DME Gauges history?
Joined: May 1999
Aviation Qualifications: ATP+Mil
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From: Quite near 'An aerodrome somewhere in England'
The Vampire 11 had a Rebecca 8 set, as did the Jet Provost and Hunter. In 'range only' mode, if you were lucky it had a range of about 40 nm; in 'homing' mode about 20....
The control box was a large, clunky thing with large bakelite rotary knobs. One control selected the letter and the other the number of the associated Eureka 7 channel; for example, Cranwell was C4 and Cottesmore D5 (I think). The morse coding rate for the Eur7 was very student friendly - about 1 word per week! You had to check it as it was quite common for the Rebecca to lock onto a different station to the one you'd selected.
Somehow we flew radio navigation exercises using nothing more than Eur7 and UDF, then flew a DME let down at base using this contraption. At least we had the left/right indicator, rather than the CRT screen the guys who flew Pigs had! You went outbound in the 'DME safety lane', then faffed with L/R and the DI to establish the correct inbound approach course....
Fortunately we'd all had several sessions in the Link trainer before trying it for real.
The 'swingometer' range needle used to hunt around the dial unless the Rebecca could sniff out a station; once I was just pulling off the target at Pembrey when the needle went clockwise at precisely the same rate as the g-meter's needle normally moved - except that it kept going...
For a moment I eased off the g as a reflex in case I was overstressing....fortunately I was already climbing. We used to pull out of the dive and immediately check the mirror for the 25 lb bomb smoke - having the distraction of the Rebecca needle moving round the dial out of the corner of your eye was most unwelcome!
The bandwidth of Eureka/Rebecca was colossal - about 4-5 MHz if I recall correctly. When the JP5A came in with VOR/DME, it seemed like the space age. This was about 1974! But the wonderful Gnat with its offset TACAN was truly magical! We had non-offset TACAN in the GT6 Hunters at Valley, but all bar 2 of the jets at Brawdy had the old Rebecca. The Mk9s had ADF, but no-one taught us how to use it - we just used to listen to music on it. A chum, Dick 'Whizzbang' was a bit of a culture vulture and had a memorable time rocketing with SNEBs at Pembrey whilst listening to 'Ride of the Valkyries' on BBC Radio 3!
The guys at 45/58 Sqns, RAF Wittering, had some NDB-to-DME approach system. If you were brave enough, you did the initial homing and inbound turn on NDB with the Rebecca turned off (as it interfered with the ADF), then turned the Rebecca on to fly the final approach. I wouldn't fancy doing that in a Cherokee, let alone a Hunter 9!
However, the DME let down was probably a lot easier than the CR DF 'Jet Instrument Approach Chart' I have dated 1954. The CR DF high level descent for RAF Merryfield had an initial overhead approach not below 12000 ft and went out on 115 degM to about 25 miles to 'half initial approach altitude plus 2000', then inbound on 285 degM with a check altitude of 3500 ft - and a min app. alt. of 1350 ft. Bearing in mind the field elevation was 145 ft, this looks like rather a useless procedure. Presumably you made the relevant calls to 'Merryfield Homer' on 104.94 Mc/s (this was long before the days of MHz) and switched to 'Merryfield Tower' on 102.42 Mc/s if you were fortunate enough to become visual!
The control box was a large, clunky thing with large bakelite rotary knobs. One control selected the letter and the other the number of the associated Eureka 7 channel; for example, Cranwell was C4 and Cottesmore D5 (I think). The morse coding rate for the Eur7 was very student friendly - about 1 word per week! You had to check it as it was quite common for the Rebecca to lock onto a different station to the one you'd selected.
Somehow we flew radio navigation exercises using nothing more than Eur7 and UDF, then flew a DME let down at base using this contraption. At least we had the left/right indicator, rather than the CRT screen the guys who flew Pigs had! You went outbound in the 'DME safety lane', then faffed with L/R and the DI to establish the correct inbound approach course....
Fortunately we'd all had several sessions in the Link trainer before trying it for real.The 'swingometer' range needle used to hunt around the dial unless the Rebecca could sniff out a station; once I was just pulling off the target at Pembrey when the needle went clockwise at precisely the same rate as the g-meter's needle normally moved - except that it kept going...
For a moment I eased off the g as a reflex in case I was overstressing....fortunately I was already climbing. We used to pull out of the dive and immediately check the mirror for the 25 lb bomb smoke - having the distraction of the Rebecca needle moving round the dial out of the corner of your eye was most unwelcome!The bandwidth of Eureka/Rebecca was colossal - about 4-5 MHz if I recall correctly. When the JP5A came in with VOR/DME, it seemed like the space age. This was about 1974! But the wonderful Gnat with its offset TACAN was truly magical! We had non-offset TACAN in the GT6 Hunters at Valley, but all bar 2 of the jets at Brawdy had the old Rebecca. The Mk9s had ADF, but no-one taught us how to use it - we just used to listen to music on it. A chum, Dick 'Whizzbang' was a bit of a culture vulture and had a memorable time rocketing with SNEBs at Pembrey whilst listening to 'Ride of the Valkyries' on BBC Radio 3!
The guys at 45/58 Sqns, RAF Wittering, had some NDB-to-DME approach system. If you were brave enough, you did the initial homing and inbound turn on NDB with the Rebecca turned off (as it interfered with the ADF), then turned the Rebecca on to fly the final approach. I wouldn't fancy doing that in a Cherokee, let alone a Hunter 9!
However, the DME let down was probably a lot easier than the CR DF 'Jet Instrument Approach Chart' I have dated 1954. The CR DF high level descent for RAF Merryfield had an initial overhead approach not below 12000 ft and went out on 115 degM to about 25 miles to 'half initial approach altitude plus 2000', then inbound on 285 degM with a check altitude of 3500 ft - and a min app. alt. of 1350 ft. Bearing in mind the field elevation was 145 ft, this looks like rather a useless procedure. Presumably you made the relevant calls to 'Merryfield Homer' on 104.94 Mc/s (this was long before the days of MHz) and switched to 'Merryfield Tower' on 102.42 Mc/s if you were fortunate enough to become visual!
Last edited by BEagle; 5th April 2010 at 22:51.
Joined: Jun 2001
Posts: 4,777
Likes: 9
From: Blighty
That DF procedure was being used as late at 1993 in anger. At EFTS Swinderby, it was our only approach aid - and we used it in anger frequently. For CAT A and B, the range outbound was 11NM, the minima 740' IIRC and although nothing like the ease of modern approaches, we got quite good at it because we flew it quite a lot. The students used to do a limited panel QGH as part of thier IFT - with about 40 hours total time. It was quite a challenge. When I wnet to CFS and had to fly my IRT on the Chippie using such a procedure after being 'dulled down' by hours flown on the Smiths MFS, I found it very difficult!
Joined: Nov 2009
Posts: 258
Likes: 0
From: Oxon
DME in the Hunters in 1956 was used for "Broadcast Control" interceptions when the close control frequency was jammed. For exercise purposes jamming was achieved by an open mike in the engine nacelle of a Lincoln thus making the GCI's instructions unreadable. A very high powered ground transmitter broadcast the target position. However as adjacent aircraft were still able to communicate one of a pair would tune in to a dme station eg Manston, and the other to somewhere else eg Tangmere. The lead called "Hayrake" and his wingman gave the distance. By using a cunning plotting device called the Wilson computer strapped to ones leg the two ranges could then be resolved as a fix and an intercept could be made on the estimated position of the target. It sounds simple but it finally relied on a visual intercept.
Another bit of kit fitted to Meteor F8s was Appendix which enabled homing on a jammer's transmission. Two needles crossed in the centre when you were flying directly towards or away from the target. To establish if it was higher or lower you did the first 90 degress of a slow roll and held it as long as possible when the instrument should indicate left or right, but in this case up or down. I can't remember if it was ever in Hunters.
Oh, the fun and games we day fighter pilots had in those days.
Another bit of kit fitted to Meteor F8s was Appendix which enabled homing on a jammer's transmission. Two needles crossed in the centre when you were flying directly towards or away from the target. To establish if it was higher or lower you did the first 90 degress of a slow roll and held it as long as possible when the instrument should indicate left or right, but in this case up or down. I can't remember if it was ever in Hunters.
Oh, the fun and games we day fighter pilots had in those days.
Joined: Apr 2010
Posts: 375
Likes: 65
From: Brisbane
One of the inventors passed away recently:
James Gerrand
And the airways museum has some good info:
The Australian DME System
James Gerrand
And the airways museum has some good info:
The Australian DME System
Joined: Apr 2006
Posts: 414
Likes: 0
From: On the Bay, Vic, Oz
Sorry markis10, but my first experience of the Australian DME "System" was in 1970 flying out of Archer Field, and I thought it was absolute rubbish. It really was a joke. The rest of the world had gone digital, whilst the DCA were extolling the virtues of "VHS tape". 
