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SM Fission Fragment Rocket

SasquatchM

By SasquatchM
in KSP1 Mod Releases

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MaHuJa

MaHuJa

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No XIs. And it's just a matter of engines' fuel supply instantly going from e.g. 9.97 to 0. I have no idea what triggers it, but whatever it is, it hit one engine (a couple km off the mun surface), and only later hit the other two (with kerbin orbit, not yet decaying).

Could be a mod conflict, I do have a lot of them.

I haven't given up on it, so I'll try more. If it happens again I'll try to figure out the conditions.

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nyrath

nyrath

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If forced to choose between Saltwater and Orion i would take Salty every time. For some reason this whole idea of propelling a spaceship by detonating atomic bombs (even small) near its tail looks bad to me

Ummmmm, I fear that you do not understand the nuclear salt water rocket.

Orion is a nuclear rocket driven by a series of detonations near its tail.

Nuclear salt water rocket is driven by a CONTINUOUS NUCLEAR DETONATION near its tail.

So the salt water rocket is worse.

If you have problems with detonating nuclear devices near the rocket's tail, it might be better trying detonating them in front.

http://www.projectrho.com/public_html/rocket/enginelist.php#id--Pulse--Medusa

Edited by nyrath
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Mekan1k

Mekan1k

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Ummmmm, I fear that you do not understand the nuclear salt water rocket.

Orion is a nuclear rocket driven by a series of detonations near its tail.

Nuclear salt water rocket is driven by a CONTINUOUS NUCLEAR DETONATION near its tail.

So the salt water rocket is worse.

Depends on your point of view.

The concussive impacts of the Orion system can cause damage to the rocket, and a lot of energy is release sideways and lost in the detonation of the bombs.

Nuclear salt water rockets end up with a 'continuous' explosion, yes, but it is directed, so a lot of extra energy gets used for propulsion instead of being perpendicular to the point of detonation, making it more energy efficient. Since it is 'continuous' as well, in conjunction with the water as reaction mass, the rocket becomes more efficient and safer, and the structure does not have to deal with the concussive shockwaves of the nukes....

From my point of view, the Nuclear Saltwater rocket is much safer, if only because the method requires less nuclear explosives.

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Scotius

Scotius

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Any jet engine is powered by continuous explosion of its fuel. :) Just like Mekan1k wrote, my main gripe with the Orion is frequent stress on the spaceship's frame it creates, and huge waste of energy. When you want to roll a cart from one place to another, repeatedly smashing it with a huge hammer is probably one of the worst methods of doing that. When Orion drive was conceived we did not had any other reliable method of creating comparably high thrust, so it was quick and dirty solution to a problem. Today we have similiar problem with fusion drive. We can't build fusion torch engine that would produce high, continuous thrust. Best we can do now is Fusion Driven Rocket, which is basically a return to Orion idea with its scheme of detonating small portions of fusion fuel to produce pulsed thrust. Since the way to controlled, stable fusion is still long, then who knows - maybe one day we'll build an FDR as a quick, dirty solution :)

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nyrath

nyrath

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Depends on your point of view.

The concussive impacts of the Orion system can cause damage to the rocket, and a lot of energy is release sideways and lost in the detonation of the bombs.

Ummm, no, that turns out not to be the case.

The propulsive charges in an Orion Drive are nuclear shaped charges. About 85% of the energy from the nuke is directed into the pusher plate.

If they were not shaped charges, only about 10% would hit the plate.

Details on my website

http://www.projectrho.com/public_html/rocket/spacegunconvent.php#id--Nukes_In_Space--Nuclear_Shaped_Charges

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Mekan1k

Mekan1k

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Ummm, no, that turns out not to be the case.

The propulsive charges in an Orion Drive are nuclear shaped charges. About 85% of the energy from the nuke is directed into the pusher plate.

If they were not shaped charges, only about 10% would hit the plate.

Details on my website

http://www.projectrho.com/public_html/rocket/spacegunconvent.php#id--Nukes_In_Space--Nuclear_Shaped_Charges

Even with shaped charges, alot of energy gets lost to the 'plating' behind the charge. Think about the common military device known as a 'claymore' anti-personnel mine. Now, this is a steel plate with a shaped charge on the front, and some ball bearings or other shrapnel on top of the charge, similar to what is shown on your website. When it fires, the ball bearings go shooting away, and the steel plate becomes distorted and fractured. Similar to a shaped charge of any kind, it is never perfect. However, you have to understand that the casing around the nuke would flash-vaporize or become incredibly distorted, taking up a large chunk of the energy that could be used for propulsion. Similarly, since it is directing energy away from the center of mass of the device, the remnants of the explosive would gain momentum, rather than the ship.

Let's go back to the claymore analogy- usually it has spikes on the bottom, that can be jammed into a surface to provide purchase upon detonation. However, if you cut off the spikes, placed it on the ground, and detonated it, the mine would fly off in the opposite direction of the explosion. Similarity, the nuclear bomb would need an equal force preventing it from moving in relation to it's initial position upon detonation. Yes, you could use a charge that is shaped to fire in two directions at the same time, but that a minimum of 50% of the energy of the detonation lost. This is due to, well, all of the laws of momentum.

Without a force opposing the direction of the main blast, the total momentum of the propellant would be equivalent to the total momentum of the charge, and even in the optimal configuration, where the mass of propellant is equivalent to the mass of the casing, the centroid speed of the propellant would be equivalent to the overall speed of the casing away from the point of detonation.

Anyway, when the Orion concept was first developed the concept was brought up on the unshaped nuclear charge, not the shaped ones. So really, it does not matter anyway, as the Orion system is still LESS EFFICIENT than the Nuclear Salt-Water Rocket.

EDIT- Spelling corrections

EDIT- Just to let you know, I am now bookmarking that site. Thanks for the link! :cool:

Edited by Mekan1k
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15nelsoc

15nelsoc

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I am having the same issue as Mahuja where my thorium will go from 9.98 to 0 after about 2 minutes of burn. I can't figure out what could be causing it besides maybe something to do with altitude.

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MaHuJa

MaHuJa

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I've had it happen again, twice. Including one where I think it happened to some other engine, I think maybe it was stock engines, and probably connected to using "x" to cut off engine power.

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Dompyongyang

Dompyongyang

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Hello all. First off, this add-on is fantastic. I really like it and thanks for making it!

I hae a question regarding the instructions on the "how to use" tab @ http://kerbalspaceprogram.com/sm-fission-fragment-rocket/. It states "The Xenon injector is set up as a separate engine, so make sure to set up your action groups appropriately", now, I have no idea how to do this. I have noticed the action groups tab in the VAB but I don't know what to add in there and I am unclear on how to setup an action group for this add-on or even why I should.

Can anyone give me a few pointers on how to set it up?

Any help will be highly appreciated and thanks in advance!

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Scotius

Scotius

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When you have ship ready, click on the Action Groups icon. You should get a tab with Abort, Stage etc positions. Those relevant are called Custom 1-2-3...Click on the engine (it should highlight blue), pick 'Toggle' option under engine's name, then on Custom 1 tab until 'pip' thingy lights up. Now return to Parts sections and you're ready to go :) You can switch engine On/Off using '1' button (above letter keys, not on numeric pad). Use it on Xenon Afterburner of course. Couple of advices: it heats. A lot. Think Mainsail attached straight to orange Jumbo tank. If it overheats, it WILL explode - neatly separating rest of the engine, thus stranding you in space. I use Afterburner only during huge burns, at about 3/4 throttle (switching it On/Off with action group key). Don't let MechJeb use the Afterburner - it leads to explosions, separations and stranding :) Oh, and there is a small matter of "Vanishing fuel bug" - quicksave before using FFR engines.

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wasmic

wasmic

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What exactly is the thrust?

50 kN, I think. Not much, but it can go on practically forever (many hours days of burning without refuelling. Which is good, as it can't be refuelled IIRC. Anyway, it's got a nice sound and great looks. I can only recommend this mod.

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