Junkers Jumo 207
The Jumo 207 was an opposed piston engine and was a further development of the Jumo 205 in order to obtain a usable altitude engine.
history
The Junkers company had already made great efforts in the field of soaring. With the Ju 49 and the Junkers L88 engine equipped with a high- altitude loader, a height of 13,000 meters had already been reached. The exhaust gas turbocharger (ATL) was the better charging method, as it did not divert any power from the engine, the diesel engine with its lower exhaust gas temperatures and higher compression was ideally suited for this. That is why it was planned as early as 1932 during the development of the Jumo 205 to use it with an ATL as an altitude motor. By 1936, Junkers engineers had already reached full pressure heights of 10,000 meters. The greatest problems caused the ATL as a new technology and its integration into the engine system, since the opposed piston engine was equipped with a scavenging fan. In addition, the Reich Aviation Ministry (RLM) saw no need for such an engine, neither for civil nor for military aviation, so the project was stopped. With the outbreak of the Second World War, however, the RLM commissioned the Junkers company with a "special order" for an altitude motor.
The Jumo 207A was brought to series production. He owned the engine block of the Jumo 205 and was equipped with an ATL and charge air cooling. The engine developed 880 hp at a full pressure altitude of 10,000 meters at a speed of 2800 rpm. In the Ju 86 P, two of these engines ensured safe reconnaissance flights over 12,000 meters. However, with the further development of aircraft engines in the course of the war, this height was soon no longer sufficient. The further developed version Jumo 207B reached the full pressure height of 10,500 meters. This was achieved by throttling the ATL at ground level. The engine thus developed 800 HP on the ground, at an altitude of 10,000 meters it delivered 750 HP, at 14,000 meters it still produced 500 HP. Without the ATL it would only be 150 hp at an altitude of 14,000 meters, but it would not have been able to reach this altitude. The aerodynamically improved Ju 86R could safely perform flights with the Jumo 207B up to an altitude of 15,000 meters. The Jumo 207C was created for those flying boats that need their greatest power at take-off. Here, the ATL was used unthrottled and an output of 1,100 hp at a speed of 3,000 rpm at sea level was achieved. The large flying boat Blohm & Voss BV 222 , however, required an even higher performance. For this reason, the bore for the Jumo 207D was enlarged to 110 mm, resulting in a displacement of 18,250 cm³ and it developed 1200 hp at a speed of 3000 rpm. In 1944 it was ready for action, but the war events meant it was no longer needed. The Jumo 207 was an engine with a very special field of application, which is why it was only built in a small series. In total, no more than 200 to 300 engines could have been manufactured.
Technical specifications
| Parameter | Data |
|---|---|
| Manufacturer | Junkers engine works |
| Construction year | 1939 |
| design type | 6-cylinder opposed piston engine , two-stroke, diesel |
| Displacement (bore × stroke) | 16.62l (105 mm × 160 mm 2 ×) |
| Charging | Rinsing fan with ATL |
| Dry matter | 805 kg |
| Starting power kW (PS) | 650 (880) |
| rotational speed | 2800 rpm |
| Full pressure height | 10,000 m |
| spec. Fuel consumption g / kWh (g / PSh) | 231 (170) |
variants
- Jumo 207A - altitude engine with ATL, flushing fan, intercooler, 10 km full pressure altitude, small series
- Jumo 207B - improved altitude engine, 10.5 km full pressure altitude, small series
- Jumo 207C - overloaded floor motor, ATL, flushing fan, 5 km full pressure altitude, small series for BV 222
- Jumo 207D - overloaded floor engine, enlarged to 18.2 l displacement, otherwise like 207C, only test bench
swell
- Kyrill von Gersdorff, Kurt Grasmann: aircraft engines and jet engines. Bernard & Graefe Verlag, Bonn 1981, ISBN 3-7637-5272-2 .
- Reinhard Muller; Junkers aircraft engines. AVIATIC Verlag, 2006, ISBN 3-925505-79-2 .
