### Dynamic Density Airship Concept

This is an airship I designed for the UAVForge competition, it takes advantage of its ability to alter its volume (and thus its density) to take off and land. It is 6 ft long, however folds down into a rucksack.

Some interesting technology I am looking at in terms of software is the Surface From Motion 3D environment estimation

http://ai.stanford.edu/~asaxena/reconstruction3d/

http://phototour.cs.washington.edu/bundler/

and Active Noise Control

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

Unfortunately I won't be able to enter into the UAVForge competition as I am travelling while their live video milestone is due, but I thought I would post it here anyway if anyone was interested.

• The wings are simply fold away, they don't represent the amount of buoyant force displaced. If you look closely (although I'll admit the video doesn't display this as well as it could have) the envelope itself is changing shape by being pulled in. Once the internal motor pulls it in it uses a locking system (similar to a fishing reel) to hold the envelope in its pressurised shape, so it doesn't be running unless its compressing the envelope, if its expanding or compressed no energy is used.

• Hmm, you do realize that without a place to put the displaced air, your motors will have to be continuously running, and the amount of change in buoyancy will probably be as much as much force that your motors can put out, which is relatively small.

Maybe you can use the folding system, but like Mike said have a compressor and tank/bladder hold the compressed helium.  Then you will not need a continuously running motor to keep the wings folded.

• The volume alteration is done by changing the shape of the envelope using nylon string and some internal motors. The envelope material is currently mylar and polyurethane combined together, but I might strengthen that with further testing.

• When the race to balloon across the Atlantic was at its peak some years ago my friend was running the physics for an attempt using a balloon with a similar idea. The balloon density was altered with an inner balloon which was inflated or deflated as necessary. A far more elegant solution but unfortunately they didn't have the money to work as fast as others....

• How did you plan to do the volume alteration feat? Air compression?