Buccs in red flag.
The TFR was manually flown by the pilot following a director, actually the ILS glide slope indicator so if it failed or was jammed, the pilot would initiate a climb to whatever the crew considered prudent. In war over Russia we probably would have stayed at low level using the mapping radar (H2S) to predict the terrain.
It was the glide slope signal that I was recording and monitoring as an indication that the TFR was being spoofed. The idea was to look at the signal (on a paper chart recorder), convert it to height, mentally time delay it and compare it with the rad alt height that was also being recorded.
As it turned out, the design of the TFR made it inherently immune from interference, as any spoofed jamming return had to come in during the expected return window, and align with the antenna axis at that instant, which was a pretty narrow window. Although I wasn't involved with the ground equipment side, I think the jammer they'd come up with (supposedly based on intelligence from the Soviets) was a receiver to detect the TFR transmission pulse, with the jammer then transmitting a much stronger signal to try and get the TFR to assume the terrain ahead was higher than it really was.
I think there was a secondary requirement as a part of the trial to look at TFR reliability. Can't now remember what drove that, but I think it may have been related to an accident where there was suspicion that the TFR might have played a part.
There is a Buccaneer connection to this trip down memory lane, as my boss at the time had worked on the TFR fitted to a Buccaneer trials platform, as part of the TSR.2 programme (and I'd previously worked with two Elliot 920B suitcase computers salvaged from the scrapped TSR.2s for another lab project). Anyone know why they never fitted TFR to the Buccaneer in service?
As it turned out, the design of the TFR made it inherently immune from interference, as any spoofed jamming return had to come in during the expected return window, and align with the antenna axis at that instant, which was a pretty narrow window. Although I wasn't involved with the ground equipment side, I think the jammer they'd come up with (supposedly based on intelligence from the Soviets) was a receiver to detect the TFR transmission pulse, with the jammer then transmitting a much stronger signal to try and get the TFR to assume the terrain ahead was higher than it really was.
I think there was a secondary requirement as a part of the trial to look at TFR reliability. Can't now remember what drove that, but I think it may have been related to an accident where there was suspicion that the TFR might have played a part.
There is a Buccaneer connection to this trip down memory lane, as my boss at the time had worked on the TFR fitted to a Buccaneer trials platform, as part of the TSR.2 programme (and I'd previously worked with two Elliot 920B suitcase computers salvaged from the scrapped TSR.2s for another lab project). Anyone know why they never fitted TFR to the Buccaneer in service?
It's a long time ago but the Vulcan TFR was secured to the fore and aft axis. It looked for ground returns at, 8000yds.(?) so the beam angle was altered to give 8000 dependant upon the height set. Being secured to the F&A axis it could only see along Heading and the beam width was such that with any reasonable crosswind component, it could miss terrain anomalies along Track. As an Avionics Tech. I understood that TFR looked after the Heading terrain and H2S kept an eye along Track should there be any great difference between the two.
It's a long time ago but the Vulcan TFR was secured to the fore and aft axis. It looked for ground returns at, 8000yds.(?) so the beam angle was altered to give 8000 dependant upon the height set. Being secured to the F&A axis it could only see along Heading and the beam width was such that with any reasonable crosswind component, it could miss terrain anomalies along Track. As an Avionics Tech. I understood that TFR looked after the Heading terrain and H2S kept an eye along Track should there be any great difference between the two.
IIRC, the whole thing was a cylindrical self-contained unit, with the antenna, Tx, Rx and processing electronics all in the one assembly. There was an analogue computer in the processing section at the back that converted the angle and distance to height (did it also have a ground speed input?) and fed that out to the go up/go down display output.
I believe the beam was symmetrical, so would have been as narrow in azimuth as it was in elevation, partly due to it working up in in J band (which seemed an impossibly high frequency at the time) which enabled the antenna to be small enough to fit in the available space. That 2D (vertical axis only) profile meant that it couldn't detect obstacles slightly off-axis, just as you say, which was both a plus and a minus.
One reason (probably the primary one) that I think it was relatively immune from jamming was due to the way it correlated individual pulses and returns with the instantaneous measurement of the depression angle of the beam. To spoof it into producing a false terrain profile would mean getting a jamming pulse return into the antenna whilst it was off-axis, because of the constant bobbing motion. I believe that the Soviet intelligence that created the need for the trial I was involved with was based on an assumption that it may have been possible to inject such an off-axis spoofed pulse into the receiver, so fooling the processing into thinking that a ground return had been picked up with the beam at a higher elevation, where there shouldn't have been a ground return. My memory is hazy, but I think the receiver was gated to ignore returns beyond the maximum expected range at any depression angle (most probably that 8,000 yards you mention). As we found, even with as much power as we could create, together with a narrow beam horn on the jammer mast looking directly at the aircraft, the TFR receiver still always picked up the proper ground return rather than the jamming signal.
All the above could well be complete rubbish as my memory might well be flawed. I was a young Assistant Scientific Officer at the time, still in awe at being allowed to play with aeroplanes and get paid for it (my flying pay was a lot, about £5 per hour, or part of hour, flown at the time)! This was more than my regular pay. At that time I think my salary was around £500, so a few hours trials flying was a very worthwhile bonus. Truth be told, I'd have done the flying for free!
I recall being told that the RAFG Buccaneers weren't fitted with AAR probes. Airflow disturbance caused by the probe mean that when the screen wash button was pressed, the fluid would cover the whole windscreen very nicely. But without a probe, there would just be a small strip washed. To get over the problem, RAFG crews would apply a few rudder doublets whost the squirt was underway - job done!
Except that this caused additional fatigue which puzzled the engineers until the cause was established!
As I say, that's what I was told and might well be nonsense!
Except that this caused additional fatigue which puzzled the engineers until the cause was established!
As I say, that's what I was told and might well be nonsense!
RAFG Buccs did not generally have the probes fitted, with limited requirement for tanking in their usual profiles.
The issue of a "bootfull of screenwash" became more apparent in the later Sea Eagle operations which had a much greater need for windscreen cleaning due to the overwater operations. We had a number of issues with fin bolts and fittings that we couldn't identify a real reason for until we found out about the use of rudder. Some evidence was seen on OLM traces but the full picture wasn't available as there was no identifier placed on the tape when screen wash was used, and had we asked the aircrew to manually add one, they probably wouldn't have done it to the same extent.
Although it was binned with the subsequent withdrawal from service, we did some work on what modification would be most cost effective - revised fin fittings or a new windscreen wash system !
CAEBr
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BEagle, almost right.
RAFG Buccs did not generally have the probes fitted, with limited requirement for tanking in their usual profiles.
The issue of a "bootfull of screenwash" became more apparent in the later Sea Eagle operations which had a much greater need for windscreen cleaning due to the overwater operations. We had a number of issues with fin bolts and fittings that we couldn't identify a real reason for until we found out about the use of rudder. Some evidence was seen on OLM traces but the full picture wasn't available as there was no identifier placed on the tape when screen wash was used, and had we asked the aircrew to manually add one, they probably wouldn't have done it to the same extent.
Although it was binned with the subsequent withdrawal from service, we did some work on what modification would be most cost effective - revised fin fittings or a new windscreen wash system !
CAEBr
RAFG Buccs did not generally have the probes fitted, with limited requirement for tanking in their usual profiles.
The issue of a "bootfull of screenwash" became more apparent in the later Sea Eagle operations which had a much greater need for windscreen cleaning due to the overwater operations. We had a number of issues with fin bolts and fittings that we couldn't identify a real reason for until we found out about the use of rudder. Some evidence was seen on OLM traces but the full picture wasn't available as there was no identifier placed on the tape when screen wash was used, and had we asked the aircrew to manually add one, they probably wouldn't have done it to the same extent.
Although it was binned with the subsequent withdrawal from service, we did some work on what modification would be most cost effective - revised fin fittings or a new windscreen wash system !
CAEBr
It's a long time ago (about 50 years) since I fleetingly looked at one up close, so my memory might not be accurate. IIRC the reflector bobbed up and down through a small angle (6 degrees?), so changing the downward-looking angle of the beam, with the horn feed being fixed on a frame at the front. I thought it worked by correlating the measured angle of the beam (did it have a synchro on the reflector?) with the direct line distance, to produce what was, in effect, a 2D terrain profile of the ground ahead, but only on the aircraft horizontal axis.
IIRC, the whole thing was a cylindrical self-contained unit, with the antenna, Tx, Rx and processing electronics all in the one assembly. There was an analogue computer in the processing section at the back that converted the angle and distance to height (did it also have a ground speed input?) and fed that out to the go up/go down display output.
I believe the beam was symmetrical, so would have been as narrow in azimuth as it was in elevation, partly due to it working up in in J band (which seemed an impossibly high frequency at the time) which enabled the antenna to be small enough to fit in the available space. That 2D (vertical axis only) profile meant that it couldn't detect obstacles slightly off-axis, just as you say, which was both a plus and a minus.
One reason (probably the primary one) that I think it was relatively immune from jamming was due to the way it correlated individual pulses and returns with the instantaneous measurement of the depression angle of the beam. To spoof it into producing a false terrain profile would mean getting a jamming pulse return into the antenna whilst it was off-axis, because of the constant bobbing motion. I believe that the Soviet intelligence that created the need for the trial I was involved with was based on an assumption that it may have been possible to inject such an off-axis spoofed pulse into the receiver, so fooling the processing into thinking that a ground return had been picked up with the beam at a higher elevation, where there shouldn't have been a ground return. My memory is hazy, but I think the receiver was gated to ignore returns beyond the maximum expected range at any depression angle (most probably that 8,000 yards you mention). As we found, even with as much power as we could create, together with a narrow beam horn on the jammer mast looking directly at the aircraft, the TFR receiver still always picked up the proper ground return rather than the jamming signal.
All the above could well be complete rubbish as my memory might well be flawed. I was a young Assistant Scientific Officer at the time, still in awe at being allowed to play with aeroplanes and get paid for it (my flying pay was a lot, about £5 per hour, or part of hour, flown at the time)! This was more than my regular pay. At that time I think my salary was around £500, so a few hours trials flying was a very worthwhile bonus. Truth be told, I'd have done the flying for free!
IIRC, the whole thing was a cylindrical self-contained unit, with the antenna, Tx, Rx and processing electronics all in the one assembly. There was an analogue computer in the processing section at the back that converted the angle and distance to height (did it also have a ground speed input?) and fed that out to the go up/go down display output.
I believe the beam was symmetrical, so would have been as narrow in azimuth as it was in elevation, partly due to it working up in in J band (which seemed an impossibly high frequency at the time) which enabled the antenna to be small enough to fit in the available space. That 2D (vertical axis only) profile meant that it couldn't detect obstacles slightly off-axis, just as you say, which was both a plus and a minus.
One reason (probably the primary one) that I think it was relatively immune from jamming was due to the way it correlated individual pulses and returns with the instantaneous measurement of the depression angle of the beam. To spoof it into producing a false terrain profile would mean getting a jamming pulse return into the antenna whilst it was off-axis, because of the constant bobbing motion. I believe that the Soviet intelligence that created the need for the trial I was involved with was based on an assumption that it may have been possible to inject such an off-axis spoofed pulse into the receiver, so fooling the processing into thinking that a ground return had been picked up with the beam at a higher elevation, where there shouldn't have been a ground return. My memory is hazy, but I think the receiver was gated to ignore returns beyond the maximum expected range at any depression angle (most probably that 8,000 yards you mention). As we found, even with as much power as we could create, together with a narrow beam horn on the jammer mast looking directly at the aircraft, the TFR receiver still always picked up the proper ground return rather than the jamming signal.
All the above could well be complete rubbish as my memory might well be flawed. I was a young Assistant Scientific Officer at the time, still in awe at being allowed to play with aeroplanes and get paid for it (my flying pay was a lot, about £5 per hour, or part of hour, flown at the time)! This was more than my regular pay. At that time I think my salary was around £500, so a few hours trials flying was a very worthwhile bonus. Truth be told, I'd have done the flying for free!
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This vid, admittedly of Buccs over the sea, gives some idea of how low you can go! Music is pretty good too.
The 'low' stuff starts at about the 2:15 mark.
The 'low' stuff starts at about the 2:15 mark.
Last edited by BANANASBANANAS; 26th Nov 2023 at 06:47.
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The plumbing was there, but not all aircraft had the probe fitted. It was a fixed, non-retractable probe, so actually fitting it wasn't a great deal of work.
I am fairly sure that the TFR range was 9,000 yds, TFR on the Vulcan (when I worked on Akrotiri Wing) was a very unserviceable beast. It occasionally gave a fly down when it should have been up. (or so the crews reported ). It has an odd cooling system. Outside air was passed into the pod and passed over the electronics directly, OK when it was dry. Having poured the water out of a removed pod after a sortie over Greece in severe wet conditions, I can confirm this state. I later went to work for MEL and was surprised just after I started to find that they provided manufacturer support, having walked past the test section.
I was just starting my 300ft TFR check flight in March 1979 when we had a 'main warning - amber' with various annoying lights illuminating. Followed closely by the check captain asking the AEO what the heck was going on! Back came the reply - we'd lost the entire no.3 busbar! So we diverted to RAF Leeming and repaired to the OM bar whilst a bus came up from RAF Scampton to collect us. It later transpired that something hadn't been properly connected in the power compartment and that the buffeting at low level shook it loose!
Oh well, tried again a couple of days later, but the TFR was U/S. Then came Double Top and Giant Voice, so it was nearly a year before I was finally able to complete TFR training!
Oh well, tried again a couple of days later, but the TFR was U/S. Then came Double Top and Giant Voice, so it was nearly a year before I was finally able to complete TFR training!
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This vid, admittedly of Buccs over the sea, gives some idea of how low you can go! Music is pretty good too.
The 'low' stuff starts at about the 2:15 mark.
https://youtu.be/lteL18wd15Y
The 'low' stuff starts at about the 2:15 mark.
https://youtu.be/lteL18wd15Y
King's of Leon: Sex on Fire.
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Thought police antagonist
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Nice little cafe there as well.
I fly at Tatenhill fairly regularly and I will be there next week - I don't know if the folk I see there know what is going on with that particular Bucc, but it looked very good last time I saw it in its desert camouflage sitting on the South side of the runway. It used to be on the North side when it came from Brunt (I think) but the new cafe building has been delayed a bit so maybe that it was why it moved to the other side of the airfield.
If I can find any useful info when I am next there, I will share it with you all.
If I can find any useful info when I am next there, I will share it with you all.
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I fly at Tatenhill fairly regularly and I will be there next week - I don't know if the folk I see there know what is going on with that particular Bucc, but it looked very good last time I saw it in its desert camouflage sitting on the South side of the runway. It used to be on the North side when it came from Brunt (I think) but the new cafe building has been delayed a bit so maybe that it was why it moved to the other side of the airfield..
Michel's lab on YouTube has done a few teardowns of Bucc avionics recently if you're interested. Also VC10 and SeaKing plus a bunch of other bits.
