SM Fission Fragment Rocket

[Scotius]

Wohooo! Even better looking than basic version. Downloaded, and soon going to try it on Duna-going vessel.

[Mekan1k]

2-engine version looks amazing, has great thrust, and on 100% thrust tank is gone is 15 seconds. In space. With a monkey.

Okay, the 'with a monkey' thing was unnecessary, but it seems to get horrible fuel efficiency with the booster module.

I would recommend doubling the isp of both engines. (Yes, I did stick a metric TON of ion tanks and batteries on the thing, but I wanted to see if I could use the new module to get to the mun and back)

[Scotius]

Any afterburner is a fuel-guzzler. That's why most fighter jets use them only when it's really needed - it severely cuts down plane's range. If you want to go somewhere fast with this engine, build small, light ship. Like my Sparrow II scout vessel - it weights 16 tons in VAB, holds one kerbal, is unable to land and 1/3 of its weight is xenon. I build bigger Mun landers. But it can get to Duna without any problems, scan and map it and Ike, and return doing 5 minutes capture burn without afterburner I love this engine I'm trying to build an interplanetary shuttle using four FFR's to carry a proper lander to Duna, but booster needed to put it in orbit chokes my computer. I have to cut down both part count and weight of the whole ship.

[SasquatchM]

actually i was considering altering the xenon: accelerant ratio from 22:.4 to 22:1. I'll give this a shot and post a download link here to test if you'd like. The Isp of both engines is insanely high the way they are, so i dunno about raising them much.

Edited April 29, 2013 by SasquatchM

[SasquatchM]

Here is a mediafire link with the altered booster: http://www./?ggi22hrakwbsk32

[Scotius]

Thanks SM - i will try it tomorrow. I already have FFR-powered ship over Duna, so this one will go to Eve Anyways, i don't see a need to play with Isp. As long as you have to be creative to get best results out of engine, it means it's not overpowered. Currently it works best for lightweight scout ships that i use instead of probes. Because of FFR's weight and size it's hard to build a lander or space tug using multiple engines for combined thrust - or maybe its just my engineering skills are sub-par

[SasquatchM]

try leaving a sort of mother ship in orbit with the FFRs have you lander re-orbit and dock. I t may be a little more feasable

[Phantom Hoover]

you should totally follow this up with the nuclear saltwater rocket

[hoojiwana]

Nuclear Saltwater rocket wouldn't be feasible in KSP, it would essentially be unbalanceable with the game in it's current state. There would be very little reason to use anything else.

[SasquatchM]

That is a cool idea! Now if I just had something to base a model off of.

You are correct in that it would be somewhat game breaking though. The only real balancing factor I can see is if the engine and fuel were fairly massive.

[hoojiwana]

The thing with nuclear saltwater designs is that they wouldn't be stupidly heavy. They have a TWR that's not awful, and exhaust velocity that is just mindblowing for how much thrust they could put out. The real-life limiting factors for them are that they're only conceptual, safely containing the continuously exploding part, correctly cooling everything, and the very high cost of fuel/propellent. Those drawbacks can't currently exist in KSP, so such an engine would have no limiting factors.

[SasquatchM]

I have been trying to figure out a way to make an orion engine, but can't think of any way to make the pulsed thrust work. The rest you could do with a throttle based animation. Maybe make a generator that used electricity to very slowly made a resource, call it PulseUnit or something, have the capability to only store 1 unit in the engine, and have the engine burn the entire unit each time it fires? Not really sure how well that would work out.

Edited April 29, 2013 by SasquatchM

[hoojiwana]

I think there may have been an old plugin that produced pulsed thrust, I have no idea if it was lost with the forum outage or not though.

EDIT: Just had a poke through the Google cache of the forum, the old mod was called JOrion Pulsed Thrust Mod, by KwirkyJ.

Edited April 30, 2013 by hoojiwana

[SasquatchM]

Now, if i could find it to download that'd be nifty

[Scotius]

Wikipedia says this engine would be producing continuous thrust, not pulsed - maybe you are mistaking Saltwater with another design? And yeah, such engine would be pure awesomeness - in space there would be little reason to use anything else. Unless you make it too big and heavy to use on anything else than interplanetary mothership. Hmmm, since fission would continue in the exhaust, maybe such engine would be requiring huge radiation shield just behind the nozzle?

Ow. Derp. You are talking about Orion. Sorry, 7 a.m. and in the middle of the first cup - apparently my brain is still lagging

Edited April 30, 2013 by Scotius
Lack of attention.

[SasquatchM]

Looking at what I could find about the nuclear salt water engines, it sounds like anything radioactive is in the exhaust, which is travelling away from the craft at 66km/sec

[Scotius]

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. Fusion Driven Rocket albeit using similiar idea is more like pulse jet engine - and those were used to propel manned planes during WW II. So, if you want to mod high-tech, extremely effective pulse engine why not go with FDR? Also, its fuel supply of lithium should be easier to code than finite amount of A-bombs. I don't know anything about animations - but a sequence of High thrust - dropping thrust - minimal thrust - high thrust animations in a loop should be easier to do than short, cyclical but intensive spurts. But you are the expert

[SasquatchM]

Actually i know absolutely nothing about coding plugins, which is what i think it would take to get real pulsed thrust, but I may be able to get something working through the art of abusing game mechanics

[WhatsThisButtonDo]

try leaving a sort of mother ship in orbit with the FFRs have you lander re-orbit and dock. I t may be a little more feasable

Funny you should say that, after trying this engine out in Kerbal orbit on a few designs, it inspired me to make mother ships to send out to orbit the planets for docking, resupply, and staging for descents for exploration and habitats. I'm sure other people have been doing that for a while, but for me it was this engine that gave me the idea. Look forward to anything else you come up with.

[Scotius]

I have such ship on design board too. It uses 4 engines mounted on radially attached girders. It has two docking ports on both ends, so it can both push and tug the payload. Unfortunately i ran into a issue with booster stage - it got so big my game chokes on it, and i can't reach the orbit. I have to cut part count down apparently.

[SasquatchM]

If you really need to you can assemble the mother ship in orbit out of docked parts, use quantum struts to reduce sway once it is assembled

[Scotius]

Whew. I made it - finally. I had to place a lot of struts to keep my ungodly creation stable during the lift-off. Result is...adequate, i think. It can fly straight, have enough thrust to move jumbo tank around. Turn rate is kinda low, but it was to be expected. What i have to do, is find a way to move engine nacelles upwards, closer to the center of mass. It should make maneuvering easier, and docking stuff to rear dock will be less harrowing experience Today i will launch a lander, and try to reach Jool system.

[MaHuJa]

If you have the deadly reentry mod, you can use a tricoupler + 3x 1.25m heat shields + 3x FF engines for a fairly compact engine setup.

On the other hand, I've had problems with these engines suddenly, for no particular reason, losing all their fuel. In this 3-engine setup, one lost all its fuel very suddenly. I hadn't even hit the 10% mark for fuel usage. Then the other two did the same, together.

[SasquatchM]

Were you using the xenon injectors as well? The fuel use shouldn't be happening like that on the FFRs. the fuel is set up like SRBs so the fuel doesn't flow between engines. If you ignite either the FFRs or the Xenon injector system in any sort of atmosphere they do burn fuel much more quickly.. it shouldn't be that much more quickly though.

On the onther hand, FFRAccelerant is actually generated by the FFR for use in the XI, and is only a small quantity and flows like monopropellant, so the XI will burn through it FAST if the FFR is off.

Edited May 3, 2013 by SasquatchM

[Scotius]

I created anothe space tug yesterday - and i'm glad to say it's much better design. It's bigger - topping at 77 tons, but surprisingly maneuverable, even with a jumbo tank (half-empty) docked to bottom docking port. All thanks to raising four arms closer to the top of the ship, so the engines don't stick beyond CoM too much. Firing only FFRs i got 8 minutes burns on the way to Duna, while hauling 2000+ units of fuel onboard dedicated tanker vessel. Using afterburn mode i could cut the burning time down considerably. At the moment i have four FFR powered ships of various designs in space as far as Duna, and i haven't ran into any kind of bug you've mentioned MaHuJa. Maybe it's a conflict with another mod?