"o.bb.spammed" <o.b### [at] gmailcom> wrote:
> And another

More oops...

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"o.bb.spammed" <o.b### [at] gmailcom> wrote in message 
news:web.4582cda3ff75702cbc81efaa0@news.povray.org...
> "o.bb.spammed" <o.b### [at] gmailcom> wrote:
>> And another
>
> More oops...


Oh, yeah, this is good!

Jon

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Very nice. With Jupiter or Saturn in the background, this would be really 
cool.

Jon

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Jon S. Berndt nous apporta ses lumieres en ce 15-12-2006 06:48:
> "Alain" <ele### [at] netscapenet> wrote in message 
> news:45828032@news.povray.org...
>> Jon S. Berndt nous apporta ses lumieres en ce 14-12-2006 22:07:
>>> "Tim Attwood" <tim### [at] comcastnet> wrote
>>> Hey, I kind of like this (I think I've seen something like this in my 
>>> kitchen, too!)
>>> A couple of notes:
>>> 1) There should be no over-expansion of the nozzle, I think. All of the 
>>> flow would be almost all directed aft.

>> The over-expansion is unavoidable. All you can do, is try to minimise it.

>>> 2) I'm sure this is a WIP, but thought I'd mention that there would be 
>>> more to the engine (a lot of equipment creating magnetic fields - coils 
>>> and stuff, supply lines for fuel, etc.)

>> Depending on the scale, that can be all contained within the nozle.

> Visually, what I would like to see is probably best illustrated by looking 
> at a Hall thruster:

> http://fluid.ippt.gov.pl/sbarral/hall.html

> (see Pratt and Whitney thruster at bottom of this page)
> http://www.engin.umich.edu/dept/aero/spacelab/thrusters/thrusters.html

> http://www.adastrarocket.com/Plasma.html

> There is little, if any, overexpansion of exhaust in these images. The image 
> by Tek was very good in this respect.

> Jon


Plasma or ion engines, indeed, don't show overexpansion. The reason is that the 
plasma have very neglegible pressure. It don't have presure as it's not 
accelerated by the presure but by magnetic and electric fields. I was thinking 
more about chemical or nuclear powered rocket engines. In those cases, the 
exaust have a prety high residual presure as it leave the engine, and that 
residual presure is what causes the overexpansion.

-- 
Alain
-------------------------------------------------
When the bosses talk about improving productivity, they are never talking about 
themselves.

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"Alain" <ele### [at] netscapenet> wrote in message news:45833d66

> Plasma or ion engines, indeed, don't show overexpansion. The reason is 
> that the plasma have very neglegible pressure. It don't have presure as 
> it's not accelerated by the presure but by magnetic and electric fields. I 
> was thinking more about chemical or nuclear powered rocket engines.

Egg-zactly.  :^)

> In those cases, the exaust have a prety high residual presure as it leave 
> the engine, and that residual presure is what causes the overexpansion.
>
> Alain

Ideally, rocket nozzles are designed so that the flow is optimally expanded 
over the altitude range (pressure range) it operates in. You can't "have it 
all".

Jon
--
Jon S. Berndt
Aerospace Engineer
Houston, TX
-- 
Editor, Horizons, AIAA Houston
http://www.aiaa-houston.org/horizons
-- 
Project Development Coordinator, JSBSim
http://www.jsbsim.org

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Jon S. Berndt wrote:
> Greetings:
>
> I'm looking for a cover image for the fall/winter issue of Horizons, the 
> online magazine for the Houston section of AIAA (American Institute of 
> Aeronautics and Astronautics). See www.aiaa-houston.org/horizons. I'm the 
> volunteer editor for that publication. This issue features one or two 
> articles on futuristic propulsion concepts. I'm looking for an image of a 
> special, realistic, futuristic interstellar or intra-solar system 
> spacecraft, that illustrates powerful propulsion as part of its design. As a 
> long time user of POV-Ray, I figured this would be a good place to ask 
> around. If you have such an image and would be willing to let us use it in 
> exchange only for image credit and acknowledgement, I'd like to hear from 
> you.
>
> "Horizons" has won first place nationally two years in a row, recognized for 
> excellence in production and content. Circulation (downloads) average about 
> 5000 per issue (sometimes as high as 20,000 per issue). It is read with 
> interest in and around Johnson Space Center near Houston, Texas.
>
> Also, if you are aware of any galleries of renderings (or paintings) of 
> futuristic spacecraft, I'd appreciate hearing about those, too.
>
> Thanks!
>
> Jon
> Editor, Horizons
> AIAA Houston
> www.aiaa-houston.org/horizons
>
>
>   
I am surprised that no one posted this link
http://www.bisbos.com/rocketscience/spacecraft/daedalus/image_general1.html

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> Ideally, rocket nozzles are designed so that the flow is optimally 
> expanded over the altitude range (pressure range) it operates in. You 
> can't "have it all".
>
> Jon
> --
> Jon S. Berndt
> Aerospace Engineer
> Houston, TX

If I remember correctly the engine bells of the 1st, 2nd and 3rd stages of 
the Saturn V were quite different shapes to accomodate this.

This is one of the advantages of the aerospike type of engine... It 
effectively uses the atmosphere as the outer wall of the expansion chamber, 
thus it automatically adjusts to external atmospheric pressure.   What a 
great pity the X33 and Venturestar programs were shelved!

Assuming the spacecraft didn't need to enter atmosphere, i.e. it was an 
interplanetary craft, its engines would only need to operate in a vacuum, so 
no adjustment would be required.

Rarius

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"Art Flint" <afl### [at] stxrrcom> wrote in message

> I am surprised that no one posted this link
> http://www.bisbos.com/rocketscience/spacecraft/daedalus/image_general1.html

An excellent link. Thanks!

Jon

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"Jon S. Berndt" <jsb### [at] hal-pcorg> wrote:

> "Art Flint" <afl### [at] stxrrcom> wrote in message
>
>> I am surprised that no one posted this link
>> http://www.bisbos.com/rocketscience/spacecraft/daedalus/image_general1.html
>
> An excellent link. Thanks!
>
> Jon

I contacted Adrian Mann (who produced the images at the link, above), and he 
is willing to let me use some of those. Thanks. I'll check back here in case 
anyone finishes up another craft.

Jon

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"Jon S. Berndt" <jsb### [at] hal-pcorg> wrote:
> "EagleSun" <nomail@nomail> wrote in message news:457f2619
>
> > Hi Jon!
> >
> > It's really exciting to see someone from Houston on this forum AND
> > publishing magazines.  Looks like Tek has a very good ship for you....
> > would you need background to go with it?  I've been rendering planets,
> > including a few to show in a movie...
> >
> > Let me know if you need something...
>
> If a ship does come out of this, a planet might be a nice background. Not
> sure if the image would portray braking into orbit or leaving ... hmmm.
>
> Jon

Would a foreign planet portray the fact that it left earth and arrived
somewhere far?

Thanks for writing again... I've also been away mainly because I gave up my
old computer and received a new one, and I'm just getting myself setup on
it.

It's quite difficult to search what you are looking for, hoping it already
exists.  Typically when I search for something, I give myself about 3
months to search, where either I find it after 2 months, or conclude it
doesn't exist.  To get what you want, your best chance is to describe it
and let the volunteers make it.  And I think we would be happy to make
something for a high-profile magazine.

OK, describing my collection...

[America        ][Africa/Asia   ][Planet Houston][Himalayas     ]
[Europe/Asia                    ][Borentuu Sys. ][Uranus        ]
[Saturn Portrait by Cassini     ][Space City    ][              ]

I'm from Houston too, so I like to make planet Houston.

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