[amsat-bb] Re: What is wrong in the calculations ???

[Michael Zürch <dg1cmz@xxxxxx>]

Hi William,

checked it:

Vb = sqrt(2mu / r ) is the escape velocity for moon's gravity. Your equation
V,orbit = sqrt(u/r) represents the circular orbital velocity. But the
calculation you want to do is the first - the approaching of a vehicle from
lunar-transfer-orbit which is mechanically seen the same like an escape
orbit, so using formula "Vb" is correct.

Other oppinions?

73 de Michael, DG1CMZ!


----- Original Message -----
From: "William Leijenaar" <pe1rah@hotmail.com>
To: <amsat-bb@amsat.org>
Cc: <dg1cmz@freenet.de>
Sent: Saturday, January 17, 2004 12:55 AM
Subject: What is wrong in the calculations ???


> Hi AMSATs,
>
> I am doing some calculations with a E to M mission :o)
> No EME, but just EM hihi
> I didnt talk about m**n :o)
>
> On internet I found some interresting calculations, but after some
> investigation I find some problems.
> The calculations can be found on the following webpage:
>
>
http://hyperserver.engrg.uwo.ca/ilc-usn/Reports/LTVS/html/Mission%20Profile%
20and%20Functions.htm
>
> In the page the following can be found:
> "the velocity of the LTVS as it approaches the moon can be found by:"
>
> Followed by following formula
> -----------------------------
> Vb = sqrt(2u/Rb)             ** sqrt is square root
>
> From other formulas I have, it seems to me that the "2u" must be "u"
> My calculations:
> The following formulas I have used:
>
> 1: V,orbit = sqrt(R x g,orbit)
> 2: g,orbit = G x M / R^2
> 3: u = G x M
>
> When changing g,orbit of formula 1 we get:
> ------------------------------------------
>
> V,orbit = sqrt(R x (G x M / R^2) )
>
> Changing "G x M" in "u" gives:
> ------------------------------
>
> V,orbit = sqrt(R x u / R^2)
>
> And finally we get:
> -------------------
> V,orbit = sqrt(u / R) !!!!!!
>
> So where is the 2 comming from ???
> Maybe some other formula or other speed is calculated ???
>
> 73 de PE1RAH, in Peru, close to Machu Picchu :o)
> ---
>
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>
----
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