What is the formula for gravity loss on a rocket launch and how was it derived?

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  • Thread starter Thread starter Januz Johansen
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    Gravity Loss Rocket
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Discussion Overview

The discussion revolves around the formula for gravity loss during a rocket launch, exploring its derivation and the factors influencing it, particularly the flight path angle. The scope includes theoretical aspects of rocket dynamics and gravitational effects on motion.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant seeks clarification on the formula for gravity loss, specifically its dependence on gravitational acceleration and flight path angle.
  • Another participant explains that gravity loss is related to the component of gravitational force acting along the rocket's velocity, integrated over the flight time.
  • A follow-up question addresses the necessity of considering the flight path angle in the context of gravity loss.
  • It is noted that acceleration orthogonal to the direction of motion does not affect the speed of the rocket.

Areas of Agreement / Disagreement

Participants express different aspects of the gravity loss concept, but there is no consensus on the necessity of the flight path angle or the implications of orthogonal acceleration. The discussion remains unresolved regarding the derivation and full understanding of the formula.

Contextual Notes

The discussion does not clarify the specific assumptions underlying the formula or the mathematical steps involved in its derivation. The role of the flight path angle in the context of gravity loss is also not fully resolved.

Januz Johansen
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Hello all!
Lately i have been looking at many rocket equations, and i was wondering about the gravity loss on a rocket launch. I found the formula for the gravity loss
upload_2016-12-2_21-16-52.png

where g is of course the gravitational acceleration, and y is the flight path angle, but can someone explane why it looks like this? How has this been deduced?
Thanks
 
Last edited by a moderator:
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It is the component of the gravitational force along the velocity of the rocket (=the component changing the velocity), integrated over the whole rocket flight time.
 
mfb said:
It is the component of the gravitational force along the velocity of the rocket (=the component changing the velocity), integrated over the whole rocket flight time.

Okay thanks
But why do we have to take the Angle into accound?
 
Acceleration orthogonal to the direction of motion does not change the speed.
 
mfb said:
Acceleration orthogonal to the direction of motion does not change the speed.
Okay thank you
 

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