# Practicality of lighter-than-air aircraft for temporary agricultural irrigation?

I'm building a colony that is an unintended eclectic museum of simultaneous, anachronistic stages of industry: Industrial, Machine Age, and Atomic+ (onward into more esoteric, advanced technologies that are strictly regulated for the sake of social experimentation).

Prior to the construction of a pipeline, road, or rail networks and other transportation, I intend for zeppelins to be used to travel between coastal desalination plants and back to the main city. In addition to delivering drinking water, they would dump some of their water while passing over designated farmland to irrigate the crops, and if needed, also transport and dispense necessary fertilizers, insecticide, etc.

I guess some would also stop at isolated plantations/farms to gather produce and deliver packages or necessary supplies for farmers and agricultural laborers.

This is only intended as a temporary solution until proper transportation and irrigation infrastructure is built...so I can explain the existence of a retrofit fleet of zeppelins being weaponized later...

Edit: Alright, probably unmodified, antiquated zeppelin designs are a miserable idea. Perhaps just magnetoships that use bags of lighter-than-air gasses to stabilize them, and appear aesthetically like antiquated zeppelins? Ach...But then what are all the problems with magnetoships that I don't know about? Or rather: What's a good freight vehicle that can float in the sky like a zeppelin?

And now I'm intending a scenario or circumstance in which there is an obstacle that prevents the simultaneous development of infrastructure alongside the construction of the coastal desalination plants:

"We need water. We need more of it than what's falling out of the sky. It's over there. There's something nasty/loathsome between here and there. So we went over it." It can maybe be a lake/river and its respective filtration/purification plant, since people keep yelling at me that desalination is a dumb idea.

Untamed wilderness...Voracious indigenous organisms...Obstinate xeno-druid roadblocks...What would stop a bunch of salty blue-collar humans in high-vis vests and hard hats? A lot of things I'm sure, but enough that it just makes sense to fly over it in the meantime...instead of say, call in someone to fight it (due to anticipated, constant harassment or guerrilla tactics).

Ugh, but now I've forgotten about the farms I wanted to irrigate with fly-by's...

Edit: Consensus is that fly-by irrigation is impractical, but could I perhaps just have water stored as freight and offloaded at designated stops (plantations/farms) via a simple tower of pipes sticking up in the air, probably connected to a water tower or something? A stable docking procedure is probably required.

Requested Details:

• Planet is artificially constructed and terraformed (by a much more advanced faction distinct and separate from the colonists that the narrative is concerned with)
• The conditions were intended to be very close to Earth-like but there are locations where it is obvious that the landscape is artificially sculpted on a massive scale...again, perhaps for the purpose of messing with/experimenting upon developing societies
• in this universe/reality, magic (of many different kinds) is known about, it exists, it is an oddity and impractical because of its known inconsistency over the scope of different celestial bodies ("My fireball spell summons dancing meat-cubes on this planet ._."). People try not to use it and stay away from it as much as possible...and it is considered distinct from occult and psychic shenanigans that are actually, and ironically, better understood and regulated...
• In my intended context, an overarching "social/technological experiment" imposed on the colony is that antiquated technologies are known about, but not understood in-depth. Possibly, they require reverse-engineering from memory or nothing at all? The intention was to motivate the development of alternative technologies: "Building things differently," Or hopefully, better than they functioned as we knew them.
• This is important for the anachronistic stratification of technology levels I mentioned first: Basically, there was a colony drop, the core of the ship is space-age tech, but only so much, and the people in charge of it shoo'd off the colonists, encouraging them to build around it with provided tools and materials from late Industrial Age tech and onward...because it was arbitrarily decided that that's when the curve of technological growth starts to get "interesting" ...I would word that more elegantly later in the terms of aforementioned sociological and technological experimentation of course...
• Please don't change the question after posting it. I spent some time writing up a well-researched answer, only to find that the question is different now. I recommend you roll back the edit and let the question stand as it was. If you have follow up questions, please post them separately. – kingledion Aug 15 '18 at 4:28
• Why on whatever_your_planet's_name_is would you use desalinization plants period, let alone to irrigate crops? Put your colony where there's plenty of natural rainfall. Re irrigating via Zepplin, one acre-foot of water (you'll need several for most crops) weighs about 1300 tons. A Zeppelin's lifting capacity is about 16 tons. Do the math :-) – jamesqf Aug 15 '18 at 4:30
• Sorry, I was responding to the first answer as you were probably writing. I thought it made sense to continue with adjustments somewhere else, but the UI told me to just throw it into an edit on the original post. I am now confused. I finally made an account on this site only hours ago. – Lawd Mawdjulus Aug 15 '18 at 4:31
• @jamesqf where the heck do you have these numbers from? The lifting capacity is super wrong – dot_Sp0T Aug 15 '18 at 4:33
• @dot_Sp0T: From here: en.wikipedia.org/wiki/LZ_127_Graf_Zeppelin I quote "The Graf Zeppelin had a total lift capacity of 87,000 kg (192,000 lb) with a usable payload of 15,000 kg (33,000 lb)..." If you disagree, take it up with the authors of the Wikipedia page :-) Even modern proposals like the Airlander smithsonianmag.com/innovation/… or LMH-1 only have a 25-50 ton capacity. – jamesqf Aug 15 '18 at 18:05

# Not feasible

Your planet might not have the same atmospheric conditions as Earth, or you may have some magical elements available to fill a zeppelin's lift envelope; you don't specify. But assuming Earth-like conditions and Earth-like zeppelins, irrigation by zeppelin is very impractical.

The famous (for burning) Hindenburg had the largest envelope volume of any airship. It generated about 216,000 kg of lift (I know, the units are wacky) and had a mass of ~206,000 kg. So, it could only carry about 5 tons of payload, including passengers and what have you. By comparison, a Boeing 777 can lift over 50 tons, depending on the model.

Fertilizer is heavy; water is even heavier. A corn field in Illinois might use 150 lb of nitrogen fertilizer per acre for a season. A farmer's bulletin recommends a similar amount of potassium (137 lb) and phosphorous (134) addition. These fields also average 191 million gallons per day for 601,000 acres of irrigated crops. That is just over a ton of water per acre, per day.

One zeppelin trip fully loaded can carry enough fertilizer for about 22 acres, per season. It can carry enough water for 2 acres for a day.

You're going to need a lot of zeppelins, at modern farming fertilizer and irrigation usage rates.

• Your numbers are utterly off.. wherever you got these valuesfrom you/they did forget that most of the payload-capacity on the hindenburg was used up for things such as: the accomodations (crew/passenger quarters, restaurants, view decks, a piano, etc pp). In a scenario where you colonize another planet you can strip most of that stuff out and reduce it to the weight of the envelope + superstructre, and any fuel necessary for the engines (+ ballast, but we didn't strip that) – dot_Sp0T Aug 15 '18 at 4:42
• @dot_Sp0T Its broken down in the link. Hindenburg has almost 50 tons of lift, but half of that is eaten by fuel; then there is ballast, weight of the crew, provisions for the crew, etc. Sure you could optimize an airship for more like 50 tons of lift, but that isn't clear from the tech level given by the OP, and a factor of 10 (or even 100) doesn't make the zeppelin much more useful for irrigation. – kingledion Aug 15 '18 at 4:46
• @kingledion now we're running into an issue here. The [newest zeppelin](en.m.wikipedia.org/wiki/Deutsche_Zeppelin_Reederei) having been built is only 15 years old today. Having been put into commission in 2003 - or is that not a zeppelin? It's a zeppelin by all rights and definitions of zeppelin though. If we start assuming that the OP didn't even mean zeppelins but airships in general, which is a very approachable thought given the data in the qeustion (still being added apparently), we could probably even start thinking about using these: – dot_Sp0T Aug 15 '18 at 5:19
• @kingledion also 'von Hindenburg' would actually be the person the airship was named after. For about 3 years both of them existed in parallel, then von Hindenburg died. – dot_Sp0T Aug 15 '18 at 6:15
• @dot_Sp0T Ouch, still slamming me... – kingledion Aug 15 '18 at 18:33

The only way I see a Zeppelin working is if it's extremely hard to get to the colony on foot and you have enough resources to warrant the building of the colony and open up new paths.

For example, let's say you have two Cities on opposite sides of a huge mountain range. There are paths between each city, but they have to go around the mountain range (and assuming the straight line distance through the mountain range will still take more than a day via your main form of transportation). The paths are so long that zeppelins are viable in transporting cargo over the mountains (They transport less, but get there quicker and more reliably(?)).

Now both cities could invest in building a path between the two of them through the mountain range. Assuming there was an almost ideal settlement area in the mountains, then your scenario might work. The cities start mining from each of there sides. They use the zeppelins to move supplies, materials and manpower into the mountain range to start construction work before the main crew gets there. Assuming a suitable location about half a days away, they start the construction of a city, using zeppelins to supply materials and manpower while proper transportation lines are being constructed.

Something like this? maybe

• ...ooooo what if the farms were on plots of land cut out of the side of mountains? That'd seem annoying to build roads to each one, and more convenient to spray while flying by...Or is that an entirely different and problematic issue? – Lawd Mawdjulus Aug 15 '18 at 5:33
• I think its going to depend on what crop they are growing. If it was like rice, i could imagine the water overflowing and supplying the other paddies as well. But if you wanted wheat or corn i dont think it would work. You could also have the city developed to look appeasing to the eye rather than practicality which gives you a lot of flexibility in the design. – Shadowzee Aug 15 '18 at 5:40

In addition to the issues of lift and payload capacity, Zeppelins and other LTA craft are essentially giant sails, and have great difficulty in flying in high winds or heavy weather conditions. This led to the crashes of many airships.

From a practical point of view, the act of using an airship as an irrigation system would involve some pretty difficult flying, since you want to place the water "on target". The airship is moving slowly over the field, but the pilot needs to account for shifting winds, changing weight (the airship will become lighter as the water is delivered, and want to rise, while the pilot will want to remain relatively low to the ground).

Utilization will also be horrible. Turning about at the end of the field will take a long time, then trying to line up and fly the next section of the field will also take a very long time. You will spend an inordinate amount of time trying to water just one field. Even watering the field with a cropduster would make more sense in terms of time allocated.

Air delivery of water can take place, but using fixed wing aircraft like "water bombers", or helicopters to deliver water via bucket lift. If there were no other real alternative, the would be a very expensive way to irrigate a field.

• Simply as a practical matter, water bombers transport far less water than would be needed for irrigation. – jamesqf Aug 15 '18 at 19:59
• Which is why using aircraft to irrigate fields is non optimal for any platform. – Thucydides Aug 16 '18 at 1:10
• And yet another problem: if you're irrigating these fields, the air is presumably hot and dry, therefore unless you fly really low, much of your payload evaporates before it reaches the ground. See virga: en.wikipedia.org/wiki/Virga – jamesqf Aug 17 '18 at 14:23

Practically, Zeppelins are a pain. Even the ones filled with helium have all crashed in bad (and by "bad", I mean "high winds") weather.

Just build the roads and ditches at the same time you're building the desalination plants (which themselves need a lot of energy, so you'll have to have that infrastructure built before the desalination plants come online, and you'll need roads to build power stations).

•  Even the ones filled with helium have all crashed in bad (and by "bad", I mean "high winds") weather. They also sink at night. <- citation needed – dot_Sp0T Aug 15 '18 at 4:36
• @dot_Sp0T en.wikipedia.org/wiki/Fu-Go_balloon_bomb/Origins "A hydrogen balloon expands when warmed by the sunlight, and rises; then it contracts when cooled at night, and falls. The engineers devised a control system driven by an altimeter to discard ballast. When the balloon descended below 9 km (30,000 ft), it electrically fired a charge to cut loose sandbags. ... Similarly, when the balloon rose above about 11.6 km (38,000 ft), the altimeter activated a valve to vent hydrogen." – RonJohn Aug 15 '18 at 5:36
• That's not a zeppelin envelope, that's a balloon-bomb; not the same thing by a wide margin – dot_Sp0T Aug 15 '18 at 5:38
• @dot_Sp0T they're both lighter-than-air vessels. – RonJohn Aug 15 '18 at 5:40
• The Wollfia and the Pumpkin are both vegetables, yet you wouldn't use the nutritional values of one of them as a substitute for those of the other? Or carve a Jack-O-Lantern from a Wollfia pod? Or really do any comparisons other than this one showing that your argument holds no weight (got it, lighter-than-air-pun) – dot_Sp0T Aug 15 '18 at 5:44