Hydrogen peroxide helicopter

"Anthony Garcia" wrote in message . ..
"Lawrence Gales" wrote in message
news:Pine.WNT.4.58.0407172228370.1384@your-kgj38sd53j...
[snip]
You might check out Len Cormier's Space Van 2008:

http://www.tour2space.com/sv2008/sv2008.htm

Len claims a number of advantages in *slowly* getting an orbiter to a
high
altitute (about 70,000 feet) and then releasing it at a moderate speed,
about 350 mph:
- Greatly reduced structural weight due to
o Not having to fight your way at high speed through the lower
atmosphere (remember the shuttle would tear itself to pieces if
it
did not throttle down to 65% around 40,000 feet)

Unless you have a carrier aircraft bringing the launch vehicle up to
altitude you're trading off one sticky problem for another. You still
must use an oxidiser, if you expect the launch vehicle to be airbreathing
until using rocket propulsion you have the issue of added weight unless
you jettison something.

You don't seem to get it.

Oxidizer that is cheap and that you get rid of is not
a "sticky" problem. Nor are the tanks, which stay
with the "kite" stage. In fairness to the context
of your comment, the kite stage is a form of a
carrier aircraft--but much cheaper and with important
differences.

You're right, airbreathing is quite inappropriate
for short duration flights spanning large altitudes.

Nothing is jettisoned--as in "thrown away." The
lightweight propellant tanks stay with the kite
stage and are easily recovered and used again.
Whether or not the rocket engines used for climb
stay with the kite or the orbiter is an option
for the current design. Thrust-to-weight builds
up from about 0.4 at takeoff to about 1.2 at
separation, which is appropriate for ballistic
flight after separation.

o Not having to have strength in as many directions as its
attitude
is always nearly horizontal

Now you have TWO structural problems instead of one. You must still have
the strength to withstand the acceleration when the rocket is thrusting
(2-7+G plus dynamic loading) AND you must have the horizontal strength to
withstand the structural load of being hoisted to altitude (probably 2-5G
plus dynamic loading) and this horizontal lift must be performed while
fueled

Loads are far less. Captive lifting loads are not much
over 1g, and initial acceleration loads are less. With
allowance for dynamic loads and factor of safety,
3 g's ultimate design factor is appropriate. During
captive fllight these loads are carefully distributed,
and the orbiter aerodynamic surfaces carry none of
these loads. More importantly, panel flutter is not
a problem at low dynamic pressures. The orbiter never
sees dynamic pressures higher than those typical of a
light plane. After separation, loads are more like a
VTO launch system taking off in very low density air.

The dimensions of the kite system are such that there
are very few constraints on the size and shape of the
orbiter. This is another important advantage of the
kite approach.

o Less need for streamlining and thus more efficient packaging

How high do you expect to lift this thing slowly. Unless its up to
~200,000ft+, you are still going to have big aerodynamics problems.

At the beginning of acceleration, 21,300 m (70,000 ft)
is very relieving. The orbiter climbs ballistically
from this point, with dynamic pressure dropping off.
Peak dynamic pressure occurs during initial climb,
with a tradeoff of climb efficient speed versus
limitations of the fabric covered truss structure
used in the kite stage. Eventually you have to be
much higher--as you point out. However, we never
see high dynamic pressure anywhere during the flight.
By the time we reach orbital speeds, we are probably
above 120 km (nearly 400,000 ft.).

- Greatly reduced chamber pressues (e.g., 1400 psi vs 3000 psi)
leading
to *much* longer engine life and reduced costs

Why do you select the particular value's you select for chamber pressure?

We would derate the Aerojet/Kuznetsov AJ-26/NK-33
to 80 percent to greatly increase lifetime. These
are specifics for this engine. We have other
candidate propulsion concepts in mind.

- Greatly reduced mass ratio: if we compare SSME (ground launch) with
RL-10s, the MR reduces from 9.5 to between 6.5 and 7 --- a huge
difference

This mass ratio only counts if you forget the carrier and you find that
you will have a greatly reduced total mass to orbit.

Stage mass ratio is what is important for performance.
Gross mass is a poor indicator of costs--which is
what the game should be about. Payload to orbit
and the cost of getting the payload to orbit--as
well as cost per flight--are the important parameters.

- A much smaller minimum size vehicle: 80-100 tons versus 500-1000
tons



I would say that slow airlaunch to a very high altitude has a very large
advantage

Debateable

While you debate, we'll go to orbit--but,
admittedly, only with financial support.

I like this news group. You can almost always
count on a straight man.

Best regards,
Len (Cormier)
PanAero, Inc.
(change x to len)
http://www.tour2space.com

"Henry Spencer" wrote in message
...

The key question of a rocket-powered rotor is not whether it produces more
thrust at the start, but whether it gains you enough in total -- bearing
in mind that launchers want to accelerate very rapidly and that propeller
efficiency drops off badly as speeds rise -- to be worth its mass. Gary
Hudson said that for the classical Roton design, the bottom line on rotor
lift was about neutral for ascent -- no big gain, no big loss -- with the
main benefits being its other roles: drag device during reentry, lift
device for landing, and centrifugal pump for powered flight.

You know, it just dawned on me... I don't think SS1's "shuttlecock" design
is all that far from Rutan's rotor on the grand scale.

Hmm, interesting. (at least to me. :-)


--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

I found the Space Van 2008 proposal interesting. I had some
comments/questions:

What is the TPS? The slides imply they're not trying for a lifting
reentry. But a cheap, reliable throwaway heatshield isn't going to work
for that design, I don't think. Too much area to cover. Are we back to
RCC for the leading edges? We've all seen how well that works.

I think the 1st stage ascent engine(s) should be part of the gondola.
Is there any reason to carry them up to orbit and back? The attachment
between the orbiter and gondola has to take that kind of stress anyway.

A kite that size is going to be very unwieldly for ground handling.
I'm not sure what would be more practical. It might be easier to keep a
parafoil flat and not flopping around in the breeze than a more rigid
glider.

Related to that...

The SV2008 is also more sensitive to wind conditions. This could cause
launch window problems. Ideally, you'd have a giant circle, with the
winch in the center, so that you could launch into the wind in any
direction.

That's the main drawback to a low wing loading. No easy way to escape
this, AFAICS.

James Graves

John Carmack wrote:

How is lifting the launcher and payload slowly
through the lower atmosphere an advantage?

Probably the biggest advantage of lifting a rocket
launcher above dense part of the atmosphere with
a slow aircraft is the ability to use a very small
rocket launcher. A very small, reusable rocket
launcher is cheaper than any other launcher if you
use it frequently. The upper stage of the launcher
does not have to be streamlined, so it maybe shaped
like the conical reentry capsule.

It is not clear which aircraft is the best.
Hydrogen peroxide helicopter is the slowest.
Rocket plane may be the cheapest. Len Cormier's
rocket propelled kite may be difficult to
control during takeoff and landing.

A versatile canadian telerobot named Dextre will
be probably launched in December 2007 to repair
the Hubble Space Telescope. Another Dextre will
be launched later to service the International
Space Station. These telerobots will be idle most
of the time, so they can be used for other tasks,
for example to assemble large satellites from
small components launched by the very small,
reusable rocket launcher.

Andrew Nowicki wrote in message ...
John Carmack wrote:

How is lifting the launcher and payload slowly
through the lower atmosphere an advantage?

One must distinguish between thrust loads on the
structure and aerodynamic loads on the structure.
There is not likely to be much gain with respect
to thrust loads.

The potential gains of getting to high altitude
"gently" stem from the relief from panel flutter
and from aerodynamic loads and load distribution. Even
VTO ELV's are sensitive to "q x alpha." Lifting
reentry followed by horizontal approach and landing
does not have to involve prohibitive mass penalties.
However, if the lifting provisions have to survive
much higher dynamic pressure during climb and acceleration,
then the aero structure can be quite heavy.

An exception was our 1971 "Windjammer" that became
the Boeing RASV. This type of space transport is
designed for horizontal takeoff, horizontal climb
and horizontal initial acceleration. Initial thrust-
to-system-mass might be only about 0.7--thereby saving
propulsion system mass and avoiding some of the aft
c.g. balancing problems in the empty condition. With
relieving load from LOX in the wings, wing mass might
only be about twice what it would be for LOX tanks
alone. This also results in low planform laoding with
resultant lower peak temperatures--which helps to attain
the required mass ratio and further reduces peak reentry
temperatures--etc.

Each design concept must adhere to a well integrated
design approach. There are different solutions, but
each approach must be well thought out with consistent
design philosophy. Superficial parametric studies--as
distinguished from detail design/analysis studies of
specific concepts--usually lead to misleading conclusions.
For example, some studies of HTOL vehicles have been made
by VTOL advocates who merely turned a VTO vehicle on its
side, added wings and made the system takeoff horizontally.
These studies were entirely misleading by not adjusting
T/W to proper values and by not taking advantage of such
aircraft-design concepts as relieving load, etc.

I have made other recent posts on this thread that seem
to have gotten lost.

Best regards,
Len (Cormier)
PanAero, Inc.
(change x to len)
http://www.tour2space.com

(Henry Spencer) wrote:
Does anyone really need big, monolithic satellites and big
rocket launchers? It seems that satellites of any size can be
assembled in orbit by telemanipulators.

That's an interesting theory, to date completely unsupported by actual
demonstrated results. (The robotics guys I know would probably ask what
you've been drinking.) The proven way to do orbital assembly is with
people, not robots, doing the work.

I note that *he* said telemanipulators, *you* said robots. The two
are not quite the same thing.

D.
--
Touch-twice life. Eat. Drink. Laugh.

In article ,
Derek Lyons wrote:
...It seems that satellites of any size can be
assembled in orbit by telemanipulators.
That's an interesting theory, to date completely unsupported by actual
demonstrated results. (The robotics guys I know would probably ask what
you've been drinking.) The proven way to do orbital assembly is with
people, not robots, doing the work.

I note that *he* said telemanipulators, *you* said robots. The two
are not quite the same thing.

The terminology is not reliably precise enough to make such fine
distinctions; the robotic hardware in question is all teleoperated.
(Some of the robotics guys in question worked on the exact hardware
he thinks is so miraculous. It's not.)
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |