Apollo 8 - Navigation musings

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PHXPhlyer
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Re: Apollo 8 - Navigation musings

#21 Post by PHXPhlyer » Sun Feb 23, 2020 12:38 am

Just finished reading "Carrying The Fire" by Michael Collins.
Not too technical but a good read.
Pulls few punches regarding fellow astronauts.

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Re: Apollo 8 - Navigation musings

#22 Post by PHXPhlyer » Sun Feb 23, 2020 12:41 am

Sidevalve:
Read it and agree. :-bd

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Re: Apollo 8 - Navigation musings

#23 Post by OFSO » Sun Feb 23, 2020 6:17 am

A small correction. Vehicles lifting a body into equatorial earth orbit do not rise vertically. In order to take advantage of the earth's rotational speed a y axis shift to the east is made shortly after lift off. This is why launch sites are as near as possible to the equator where the perceived rotational speed of the earth is at a maximum. Polar insertions launch directly south, there is also a y axis rotation, but for different reasons, and they lift smaller payloads for the same fuel expended as they cannot take advantage of the earth's rotation.

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Re: Apollo 8 - Navigation musings

#24 Post by TheGreenGoblin » Sun Feb 23, 2020 9:18 am

OFSO wrote:
Sun Feb 23, 2020 6:17 am
A small correction. Vehicles lifting a body into equatorial earth orbit do not rise vertically. In order to take advantage of the earth's rotational speed a y axis shift to the east is made shortly after lift off. This is why launch sites are as near as possible to the equator where the perceived rotational speed of the earth is at a maximum. Polar insertions launch directly south, there is also a y axis rotation, but for different reasons, and they lift smaller payloads for the same fuel expended as they cannot take advantage of the earth's rotation.
Hence (for example) the reasoning for positioning of the French rocket launch site and European spaceport to the northwest of Kourou in French Guiana!

While it is irrelevant, on the basis of the fact that the effect is negligible in the context of the rocket loads lifted, is is interesting to note that gravity is also less at the equator due to the greater distance between the earth's surface and the centre of the earth on account of the bulge there as a result of the greater rotational speed (angular momentum) as the the earth shape is that of an oblate spheroid.
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Re: Apollo 8 - Navigation musings

#25 Post by ian16th » Sun Feb 23, 2020 10:35 am

TheGreenGoblin wrote:
Sun Feb 23, 2020 9:18 am
While it is irrelevant, on the basis of the fact that the effect is negligible in the context of the rocket loads lifted, is is interesting to note that gravity is also less at the equator due to the greater distance between the earth's surface and the centre of the earth on account of the bulge there as a result of the greater rotational speed (angular momentum) as the the earth shape is that of an oblate spheroid.
So that's what caused my dizzy spells when I was on Gan!

I thought it was the duty free booze!
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Re: Apollo 8 - Navigation musings

#26 Post by TheGreenGoblin » Sun Feb 23, 2020 10:45 am

ian16th wrote:
Sun Feb 23, 2020 10:35 am
TheGreenGoblin wrote:
Sun Feb 23, 2020 9:18 am
While it is irrelevant, on the basis of the fact that the effect is negligible in the context of the rocket loads lifted, is is interesting to note that gravity is also less at the equator due to the greater distance between the earth's surface and the centre of the earth on account of the bulge there as a result of the greater rotational speed (angular momentum) as the the earth shape is that of an oblate spheroid.
So that's what caused my dizzy spells when I was on Gan!

I thought it was the duty free booze!
:YMPARTY: :YMPARTY: :YMPARTY:

You should also age faster at the equator in relation to a person at higher latitudes due to the special relativistic effects due to the lower gravity (arising from the rotational bulge) but due to the time dilation effect resulting from the higher rotational speed of the earth as a result of the earth's bulge there, this effect is neatly cancelled out. One extra nano second gained to have another drink might have been good! :)

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Re: Apollo 8 - Navigation musings

#27 Post by sidevalve » Fri Feb 28, 2020 5:30 pm

Another larger-than-life former astronaut - mentioned in "Riding Rockets" is 'Hoot' Gibson (F-14s)..

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Re: Apollo 8 - Navigation musings

#28 Post by TheGreenGoblin » Fri Feb 28, 2020 6:15 pm

sidevalve wrote:
Fri Feb 28, 2020 5:30 pm
- mentioned in "Riding Rockets" is 'Hoot' Gibson (F-14s)..
Flew as a pilot for Southwest airlines until he was forced to retire at 60!

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