Many other parts of Thuringia were involved in the German rocket program. Even before the A4 production had started in he Mittelwerk the decision was taken to build new engine test stands close to the production facility. Such a facility here made the final assembly much easier, because the power-plants did not have to be transported all the way to Peenemünde for test-firing. Roughly 10% of the engines were tested.

Gerhard Degenkolb, Martin Schilling and Bernhard Tessmann had located a slate-quarry near Lehesten were such a test faciliy could be erected. The slate-quarry was ideally suited for straight-down-the-wall combustion chamber testing without the need for flame detectors.

The Oertelsbruch slate-quarry near the hamlet of Schmiedebach located near Lehesten just to the south of he city of Saalfeld was the chosen location of the new test facility. Here the so-called Vorwerk-Mitte was to be erected. The "Steinbruch Verwertungs GmbH" leased the quarry for 170,000 Reichsmark. The head-office of the company was in Atnang-Puchheim. Besides Dr. Rickhey SS-Sturmbannfuehrer Dr. Fritz Loth was in charge of the construction and the managing of the project. The SS-Sonderinspektion II under SS-Hauptsturmfuehrer Gessen supported the project and organized the material and manpower. Besides the test stands, an underground liquid oxygen plant was to be constructed. It was a sound decision to also construct a production plant for liquid oxygen close to the rocket motor test stands. The transport of the liquid oxygen over larger distances would be eliminated.

The Oertelsbruch facility mined slate from the side of the mountain for quite some time. Tunnels were driven into the mountain to mine the slate. The Wifo had shown an interest in the facility to use the facility for the storage of important raw materials. According to Wifo documents, the slate quarry belonged to the "Kuehler Morgen GmbH" in Roettesdorf. Construction begun on September 21, 1943. Manpower came from the concentration-camp Buchenwald. The camp received the name "Laura". In six month the facility was completed and it received he code-name "Rotbutt".

When the project was started seven kilometers of tunnels and 54 halls already existed. Some of these halls 400 square meters in size were enlarged to 600 square meters. The facility was an open pit operation 190 feet deep with 2 tunnels running into the mountain. The two tunnels were roughly two meters wide and two meters high. At the point where the slate was mined, the tunnels reached a height of 15 meters. Seeping water was not a problem and the rock above the tunnels was very strong. Nearby, quarters for 100 workers were available. The facility had 20.000 sqm of space available.

In the slate quarry the test stands were erected. The quarry sides, 40 m high, were to be used to hold the concrete chambers for the test stands. They were 3.6 m long, 3 m wide, and 4.2 m high with concrete walls 0.4 m thick. The back was open. A steel frame on which the rocket motors were mounted was located in the front. A large opening in the floor allowed the rocket exhaust gases to escape. Both chambers were 25 meters apart.

In the test rooms, the thrust, fuel pressure and all other measuring instruments were installed. For this purpose, copper pipes were installed leading from the combustion chamber to the measuring instruments in the tunnel. The two rooms holding the measuring instrument were under construction when the war ended. Some of the instruments were already installed.

The A4 rocket engines were vertically installed in a movable steel frame. This arrangement allowed for the quick movement of the motors. One of the tunnels in the quarry was equipped with 2 tanks holding alcohol and liquid oxygen. The tunnels, which were approximately 100 m long, were connected to different side tunnels. Train tracks reached into he facility.

The huge underground tunnels and caves were just ideal for the secure production of liquid oxygen. Lehesten produced 8 tons of liquid oxygen an hour. Production run for 24 hours a day, 27 straight days without stopping every month. The remaining days of each month the production was shut down to unfreeze the equipment. Lehesten produced 5,000 tons of liquid oxygen a month. The facility was handed over to the Americans by the SS commander of the facility. After the Americans pulled out the Russians took over.

On July 15, Aleksey Isaev and Arvid Pallo were dispatched to Lehesten, the site of the A-4 engine firing stand, one of the few rocket-related facilities, the Soviets found virtually untouched, after the departure of the Americans. The same month, the top Soviet specialist in rocket engines, Valentin Glushko was sent to Germany with a group of his associates from OKB-SD, a design bureau specialized on propulsion systems for rocket-assisted takeoff for military aircraft. Lehesten became a home for Glushko's team, where test firings resumed as soon as September 6, 1945. Dr. Joachim Umpfenbach initially directed the firings, however the same month, V. L. Shabransky, one of the specialists from OKB-SD, was appointed the director of the test site, the position he held until Soviet work on rocketry concluded in Germany in January 1947.

In August the Zentralwerke's V-2 engine static test stands were back in operation. By December 1945 600 German and Soviet specialists were at work at Zentralwerk. In March 1946 the first two complete V-2's were ready for test. At the engine test stands German and Russian specialists improved the standard V-2 engine for better thrust and performance. A series of 40 test firings between July and September 1946 used modified propellant mixer heads and varying mixture ratios. Thrust of the basic V-2 engine had been increased from 25 tonnes to 30 tonnes.

When the Russians left, the entrances were blown in. It was not until November 20th 1952 that anything happened at the facility. It was at  that time that a GDR company was asked to clean the mine. In a latter back to the ministry in 1953 the company wrote hat at least 88 tonnes of steel scrap was still in the mine and that it would take a lot of money to clear everything out. Nothing was done and it seems that the scrap is still there.

See also www.slatecity.de