Second London Naval Treaty
All RN fleet carriers had hangar heights, except the two "Implacable"-class ships, which had heights, and "Indomitable" which had a lower hangar and a upper hangar. The "Illustrious" class had a single high hangar that was long. Within the confines of ship design, and the Second London Naval Treaty to which they complied, the "Indomitable" and "Implacable"-class carriers had to accept a reduction in hangar heights (to keep the metacentric height within acceptable limits) and size, and as a result, had some restriction on aircraft types supplied via Lend-Lease. IJN carriers typically had high hangars, including "Taihō" and "Shinano". The USN had hangar heights while the "Yorktown", "Wasp", "Essex", and "Midway" classes had hangar heights.