Re: How Rockets Differ From Jets

Brad Guth wrote:
> "They say" a lot of things. "They say" the mutual
> gravity-well/nullification zone between us and the moon is roughly 84%
> of the distance towards the moon, and thereby we're talking 16% of the
> distance away from the moon.


I regard many of 'their' calculations/equations as . . . suspect. When
you start taking averages the other horse wins every time.

All of a sudden 'they' decide that Moon gravity takes effect. The fact
is the Moon's gravity travels all the way to the Earth, hence the
tides.

The pilot of a spaceplane should 'aim' at the Moon or, actually, lead
it a little to get full benefit of the Moon's gravity which, by the
way, changes all the 'equations'. You don't actually have to follow a
preprogrammed course!

'Their' mathematically 'perfect' equations leave me a little worried
about whether or not they actually . . . work. Properly 'set up'
mathematics should do a fine job, but the laziness of taking averages
like 32'/per second squared divided by 2 -- and not taking into account
the Moon's gravity -- is a little upsetting.


> With regards to spaceplane wings or perhaps that of one massive
> aerodynamic foil worth of a waverider spaceplane body, thus affording
> far more usable interior than any tile covered wing outfitted body as
> suggested by your "huge gleaming white triangular spaceplane";
> >Rocket equations take drag into consideration, but not gravity's
> >assistance.


Tomcat's 'huge gleaming white triangular spaceplane' does not have
wings. It is a blended wing body that is thicker than a B-2 blended
wing body. It has to be to carry lots and lots of LH2.


> I see no problem with your bigger is better. Of course folks like
> "George Evans" seem to think small by way of continually thinking
> inside the box, as well as having those pesky ulterior motives of
> saying one thing while acting upon getting something entirely different
> across.


George does think in 'detail', however, and that is an ameliorating
factor. Us 'spaghetti' types notice things like that.


> Just wondering a bit; Are you thinking of a 45 degree final atmospheric
> assent?

Interesting question. Once above the atmosphere -- 300,000 feet
approx. -- it makes little sense to stay at 30 deg. climb. Because the
Earth is a sphere, however, it also makes little difference if you
change your climb unless there is some specific place you are going.

It is possible, therefore, to alter to a full 90 deg., straight up,
attitude. A lot depends on whether you are going for orbital insertion
or escape velocity to the planets.

In most cases a planetary mission will require a Moon slingshot and
therefore the Moon's position and your initial takeoff climb have to be
coordinated for best gravity.

What is that best gravity climb? Wait for the Moon to just be poking
it's face above the horizon. Then takeoff like a 'bat out of hell' and
lead the Moon a little, like a hunter leads a buck with his rifle.


> The composites of what basalt fibers and basalt microballoons as having
> a degree of CNT involved seems likely of what should eventually become
> doable. However, of what I've already provided upon existing basalt is
> just the iceberg tip of what that composite alone can achieve as a
> structurally insulative material that need not exceed 64 kg/m3 unless
> the added mass of using more fibers and less balloons becomes a
> priority.


Two things really impress me about basalt fabric: it's insulative
properties and it's psi.


> Too bad that what I have to suggest is much like what you have to offer
> as a plate full of the first, second and third helping, all of which
> should more than have the inert mass of what any SRB assisted
> spaceplane and of it's massive ET should amount to. Thus a replacement
> shuttle as in the form of your "bigger is better" spaceplane should
> have any problem whatsoever achieving those 100t deployments at 400+km,
> with energy to spare.


I believe that new materials and slush tanks enable us to go beyond
just a 'replacement shuttle'. True SSTO is really possible now and,
with some work, a SSTP.


> Of course, if my Ra226-->LRn222-->ION thruster arrays become the
> alternative to those SSMEs that are worth a 10t investment plus fuel
> and the vast volumes necessary for accommodating such fuel per each
> fully integrated SSME and, no matters what these SSMEs should still
> suck LH2 and LO2 like there's no tomorrow, whereas without SSMEs but
> instead LRn-->ION thrusters might represent payloads that can become
> half again or roughly 50/50 of the spaceplane package. Meaning a 150t
> spaceplane that's still having to be SRB assisted (possibly two-stage
> SRBs) past 250,000'(76 km) could thus manage to safely deploy a 150t
> item or that of multiple items that amount to 150t past the 400 km
> mark.


What -- exactly -- is the thrust, in pounds, of your Radon ion engines?
And, how big does the reactor have to be that drives them. If it is
the size of a nuclear power plane, requiring containment domes, then it
might be a little . . . impractical.


> Unfortunately the ulterior motivated likes of "George Evans" being
> rather mindset upon carbon fibers that are extremely frail and spendy
> as all get out compared to basalt fibers, whereas as far as I know of
> there are no such things as carbon microballoons, nor for that matter a
> CNT microballoon. There are however terrific insulative and combined
> structural capability per cm3 of basalt, along with those existing
> graphite epoxy as binders is still the overall king of the hill that's
> not one cent on the dollar per carbon fibers and, perhaps not .001 cent
> on the CNT dollar that's still another good decade down the winding R&D
> road.

CNT might not be a "good decade down the road." DARPA funded the
University of Texas and at least one other CNT project, the Argonne
National Laboratory, I believe. Argonne developed CNT with embedded
diamonds. DARPA's got bucks and DARPA gets what it wants.


> I'd actually think that a little extra thermal conductivity for what's
> directly below the Corelle/ceramic tiles or whatever spray-on ceramic
> microballoon coating would be highly desirable, as possibly performing
> a similar thermal rate of expansion by which this CNT/basalt outer
> shell could best match the rate of ceramic expansion. I do agree with
> "George Evans" that tile fillers need not be incorporated unless no
> other thermal expansion alternative becomes available.



> BTW; I'm not exactly sure how LH2 and slush LH2 differ in energy
> density by all that much.

I don't think the energy density is affect at all. A 'slush tank' just
hold a lot more LH2 than a regular tank.

You might be thinking of the new 'atomic hydrogen' fuel. That is
different, however, than a simple slush tank. The 'atomic hydrogen'
fuel probably needs some additional R&D.


In either case, a terribly insulative
> containment of the likes of LH2 (slush or not) and the same goes for
> LO2 could each be accommodated by way of using a composite of basalt
> fibers and those highly insulative balloons along with the graphite
> epoxy binders if not in some cases just utilizing good old end-user
> friendly JB-WELD.

JB-WELD can only take 500 deg. F. It should not be considered for a
spaceplane, though it might be terrific for many other things where
temperature is not a factor.

A metallic internal coating via plasma spray could
> make for quite another weight saving improvement. In fact, there could
> be two or three viable containment layers of plasma applied metallic
> coatings at less weight impact than a conventional tank that's
> composite wrapped.

Remember, that the meltpoint of metal is dismally low. The exception
if tungsten and if it gets hit with an electrical short or a bolt of
lightning you will get . . . fried by X-rays.


tomcat

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