Hohmann equation help

Solistics · Apr 16, 2009

I'm having some slight difficulties in calculating the delta-v in a hohmann transfer equation. I used the equation from wikipedia (which i hope is correct) but whenever i replace the variables i get an extremly small delta-v, is this normal???

[tex]\Delta[/tex]v=[tex]\sqrt{}(\mu/r1)[/tex]*([tex]\sqrt{}(2*r2/(r1+r2)[/tex]-1))

r1=6374000 meters
r2=405500000 meters
[tex]\mu=9.814[/tex]

my final result was 0.00122149m/s
it seems like a really small number, is this right or i'm i doing something really wrong?

i attached an excel sheet to show you my work.

thanks in advance

Janus · Apr 16, 2009

Solistics said: ↑

I'm having some slight difficulties in calculating the delta-v in a hohmann transfer equation. I used the equation from wikipedia (which i hope is correct) but whenever i replace the variables i get an extremly small delta-v, is this normal???

[tex]\Delta[/tex]v=[tex]\sqrt{}(\mu/r1)[/tex]*([tex]\sqrt{}(2*r2/(r1+r2)[/tex]-1))

r1=6374000 meters
r2=405500000 meters
[tex]\mu=9.814[/tex]

my final result was 0.00122149m/s
it seems like a really small number, is this right or i'm i doing something really wrong?

i attached an excel sheet to show you my work.

thanks in advance

The problem is your value for [itex]\mu[/itex]

[tex]\mu = GM[/tex]

Where G is the universal gravitational constant and is equal to

6.67300 × 10^-11 m³ kg^-1 s^-2

and M in this case is the mass of the Earth, or 5.97 x 10²⁴ kg

so

4.651 X [itex]10^{14}m^3 s^{-2}[/itex]

Solistics · Apr 16, 2009

thanks for that correction.

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Hohmann equation help

Solistics

Attached Files:

delta-v.xls

Janus

Solistics

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