[AR] Re: Closing the loop on rocket engines

  • From: "Monroe L. King Jr." <monroe@xxxxxxxxxxxxxxxxxx>
  • To: arocket@xxxxxxxxxxxxx
  • Date: Thu, 10 Dec 2015 18:32:20 -0700

We tried that too! But the DECELERATION was detaching retinas :P lol

We where doing that back in my 20's until our driver started suffering
from this. That's what killed peroxide dragsters that and the
price/availability of peroxide.

The trap speeds where well over 400 mph.

Anyway onward and upward. I can say once you top out on IC engines and
turbines (what I did in the Navy) there's just no place to go but UP!

The Antietam had 4 LM2500's = 80,000 shaft HP

So I guess you can see why I choose to go the turbopump route.

I've got some backing and I have nearly a full shop now so the next
coupla years should be interesting at least :)

-------- Original Message --------
Subject: [AR] Re: Closing the loop on rocket engines
From: "Troy Prideaux" <GEORDI@xxxxxxxxxxxxxxxx>
Date: Thu, December 10, 2015 6:07 pm
To: <arocket@xxxxxxxxxxxxx>


Dunno I'd count that as "automotive" though... More like a rocket ship on
wheels :P

Troy

-----Original Message-----
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of Monroe L. King Jr.
Sent: Friday, 11 December 2015 12:00 PM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Closing the loop on rocket engines

Try out some 10,000hp action https://www.youtube.com/watch?v=CN4uAQzI1rs

Rocket guy's are cool don't get me wrong. But this is where I'm coming from.

-------- Original Message --------
Subject: [AR] Re: Closing the loop on rocket engines
From: "Troy Prideaux" <GEORDI@xxxxxxxxxxxxxxxx>
Date: Thu, December 10, 2015 5:08 pm
To: <arocket@xxxxxxxxxxxxx>


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

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