Posted by Shawn Kelly on
URL: https://www.shado-forum.com/Re-Skydiver-Design-insights-tp1500977p1500998.html



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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