Global Aviation Magazine : 60 Years of the Hercules
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Don.
Out near Europa Point. Almost in Spanish airspace but a good pic.
Coff. The Decca roller map was used mainly for low levels and (for Smudge) it was used for the Berlin corridor. I never used it on the Herc but when the Doppler A/A box failed it was swapped over with the roller map box.
Out near Europa Point. Almost in Spanish airspace but a good pic.
Coff. The Decca roller map was used mainly for low levels and (for Smudge) it was used for the Berlin corridor. I never used it on the Herc but when the Doppler A/A box failed it was swapped over with the roller map box.
Doug,
ah the famous Doppler box swap. Did many a one for the Nav. My extensive tech training was not wasted ! I have swopped the IRCM box as well.
ah the famous Doppler box swap. Did many a one for the Nav. My extensive tech training was not wasted ! I have swopped the IRCM box as well.
Coff,
I posted the pic of the Decca Nav so if it has disappeared from the thread let me know and I will try to post it again.
I posted the pic of the Decca Nav so if it has disappeared from the thread let me know and I will try to post it again.
Smuj
I'm reluctant to comment, especially having had the pleasure of meeting Dougie for the first time at A***** C******'s 70th birthday bash on Saturday! Dougie with his 11 tours and me with my paltry 2, but why had your nav even switched the Loran on going to Gatow?
The only excuse I can think of is that maybe the next task from Gatow was to be across the North Atlantic without routing via Lyneham. I always found Loran C dead easy to use and on the odd occasion after losing one chain and before successfully gaining the other ( perhaps due to atmospherics or something ), I sat back and enjoyed the latest drink that the ALM gave me!
Decca, particularly the flight log, what a waste of space! I only ever used it while attached to JATE as it was good for track alignment in high-level parachute drops.
The only excuse I can think of is that maybe the next task from Gatow was to be across the North Atlantic without routing via Lyneham. I always found Loran C dead easy to use and on the odd occasion after losing one chain and before successfully gaining the other ( perhaps due to atmospherics or something ), I sat back and enjoyed the latest drink that the ALM gave me!
Decca, particularly the flight log, what a waste of space! I only ever used it while attached to JATE as it was good for track alignment in high-level parachute drops.
Brian,
I have previously recounted a blind drop trial, with paras, with Decca that was not a success ! The trial was discontinued.
I have previously recounted a blind drop trial, with paras, with Decca that was not a success ! The trial was discontinued.
Last edited by ancientaviator62; 19th Apr 2016 at 10:27.
Reposted the pic of the Decca Flight Log which did not last long on the 'K'.
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Decca
This aid was definitely for ships or just taxying in fog. At 25k feet we would blithely commit the "hooligans" to a HALO jump based on Decca before GPS came along. One snag with Decca was that at altitude (it was a surface aid) it used to slip lanes so just before releasing the brave boys in IMC the Nav would call Lyneham for a radar fix to confirm his position. We flew down a purple line mostly and called the lights on a red line crosscut. It worked quite well but there was no Decca where you needed it. The homemade chart shows where Fox Covert DZ should be.
Brian 48. Good to see you at the do. I wrapped Art's present in a cut off flying suit leg to remind him of what he did to mine in Akrotiri!
Brian 48. Good to see you at the do. I wrapped Art's present in a cut off flying suit leg to remind him of what he did to mine in Akrotiri!
Ref Posts 4272 & 4278
Dougie an old photo of you in pre- Omega days. You look wonderfully in control.
Reference your comments about straying off track in N.Atlantic and being violated. I can recall only two extreme tracking errors. One a VC10 and the other a C130. IIRC the VC10 navigator was flying with the compasses set to Directional Gyro(DG) and had a South Latitude (instead of North) selected on the Earth Rate Drum. The Herk nav used Variation instead of Grivation to correct the navigation computers. These mistakes introduced large heading errors. Luckily, both were westbound and the errors turned the a/c north towards Greenland. I believe the errors became apparent when a very large CB in the shape of Greenland was seen on the CCWRs.
Track keeping on the C130 in my day (until 1995) was a lot easier when the magnetic compass was switched to Gyro (DG) and gyro/grid technique was flown. The accuracy of the magnetic compass, although swung accurately to .1degree, depended largely on the accuracy of the magnetic variation and how adept you were in keeping the local variation updated as you stooged along. The variation lines plotted on the charts are a mean and change position slowly with time as does the position of magnetic north. Local variation can also be radically different from that printed on the chart. In the DG mode there is no magnetic influence on the compasses and hence no magnetic error.
The introduction of Omega and its digital computer, allowed the Azimuth of the Sun, (or other heavenly bodies) to be computed in degrees True to within an accuracy of .1 degrees. The a/c heading , using the periscopic sextant, aligned on the bodies azimuth, could be read to about the same accuracy. With the appropriate corrections to convert this to a Grid heading, this reading would be compared to the C12 DG readout. Any wander of the gyro from the correct reading would be removed and a gyro wander rate established which would then be tuned out, hopefully to zero by altering the C12 latitude drum (Earth Rate). It was possible, during the flight, to get the DG wander rate less than 1 degree/hour.
Astro shots were also made more accurate in DG mode because there was no ‘hunting’ of the C12 as it annunciated to refine the magnetic heading. (This reduced heading acceleration error. For example a turn of .5degrees at 300kts would give an astro error of 8nm) It was normal practice to go to DG, when not flying gyro, whilst shooting astro to alleviate this error.
The Doppler drift and G/S, I believe were quite accurate, disregarding surface motion of the waves, as was the Along/Across (AA) track computer. The A/A computer could be fine tuned trackwise by setting a false track to compensate for the track error You could not do anything to the Distance to Go counters to make them more accurate but then the most important thing was correct tracking. The Latitude/Longitude computer was a disaster and could rarely be trusted, it spent most of its time running away in any direction at about 1000kts!
Before the introduction of Omega the azimuths of Stars/Planets had to be laboriously extracted from the Sight Reduction Tables or from graphs where it was difficult to get the required accuracy and you very often used to introduce errors into an otherwise accurate gyro. It was very laborious and I only did it when strictly necessary
(The alignment of the sextant on the a/c centreline was always checked before a major navigational routes by checking that the fin of the a/c was in the right place!!!: 180.4 degrees if I remember correctly).
Reference your comments about straying off track in N.Atlantic and being violated. I can recall only two extreme tracking errors. One a VC10 and the other a C130. IIRC the VC10 navigator was flying with the compasses set to Directional Gyro(DG) and had a South Latitude (instead of North) selected on the Earth Rate Drum. The Herk nav used Variation instead of Grivation to correct the navigation computers. These mistakes introduced large heading errors. Luckily, both were westbound and the errors turned the a/c north towards Greenland. I believe the errors became apparent when a very large CB in the shape of Greenland was seen on the CCWRs.
Track keeping on the C130 in my day (until 1995) was a lot easier when the magnetic compass was switched to Gyro (DG) and gyro/grid technique was flown. The accuracy of the magnetic compass, although swung accurately to .1degree, depended largely on the accuracy of the magnetic variation and how adept you were in keeping the local variation updated as you stooged along. The variation lines plotted on the charts are a mean and change position slowly with time as does the position of magnetic north. Local variation can also be radically different from that printed on the chart. In the DG mode there is no magnetic influence on the compasses and hence no magnetic error.
The introduction of Omega and its digital computer, allowed the Azimuth of the Sun, (or other heavenly bodies) to be computed in degrees True to within an accuracy of .1 degrees. The a/c heading , using the periscopic sextant, aligned on the bodies azimuth, could be read to about the same accuracy. With the appropriate corrections to convert this to a Grid heading, this reading would be compared to the C12 DG readout. Any wander of the gyro from the correct reading would be removed and a gyro wander rate established which would then be tuned out, hopefully to zero by altering the C12 latitude drum (Earth Rate). It was possible, during the flight, to get the DG wander rate less than 1 degree/hour.
Astro shots were also made more accurate in DG mode because there was no ‘hunting’ of the C12 as it annunciated to refine the magnetic heading. (This reduced heading acceleration error. For example a turn of .5degrees at 300kts would give an astro error of 8nm) It was normal practice to go to DG, when not flying gyro, whilst shooting astro to alleviate this error.
The Doppler drift and G/S, I believe were quite accurate, disregarding surface motion of the waves, as was the Along/Across (AA) track computer. The A/A computer could be fine tuned trackwise by setting a false track to compensate for the track error You could not do anything to the Distance to Go counters to make them more accurate but then the most important thing was correct tracking. The Latitude/Longitude computer was a disaster and could rarely be trusted, it spent most of its time running away in any direction at about 1000kts!
Before the introduction of Omega the azimuths of Stars/Planets had to be laboriously extracted from the Sight Reduction Tables or from graphs where it was difficult to get the required accuracy and you very often used to introduce errors into an otherwise accurate gyro. It was very laborious and I only did it when strictly necessary
(The alignment of the sextant on the a/c centreline was always checked before a major navigational routes by checking that the fin of the a/c was in the right place!!!: 180.4 degrees if I remember correctly).
Doug,
the blind drop trial I referred to was abandoned because of lane jumping.
And yes we were dropping the SAS from 25000ft too. Boscombe normally monitored the trials but the powers that be wanted this done using Decca alone because if done for real we would not have radar assistance nor would we be talking to anyone !
the blind drop trial I referred to was abandoned because of lane jumping.
And yes we were dropping the SAS from 25000ft too. Boscombe normally monitored the trials but the powers that be wanted this done using Decca alone because if done for real we would not have radar assistance nor would we be talking to anyone !
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IIRC Snoopy had a Ferranti INS in the van in the cargo hold that the Met Office boffins would use to get accurate wind data after post flight number crunching. Some time in the early 1990s this was replaced with a Honeywell laser ring gyro INS, and the nav had a feed. Soon after this was joined by a NAVSTAR xr(?) 5 GPS. Again mainly for scientific use, the nav was able to enter way points and use it for basic navigation. Unfortunately I have had a look through the old albums and I don't have a photo of the nav station.
Late 70's / early 80's ... I was on a 6A call out taking the water based hooligans and one of their ribs across the pond, doppler was being a pig and the LORAN then failed, just as we hit some crap weather so preventing astro ... Nav soon stated he was "unsure of his position" and suggested a diversion as things would only get worse .. not an unreasonable suggestion ... ALM relayed this to the passengers, and just as we started to negotiate with Gander ATC a piece of paper with a very accurate position and time was handed to the Nav.... hooligans had fired up some equipment which included GPS ... this continued every 10 minutes for the next few hours as we headed West !! On chatting to their leader he simply said he only had clothes for hot places and he was buggered if he was going to Kevlavik in the winter !! It was some years later that we got anything like decent Nav kit !!
I also vaguely recall ( and I think it was Dougie) doing a "Bulls Eye" competition with the nav using a GPS cobbled together from external bits that involved the aerial sticking out of the very pistol hole !!... at one stage the on board judge gave the instruction to switch off the doppler to simulate failure ... which was followed by a comment along the lines of ... "switch it off ?? ******* thing has not worked since start up!!"
I also vaguely recall ( and I think it was Dougie) doing a "Bulls Eye" competition with the nav using a GPS cobbled together from external bits that involved the aerial sticking out of the very pistol hole !!... at one stage the on board judge gave the instruction to switch off the doppler to simulate failure ... which was followed by a comment along the lines of ... "switch it off ?? ******* thing has not worked since start up!!"
DeanO
I remember that apparently the VC10 had departed another UK RAF base following a night stop and the nav' said that he had not been able to sleep due to the noise all night from the summer ball.
The Herc' nav, although 'E' catted, was complimented for admitting to his error and last I heard he got to the first 'scrambled egg' rank. Top man! We did a Nairobi detachment together when an RAF party was based there to assist in the uplift of loads of pongoes after their period of training in Kenya. I, as a Flt Lt was i/c and he as a Fg Off was my No2 - talk about blind leading the blind, thank goodness we had a MAMS Fg Off who knew about discip' and charging if required!
Omega
Tankertrashnav has posted on another thread, how when his Victor Tanker was one of a pair escorting some Jaguars ( IIRC ) across the pond their nav aids didn't work due to calm sea and astro was out and the single seat guys were giving the four Victor navs fixes from their kit.
The Herc' nav, although 'E' catted, was complimented for admitting to his error and last I heard he got to the first 'scrambled egg' rank. Top man! We did a Nairobi detachment together when an RAF party was based there to assist in the uplift of loads of pongoes after their period of training in Kenya. I, as a Flt Lt was i/c and he as a Fg Off was my No2 - talk about blind leading the blind, thank goodness we had a MAMS Fg Off who knew about discip' and charging if required!
Omega
Tankertrashnav has posted on another thread, how when his Victor Tanker was one of a pair escorting some Jaguars ( IIRC ) across the pond their nav aids didn't work due to calm sea and astro was out and the single seat guys were giving the four Victor navs fixes from their kit.
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Nav Kit
I bet Smuj regrets asking if any of this stuff worked properly. The MOD in its ignorance never replaced a Nav system until it had been finally switched off. Those in the right place when "Hand held GPS" modules came out had the edge and the American BX was the place to pick them up. The average G.I. soon found that they were too complex for the average grunt so you could get one for less than a hundred bucks in the Ft Bragg BX. A bargain in those days but they needed to be placed in a paper cup and stuck to the window frame with bodge tape to get a signal.
Just before Loran disappeared I was being checked eastbound across the pond and no "external aids" were permitted. In mid ocean the SS2 Loran chain went off the air. There was no warning published and we were under total overcast. Normally I would have emulated Brian 48nav and waited for SL3 to come up but Nav activity had to be maintained. The only thing remaining was a Consol count. A kit left over from the war and you needed to count 60 dots and dashes for a position line. Well I counted the Bushmills (MWN) broadcast and tuned in Ploneis (TRQ) to do it again when the checker said "I'm not living through that again, take your GPS position from the paper cup and we'll call it "B" maintained".
Just before Loran disappeared I was being checked eastbound across the pond and no "external aids" were permitted. In mid ocean the SS2 Loran chain went off the air. There was no warning published and we were under total overcast. Normally I would have emulated Brian 48nav and waited for SL3 to come up but Nav activity had to be maintained. The only thing remaining was a Consol count. A kit left over from the war and you needed to count 60 dots and dashes for a position line. Well I counted the Bushmills (MWN) broadcast and tuned in Ploneis (TRQ) to do it again when the checker said "I'm not living through that again, take your GPS position from the paper cup and we'll call it "B" maintained".
Never used Decca in an aeroplane, but as part of the Towers course, in 1965 I spent 2 weeks in one of Aunty Betty's war canoes, HMS Rhyl. As part of the cruise (it was, see later). The somewhat idiosyncratic captain decided that Iain A-R and I should stand watch as Second officer of the Watch. So I am "navigating" this ship up the East Coast en route to HM opening the Forth Road Bridge, and the Decca says I am in Newcastle High Street. The "cruise" - oh yes, a week in Stockholm, and as Iain always said "they don't dance like that in Pinner"
Wow, thanks all who have enlightened me on the "Nav kit"! Especially Dougie M. As an ex GE I can't speak for those triangular (and funny) charts you seem to have a grasp of, but I remember doing a lot of box changes to keep the Nav happy. Ahhh, at least it kept me awake eh ?
2y's UR, 2y's UB, ICUR 2 Y's 4 me !
Smudge
2y's UR, 2y's UB, ICUR 2 Y's 4 me !
Smudge
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Airdrop
K3K3
I think that Dragartist might have a few pithy remarks about the rigging of heavy loads in the USAF. We used to have a photo in the low level office labelled: A bad day for 47AD.
I think that Dragartist might have a few pithy remarks about the rigging of heavy loads in the USAF. We used to have a photo in the low level office labelled: A bad day for 47AD.