Anyone interested in some intellectual exercise?

All three US main class's of CVE were based upon proven merchant/tanker hull design effecting about 17 to 20 knots, Britain created a type of only 13 knots, so yes it can be done.

 

Some of the heavier planes had trouble launching off CVE's especially if they had a full load of fuel and munitions. One reasons the F4F's kept flying off them rather than F6Fs I believe. Since the proposal is I believe to use them mostly for ASW and with older type planes you should be fine.

 

I would also oppose taking tankers away from their duties. The merchant aircraft carrier concept allows them to provide a basic level of air support while operating normally in convoys to and from our petroleum production and refining sites. An elevated flight deck will not impede cargo handling operations on a tanker the way it would on a freighter.

Good point about speed, but as noted it will be addressed by operating appropriate aircraft, including biplanes. If I may skip ahead in the timeline, the Army operated Ki-76s, their equivalent of a Piper Cub or Fiesler Storch, in the ASW role from its carrier Akitsu Maru (though I hope our interservice cooperation will be such that General Nishino and his comrades will not feel compelled to build their own navy!).

The merchant aircraft carrier is distinct from an escort or auxiliary carrier conversion in which the ship ceases to be a cargo ship or whatever. Full conversions should be the fastest available ships so they can operate more capable aircraft. There should be sufficient passenger and similar types in the 20-knot range such as Taiyo or Chuyo.

Turning to escort ships, the best antisubmarine escort is, well, an escort, which can accompany its convoy from departure to destination. We are fortunate that most of our convoy routes should enable this to be done with relatively small ships like the 740-ton kaibokan. British experience has shown that the convoy is actually the most offensive tactic, in that it compels the hostile submarine to make contact with our AS forces.

In the days of sail, there were wooden ships over 300' long, but I'm not aware of modern types over about 180' - anyone? We can use wood for subchasers, minesweepers (which also make good escort ships), etc. but our primary focus both in construction and employment should be on convoy escorts.

 

As we plan to replace many of our 1st line aircraft with better types, we should have a solid pool of sevicable aircraft to use. If neccasary we could instal catapults, it would be cheeper than giving these ships warship hulls and powerplants.

 

All 5 CVE's I listed began as liners, I have no objection to using more liners if available, but do we need any for troop transport? Troops of course could be moved in a standard cargo transport, but do liners offer any special advantages?

Since a CVE could be made from a Cargo hull I have no objection to using these hulls as opposed to 'tanker' hulls.

Let me be clear I am not advocating we take an existing tanker out of service to convert to a CVE, rather that we assign a new build hull as such. I would say that periodicly as existing tankers come into shipyards for overhaul or repair that they be given a flush deck to act as a merchant carrier. This in conjuction with new build tankers assigning a percentage to be completed as merchant carriers. If we can deploy enough hulls with flush decks we may be able to detach CVE's from close protection tasks to a variety of other duties, independent H/K groups , Pilot training, Aircraft Transfer and even support of ground operations at widely scattered island groups.

 

If you use the same design for tanker and CVE hulls you may get some economies of scale. At the very least parts should be easier to come by. The question may be though what is on the critical path. Note the comment I posted below about diesels being a problem for certain patrol boat classes.

 

Can't say about that for certain, since the CVEs also operated the Grumman Avenger. An empty Avenger only weighed one ton less than a loaded Grumman F6F(an empty Avenger weighed about 10,500 lbs. empty & the F6F was about 12,500 lbs. loaded). Of course, the maximum takeoff weight for a F6F was about 15,500 lbs.

However, I believe that the CVEs had problems operating their Avengers in no-wind or little-wind conditions. Also, I believe all, or at least most, CVEs were fitted with catapults to help launching aircraft when the wind was lacking.

 

That may be a little deceptive. The Avenger was heavier, but it also had a much larger wing area leading, I believe, to a slower stall speed. Which is really the relevant thing here.

Carronade:

I believe we are sufficiently supplied with transports that we can give preference to these for full CVE conversions. At this point I think we should carefully consider what roles we intend for auxiliary aircraft carrying vessels and what ships would be best and most economical to perform them. Thus far we have discussed trade protection in the guise of ASW warfare, flight training, and amphibious assault. To this I would add aircraft ferry. Any other suggestions?

We presently have three carriers available that are suitable as auxiliary carriers but not really as front line units. We are using Hosho for training, Taiyo as an aircraft ferry, and Ryujo as a reserve carrier possibly for amphibious assaults. We will shortly also have Hiyo, Junyo, Chuyo, and Ryuho available. We also have several aircraft transports suitable as aircraft ferries to secondary locations. Additionally, I believe the army has already begun conversion of Akitsu Maru. With improved coordination between our two services, if the IJA is willing, we could fit it with arresting wires and provide carrier qualified aircraft and pilots which would give General Nishio a more capable amphibious assault ship.

I believe we will need at least two auxiliary carriers for training. Ryuho can be the second of these, since conversion is already underway.

I think our needs for amphibious assaults should be kept fairly modest, since we don't wish to expand too far lest we create supply problems for ourselves, and our largest assaults are likely to occur before we can have new construction ready in any event, so resources already in conversion will probably suffice for this as well.

Commerce protection is clearly the largest of these. Given the peculiar circumstances of our trade, well beyond the envelope of possible enemy air support but comfortably within our own, I think merchant carriers might actually serve us better than true escort carrier conversions. We are very short of adequate hulls, thanks in part to recent acquisitions for naval auxiliaries. We probably won't need that many airframes for protection of a given convoy, since we don't expect air opposition. A dozen aircraft that can loiter a little distance from our convoy during daylight should be quite effective. If we were able to provide 1-2 MACs per convoy plus an adequate number of ASW escorts I think we would be in quite good shape.

The Prime Minister listed five major routes and five minor. We will probably want convoys operating round the clock on the major routes: say two convoys to a route for at least 10 MACs presently, and other convoys on an as needed basis. 15 total MACs might well be a good start. Perhaps create 5 escort comamnds: two in Japan, one in Formosa, one presently in Indochina (for the SRA), and one at Truk. These commands could then assign MACs and escorts to convoys as needed. We can add or move these "muster points" as we secure control of our intended expansions.

This leaves our full conversions available for assignment as needed. They could be assigned to escort commands if there are shortages. They could be the nucleus of dedicated ASW groups if things get particularly bad in any given area. They can serves as the core of additional amphibious assault groups.

If we decide we need additional full conversions, we might consider Hokoku Maru, Aikoku Maru, and Gokoku Maru. These three ships are former liners presently being used as armed merchant cruisers. All are relatively large and fast and could serve as the basis of ships roughly comparable to the Taiyos.

 

What about using the old CL's 4 I think for either amphibious or other duties.

 

I have much faith in the MAC concept. There are however some concerns for me in using these exclusively for airborne ASW in lieu of CVE's.

So far it is still an unproven concept. It should work, we need it to work, but we cannot say how well it will work.

Because there are no hangers and because we can;t ensure that we can have enough quality mechanics to maintain maintenance we could see a fairly large number of 'Deck Queens' and air frame losses due to aircraft operated below peak preformance.

Since we need Tankers for MAC's it would mean exposing them to convoy routes that perhaps not need so many tankers to actually service some of the convoy destinations.

We know CVE's will work, but untill we try it MAC's are at least something of a gamble. A gamble worth taking I feel, but that does not mean we should not stack the deck in our favor for something this important. If the MAC's work to our expectations we can then retask CVE's already produced to new duties.

 

SP, this is a portion of something else I have been working on and have saved on the computer. I had started assigning classification types and pennant numbers to ships. I was doing this in order to expedite issuing orders and to avoid mistakes with ships with similar names once the game started. I think the classifications I assigned give a proper idea as to what the ship is suitable for. CV is a Fleet Carrier with a sizeable air complement and sufficient speed to operate with the main fleet. CV(a) Auxilliary Carrier, an aircraft carrier with the size and air compliment of a fleet carrier but is unsuited due to speed or other considerations for operations with the main fleet. CVL Light Aircraft Carrier, smaller carrier with sufficient speed to operate with the main fleet, but with a smaller air compliment. CVE Escort Aricraft Carrier, a small carrier with a smaller air compliment and insufficient speed or other considerations that make them unsuitable to operate with the main fleet. Good for utility type jobs such as ASW escort, air support of amphibious operations, etc. CVT-Training Aircraft Carrier. CVS-Seaplane Carrier, ship designed to carry and operate seaplanes. In parentheses the aircraft compliment is listed. Launch and commissioning dates are also listed where applicable. As far as I know, with the exception of the Taiho which was laid down in July this should be all the carriers that are sufficiently along in the pipeline that we have to build them or need to build them to the historical configuration.

CV-1 (reclass CVL1 later CVT-1) Hosho (21)
CV-2 Akagi (72-91M)
CV-3 Kaga (81-90M)
CVL-2 Ryujo (48)
CV-4 Soryu (63-71M)
CV-5 Hiryu (64-73M)
CV-6 Shokaku (72-84M)
CV-7 Zuikaku (72-84M)
CV(a)-8 Junyo (53) (L-26JUN41 C-05MAY42)
CV(a)-9 Hiyo (53) (L-24JUN41 C-31JUL42)
CVS-1 Chitose (24 FP) Conv (30)
CVS-2 Chiyoda (24 FP) Conv (30)
CVL-3 Zuiho (30)
CVL-4 Shoho (30) (C-26JAN42)
CVL-5 Ryuho (31) (C-28NOV42)
CVE-1 Taiyo (27) (C-15SEP41)
CVE-2 Unyo (27) (C-31MAY42)
CVE-3 Chuyo (27) (C-25NOV42)
CVE-4 Kaiyo (24) (C-23NOV43)
CVE-5 Shinyo (33) (C-15DEC43)

 

The US has no CVE's operational until Sept of 1941, and it's doubtful that Japan had any good information on it.

There are in fact no MAC's in the fall 1941, nor any carriers built on cargo ships, nor any CVE's operating ASW, so Japan can't really say "we need that" of something that doesn't exist. The only carrier that was a CVE type was Audacity, but it didn't operate ASW, it carried Martlets and covered the UK - Gibraltar route to protect against Fw200 Condor aircraft.

Unless the Japanese are using "Crystal ball planning" there wouldn't be any precedent for using CVL/CVEs for ASW. Frankly to be more realistic they shouldn't be discussing CVE's or ASW from that type of ship at all. The Japanese never really used CVL's for ASW, they were used for aircraft transport, training as or Aux. carriers. They also never considered converting freighters until 1944, despite the loss of so many carriers in 1942, because they didn't think that the ships would be suitable for operations. Though they did convert passenger liners, they were all capable of at least 20 knots, the first freighter CVE project was the Yamashiro Maru in 1944 World Aircraft Carriers List: Japanese Aircraft Carriers

However it would reasonable for the IJN to make plans to increase carrier hulls, just not for ASW. By the time that 1942 rolls around, they would be capable of using these extra CVL's for ASW work, as it became apparent that there was a need for it.

The Japanese would know about Audacity (467', 15 knts) which would be similar to the MAC in that it had no hanger. However, it operated on the UK -> Gibraltar route, so bringing new aircraft wouldn't be a major problem. Would the Japanese want to risk having a CVE run short of aircraft? The other examples would be the HMS Argus, and the Kaiyo which is undergoing conversion.

Yes, the Japanese are already short of troop transports, and you are considering even larger operations.

Yes, they are faster than freighters, and usually longer

There is one key consideration as LWD mentioned - high performance (especially loaded) aircraft couldn't operate on the small carriers - the British used Swordfish for ASW work off the small carriers, it was slow but it had very minimal requirements as far as deck length and takeoff speed. They also used Marlets. Your loaded aircraft like the Kate or Val may not be able to operate off of a 12 knot short-deck carrier for ASW operartions

 

freebird:

The IJ Army is already in the process of constructing what amounts to a merchant aircraft carrier. (Akitsu Maru was essentially a liner with a flight deck. No arresting gear, so any aircraft launched must either land on an airfield or ditch. Thanks to the capacity to carry both troops and landing craft, some class this the world's first amphibious assault ship.) Additionally, Japan has already converted oilers and tankers into seaplane carriers with plans to make them aircraft carriers if necessary. Notoro was rebuilt as a seaplane tender. Chiyoda was designed as a high speed oiler, completed as a seaplane tender, and rebuilt as a carrier. Even Hosho's design was based on that of an oiler.

Essentially, Japan has come up with the same idea independently. The only real change I'm suggesting to our ongoing MAC construction is adding arresting gear, which we've already done on our full conversion Taiyo. (Which is generally regarded as a CVE even though the U.S. didn't use this classification until . . . 1943? 1944?) I'm using the English term "Merchant Aircraft Carrier" since we all speak English and I don't know the Japanese term. (Assuming they had one. They had one for everything else, so surely they did.)

Also, please note that I suggested using our older biplanes which have recently been relieved of front line duties. We have about 1000 in a few different types: 200 Mitsubishi B2M torpedo bombers, 200 Yokosuka B4Y torpedo bombers (some of which are still operating from Hosho), and nearly 600 Aichi D1A dive bombers, plus a few odds and ends of other sorts. Additionally, some of our monoplane types recently retired from front line service, like the A5M or B5M could also be useful. Since they're fairly light they can operate off shorter decks than one might otherwise expect. (Hosho is still operating A5Ms.)

We have considerably more experience with small aircraft carriers than the allies, since we've experimented with small carriers extensively. This is not at all something Japan could not or indeed did not do.

Honorable Prime Minister:

I do not wish to suggest we make no full conversions. I was assuming we'd go ahead with at least the first three in the Taiyo class and I suggested three other ships which might prove eminently suitable: the Hokaku Maru class ships which are presently serving as auxiliary cruisers.

Further, while I didn't state this, I see no reason our MACs couldn't be from other ships. Tankers may serve better for full conversions because of their fairly open interiors, but troop transports and bulk freighters would also serve adequately for MACs. We should surely take routes into consideration for assignment. On the other hand, is there anyplace in our empire we won't need oil? Further, MACs could be ready fairly quickly since the conversion is quite minimal. That said, I do not mean to suggest that we should forgo CVE conversions in favor of MACs, merely that we might give preference to MAC conversions for convoy escort since it's easier on our resources and should do the job admirably. I think we'll still need CVEs, but maybe not so many.

Mr. Secretary:

I've done something similar for my own record keeping in my miniatures campaigns. The only difference is that I didn't remove the CVLs (or As, if you will) from the main sequence. Thus I arrived at this:

CV(L)-1 Hosho
CV-2 Akagi
CV-3 Kaga
CV-4 Ryujo
CV-5 Soryu
CV-6 Hiryu
CV-7 Shokaku
CV-8 Zuikaku
CVL-9 Zuiho
CVL-10 Shoho
CVE-1 Taiyo

and coming up
CV(A)-11 Junyo
CV(A)-12 Hiyo
CVL-13 Ryuho
CVL-14 Chitose?
CVL-15 Chiyoda?
CVE-2 Unyo
CVE-3 Choyu
CVE-4 Kaiyo?
CVE-5 Shinyo?

and our building program starts to kick in at that point.
CV-16 Unryu
CV-17 Katsuragi
CV-18 Sasuhachi (Shokaku)
CV-19 Akebachi (Shokaku)
CV-20 Koganehachi (Shokaku)
CV-21 Taiho
CV-22 Shinano?
CVE-6 (Hokaku Maru Conv.)
CVE-7 (Hokaku Maru Conv.)
CVE-8 (Hokaku Maru Conv.)
MAC-1
MAC-2
MAC-3
MAC-4
etc.

You'll actually find that the U.S. Navy did the same thing during the war in their recognition guides. (And to the Royal Navy as well. Oh the indignity! The UK uses sensible measurements. The U.S. uses sensible hull numbers.)

 

SP, sorry for the mis-understanding. My thoughts echo yours as well as for the 'innovation' aspect of CVE's and MAC's. If we take freebirds arguement to its logical conclusion, we would still be using bronze swords and spears. Germany's attempt in both world wars to sever Britains sea communications would be present to Japan and could and did, with some lower ranking officers, stimulate innovative thinking.

 

Well it's not really a MAC.
If you consider a CVE to be a converted freighter, a MAC to be a minimal CVE on a still functioning freighter.
A converted liner would be a CVL or "Auxilliary carrier" intended as transport, training or such.

I don't think you are correct on that.

Chitose/Chindoya were purpose built oilers/seaplane tenders that were planned to convert, which is why they were capable of 29 knots.
Notoro was a tanker converted to a Seaplane tender, but was considered too slow to be a carrier.

Well no they didn't, because as mentioned, they didn't plan to convert slower freighters or use carriers for ASW until late in the war

I think "MAC" is the wrong term, they termed the Taiyo as "Auxilliary Carrier".

Do you have a reference for the arresting gear? Because I believe that it did not.

Why would the Japanese want to operate older, obsolete aircraft? If they expected air opposition why wouldn't they operate modern aircraft off of the CVL's (Aux carriers) like Shoho, Ryuho, Zuiho etc

I guess that depends on what your idea of "small" is, but of carriers under 500' in the fall of 1941, only the British operated them, the HMS Audacity & HMS Archer. Japan's only carrier under ~590' was the Hosho at 541'. The Taiyo's were about 590', the Akitsu Maru (completed Jan 42) was about 470', but was not intended to operate aircraft, it was only planned to use it as an aircraft transport or a fly-off "assault ship.

It's difficult to try to be realistic in planning this kind of excercise without relying on post-1941 knowledge, so you just have to be careful to consider what they could have known at the time, so obviously planning to design SAMs, radioactive fallout shelters & jet engines is obviously out.


Don't misunderstand what I'm saying, there's nothing wrong with planning smaller or auxilliary carriers.
What I am saying is that planning to use carriers as ASW or planning MACs (slow freighters) was not something that was known to the Japanese, or even the Allies at the time, and is jumping the gun on what was only figured out later.

*The Japanese didn't have any carriers slower than 20 knots, or shorter than 575' until 1943, excpt the Akitsu Maru, and this ship was planned to use as aircrat transport, and wasn't expected to land the aircraft.

The Allies did use 490' CVE's (Avenger, Bogue etc), but of course they also had a catapult

 

Logcal conclusion or Reductio ad absurdum?
What I'm saying (and what USMC had mentioned earlier) was that the excercise should try to use what information Japan had at the time, not what we've learned in the 70 years since.

If you are talking about "CVE"s based on small liners (which they did use) for auxiliary operations, (which they did plan) that's not unreasonable. But using carriers for ASW (which had never been tried and wasn't known or used by the Japanese) isn't.
It seems like you are taking 1944 knowledge (about the sub danger & CVE's for ASW) and bringing that back into 1941.

It's also not clear that small, slow freighter based CVE's would have been possible without catapults, or why the Japanese would want to use old obsolete biplanes to intercept modern Allied aircraft attacking the convoys?

Do you know what is the minimum speed & deck length to launch a zero?

 

We are employing something of a circular logic here, If Japan can not think of using CVB's for ASW then how can the Allies first? They would need some mythical race to first come up with the idea, then they too would need someone esle and so on.

Japan's needs would closely resemble those of Britain, the need to protect long seaborne convoy routes. For nearly 2 and a half years they have watched Germany's efforts to sever this line of communication and could reasonably infer the value of aircraft in protecting such routes. That need would and could stimulate some new thinking. Forgive me but it is alittle arrogent to hold the position that any group of people simply are not clever enough to come up with an idea first or even at the same time of the western 'good guys'.

It would be a better arguement that Japan was too arrogant to spend the time and effort we are employing. But then arrogence is not solely Japanese failing, Adm. King had the expierence of WWI and the first 2 years of this war and yet he Ignored the advise and reccomendations of his eastern seabord commander in the matter of convoy's, escorts and aircraft. Scores of ships were lost to Operation Drumbeat before he was in effect ordered by FDR to get his S%$t together and make available the assets and form the convoys.

In the end this is a what if, We are not propossing wonder weapons or geneticly engineered super soldiers, merely using what slender resources Japan has at hand. Slow merchantmen and biplane rejects are about as low tech as we can go.

 

why the Japanese would want to use old obsolete biplanes to intercept modern Allied aircraft attacking the convoys?

No one's suggesting that; unless the war goes very badly for Japan, much of her sea lines of communication including the critical ones between the home islands and the Southern Resource Area will be well beyond the range of Allied air attack, or even reconnaissance, but will still need to be protected against submarines.

Whatever positions we take, let's start by being clear on the terms we're using and what they mean. A "merchant aircraft carrier" is distinctly different from an "escort" or even "auxiliary" carrier. It's basically a merchant ship doing its normal duty, but carrying a few small aircraft to enhance a convoy's antisubmarine defense. It could even be argued that a dedicated escort carrier with say 20 planes is more capability than needed.

Information available at the time is a valid point, but the object of this exercise is to consider what Japan might have done differently or better - after all, we already know what happens if they apply their historical doctrine and knowledge unchanged Lack of attention to logistics and trade protection is a widely recognized flaw in Japanese strategy. The danger from submarines and the value of convoy and air protection were not unknown in 1941.

 

Pretty good.
Although I wonder how they might "reasonably infer" that they needed biplanes or slow carriers?
The Germans report that the primary danger is from long range bomber aircraft, not carrier aircraft.
Before Dec 7, 1941 no U-boats have been sunk by carrier aircraft (that I can find) The only U-boat sunk by a Swordfish during that time was U-64, sunk while at anchor in Norway by a Swordfish launched from Warspite.
Could the Japanese infer that they needed more battleships?

I'm still skeptical on the concept, but before the navy started to invest huge time & resources into the project they'd certainly want to test the theory out.
Before Dec 1941, the danger to U-boats was primarily surface escorts (corvettes & sloops etc), followed by long range maritime search aircraft - Catalinas, Sunderlands, Whitleys, Hudsons etc.

The Japanese would likely get the most "bang for the buck" by investing in more surface escorts, and establishing & training dedicated ASW squadrons.
As far as I know, they don't have any? There are well trained torpedo-armed anti-ship Nell & Betty squadrons, but not ASW depth-charge armed ones.
The problem with using merchant hulls (as opposed to liners) is that you are making a huge gamble if this untested theory fails, as the slow, small CVE won't have many other uses except perhaps as another aircraft transport.
Remember, the main difference is that all the small US CVE's had catapults while the Japanese didn't

The best plan (IMO) would be for the IJN to commission some tests, with various types of aircraft in the ASW role before you commit to any project. Put some Japanese subs out and see if the aircraft can find them, and make a successful attack (with dummy bombs obviously)
They will probably find that carrier aircraft are not that effective at ASW, compared to other less costly options.

No, it was mainly due to trial & error, because of the heavy losses. As some methods were not too effective, others were tried

 

What about using the old CL's 4 I think for either amphibious or other duties.

I was thinking of Tatsuta and Tenryu for gunfire support, possibly as flagships for small amphibious operations - maybe Yubari also although she has more potential combat value either as is or with an AA conversion - is that what you had in mind? Or were you thinking of modifying them as something like fast transports? Pretty soon we'll be converting everything in the fleet to something else!

I'm not in favor of developing another destroyer type to serve as a leader. Not counting the little ones above, we have fourteen existing light cruisers plus four under construction (and Sakawa if we proceed with her in 1942), more than enough for the destroyer squadrons we operate or can expect to operate. As noted earlier, AA improvements are not inconsistent with the destroyer leader role.

We've discussed using AA cruisers with the carrier force, not a bad idea in itself; but if we then have to design and build new destroyer leaders to take their place, I think we're making things way too complicated. In that case it would be easier to just build more Akizukis.

SP, I generally agree with your thoughts. Hopefully the game system will give us an idea how many carriers, or how much of their time, is needed to train the numbers of pilots and aircrew we need; until then your estimates seem reasonable. I'm not quite as eager as some to relegate Ryujo to secondary duties, but we'll see what the needs are.

Belasar-sama makes a good point that the merchant aircraft carrier concept is unproved, and as freebird mentions, there are no such things yet in service anywhere. While we have evidence of the potential of submarines from both history and current events, we don't know how our enemies will employ their subs or how effective they will be. It's an intriguing idea, but perhaps we should start with just a few conversions.

Since we need Tankers for MAC's it would mean exposing them to convoy routes that perhaps not need so many tankers to actually service some of the convoy destinations.

I respectfully suggest that the MAC concept is to use ships on their normal routes, as an economical means of providing air defense. If we have to send a ship somewhere it would not otherwise go, just to provide air cover, that's when we use a dedicated aircraft carrier.

I'm not enamored of armed merchant cruisers, so I agree they might be candidates for carrier conversions if needed, or for reverting to their designed passenger-cargo transport role.

One further comment on conversions, I would like to avoid any which require total replacement of a ship's engines. If we truly need a ship of XX knots, and don't have any suitable hulls available, better to invest in new construction.