[Open Rocket] What are the Acceleration Units for G?

[Mark Phillips]

In the preferences menu, one can choose either meters/sec/sec, ft/sec/sec, or G for the acceleration units. I assume G stands for "g", the acceleration of gravity, and not G, the universal gravitational constant. However, g, the acceleration of gravity, is measured in some units - ft/sec/sec, meters/sec/sec, furlongs/fortnight/fortnight, etc. So, if I pick G, what are the units?

I did some experimentation with simulating a design, and it seems that the units of G default to SI when velocity is SI, and English when velocity is English. Can someone verify if that is true? If it is not true, what are the units of G?

Also, I would suggest that G be changed to g, as G is an incorrect symbol for the acceleration due to gravity.

Thanks,

Mark

 

[CarVac]

g is g is g:
g = 32.17 ft/s^2 = 9.806 m/s^2. The value for g that your rocket achieves will stay identical as long as your rocket performs identically in the simulations.

If you want to be nitpicky, it should be g_0: https://en.wikipedia.org/wiki/Standard_gravity

 

[Sampo]

Hi,

I recall thinking about the unit for quite some while, and deciding on the capital G since 'g' is the unit for gram. g_0 might be a reasonable alternative, but I don't really see much need to change it.

Cheers,
Sampo N.

 

[UhClem]

It is really very simple: G is a unitless number. (aka a dimensionless number)

To calculate acceleration in G's you divide your acceleration by the acceleration due to gravity. Both of those values do have to be in the same units. (ft/sec/sec, m/sec/sec, furlongs/fortnight/fortnight, whatever you prefer.) When you do that division, the units cancel and the result has no units. Just like the Reynolds number and countless other unitless numbers.