RN carrier homing beacon

[fastmongrel]

I found this article and thought you guys might be interested. http://www.nonstopsystems.com/radio/article-part3a-1947-Quinn.pdf

If you are interested in naval aviation and ever wondered what the lighthouse shaped thing on a RN WWII carrier was (top of mainmast in this pic of HMS Ark Royal) and like me thought it was a radar then it will enlighten you (Dohh). It explains why the RN was so keen on 2 man crews.

A lot of it is very technical and I skimmed over several paragraphs as they might as well have been in chinese to me but I found it interesting and it does explain some of the very controversial reasoning behind the Fulmar and Firefly designs.

Just above funnel on HMS Illustrious in 1940.

 

[Glider]

thanks for this

 

[Shortround6]

Thank you.

I read that the second seater on the Fulmar was to operate radio navigation equipment (but was not a navigator) but without any explanation on how it worked (either technically, also above my head or operationally)

 

[yulzari]

Exactly the reason the FAA wanted 2 seaters. The rear chappie was a TAG (Telegraphist Air Gunner) seaman not a navigator officer and his job was to operate this kit to allow the carrier to be found even in bad North Atlantic weather. In the Skua they gave him a gun as he was there anyway but did not bother in the Fulmar and Firefly. At 300 mph+ a hand held gun was never going to make a difference and a turret was too heavy (vis the Roc.)

It is worth noting the Swordfish, that had to have more exact navigation to a strike target, carried both a TAG and a navigator. When they were laying mines on the Dutch and German coast they carried an extra tank in the rear cockpit and it is telling that they dropped the TAG not the navigator knowing that the rear gun was useless and their land airfield fixed.

 

[FAA Pilot]

Royal Navy's Fleet Air Arm have "Observers" NOT Navigators. Towards the end of my service (late '80s) there were moves to rename the Observer but to the best of my knowledge tradition (for good or bad) has held and the FAA still use the term Observer.
The Observer historically was a navigator and now might be better termed a Tactical Officer or some other term, as he/she have access to the various aircraft sensors and therefore "fight" the aircraft.
Not sure about '30s, WW2 and shortly after, but the Observer is a Officer, as have been all FAA Pilots since the end of non-Commissioned Pilots.
The TAG (Telegraphist Air Gunner) was a Sailor that is non-Commissioned, in naval parlance a Rating or Senior Rating. During my FAA service (1978-1990) in the ASW world without the Aircrewman (no flying females then) we could not find a Submarine without the Aircrewman because they were the Sonar (Active or Passive) Operator.
From what I have read, I understand that at least on Skua Squadrons, the back-seaters were a mix of Observers (officers) and TAG's (ratings). How much formal navigational training the TAGs received I do not know. Don't know about back-seaters on Fulmar Squadrons, but I am guessing that as WW2 progressed the proportion of Observers increased and Firefly back-seaters were probably mostly (all?) Observers.
The Barracuda, being a 3 seater was, I think, a Pilot, Observer, TAG crew, also the Avenger when it came into service, though the USN had the pilot navigating their Avengers.
Why their "Lordships" at the Admiralty believed that a Naval aircraft need someone other than the Pilot to navigate I don't know. The USN and Japanese navy managed perfectly well.
Lastly the link at the beginning of this thread no longer works. Any ideas as to where the article now resides?

 

[cherry blossom]

The article is now at https://www.nonstopsystems.com/radio/pdf-hell/article-part3a-1947-Quinn.pdf

 

[Admiral Beez]

Exactly the reason the FAA wanted 2 seaters. The rear chappie was a TAG (Telegraphist Air Gunner) seaman not a navigator officer and his job was to operate this kit to allow the carrier to be found even in bad North Atlantic weather.

I'd read that the TAG's primary job was to find the carrier when the aircraft was outside the range of the radio beacon, i.e. beyond the horizon. Presumably the pilots of Sea Hurricanes, Martlets and Seafires (and their USN cousins flying F3Fs, F4Fs, etc.) were equipped and trained to use the RDF kit.

 

[Admiral Beez]

Interesting article here, asserting that the rear gunner in the Skua wasn't a navigator at all, http://dinger.byethost5.com/blackburn_skua.htm?i=1

Floyd Richards, a TAG with 803 Squadron, described to me how beacon navigation worked: "The beacon made one revolution per minute – initially we were issued with chronometers to time the signal, but they ran out with aircraft getting shot down, and they were very expensive," he explained. "We subsequently used wristwatches."You would receive your bearing onto the ship, say 90°, but we would receive and steer the reciprocal of that – 180° of that bearing, and we would use that as a bearing. It would be all right if the ship was stationary but of course it was moving. You would always approach from the stern. Without a chronometer to time it precisely, if the signal came out earlier, for example ten seconds less than a minute, and the next came up at nine or 12 you would turn to the right or left depending on where you were in relation to the ship." With a chronometer, the time difference could be worked out precisely and equated to a course, but with a wristwatch it was a case of 'less than a minute, steer one way, more than a minute, steer the other way'. Eventually, the 'beeps' would be at precise one-minute intervals and this meant you were heading straight for the carrier."

It's the last sentence below that suggests the two seat position is needed. Here's an article on the R1110 beacon receiver, Some good info here Naval air-telegraphy at the start of WW2

the TAG was essential to the pilot finding his way back to the carrier; the Skua carried an ingenious device, the R1110 receiver that picked up radio signals from a Type 72 rotating beacon on the aircraft carrier The process was complicated, and could never have been done by the pilot, hence the need for a second crewman.

​

 

[FAA Pilot]

The article is now at https://www.nonstopsystems.com/radio/pdf-hell/article-part3a-1947-Quinn.pdf

Thank you for the updated link.
Iain

 

[Koopernic]

This is an interesting area.

I read an account of a Hohtenweil radar equipped Junkers Ju 290 mission over the Bay of Biscay (must have been late 43 or early 1944). It was actually an article about the chronometers on board the Ju 290 for accurate navigation.

There the radar operator of the Ju 290 describes spotting RN carriers and seeing the movement of the aircraft leaving the deck.

He notes that the knew they were safe because the fighters couldn't fly more than 80km from the aircraft carriers and all they had to do was keep that distance.

Presumably the fighters, I think martlets?, were limited in some way to that range, or so the Germans had been told. Larger aircraft with an navigator observer might have better equipment able to home greater distances and actually navigate by plotting and celestial rather than just homing.

These carriers gave the Allied shipping complete protection against a potential attack by the limited German multi engine aircraft.

*****

Another interesting area is the use of radio homing rescue becons. The historian Fritz Trenkle mentions the Luftwaffe had something.

 

[RCAFson]

This is an interesting area.

I read an account of a Hohtenweil radar equipped Junkers Ju 290 mission over the Bay of Biscay (must have been late 43 or early 1944). It was actually an article about the chronometers on board the Ju 290 for accurate navigation.

There the radar operator of the Ju 290 describes spotting RN carriers and seeing the movement of the aircraft leaving the deck.

He notes that the knew they were safe because the fighters couldn't fly more than 80km from the aircraft carriers and all they had to do was keep that distance.

Presumably the fighters, I think martlets?, were limited in some way to that range, or so the Germans had been told. Larger aircraft with an navigator observer might have better equipment able to home greater distances and actually navigate by plotting and celestial rather than just homing.

These carriers gave the Allied shipping complete protection against a potential attack by the limited German multi engine aircraft.

*****

Another interesting area is the use of radio homing rescue becons. The historian Fritz Trenkle mentions the Luftwaffe had something.

80km was well inside Type 279 or 281 radar range. If the RN carrier's radar could see the Ju290 then it could also see their own fighters (and their IFF) and use GCI to direct the fighters to attack and destroy the Ju290, and then vector the fighter back to the carrier. The Type 72 homing beacon was designed, pre-radar as a method of homing aircraft back to the carrier, but once reliable long range AW radar became available, the Type 72 (and the USN ZB beacon which was also used by the RN) became less important.

 

[Koopernic]

80km was well inside Type 279 or 281 radar range. If the RN carrier's radar could see the Ju290 then it could also see their own fighters (and their IFF) and use GCI to direct the fighters to attack and destroy the Ju290, and then vector the fighter back to the carrier. The Type 72 homing beacon was designed, pre-radar as a method of homing aircraft back to the carrier, but once reliable long range AW radar became available, the Type 72 (and the USN ZB beacon which was also used by the RN) became less important.

The use of 279 radar (a 7.5m radar of modest bearing accuracy, even when combined with IFF transponder for range extension (rather than relying on a miniscule reflection) still requires a voice link. I would think it would be reasonably reliable but not totally dependable and requires a lot of radio traffic and human intervention when large numbers of aircraft are involved. Yes workable but it will have its operational problems.

On a technical point: the beacons being written about above are not homing beacons. They broadcast the compass heading the beam is pointing to at the time the aircraft is within the beam so the pilot merely has to fly a reciprocal heading to get to the carrier. They don't require a direction finding loop aerial. There were a number of similar systems in use. In fact the Germans operated a over the horizon version called sonnenstrahl (sun beam) which 'talked' verbally the current heading relative to the beam into any ordinary radio. It was so useful the allies used it and when the Germans encoded it the allies bombed the station until the Germans unencoded it again. Another system used by night fighters "Bernhard/Bernhardine" printed the relative heading on ticker tape.

I digress.

As far as intercepting the Ju 290, the crew felt safe with the radar operators stating "we knew they couldn't venture too far from the aircraft carrier".

Since the Ju 290 had a radar capable of detecting any interceptors launched from an aircraft carrier it would merely be a matter of diving to 500m to get below the radar horizin or turning tail

In retrospect I would say what would happen is this. If interceptors were despatched the Ju 290 radar would detect them on its own radar. With the Interceptors moving at 600kmh/372mph and the bomber at 400kmh/248mph (worst case) the Ju 290 would be out of range of the type 279. Alternatively a dive.

 

[RCAFson]

The use of 279 radar (a 7.5m radar of modest bearing accuracy, even when combined with IFF transponder for range extension (rather than relying on a miniscule reflection) still requires a voice link. I would think it would be reasonably reliable but not totally dependable and requires a lot of radio traffic and human intervention when large numbers of aircraft are involved. Yes workable but it will have its operational problems.

On a technical point: the beacons being written about above are not homing beacons. They broadcast the compass heading the beam is pointing to at the time the aircraft is within the beam so the pilot merely has to fly a reciprocal heading to get to the carrier. They don't require a direction finding loop aerial. There were a number of similar systems in use. In fact the Germans operated a over the horizon version called sonnenstrahl (sun beam) which 'talked' verbally the current heading relative to the beam into any ordinary radio. It was so useful the allies used it and when the Germans encoded it the allies bombed the station until the Germans unencoded it again. Another system used by night fighters "Bernhard/Bernhardine" printed the relative heading on ticker tape.

I digress.

As far as intercepting the Ju 290, the crew felt safe with the radar operators stating "we knew they couldn't venture too far from the aircraft carrier".

Since the Ju 290 had a radar capable of detecting any interceptors launched from an aircraft carrier it would merely be a matter of diving to 500m to get below the radar horizin or turning tail

In retrospect I would say what would happen is this. If interceptors were despatched the Ju 290 radar would detect them on its own radar. With the Interceptors moving at 600kmh/372mph and the bomber at 400kmh/248mph (worst case) the Ju 290 would be out of range of the type 279. Alternatively a dive.

Sea Hurricane IICs from HMS Nairana, claimed 3 x Ju290s on 25 and on 26 May 1944:

'I pressed home my own attack, hitting the Junkers repeatedly at close
range. It crashed into the sea and exploded. All that remained of the
Junkers was an oil slick and a few floating pieces of debris. It all happened
unbelievably quickly."

Later that afternoon Sub Lts Sam Mearns, at the controls of NF69I8/7D,
and Frank Wallis attacked two more Ju 290s, bringing down 'IV+GK
(Wk-Nr 164) of 1./FAG 5 flown by Leutnant Kurt Nonneberg. The huge
aircraft broke up on impact, although four of his crew were picked up. It
is perhaps appropriate to give the last word to a survivor of the final
Hurricane victory. He said;

'We left Mont de Marsan at 1100 hrs, led by Hauptmann Pavletke.
Both aircraft were fitted with Hohentweil radar, and flew close for
mutual protection at about 1000 ft to continue the convoy surveillance.
However, after about six-and-a-half hours we were unexpectedly attacked
by Hurricanes before we sighted the convoy.

'The tail gunner and rear dorsal gunner opened fire but the latter's gun
jammed. In an attack from fine astern, the port inner engine was set on
fire and the port wing damaged. The second pilot, who was at the
controls, was seriously wounded, whereupon the first pilot took over and
ditched the aircraft, in the course of which manoeuvre the tail and port
wing struck the water and broke off." (Hurricane Aces)