SRB - Assisted Craft (Eg S1 SRB, S2 Fusion Engine)

[SunJumper]

Imagine for a moment you've developed a fusion engine, that fuses, say, He3 and D, and expels He4 for thrust. This engine would produce incredibly hot gas (more than a few million degrees), and would also produce highly ionising alpha particles. Safe to say, you won't want this stuff anywhere near life.

So, what is the feasability of using a single SRB to lift this engine/fuel/payload to a high altitude (Testing with a not-quite balanced SRB gives a burnout altitude of about 8km), such that ignition of the fusion engine will not destroy the launchpad or all lifeforms nearby?

Also, what is the desired altitude for fusion engine ignition?

[Xeldrak]

Well, alpha radiation is no problem - it's reach is about 10 cm under normal atmospheric conditions. So the problem would be your hot gasses - well, the desired altitude (if your assisted start is needed) would heavily depend on the actual size and shape of the engine.

[Kryten]

How heavy do you imagine the fusion-powered stage to be?

[SunJumper]

Testing with a modified Jet engine gives an average ship mass of about 50 tons, for an 18 ton engine with a thrust of 4.5 MN

And the .cfg is:

// Kerbal Space Program - Part Config
// LV-T45 Liquid Fuel Engine
// 

// --- general parameters ---
name = FusionEngine
module = Part
author = C. Jenkins & Sunjumper

// --- asset parameters ---
mesh = model.mu
[B]rescaleFactor = 2[/B]


// --- node definitions ---
node_stack_top = 0.0, 0.7783, 0.0, 0.0, 1.0, 0.0
[B]node_stack_bottom = 0.0, -0.0, 0.0, 0.0, 1.0, 0.0[/B]


// --- FX definitions ---

fx_exhaustLight_blue = 0.0, 0.0, 0.0, 0.0, 0.0, 1.0, power
fx_smokeTrail_light  = 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, power
fx_exhaustSparks_flameout = 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, flameout

// --- Sound FX definition ---

sound_vent_medium = engage
sound_jet_low = running
sound_jet_deep = power
sound_vent_soft = disengage
sound_explosion_low = flameout

// --- editor parameters ---
[B]cost = 950000[/B]
category = Propulsion
subcategory = 0
title = Big Fusion engine
manufacturer = C7 Aerospace Division.
description = Built from the highest quality supermatter plates and solenoids, this part achieves superior thrust and even more superior efficiency.
// attachment rules: stack, srfAttach, allowStack, allowSrfAttach, allowCollision
attachRules = 1,0,1,0,0

// --- standard part parameters ---
[B]mass = 18[/B]
dragModelType = default
maximum_drag = 0.2
minimum_drag = 0.2
angularDrag = 2
[B]crashTolerance = 700
maxTemp = 3600000[/B]


MODULE
{
    name = ModuleEngines
    thrustVectorTransformName = thrustTransform
    exhaustDamage = True
    ignitionThreshold = 0.1
    minThrust = 0
[B]    maxThrust = 4500
    heatProduction = 700[/B]
    useEngineResponseTime = True
[B]    engineAccelerationSpeed = 2
    engineDecelerationSpeed = 2
    useVelocityCurve = False[/B]
    fxOffset = 0, 0, 0.74
    PROPELLANT
[B]    {
        name = Helium3
            ratio = 1
        DrawGauge = False
    }
    PROPELLANT
    {
        name = Deuterium
            ratio = 1
        DrawGauge = True
    }

    atmosphereCurve
     {
        key = 0 32235
        key = 0.3 30000
        key = 1 27000
     }[/B]

}

MODULE
{
      name = ModuleAnimateHeat
}

MODULE
{
    name = ModuleGimbal
    gimbalTransformName = thrustTransform
    gimbalRange = 1
}

MODULE
{
    name = ModuleAlternator    
[B]    RESOURCE
    {
        name = ElectricCharge
        rate = 2.8
    }[/B]
}
RESOURCE
{
    name = ElectricCharge
    amount = 0
    maxAmount = 0
}

What's in bold is the edited lines. This isn't really a jet engine, it just looks like one...

Edited May 10, 2013 by SunJumper

[nyrath]

SunJumper, did you read Dr. Slough's papers on Magneto Inertial Fusion?

http://msnwllc.com/propulsion-publications

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

The fusion fuel is compressed by lithium foil rings, which do a good job of containing the radiation. Then the lithium acts like propellant, , with much more mass than a thin stream of He4.

[magnemoe]

first will an fusion engine work in the atmosphere? if you use an beam of charged particles from an polywell or the classical torus they will be generated in an vacuum chamber air will get in thought the hole and the process will stop.

The second idea is an pulsed drive, it might work however the air might mess thing up, its also pretty low trust and require an separate reactor or solar panels to power it.

[Rune]

first will an fusion engine work in the atmosphere? if you use an beam of charged particles from an polywell or the classical torus they will be generated in an vacuum chamber air will get in thought the hole and the process will stop.

The second idea is an pulsed drive, it might work however the air might mess thing up, its also pretty low trust and require an separate reactor or solar panels to power it.

The idea on a Polywell SSTO is that you only use the energy in alphas from the p-b11 reaction, and you use that directly converted to electrical energy at very high efficiencies (>90%) through magnetic fields to drive electron beam guns to heat a propellant inside a magnetic nozzle in a separate chamber where the fuel injectors are. Neat, right? Only ~20% of the reaction needs to be actively cooled and/or emitted as neutron radiation. Thus the fusion chamber can remain a vacuum. Magneto-inertial, I dunno, but my gut tells me the design is meant for vacuum conditions.

Rune. On the edge of T/W, though, it needs wings.

[magnemoe]

The idea on a Polywell SSTO is that you only use the energy in alphas from the p-b11 reaction, and you use that directly converted to electrical energy at very high efficiencies (>90%) through magnetic fields to drive electron beam guns to heat a propellant inside a magnetic nozzle in a separate chamber where the fuel injectors are. Neat, right? Only ~20% of the reaction needs to be actively cooled and/or emitted as neutron radiation. Thus the fusion chamber can remain a vacuum. Magneto-inertial, I dunno, but my gut tells me the design is meant for vacuum conditions.

Rune. On the edge of T/W, though, it needs wings.

I see, had an similar scifi idea, in atmosphere you can heat air, and you can inject water to generate steam, useful to get high trust for an vertical landing and high up in the atmosphere before you open the reaction chamber, after flare-out in KSP.