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Hallo I do not know as far after reading the posts on the forum now for a while, I assume that one white area of many modelers is the radio installation. For all WW2 a/c types. I had the chance to meet in 2009 a person in charge of the Signal museum. He took us after an airshow to the museum and explained every item there. Starting from early Huricans, Avro Ansons to the highly sophisticated Rebecca or H2S. To give you an idea, just read my summary. Happy modelling RAF Signals Museum Henlow 13th July 2009 Airborne Radio and Navigation Equipment All the equipment mentioned here can be seen in the album RAF Signals Museum Henlow A/C on early days was equipped with a transmitter only, so that aircraft flying over the German lines could send Morse back the artillery position. The transmitter was fitted in the aircraft with a long aerial. In most cases the pilot had to lean out of the aircraft to use the trailing aerial and use the Morse Key which was mounted on the side of the fuselage. The early days they had just the transmitter no receiver. The transmitter 1101 was used. Previous to that they used to drop a streamer (long strip of linen with weight), as shown, with the information written on it. Or they used also pigeons. Towards the end of WWI they were experimenting with transmitter and receiver. This was at about the war’s end at about 1918. They were doing tests dated at the logbook from June 1918. It shows successful as well as unsuccessful tests. The aircraft used as a flying test bed was a Bristol Fighter. The crew did two way tests. This equipment was improved and implemented and finally used until the 1920s, but we did not know that this early equipment was used even at the beginning of WWII. In 1920 this was already phased out equipment. The receiver is shown from all sides TF and transmitter T21C. The boxes on the shelf of the Avro Anson are identified as the transmitter T21C, the receiver R1082. The two other boxes must have been a power unit, a storage box for coils for different frequencies. They are marked with letters according the wave band. The other configuration is the transmitter T1083 and the receiver R1082. This was most common in the early days of WWII. The standard equipment for the RAF was the receiver R1155 and the transmitter T1154: The coloured knobs are for the different frequencies. There are two power supplies; the main power supply is low voltage for the receiver and some for the transmitter. The high voltage power supply is for the transmitter. The intercom box A-1134 was used on multi-seat aircraft, to communicate with the crew members on all stations on the a/c. The winch for a trailing aerial is placed in the radio compartment. The fixed aerial is placed on the airframe. The long aerial was necessary for radioing back from over Germany. The space between aircraft must have been controlled to prevent an accident with these long aerials. Of course even before landing, the winch had t o be operated to get the trailing aerial in. Fighter of early days as Spitfire and Hurricane and Gladiator from 1939 had a simple transmitter, the TR9, very basic, the receiver also very basic, not very good. All this was accommodated in the fuselage, where a hatch gave access. This equipment worked on the frequency of 4 - 6 MHZ. You need quite a long antenna for these frequencies but in a fighter aircraft you do not have space for a long antenna. The antenna was very inefficient. The range A/A was about 8km. The range air to ground was about 50km. This equipment was not very good. They had a big problem. In the Battle of Britain since the communication was very poor. They used to fit ground relay station where action could happen. The messages where transmitted from the relay station by land line to the controllers. This was the time of build up the Battle of Britain. At the same time they tried to introduce a VHF system. The pilot in the Battle of Britain had no radio equipment in his cockpit. He only had a big knob connected by Bowden cable to the radio set in the fuselage. The Swordfish receiver R1116a had a matching transmitter T1115 (we don’t have one at Henlow!) , equipment of this type for single person aircraft, would be pre-tuned so would need little adjustment when flying. No RAF aircraft was equipped with this transmitter and receiver. VHF was very efficient. The British 4 channel VHF system prototype was shown. Even the full size ¼ wave antennas could be seen. The range increased air to ground increased from 50 to over 200 kilometers. British industry could not build this equipment in quantity. Therefore American industry produced this. The Americans took the design and developed a new version. TR unit 1143 was used and it fitted at the same place in the fuselage. After the battle of Britain all the squadrons were fitted with this new VHF equipment. By 1942 all RAF squadrons in Britain was equipped with this VHF communication system. A disadvantage of the VHF: line of sight range, for short and medium range communications, maybe over sea since the horizon curves away, communications could be lost. That’s why the may have kept also HF for long distance communications. VHF signals propagate over line of sight. The weather condition does not influence VHF. The VHF equipment had four channels. The control unit for the pilot had five switches. This was much better, than the mechanical control as in the old HF equipment. Here the VHF receiver, R1147, was shown from 1947. When the equipment was introduced to the FAA is not sure. But it was believed to be towards the end of WWII. ASV (Air to Surface Vessel) indicator is shown. Radio compartment of the Lancaster GEE indicator as shown on the photo GEE was the main navigation equipment which was used. The black ones are used in the A/C. The grey ones are for training on the ground. This one is now working, we restored it. On the screen you have ground beacon responses, and calibration markers. With the calibrator you can turn the markers in different positions and to fine tune them. You actually could track the ground markers. With using the complicated hyperbolic diagram you could figure out your definite position. Three ground stations were involved. One master station and two slave stations were used. They used GEE to get on the site quite well. GEE was passive. The size of GEE box: 23/23/40. H2S First navigate to close to the target with GEE and at 10 km to target, switch on H2S. Since H2S could be located by German D/F ground stations, the British were reluctant to use the equipment in the early days as the H2S magnetron microwave was hard to destroy by detonator on the aircraft and they did not want the Germans to have a working sample from a crashed aircraft. The tail warning radar could be detected by night fighters and they could home in on the bomber and therefore it was not as good as had been hoped. An infra-red system was later tried. The other equipment was for the final adjustments over the target zone. The radar shows you the target but it does not take care of wind speed and so on. The British bomb sight allowed making final adjustments with parameters like speed, IAS, wind speed, altitude above the target, A/C bombing angle and many others. The frame shown is in a transit frame, not having been installed in an A/C. Rebecca The airborne Rebecca interrogator transmitted 300 3-4 μSec pulses per second on a frequency between 170 and 234 MHz. Upon receiving this signal the mobile, ground based Eureka rebroadcast the pulses on a different frequency. This rebroadcast signal was received by two directional 'Yagi' array aerials on the aircraft carrying the Rebecca unit. The difference in signal amplitude between the two aerials gave the bearing of the Eureka beacon, while the delay between transmission and reception of the return pulses gave range. The system was effective only to within two miles, when the blip viewed aboard the aircraft merged with the signal transmitted by the interrogator, distorting the range, at which time the crew had to switch to visual means of locating the drop zone. One ground unit to tell me the exact location and one in the A/C to detect the position. Pilot could hang on the Eureka beacon. Like for instance used in the Lysander, Halifax or so. It was used for accurate location. You also could be on a bombing g target. The base at Tempsford was close to Henlow. This is less than 15 km from Henlow. Henlow did maintenance, repairs, and assembling of Aircraft. These airfields had not been damaged by the Germans. Henlow was only hit once with only slight damage and low casualties. ECM equipment (Electronic counter measures) Equipment for jamming is shown. Many Lancaster were fitted with jamming equipment. To jam the German Würzburg radar, the system was called Carpet (see photo). The system was a frequency receiver, which marked the frequency used by the Würzburg radar so that on future missions on this frequency jamming could be done. Even more automatic system was used during the war. Beside this is the window strip (Düppel) shown. Larger Aircraft had VHF too with whip antenna and wire antenna for MF as navigational aid also. The navigational beacon they used frequencies of 300 - 400 KHZ, which is MF. The radio operator did some of navigation during the further years of war. The equipment became more sophisticated. For detecting an aircraft approaching from the back the rear antenna was fitted. Rear antenna, equipment: If switched on, a good identification for night fighter. IFF IFF receiver at is actually a transponder. Gets ground signals and transmits back information. The information could be location call sign or so. It was secret enough not to let Germans to find out. Therefore there was a detonator to destroy the system before it was found by the enemy. IFF system was used from quite early on, but it was very basic. It was not very good. The fighter A/C was fitted with a second channel. This equipment transmitted 14 seconds every minute unmodulated no information on the carrier. American short wave receiver replaced the R1155 was used by both the USAF and the RAF. The other unit is a transmitter tuning box. Lots of USAF equipment was used later in the war used by the RAF as well. Knickebein The blind landing was developed before the WWII and it was developed further on as war started. The German used Knickebeinbeam for blind landing and even for blind bombing. The VHF station at the south coast could read the Knickebeinbeam, and in Britain they also could read the single beam where the A/C was to fly on it. If they knew the target, the jamming was switched on. It was also found out how far the A/C was from base and even the distance from target. The single beam was than transmitted from TV station in London (Alexander Palace) to disrupt the German beam by causing a phase difference in the beam transmitted from the German base in France and the beam actually received by the aircraft. This was enough to make the distance from the target from the base. Actually with this method British signals gave the German Bomber crew the signal to release the bomb. Just the target was selected by the British. Y-Station This Y-Station (as shown in the museum) system was used to listen to German Information. What German Enigma was sending was picked up and this information was than send back to Bletchley Park. The British listened regularly to the German traffic. The British used the Typex code and as it is known today, the Germans never could read the British traffic.