End correction?

R7ll

I missed a lesson at school on end correction of standing waves in pipes. I have a vague understanding of them, but can anyone give me an idiot's guide to end correction? Most websites i've had a look at haven't been too helpful in explaining it.

Now, this is just a guess, but am I right to assume that if i detected a fundamental in a tube with one end open and one end closed, the wavelength of that wave is not four times the length of the tube, but actually four times the length of the tube, and four times the end correction added on top of that?
I also read somewhere that the end correction distance is something like 0.61 * r where r is the radius of the tube... is this correct
Thanks