I've tried to collect some more boring, but nevertheless necessary formulae. This also elevates the 'science level' behind the project (makes it look more important!).
For example, it's not too practical if you just estimate the size of the parachute, and it's so slow that it travels 100km farther than estimated! (Remember, it's falling from 30km height)
On this page, I've put all formulas necessary to convert between pressure, humidity and temperature - important if you want to use a pressure gauge to measure height.
For those who find formulas boring, here's an on-line calculator that permits you to input a few parameters, and calculate the missing ones. While it's not for in-flight use, but it is quite practical to have around, even just for few test. Do you know the pressure at 30km?
Another common problem is estimating the descent speed, taking into account parachute diameter, and payload weight. It's important to find a compomise between fall speed, and distance the payload travels during the fall. Remember, winds are more than 100km/h on the way down.
New! To make it even easier to calculate parachute diameter, i've added a slide calculator (who remembers this?). With this thing, it's easy to estimate the diameter necessary to obtain a certain speed (or time).
|(c) John Coppens ON6JC/LW3HAZ|