# Lighter than air frame

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1. Nov 20, 2014

### Rooler

Can you use a vacuum, or lighter than air gas within a tubular frame network to neutralize the apparent weight of the frame? If this is possible what is thee smallest possible size you could make this frame, I understand that the more you scale it up the lighter proportionately the frame would become therefore finding the smallest possible size and working up into more useful sizes is the most logical and economical idea.

2. Nov 20, 2014

### Staff: Mentor

Welcome to Physics Forums!

A fellow named Zeppelin carried out your idea beginning about a hundred years ago, using a lighter-than-air gas: hydrogen, which ended up having disastrous consequences. Helium is safer but scarcer and much more expensive. A company in Germany is developing a semi-rigid airship which apparently does not try to cancel the weight of the frame completely:

http://en.wikipedia.org/wiki/Zeppelin_NT

I expect using a vacuum would be impractical because of the stresses that the external air pressure would produce on the frame.

Last edited: Nov 20, 2014
3. Nov 20, 2014

### Bystander

You know the density of air; you can look up the density of materials from which you might wish to fabricate your framework; you can calculate a minimum wall thickness to resist atmospheric pressure (for vacuum), or to support your structure and loads; from wall thickness you calculate mass.

4. Nov 20, 2014

### Rooler

I knew about Zepplins design my idea is to use a lighter than air frame work to build a semi rigid envelope to house a lighter than air gas, the idea would be to increase the amount of cargo mass- envelope size

5. Nov 20, 2014

### Rooler

My question came from an idea to set up salt water mining or salt refining plants on a coast line in an arid region of the world, concentrate the brine using electrolysis, releasing or harvesting the split O2 and filling airships with excess hydrogen "having collapsible envelopes for the return trip to allow larger amounts of cargo to be moved" to move cargoes of compressed hydrogen inland to be burned in power plants also producing clean water.