Questions on Japanese ship mounted seaplanes

[Fatboy Coxy]

Hi all, I have a couple of questions regarding the seaplanes carried on the IJN cruisers and battleships, namely the Nakajima E8N 'Dave', Aichi E13A 'Jake' and Mitsubishi F1M2 'Pete'.

Did they all carry radios, if not, when were they equipped with them.

How easily could they be in radio contact with ships other that their own 'mother' ship, or was their messages relayed through the 'mother' ship?

Regards
Fatboy Coxy

 

[ThomasP]

Hey Fatboy Coxy,

Yes, under any kind of normal circumstances they all carried radios. Long range communication was usually by Morse code (or another form of code) using what is usually called interrupted CW (Continuous Wave, or sometimes Carrier Wave) by radio. By the start of the naval war in the Pacific all of the scout types you mention would have been fitted with radio - after that time the only instances in which they were not fitted would be if none were available (due to supply problems).

As to who the scout aircraft communicated with - that can get a bit complicated. Normally the scouts would communicate with their 'mother' ship, and the message would then be relayed to the appropriate command ships or land based HQs. This was partly due to the scout aircraft crew and the 'mother' ship's communication crew having a well developed working relationship, and partly to keep the workload down in the command ships. However, this dynamic was sometimes changed in order to get the intel directly to the command ships and land based HQs. Since the communication frequencies, codes, and in some circumstances the timing of the transmissions, had to be coordinated/set-up before launch it was usually more effective for the scouts to communicate directly with the 'mother' ship. But, proper coordination could/did allow modification of the normal practice. There were normally also 'contingency' plans, where the scout aircraft would switch to a different frequency if they could not contact their 'mother' ship, hopefully allowing the scout to get the intel to the fleet via another route. On operations there would normally be a standing watch in the radio room for out of the ordinary situations, with the crew monitoring specific frequencies for just such eventualities.

 

[elbmc1969]

Just a note ...

U.S. doctrine at the beginning of the war was for carrier-based scouts (SBDs) to maintain radio silence, return to the carrier, write a note, put it in a lead-filled beanbag, and drop it onto the flight deck!

 

[Jeffrey Ethell Collection]

Fatboy,

In the illustration below showing the observer position in an F1M Pete seaplane, the TOBI Mk.V aircraft radio transmitter and receiver is the blue-gray box marked at No 49. The Morse key-pad with the tapper is the dark rectangular box to the right of the radio set marked No. 47.

It goes without saying that the radio operator wore a headset when transmitting/receiving messages.

There are many Japanese websites with info about these TOBI type aircraft radio sets if you use google.co.jp. The one English website I know of is here:
Ben Nock, Military Wireless Museum

Credit: Maru Mechanic No 20, "IJN Type 0 Observation Seaplane F1M" No. 20, Shio-syobo Co (Publisher) 1980.

James

 

[swampyankee]

One possible benefit to having the scouts communicate with the "mother" ship is that the radio operators on shipboard could learn the observer' "fists," the unique way each person will send code. This would make it more difficult for a third party to spoof communications.

 

[Jeffrey Ethell Collection]

Does anyone have any idea what the range of these HF radio sets would be?

Given that a F1M Pete scout seaplane might go out 400 nautical miles (740 Km) from the "mother" ship. Would that be the safe transmit range?

Range figures for F1M Pete from book, "Japanese Aircraft of the Pacific War" by Rene J. Farncillon, Naval Institute Press, 1995.

James

 

[ThomasP]

I think the F1M 'Pete' only had an operational scout radius of ~150* nm. The E13A 'Jake' was able to scout to a radius of ~350 nm, and the A6M2-N 'Rufe' to a radius of ~450 nm. I can not say as to the specific radio capabilities, but the combination of the altitude of the aircraft when transmitting, the broadcast power and frequency/wave-length of the aircraft radio, the height/length of the ship's receiving antenna, and the sensitivity/gain/SNR of the ship's radio system, would have to allow 'reliable' communication at these ranges.

*[edit: fixed typo for radius of F1M 'Pete' to 150 instead of 250]

 

[Jeffrey Ethell Collection]

Thanks Thomas

I think the F1M 'Pete' only had an operational scout radius of ~150* nm. The E13A 'Jake' was able to scout to a radius of ~350 nm, and the A6M2-N 'Rufe' to a radius of ~450 nm. I can not say as to the specific radio capabilities, but the combination of the altitude of the aircraft when transmitting, the broadcast power and frequency/wave-length of the aircraft radio, the height/length of the ship's receiving antenna, and the sensitivity/gain/SNR of the ship's radio system, would have to allow 'reliable' communication at these ranges.

*[edit: fixed typo for radius of F1M 'Pete' to 150 instead of 250]

I may have misconstrued the 400 NM range of the Pete as distance for one way leg when it is actually TOTAL range of outbound plus return legs. So 200 NM is the radius of action during a search or 150 Nm if there is a 100 Nm sector search triangle. So your 150 NM range is correct.

James

 

[cherry blossom]

There was one famous occasion when radio communication between a Japanese spotter aircraft and its cruisers failed, the Battle of the Komandorski Islands on March 26th, 1943. Quoting from the History of United States Naval Operations in World War II, Vol. VII - Aleutians, by Samuel Eliot Morison on Vice-Admiral Hosogaya's decision to break off the action when he was about to win: "There were several reasons for this decision by the Japanese commander. His fuel supply was low and he wished to be certain of enough to get home. His ammunition was "below the minimum prescribed by doctrine." He was disgusted with the performance of his destroyers. Nobody told him that Salt Lake lay dead in the water because the only Japanese who could see her through the smoke was the pilot of Nachi's spotter plane, who either could not get through to the Admiral with this vital piece of news, or did not try." The Battle of the Komandorski Islands, March 26, 1943

My take is that earlier hits on Nachi had probably caused a loss of communication and that the spotter had either not realised that his signals were not being received or could not signal other ships such as the cruiser Maya.

The spotter seems to have been an Aichi E13A Type 0 Jake as Aichi E13A Type 0 Jake / 72-206 / offers decals for an E13A1 and states "Unit/Location: Heavy Cruiser "Nachi", Battle of the Komandorski Islands, 26.03.1943. Code: White WI-3. Historical occasion: This plane carried out artillery spotting duties during the action. The crew flew on to Attu/Aleutians in the end, crashed at landing but survived to return to Japan via submarine."