(This posting was followed up in a more analytical way here.)
Here’s a blimp that can put down a payload in a remote place.
This is actually a big deal. A conventional blimp can carry a heavy load much more fuel-efficiently than an airplane or helicopter, sure, but can’t put it down!
When the weight of the payload is lost, a regular blimp suddenly has too much lift and can’t land! Dangit!
The only two (believable) solutions to this problem so far even suggested, as far as I know, are to either 1) Just release some expensive lifting gas into the atmosphere, or 2) Trade the payload for something equally heavy like water pumped up from waiting tanker trucks.
Both solutions #1 and #2 above stink.
#1, venting lifting gas, stinks because lifting gas (helium or hydrogen) isn’t cheap. If I want to put down a nine-pound gallon of diesel fuel at a diamond mine in northern Canada, but also have to vent four or five dollars’ worth of lifting gas in the process, then that diesel just got really expensive!
#2, trading the payload for water pumped up from below, sucks because not only must there be water trucks handy, but they must be able to get to the drop site. If a truck can get there then what’s the blimp for?
So! Here’s my solution #3:
Right before dropping its payload, the blimp deploys these hanging parafoils (like the wings of paragliders, but hanging upside-down) and gooses the engines to start moving through the air. The hanging parafoils generate aerodynamic down-force (like aerodynamic lift but in the downward direction) to compensate for the payload’s lost weight!
The key complication to this scheme, then, is that in order to be able to stop again — which has to happen eventually, namely back at the logistics base where the mission started — the blimp needs to lose lift and/or gain weight, so that the parafols won’t be needed anymore and can be winched back up against the blimp’s envelope.
Lift can be lost in a productive way by having all or some of the lifting gas be CH4, aka methane, aka natural gas, and just burning it up as fuel (‘cuz ‘gotta burn something, and CH4, if it’s available, is always cheaper than diesel fuel anyway). Further, water vapor in the engines’ exhaust can be condensed to liquid water and retained in tanks, thus doubling the lift-losing/weight-gaining effect.
(The same scheme works if the lifting gas being burned up as fuel is just hydrogen. You just need the extra machinery at the base to make that hydrogen gas in the first place plus engines that can burn it safely, a perfectly doable but not-so-off-the-shelf sort of thing. What’s nice about hydrogen, though, is that not only does it lift twice as much as CH4 per volume, but gives about a quarter as much fuel energy per volume too. Ergo, burning hydrogen gas instead of CH4 lets us lose-lift/gain-weight about 4X as quickly!)
Another way to gain weight is to fly over a body of water at any point along the way back and scoop up water through a special boom. Here’s a video demo of a helicopter doing this.
And there we have it: A blimp (with some physical and procedural complexities stapled on) that actually can put something down in a remote place in a controlled, cost-efficient and non-catastrophic way! This could be a big deal in the oil/gas exploration, military logistics and/or emergency humanitarian aid businesses (and/or the other fields that you can help me brainstorm here).
A final interesting tidbit is that since it’s so advantageous to be able to scoop up water on the way back to base, it’s an interesting idea to have that base be a ship. That’s pretty interesting, becauase now you’re doing heavy deliveries in-country directly from a ship, without having to deal with the roadblocks, washouts, mudslides, theft, spoilage or bribe-seeking customs goons on land! Awesome!
