Between 1935 and 1940, several He 70s were used for testing new equipment by the Kommando der Erprobungsstellen situated at the Erprobungsstelle Rechlin near Lake Müritz, east of Berlin, and at other evaluation sites too. Unarmed He 70s were used for personnel transport or liaison duties until the early forties.
The He 177 V29 (GO+IF, production number 15155), an aircraft belonging to the A-1 series, was mainly used for defensive armament trials at the E-Stelle Rechlin. Note a small remote-controlled weapons turret could be installed in the lower front section of the aircraft.
An aviator test- and training institute had been established at Rechlin on Lake Müritz in 1916. On 29 August 1918 the Flieger Versuchs- und Lehranstalt (Aircraft Trial and Test Station) Rechlin was established under the designation Kommandant der Flughäfen (Officer Commanding, Aifields) Müritzsee under the command of Hauptmann (Captain) August Joly. Up until 11 November 1918 (the end of the First World War), this new evaluation unit tested all new aircraft and equipment.
New but secret flight testing activities were recommenced in 1922. Early in 1928 the existing buildings at Rechlin were taken over by the Albatros Flugzeugwerke (aircraft factory) GmbH. Additionally a few more hangars were constructed and used by Albatros. From 1928 onward, all facilities at Rechlin were steadily and regularly enlarged to fulfil the many new tasks required of this secret evaluation site; several more hangars were built from 1929, for example. With the exception of the BFWM22, nearly all new German aircraft developments were sent to Rechlin for evaluation. Despite many evaluation flight crashes, it succeeded in selecting those aircraft, from the many designs which could have fulfilled the demands of the Truppenamt, used to arm what was to become the future Luftwaffe. On 1 June 1931, the Erprobungsstelle of the Reichsverband der Deutschen Luftfahrtindustrie (Reich Society of Aircraft Manufacturers), or RDL, situated at Staaken and Rechlin, was split into five separate departments, of which the major two were those used for the testing of new aircraft and new aircraft engines. The others evaluated new wireless systems, other ancillary equipment and were involved in problem solving in other aviation matters, such as aerial photography The RDL was ordered by the Truppenamt (Army Office) of the Reichswehr to continue with its secret development of German military aircraft as ordered in the autumn of 1929. In 1932, several transport aircraft were tested to examine if they would be capable of use as auxiliary bombardment aircraft. Besides the Ju G24 and Ju 52, the Dornier Merkur (Mercury) and Rohrbach Ro VIII were evaluated as part of this program. Additionally, the first batch of fighters including the He 51 and Arado Ar 65 was tested here.
On 30 January 1933, important proposals were put forward concerning an enlarged facility at Rechlin for the development and testing of new aircraft. On the back of this, a new military airfield at Lärz (near Rechlin) and subsequently the E-Hafen at Roggentin nearby were established by the new Luftwaffe command, both to accommodate the testing of aircraft and ancillary equipment.
By 1936, a huge Luftwaffe evaluation site had evolved, incorporating several engine testing sites. Buildings for officers and specialists were built around the main airfield near Ellerholz, east of Rechlin. In addition, a row of huge hangars was erected together with a widespread refuelling system and an ammunition dump, just east of the small village of Rechlin proper on the shore of Lake Müritz. Also engine test beds, a power station and the control tower were all built, followed by a second tower a short time later, again constructed near Lake Müritz. Subsequently, near the evaluation site itself, several smaller houses, called Siedlung Rechlin, were built to house officers and engineers working at the Rechlin evaluation centre in order that they should not live too far from their work!
On 9 November 1934, a secret exhibition was staged at Rechlin presenting the He 45, He 46, He 70, Ju W34, Ju 52 and Do 11. which were all shown with ancillary equipment fitted.
Then in 1935, a new German Luftwaffe was officially established. During the course of that year and the following year, many brand new combat- and training aircraft, especially the first Bf 109, Do 17, Hamburger Flugzeugbau Ha 137, Henschel Hs 123, Hs 126, He 111, Ju 86 and Ju 87, were sent to Rechlin to undergo their first Luftwaffe evaluation.
On 22 May 1936, an impressive exhibition was held at Rechlin showing not only the Ju 86, the He 111 and the Do 17 bombers, but also the He 112 and Fw 159 fighters together with many more improved types. Beside the Reichsminister der Luftfahrt (Reich Minister of Air Transport) and Oberbefehlshaber (Supreme Commander) of the Luftwaffe, Hermann Goring, the Reichskriegsminister (Reich War Minister) von Blomberg together with several other high-ranking officers were present. A few weeks later, on 10 July 1935, the same aircraft were inspected by Adolf Hitler himself.
In 1937, still more new prototypes went to Rechlin; beside the Messerschmitt Bf 110 destroyer, engineers at Rechlin commenced their evaluation of one of the new Ju 88. Furthermore, the Fw 57 and a few Henschel aircraft, notably the Hs 122, Hs 124 and Hs 127, were intensively tested there. During the course of 1937, six new aircraft crashed at or near the site, killing 18 members of the Rechlin evaluation team. However, despite all the dangers associated with the evaluation of new aircraft types, it was viewed as simply too important a task to stop the program at this stage.
In 1938, increasing numbers of improved variants of the combat aircraft expected to enter Luftwaffe service arrived at Rechlin. Most of them were prototypes of the Bf 109 and He 111, but there were also some new designs such as the Ha 141, later designated the Blohm & Voss BV 131, the Ar 198 and even a few more experimental types found their way to Rechlin at about this time. Additionally, the first Do 217, more than just an improved Do 17, became ready for testing as the third two-engined bomber earmarked for service with the Luftwaffe. Simultaneously, the Ju88 was tested as a heavy dive-bomber armed with special weapon loads.
In 1939, all aircraft evaluation was placed under the command of the Generalluftzeugmeister (Officer In Charge, Aircraft Procurement) who was responsible for the Technisches Amt (Technical Office) of the RLM, and who was also responsible for all other evaluation sites. Despite new responsi-bilites given to the various departments within Rechlin, flight tests were still carried out in the usual way. Another important aircraft reached Rechlin that year: the first Focke-Wulf Fw 190. In addition, the Fl 265, the Hs 128 V1 and the Me 210 V1 were all tested by pilots at Rechlin.
During 1940, beside the Fw 190 and Me 210, a new four-engined bomber, the He 177 V1, arrived at Rechlin, to be tested intensively by the evaluation team. Many technical problems were found during the evaluation of these types, though not all of the issues could be resolved by the Rechlin staff due to shortened development time constraints of the Me 210 and the He 177 in particular. At about the same time Rechlin succeeded in testing Fw 190s fitted with the first of the BMW 801 radial engines which would be used to replace the less powerful BMW 139s in the then not-too-distant future. To improve existing fighter power, variants with larger aircraft engines were sent to Rechlin; several new Bf 110s were evaluated in 1940, together with the first prototypes of the new Bf 109F and the first pre-series Do 217.
As of 1941, evaluation tasks were expanded once more; the development of the large He 177 bomber involved much work in order to obtain a reliable aircraft finally capable of front line service.
After the outbreak of hostilities, theatres of war became increasingly large, close air support becoming increasingly important for the Wehrmacht ground units fighting on long fronts, often without powerful enough weapons and enough supplies. Therefore it became an important task for the Erprobungsstellen to test the first Hs 129s, as well as special ground attack variants of the Fw 189 and the early Fw 190 fighter/bomber.
At this stage of the war it became obvious that German air transport capacity was too limited to fulfil all its necessary tasks over the European war theatre and the north African desert. Therefore, new huge gliders were constructed which underwent test and evaluation activities in 1940. Beside the Gotha Go 242, far larger types such as the Ju 322 and the Me 321 Gigant (Giant) were evaluated, although only the Go 242 and a motorised variant of the Me 321, the Me 323, actually passed evaluation at the time.
Month by month, new variants of all the more common combat aircraft were transferred to Rechlin for evaluation. In 1941 and 1942, Rechlin pilots not only flew the newest Bf 109s of the early G-series, but also the improved Bf 110 aircraft of both the F- and G-series and yet more Fw 190 variants. Simultaneously, more powerful bombers were brought to Rechlin. Most of these were prototypes of the Do 217-K and –M, being powered by BMW 80IDs and DB 603As respectively At the time there were insufficient resources for the Reich to produce four-engined strategic bombers, such as the Allies’ Fortress or Lancaster. Therefore those types already in service, such as the He 111 and Ju 88, were continuously improved to allow missions under more difficult conditions during the defence of the Reich, for example under heavier AA fire and against the increasingly potent fighters of the Allies. By the middle of the war, the Luftwaffe was demanding the introduction of heavier destroyer aircraft types to defend Reich territory both by day and by night. Prototypes of these well armed aircraft, such as the Do 217N and Ju 88C, were sent to Rechlin for testing and evaluation. Later in 1942, the first Ar 240 and He 219 Uhu (Owl) prototypes were available and, as usual, were first tested by their manufacturers before being handed over to the various E-Stellen. Also, various new transport aircraft became available for testing at this time. Besides the Go 244, a motorised glider, the Ju 252 and Fi 256, both German liaison and transport types, were to start their evaluation phase. However, only a limited number of each were produced due to the lack of sufficiently high quality raw materials.
Rechlin’s role was however not limited to German aircraft, several captured aircraft being sent to the site for evaluation. All over German-held territory, teams of specialist engineers were responsible for the recovery of any allied aircraft shot down or forced to land. Those allied machines suffering only limited damage were of tremendous interest to these men, who were also responsible for the recovery of undamaged spare parts from similar aircraft, thus allowing the Rechlin specialists to repair damaged enemy aircraft for comparative flights with German types.
From 1942 onwards, numerous photoreconnaissance aircraft of the RAF attempted to probe the secrets of the Rechlin test centre. All unrecognised aircraft or those unknown to the reconnaissance specialists back in the UK were labelled “Rechlin #”. For example, “Rechlin 104” photographed on 28 June 1943, was possibly the first Ar 232 to land at the airfield. Photos of various heavy night fighter prototypes and new Do 217 variants then being tested at Rechlin were also brought back to England at around this time.
The war visited the E-Stelle Rechlin itself early in 1944, when Allied P38s hit hard at Rechlin-Lärz and destroyed a few of the prototypes dispersed around the second evaluation airstrip at the base. On 24 May 1944, a total of 13 four-engined bombers of the 388th Bomber Group appeared over Rechlin-Lärz and dropped 31 tons of bombs although they failed to hit even one of the prototypes located there.
Despite these attacks, the pilots, engineers and men continued with their work to create new weapons for the Luftwaffe. Between May and August 1944, reconnaissance aircraft of the RAF located the first Ar 234 and Ju 287 types, together with a few Me 262s based there. Overwhelming allied air power had not been significantly hindered from reaching their targets all over Europe by the then available German piston-engined fighters or destroyers. Therefore German aircraft manufacturers were ordered, within the shortest period of time, to construct well armed jet fighters and bombers to prosecute a new kind of defensive and offensive air war against the Allies. Not only was the Me 163, a small rocket-powered point-defence fighter, constructed and tested at this time, but also several prototypes of the Me 262 and a few He 280s were evaluated, both in Bavaria and at other sites all over the Reich.
On 12 and 13 June 1944, the E-Stelle Rechlin presented a complete review of all the various prototypes then being tested. Beside the huge He 177 (the B-5-prototype), the fast Ju 88S-3, the He 219 and the new Focke-Wulf Ta 154 Moskito were shown. Furthermore, all the new major fighter variants and conversions were flown or shown at the event. Beside the Ar 234, Me 163, the new Do 335 and the Me 262, there were also examples of the latest captured Fortress, Liberator, Lightning, Mosquito and other Allied types shown.
On 25 August 1944, Rechlin was again hit, this time by 179 bombers of the US 8th Air Force. There was damage to the base this time but it still managed to function, although unlike the previous raid a few prototypes were lost or damaged. Late in 1944, the evaluation of German jet aircraft projects was continued with great vigour. Specialist teams worked on the He 111H which was needed for airborne release trials of the V1. Additionally, desperate attempts were undertaken to use manned Vis, code-named Reichenberg, to destroy more important targets through the use of suicide attacks, but on 15 March 1945 all work on this particular weapon was ceased.
Meanwhile, in January 1945, the Red Army had advanced faster than estimated after the Heeresgruppe Mitte (Army Group Centre) had been severely mauled and had practically broken down. To stem the Russian ground forces’ advance, all available aircraft were required, including those at Rechlin. The inventory of E-Stelle Rechlin at the time consisted of both series aircraft and prototypes which was immediately organised into two night bomber Staffeln flying the He 111, Ju 88 and Ju 188. Also a fast Bomberstaffel (bomber squadron) consisting of nine Ar 234s, two ground attack formations flying the available Fw 190s and two fighter units with a total of 13 Bf 109s and Me 262s were all established. The complete Gefechtsverband (Fighting Unit) KdE was dissolved, however, on 19 February 1945, due to serious problems in using prototypes for offensive missions. Also, with Russian ground forces still advancing rapidly, the evacuation of E-Stelle Rechlin to Lechfeld in Bavaria began on 24 March 1945.
Once re-established there, the evaluation of the Ar 234, Me 262 and the new He 162 Volksjäger (Peoples’ Fighter) could start again. Only very few prototypes had been flown from Rechlin to Lechfeld, but that included the first pre-series Ar 234C-3 and some of the He 162s. Meanwhile Rechlin and Lärz were severely hit by American Liberators on 10 April 1945. The last prototypes left Rechlin on 20 April 1945, destined for Bavaria and Northern Germany, the last members of staff of the E-Stelle leaving by train on 29 April 1945 before the facilities were blown up by German forces the following day.
Besides the E-Stelle Rechlin, several similar units were established across Germany, though they were used for other purposes.