The last King of the Hill had Hank building his own coffin. So I was thinking about what mine would be like. One thing I thought would be cool would be to have a bladder filled with Helium to make it lighter for the pall bearers to carry. And I was also thinking that if I could put a remote control valve on it it could float down into the grave on it’s own with out the straps. So short story long, how would I figure out how much Helium I need?
A lot more than you could fit in the coffin. Some guy several years back went for a flight by attaching a lot of helium balloons to his lawn chair, and it took a lot more than you could fit in a coffin.
Bouyant force (is that the correct term?) is equal to the weight of whatever you’ve displaced. So the force generated by a helium baloon is equal to the weight of air the baloon displaces minus the weight of the helium itself. The baloon adds weight too, of course. I think you’re going to need a pretty large baloon…
If you’re being buried in a stripped out, empty, airtight, 5 mil thick skinned, double wide house trailer you shouldn’t have any trouble at all. Sadly, the backhoe rental to dig the pit will cost more than the helium.
You’re going to need a lot of helium.
From http://www.chemicool.com/, I obtained the following information:
Densities of gases at 20 degrees C (in grams/cubic centimeter)
Helium (He): 0.0001787
Nitrogen (N2): 0.0012506
Oxygen (O2): 0.001429
Assuming air is a mixture of 79% nitrogen and 21% oxygen, the estimated density of air can be considered to be 0.001288 g/cm3.
The buoyant force of one cm3 of helium would be (density of air) - (density of helium), or 0.001109 g/cm3.
Using my body mass as an example (~80 kg), one would need approximately 72 cubic meters of helium to make me “float.” Further, this amount of helium would not take into account the consequences of the mass of any vessel that would be required in order to contain such a quantity of helium. If we assume that the container would be a massless, spherical balloon, that ballon would need to have a diameter of 5.16 meters.
5.16m looks pretty large to me (~17’). Call your corner funeral house, perhaps they plan a Chistmas sale on hot air baloons.