Moving map flight visualiser from the 60's

[Akubra]

Hi all!
Has anyone seen one of these or the like before?
Searching the net turned up nothing so I thought I would post it up here.
Made around the early to mid 60's, the pathfinder uses clear and pre printed strip charts. The pre printed ones are for inter-US destinations only. The 6 foot clear ones are used for tracing over maps and have a printed distance grid and boxes for the pertinent information needed.
It runs on 2 D-cells and can handle speeds up to 250 MPH.
Thompson Designs Inc seem to be no longer around, maybe they were brought out or just faded away after the cold war? I just cant find anything...
Any info would be great!
Regards, Stephen.

http://i119.photobucket.com/albums/o131/acubra/Thompson%20Flight%20Visualizer/thompson-flight-visulizer.jpg

http://i119.photobucket.com/albums/o131/acubra/Thompson%20Flight%20Visualizer/thompson-fine-tune.jpg

http://i119.photobucket.com/albums/o131/acubra/Thompson%20Flight%20Visualizer/thompson.jpg

[reynoldsno1]

I remember flying on a Silver City Airways DC3 from Lydd to Le Touquet in about 1960. I were only a lad, but I do recall the moving map display in the cockpit. It had an actual ink trace and I presume was powered by Decca (which I used myself many years later)

[Akubra]

Thanks reynoldsno1!
Searching Decca revealed an interesting thread right here on Pprune. http://www.pprune.org/archive/index.php/t-384288.html
BOAC's comment did give me a chuckle. :) Imagine seeing that!

The thread also pointed me to this site which has lots of information about Decca and its systems.
Decca Navigator - Airborne Receivers and Indicators (http://www.jproc.ca/hyperbolic/decca_rx_ind_airborne.html)
I see they had a portable unit called the "Mini DECCA" Mk-18 but that was experimental and relied on a signal for positioning. I'm thinking their very first device (a plotter) was closer to the lines on what I have here.
Cheers, Stephen.

[Fareastdriver]

That's nothing to do with Decca as there wasn't any Decca coverage in the USA. It looks like a powered map that gives you a guide to where you are if you dial in the right speed and any change of heading with the compass thing. Should you, by some miracle, put in the right information it might even be able to tell you where you are going.

[Groundloop]

The Decca system used by BEA in Tridents can be seen here:-

Photos: Hawker Siddeley HS-121 Trident 3B Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/BEA---British/Hawker-Siddeley-HS-121/0643499/L/&sid=fae9c37304bf4661a5439f2e489d3b00)

[Krakatoa]

Not Decca on a Trident. A self contained Doppler system with moving map.

[Fareastdriver]

The trident is fitted with doppler. A trick with those was that if you were flying a single track for miles, ie the Atlantic, is was not neccessary to have a map.
You selected the track on the doppler, put a chinagraph spot under the pen on the backplate and turned left/right to keep the pen on the spot.

Simple.

Information for those that have not used Decca roller maps. The map can never be true to scale because the Decca signals are curved and the map requires straight inputs to roll it up/down and the pen left/right. The result is that the map gets more distorted the further one gets from the master and slaves station. The London area would look reasonably normal but the South of France would look like a crushed sausage. To have a reasonable presentation would require dozens of chains and VOR was a lot simpler.

They had a go at creating a topographically correct map but it was impractical. I remember flying a trials unit that gave a digital readout instead of deccometers but it was too prone to lane shift and faded away.

Decca was OK when used by aircraft and ships in the marine envirionment. SAR, oil support helicopters used it until the end and then it closed on the 31st Mar 2000. No more would there be a runaway map pouring yards of paper over the cockpit floor.

[merlinxx]

Bloody Decca Nav, had on our Comets, aeroplane was too fast for the Decca turrets. Not allowed to have the doppler like mainline's Ground Grippers:{

[avionic type]

We had the Decca nav system on our B.E.A. 701 Viscounts in the 50s and 60s but for the life of me I can't remember if it were fitted to the 800s
I still have a map reel as fitted to the Trident somewhere

[JW411]

Thank God we didn't persevere with Decca. It really was designed as a ship's navigation system and designed to work at the speed of a ship. It could be pretty erratic at times. Does anyone else remember having to fit all the keys in exactly the correct order into the turret. I seem to remember that each key had a 3-letter designation (like "JJK" for example) and woe betide you if you got them in the wrong order.

I did a year seconded to BEA on the Viscount 802/806 in 1964 and I can't remember if they were Decca equipped either. On balance, I think they were.

I can remember doing some trials at Larkhill on Salisbury Plain to see if we could use Decca for "blind dropping" (of troops and/or equipment). We selected Decca chains that gave us a good track lane through the drop zone and another chain that gave another lane at 90 degrees or so in order that we could compute a release point making due allowance for wind effect (CARP - Calculated Air Release Point).

After a bit of practice we were getting an accuracy of 200 yards but there were just too many imponderables to make the system reliable.

Just imagine what we could have done with GPS and a Garmin 430 instead of a single Doppler and a Decca?

For that matter, just imagine what Bomber Command could have achieved even with a TomTom!

[mcdhu]

Yes.........chart change - difficult. Chart and chain change - very difficult!!

[Agaricus bisporus]

It really was designed as a ship's navigation system

I think you'll find Decca grew from the wartime Gee blind bombing system, so its origins were very much aviation based.

[merch]

I think you will find that Gee developed into LORAN which uses time difference between the received signals from two (or more) transmitting stations. Although Gee was developed for aircraft, LORAN was primarily used by ships.

Decca was originally used for the D Day landings and is based on the phase difference of received signals and again primarily used by ships.

Merch

[Akubra]

Seems they did have a Decca chain set up in the New York area for use by the New York Airways Helicopter Service. It was also later used by the FAA for trials.
Interesting to read about the fate of Decca in the US and some reasons why it was not adopted.
Here is a link to google books who have a 1960 New Scientist on archive.
New Scientist - Google Books (http://tinyurl.com/2eulg5c)

[Fareastdriver]

The Decca Navigation Company's hospitality was legendary. After a factory visit you would be bundled into a bus with all the windows papered over. At the front would be a large scale moving map display with the streets of London. You would follow your progress until it stopped by a black square labelled PH. Then you were let out and you found yourself in a pub car park just about to be herded in for a slap up lunch and loads of beer.

The pre-Xmas parties at Decca House were something else as well.

[Krakatoa]

For what it is worth the BEA Viscount 800 were fitted with Decca.

[FLCH]

Didn't Spitfires have Decca's ?

Decca Decca Decca !!! ;)

[forget]

I'm surprised that no one has recognised this from wayback but, with a bit of luck, it was the only one ever made. You're far better off being absolutely certain that you're lost rather than rely on Thompson Designs Inc - and think that you're not. :hmm:

Still, a nice thing to have, on the ground.

[tonytech2]

Eastern Air Lines fitted its Air Shuttle DC-9's with Decca Nav around 1968. It was called "Sky Guide". Main problem seemed to be the number of cartridges needed. Also idea was to bypass airways going more directly - In crowded Northeast corridor from Boston to New York to DCA area it was not really practical. I believe it was also fitted to the French STOL demonstrator we flew for a while with Scott Crossfield as Project Manager.

[petermcleland]

The HARCO fitted to BEA's Super 111s was Decca powered and was great for the German Internals operations out of Templehof and down the three "Corridors" to the various German destinations. I liked it very much and it included a moving map. The waypoints for each sector were built into a "Turret" and there was a little suitcase full of turrets...You just checked the Turret Number on your Plog, got that Turret out of the little case and plugged it into the centre console. You could lock the autopilot onto it and it would fly you all the way. Large angle turning points would be "Shortcut" to perfection with a turn before the point which rolled out exactly on the outbound track. A jolly handy piece of kit for a two crew aircraft. The relevant VORs and NDBs would all be tuned by the co-pilot and their needle on the RMI checked as HARCO did the turn...Harco was always spot on.

[Flightwatch]

I too used Harco on the BEA/BA S1-11s for 14 years on the IGS and within Western Europe. 90% of the time it was great and one could navigate safely within a couple of hundred yards of the corridor edges trying to avoid the Cbs which inevitably lay across the centre of the airway whilst the American controllers were frantically giving you 60 degree turns towards the centre line to avoid a visit by a Mig.

The one problem was that it wasn’t unknown for the machine to “jump” a lane thereby putting you a few miles to the left or right of your desired track. It was therefore necessary to get a confirmatory fix passing the corridor entry beacons at Brunkendorf, Hehlingen or Mansbach to make sure it agreed with your actual position. Mansbach proved its effectiveness well as it was a localiser which you tracked inbound or outbound to for many (100?) miles and when locked on to Harco the needle would stay in the middle the whole way.

It also had the ability for you to enter a ghost beacon – usually the end of the runway – thereby giving you your distance to run, this in the days before either the 1-11 or the ILS had a DME and it greatly aided the inevitable competition as to who could keep the throttles closed from top of descent to as close as possible to the runway, 500’ was around the norm. No stabilized approach criteria in those days.

I left the S1-11 fleet in 1984 and I gather that Harco was soon after removed from the aircraft, the space where the map used to be being used to hang up the approach plates on a bulldog clip instead.
I don’t know why it was removed but think it might have had something to do with the closure of the chains or possibly the cost of maintaining the equipment.

Many recreational sailors used Decca as well in a moving map form – it was a toss up as to whether to invest in a Decca or a GPS, in it’s infancy in those days. Of course ultimately the GPS won and the once proud owners of the Decca navigators were left with a scrap iron box.

I also flew the 802/806x Viscount and can confirm that it was originally fitted with Decca although by the time I got to it in 1967 it had been removed in our aircraft along with the cockpit air conditioner which made flying in the summer bearable.