10Q/2 L/R indicator and Beam Approach (1 Viewer)

[yahya]

I'm looking for a definite clarification of the purpose and utilization of the characteristic 10Q/2 L/R indicator on WW II British planes.

Apparently, it was a part of the Beam Approach (BABS) system, but there were instances when it was connected to the HF receiver, too.

A photo of a '10Q/2' can be found here:


View: https://www.flickr.com/photos/edk7/31290492926/

Apparently, the indicator was connected to the R1155 HF receiver on large airplanes, like the Lancaster. However, it could be spotted on smaller planes, as well, like the Mosquito. The purpose in the latter setup remains unknown.

The website below elaborates the interconnection between the HF receiver and that very indicator:

Toebehoren van de T1154

The setup with the R1155, however, suggests that the 10Q/2 acted as a simple direction finder in conjunction with the loop antenna operating on MF/HF.

Another use of the indicator was probably with the ARI TR3567 blind-landing system, which employed the Eureka beacon. That could be more plausible on smaller aircraft like the Mosquito or PR Spitfires.

Perhaps this film from the IWM, which is not available online, could clarify the matter:

EUREKA BA [Main Title]

A technical instructional film with extensive use of animated diagrams, illustrating the basic principles and uses of the BABS Mark II "Eureka" radar system that uses a ground based transponder and an airborne transceiver for aircraft navigation purposes.

www.iwm.org.uk

Another specialized website mentioned the specs of various BABS systems, albeit without any sketches:

EW - Eureka/Rebecca

That said, what was the ultimate purpose and use of the 10Q/2?

The images below show the indicator connected to the R1155 HF receiver.

 

[Crimea_River]

A bit long winded but this video explains use as a direction finder:


View: https://www.youtube.com/watch?v=0EIOvUI8VEE

 

[yahya]

Thank you for sharing this interesting video.

Do you happen to know if the R1155 receiver was also used on the F-8 PR Mosquito used by the USAAF, since the version sported the 10Q/2 indicator on the navigator's side of the instrument panel?

 

[Crimea_River]

No the F-8 was fitted out with an RA-10DB as far as I know. Here's a description of the radio compass setup.

The above says the indicator is an IN-4A.

 

[yahya]

Thank you for the reply.

This document https://www.aahs-online.org/pubs/journals/files/521036.pdf clearly shows on p. 43 that the F-8 was fitted with the British 10Q/2 two-needle L/R indicator on the navigator's instrument panel unless the a/c were later retrofitted with the Bendix MN-26 radio compass as you suggested. I am not sure if the 10Q/2 could be then a part of the BABS blind landing systems, something of a must given typical English weather.

The RA-10DB set was relatively large as evidenced by its manual available from here: https://aafradio.org/docs/RA-10DB.pdf . There are no signs of a loop antenna on the F-8 as I can see. However, a MF/HF long wire antenna stretched between the antenna mast and the vertical stabilizer can be seen here:

https://ia601304.us.archive.org/0/items/NIX-EL-2003-00302/EL-2003-00302.jpg

Perhaps it was a part of the British TR9D HF comm radio or a more sophisticated US-made HF radio.

I agree that an ADF would be beneficial on the long-range recce flights in adverse weather as the crew could tune in commercial MF stations and use them as NDBs. I think that this was practiced well into the 1950s and 1960s eg. on the Lockheed U-2s.

 

[Crimea_River]

Your knowledge of these systems appears to be greater than mine so I can't challenge what you are saying. My reference is this:

The picture of the panel containing the indicator therein is unhelpful, as they managed to get the camera positioned perfectly so that the glare obscured the face of the instrument.

I'm aware of the size of the RA-10DB but it's really not that big. Our organization, which is restoring Mosquito RS700 to its condition when flying postwar with Spartan Air Services, has one of these units to install in our machine. It measures 16.625 x 10.3125 x 7.375 inches which is actually a bit smaller than a R1155.

 

[yahya]

You're right that the F-8 Mosquito was fitted with the rich US-made avionics as evidenced by the document that you quoted. So, I can be assumed that no British-made avionics was used on the F-8, particularly the 10Q/2 indicator.

Bendix IN-4A radio compass indicator seen on top right.