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Or, to be more precise why was the Type-C hangar so tall? Built in the 1930s across many airfields in the UK, it was built with a higher roof (11 m) than any contemporary aircraft. (higher even than the tail of the worlds largest aircraft the Tupolev ANT-20)

Even by the end of WW2 it was still higher than any UK aircraft, even the American flying fortress could fit in (height wise)

So, why so tall? were they expecting future aircraft to be much higher? Was it also intended to house blimps? or is there some other reason?

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6 Answers 6

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Gantry cranes. Buildings where people work on big machines usually have high ceilings, and often those ceilings leave space for gantry cranes. The cranes may have been removed or never installed.

This is not specific to aircraft.

Spacecraft:

enter image description here

Trains:

enter image description here

Submarines:

enter image description here

Turbines:

enter image description here

It would be quite hard to perform an engine change on a Handley Page H.P.54 Harrow (1936) without a big crane. Engines needed more frequent maintenance back then.

enter image description here

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    $\begingroup$ Video clip of a gantry crane used for A380 construction: youtu.be/_-S2tzxYPD0?feature=shared&t=140 The ceilings are still quite high in modern aircraft facilities. $\endgroup$ Sep 3, 2023 at 11:29
  • $\begingroup$ More gantry crane: commons.wikimedia.org/wiki/… $\endgroup$ Sep 3, 2023 at 11:29
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    $\begingroup$ Not just the crane itself, but as the photos show, the ability to do anything useful with the crane requires anything up to the aircraft's height again to move components above it. $\endgroup$ Sep 4, 2023 at 7:09
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    $\begingroup$ @TobySpeight I think this drives the height the most. The crane itself doesn't take a huge amount of space, but if (in the extreme case) you want to lift one aircraft over the other, you need a very high clearance $\endgroup$
    – ROIMaison
    Sep 4, 2023 at 8:11
  • $\begingroup$ Yeah, you also need to be able to move stuff on top of other stuff, where both stuffs are commonly very bulky. $\endgroup$
    – yo'
    Sep 4, 2023 at 13:24
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11 meters isn't tall. You should see a modern hangar...

enter image description here

Note how much headroom there is between the tip of the tail and anything on the roof that could potentially damage it.

The aircraft doesn't always sit perfectly level on its gear, the roof can sag, the floor can be uneven, there's lights hanging from the roof, and you have people working on the aircraft. Even more headroom was desired in hangar design, because aircraft were getting larger every year, and it wasn't easy to predict this growth.

Most British bombers kept using twin tails, which result in a lower total height than a single tail. Yet, there were single-tail proposals, and had one won, the plane would've been taller. Twin tails stayed, so they lowered the roof eventually. Large single-tailed American bombers, like the B-29 and B-32, would've been too tall for the Type C hangar. So would the Britain' own Short Sunderland.

So, headroom was provided both for practicality and for future aircraft which might have been taller than they turned out to be.

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Well the Lancaster bomber was almost 7 meters from the ground, which doesn't leave huge amounts of clearance if you need to jack up the aircraft. Remember, these are maintenance hangars. Notice how every car workshop you go to has tall ceilings too!

The ANT 20 you mention was 10.6 meters - bearing in mind the height of the hangar isn't the same as the internal usable space, or indeed the door opening height, it seems it would be unlikely to fit at all, let alone be an excessive design

Your own link then goes on to say that as designs did normalise and we reached what seemed to be the reasonable limits for bomber design, that the hangar design changed and the roof dropped.

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    $\begingroup$ According to the OP's link (en.wikipedia.org/wiki/Type-C_hangar), the door height actually is 35 ft, while the "clear height" inside is 35 ft 4 in. So they did think of future-proofing by making the doors about as high as the lowest points on the ceiling, and yeah Wikipedia does seem to be saying intentional future-proofing and flexibility was a consideration for RAF hangars. $\endgroup$ Sep 3, 2023 at 18:22
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Other design considerations for any industrial building, not just aircraft storage, maintenance or manufacturing, are lighting, ventilation, separation of incompatible processes & fire control.

Higher ceilings facilitate better indirect, shadow-free lighting from natural sources or extremely bright point sources, out of eyelines.

Airspace over work areas improves natural circulation of fresh air & dispersal of paint, solvent & cleaning vapours, hot work gases & smoke. It promotes a safer & less noisy work environment.

You do not want the carpentry power tools creating sawdust clouds rolling along the ceiling into the welding bay. You don't want the machinists having to go outside to turn around a 20 foot length of stock to avoid the spray painters because they can't end-over-end it.

Fire can spread faster & be harder to isolate & fight effectively in a constricted space. It is helpful to be able to use firehoses from a safe(r) distance while remaining inside the structure. The aircraft of the first half century of aviation were outrageously flammable. High ceilings ameliorated this while delaying smoke saturation to some degree.

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  • $\begingroup$ Very good points $\endgroup$
    – sophit
    Sep 4, 2023 at 15:15
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Hangers were originally enormously high, because they were first built to accommodate airships. Dumping an airship on the floor would wreck it: they did not have undercarriage (at least, not for the bow and stern), they were up to 900 feet long, all the important stuff was along the keel for stability, and the whole framework was designed to be in tension, not compression. The main circular frames were designed like spoked bicycle wheels.

The building are called hangars literally because the airship was hung from the roof, before the hydrogen was vented for safety, and maintenance could begin.

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    $\begingroup$ Welcome to Av.SE! $\endgroup$
    – Ralph J
    Sep 4, 2023 at 13:47
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    $\begingroup$ To be a pedant, hangar is the French word for barn. $\endgroup$ Sep 5, 2023 at 8:47
  • $\begingroup$ @DavidMarshall Rats! Hoist by my own firecracker! $\endgroup$ Sep 5, 2023 at 12:54
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    $\begingroup$ The type C hangar is nowhere near big enough for an airship at that time. Also, it seems the type C was built for the RAF, but I see no indications the RAF ever had airships. Almost no hangars were designed with airships in mind. For those that were, it is obvious from the shape. $\endgroup$ Sep 5, 2023 at 21:30
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They must be that high because its an C shaped construction, all C shaped halls are like this, the benefit is a roof that dont need supporting down to the ground inside the building, this gives you a fully open and large areal with no obstructions... The same goes for thoose who wonders why they C shape a tunnel roof. The fysics behind the C shape are well explained.

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  • $\begingroup$ The "type-c" in the name doesn't refer to the shape of the hangar which is actually parallelepiped... $\endgroup$
    – sophit
    Sep 4, 2023 at 15:21
  • $\begingroup$ Sorry, U shape is more correct, or bow. But the answer to why they need to be so tall is still the same, the shape of the construction need to be like that because it equalizes the forces from the top down to the ground trough the "bow" shape into the sidewalls. its a self carrying roof structure with no need for supports to the ground level. $\endgroup$
    – user70710
    Sep 4, 2023 at 18:16
  • $\begingroup$ Understand, anyway all the hangars for example in the pictures of the other answers have a simple flat roof, no inverted-U shape $\endgroup$
    – sophit
    Sep 4, 2023 at 18:38
  • $\begingroup$ A related issue with regard to roof height and pitch has to do with snow accumulation. A steeper roof will be incapable of holding as much snow as a shallower one. In some climates, snow accumulation would not be a design consideration, but in other areas a steeper roof may be cheaper than a shallower one which could support the amount of snow that might accumulate. $\endgroup$
    – supercat
    Sep 4, 2023 at 18:49
  • $\begingroup$ Kinda vaguely right - airship hangers were often very high for their width and the outer layer described a catenary curve. But that's specific to airships which were taller than their width. And the lack of internal supporting posts is definitely a benefit for parking anything big and unweildy. $\endgroup$
    – Criggie
    Sep 5, 2023 at 23:23

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