[Professor Mega-Mind (OP)]

☆For compressed version - Pg. 5
 ** Steam-Punk Engine
Can an Impulse Engine be made.
 In a nutshell , yes !  The real question is ; can a strong , extremely high ISP (above 50K) reaction engine , be built ?  No nuclear-thermal , or ion engines , fit the bill .  They fall short on at least one count .  Nuclear- explosion engines (including pellet) are impractical , & fusion is a pipe dream .  What is needed is a nuclear-mechanical drive .  This would be a nuclear-powered  high pressure system , fielding 1 million psi.+ , & yielding exhaust velocities approaching 1M mph ! The pressure-chamber would be held at 250°F .  This would keep the methane liquid, but the metal strong . Solar power& capacitors could be used , but compact nuclear reactors would be much more powerful & effective .  High power/efficiency would enable much more shielding , & much shorter transit times .  Very long electro-thermal  exhaust pipes would magnify the exhaust velocity. Coiled versions would work for SSTO shuttles .  This propulsion architecture would give mankind the Solar system right off the bat . 
As the cartoon character used to say ; " Oh Magoo , you've done it again ! ".                P.M. 
**Note : Bypass pg. 4 .**
__________________________________
》Compare/contrast systems at : What is the best spaceship design?
www.thenakedscientists.com/forum/index.php?topic=74813.new;topicseen#new 
> Also <
NSF. thread : How does rocket-thrust work in the vacuum of space?
Link at 28976.0  .
My replies begin at # 12 .
》My post #1 : quora.com/How-do-impulse-engines-work/answer/Derek-Hendricks-7?ch

[Kryptid]

The pressure-chamber would be held at 250°F .  This would keep the methane liquid, but the metal strong .

Methane cannot be a liquid at 250 degrees Fahrenheit. That's above its critical temperature.

A nuclear fission rocket engine was developed and successfully tested back in the 60's: https://en.wikipedia.org/wiki/NERVA

[Professor Mega-Mind (OP)]

Ah Mr. Kryptid , what a pleasure to hear you again !
Normally that would be the case , but at 1 Million + psi the CH4 will turn to hot ice , below ~250F°.  You would then need to shovel it like coal ! 
Please critique further , 2.5 heads is better than 1.5 .          P.M.

[Kryptid]

Normally that would be the case , but at 1 Million + psi the CH4 will turn to hot ice , below ~250F°.

"Hot ice" is not a liquid.

You would then need to shovel it like coal !

How is a person going to surviving in a 1 million psi environment to shovel it? Also, existing rocket combustion chambers operate between 150 to 3,000 psi (even the NERVA nuclear rocket had a nominal.chamber pressure of 450 psi). How do you propose building an engine to withstand beyond 1,000,000 psi without making it excessively thick and heavy?

[Professor Mega-Mind (OP)]

Good points , manly-man !
If I let it go from liquid to ice , it would clog up & go boom !  Also , it damned sure better be real heavy ; the reinforcement necessary for that much pressure is huge .  Only someone standing behind the engine exhaust would experience it's rediculous power , it is meant for a large , SSTO spaceplane . Let us measure ; One 200MW SMR - 40 ft. X 20 ft. by 20 ft. .  One Nuclear
   Compression Drive - 20ft.X20ft.X 20ft. .  One 4,000gal. LNG tank - 10 ft. X 10ft. X 20ft. .
Craft size - Venture Star class .
Gross Take-Off Weight - 500k lbs.
Launch locations - Remote .
OK , spread the good mews !    P.M.

[Kryptid]

Good points , manly-man !
If I let it go from liquid to ice , it would clog up & go boom !  Also , it damned sure better be real heavy ; the reinforcement necessary for that much pressure is huge .  Only someone standing behind the engine exhaust would experience it's rediculous power , it is meant for a large , SSTO spaceplane . Let us measure ; One 100MW SMR - 40 ft. X 20 ft. by 20 ft. .  One Nuclear
   Compression Drive - 20ft.X20ft.X 20ft. .  One 4,000gal. LNG tank - 10 ft. X 10ft. X 20ft. .
Craft size - Venture Star class .
Gross Take-Off Weight - 500k lbs.
Launch locations - Remote .
OK , spread the good mews !    P.M.

Where are you getting these numbers from? What method did you use to calculate the spacecraft's weight? How did you calculate the exhaust velocity? Did you calculate how much thrust would be produced? More importantly, is the resulting thrust-to-weight ratio high enough to get the ship into space? Is it demonstrably better than prior nuclear rocket technologies like NERVA? How would you get it past the political issues that prevented nuclear rockets from being sent to space in the first place?

[Professor Mega-Mind (OP)]

Mista Kryptid , all numbers used are extrapolations based upon known facts , figures ,& databases. Exhaust  velocity, for example, is based on many tables of pressure vs escape velocity , including things like rupturing hi-pressure vessels .  The important thing is to recognize the non-linear nature of the relationship,  and extrapolate accordingly .  Weights of high-powered SMRs w/partial shielding, no pressure-vessel, & light-weight components should total ~100klbs w/o radiators .
200MWshould net ~100klbs of thrust .
The 5 to 1 power/weight ratio is aerospace standard . The craft should T.O. & climb quite well , picking up speed steadily , until it exceeds Mach 24 ( O.V. ) .  ISP would be ~50 times SSME .
The political issues would be mitigated by having it travel over the ocean , not land .  The modern public is much less fearful of N.- Power than in the past .  It is now manageable .
Alright , space-trucking it is !    P.M.

[Kryptid]

Please show your math (especially for the claim that your design has a specific impulse 100 times that of NERVA).

[Professor Mega-Mind (OP)]

                   Cliff Notes
SSME pressure : 4,000 psi.
Exhaust  Velocity : 10,000 mph
Heavy gas cylinder : 10,000 psi.
Rupture Ex. Velocity : 30,000 mph
*relatively wide throat allows more layered exhaust & higher velocities.
extrapolating for lightweight CH4 yields 1M.mph at 1M.psi .
Okay , done for day !..................P.M.

[Kryptid]

                   Cliff Notes
SSME pressure : 4,000 psi.
Exhaust  Velocity : 10,000 mph
Heavy gas cylinder : 10,000 psi.
Rupture Ex. Velocity : 30,000 mph
*relatively wide throat allows more layered exhaust & higher velocities.
extrapolating for lightweight CH4 yields 1M.mph at 1M.psi .
Okay , done for day !..................P.M.

And what equation(s) did you use to turn those numbers into an exhaust velocity of 1 million miles per hour and a specific impulse of 82,500?

[Professor Mega-Mind (OP)]

Graph , and extrapolate for ballpark

[Kryptid]

Graph , and extrapolate for ballpark

That tells me nothing as to the accuracy of your numbers. You've got to give us more than that to work with.

[Professor Mega-Mind (OP)]

Who is us ?  You & Gunter Zoloff ?
If you must have a formula , try Navier-Stokes: `m`=pA♤T/z .
My process is extrapolation from known values .  I will show it here step-by-step .
Step 1 : Sample a multitude of rocket systems . Note chamber pressures , throat diameters , gas densities , and flow velocities  .
Step 2: Sample hi-pressure vessel ruptures . Note pressure , hole size, gas density , and escape velocities. 
Step 3 : Establish P/V pattern .
Step 4 : Extrapolate from 10k.psi to 1 Million psi .
Step 5 : Compensate for lighter weight methane reaction mass .
Step 6 : Calculate for different pressure chamber orifice sizes .
Conclusion : Large orifice sizes should yield ~1Mmph. @ 1M.psi. , ISP ~45k.sec. , thrust ~25M.lbs. .
Smaller orifice sizes would greatly reduce these values , but electrothermal " afterburners " would greatly increase them .
Alright,it's an aerospacepropulsion breakthrough !
I will take your congrats. now . P.M.

[Kryptid]

Who is us ?  You & Gunter Zoloff ?

Anyone else who happens to read this thread.

If you must have a formula , try Navier-Stokes: `m`=pA♤T/z .
My process is extrapolation from known values .  I will show it here step-by-step .
Step 1 : Sample a multitude of rocket systems . Note chamber pressures , throat diameters , gas densities , and flow velocities  .
Step 2: Sample hi-pressure vessel ruptures . Note pressure , hole size, gas density , and escape velocities. 
Step 3 : Establish P/V pattern .
Step 4 : Extrapolate from 10k.psi to 1 Million psi .
Step 5 : Compensate for lighter weight methane reaction mass .
Step 6 : Calculate for different pressure chamber orifice sizes .
Conclusion : Large orifice sizes should yield ~1Mmph. @ 1M.psi. , ISP ~45k.sec. , thrust ~25M.lbs. .
Smaller orifice sizes would greatly reduce these values , but electrothermal " afterburners " would greatly increase them .
Alright,it's an aerospacepropulsion breakthrough !
I will take your congrats. now . P.M.

Telling me "it's such-and-such because I extrapolated" is meaningless because that doesn't tell me if it is accurate. I don't know if your interpretation of the graphs and numbers are even correct. Show me those very same graphs and/or equations that you used to get your numbers.  I want to see each and every step in the math that you used to get from your starting assumptions to your final numbers.

[Professor Mega-Mind (OP)]

Yaah mahn , Ya needs an aerospace engineer mahn !  I'm a system designer , not a rocket scientist.I never had the patience ta crunch formulas like dat ! I tell you whut , why don't you put on dem sneaks , ahnd chase down da nearest pencil-on-da-ear nerd walkin' down da street , cuz I not be wone , cuz !  10 gits ya one my numbas be ballpark dough !
Adios , #s jockey !...............P.M.

[Kryptid]

Yaah mahn , Ya needs an aerospace engineer mahn !  I'm a system designer , not a rocket scientist.I never had the patience ta crunch formulas like dat ! I tell you whut , why don't you put on dem sneaks , ahnd chase down da nearest pencil-on-da-ear nerd walkin' down da street , cuz I not be wone , cuz !  10 gits ya one my numbas be ballpark dough !
Adios , #s jockey !...............P.M.

So in other words, you have no idea if your claims are valid.

[Professor Mega-Mind (OP)]

I'm sure , buut , you not be sure ! 
 Just track down a graduate student and give him/her this thread .  Have them run realistic #s through the relevant equations .  Then You'll be sure .  Adios ,   P.M.

[Kryptid]

I be sure , buut , you not be sure !  Just track down a graduate student and give him/her this thread .  Have them run realistic #s through the relevant equations .  Then You'll be sure .  Adios ,   P.M.

It's not up to us to prove or disprove your claims. That's your job. So far, you have not done so. All you have done is said that you got your results by extrapolations. You think we are just going to take your word for it?

[wolfekeeper]

What is needed is a nuclear-mechanical drive .  This would be a nuclear-powered  high pressure system , fielding 1 million psi.+ , & yielding exhaust velocities approaching 1M mph ! The pressure-chamber would be held at 250°F .

No.

To get high exhaust velocities, you need high temperature differences (Carnot efficiency rules these kinds of situations). Pressure is helpful to allow you to make use of very high temperatures, but makes no difference on its own.

[Professor Mega-Mind (OP)]

You are thinking of combustion-powered projectiles , I am using a continuing shockwave .  Their velocity is definitely pressure-driven .  Combustion is so weak !