Non-Dimensional Model for Optimal Horizontal Launch Efficiency

[arkie87]

Sorry, I'll get to your question in a moment. Just wanted to post this for you first.

http://i52.photobucket.com/albums/g13/GoSlash27/CP2B_zps1374ebdf.jpg

I hope that works for you. Let me know if there are any errors.

Yeah, i was just working on revising graph, myself... but yours is better... hehe

Thanks!!

[arkie87]

Sorry, I'll get to your question in a moment. Just wanted to post this for you first.

http://i52.photobucket.com/albums/g13/GoSlash27/CP2B_zps1374ebdf.jpg

I hope that works for you. Let me know if there are any errors.

Can you revise to say Initial Thrust to Weight Ratio (to be clear it's not changing with time or mass)

Also, can you change v_0 to v_orb and maybe define v_orb as sqrt(g*R)

[GoSlash27]

So...

Yeah, I could confirm that I didn't go anywhere at first during my tests. I didn't record launch altitude or flight duration previously, so I'll rerun it.

I'm going to run 2 launches today to try to pin down how much of the error is altitude (if any) vs. sidereal rotation.

I'll do another launch from the Mun (rotation 9 m/sec), and one from Eeloo (68m/sec). Both as close to 1.0 t/w as I can get them.

Best,

-Slashy

- - - Updated - - -

Can you revise to say Initial Thrust to Weight Ratio (to be clear it's not changing with time or mass)

Also, can you change v_0 to v_orb and maybe define v_orb as sqrt(g*R)

Yessir. I'll get on that right away.

Best,

-Slashy

[arkie87]

So...

Yeah, I could confirm that I didn't go anywhere at first during my tests. I didn't record launch altitude or flight duration previously, so I'll rerun it.

I'm going to run 2 launches today to try to pin down how much of the error is altitude (if any) vs. sidereal rotation.

I'll do another launch from the Mun (rotation 9 m/sec), and one from Eeloo (68m/sec). Both as close to 1.0 t/w as I can get them.

Best,

-Slashy

I recommend designing for TWR >>1, using hyperedit to get into orbit around desired body, using infinite fuel to land with high TWR, and then turning infinite fuel off once landed and limitting throttle to desired TWR

(just make sure your craft has enough deltaV to get into orbit given it's predicted efficiency -- ive made that mistake more than once!)

Thanks for testing!

- - - Updated - - -

Yessir. I'll get on that right away.

Best,

-Slashy

Thanks again!

[GoSlash27]

Direct link http://i52.photobucket.com/albums/g13/GoSlash27/CP2C_zps4c88655e.jpg

[GoSlash27]

arkie,

Not a problem. I'm as interested in seeing where this winds up as anybody

Best,

-Slashy

[arkie87]

Capital G is vague -- could be referring to gravitational constant or gravitational acceleration... perhaps we should use:

V_orbital = sqrt(mu/R) where mu is standard gravitational parameter G*M?

[GoSlash27]

Capital G is vague -- could be referring to gravitational constant or gravitational acceleration... perhaps we should use:

V_orbital = sqrt(mu/R) where mu is standard gravitational parameter G*M?

... but of course then we'd have to define mu as G*M.

I don't mind doing it (it's your plot). I can do either, so just let me know.

Best,

-Slashy

[arkie87]

... but of course then we'd have to define mu as G*M.

I don't mind doing it (it's your plot). I can do either, so just let me know.

Best,

-Slashy

mu is less vague, since i've only seen mu in this context mean standard gravitational parameter

capital G usually means gravitational constant, not acceleration due to gravity, which is lowercase g.

[GoSlash27]

Okay, I'll make it mu then.

Best,

-Slashy

[GoSlash27]

direct link http://i52.photobucket.com/albums/g13/GoSlash27/CP2D_zpsdad6f965.jpg

Best,

-Slashy

[GoSlash27]

Eeloo test results are in, and if I read the chart correctly, I didn't outperform the model.

At launch:

M=2.35t T=4kN Isp=290s T/W= 1.01 alt=1,971m t= 04:00

At circularization:

M=1.71t Vo=568.7m/sec alt=20,048m t=31:48

DV expended= 905 m/sec

efficiency= .629

et=27:48

On to the mun!

-Slashy

[GoSlash27]

And Mun test results are in.

At launch:

M=2.43t T=4kN Isp=290s t/w=1.01 alt=2,361m t=30.00

At circularization:

M=1.70t Vo=547.5 m/sec alt=10,009 t=52:31

DV expended= 1,017 m/sec

efficiency= .538

st= 22:31

If I read the chart right, I way *under* performed compared to the chart this time.

Best,

-Slashy