[AR] Re: Nuclear Hydrogen Thruster
- From: "Ray Rocket" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "ar0cketman" for DMARC)
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Sat, 9 Jun 2018 20:24:20 +0000 (UTC)
I was with you until you proposed pumping 10KPSI with a centrifugal pump. That
kind of work is best left to a piston pump or similar.
On Saturday, June 9, 2018 11:07 AM, Craig Fink <webegood@xxxxxxxxx> wrote:
New Horizon Probe propulsion design was driven by History, looking into the
past when NASA had Rocket Scientist willing to take a chance and figure out an
interplanetary propulsion system. But what if New Horizon had not been
restricted to History, but was allowed to look forward into the future .
On Thu, Jun 7, 2018 at 10:17 AM Nels Anderson <nels.anderson@xxxxxxx> wrote:
On 2018-06-07 10:42 AM, Craig Fink wrote:
I wish they had put one of those one the New Horizons probe, low
thrust mid-course corrections, hi thrust planetary burns. Sounds like
it was made for planetary probes.
> On Thu, Jun 7, 2018 at 9:30 AM Henry Vanderbilt
> <hvanderbilt@xxxxxxxxxxxxxx <
mailto:hvanderbilt@xxxxxxxxxxxxxx>> wrote:
Maybe it would be better to heat the H2
resistively, though that is not nearly so sexy. And one cannot help
noting that resistojet's appeal is limited to a few special situations.
Your right, what if NASA had put a resistojet onboard, what whould it look
like?
First, the power source for the arc jet, has to be nuclear as that was the
chosen power source for New Horizons. The engine must use on average of less
than 200 watts of power of nuclear origin.
Propellant, Hydrogen by far the best propellant for the job. Hydrogen is
"Shelf Stable" at 3 K temperatures of deep space, Hydrazine is not and requires
temperature control of the entire system to keep it from freezing. Passive "Sun
Shield" is all that is required to stop thermal radiation heating. Space is the
perfect Dewar so the pressure in the Hydrogen tank can be kept very low (vapor
pressure of Hydrogen at the boiling point of Helium), resulting in very light
weight storage tank, unlike the much heavier high pressure tank and
pressurization system of the Hydrazine.
New Horizion's mission profile requires 2 types of burns, one for mid course
corrections, one for planetary slingshots.
Mid-course correction type burns being the preferred mode of running, a pulsed
arc-jet that can be repeated for years and years. Extremely high ISP, low
thrust, able to run on 100 watts or less supplied the nuclear power supply.
Sounds like a fun design point for the engine.
Planetary Slingshot type burn being the short large thrust mode deep within
gravity wells. Low ISP (300 to 600) high thrust, blow-down mode so to speak
using an electric powered centrifugal compressor to bring the Hydrogen
propellant up to pressure (variable 100 to 10,000 psi). Two design points for
one engine, sounds like fun.
Battery, yes this engine is going to have a "Shelf Stable" battery to make the
trickle charger useful for the pulse arc-jet and power the pump. Shelf Stable
at 3 K temperatures, superconductor storage works great at Liquid Hydrogen
temperatures, so the battery goes in the the Propellant tank, that works.
Battery capacity, may as well make this extremely light weight low pressure
hydrogen tank do double duty by choosing the right material to build it, to
enhance and reduce the amount of superconductor required to size the battery.
Fe, hydrogen annealed Iron tank, metal of choice, to increase the inductance of
the superconductor loop of wire attached to the inside of the Hydrogen Tank.
Pulse Arc-Jet pressure tank, sized for one pulse of the Mid-course correction.
Liquid Hydrogen is pumped into the extremely small 10,000 (or more) psi engine
tank. This tank is heated by the nuclear battery, over time, bringing it up to
pressure ready for the Arc-Jet pulse where all the energy stored in the
superconducting loop is routed thru the Arc-Jet sending the 10,000 psi
extremely hot Hydrogen on its way. Not sure exactly what the ISP of this engine
would be, but I suspect it might be rather high.
Planetary Slingshot, blow-down mode. The Arc-Jet is turned off, all the energy
of the superconducting storage loop is needed to power the Electric pump to
bring the Liquid Hydrogen up to engine pressures. The valves of the 10,000 psi
arc-jet header tank are left open, this mode is running on pump pressure and
thermal mass heating supplied by the Nuclear Battery. Yes, may as well make
that heavy Nuclear Battery do double duty, just like the Iron Hydrogen tank.
Temperatures and pressure are much lower, but thrust is much higher and can be
sustained until the Nuclear Battery temperature drops to low.
Now that would be a sexy engine for deep space missions like New Horizon.
Craig Fink
WeBeGood@xxxxxxxxx
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