Awesome, thanks!
On 4/7/23, Robert Steinke <robert.steinke@xxxxxxxxx> wrote:
On Thu, Apr 6, 2023 at 10:54 AM Alexander Mikhailov <
alexander.mikhailov@xxxxxxxxx> wrote:
When you run the numbers the energy density of modern batteriesquite well to the kinetic energy extractable from decomposed peroxide
compares
monoprop in a practical steam engine. I did a presentation about this
maybe
10 years ago at space access because when I looked at the numbers I was
floored by how good batteries are nowadays.
I'd definitely be very interested to look at that presentation.
My BOTE calculations for peroxide go like that: at ~50 atm liquid
output pressure amount of input peroxide to drive pumps is ~1/20 of
the total amount of peroxide, mass of pump hardware is negligible,
nothing to drop as too heavy.
What would be approximate numbers for electrical pumping system?
Alex
1 cubic meter of 85% H2O2 (1350 kg) pumped uphill against a dP of 5MPa
takes 5MJ of work. Here's a hobby battery with a "nominal" capacity of
1.8MJ
https://hobbyking.com/en_us/turnigy-high-capacity-battery-20000mah-6s-12c-drone-lipo-pack-xt90.html
Three of them weigh 7.9kg, 1/170 the mass of the peroxide.
Now, this is a back of the envelope assuming 100% efficiency and the
battery actually delivers its nominal capacity at a high discharge rate,
and not accounting for electric motor and pump hardware mass. But it's
still surprising that batteries are competitive with an H2O2 monoprop steam
engine.