Airlocks

I have a couple of ideas on how airlocks might be improved. Both would remove more air more quickly than any current airlocks. Of course the only airlock we have right now is on the Space Shuttle, so the comparison is a bit unfair. They would add some complexity and mass, so the only place they would be useful would be where the air and time they saved would be worth the cost of boosting the extra material into space. Being as the cost of boosting the material is currently a couple of orders of magnitude greater than the cost of the material, we can neglect the cost of actually building these devices. The first device would use large plastic bags to force the air in the chamber out. The collapsed bags would line two opposing walls of a airlock. Inflated with air, they would meet in the middle and completely fill the chamber. To operate, a space suited person would stand in the middle of the chamber facing one of the bag lined walls with arms and legs spread. Evacuation of the chamber would begin. The bags would be inflated with perhaps double the current atmospheric pressure. This will encourage the air in the chamber to leave. When a satisfactory amount of air had been evacuated from the chamber, the pressure in the bags would be relieved, and the bags would drawn back to the walls by the means of straps attached to the insides and/or outsides of the bags. The bags would need to be made of a tough material to withstand the pressures involved. The tougher the bags, the higher the pressures could be and the quicker the airlock could be cycled. We would want to be careful not to exert too much pressure on the person in the lock, we would not want any crushing injuries. It would be nice if the bag could be made of a transparent material to alleviate any feelings of claustrophobia. The second device is simply a large diameter, long cylinder attached to the airlock. The cylinder would have about ten times the volume of the airlock. When the people entered the airlock, a piston in the cylinder would be next to the chamber. The other side of the piston would be vacuum. When the airlock was sealed, the piston would be released. The air in the chamber would expand and push the piston to the far end of the cylinder. The opening between the airlock and the cylinder would be sealed and the airlock could be opened to space. We would lose perhaps ten percent of the air with each cycle, but it would be very quick, a matter of seconds at most.