Aeronaut wrote:
I’m reading a 100% duty cycle assumption into both the FF and the VASIMR,

That is the fate of nuclear-electric tugs… never a
break 🙂

Aeronaut wrote:
as well as 2 distinctly separate cooling challenges.

Apparently they have the supercon cooling
problem in hand. The article mentions 10-12 cryo-
coolers each lifting 15 watts from a VF-200 in flight
mode.

That would mean that they expect that 180 watts of
cooling will serve to handle the thermal leakage of
one VF-200 in operation.

That means 4 such engines would require less
than one kilowatt of cooling to keep the supercons
superconning.

The coolers for the VF-200 are to be custom-built,
but the specs for the referenced Cryo-Tel units say
the operating temp is -196 C while the output side
needs to be at 70 C or less.

The VASIMR supercons need to be at -233 C so
the output might have to come down. Let’s say
degree for degree so that the output side needs to
be at 33 C.

That’s not a problem… that’s some fancy trim
around the edge of the main radiator 🙂

So the engines can stay at 100 percent?

Now handling the thermal output of the rest
of the VASIMR drive is of the same order of
magnitude as the DPF (remember the DPF is
running at .86 MWe) so I was hoping to have them
on the same coolant line. If the DPF can handle
being at 300 C then perhaps we can cool the
drives first and then pipe it into the DPF.

But at this stage, before these latest supercon
modifications, there doesn’t seem to be any
showstoppers. The essential numbers for the main
radiator were:

temp (c) 300
area needed (m2) 188
mass (tons) 1.88
rejection (MWt) 0.98

… adding the needed stuff for the supercons won’t
change it that much… that is assuming my basic
assumptions were viable in the first place… 🙂