Re: Skydiver Design insights

Hi Shawn,

Thank you very much for your detailed technical comments!

Shawn Kelly wrote:
> ALSO, as for the Sky launching rocket motors, you get a far better
thrust to weight ratio for solid rocket motors rather than liquid
propelled ones.
> I firmly vote for solid fuel boosters.
> Solids are also very much more reliable than liquid fueled motors,
they can be waterproofed easily and would be easy to auto-reload by
diver with cartridges, (just like overgrown Estes model rocket engine
cartridges).
> Liquid fuel rockets often require overhaul between firings, all
large ones that I know of do, only the small ones seem to tolerate
multiple firings.
> Multiple firings of a liquid fuel booster would also be complicated
by being submerged between flights.
> I see nothing in Sky1's launch characteristics (as shown to us)
that indicate other than SRBs and SRBs just make a lot more sense.
> A pilot could easily nose down and fly level without throttling up
the main engine if he wished to stop climbing after launch,
throttling up the main engine only after the SRBs burn out.
> If he wished to go straight to max ceiling then he would throttle
up the mains as soon as he left the water and maintain his climb
using both until the SRBs burnt out.

Hurrah, I've got an encouraging supporter on the solid fuel booster
theory!
On the other hand, I have stumbled on an idea...
I suppose that the SHADO's fighter aircraft named Sky was developed
step by step.
In the first place, there should have been some prototypes, which
were used for test flights and accumutated many data.
Then, the first production type, Sky 1, was manufactured and sent
into battle in 1980.
Nest, the second one, the Sky 2 which was slightly improved would
follow.
Therefore, we may be able to think that one of the variants of Skys
has solid rocket boosters and another one has liquid fuel rocket
engines.

For reference, please remember the Interceptors.
In the early episode 'Computer Affair', the Interceptor could not fly
in space independently without the instructions from the Moonbase
control, and it had a collision with a Ufo.
But in the later episodes, Interceptors fly just like fighter
aircraft and purchase Ufos.
Probably, the advanced version of the Interceptors were equipped with
the autonomous navigation system something like INS and GPS.

> LASTLY, Those doors on the bottom of Sky1...

Which one, sir? (The one in the best position?)

> I would venture that they are actually exit doors for water.
> First off, a large portion of sky will have to be filled with water
and pressurized to prevent sky from simply being crushed by the
water.
> Not so much by the static pressure of just being submerged but more
by the hydrodynamic forces of plowing through the water at 40 knots.

Yes, indeed, it is quite difficult to let Sky 1, which is basically a
light and fragile aircraft, withstand the water pressure.
In the episode 'Destruction', the Skydiver went underwater, the depth
900 feet?
When the Skydiver submerges, the Sky is unmanned except its launch
sequence.
Therefore it is a very good idea to pressurize the inside of the Sky,
and probably it is the only practical way to prevent being crushed by
the water pressure.
I, however, am afraid that it is not very good to fill the inside of
the Sky with water, especially the cockpit!
So how about filling it with pressurized air just like ballast tanks?


Kaoru

It's too bad I can't find it, but when I was in school, I wrote a story
based on UFO. In it I described my vision for various pieces of UFO
hardware, based on my childhood impressions of the show (I hadn't seen it
since 1973 mind you) and everything I'd learned about aviation since then.

see below


>Date: Wed, 11 Jun 2003 00:03:06 -0000
>From: "tchbnk" <[hidden email]>
>Subject: Re: Skydiver Design insights
>
>Hi Shawn,
<SNIP>
>For reference, please remember the Interceptors.
>In the early episode 'Computer Affair', the Interceptor could not fly
>in space independently without the instructions from the Moonbase
>control, and it had a collision with a Ufo.
>But in the later episodes, Interceptors fly just like fighter
>aircraft and purchase Ufos.
>Probably, the advanced version of the Interceptors were equipped with
>the autonomous navigation system something like INS and GPS.

The majority of what would have been done for the interceptor situation I
would suspect would be procedural and also circumstantial. The latitude
given the pilot in the later episode that the earlier one did not have
could simply been a matter of circumstance. flying out in space away from
things there would be a lot more latitude for the pilots to perform evasive
maneuvers as required whereas closer to the moon, satellites or other
facilities there would be a greater dominance of ground control. Hardware
wise, to give the interceptors more flexibility for course changes it would
only be required to add a data link to let the ground computers communicate
directly with the interceptor nav computer, a small box and an antenna.
However what would be required to convert a liquid fueled booster Sky to a
solid booster version would be a tremendous redesign of the hardware. Fuel
tanks. piping, connections with diver, fuel tanks on diver... all of the
logistics for liquid rockets. Compared to the logistics of the solids
which might involve an autoloader on diver and handling of a pair of big
heavy cylinders. The differences between liquid and solid handling
logistics and hardware are so great that it would have to look and act
different. I'm sticking to my conviction that Sky is and always has been
launched with solid boosters.

One thing that is also remotely possible should I be proven completely
wrong about the SRBs is the possibility of oxidized liquid-fuel rocket
engine boosters that use the same jet fuel as the main air breathing
engine. Many current liquid fuel rocket motors are using light hydrocarbon
fuels (from heavy diesel to naphtha), jet fuel falls into this category and
could easily fuel an oxidized rocket engine designed for it. It would mean
that Sky would have to carry an oxidizer aboard though and it is hard to
handle and very dangerous not to mention very heavy. Very low temperatures
and very high pressures.

Something else that was mentioned was a 250,000 ft ceiling for Sky. That's
47 miles and just on the verge of space... air breathing engines cannot
operate there, there is far to little air up there. Sky would have to have
an oxidizer aboard in order to do anything more than a ballistic arc that
high (unpowered above 150,000 ft). So either the 250K number is wrong or
there is an oxidized engine aboard.

Perhaps the bulk of sky's body is to contain the oxidizer. For a hybrid
"oxidized-when-needed, normally air-breathing" engine. Such engines are
experimental only (officially) right now in 2003 but are not new in
concept.

A possibility:
Such a system in Sky would have to be integrated, there would be 4 main
modes of operation and two expendable propellants aboard, jet fuel (JP) and
oxidizer (Ox). There just wouldn't be enough room for independent systems
and weight would always be a problem no matter what, integration reduces
weight by sharing resources and hardware. the 4 main flight modes would
be:
1) Booster rockets in and up out of the water with JP & Ox
2) Normal flight with JP & air
3) very high altitude flight with JP, air and some Ox
4) edge of space flight with JP & Ox

Modes 3 and 4 would also require thrusters for attitude control as there
isn't enough air for flight control surfaces either.

Interestingly: Sustained flight at 250K is essentially a very low
unsustainable orbit and all but impossible. There is enough drag to slow
you down, enough to heat you up, no lift for wings, the only way to stay
there it to be at orbital velocity (impossible) or have thrust UNDER you
rather than behind. If you fly there at orbital velocity then you are
going to be doing a Columbia impersonation in no time flat. There really
never has been sustained flight there because you would have to essentially
cross an X-15 with Harrier to do it. You would have to be traveling far,
far below orbital velocity to keep from burning up but at the same time you
would require a thrust against gravity to keep you there because your wings
cannot do it. The only flight there is just to pass through; either
into/out-of space or in a ballistic/semi-ballistic flight up and
immediately back (3-6 minutes at the needed speeds). Its flying in the
part of the flight envelope where the stamp gets cancelled, yes maybe you
can go there briefly but you don't hang around long. :-)

<SNIP>
>I, however, am afraid that it is not very good to fill the inside of
>the Sky with water, especially the cockpit!
>So how about filling it with pressurized air just like ballast tanks?
<SNIP>

I wouldn't have flooded the cockpit, turbine engine or electronics bays
anyway but I agree, in going over it I don't think there are very many
areas flooded with water, pressurized air or nitrogen is more likely.
Undoubtedly it would be filled and pressurized with several different
things when submerged but it survives a high speed ascent through the water
with normal air in the cockpit so the windscreen and entire cockpit simply
have to be very strong.

Fill what with what:
1) Jet fuel; it would be best to vent all air from these tanks and have
them filled completely and pressurized with fuel at pressure kept equal or
above water pressure
2) Oxidizer tanks, are a problem, they would probably have to be drained
and refilled only just before launch because of the way LOx has to be
handled. The tanks in Sky would have to be nitrogen purged and warmed up
after evacuating the LOx to prevent ice buildup (if you warm it with the
LOX present then the LOx goes away out relief valves [or explodes]). Diver
would need refrigerated insulated tanks and some way to deal with the ice
buildup on LOx systems.
3) Air or nitrogen pressurization of un-hardened areas like electronics
compartments, (not cockpit or pilot loading tube).
4) Air or nitrogen at higher than water pressure for large forward facing
surfaces like the intake nacelle and missile pod shells, these can remain
pressurized at all times for strength, even in flight
5) Filtered water fill (open to water pressure) other compartments like
internal cavities around the tanks, inside fins and control surfaces, helps
reduce buoyancy.

Here's a suggested launch sequence once the order is given, (it works for
either type of booster design):
1) Transfer LOx to Sky
2) Purge water filled cavities with air or nitrogen (will increase
buoyancy, perhaps responsible for pointing SkyDiver up for launch)
3) pilot in place
4) Nitrogen or air purge booster rocket nozzles just before ignition
5) Ignite boosters & launch, belly doors allow scooped water to bypass main
engine
6) on breaking surface some water filled cavities will still be draining
briefly but the big doors on the bottom will be draining the main air
intake of hundreds of gallons of water, when drained in 2-3 seconds, the
vent doors will close and the diverter will open allowing air into the main
engine. As air passes into the engine, expendable covers are blown off the
exhaust slits (like US stealth planes slits)
7) main engine will spin-up from mostly ram air through the intake,
electrically assisted if needed and be started.
8) Main engine will be throttled up as required to assist or not, the
boosters still firing.
9) boosters out, main engine up, normal flight.


Sky can do a computer flown tail stand and set gently into the water to
land. Computer flown because the pilot can see only sky anyway. Then all
it has to do is sink and let Diver grapple it somehow (several ideas here
too). The engine would be re-sealed and air/nitrogen purged after docking.

Maybe I've told you guys too much... now I'm going to have to have you all
over for some of that special blend SHADO coffee. :-)

S
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