage.

The first stage reenters at 4200 m/s which is much more gentle than
full orbital velocity (a quarter of the energy). Subsequently it glides
to a nice landing to be reused. After completing its orbital mission
the second stage uses its extra dV to decelerate from orbit to 4200 m/s
and it also performs a gentle re-entry.

In fact the shuttle itself could be used as the upper stage of such a
scheme. It would just have to be better boosted so that it would not
use all its fuel on the way up.

Based on the 450 Isp the shuttle is almost an SSTO.

"zoltan" wrote in news:1131690394.686827.14560
@g49g2000cwa.googlegroups.com:


For starters I imagine that I already have finished the flying car.
This is a composit four seater vertical takeoff airplane/car that
weighs about a ton fully fuelled with four passengers. It uses air
breathing ramjet-like engines that allow it to hover and to takeoff and
land vertically as well as fly horizontally.

How do you get a ramjet to work at all? What do you mean
by 'ramjet-like?

--Damon

zoltan wrote:

Based on the 450 Isp the shuttle is almost an SSTO.

Almost, but not quite. Your SSME Isp is in a vacuum, not at launch.

http://www.boeing.com/defense-space/...opul/SSME.html
http://www.spaceandtech.com/spacedat...me_specs.shtml

We just need to get rid of the orbiter and SRBs, and build a better ET,
er ... IT.

http://webpages.charter.net/cosmic
http://webpages.charter.net/tsiolkovky
http://webpages.charter.net/tsiolkovsky/rocket.htm

I have been working on the development of these engines that use a
venturi effect to drive the intake air into a ramjet like structure.
The fuel regeneratively cools the combustion chamber and nozzle walls
and it is then injected into the intake where it pumps air into the
engine that subsequently provides the oxiizer for the burning.

I get about 4000 static Isp with high thrust to weight. I am working on
a prototype flying car using these induction jet engines. I have
developed the fly by light control system and I am working on
integrating a prototype.

I am contemplating using the induction jet engines as booster engines
where they would save money by working as rocket engines higher up, out
of the atmosphere. This would be accomplished by oxidizer injection
higher up where there is not enough air.

In this post I was actually contemplating boosting the shuttle to a
4200 m/s velocity before the SSMEs ignite. They would ignite in space.

Uh, right, sure, uh-huh.

Damon Hill wrote:

How do you get a ramjet to work at all?



First, rockets are used to bring the car up to ramjet ignition speed:
http://image.www.rakuten.co.jp/miket...271653560.jpeg :-)

Pat

zoltan wrote:

I have been working on the development of these engines that use a
venturi effect to drive the intake air into a ramjet like structure.
The fuel regeneratively cools the combustion chamber and nozzle walls
and it is then injected into the intake where it pumps air into the
engine that subsequently provides the oxiizer for the burning.


This sounds like one of these: http://www.vortechonline.com/jets/
http://www.vortechonline.com/jets/gallery/

Pat

I guess the points I was trying to make were the following:

1. An SSTO is not hard to build, in fact the shuttle is an SSTO. You
can make a rocket with a delta-V of 8400 m/s using a SSME and a mass
ratio of 7.

2. It makes a lot more sense to build the TSTO that I described,
because BOTH stages return to Earth at a mild 4200 m/s velocity,
simplifying the structures and reducing the risks. Both can be reused
by simply refuelling them.

3. Air breathing engines can be used for first stage boost as well as
hover or vertical landing. They are light and cheap, they can be easily
made and have very high Isp values. You can build the booster of the
TSTO using an air breathing induction jet engine and a mass fraction of
4 using hydrocarbon fuel with LOX. It can even come back perform a
hover and a vertical landing.

zoltan wrote:

I guess the points I was trying to make were the following:

1. An SSTO is not hard to build, in fact the shuttle is an SSTO.



No it is not.

Pat