RE: An error in IJN CV capacities? (Full Version)

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JWE -> RE: An error in IJN CV capacities? (11/15/2010 4:44:53 PM)

Interesting perspective, Mr. Palmer. Sent you a pm.

Ciao. John



Gilbert -> RE: An error in IJN CV capacities? (11/15/2010 6:08:16 PM)




quote:

ORIGINAL: spence

quote:

Incidentally, I think the plan in Shattered Sword is showing D3A carrier bombers rather than A6M's. The obvious place to strike below the Zeroes is the forward end, given that they will normally go to the front of the flight deck spot because of their short take-off run.


They are not D3As since the Vals did not have folding wings. Folding wings were inherently weaker wings and dive bombers needed every bit of the strength of a one-piece wing in order to withstand the G forces of pullout (that is; in order to make more than one dive per airframe [:D]).
The Ryujo and other CVLs never carried D3As because they were much larger to accommodate in the hangar and on the elevator because of their non-folding wings.



The aircraft with the folding wingtips were A6M2s. The wingtips were removed in later models. The ones with the folding wings were B5N1s or B5N2s.



The Val had folding wings see drawing below

Gilbert



[image]local://upfiles/32531/79C3E380FA7143A9A108BC2BDEBEEFD3.jpg[/image]



Local Yokel -> RE: An error in IJN CV capacities? (11/15/2010 6:38:37 PM)


quote:

ORIGINAL: spence

quote:

Incidentally, I think the plan in Shattered Sword is showing D3A carrier bombers rather than A6M's. The obvious place to strike below the Zeroes is the forward end, given that they will normally go to the front of the flight deck spot because of their short take-off run.


They are not D3As since the Vals did not have folding wings. Folding wings were inherently weaker wings and dive bombers needed every bit of the strength of a one-piece wing in order to withstand the G forces of pullout (that is; in order to make more than one dive per airframe [:D]).

The Ryujo and other CVLs never carried D3As because they were much larger to accommodate in the hangar and on the elevator because of their non-folding wings.



That had me worried - I thought I knew my Japanese carrier aircraft. Fortunately Parshall and Tully come to my rescue[8D]. From p.120 of Shattered Sword:

'Because of the placement of the Type 99's control surfaces and dive brakes, not to mention its need for structural strength, Aichi's designers had decided not to place a folding mechanism too near the center of the wing. Instead, the Type 99's wings folded very near the tips, making it difficult to stow, tricky to maneuver through tight spaces, and a hog of precious parking "real estate."'

If you look closely at the aircraft with folded wingtips in SS Figure 7-1, you can just make out the tips of the wheel spats peeping out below the wings. But those elliptical wings are a giveaway in any case.



herwin -> RE: An error in IJN CV capacities? (11/15/2010 7:13:09 PM)

What would an A6M2 look like on the same scale?



Local Yokel -> RE: An error in IJN CV capacities? (11/15/2010 7:47:33 PM)

I've just run a 1:76 scale rule over my 1:72 plans of a Model 21 Zero and D3A1 and D3A2 variants of the Type 99. It would tax my tired brain too much to convert the result to an accurate dimension, but, interestingly, the D3A2 with tips folded appears to have the same span as the Model 21, also with tips folded. This must be coincidental because the D3A1 wing appears to be hinged further outboard, thus giving it a slightly larger span with tips folded than the other two aircraft mentioned. At first I thought the coincidence of spans might have been dictated by something like size of lift well, but since the earlier D3A1 has a bigger span with tips folded and therefore requires a bigger well I don't think that can be the case.

The real dimensional difference lies in the length: both variants of D3A are at or close to 10.2 metres in length, whilst the Model 21 comes in appreciably smaller at 9.05 metres. I estimate the D3A1 to have a span of about 12.4 metres between wingtip hinge points, so it's a bit bigger (but not that much) than the Zero in all plan axes. Perhaps Parshall and Tully make too much of it being a space hog.



herwin -> RE: An error in IJN CV capacities? (11/15/2010 8:22:52 PM)


quote:

ORIGINAL: Local Yokel

I've just run a 1:76 scale rule over my 1:72 plans of a Model 21 Zero and D3A1 and D3A2 variants of the Type 99. It would tax my tired brain too much to convert the result to an accurate dimension, but, interestingly, the D3A2 with tips folded appears to have the same span as the Model 21, also with tips folded. This must be coincidental because the D3A1 wing appears to be hinged further outboard, thus giving it a slightly larger span with tips folded than the other two aircraft mentioned. At first I thought the coincidence of spans might have been dictated by something like size of lift well, but since the earlier D3A1 has a bigger span with tips folded and therefore requires a bigger well I don't think that can be the case.

The real dimensional difference lies in the length: both variants of D3A are at or close to 10.2 metres in length, whilst the Model 21 comes in appreciably smaller at 9.05 metres. I estimate the D3A1 to have a span of about 12.4 metres between wingtip hinge points, so it's a bit bigger (but not that much) than the Zero in all plan axes. Perhaps Parshall and Tully make too much of it being a space hog.


Well, the analysis seems to hold up--750 square feet for a Japanese carrier aircraft, with an added 10-20% more Zeros if you squeeze them in. 64x750 square feet of aircraft can live in the Hiryu's hangar. However, the Kaga is quoted at 108,240 square feet and 5,568 square feet, and the Akagi with 93,000 square feet for the upper and middle level hangars combined, and 8,515 square feet for the lower level hangar. Subtract 18000 square feet from the Kaga's upper hangars, and you get 90000 square feet for planes--120 or so! The Akagi comes in at 100! I don't trust those figures...

Suppose the quoted figures don't include elevators, and not all the area is usable. Does it work then?



Feltan -> RE: An error in IJN CV capacities? (11/15/2010 9:02:36 PM)

herwin,

Don't you need to account for, hmmmm, looking for a term here: hallways, alleyways, paths, etc. What happens if the plane in the very back row pops an oil leak and you need to bring it forward for maintenance? I'd expect a pathway to get planes in the back out of the crowd. My expectation is not definitive, but certainly not every sq ft of real estate could be used for plane storage.

Regards,
Feltan



herwin -> RE: An error in IJN CV capacities? (11/15/2010 11:59:36 PM)


quote:

ORIGINAL: Feltan

herwin,

Don't you need to account for, hmmmm, looking for a term here: hallways, alleyways, paths, etc. What happens if the plane in the very back row pops an oil leak and you need to bring it forward for maintenance? I'd expect a pathway to get planes in the back out of the crowd. My expectation is not definitive, but certainly not every sq ft of real estate could be used for plane storage.

Regards,
Feltan


As close as they could. Look at that figure in Shattered Sword.



DivePac88 -> RE: An error in IJN CV capacities? (11/16/2010 12:44:24 AM)

I think that when you are working-out the airgroup capacity of the Japanese carriers, you also have to take into account the structure of their carrier air squadrons. I know that on an administration level, the Japanese carrier air squadrons had to sizings. The standard squadron size was 18 operational aircraft, with 3 dismantled spare aircraft. Then there was the 'oversize' squadron of 27 operational aircraft, also with 3 dismantled spare aircraft.

I also think that a lot of the confusion arround the Japanese carrier aircraft capacity, is the inability of their air-industry to supply sufficient numbers of aircraft. So then you would be looking at an airgroup on AKAGI/KAGA of 27+27+27=91 operational airframes, and 9 spare airframe. HIRYU of 27+27+18=72 operational + 9 spare, and SORYU 27+18+18=63 operational + 9 spare.




Pascal_slith -> RE: An error in IJN CV capacities? (11/16/2010 1:09:39 AM)

For illustrations, including line drawings and interior drawings, I've gone and bought some Japanese sources.

Check this page at Amazon (I use the Google translate button often on these).

http://www.amazon.co.jp/%E6%97%A5%E6%9C%AC%E3%81%AE%E8%88%AA%E7%A9%BA%E6%AF%8D%E8%89%A6%E3%83%91%E3%83%BC%E3%83%95%E3%82%A7%E3%82%AF%E3%83%88%E3%82%AC%E3%82%A4%E3%83%89-%E6%AD%B4%E5%8F%B2%E7%BE%A4%E5%83%8F%E3%82%B7%E3%83%AA%E3%83%BC%E3%82%BA/dp/4056030553/ref=pd_sim_b_6

You'd be surprised the wealth of detail you can find sometimes. I have a few people around me that can speak and read Japanese, so I can get help with some of the text. That is the best method to get some superficial translation at times.



Local Yokel -> RE: An error in IJN CV capacities? (11/16/2010 2:02:59 AM)

Harry – I too wondered about those acreage figures. However, if I’ve read Friedman aright, the Yorktowns had a hangar area of 56,640 square feet, so the P and T figures seem to be of the correct order of magnitude, given a double deck hangar over Yorktown’s single level.

Divepac – I agree. This is why 27 X 27 X 27 = 81 looks right to me for Kaga and Akagi. Possibly this suggests a 27 X 27 X 18 = 72 size hikokitai for the Shokakus – player to arrange which aircraft type is restricted to 2 rather than 3 chutai. But they may well have had sufficient space to accommodate the ‘big wing’ of 81, had the necessary aircraft and crews been available.

This is why you are also right to note the distorting effect historical airframe shortages may have upon any assessment of the potential capacity of the big carriers. Some years ago Mark Horan posted this on the Warships1 board:

“In the summer of 1942, all the fleet carriers but Kaga (63 [18-18-27]) were limited to an airgroup of 54 [18+18+18]. That was all Hiryu and Soryu could stuff in anyway. For the other three, even with the light losses suffered in the war to date, there was a severe shortage of all types of CV based aircraft and there were no replacements to fill out the Shokakus with the additional planes (18) they could carry.”

As well as being an interesting comment on Hiryu’s and Soryu’s capacity, this is a telling indicator of the straits to which the Japanese were reduced. However, such historical shortages are no basis for reducing the size of airgroup a carrier is capable of embarking, provided the player manages to produce the airframes and crew required to fill the group to the carrier’s capacity.

(Just noticed that Mark H is saying, in effect, that the Shokakus had capacity for only 72 rather than 81 operational aircraft)

Your post also addresses the issue of reserves, and I agree that a 3-plane reserve of each type embarked should be capable of being accommodated – that would call for Kaga and Akagi’s capacity being lifted to 90: 81 operational + 9 spare.

Whether reserves should count against the carrier’s maximum capacity is another question, but the same principle should be applied to both sides. Is it appropriate to allow the 15% ‘overstack’ capability to lift total aircraft embarked on any 1942 carrier to 103 (90 + 15%)?

On D3A1 wingspan, I’ve seen it reported that the span between wingtip hinges was only 10.932 metres rather than the 12.4 metres I posted. That’s quite a significant difference, so my earlier figure should be treated with suitable caution.



ChezDaJez -> RE: An error in IJN CV capacities? (11/16/2010 5:34:51 AM)


quote:

ORIGINAL: herwin

What would an A6M2 look like on the same scale?



An A6M21 had an unfolded wingspan of 39'4" and uolded of 36'1".
A D3A1 had an unfolded wingspan of 47'7". Was unable to find the length of the folding wingtips but drawings seem to indicate about 3' each.

Chez



Pascal_slith -> RE: An error in IJN CV capacities? (11/16/2010 6:34:55 AM)


quote:

ORIGINAL: ChezDaJez


quote:

ORIGINAL: herwin

What would an A6M2 look like on the same scale?



An A6M21 had an unfolded wingspan of 39'4" and uolded of 36'1".
A D3A1 had an unfolded wingspan of 47'7". Was unable to find the length of the folding wingtips but drawings seem to indicate about 3' each.

Chez


Here's a diagram of the Val showing the folding wingtips.

[image]local://upfiles/9843/59F486B1350B4F13AE979F4594C5C4C8.jpg[/image]



herwin -> RE: An error in IJN CV capacities? (11/16/2010 10:01:24 AM)

Many of my sources are out on loan, so I'm working partly on memory. I believe the large US carriers had room in the hangar rafters for spares. The attack aircraft were on the order of the same spot size as the Japanese (750 sq ft). The folding-wing fighters were about 450-500 square feet. It looks like the basic air group (18+18+18+15+1 = 70) could fit downstairs on a Yorktown.



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