Gs to Speed Converstion

I am looking for the math equation that converts G load to speed using Arduino (https://www.adafruit.com/products/2796)?  I am building a high power rocket data logger/controller. I need to know the speed by using accelerate of the bird. Yes I might be able to use GPS info, but at super sonic speed GPS can not keep track of the speed. The bird is a 2 stage bird. I want to stage when about 40% of the speed has bleed off. 


Rocket Nut

sort by: active | newest | oldest
Kiteman4 days ago

Assuming constant acceleration and straight-line flight...

v = u+at

Final velocity = initial velocity + (acceleration*time)

Initial velocity = zero, so...

v = at

"a" = acceleration in m/s/s

1g = 9.81m/s/s

So, v = (number of Gs) * 9.81 * (time of flight in seconds)



Rocket Nut (author)  Kiteman4 days ago
Thanks I think that will work.

It better, or my students are in deep trouble... LOL

Rocket Nut (author)  Kiteman4 days ago

I was looking over your equation, I might see a problem tho. What happens when the booster burns out and the G load drops to zero, then the "v" drops to zero (v = 0 * 9.81 * (time of flight in seconds). So how do I know when the 40% speed reduction has been activated, and fire next stage?

That's why I said "assuming constant acceleration"!

I've asked somebody with more rocketry knowledge than me to have a look - we'll see if he's able when time zones catch up.

Rocket Nut (author)  Rocket Nut4 days ago

May be I should mention what Accelorometer I plan to use. It's from Adafruit (https://www.adafruit.com/products/1231).