To illustrate that last point with a comparison: let’s take the Merlin 1C or 1D
combustion chamber only.
It’s small enough to fit under the bonnet of just about any car on the road and
probably light enough to be carried by a single man.
Propellants LOX:PR1 at ~2.36 O:F ratio
Feed rate: 140Kg/s (for the 1C say)
Now for that propellant combination I calculate a c* of ~1690 m/s at optimal
mixing
So, specific E Joules/Kg = (1690^2)/2 = 1430823
So incorporating flowrate 1430823 * 140 = 20,031,521 J/Kg
Converting to Power = ~20 MW
Note: that’s just the chamber only.
Now compare to a super-duper $mega sports car:
What, they max out at about 1000HP? Which is ~0.75MW?
That’s with an engine that’s substantially larger and much much heavier.
Feel free to correct any of my BOE calcs..
Troy
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of Andrew Burns
Sent: Friday, 11 December 2015 5:17 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Closing the loop on rocket engines
There are several differences between rocket engines and car engines that are
key to this discussion:
- Rocket engines need only work for a few minutes at a time before being thrown
away (generally)
- Rocket engines operate with very tightly defined propellants at controlled
temperatures and pressures and within a very narrow operating window
- Rocket engines are normally essentially binary, on or off, they're not
normally dynamically throttled
- Rocket engines have an absolutely immense thrust/power to weight ratio
compared to car engines and are accordingly so much more highly stressed