Aircraft Carrier Design Question

[Eternal_Freedom]

Ok this is a rather random question but it's one I've never managed to find an explanation for. Why is it that British/American/French/Russian/Spanish/Italian etc carriers are built with the island superstructure on the starboard side, while Japanese carriers in WW2 had them on the port side?

[Captain Seafort]

Ok this is a rather random question but it's one I've never managed to find an explanation for. Why is it that British/American/French/Russian/Spanish/Italian etc carriers are built with the island superstructure on the starboard side, while Japanese carriers in WW2 had them on the port side?

Most Japanese carriers had starboard side islands as well. The only ones with port side islands were Akagi and Hiryu, with the theory being that it would make it easier to operate as pairs with Kaga and Soryu - one would operate a clockwise circuit, the other would operate the standard anticlockwise circuit. Wiki (sourced to Norman Friedman's "British Carrier Aviation: The Evolution of the Ships and Their Aircraft") gives the reason for this as pilots instinctively breaking to port after an abort.

The experiment didn't work, Akagi and Hiryu had problems with accident rates much higher than their semi-sisters, and all subsequent designs had standard starboard side islands.

[Adam Reynolds]

Most Japanese carriers had starboard side islands as well. The only ones with port side islands were Akagi and Hiryu, with the theory being that it would make it easier to operate as pairs with Kaga and Soryu - one would operate a clockwise circuit, the other would operate the standard anticlockwise circuit. Wiki (sourced to Norman Friedman's "British Carrier Aviation: The Evolution of the Ships and Their Aircraft") gives the reason for this as pilots instinctively breaking to port after an abort.

The experiment didn't work, Akagi and Hiryu had problems with accident rates much higher than their semi-sisters, and all subsequent designs had standard starboard side islands.

I wonder why it was the case that pilots always banked in the same direction?

[Esquire]

Off the top of my head, maybe the flight schools had mockup carrier islands on the starboard side of the landing strip?

[Raw Shark]

Or left is just the instinctive direction of, "Fuck no!" for the 90% of the population that happens to be right-handed?

[Borgholio]

Or left is just the instinctive direction of, "Fuck no!" for the 90% of the population that happens to be right-handed?

More than likely, you are correct. A quick google search told me that standard air traffic patterns are often counterclockwise (to the left) and the first carriers mirrored that in their design.

[Raesene]

I can't find the citation, but I read somewhere that the propeller spin had the aircraft turning more easily to the left than the right, so evading in that direction was easier.

[Borgholio]

That's true too, the Sopwith Camel was notorious for that. They could turn on a dime to the left, but they were a whale when banking to the right.

[Eternal_Freedom]

I figured it was something like that (the propeller spinning thing) but I was stumped as to why some Japanese carriers didn't. Though I can see why they decided to try it.

[Sea Skimmer]

I can't find the citation, but I read somewhere that the propeller spin had the aircraft turning more easily to the left than the right, so evading in that direction was easier.

That appears to have been the original issue yes. In WW1 aircraft propellers usually spun clockwise, if you were looking at the engine from the front. No reason it had to be that way but human brains simply tend to favor that direction because it's what were used to seeing from clocks ect..

From the pilot point of view though that means the aircraft wants to roll to port/left from the torque of this. This effect only got stronger the bigger and more powerful the engines got, trim adjustments being used to prevent the aircraft from actually flipping over in flight. This issue actually began to make the last models of piston engine fighter hard to control as they got well past 2000hp engines, and was a major factor in why everyone's the short lived turboprop fighters all had contrarotating propellers.

This effect was also significant enough as a reason for piston engine nuclear bombers to break left after releasing the bomb.

Once you had one carrier with the island on the starboard side everyone would be trained with the carrier that way and the system simply had a tremendous interia in favor of not changing it. All the more so since as naval air forces grew pilots usually got their initial carrier training on the oldest carriers in the fleet.

It also worth recalling that the very earliest carriers like HMS Furious in RN service didn't have full length flight decks at all, and as one might imagine pilots crashed massively trying to land on a stub ended runway with a superstructure in front of it. So a lot of safety concern had already been forced onto designers, and the designers had serious time to think about it, by the time any island carrier existed. WW1 era planes had utterly horrendous accident rates.

[Adam Reynolds]

This effect was also significant enough as a reason for piston engine nuclear bombers to break left after releasing the bomb.

I would have thought that a multi engine aircraft would have engines that spin in different directions.

[Borgholio]

Typically they would, but in WW2 they needed mass production more than anything else, so it was easier to just supply thousands of the same kind of engine and deal with the left-hand torque issue. To have counter-rotating engines means two different production lines, or at the very least, extra parts. Some engines simply used a different crankshaft, but others were wholly different designs.

[Eternal_Freedom]

And presumably the set of engines spinning the other way would only be useful for multi-engine bombers and other planes and of no benefit to fighter production. I can see why they decided not to bother and (presumably) train pilots to deal with it.

[Sea Skimmer]

Sometimes they do and did in the War, but in the World Wars that then requires the production of separate 'right' and 'left' handed engines with different reduction gearing as noted.

On the modern A400M, which couldn't use contraprop because they'd never comply with modern noise regulations, and have become less necessary for power absorption anyway, they have one engine spinning each way on each wing. Thanks to the greatly improved technology of the modern day, and the aircraft costing a bloody fortune, it has engine transmissions which all have the gearing needed for both right and left handed operation, though it still requires minor physical changes on the ground prior to installation to enable running one way or the other. This would have been very expensive to do in WW2 when gear cutting was a bottleneck for just about everything. Hardest steels around being cut with precision teeth during a tungsten shortage!

End result was all the B-29 engines spun clockwise and the aircraft wanted to veer rather badly on takeoff, before it was going fast enough for the stabilizer to work right, around 80mph being the relevant minimal speed. Until then you had to use one wheel brake and slightly reduced power on the right wing to hold it even on the runway. Once it was airborne it wasn't a major problem because bombers are well, bombers. However it was more then relevant enough to be taken advantage of for the nuclear bombing runs. I'm pretty sure all American bombers were this way too, it was just most noticeable on the B-29 because it was the biggest plane around.

[Jaepheth]

I can't find the citation, but I read somewhere that the propeller spin had the aircraft turning more easily to the left than the right, so evading in that direction was easier.

That appears to have been the original issue yes. In WW1 aircraft propellers usually spun clockwise, if you were looking at the engine from the front. No reason it had to be that way but human brains simply tend to favor that direction because it's what were used to seeing from clocks ect..

It's been awhile since I took mechanics, but wouldn't spinning in that direction give a torque pushing into the aircraft instead of pulling out (by the right hand rule)? And I imagine compression is easier to build a bearing for than tension.

[Borgholio]

It's been awhile since I took mechanics, but wouldn't spinning in that direction give a torque pushing into the aircraft instead of pulling out (by the right hand rule)?

He might have meant counter-clockwise from the front. Many propellers rotated clockwise as viewed from the pilot's seat.

[Elheru Aran]

And yes, there was torque. This was a particular problem with the Sopwith Camel, as mentioned before. Later planes tried to counter it with things like longer wings and such, but it was always a bug. It got to where pilots had to be carefully trained to *not* always break in the 'easy' direction with torque assist, IIRC....

[Isolder74]

Most dogfighting instructions told pilots under attack to break left as that gives the pilot the smallest turning circle and therefore the best chance of countering whatever move the enemy made. You only really want to break right if being attacked from the right as turning left would still put you under the enemy guns for longer.

Sometimes the correct action against an enemy depended on the capabilities of the enemy aircraft as diving away was usually the best thing to do in a Wildcat against a Zero as that plane was better at almost anything else but that(even in a dive it was too but not as bad) and climbing against a Zero was suicide.