# Vacuum Lift

## Main Question or Discussion Point

I'm working on a project with several others to create a flying device much like a blimp, but smaller and more agile. Our method of life is eighther a light gas like helium or preferablly, a Vacuum system that ajusts the % of vacuum inside a set space to provide lift and control decent. The system itself has been planned and construction has began, but for our computer guidance sytem I need to know exactlly how much lift a Square foot of Vacuum can provide so we don't end up crahing. Does anyone know the figure or the equation to find it. I've seached, but have always been directed to scuba sites. Please help.

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mgb_phys
Homework Helper
A square foot of vacuum doesn't give you any lift.
A cubic foot of vacuum will give lift eault to the weight of a cubic foot of air, 1m^3 of air is around 1.3kg.

Good luck designing a lightweight structure that can support itself against the air pressure.

Thank-you, We've created a titanium orb with an intricate interior support structure that has proven strong enough to withstand 28 psi for up to 10 hours at total vacuum. There will be four of these orbs suspending a cockpit. Unfortunately our guidance system will have to be redesigned becasue I incorrectly programmed it to accept operate on one constant lifting capacity. I now realize my bluster. This mistake will set us back months, but that's my fault thanks for your help.

We've created a titanium orb with an intricate interior support structure that has proven strong enough to withstand 28 psi for up to 10 hours at total vacuum.
I bet your orbs (with support structures) are heavier than air. As far as I know, nobody has ever built lighter-than-air structures that can withstand atmospheric pressure and do not contain any lighter-than-air gases. I am not saying it is impossible, but it's really difficult.

DaveC426913
Gold Member
A cubic metre of air weighs about 1.2 kg.

If your orbs contained a cubic metre of vacuum, their entire structure would have to weight less than 1.2kg in order for them to be bouyant.

To lift a 70kg man, and (we'll say, optimistically) 30kg of structure, your 4 orbs will have to enclose 83m^3 of vacuum, making them each about 3m in diameter.

You orbs will have to each weigh about 5kg, be 3m in diameter and still withstand 10 tons of pressure per square metre.