Aircraft Carrier and Aircraft Limits

[Zipper730]

This is fairly naval aviation specific, but I'm curious if what requirements existed in terms of the following for operation off of the various carrier classes used by the US, UK, and Japan during the war.

1. Maximum allowable aircraft dimensions
2. Maximum takeoff & landing weights
3. Maximum catapult end-speeds, and arrester hook engagement speeds

It might sound strange but, I've never heard discussed before on this forum before.

 

[RCAFson]

This is fairly naval aviation specific, but I'm curious if what requirements existed in terms of the following for operation off of the various carrier classes used by the US, UK, and Japan during the war.

1. Maximum allowable aircraft dimensions
2. Maximum takeoff & landing weights
3. Maximum catapult end-speeds, and arrester hook engagement speeds

It might sound strange but, I've never heard discussed before on this forum before.

All these factors existed. For the RN FAA, maximum carrier aircraft design dimensions were length = 40ft, folding wing dimensions = 19ft and parked height = 14ft. These dimensions were dictated by elevator dimensions and hangar height. Several carriers had larger elevators and could accommodate unfolded wings of up to ~40ft width, but in general, these were aircraft adapted from RAF types.

TO weight was dictated by carrier flight deck length and carrier speed (hence the use of the Swordfish and Albacore) and by catapult weight limits. Similarly landing speed was dictated by arrestor hook strength limits. I don't have exact numbers for these handy, but catapult limits initially were 11000lb to 66 knots for the armoured carriers, and 7000lb to 56knots for the earlier carriers. Higher weights could be accommodated but with lower terminal speeds.

 

[pbehn]

This is fairly naval aviation specific, but I'm curious if what requirements existed in terms of the following for operation off of the various carrier classes used by the US, UK, and Japan during the war.

1. Maximum allowable aircraft dimensions
2. Maximum takeoff & landing weights
3. Maximum catapult end-speeds, and arrester hook engagement speeds

It might sound strange but, I've never heard discussed before on this forum before.

That must only be because you don't read threads on naval aircraft. Aircraft dimensions were dictated by the lifts, hanger height and general space available. British hangers were lower than USA so they couldnt always operate the same aircraft. The Corsair F4U was too high with folded wings for British ships so it had a shorter wingspan in the RN which gave a higher sink rate and less "float" over the deck. The huge number of take offs and landings by Eric Brown were in part doing research into arrester cables and catchment systems. Maximum take off weight wasnt a constant even on the same mission on the same carrier. On a mission with planes parked on a deck the planes at the front cant take off with the same weight as those at the back, because they have less take off run up (I read here). In short, its all complicated.

 

[36feet10inches]

In short, its all complicated.

Immensely, by the sound of it!

 

[pbehn]

Immensely, by the sound of it!

There are some very learned posters here, it never occurred to me that fighter bombers on a carriers deck would have a different load front to back but when you see that those at the front have a much shorter take off run, its obvious. My background is in metal testing, I presume if enough airplanes come in too fast and too heavy it will be the poor pilot who makes the textbook landing that eventually snaps an arrester wire. From another forum by a poster named Bigglesworth about Winkle Brown and carrier landings "For an idea of the amount of flying he was doing, there's a section in his autobiography Wings on my Sleeve about carrying out trials with a Seafire; he did a batch of ten landings with progressively lower wind-speed, pitching forward and fracturing the prop on the last one, at which point he popped back ashore for the next aircraft and did a second batch of landings with different arrestor cable settings. Another time, carrying out trials with a Mosquito, he carried out five landings one day, the following day they progressively increased the landing weight, on the third attempt the claw of the arrestor hook sheared off bringing a temporary halt to proceedings. Later on in 1945 he notes that he was averaging four or five flights per day, sometimes seven or eight, and that was after a second pilot had taken over working up the Sea Fury. There's an example of one of his busier days, flying eight different aircraft, taking off from 0810 to 2010 for flights of 30-60 minutes (though no carrier landings that day, just dummy deck landings with a Sea Hornet). Brown was also something of a workaholic, seldom taking leave.

 

[pbehn]

An aircraft only has a weight when it is parked, when in the air it has energy/momentum/force there are many ways to express it. In ideal conditions the carrier in at sea sailing into a headwind and it lands so that energy is absorbed by the landing gear and the arrestor hook. In the worst condition the carrier is stood still in no wind and the plane either floats across the deck so all energy is taken by the wire and hook or it pancakes down and all energy is taken by the landing gear. In between all these extremes are a range of speeds and weights for the plane and the ship and assumptions of pilot skill that result in "guidelines" and "instructions" that boil down to a weight, but there are many other factors involved along with that weight.

 

[Admiral Beez]

This is fairly naval aviation specific, but I'm curious if what requirements existed in terms of the following for operation off of the various carrier classes used by the US, UK, and Japan during the war.

1. Maximum allowable aircraft dimensions
2. Maximum takeoff & landing weights
3. Maximum catapult end-speeds, and arrester hook engagement speeds

It might sound strange but, I've never heard discussed before on this forum before.

I was just thinking about this very question as I looked at this image of what must be near the limits of what a British carrier can spot on the deck. HMS Formidable in Far East 1944. THE FLEET AIR ARM AT SEA, JULY 1944

They RN had come a long way from small air groups.

Maximum allowable aircraft dimensions.

The Japanese suffered badly for space by neglecting to have folding wing fighters and dive bombers. They could have set lower limits for maximum allowable aircraft dimensions when stored. They also suffered from terribly designed hangars, with inconsistent hangar widths - imagine how many aircraft Akagi could have carried had her hangar looked like HMS Indefatigable at bottom below in 1944 when the latter was operating 81, all folding aircraft.

Did the Japanese hang aircraft from the rafters like the USN and RN did? These were partially disassembled in HMS Indefatigable's case below.

 

[pinehilljoe]

related, were there any studies of angled decks during the War? Imagine if the later Essex's were completed with SCB-125 angled decks, how that would have helped deck operations.

 

[Admiral Beez]

related, were there any studies of angled decks during the War?

No, this is a 1950's invention. Flight deck - Wikipedia

 

[pbehn]

Does an angled deck carrier sail with the bows facing into the wind or the line of the angled deck?

 

[syscom3]

The view of the Akagi clearly shows its original design as a battle cruiser and how that impacted the capacity of the hanger deck.

 

[Admiral Beez]

The view of the Akagi clearly shows its original design as a battle cruiser and how that impacted the capacity of the hanger deck.

Yes, but that didn't force the Courageous or Lexington class to have such a hangar layout. While it's generous to refer to her as a BC, here's the former battlecruiser Furious' hangar. Followed by USS Lexington's hangar. The Japanese could have made rectangular hangars if they'd wanted to, but it entails tearing the original battlecruiser structure down a lot more.

\\

But having folding wing fighters and dive bombers would be been a greater benefit to the IJN than a quadrilateral hangar. Yes, the USN also had non-folding dive bombers, but when you're the under dog you need more aircraft per deck. Did the Japanese ever field a folding wing dive bomber? The Yokosuka D4Y that followed the pre-war Aichi D3A shared the latter's fixed wing.

 

[GregP]

Essex class carriers (Essex, Yorktown, Intrepid, Hornet, Lexington, etc.) were designed after CV-6 (Enterprise). They had 215 officers and 2,171 men, but crews were some 50% larger by war's end. None were sunk. They usually had 36 fighters, 36 dive bombers, and 18 torpedo planes. They had twelve 5-inch, 38 caliber guns, 17 quad 40's (Bofors), and 65 single Oerlikon close0in defense guns. The 5-inch guns had a range of 10 miles and a rate of fire of 15 rounds per minute. VT shells would detonate when they came within 70 ft of an aircraft.

The standard elevator was a 60 ft by 34 ft rectangle, at least early on with the short-hull Essex class ships. The long-hulls had a bigger elevator, I believe.

The F6F Hellcat could gross out at some 12,600 lbs, the TBF/TBM at about 15,500 lbs, and the SB2C at about 16,600 lbs. I am not intimately familiar with the landing speed since it is possible they could drag it aboard with power at slower than normal power-off stall speeds. The Hellcat stall speed at max weight was 84 mph (73 knots) and the carrier could make 32 – 33 knots. Power-on stall speed in landing configuration was 79 mph (69 kts). Let's assume they would approach at 90 mph (78 kts) for some margin and the ship was making 30 kts into zero headwind wind. The approach speed would be 48 kts and the momentum would be mV, where m = mass in slugs and V = velocity in feet per second. The approach speed of the SB2C Helldiver was supposed to be 85 kts, so it's speed over the deck when the carrier was doing 30 kts would be 55 kts minus whatever headwind was available. I'd assume that would be the max energy a U.S. WWII carrier had to dissipate on landing since the Helldiver was heavier than the TBF / TBM. Not a few early Helldivers were lost to not being able to achieve takeoff speed before reaching the end of the carrier deck. Later, a more powerful engine and a 4-blade prop helped a lot. Once the issue were fixed, the Helldiver did good work.

It wasn't a much-loved airplane but, in carrier service, the SB2C delivered more than four times as many tons of bombs on target as the SBD - 10,994 tons versus 2,524 tons. Land-based, it was the other way with the SBD delivering 18,147 tons versus the SB2C's 1,086 tons. That is more of a function of the SB2Cs being much more on-ship rather than primarily on land, and a LOT of people fail to recognize the SB2C's contributions just because they have a soft spot for the SBD, as do I.

The same can be said for the old Corsair versus Hellcat debate. The F6F flew 62,240 action sorties from carriers and the F4U flew 6,488 from carriers (9.6 : 1). But the Corsair flew 52,852 sorties from land versus the Hellcat's 1,646 (32.1 : 1). If you take them as a single group, the F6F flew 63,886 action sorties and the F4U flew 59,340. So, the F6F flew about 7 – 8% more action sorties than the F4U, which is about a wash. The relative mix of sorties between carrier and land was due more to the US Navy's delay of carrier acceptance of the F4U than to anything else. It was a matter of where the aircraft were located at the time of the mission. That the F6F scored three times the aerial victories of the F4U is due largely to the fact that the F6F was the standard USN carrier fighter after it was introduced and the Pacific was largely a carrier war for a pretty good chunk of the war. So, the F6F flew in a more "target-rich" environment than the F4U did while having almost 10 times more opportunity to score than the F4U did since most of the Japanese aircraft were on carriers until they were lost.

Doesn't answer some of your questions, but specific answers as to catapult capability to absorb energy might be a bit tough to dig up. On the other hand, our membership here includes people related to WWII pilots from all services. They might know or have access to the data.

 

[RCAFson]

I was just thinking about this very question as I looked at this image of what must be near the limits of what a British carrier can spot on the deck. HMS Formidable in Far East 1944. THE FLEET AIR ARM AT SEA, JULY 1944
QUOTE]

In June 1944, Illustrious ranged 39 aircraft; 15 barracudas and 24 F4Us, with the first 5 being catapulted and the remainder flown off

 

[pinehilljoe]

A good source for aircraft Orders of Battle in the Pacific is Samuel Elliot Morison's series of books. During Operation Iceberg around Okinawa, the typical Essex had 72 fighter (two squadrons of 36) and about 36 TBMs and SB2C (18 each in two squadrons). I scanned the OofB for TF-58, and I think Bennington had the largest AirGroup with 102 aircraft. Hard to believe that many aircraft could be crammed in the hangar and on deck.

(I'm lucky my Mother always encouraged my love of aviation and history, Morison's books were offered by subscription when I was in high school in the late 70s, I have the complete set, still cherished on my bookshelf)

 

[RCAFson]

I was just thinking about this very question as I looked at this image of what must be near the limits of what a British carrier can spot on the deck. HMS Formidable in Far East 1944. THE FLEET AIR ARM AT SEA, JULY 1944

View attachment 582777

They RN had come a long way from small air groups.

Carrier Operations in WWII lists Formidable as carrying 24 x Barracudas and 18 Corsairs in July 1944 for Operation Mascot, so it looks like she has ranged all 18 of the latter and at least 20 Barracudas. In August 1944, Formidable is listed as embarking 24 Barracudas and 30 Corsairs for Operation Goodwood.

 

[Freebird]

In June 1944, Illustrious ranged 39 aircraft; 15 barracudas and 24 F4Us, with the first 5 being catapulted and the remainder flown off

Illustrious class could carry 54-58 aircraft in 1943-1945 and frequently did.
With the removal of the "round-down" from the Illustrious carriers and some deck edge parking they could operate a deck park of about 25 aircraft, in addition to 33 in the hanger.

For Victorious's 1943 operations in the Pacific with Saratoga it was configured to carry 16 Avengers and 42 Wildcat - although only 36 were embarked as there was a shortage at Pearl.
During the operations by the two carriers Victorious operated 60 aircraft - all Widcats - while her FAA Avenger squadron embarked on Saratoga.

ILLUSTRIOUS fleet aircraft carriers (3, 1940 - 1941)

4/1944 Illustrious42 Corsair15 Barracuda---
8/1944 Formidable 30 Corsair 24 Barracuda---
11/1944 Victorious36 Corsair 19 Avenger 2 Walrus
12/1944 Illustrious 36 Corsair 21 Avenger---
3/1945 Formidable - 36 Corsair18 Avenger---
7/1945 Formidable - 36 Corsair, 6 Hellcat 12 Avenger---
8/1945 Victorious- 37 Corsair 16 Avenger 2 Walrus

 

[Admiral Beez]

Illustrious class could carry 54-58 aircraft in 1943-1945 and frequently did.

4/1944 Illustrious42 Corsair15 Barracuda---
8/1944 Formidable 30 Corsair 24 Barracuda---
11/1944 Victorious36 Corsair 19 Avenger 2 Walrus
12/1944 Illustrious 36 Corsair 21 Avenger---
3/1945 Formidable - 36 Corsair18 Avenger---
7/1945 Formidable - 36 Corsair, 6 Hellcat 12 Avenger---
8/1945 Victorious- 37 Corsair 16 Avenger 2 Walrus

I have to give the Illustrious class credit and points for luck, the only class of fleet carrier in service from start to finish of WW2 to never lose a ship in combat, notwithstanding bomb and torpedo hits, collisions, a grounding, Kamikaze strikes, etc. fighting from Norway to Malta, Ceylon and Sumatra. Yorktown and Outrageous classes both lost 2/3 of their number, while pretty much every class of IJN carrier took losses, plus all the one-off RN carriers spare Argus, but the Illustrious class soldiers on.

 

[cherry blossom]

As nobody has said anything about Japanese aircraft carriers, I tried to find out how they limited the aircraft that they carried. I have only looked at the fleet carriers using online sources (if I was feeling rich I could learn more www.christian-schmidt.com/product_info.php?products_id=10545) such as www.combinedfleet.com/kojinshavolume6.pdf or Armoured Aircraft Carriers.
The elevators were generally fairly large especially compared to the RN carriers because many IJN aircraft only had folding wing tips. Soryu had three elevators 16m by 11.5m, 12m by 11.5m, and 10m by 11.5m. Hiryu's three elevators were 16m by 13m, 12m by 13m, and 13m by 11.8m. Shokaku also had three elevators which were 13m long and 16m wide and the other two measured 13 by 12 meters.
The later designs, Taiho and Unryu, went to two roughly pentagonal elevators. Taiho's were 13.6m by 14m (forward) and 14m by 14m (aft) whilst Unryu's were the same sizes but reversed with the forward slightly larger.
The later elevators were stressed to take heavier aircraft with Taiho's taking 7500 kg aircraft. Some of the earlier carriers were only stressed for 4500 kg but I don't know what could be lifted by the Shokaku Class.
The arresters were all Type 4 but not all Type 4 were the same. The first Type 4 could stop a 4-ton aircraft traveling at a speed of 30mps (acceleration 2.0 G's) in less than 40 meters which refers to Soryu's system. The modified Type 4 on Taiho was able to trap 13,200lb aircraft at 78 knots on each of its six forward and eight aft wires (78 knots is 30 mps) but the weight stopped has risen to 6 tons.
Japan never developed a usable catapult but the flight decks were close to the length of the Essex Class, so they probably could have handled the take off of any WW2 carrier aircraft.

 

[Admiral Beez]

The elevators were generally fairly large especially compared to the RN carriers because many IJN aircraft only had folding wing tips. Soryu had three elevators 16m by 11.5m, 12m by 11.5m, and 10m by 11.5m. Hiryu's three elevators were 16m by 13m, 12m by 13m, and 13m by 11.8m. Shokaku also had three elevators which were 13m long and 16m wide and the other two measured 13 by 12 meters.
The later designs, Taiho and Unryu, went to two roughly pentagonal elevators. Taiho's were 13.6m by 14m (forward) and 14m by 14m (aft) whilst Unryu's were the same sizes but reversed with the forward slightly larger.
The later elevators were stressed to take heavier aircraft with Taiho's taking 7500 kg aircraft. Some of the earlier carriers were only stressed for 4500 kg but I don't know what could be lifted by the Shokaku Class.

The most interesting thing to me about IJN lifts are the double deckers that rise above the flight deck, allowing aircraft from both the lower and upper hangars to be moved to the flight deck in one lift rotation. HMS Ark Royal had double decker lifts, but the upper lift did not rise above the flight deck, meaning any aircraft from the lower hangar had to be shuffled onto the upper hangar and then put back onto the lift.

You can see the IJNS Kaga's double decker lift risen above the flight deck here. The IJN must have allowed for the weight of two loaded aircraft on these double lifts.