Use of Zepplins in the U-boat war

We don't need wiki.

We know that a number of Zeppelins (even if not 100%) were shot down by planes using one or two Lewis guns (firing at about 600rpm each or bit better) using 97 round drums of less than 100% incendiary ammunition. (Yes some pilots did change drums during a single attack/engagement).

The Idea that a Zeppelin in 1940 would be 'survivable' when attacked by a plane with four or more machine guns firing at 1100-1200rpm (over four times the rounds per sec and as much as ten times) that are belt fed (no pauses for reloading. This take no account of improvements in the incendiary ammunition or perhaps a different scale of issue?

In any case see .303 inch Incendiary - British Military Small Arms Ammo

for a history of British incendiary .303 ammunition.

Please note that the WW I ammunition started "burning" as soon as it left the gun barrel so the amount of incendiary material varied greatly with the range.
The WW II ammunition didn't start burning until impact (which might be questionable on balloon fabric but not on structure).

A difference between setting fire to an airplane compared to a Zeppelin is the airplanes fuel tanks are the size of 2-3 55 gallon drums for most fighters or 10-15 drums for a twin engine bomber and for the Zeppelin the flammable gas bags are the size of a large apartment building.

DerAdlerIstGelandet said:

And even if it was "no more dangerous than avgas", that would make it bad enough.

I set an aircraft fuel bladder on fire simply by using an electric drill in the vicinity of it. Pulled the trigger, and FOOSH, a 3 foot flame shooting out the bladder opening.

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And how are those eyebrows now? Are they back yet...?

DerAdlerIstGelandet said:

And even if it was "no more dangerous than avgas", that would make it bad enough.

I set an aircraft fuel bladder on fire simply by using an electric drill in the vicinity of it. Pulled the trigger, and FOOSH, a 3 foot flame shooting out the bladder opening.

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Bet that was an attention getter!

BiffF15 said:

Bet that was an attention getter!

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Yup, fortunately the tank was junk anyhow, so I did not get in any trouble. The things that happen to young A&P's learning...

Peter Gunn said:

And how are those eyebrows now? Are they back yet...?

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I was far enough away when it happened. I was opening up a panel on the wing.

I don't know the proper air fuel ratio for hydrogen but I know it makes a loud bang. It was 1958 or 59 which ever year I took high school chemistry, that a friend and I decided to make a hydrogen generator the way we had just learned in school. There was a local Union Carbide facility in our residential neighborhood that took up most of the block. It was fenced with a small second fenced enclosure near the gate. We knew they kept acid locked in it. We waited till a man brought out a small plastic drum to put into the cage and asked him for a quart so we could get extra credit in a chemistry class project. He gave us a small amount and told us it was depleted acid. We went to a restaurant for oyster shells and set up our generator in the attic of my friends 's garage. The "depleted" acid tested positive for both nitric and hydrochloric acid. The generator worked fine blowing up balloons until we saw they were blowing up larger and larger and keeping us busy, and the vessel was getting too hot to touch. We shut it down with baking soda and emptied it out side. His dad never understood why grass would n't grow in that spot. The balloons were fitted with fuses silmilar to cherry bomb fuse which was available then. We Stood on the balcony of the attic, lit the fuse and let the balloon go. At about 60 feet up the explosion brought people outside and shook leaves out of the trees. After about four balloons, we saved the others till after dark. We never figured what Union Carbide used that created the "depleted" acid.

The advantages of hydrogen for airships was its availability and the ease by which it could be manufactured, and its lifting properties, you need less hydrogen than helium to lift a given load.

Hydrogen is extremely volatile. That is a given. It's how its managed and as I said, the British had very few incidents involving hydrogen compared to the Germans because of quality control, but when they did have incidents it resulted in fire and destruction of 'ships and infrastructure.

Always annoys me when the dangers of Hydrogen are pointed out. Like avgas and petrol are perfectly safe and no flying machine has ever caught fire. Oddly more people survived the Hindenburg fire than were killed. If it was avgas instead of Hydrogen then that would have been less likely.

Helium is inert and so has no risk of fire.

Any large aircraft in WW2 faced with a well armed fighter is going to be in for rough ride. It would be something to do a statistics analysis of the Zeppelin v a Gotha on which was the better bet in UK raids during ww1.

In my view the use of Hydrogen is a calculated risk which is no worse that avgas. Or the Germans were stupid.

The Basket said:

Oddly more people survived the Hindenburg fire than were killed.

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This is true; more people died in the Akron disaster, but Hindenburg's loss certainly did nothing for hydrogen's reputation. Part of that comes from the fact that it was the first man made disaster captured live on radio and film, so imagine the impact seeing that for the first time in moving pictures would have had on people. To this day, watching it is extraordinary.

The interesting thing about the Hindenburg fire, is that the fire rapidly consumed the skin and burned in areas where there were no hydrogen bags. In watching the footage, you can see the fire quickly spreading and then the dull hydrogen flames billow out the top (no pressure so no massive explosion) and the ship started descending.

Also, storing Hydrogen is far more dangerous than being in an airship's bag, because in order to store the gas, it takes a great deal of volume under pressure.

Part of the Hindenburg disaster was due to the fabric envelope. It was "painted" with some of the standard aircraft "dopes" of the day which were highly flammable in their own right once they got going.

From Wiki so correction is welcome;

"Aircraft dope is a plasticised lacquer that is applied to fabric-covered aircraft (both full-size and flying models[1]). It tightens and stiffens fabric stretched over airframes, which renders them airtight and weatherproof.[2]

Typical doping agents include nitrocellulose, cellulose acetate and cellulose acetate butyrate. Liquid dopes are highly flammable; nitrocellulose, for instance, is also known as the explosive propellant "guncotton".

The bit about gun cotton might need some correction or clarification. Gun cotton was too violent to use as a propellant although it was used as an explosive in early under water mines and torpedoes as it is much less sensitive to water/dampness. There are nitrocellulose propellants but the the ratios or percentage of the basic chemicals are different.

The HIndenburg fire was also fueled by the pigment used in the "dope". To get that nice shiny silver color powdered aluminum was put in the paint/dope.
Before somebody gets the bright idea of using camouflage paint on a Zeppelin they wanted a light reflective color so as to minimize the heating of the envelope from the sun during daylight. The higher temperatures would cause the gas to expand and give more lift (the gas bags usually had some slack in them) and gas would have to be vented to prevent the airship from rising. Problem then comes at night when the gas cools off, the bags shrink and lift is lost. How much spare hydrogen must be carried?

Some airships had systems that would recover the water from the exhaust of the engines (the Hindenburg did not) to use as ballast to partially compensate for the fuel being burned off so they wouldn't have to vent as much lifting gas (of either type) as the airship got lighter.

What was done in WW I on cross channel flights might not work so well on trans Atlantic flights (or " patrols" of several days)

The Basket said:

If it was avgas instead of Hydrogen then that would have been less likely.

Helium is inert and so has no risk of fire.

Any large aircraft in WW2 faced with a well armed fighter is going to be in for rough ride. It would be something to do a statistics analysis of the Zeppelin v a Gotha on which was the better bet in UK raids during ww1.

In my view the use of Hydrogen is a calculated risk which is no worse that avgas. Or the Germans were stupid.

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If you replaced the hydrogen with avgas the thing would have never gotten out of the hanger

You are missing the point about the volume/target size. The Fuel tanks on many WW II aircraft are only a small percentage of the internal volume. Many aircraft took dozen of hits without any hitting the fuel tank/s, others were not so lucky. While the Hydrogen bags did not fill 100% of the envelope of a Zeppelin they did occupy a very large percentage of the internal volume.

The British did some testing at the start of WW II and found that the old WW I incendiary ammunition only set fire to Blenheim fuel tanks (fired at from the rear at about 200yds range) with about 1 round in 10 (tens hits were needed to set the tank/wing section on fire) the new incendiary ammo needed 5 rounds to start a fire on average.

One should note that the Germans pretty much stopped using Zeppelins to attack London in early 1917. there were 22 raids in 1916, there were 6 in 1917. a few of the 6 raids went on through the summer but the Gothas took over.

See this website for an account.

Defeating the Zeppelins | The National Archives

Yes it sometimes took 3 firing passes to set fire to a Zeppelin but that was using a single Lewis gun and no more than 300 rounds of ammo. There may have been other unsuccessful attacks.
A Blenheim fighter has 4-5 guns firing twice as fast and has 500 rounds for each gun.

Something that has not been brought up, though, is that the Zeppelins had defensive positions atop (on the airship itself) and below (in the gondolas) and there was also a tail-gunner position. If memory serves right, they were using the MG08.

Approaching a Zeppelin was not as easy as just flying up to it and hosing it down, you were coming under serious defensive fire.

Goering scrapped the Zeppelins early doors so this is pure conjecture.

Why he did not so sure.

As a former pilot maybe he didn't like them or thought them of dubious military use and thought the Aluminum was better used elsewhere.

In American service, airships were not as successful and was a disaster in bad weather. Oddly a Zeppelin they had was far more successful.

Bad weather was the Achilles heel of blimp use.

If I remember correctly, two of our airships were Zeppelins taken as war reparations.

Speaking of Airships, the Airport I work at is a former WW2 US Navy Airship base. It was used to patrol the Gulf of Mexico during the war. Unfortunately only part of the huge Airship hangar exists today, along with a few bunkers.

DerAdlerIstGelandet said:

I was far enough away when it happened. I was opening up a panel on the wing.

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Ahh... sez you.

Seriously, glad you were that far away, that kind of stuff can fall deeply into the "Not Funny" category.

Peter Gunn said:

Ahh... sez you.

Seriously, glad you were that far away, that kind of stuff can fall deeply into the "Not Funny" category.

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Oh agree. I was close enough to ignite it obviously, but just out of reach. It was pretty embarrassing.

PBS Nova did episodes on the Hindenburg, conclusion was the doped fabric with powdered Aluminum paint and static starting the fire, and another on the invention of the incendiary round that put an end to the Zepplin threat over London. I think I saw them both on NetFlix or Amazon Prime

A number of things I remember from books and the unedited film are interesting. One book told of an old lady making her first air flight slowly walking toward the exit while the ship is falling and others are jumping simply stepped out and walked away unhurt. In the film you can see a man close to the fire have his hair catch on fire. Too much hair dressing. Also, not always shown is when the navy ratings who were to catch the ropes are running towards the camera, a chief steps into view, points toward the ship and can be seen yelling. Navy personnel do a 180 and run toward the fire and begin helping survivors. One tough and scary chief.

special ed said:

If I remember correctly, two of our airships were Zeppelins taken as war reparations.

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The U.S. received no wartime Zeppelins as they were "scuttled" by their crews.
Luftschiffbau Zeppelin did build an airship for the USN, which was (ZR-3) USS Los Angeles as reperation in 1924.

The USN airships were:
(ZMC-2) built by Detroit Aircraft Factory, Michigan (all metal airship)
(ZR-1) USS Shenandoah, built by Naval Aircraft Factory, Philadelphia
(ZR-2) RN-R38 built by Short Brothers, Britain
(ZR-3) USS Los Angeles built by Zeppelin, Germany
(ZRS-4) USS Akron built by Goodyear-Zeppelin, Ohio
(ZRS-5) USS Macon built by Goodyear-Zeppelin, Ohio