Originally Posted by
Skygirl
Thanks Tom! I appreciate your answer and wisdom. Did I hear somewhere that in the newer aircraft that they were putting in more advanced air filtration systems that had a greater intake of fresh outside air? I realize that there is no getting around the dry air problem at altitude, unless someone can come up with some sort of efficient humidifying system. Now that could make an enterprising engineer a multimillionaire!
The 787 will have electric pneumatic pumps for pressurization instead of using engine bleed air. On older airplanes cabin air is/was recirculated to save fuel (takes fuel to produce engine bleed air).
Because this plane has PLENTY of electrical generating capacity without significantly impacting fuel burn - it would reason that cabin air turnover wouldn't be the issue it was. I don't know what the air turn over rate will be on the 787, but based on the systems I'd guess it would be improved over the 777. The 787 will also have HEPA filters but I don't believe that the filtration affects cabin airflow rates.
The dry air problem is more of a challenge. Simply stated: it takes water to make humidity, water has weight, it takes fuel to carry weight. The engineer that can find a solution to the "gravity problem" would indeed do quite well.