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Hey Chuck, I actually replied to your comment on the "Human-Powered Helicopter Wins the $250,000 Sikorsky Prize" thread about a more conventional way we could a

Hey Chuck, I actually replied to your comment on the "Human-Powered Helicopter Wins the $250,000 Sikorsky Prize" thread about a more conventional way we could achieve "permanent points of presence in the air" before we enter the "Diamond Age" :) - and I was curious about your thoughts on it, given that I'm not anything close to an engineer. Anyway, sorry to bug you, just curious if there's anything to it. ========= I've often wondered if a balloon-based system might be the way that this ("permanent" points of presence in the air) is eventually achieved. As solar energy becomes more and more efficient every year (apparently it's on an exponential price/performance growth curve), you coat the balloon with a light-weight, flexible solar array, and either heat the air like a hot air balloon, or as it becomes cheaper and more efficient to extract hydrogen from water, fill the balloon with hydrogen, and constantly replace the hydrogen that leaks out with hydrogen extracted from water vapor in the air: http://www.technologyreview.com/view/512996/a-cheaper-way-to.. http://www.technologyreview.com/view/512996/a-cheaper-way-to.... You could use low powered propellers (like a blimp), and take advantage of weather patterns (like Google's Loon project) in order to maintain position or to slowly travel.

ChuckMcM 13y ago
The general challenge with balloons is drag, or specifically their response (or lack thereof) in the presence of winds so staying in one place can be problematic. I like the idea of cracking water to get hydrogen to replenish your lift bags, but if you are to fly this over the flyways (say at 60,000') you're not going to get a lot of moisture in the air. The old Zeppelins had gas generators which, while they had to be replenished, could supply plenty of hydrogen during the journey. Google's balloon system [1] is apparently using quantity to cover holes that appear when winds blow them down range. Also if they get caught in the jet stream the can leave the area in a hurry. Granted winds are a challenge for any aerial platform but actively flying shapes, seem to out perform lighter than air ideas when staying on station is required [2]. So solving the station keeping question would be a big part of the equation. That said, the company that proposed the blimp to the Army is continuing to develop it as far as I can tell from their web site [3]. Perhaps it will get additional engineering work on those issues. [1] http://www.google.com/loon/#utm_source=google&utm_medium=cpc&utm_campaign=Global_semBK http://www.google.com/loon/#utm_source=google&utm_medium=cpc... [2] http://www.popsci.com/technology/article/2013-02/army-cancels-airship http://www.popsci.com/technology/article/2013-02/army-cancel... [3] http://airshipmanufacturing.com/sentinel-2-airship.html http://airshipmanufacturing.com/sentinel-2-airship.html

ChuckMcM 13y ago

The general challenge with balloons is drag, or specifically their response (or lack thereof) in the presence of winds so staying in one place can be problematic. I like the idea of cracking water to get hydrogen to replenish your lift bags, but if you are to fly this over the flyways (say at 60,000') you're not going to get a lot of moisture in the air. The old Zeppelins had gas generators which, while they had to be replenished, could supply plenty of hydrogen during the journey. Google's balloon system [1] is apparently using quantity to cover holes that appear when winds blow them down range. Also if they get caught in the jet stream the can leave the area in a hurry. Granted winds are a challenge for any aerial platform but actively flying shapes, seem to out perform lighter than air ideas when staying on station is required [2]. So solving the station keeping question would be a big part of the equation. That said, the company that proposed the blimp to the Army is continuing to develop it as far as I can tell from their web site [3]. Perhaps it will get additional engineering work on those issues. [1] http://www.google.com/loon/#utm_source=google&utm_medium=cpc&utm_campaign=Global_semBK http://www.google.com/loon/#utm_source=google&utm_medium=cpc... [2] http://www.popsci.com/technology/article/2013-02/army-cancels-airship http://www.popsci.com/technology/article/2013-02/army-cancel... [3] http://airshipmanufacturing.com/sentinel-2-airship.html http://airshipmanufacturing.com/sentinel-2-airship.html