What are the Nav or Comms aerials in this picture?

[Postfade]

Working through my 1960s photos at Changi I began to notice the pair of aerials in the background of many of the wide shots. Over the years it has dawned on me that every RAF and RN airfield has these located nearby.
I'm referring to the ones in the distance, top left of this photo.
Would they be comms aerials and why always a pair?
The planes on the pan, apart from the usual 48 sqn Hastings, are 8 Indian Air Force Vampire T55's on a ferry flight from Indonesia, a Royal Ceylon Air Force Heron and an Aussie Canberra and C-130. A typical day I guess in March 1963!
http://www.davidtaylorsound.co.uk/share/Aircraft%20pics/Changi%20-8%20IAF%20Vampires-Ceylonese%20Heron-Aussie%20Canberra%20and%20C130-March%201963-New113A.jpg

David Taylor.

[chiglet]

Probably the Tx/Rx ariel towers.

[GOLF_BRAVO_ZULU]

chiglet has my vote.

Interesting to see a Hercules, Heron and Hastings sharing the same pan. These days, in Hercules, Herons and Hastings, harmony hardly ever happens!

[wz662]

Just goes to show how antiquated the Herc is, and they still have the cheek to be selling new ones. :rolleyes:

[sycamore]

Don`t knock the Herc, it`s the t/prop equivalent of the Dak/C-47,and it will probably outlast it`s Douglas cousin in 30-40 yrs time,but I wouldn`t give you good odds; it can go anywhere,do anything,as long as you can get it started,one way or another,and there are many ways,(can`t speak about`j` models),but for an `elderly aeroplane`,it can sure do the ` biz`... got 17000
engine hrs in Herks and only 1 shutdown, a bit of a `non-event` anyway....Syc

[lauriebe]

The Canberra looks to be A84-240. If so, this aircraft took part in the RAAF's first jet bombing mission against CT targets in the jungles of Malaya on 3 Sep 58. I believe it is currently on display at the RNZAF Museum.

[Kieron Kirk]

Hello lauriebe,

Happy New Year.

A84-240 is indeed at the museum outside Christchurch.

Ciarain.

[lauriebe]

Hi Ciarain, a happy new year to you too.

Thanks for confirming the location.

Laurie.

[Tim McLelland]

Beautiful photo! Any more?!

[Postfade]

Here's another wide view of the Western dispersal at Changi in 1962. Those two aerials are visible in the distance again. I've seen them at other RAF airfields and there are a pair visible near Yeovilton that can been seen from the A303. Also I think another one, down the road near Boscombe Down.

http://www.davidtaylorsound.co.uk/share/Aircraft%20pics/Changi-Comet%204C%20XR395%20with%20FEAC%20and%2052%20Sqn%20Valettas-S665A.jpg

The Comet 4C in this pic is XR395 and the Valettas are from 52 Sqn Butterworth (although wearing no markings) and FEAC far side of the pan.
48 sqn Hastings as usual.

David Taylor.

[GlueBall]

Thanks for contributing these historical photos.

[Hot 'n' High]

Chiglet is 50% correct from my memory of my time as a baby Comms techie. The remote aerials are on the Tx site which was always off-station while the Rx site is on-station, usually on/about ATC. The idea (if my faded memory serves me right) is that, often with several frequencies in use at any time, a Tx on one frequency could break through on the Rx of another (all to do with frequency harmonics and all that!) if the Tx and Rx aerials were co-located. Thus the Tx aerials were placed well away from the Rx aerials – by several miles. One reason for the Rx aerials being on site was to do with DF - no point in providing a Homing service to a field a couple of miles away from the runway! It also reduced Radhaz on base with the Tx aerials being off-site. Anyway, please blame Postfade for unleashing the Geek in me. I do apologise and will crawl back into my cave! If it helps, even I think I'm sad!!!! :8

[Blacksheep]

A very evocative picture and I've taken the liberty of forwarding them to an old colleague in Brunei who served on 48 Squadron with Hastings at about that time. They'll bring tears to his old sweat's eyes, they will. ;)

In my time the western dispersal was occupied by 52 Squadron with Andover C1s, FEAF Comms Flight with Andover CC2s and VASF who would have the daily VC10 service, and visiting Britannias, C130s and just about anything else, up to and including USAF B52s lined up on the far side. (Those aerials were there then as well.)

[Postfade]

A couple more for your friend (I lots of Hastings pics!)

http://www.davidtaylorsound.co.uk/share/Aircraft%20pics/48%20Sqn%20line-up%20changi%201961-S1009A.jpg

The 48 sqn line-up at Changi in late 1961. There's one of the FEAC VIP Hastings in there as well, second away from camera.

http://www.davidtaylorsound.co.uk/share/Aircraft%20pics/Squeezing%20a%20LandRover%20into%20a%20Hastings-TG569-48%20sq-1963-.jpg

Pity the poor despatchers, here squeezing an Army LandRover into TG569.
Better with a Beverley of course, but they were at Seletar. Then along came the Argosy's at Changi, which must have made this a whole lot easier!

David Taylor.

[2 sheds]

Hot 'n' High

Thus the Tx aerials were placed well away from the Rx aerials – by several miles. One reason for the Rx aerials being on site was to do with DF

Are you saying that the DF was dependent on the position of the RX aerials? Not a discrete DF aerial?

2 s

[Mickj3]

They are either the Rx or Tx towers on which would be mounted the ground to air VHF/UHF aerials. The majority of the towers were 90ft high but I came across a small number of 120ft ones and a lesser number of 60ft ones. The stations standby V & U aerials were generaly mounted on the ATCs Coronet.:)

[Postfade]

Thanks guys.

So these are the RX aerials on the tower at Changi then?

http://www.davidtaylorsound.co.uk/share/Aircraft%20pics/Changi%20Control%20Tower-1961-SLargeS310B.jpg

David Taylor.

[Warmtoast]

Are you saying that the DF was dependent on the position of the RX aerials? Not a discrete DF aerial?


Main reason for siting the RX and TX aerials some distance apart was to avoid the RX circuits being overloaded by a TX blasting away on the same frequency just a few feet away.

At Biggin Hill in the 1950's the RX aerials were on the airfield with the TX aerials located at Titsey on the North Downs ridge a couple of miles to the SW of the airfield. The TX aerial mast was still in the Titsey area when I last passed through the area, but whether it's still used for civilian airfield use I don't know. A bit further along the ridge in the Woldingham/Warlingham area was an aerial complex which in the mid-1950's catered for RAF (Metropolitan Sector Operations Centre) communications and was co-located with Ministry of Civil Aviation TX facilities.

The DF station at Biggin in 1955 was a relatively new CR/DF (Cathode Ray Direction Finder) installation which was installed in a small white hut alongside the main runway as shown below. Almost next to it was the Biggin GCA (Ground Controlled Approach - a Gilffilin MPN4-A). This was a self-contained unit that had its own independent transmitters and receivers with aerials on the roof of the truck/trailer.

http://i145.photobucket.com/albums/r231/thawes/BigginDFGCAaerials1955.jpg

http://i145.photobucket.com/albums/r231/thawes/CR-DF.jpg

Cathode Ray DF installation. A remote repeater head was situated in the control tower. The bearing of the aircraft transmission was done automatically with the bearing seen as a trace on the screen. The circumference of the screen was marked 0 to 359, the trace pointing to the bearing of the aircraft.

[Postfade]

Warmtoast:

Thanks for that info. I can now identify the DF building in this pic of a Shackleton taxying in.

http://www.davidtaylorsound.co.uk/share/Aircraft%20pics/Shackleton%201A%20E%20taxies-1961-S621A.jpg

Is it GCA radar on the right of the picture below then, a fixed installation?

http://www.davidtaylorsound.co.uk/share/Aircraft%20pics/Canberra%20burst%20tyre-Changi%201963-S1012A.jpg

Oh ...the Canberra crew do look a little 'lost' in that photo don't they. They'd had a tyre burst and were awaiting recovery.

David T

[Warmtoast]

Is it GCA radar on the right of the picture below then, a fixed installation?


It is not a GCA radar. GCA installations have two radar aerials, a rotating azimuth aerial and a ‘nodding’ elevation aerial for glidepath information. The aerial shown is I think an airfield radar (made by Decca?) which were installed fairly widely on RAF airfields from the mid 1950’s onwards and was a rotating all-round surveillance radar for aircraft in the local area.
'Crude' talkdowns could be made with these radars but Prescision Approach radars such as the Decca type 424 came a little later.

[Postfade]

Warmtoast- so if that's not a GCA radar set, I wonder how non-visual approaches were made at RAF Changi in the 60's? I don't recall a dual system as you explain the GCA to be. There were certainly regular night landings, with the local Hastings and Shacks flying at night and often the Transport Command Comets and Brits came over night, so I expect some talkdown facility would have existed. There were certainly many days of wet weather with low cloud in the monsoon months.
David T.

[Warmtoast]

Postfade

I wonder how non-visual approaches were made at RAF Changi in the 60's? I don't recall a dual system as you explain the GCA to be.

I don't recall what was installed at Changi, but I would consider it most unlikely to be a GCA, which by the early 1960's were being phased out of RAF service to be replaced by PAR's (Precision Approach Radars) at fighter bases. A better bet at Changi would be an ILS (Instrument Landing System). ILS's were installed at RAF Transport Command stations from the late 1950's onwards. The photo below, taken whilst I was at RAF Abingdon in the summer of 1959, shows the newly installed ILS and the fitting party from RAF Henlow, who were supported by a civilian technician from the manufacturers (Standard Telephones and Cables).

http://i145.photobucket.com/albums/r231/thawes/AbingdonILS1959.jpg

For further information have a look at wikipedia's entries for GCA and ILS here:

Ground-controlled approach - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Ground-controlled_approach)

Instrument landing system - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Instrument_landing_system)

[Postfade]

Really, ILS at an overseas RAF station in the early 60s? I certainly don't recall a ILS array and even RAF Northolt here in the UK, was still doing GCA approaches until a few years ago. Loved to hear that 'warm female voice' saying "Your slightly above the glide slope, correcting nicely, 2 miles from touchdown" etc.
DT

[iceni]

I more than likely worked on three of the five aircraft in this photo. The two Valettas and the Comet.

Excellent photos.

[Hyperborean]

Couple of minor nit picks Warmtoast. Rotating azimuth aerials not necessary on GCA/PAR some had aerials which swept only an arc through the final approach track. I am not old enough to remember the first GCAs but I vaguely recall information regarding the "search element" of GCA, which would of course require 360 degree coverage. Also Decca 424 was not a PAR as it only provided azimuth information so was used for SRAs down to half a mile. Incidentally I understand that the 424 was developed from a marine radar. In its turn it was developed into the 430.

[Hot 'n' High]

Hi 2 sheds, (Post #15) what I meant was that the reason that all Tx aerials and all Rx aerials were separated geographically was to prevent breakthrough from Tx to Rx as confirmed by Warmtoast - even, in some cases, where a Tx is made on one frequency but breaks through on another (the harmonics issue). However, what I was trying to explain was that one of the reasons for the logic in having the Tx group of aerials off-site and Rx group of aerials on-site was, in part, to ensure the DF aerial was somewhere on the airfield (as opposed to in a field amongst some sheep a few miles away). The DF did use a separate array, but, as an Rx system, it needed to be away from the transmitters – hence Tx off-site, Rx on-site! Hope that clarifies my Post #14.

Now, of course, when it came to a Grey Funnel Line landing pad….! Well, you did what you could to minimise the issues but, for several reasons, having a Tx site trailing a couple of miles behind “Mother” was a bit of a non-starter. If nothing else, there was a risk of over-exuberant pilots using it as a “splash target” on their way home or even mistaking it for “Mother” in the heat of the moment! ;) There were other, more practical reasons, but I can just picture the "splash target" - or worse - scenario!!!!!!

[2 sheds]

Hot 'n' High

Thanks for that - probably me being dim.

2 s

[AvroLincoln]

Many thanks for the reminder of the Decca 424, known in the RAF as the ACR 7D, on which I performed 3rd line servicing throughout most of the 1960s, while I was based at RAF North Luffenham.
For geeks like myself, here is a very thorough article describing this equipment and its use:
decco type | decca type | airfield radar | 1953 | 1232 | Flight Archive (http://www.flightglobal.com/pdfarchive/view/1953/1953%20-%201232.html)

[Hot 'n' High]

2 Sheds

No probs. My vague initial explanation me thinks! :O

H 'n' H