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Thread: Zeppelin design, real and fictitious

  1. #1
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    Zeppelin design, real and fictitious

    As mentioned in another post, I am writing up stuff for a Swedish roleplaying game that have Zeppelins in it. But before looking at things that are directly tied to game, I thought that I should think aloud a bit here and hopefully get some input from other that frequent this place

    I guess this could be used for a pre-warp world in Trek as well.

    What I am looking for is something that feels plausible to me even if looking at details. So it will have to be at least somewhat grounded in real world facts. Now, as I see the setting, it is a world where innovation is stifled, but improvements do happen even if it is slowly. So technology that is available during the 30s can be considered, and improvement of that technology can be considered up to the 50s or even the very early part of the 60s.

    Airplane technology I think I will have reached only about what flew around at the outbreak of the first World War.

    As it isn't limited to the real world, the real world availability of Helium does not have to be taken into account.

    A good site that I have found is http://www.airships.net/ which have quite a bit of information.

    As an example, some numbers about the Hindenburg can be found there; comparing hydrogen and helium (it was apparently originally designed for Helium).

    Code:
    				LZ-129 Hindenburg	kg	lbs
    		
    				Dead weight		118,000	260,145
    				Crew			5,400	11,905
    				Provisions		3,000	6,614
    				Fuel			58,880	129,808
    				Oil			4,000	8,818
    				Ballast			7,950	17,527
    				Misc.			9,120	20,106
    							206,350	454,924
    		
    Gross lift/hydrogen (68lbs/1,000 cu. ft.)		215,910	476,000
    Payload for passengers, mail, freight w/ hydrogen	9,560	21,076
    		
    		
    Gross lift/helium  (60lbs/1,000 cu. ft.)		190,509	420,000
    Payload for passengers, mail, freight w/ helium		-15,841	-34,924
    This example above have hydrogen being 13% more efficient than helium, and other sources have stated it being closer to 8%. I have also heard that Hindenburg had about 200,000 cubic meters of gas volume, and each cubic meter gives one kilo of lift. That would match that 8% difference.

    Now, I imagine Zeppelins being used for both civilian and military uses. Civilian uses would probably be quite close to how they where used in the mid-late 30s. Germany tried to use Zeppelin during WWI, but that appears to have been quite a failure.

    The current opinion seems to be that it was the paint of the Hindenburg that caught fire, and that fire ignited the hydrogen. So if the ship had been painted in a non, or at least less, flammable paint it might not have ended the way it did.

    The Zeppelin used to attack England during WWI apparently had a tendency to end up in flames. One tracer seems to have been enough to ignite the hydrogen. But one of the sites I have been looking at (not sure if it is on the above mentioned or another one) claimed a statistic that only 1 in 8000 rounds managed to hit a Zeppelin, and that a normal round is not enough to ignite hydrogen. Flying in over a well defended area like London means a lot of bullets.

    If the gas isn't ignited, it would just make the gas below that hole to leak out. Just as if it was filled with water, the gas would not disappear out of the hole immediately.

    In a Zeppelin, the gas is in several large balloons. So even if the top of one balloon is punctured, the ship will still not lose all if its lift.

    So if ship could be built with a lighter frame and more efficient engines, it would give quite a bit of extra payload. Segmenting the gas into more balloons, and having collector valves to recycle the gas, would cost weight but making the Zeppelin far less vulnerable and thus more suitable as a combat vessel.

    From a combat point of view, I sort of envision Zeppelins firing at each other with light or medium artillery guns and medium to heavy machineguns. By not having a particularly hard hull, a shell would probably not be able to detonate on impact and have to be set with a timer that start counting when fired. So most shells detonate to early or to late.

    So a good starting point is to look at how to shave of weight on the hull and balloons (better material and more efficient design), engines (better power/weight ratio and less fuel consumption); and roughly what a good gas collector system would require and weight (valves, pipes, etc).

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    How plausible is an armed Zeppelin?

    Just to see if there would be any plausibility in a Zeppelin based war ship, I will make some assumptions and grab some values from thin air.

    Assuming the dead weight can be lowered by 20% based on better material, better methods of constructing the hull, and lighter more efficient engines. The accommodation for a military vessel probably quite a bit less than a ship where a ticket was more expensive than a first class ticket for an ocean liner.

    The information above is based on a trans-atlantic flight from Rio de Janeiro to Freidrichhafen. A 12 hour mission over land require far less fuel, oil and provisions, so my take is that those can be cut with 90%.

    By not being a passenger ship, there is no need to have crew to tend to those passenger. There is also not the same need for multiple shifts at the bridge. Depending on if the controlling equipment has some form of hydraulic power steering, and trim rudders, to require less manual labor to control the ship; the number of crew can be lowered even more. So a rough estimate is that the crew weight can at least be cut in half (gun crews, etc not included).

    With the above mentioned assumptions, Misc. could probably at least be cut in half as well.

    The ballast do I assume to be able to be replaced with a supporting structure, a bomb bay, and perhaps two gun turrets mounted under the ship. So the same weight there, but replacing it with something useful. If it is a cargo ship, then the ballast might be possible to replace with structures for storing said cargo. This however is under the assumption that it is a static ballast to give it a clear down and minimize a tendency to roll. Dynamic ballast, as in pumping around a fluid between different tanks, to keep the ship balanced is another matter. Pumping fuel back and forth is for example used on some airplanes.

    I also toss in the assumption of helium being pure enough to get a lift of 200,000.

    Code:
    	Airship Type I		     kg	    lbs
    
    	Dead weight		 94,400	208,116
    	Crew			  2,700	  5,653
    	Provisions		    300	    661
    	Fuel			  5,888	 12,981
    	Oil			    400	    882
    	Ballast			  7,950	 17,527
    	Misc.			  4,560	 10,053
    				116,198	255,873
    		
    	Gross lift/helium	200,000	440,925
    	Payload			 83,802	185,052
    Now, the available payload will decrease on what altitudes and climates the ship is intended to operate in. System to recycle helium, and a lot of balloons/cells to make it less vulnerable to enemy fire, will eat into that payload. But it will definitely be enough lift available to haul a lot of cargo, troops, or make something that can take and give a bit of damage.

    Some plausible armaments would be something like Vickers machine guns, weighting in on about 15-23 kg each according to wikipedia. Having it mounted, a single crew man should be enough to manage it. The weight of each round would be about the same as a 7.62N; 24 grams. Assuming 100 kg for a crew man, 20 kg for the weapon, 100 kilo for a platform and port to fire from, and 120 kg for 5000 rounds of ammunition, gives 340 kg per machine gun.

    A 75mm M1916 gun weights in on around 340 kg. Accordingly to http://www.passioncompassion1418.com...munitions.html a French 75mm high-explosive shell weighted in at 5.3 kg, which I assume is the shell that the M1916 was built to handle. Now, those 5.3 kg is most likely the grenade only and not the propellant. So a guess on about 8 kg per round. Having a more sturdy platform of 200 kg, a two man crew, and 50 rounds of ammunition would weight in at 1140 kg per gun.

    10 guns per side, and 20 machine-guns spread out around the airship, and we have 30,000 kg. Still 53,000 kg for a main armament under the ship, survivability, and the option to operate on higher altitudes or long range operations.

    Quite some broad generalizations and assumptions, but sounds plausible enough for my taste

  3. #3
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    I've been a zeppelin buff for years. Always wanted to play an RPG with an airship, never had a chance to.

    For ballast, you might want to consider the method modern blimps use to trim their lift. They have ballonets, air-filled bags inside their envelopes, which can be inflated or deflated. Inflated ballonets have more weight and expand into the helium envelopes, compressing the helium and reducing lift. So, that basically means you can use air for ballast. You don't need to carry as much ballast when you can refill it from the air around you, but you'll still want some water ballast for emergency situations.

    I'd say your gun crews are undermanned. It was usual to assign at least two men to a Vickers gun, one to shoot and the other to keep the ammo coming and the cooling jacket working. Not sure about the standard crew size for a 75 mm, but I'm guessing more than two, especially if you're trying to maintain a high rate of fire.

    I like the idea of airships firing at each other with broadsides of time-fused shells. But if you're trying for realistic engineering, you'll need to account for recoil. Just guessing here, but I don't believe a zeppelin framework could absorb the recoil of a standard 75. Recoilless guns might work, if you made sure the backblast was directed away from the hull. Maybe put the guns in open swivel mounts on the top and bottom of the centerline.

    Another recoilless possibility is rockets. The Russian Katyusha of WW2 was effective and low tech. A few French WW1 fighter planes mounted rockets on their wing struts. Those were somewhat effective against German observation balloons (which were filled with hydrogen). You'll still have to put some thought into where the backblast from rocket launchers goes. The same open swivel mounts as recoilless rifles, maybe?

    Have you put any thought into the engines? Gasoline engines are lighter for their power output, but diesel is a lot less flammable.

    I hope you'll be including the cloud-car/spy-basket on your ships. Militarily, they were not that effective, but for an RPG, it could have its uses. I'm envisioning someone on the airship realizing he's being betrayed by someone in the basket, sliding down the cable, pistols get knocked out of hands, and it turns into a wrestling match to see who gets thrown out. Like a fistfight on a mountain cable car.

    Have you seen the old Michael York movie "Zeppelin"? Not a great movie, but an interesting plot and lots of fun for airship buffs, and it's available on DVD.
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    I don't have anything to offer on the topic, but reading this is very entertaining. Thanks, guys!

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    Quote Originally Posted by Sarge View Post
    I've been a zeppelin buff for years. Always wanted to play an RPG with an airship, never had a chance to.
    This original was just to have a bit of background for the setting. Now I start to get to many plot and scene ideas. For example, the idea of a ship having to navigate through the valleys of a large mountain chain, possible controlled by enemies, do have it's appeal


    For ballast, you might want to consider the method modern blimps use to trim their lift. They have ballonets, air-filled bags inside their envelopes, which can be inflated or deflated. Inflated ballonets have more weight and expand into the helium envelopes, compressing the helium and reducing lift. So, that basically means you can use air for ballast. You don't need to carry as much ballast when you can refill it from the air around you, but you'll still want some water ballast for emergency situations.
    Well, as I understand it, a blimp is soft body that is inflated to the point where the pressure is slightly higher than the air around it. So that would mean that inflating those ballonets, the helium is compressed and becomes a bit heavier, and there is a bubble of "heavy" air that can cheaply be vented when needed.

    But a Zeppelin is a hard body construction with helium or hydrogen cells/ballonets that is generally the same pressure as the surrounding air. So the same effect is gained by inflating and deflating different cells. If it is cheap hydrogen, it can just be discarded. But there is a need to preserve the gas, then there has to be valves and pipes to collect it.

    As long the ship is moving, the rudders should be able to compensate a bit for weight displacement as well. But, for example, someone manage to blow away all of the front gas cells, then a water ballast system sounds like a really good idea.

    I'd say your gun crews are undermanned. It was usual to assign at least two men to a Vickers gun, one to shoot and the other to keep the ammo coming and the cooling jacket working. Not sure about the standard crew size for a 75 mm, but I'm guessing more than two, especially if you're trying to maintain a high rate of fire.
    Yes, and intentionally undermanned. To my understanding, a normal crew for a 75 mm is a crew of four. I just don't think it is possible to load, spot, aim and fire a gun from a moving platform against a moving target by yourself; especially when there is nothing to use as reference to how far away the target is. At least from a practical "I want to hit something" point of view. So one man for the machine gun and two for the 75 mm is my take on a minimum.

    I like the idea of airships firing at each other with broadsides of time-fused shells. But if you're trying for realistic engineering, you'll need to account for recoil. Just guessing here, but I don't believe a zeppelin framework could absorb the recoil of a standard 75. Recoilless guns might work, if you made sure the backblast was directed away from the hull. Maybe put the guns in open swivel mounts on the top and bottom of the centerline.

    Another recoilless possibility is rockets. The Russian Katyusha of WW2 was effective and low tech. A few French WW1 fighter planes mounted rockets on their wing struts. Those were somewhat effective against German observation balloons (which were filled with hydrogen). You'll still have to put some thought into where the backblast from rocket launchers goes. The same open swivel mounts as recoilless rifles, maybe?
    I picked the M1916 as it has a recoil system, it do has a shorter range than other 75 mm so I guess it is a bit underpowered, and it has been used as a truck mounted AA gun. It might still need a bit of extra recoil dampening to not put to high stress on the hull. http://en.wikipedia.org/wiki/File:US...ruck_Mount.jpg
    This page gives a few ideas as well http://www.dieselpunks.org/profiles/...lying-gunships

    But I agree that a heavier gun would definitely be a problem. Hm... A swivel on top and bottom would be able to fire to the sides, front and back. But to be able to fire up and down would require one on each side as well. To handle the backward blast when firing, perhaps the "exhaust" is slightly angeled away from the ship. A good question is how they can be reloaded. From that point, rocket launchers with multiple rockets might make more sense; or just a bomb bay.

    There is some appeal to the idea to have internal rocket tubes, to make it fire them as torpedoes from a submarine. But without any form of "program" a heading, as with torpedoes, I don't think there would be much use. At least the WWII torpedoes could be launched at targets that was in quite an angle from the submarines heading.

    Have you put any thought into the engines? Gasoline engines are lighter for their power output, but diesel is a lot less flammable.
    Hindenburg used diesel engines, so that is definitely an option. As diesel engines tend to be better for continuous long time running, that sounds like a good option. Small fast currier airships would probably have gasoline engines. Some ships might even have electrical engines. So I guess engine choice might vary depending on what kind of missions the ship is intended for.

    I hope you'll be including the cloud-car/spy-basket on your ships. Militarily, they were not that effective, but for an RPG, it could have its uses. I'm envisioning someone on the airship realizing he's being betrayed by someone in the basket, sliding down the cable, pistols get knocked out of hands, and it turns into a wrestling match to see who gets thrown out. Like a fistfight on a mountain cable car.
    I had not thought about it. But that sounds like a great option. After all, how could you otherwise spy on the ground, if the ship is hidden in the clouds.

    Have you seen the old Michael York movie "Zeppelin"? Not a great movie, but an interesting plot and lots of fun for airship buffs, and it's available on DVD.
    No, I haven't. Sounds like I should look that one up

  6. #6
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    Run high, run silent

    A dark painted airship moving silently through a moonless sky, slowly closing in on its unaware target.

    What would it require for an airship to be able to sneak through the night or high up in the clouds, out of sight?

    First part would require the option to run silent. Electric motors was for example used in U-boats during the first world war. On a U-boat, the batteries are charged by a generator connected to the diesel engine. But, the main noise is not coming from the engine, but from the propeller. As the tip of a propeller blade tend move with a speed faster than the speed of sound, it creates a sound bang each time it rotates by.

    As a lighter than air craft doesn't need the same amount of thrust as a heavier than air, so it is enough if the propeller rotates slowly enough to not break the sound barrier. Basically, a trade-off between sound and speed. More advanced propellers improves the situation as well. So a trade-off between speed and sound.

    According to wikipedia, brushless DC motors have only been available since the early 60s. So an electric engine has to be a brushed motor. Those are less effective and requires more maintenance.

    It will require quite a few batteries to keep the engines running. The type of batteries would probably be the typical car battery; just larger, and a lot of them.

    The second part is that as the air pressure drops at higher altitude, the lift given by the gas drops with the same amount. The temperature of the air do affect as well. An online calculator to get the air pressure of different heights and temperatures is http://www.digitaldutch.com/atmoscalc/ However, for gaming purposes, having that 850 meters is 0.9atm, 1700 meters is 0.8atm and 3000 meters is 0.7atm. So that eats up 20,000 kg, 40,000 kg, and 60,000 kg of the lift on the example ship.

    So it sounds like a stealthy "submarine" kind of airship would be possible under the above assumptions.

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    Quote Originally Posted by Cpt. Lundgren View Post
    But, the main noise is not coming from the engine, but from the propeller. As the tip of a propeller blade tend move with a speed faster than the speed of sound, it creates a sound bang each time it rotates by.
    The propellers do make a lot of noise, but most engine/propeller combinations are designed to keep the prop tips subsonic. When they break the sound barrier, the efficiency of the propeller drops substantially. With WW1 engines, props were designed to be big and turn slowly; the technology wasn't adequate to rev engines fast enough to turn the props supersonic. I don't believe that was possible until the 1930's.

    As for altitude, a well-designed zeppelin could get high enough that the crew needed oxygen. The "height-climbers" of WW1 were developed to fly above English pursuit planes and anti-aircraft fire. IIRC, they often operated around 16-18,000 feet. So, you might want to think about rules for characters passing out from oxygen starvation if they're at altitude without oxygen masks.
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    Quote Originally Posted by Cut View Post
    I don't have anything to offer on the topic, but reading this is very entertaining. Thanks, guys!
    Glad you like it. Wasn't sure if anyone was interested in my ramblings until you and Sarge posted

    Quote Originally Posted by Sarge View Post
    The propellers do make a lot of noise, but most engine/propeller combinations are designed to keep the prop tips subsonic. When they break the sound barrier, the efficiency of the propeller drops substantially. With WW1 engines, props were designed to be big and turn slowly; the technology wasn't adequate to rev engines fast enough to turn the props supersonic. I don't believe that was possible until the 1930's.
    Ah. Good to know My knowledge is mainly from modern engines. By the way, you don't happen to know about when the technology came to be able to change the pitch of the propeller blade? I'm fairly sure they had it in the early 30s, but I don't think they had it at the outbreak of WWI.

    As for altitude, a well-designed zeppelin could get high enough that the crew needed oxygen. The "height-climbers" of WW1 were developed to fly above English pursuit planes and anti-aircraft fire. IIRC, they often operated around 16-18,000 feet. So, you might want to think about rules for characters passing out from oxygen starvation if they're at altitude without oxygen masks.
    I definitely have to read up on that. 18,000 feet/6,000 meters would mean that the air pressure has dropped to 50% according to the calculator mentioned above. The problem wouldn't just be about oxygen starvation, but also height sickness (bit like bends for divers). Himalaya seems to have quite a bit of problem with tourists that doesn't take it slow enough to acclimate themselves. Now, an interesting question is how a crew, that is stationed on a mountain base, would handle to quickly drop down to sea level, pick something up, and then quickly climb up to that height.

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    Controllable pitch props were cutting edge technology in the early 30's. I worked on one of the early Hamilton-Standard controllable props in A&P school last month. That's a simple design controlled by pressurized engine oil pumped into the hub. Some early controllable props used electric motor servos in the hub to adjust the pitch.

    It is possible to get the bends at high altitude, but not very likely in a zeppelin. They climb fairly slowly, and bends are more likely when pressure drops quickly. Hypoxia symptoms vary from person to person, but usually include blue fingernails and lips, headache, decreased reaction time, impaired judgement, euphoria, visual impairment (loss of peripheral vision and color perception), drowsiness, dizziness, fingers & toes tingling, and numbness. I've experienced a lot of that in an altitude chamber. To show us how it affects us, they gave us a test with simple problems to solve after we'd been depressurized to about 20,000 feet for about a half hour. What I remember most about the test is a simple math problem.

    1,000,000
    +1,000,000

    I looked at that, thought, "I'm good at math. That's easy," picked up my pencil, and looked at the problem. "OK, start at the right end, zero plus zero, that makes zero, write the zero down under the other zeros, carry the one... wait, is that right? This problem is tricky, maybe I'll come back to it later."

    Time of useful consciousness at altitude also varies a lot for individuals, depending a lot on general health and fitness. Smokers don't do nearly as well as non-smokers. According to FAA approved text-books, an average person can expect 30 minutes or more of useful consciousness at 20,000 feet, dropping off to only about 15-20 seconds at 40,000 feet.
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    Quote Originally Posted by Sarge View Post
    Controllable pitch props were cutting edge technology in the early 30's. I worked on one of the early Hamilton-Standard controllable props in A&P school last month. That's a simple design controlled by pressurized engine oil pumped into the hub. Some early controllable props used electric motor servos in the hub to adjust the pitch.
    So a pure WWI setting would not have it, but an "Indiana Jones" setting might. Would be interesting to find out if Hindenburg had controllable pitch propellers.

    It is possible to get the bends at high altitude, but not very likely in a zeppelin. They climb fairly slowly, and bends are more likely when pressure drops quickly. Hypoxia symptoms vary from person to person, but usually include blue fingernails and lips, headache, decreased reaction time, impaired judgement, euphoria, visual impairment (loss of peripheral vision and color perception), drowsiness, dizziness, fingers & toes tingling, and numbness. I've experienced a lot of that in an altitude chamber. To show us how it affects us, they gave us a test with simple problems to solve after we'd been depressurized to about 20,000 feet for about a half hour. What I remember most about the test is a simple math problem.

    1,000,000
    +1,000,000

    I looked at that, thought, "I'm good at math. That's easy," picked up my pencil, and looked at the problem. "OK, start at the right end, zero plus zero, that makes zero, write the zero down under the other zeros, carry the one... wait, is that right? This problem is tricky, maybe I'll come back to it later."
    I didn't know about that effect. Thank you Gives a few interesting options for problems (or advantages if having adapted to high altitudes).

    Time of useful consciousness at altitude also varies a lot for individuals, depending a lot on general health and fitness. Smokers don't do nearly as well as non-smokers. According to FAA approved text-books, an average person can expect 30 minutes or more of useful consciousness at 20,000 feet, dropping off to only about 15-20 seconds at 40,000 feet.
    When I was referring to bends, I was thinking about the symptoms and not the nitrogen dissolving and forming bubbles.
    http://en.wikipedia.org/wiki/Altitude_sickness
    http://en.wikipedia.org/wiki/Decompression_sickness

    The climbing to fast in regard to altitude sickness is not taking days to adapt to the height. The base camps for Mount Everest are on about 18,000 feet, where the climbers stays for days; and climbers not taking time to get to the base camp will risk altitude sickness. I'm not sure if the Hypoxia you are talking about is the same as altitude sickness, or another beast in itself.

    As I can envision a high altitude airship to be on a multiple days missions, having a crew adapted to high altitudes would be a must in that case.

    If I recall correctly (I haven't been diving for over five years now), the recommendations is to wait at least 24 hours before getting on an aircradt. So extracting a diver with a zeppelin might not be the best idea.

    So the ones risking bends would most likely be fighter pilots that wants to reach a high flying airship, if they don't have breathing apparatus.

    Another problem with heights is the temperature, and insulation means added weight. So a hot summer day would still mean winter clothes at 18,000 feet. Going from Cali to Buena Ventura in Colombia was quite interesting in that regard. Cali at 1000 meters above sea level, it was like a warm Swedish summer day; in the mountains (I don't know the height, but at least not over 3000 meters, probably quite a bit less) it was far to chilly to just have a t-shirt on even for a Scandinavian; and then the pressing tropical heat at the coast.

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    Quote Originally Posted by Cpt. Lundgren View Post
    Would be interesting to find out if Hindenburg had controllable pitch propellers.
    I'm not sure about Hindenburg, but I know for a fact that USS Macon did. She also had her props on swivel mounts that rotated up to 90 degrees down. That could produce up to 6000 pounds upward thrust or 8000 downward, from eight engines of 560 hp each turning 16'4" props at 1600 rpm. (book, Airships Akron and Macon, by Richard K Smith)

    24 hours is the recommended wait time between diving and flying. You can minimize the risk by flying at lower altititudes, or by pressurizing the aircraft. I suppose you could install an iron lung in a zeppelin, if it was a really important mission to justify the added weight, and if you really care about what happens to the diver.
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    Quote Originally Posted by Sarge View Post
    I'm not sure about Hindenburg, but I know for a fact that USS Macon did. She also had her props on swivel mounts that rotated up to 90 degrees down. That could produce up to 6000 pounds upward thrust or 8000 downward, from eight engines of 560 hp each turning 16'4" props at 1600 rpm. (book, Airships Akron and Macon, by Richard K Smith)
    The what?!?

    I had completely missed those two. But after all, they are just the second and third largest built, using helium, having controllable pitch, swivel mounts for the propellers, seven machine guns... and had four internal bays for biplane fighters...

    I kind of feel like a school boy at Christmas. They contain almost all of what I have speculated about how an airship could be used, and to Paraphrase Niska "This is fact; is solid."

    The Wikipedia page about USS Macon mentions how the Gas cells would start to leak and eventually rupture when the try to pass some mountains in Arizona. This make me guess that if they had a system to vent gas from the cells, and then recollect it, it was only connected to some cells and not all. Then most of the gas cells might have been sealed ballonets that was only filled to around 80%.

    The Wikipedia page about USS Akron mentions the failure to use spy basket. But the wikipedia page about spy baskets mention how it was successfully used in a raid against Calais.

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    If you look around Youtube, you can find old newsreel footage of USN airships launching and recovering biplanes. Maybe I'm just an airplane nerd, but I think those clips are too cool for words.

    The first hook-ons were performed with the 2-seat Vought UO-1 and USS Los Angeles, which had an external hook, but no way to store an airplane. Akron and Macon also had Consolidated N2Y trainers that they used as "running boats." When those were worn out, they were replaced by Waco UBF's (which had a military designation that escapes my mind at the moment).

    If you're looking for books on Akron & Macon, my first recommendation is The Airships Akron and Macon by Richard K Smith, followed closely by Sky Ships by William F Althoff, and Sky Ship - The Akron Era by Thom Hook.
    + &lt;&lt;&lt;&lt;<

    Blessed be the Lord my strength, which teacheth my hands to war, and my fingers to fight. Psalm 144:1

  14. #14
    Join Date
    Mar 2000
    Location
    Jacksonville, Arkansas, USA
    Posts
    1,880
    Thank the historians of the USN for preserving these photos:
    http://www.history.navy.mil/photos/a...types/zrs5.htm

    And thank a highly dedicated and skilled model builder for these:
    http://www.ciderpresspottery.com/ZLA...vault/eds.html
    + &lt;&lt;&lt;&lt;<

    Blessed be the Lord my strength, which teacheth my hands to war, and my fingers to fight. Psalm 144:1

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