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NUCLEARSPACE MESSAGE BOARD (ACTIVE) -> NS ONLINE MEDIA -> Orion Gallery
Post Info TOPIC: Orion Gallery
10kBq jaro

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RE: Orion Gallery
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All I can say is....  my jaw dropped and hairs stood on end. 


Awesome ! 


Congratulations on a superb job !!!!


 



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GoogleNaut

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Rhys,

I definately concur with Jaro: absolutely subperb! Nicely done.

I've played around with PovRay and I managed to render gold pbars and stack them in a pile. Nothing likey what you've accomplished.

Splendid!

Nice job with showing the pulse unit plasma impacting the pusher plate. I would expect some complicated dynamics there--but it might be impossible to see them through the glare anyways. Nice SRB staging seperation. Very realistic after skirt jettison. Nice soft landing on Mars.

I think we should build it!

Ty Moore
"GoogleNaut"


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Terry

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I'm a 'slacker' - but I finally got around to linking the animation from the main NS page.

It is too awesome!

P.S. Rhys, the word is out - there has already been in excess of 7,000 page views BEFORE it was linked from the main NS page. I hope our server can survive!


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Rhysy

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Thanks very much all !


GoogleNaut : According to Dyson's book all you'd see of the pulse unit in space would be bright flash as the plasma hits the plate. Couldn't very well just show that though.


Wasn't sure if the SRB separation was too slow, but by that stage it was too late to re-render. The shroud separation was very easy with Blender's new softbody feature, didn't have to animate that at all !


(Get me 4000 tonnes of steel and a good book on Welding For Beginners and I'll start right away ! )


 


Terry : Guess that's proof people are interested in nuclear spaceships - I can account for maybe 1000 views from other forums !



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Terry

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Well since I linked it from the main NS page the view number has doubled to just under 15,000!

At this rate we may have to charge for admission to the movie! Just kiddin'

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Ashley

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nice!

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GoogleNaut

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Rhysys: I'd say your SRB seperation was just fine. Naturally you can't just 'blow' them all off at the same time--they would get in each other's way and it's very bad to have 185,000 lb of steel casings bumping into another at Mach 4, so you're staggered seperation makes perfect sense.

Ditto for the pulse units. According to Geoge Dysons book, the brightest emmision would occur when the plasma impacts the pusher plate. The Stagnation Shock of the plasma suddenly stopping a millimeter or so away from the pusher plate would reheat the plasma to several hundred thousand degrees. The presumably high-z material (Tungsten was discussed in the book) ought to shine very brightly like the flash from an arc welder, perhaps.

But in all honesty, know one knows for sure until an Orion is built, loaded with pulse units, and then launched into the gulf of space!

Still, Bravo to you!

Terry: 15,000 hits! I wouldn't be too surprised if this animation eventually ends up on a sound bite on CNN!


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Rhysy

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Terry : Cool ! :D


Thanks, Ashley !


GoogleNaut : Guess that's okay then. I meant I wasn't sure if the SRB's were falling downwards too slowly, looked a bit unnatural to me.


I wonder how hot the pusher plate actually gets. If only someone would put all the ample computing power now available into a proper simulation, and answer the ablation question once and for all !



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GoogleNaut

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Cooling the Pusher Plate
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Technically, the SRB's won't fall away if the Orion main vehicle isn't accelerating relative to them. They fall away with the Shuttle, only because the Shuttle main engines keep the vehicle accelerating. Now that you mention it, Rhysy, you'll need seperation motors to give open up the distance between the Orion and the SRB's before the first pulse unit fires. Otherwise you'll scrag your fleet of SRBs'. Perhaps this won't be problem if they are expendible graphite expoxy motors (GEM's,) but I'd be more concerned with x-ray backscatter from them. Keeping jettisoned SRB's the well aft of the pusher plate will prevent this--because the SRB's will always be within the shadow of the pusher plate.

As far as ablation is concerned--this is dealt with by spraying organic grease or oil on to the surface of the pusher plate. The organics are vaporized and ionized which creates a 'radiation transport barrier' just above the surface of the pusher plate. The carbon plasma that is created is fairly opaque to ultraviolet and visible light and is much, much cooler than the impacting plasma is. My guess is that only a tiny fraction of the energy of the impacting plasma from the pulse unit is actually tranformed into heat in the plate. By surface hardening the steal plate with a thick plasma-spray deposition layer of tungsten or tungsten carbide (like a tool bit) this should give it additional heat resistance. From there, just the thickness of the plate will act as a heat sink. Perhaps some active cooling will be needed as well--I'm sure that this was one of those things the original Orion Engineers felt confident about addressing once some large scale flight tests were made.

My gut feeling is that the plate will get hot, perhaps hot enough to eventually mechanically fail. By machining cooling channels within the pusher plate and then filling them with bismuth an efficient heat transfer system could be made. However the real bummer will be trying to figure out how to remove the heat from the bismuth without shaking to pieces a radiatior or heat exchanger. Even flexible metal-bellows style couplings, heavy with bismuth, will be prone to failure because of the violent oscillations of the pusher plate. It is possible that an integral radiator structure could be cast into the back side of the pusher plate and then filling the cooling channels with sodium. Sodium vapor will convect (or more probably be splashed) up the inside of the radiator 'fins' and deposit heat there. Condensing back to a liquid, droplets would be shaken loose and drop back down to the back of the pusher plate on detonation of the next pulse unit. I guess this could be called 'splash cooling' which is analagous to 'splash lubrication' of small lawn mower engines. Depending upon the level of heating of the plate, I suspect a heavy integral radiator with large fins cast in the back side of the plate ought to work. Liquid sodium could transfer a lot of heat this way, and would work well even to temperatures of nearly 1800 degrees F. The size of the cooling fins needed will then be a function of desired operating temperature, the amount of heat to be removed (power radiated,) the total surface area available for radiant cooling, and the number and configuration of fins. By guessing what the input power could be (it's dangerous to guess, and I have no real way to estimate it!) and then juggling the other parameters, an estimate of the size and configuration of cooling fins could be made. Interesting problem--and I'm not entirely sure if the original Orion Engineers went this far!

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10kBq jaro

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RE: Orion Gallery
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Actually, if you look carefully of Shuttle launch videos, you will see that even after the jetison of the SRBs, they still emit a residual orange-colored jet from their main nozzle.


No real thrust, just an afterglow of the preceding fireworks....


Incidentally, if the SRBs are to be recoverable - as those of the Shuttle - then an ocean splash-down is required, not a hard landing in the desert.


PS. apparently the non-SRB Orion version uses conventional high explosives for the initial "bump" off the launch platform, before detonation of the first nuke pulse unit. Wonder how high that first jump might possibly be ?


 



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GoogleNaut

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For a cylindrical charge detonating approximately linearly (along the launch axis of Orion) the impulse delivered to Orion would, I would think, be about 1/2 of the total momentum of the gasses generated by the detonation. Having said this, I would think that the 'lift' derived from such a blast ought to be approximated by the equation: m*g*h=1/2*Vc*rho*Ed where m=mass of the Orion,
g=acceleration due to gravity,
h=lift height of charge,
Vc=volume of explosive charge,
rho=density of high explosives used,
Ed=enthalpy of detonation (usually in KJ/kg.)


While the accuracy of such a simple model could be easily debated, it might give an idea (order of magnitude) needed to begin a truer search for impulse coupling between charge and pusher plate. For high explosives, the relation of 1/2 total momentum coupling to the pusher plate is close to reality only if the charge is pretty close to the plate. However with increasing standoff, the cone angle of of blast must be examined, and then the total impulse will then have to be integrated over the entire surface of the pusher plate as a pressure pulse. This assumes a high degree of knowledge about the distribution of momentum at many points in space distant from the mass of explosives. Such knowledge would almost certainly have to be determined first with computer modeling of the explosive behaviour and/or experiments with live charges on a model.
I'll do a little more digging and see what numbers I can find....

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Rolando

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RE: Orion Animation
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WOW Rhysy....

Your animation turned out beyond imagining. We could almost feel we were right there (and wishing we were).....how many manufacturing hours did it take to put the entire clip together?

My model is pending-too much media and print to ignore for my abandoned mine robotics program in Arizona. But by no means forgotten "Mission to Enceladus". It is on the burner as well as a few planetary images.

Bravo!

TERRY: Have you ever found the Dyson original Air Force "Project Orion" film that was shown to ARPA to sell the program. A frame of this is in the Orion Book by Dyson.

Rolando

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Rhysy

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RE: Orion Gallery
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GoogleNaut : Good point on the SRB's not falling away. It just "looked" unnatural to me. Fooled by common sense again ! :) On ablation : very interesting stuff, though mostly beyond me.


10kBq jaro : Someone mentioned the SRB's don't stop firing until afterwards alread. Unfortunately because of the way it's done I couldn't show this happening - software limitation.


Perhaps it would be easier to suspend the ship in some fashion, over a deep silo perhaps, and just use nukes straight away. Or perhaps use chemical boosting just for the inital height to get well away from any shrapnel thrown out by the explosion.


Rolando, thank you very much ! Hope to see your own short - the more the merrier !



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Ashley

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Rhysy: Perhaps it would be easier to suspend the ship in some fashion, over a deep silo perhaps, and just use nukes straight away.


That was one of the origional ideas.  Or at least a variant of it was.  The Orioneers suggested building towers around the Orion and using them to hold it off the ground, as well as digging a silo under it.  If the towers were shaped right, and built like the pusher plate, they could even survive for re-use.


Wish I could do stuff like this.  Even my parents and siblings found your movie impressive, and they were already sick and tired of me talking about Orion and space travel. 



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Terry

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Currently at 32,245 hits and counting!

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Rhysy

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Ashely : I had a feeling the original study mentioned a large support tower of sorts. Would it - or the pusher plate for that matter - become radioactive with enough use ?


The 3D graphics thing isn't too difficult to learn and makes a great hobby. Give it a go ! Try www.blender.org Making images is just soo much better than ranting on at people ! (doesn't help stop the ranting though - quite the opposite ! That's why I'll be leaving the revamping of the nuke ground launch image for a while, lest I develop an obsession, or more so)


Terry : Excellent ! (the original WIP threads got a total of 11,000 views - in 6 months !!)



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10kBq jaro

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Rhysy wrote:

.....a large support tower of sorts. Would it - or the pusher plate for that matter - become radioactive with enough use ?

Sorry, but here goes another rant


You bet it would become radioactive -- due to both contamination and neutron activation.


However, if the "support tower" is built adjacent to a small cliff, with tracks leading from the plateau onto the tower platform, then the Orion can be rolled onto it, crew & all, using either a remote-controlled lockomotive engine, or one with a shielded cab for the crew -- just like they did for the ROVER/ NERVA tests at Jackass Flats (except you'd need at least two sets of parallel tracks, and special Schnabel-type flatbed cars to carry the heavy load.....)


 



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mauk2

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Wow, that is an amazing video!  You ROCK!


Just as a note, those boosters you are using might be based on the SRB, but would probably give less thrust for a longer time, because 15 SRB's on a 4000 tonner would be a pretty rough ride.


SRB's weigh about 650 tons each at launch, 15 of them would mass 9750 tons.  Adding in the 4000 tons for the Orion, that's a launch mass of 13,750 tons.  15 SRB's would have a launch thrust of 24,750 tons.  That'd be a whopping 1.8 gees off the pad, and since the SRB's weigh only about 100 tons empty, right before burnout the mass would be all the way down to 5500 tons, with 24,750 tons of thrust you'd be up to 4.5 gees.


It'd be a vicious ride! :D


Now, with a length increase of a third, they'd weigh about a thousand tons each, and if you formulated them to burn slower, you could lower the thrust to say 2.8 million pounds each.


That gets you to a launch weight of 19,000 tons with a launch thrust of  21,000 tons.  That gets you off the pad at a nice gentle 1.1 gees and peak acceleration right before burnout (assuming they weigh 150 tons empty) of 3.36 g.  Still pretty brisk, but not too much more than the Space Shuttle.


As a side effect, with a third more propellant and a burn rate  15 percent less, you get a burn time of 1.57 times as long, or three minutes instead of two minutes. 


You'd be WAY downrange and easily above the atmosphere with that much heft working for ya.  :D



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GoogleNaut

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...good analysis. When I saw Rhysy's conceptualization with 12 to 15 SRB's, I was shocked. The thought never occured to me to use SRB's for an Orion launch. It was a great idea, and one that I feel could actually work. It's simple and has just the right brutality to make me think it could actually fly.

You know, if you use 15 SRB's then you could easily make 3 of them 'air start' motors with 12 ground ignites. This in effect increases the boost time, reduces the g loads by using the wieght of three boosters as ballast, and also ensures your vehicle is 'way downrange' before you start lighting off 'eye popping' nukes!

This is why I love this website--it's full of new ideas, and that's always a good thing!


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