Mariner searchlight

[WATU]

I have been reading Carey's "Sighted Sub, Sank Same" book about the USN's air campaign against the U-boats. P86-88 has an account that surprised me. A PBM-3C Mariner of VP-74 was involved in a night attack on a U-boat in the South Atlantic off the South American coast on 4 July 1943. The aircraft crashed and was lost but the U-boat crew who were subsequently captured denied that they shot the plane down. A theory is that the aircraft searchlight slung under the starboard wing might have been a problem. Firstly the searchlight adversely affected the aircraft aerodynamics. Secondly when in use at night it reduced the pilot's ability to see the instruments. ".....a previously dark cockpit suddenly being flooded with light". At low level the inability to see the radio altimeter could have been crucial alongside losing vision of the sea surface only 50 feet below. The plane could therefore have hit the surface.
I am familiar with the Coastal Command Leigh Light and that seems to have been fitted to minimise any vision impact on the crew beyond wiping out night vision by the illumination of the target directly in front.
I am not familiar with this US million candle searchlight, nor do I know that much about the Mariner. Blinding the cockpit seems a huge downside that should have been identified early on in trials. Was this a trial installation? Were many fitted in that position? Were other problems experienced with it? Was the design changed?
Anyone able to shed light (pun intended) on the equipment?

 

[EwenS]

I have a note that the PBM-3C Mariners of VP-201 began using the "L-8C searchlight" during the autumn of 1943 with its use then spreading to other units. At July 1943 this may have been an experimental version. But I've never seen a photo of a Mariner with one.

There was a podded version of the British Leigh Light able to be carried under the wing of Liberator and Catalina aircraft which was introduced sometime between May and Oct 1943. I've never heard of any pilots having troubles with it despite it being widely fitted to the Coastal Command fleets of these aircraft.

Edit:- Another possibility for the loss is what is now called "target fixation". Pilots concentrate so hard on the target that they blank out everything else until they realise too late that they have a problem. Next thing they know they have crashed.

 

[WATU]

I have a note that the PBM-3C Mariners of VP-201 began using the "L-8C searchlight" during the autumn of 1943 with its use then spreading to other units. At July 1943 this may have been an experimental version. But I've never seen a photo of a Mariner with one.

There was a podded version of the British Leigh Light able to be carried under the wing of Liberator and Catalina aircraft which was introduced sometime between May and Oct 1943. I've never heard of any pilots having troubles with it despite it being widely fitted to the Coastal Command fleets of these aircraft.

View attachment 731006

Edit:- Another possibility for the loss is what is now called "target fixation". Pilots concentrate so hard on the target that they blank out everything else until they realise too late that they have a problem. Next thing they know they have crashed.

Thanks. Yes, at 50 feet there is no room for error. Nobody knows what happened so it is all speculation. I just find it surprising that a searchlight was used on ops with such a glaring (another pun) fault.

 

[cvairwerks]

Wish my uncle was still alive, as he was an aircraft commander in VP-74 at the time. For that time period, all the references I've come across and all the photos I've located, VP-74 had PBM-1's and PBM-3S's, with a few scattered references to PBM-3's.

The couple of photos I found with the searchlight were PBM-5's and the light was installed on the right wing hard point, outboard of the nacelle. The light probably had minimal effect on the left seater, but might have casued a problem with the right seater, depending on the az/el of the reflector at any instant.

 

[WATU]

Wish my uncle was still alive, as he was an aircraft commander in VP-74 at the time. For that time period, all the references I've come across and all the photos I've located, VP-74 had PBM-1's and PBM-3S's, with a few scattered references to PBM-3's.

The couple of photos I found with the searchlight were PBM-5's and the light was installed on the right wing hard point, outboard of the nacelle. The light probably had minimal effect on the left seater, but might have casued a problem with the right seater, depending on the az/el of the reflector at any instant.

Wow, he would have been the man. The quote about the cockpit being flooded with light is from a letter by William J Barnard of VP-74. It sounds like he is a pilot but that is not specifically stated. He definitely talks about the pilot (as opposed to the co-pilot), presumably in the left seat of the Mariner, losing sight of his instruments. That is despite the searchlight being on the right wing as you describe. The main pilot would always want to have control during an attack with only rare exceptions.

 

[ThomasP]

If it is of any help, the L-8 aircraft searchlight was the main guts of the Leigh Light modified for manufacture by General Electric (US). The earlier 'pod' type package was replaced with a faired housing under the wing. Unless you look closely it is often not noticeable under the Mariner wing.

The L-8 had a 3.25° wide 65,000,000 CP beam, with train in azimuth of +/-15° and vertical of 45° (+10°/-35°?) total.

(from Handbook of Instructions, Aircraft Searchlight Type L-8)

 

[WATU]

If it is of any help, the L-8 aircraft searchlight was the main guts of the Leigh Light modified for manufacture by General Electric (US). The earlier 'pod' type package was replaced with a faired housing under the wing. Unless you look closely it is often not noticeable under the Mariner wing.

The L-8 had a 3.25° wide 65,000,000 CP beam, with train in azimuth of +/-15° and vertical of 45° (+10°/-35°?) total.

(from Handbook of Instructions, Aircraft Searchlight Type L-8)
View attachment 731055
View attachment 731056

Very interesting, thanks. Hard to tell if there is a direct line of sight from the glass front of the light to the cockpit. If it did dazzle the pilots there seems to be two solutions to me. One is to move the fairing backwards but that would have stability/aerodynamic issues, albeit relatively minor. The simpler answer would be to add an element of shielding to the left side of the searchlight glass. That should be possible without impacting on the forward beam.

 

[ThomasP]

They would have done that if there was a problem. The regular Leigh Light installations had no particular problem with blinding the pilot(s).

 

[WATU]

They would have done that if there was a problem. The regular Leigh Light installations had no particular problem with blinding the pilot(s).

Agreed. Never read anything that mentions Leigh Light affecting the ability to see instruments. It did mess up night vision outside of the aircraft that was inevitable with all such devices.