Question on HMS Repulse

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Fatboy Coxy
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Question on HMS Repulse

Post by Fatboy Coxy » Thu Jul 19, 2018 5:50 pm

One of the major what ifs about Force Z is about the radar on HMS Prince of Wales being faulty, and as a consequence they didn’t detect IJN Chokai on the evening 9 December, when a Betty dropped a flare over her.

However, HMS Repulse had radar as well, and I have never read anywhere that hers were faulty. She had a type 284 surface gunnery set installed in Rosyth mid July 41, whilst a type 286P air warning set was installed on the passage to Freetown, August 41

Do we know if these sets were working Ok, or suffered due to the heat and humidity like HMS PoW’s. Did other ships also suffer similar radar problems in the Far East.

I have read that Phillips was maintaining radio silence, and that this may have included the radars being switched off, in the belief they could be detected while on. If so it would explain while Repulse didn’t pick up Chokai.

The other possibility is the closest distance the ships ever got has been estimated at 15 miles, which might be the extreme range of the 284 at that time. If we say this was 20 miles, then we can safely say it wouldn’t pick up Chokai.

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Dave Saxton
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Re: Question on HMS Repulse

Post by Dave Saxton » Fri Jul 20, 2018 2:00 am

The 284 as a gunnery radar mounted to the main director would likely be kept switched off until a surface combat threat materialized. It required that it be rested at intervals when in operation, so there was little incentive to leave it switched on all the time, especially if spare vacuum tubes and other spare parts may not be readily available in the Far East. If it was switched on, Type 284 had a reliable range to a cruiser of less than 20,000 yards in 1941.

Type 286P had a maximum range to a large surface ship of only about 11,000 yards.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Question on HMS Repulse

Post by Kev D » Sun Jul 22, 2018 7:37 am

Fatboy Coxy wrote:
Thu Jul 19, 2018 5:50 pm
One of the major what ifs about Force Z is about the radar on HMS Prince of Wales being faulty, and as a consequence they didn’t detect IJN Chokai on the evening 9 December, when a Betty dropped a flare over her........................The other possibility is the closest distance the ships ever got has been estimated at 15 miles, which might be the extreme range of the 284 at that time. If we say this was 20 miles, then we can safely say it wouldn’t pick up Chokai.
Just wondering where "....the closest distance the ships ever got has been estimated at 15 miles" came from? I would be I interested to know if from a report or a book. Hopefully not because of the bogus flare sighting alluded to being reported by HMS Electra; as that has been refuted by both Commander - I think at the time? -T J Cain in Electra, and - if I am not mistaken re who - Captain Bell in Prince of Wales bridge.
We are off to look for trouble. I expect we shall find it.” Capt. Tennant. HMS Repulse. Dec. 8 1941

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Re: Question on HMS Repulse

Post by HMSVF » Sun Jul 22, 2018 5:47 pm

Seem to remember "Battleship" By Middlebrook & Mahoney mentioning something similar...

Fatboy Coxy
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Re: Question on HMS Repulse

Post by Fatboy Coxy » Sun Jul 22, 2018 7:08 pm

Dave Saxton wrote:
Fri Jul 20, 2018 2:00 am
The 284 as a gunnery radar mounted to the main director would likely be kept switched off until a surface combat threat materialized. It required that it be rested at intervals when in operation, so there was little incentive to leave it switched on all the time, especially if spare vacuum tubes and other spare parts may not be readily available in the Far East. If it was switched on, Type 284 had a reliable range to a cruiser of less than 20,000 yards in 1941.

Type 286P had a maximum range to a large surface ship of only about 11,000 yards.
Thanks Dave, I have also read another of your posts about British Radar, very informative, thank you.

I’ve read the type 284 took about 45 minutes to warm up, presumably this means to achieve maximum reliability of contact detection. If so it would lend weight to a suggestion that most radar sets were employed as a tactical weapon, when a threat was expected. Given the need to preserve the sets, along with the suggestion that active radar could give away your position, Phillips probably had all the sets switched off. The only one that might have been employed would have been the Type 281 on HMS PoW, which we know was faulty.

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Re: Question on HMS Repulse

Post by dunmunro » Sun Jul 22, 2018 11:21 pm

From:
B.R. 1736 (8)/1955.
NAVAL STAFF HISTORY
SECOND WORLD WAR
Battle Summary No. 14 (revised)

LOSS OF H.M. SHIPS PRINCE OF WALES AND REPULSE
10th December, 1941

At 0620, 9th, an aircraft was reported by the Vampire; it was sighted for a few seconds by one look-out only, and as the weather was favourable for evasion, with frequent rain squalls and low cloud, the squadron held its course to the northward. Between 1700 and 1830, however, the weather cleared and three Japanese naval reconnaissance aircraft were sighted from the Prince of Wales4 at 1740. This meant that all hopes of surprise had been lost, and a heavy scale of air attack off Singora had to be anticipated. Under these circumstances the Commander-in-Chief decided that the risk was unjustifiable and that he must give up his project. At 1825 the Tenedos, which was running short of fuel, was detached to Singapore, with orders to transmit a signal to the Chief-of-Staff at 0800, 10th, requesting destroyers to meet Force "Z" off the Anambas at dawn, 11th December.5 The remainder of the squadron altered course to the north-westward at 1850 and to the westward for Singora at 1930 (presumably to mislead the shadowers). They were then only about 15 miles to the southward of Admiral Kurita's four heavy cruisers which at that moment altered from a southerly to a north-easterly course to join their battlefleet. (See Sec. 11.) Completely unaware of this narrowly missed contact,6 Admiral Phillips continued to the westward till 2015, when he finally abandoned the operation and reluctantly shaped course at high speed for Singapore. A spontaneous signal from the Captain of the Repulse, showing that he appreciated the difficulty of this decision and agreed with it, cheered the Commander-in-Chief at this disappointing moment.

http://www.ibiblio.org/hyperwar/UN/UK/R ... html#sec10

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Dave Saxton
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Re: Question on HMS Repulse

Post by Dave Saxton » Tue Jul 24, 2018 4:12 pm

Fatboy Coxy wrote:
Sun Jul 22, 2018 7:08 pm


Thanks Dave, I have also read another of your posts about British Radar, very informative, thank you.

I’ve read the type 284 took about 45 minutes to warm up, presumably this means to achieve maximum reliability of contact detection. If so it would lend weight to a suggestion that most radar sets were employed as a tactical weapon, when a threat was expected. Given the need to preserve the sets, along with the suggestion that active radar could give away your position, Phillips probably had all the sets switched off. The only one that might have been employed would have been the Type 281 on HMS PoW, which we know was faulty.

The reason Type 284 took so long to warm up is because the transmitting tubes were anode modulated. A thyratron (a gas filled tube) was used to deliver a high voltage pulse to the anodes of transmitting tubes. First the thyratron had to be warmed up and then the transmitting tube took time before it would begin to pass electrons. Most radars that used transmitting triodes have the pulse delivered to the control grid and these do not require a long warm up period. However, anode modulation is a way of producing much more output power. German documents warn that their Hohentwiel radar, which was also anode modulated, required at least ten minutes before it would be useful.

Magnetron powered radars also require a long warm up period, usually much longer than anode modulated radars. With a magnetron the pulse must be delivered to the cathode so they can not be used right away. A magnetron radar requires a long period to settle in, and may also require tuning by the operators, before it can provide accurate data. With a magnetron powered radar if the electrical power is momentarily lost it will be as much as 45 minutes before it will deliver reliable data again.

The former radar operator on POW, Rear Admiral Paddon, mentioned that the Type 281 was usually shut down at dusk aboard the Prince of Wales. It was shut down at dusk on Dec 9th. Type 281 was meters wavelength radar primarily used for air warning. Apparently they thought enemy air operations at night unlikely.

The important radar on Prince of Wales to your question was the 10cm Type 273 Surface warning radar. This we know was non operational by the time they arrived a Singapore, and they had tried mightily to get it working before Force Z sailed, calling in RAF technicians. It may have been able to pickup IJN cruisers at 15 miles had it been working. In tests it was capable of tracking a battleship to 34,000 yards in the Fall of 1941.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Question on HMS Repulse

Post by Kev D » Wed Jul 25, 2018 7:48 am

dunmunro wrote:
Sun Jul 22, 2018 11:21 pm
From:
B.R. 1736 (8)/1955.
NAVAL STAFF HISTORY
SECOND WORLD WAR
Battle Summary No. 14 (revised)
LOSS OF H.M. SHIPS PRINCE OF WALES AND REPULSE
10th December, 1941
Thanks for posting that Duncan. So, upon reading Section 11 of said report, basically post war from the Japanese sides recorded positioning as it were, in relation to Force Z's position at the time of the turn-away. Makes sense.
We are off to look for trouble. I expect we shall find it.” Capt. Tennant. HMS Repulse. Dec. 8 1941

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Re: Question on HMS Repulse

Post by Fatboy Coxy » Wed Jul 25, 2018 9:31 pm

Regarding the estimated distance of the flare, and thereby IJN Chokai to Force Z, the majority of web sites I peruse quote a distance of 5 miles from HMS Electra. I have a couple of problems with this.

I’m taking an educated guess that the bridge of the Electra might be 40 feet above sea level, possibly more. This would give them a horizon of just under 8 miles. If a flare was dropped above a ship 5 miles away, I’d expect the Electra to see the ship as well as the flare. However, if dropped 15 miles away, the ship would be well hidden over the horizon, but a flare dropped even as low as 200 feet above it would be visible to Electra.

The other problem I have is the flare was dropped by an aircraft circling overhead, looking for Force Z, and as the flare came down at least three torpedo bombers were positioning themselves to make an attack. Again, I would think at 5 miles, one/some of the aircraft might be heard by Electra as they position themselves around Chokai, but 15 miles away would give them enough distance not to be heard

However, these suggestions of mine have to be tempered by the fact that this is after dark, in monsoon season, amid numerous rain squalls and with the wind whistling past the ship, a lookout on the wing of a ship might be forgiven for not seeing or hearing anything

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Re: Question on HMS Repulse

Post by Kev D » Thu Jul 26, 2018 9:12 am

As the saying goes Fatboy Coxy, you are chasing windmills. As stated in a previous above post of mine, there never was a flare sighted by Electra, nor any such sighting past on to HMS Prince of Wales (participants on the scene confirm this), although this is by no means the same as saying there was no flare dropped, as there was, just not sighed by Force Z, so not the reason for the 'turn-away'. It's what's known in some circles as a 'phurphy', i.e. written somewhere and then taken as gospel by other authors, etc. (except those that were there) down though the ages.

As opposed to websites with second hand accounts, suggest you read T J Cain's book entitled HMS Electra, and Arthur Mader's 'Old Friends, New Enemies' where he interviews Capt Bell from PoW for first hand accounts of said flare 'report'.

Also please read sections 10 and 11 of the Naval Staff History report Duncan (Dunmunro) posted above, where there is also no mention of a sighted flare.

http://www.ibiblio.org/hyperwar/UN/UK/R ... html#sec10
We are off to look for trouble. I expect we shall find it.” Capt. Tennant. HMS Repulse. Dec. 8 1941

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Re: Question on HMS Repulse

Post by Fatboy Coxy » Tue Jul 31, 2018 8:36 pm

Kev D wrote:
Thu Jul 26, 2018 9:12 am
As the saying goes Fatboy Coxy, you are chasing windmills. As stated in a previous above post of mine, there never was a flare sighted by Electra, nor any such sighting past on to HMS Prince of Wales (participants on the scene confirm this), although this is by no means the same as saying there was no flare dropped, as there was, just not sighed by Force Z, so not the reason for the 'turn-away'. It's what's known in some circles as a 'phurphy', i.e. written somewhere and then taken as gospel by other authors, etc. (except those that were there) down though the ages.

As opposed to websites with second hand accounts, suggest you read T J Cain's book entitled HMS Electra, and Arthur Mader's 'Old Friends, New Enemies' where he interviews Capt Bell from PoW for first hand accounts of said flare 'report'.

Also please read sections 10 and 11 of the Naval Staff History report Duncan (Dunmunro) posted above, where there is also no mention of a sighted flare.

http://www.ibiblio.org/hyperwar/UN/UK/R ... html#sec10
Thanks Kev, I was, wasn't I.

You made me look back, and in any official history's, reports etc I read, there is no Electra sighting.

Did my musings about a sighting at 5 miles make any sense to you?

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Re: Question on HMS Repulse

Post by Kev D » Mon Aug 06, 2018 7:29 am

Pardon delay in reply Coxy, but have been on road traveling on business this past week.

Anyway I think it more like 15 miles if this excerpt below from the post war (1955 IIRC) report Duncan posted is correct (that is, it was written taking into account, with the benefit of hindsight, both Brit and IJN positions at the time, so don't really doubt it).

"At 1825 the Tenedos, which was running short of fuel, was detached to Singapore, with orders to transmit a signal to the Chief-of-Staff at 0800, 10th, requesting destroyers to meet Force "Z" off the Anambas at dawn, 11th December.5 The remainder of the squadron altered course to the north-westward at 1850 and to the westward for Singora at 1930 (presumably to mislead the shadowers). They were then only about 15 miles to the southward of Admiral Kurita's four heavy cruisers which at that moment altered from a southerly to a north-easterly course to join their battlefleet. (See Sec. 11.)"
We are off to look for trouble. I expect we shall find it.” Capt. Tennant. HMS Repulse. Dec. 8 1941

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