| Condition: |
| Engine Jumo 213 A/1021521415 to 8.9 |
| Engine Jumo 213 A/1021520539 to 28.9 |
| Engine Jumo 213 C/1001580035 |
| D-9 series condition, normal surface without special treatment. |
| Armament: 2 MG 131, 2 MG 151. |
| Propeller: 41276.16 V. |
| Operable landing gear doors.1 |
| Long range fuselage tank. |
| Radiator flap in front of the air intake fixed in flush position. |
| Lenghtened air intake 20.9 to 28.9. |
| Radiator flap control governor attached to propeller pressure circuit. Rücköl vom VDM – Regler fliesst zum (Sauganschluss) des Luftschraubenreglers zurück. |
| Results: |
| 1. | The test flights determined the airspeed indicator error for an Eltron and a Bruhn pitot tube with equal dimensions.
In contrast to the Bruhn pitot tube, the compressibility error of the Eltron tube, as deliverd with 3 d slot distance, is considered very large, particularly with level speeds. |
| A Bruhn tube is consequently more appropriate for test flights. |
| 2. | The airplane was measured for speed using combat and take-off power.
The following speeds were obtained without ETC and with main (operable) wheel doors: 398 mph (641 km/h) at combat power with a full throttle height of 19,357 feet (5900 m) and 413 mph (665 km/h) at take-off power with a full throttle height of 20,177 feet (6150 m).
The radiator flaps were set on flush postion (Strakstellung) during these flights. |
| Only a small reduction in full throttle height (~100 m) occurs by completely opening all radiator flaps up to the non-powered flap, in front of the air intake in flush position setting,
while the level speed is reduced by approximately 32 mph (50 km/h). |
| Speeds increase 9 to 10 mph (15 to 16 km/h) below and 17 to 18 mph (28 to 29 km/h) above full throttle height, with the change from combat to take-off power. |
| The first engine failed from supercharger damage after a short period of operation. The lattice filter built into the air intake broke and parts of it dropped into the supercharger. |
| The second engine also suffered supercharger damage. The cause here is unknown. The C-engine, Serial Nr. 1001580035, from the failed V-53 and measured on the Jumo altitude test bed, was inserted as a
replacement. |
| 3. | Climb FTH (Abfallhöhe)3 could be increased over ~ 700 m with this machine by a fixed setting of the non-powered radiator flap in front of the air intake.
Like the further trials, e.g. Durchsteigen of the full throttle height with completely closed flaps (bezw.), extension of the air intake up to the point of the radiator flap swivel axis position (according to photo NR. 20027)
showed a further improvement is not possible and the above-mentioned change is sufficient for performance improvement. |
| Details of these trials are to be taken from a special report |
| 4. | Except for the first inexplicable difference of 5° in the lubricant temperature gradients, no change of the engine temperatures was found in combat power climb due to air intake flap setting. |
| For the condition "all radiator flaps up", the following values resulted at the height where temperatures peaked (Temperaturumkehrhöhe): |
| Coolant temp. Radiator entrance tKE = 104° (teina + 26°) |
| Lubricant temp. Engine entrance töME = 129° (teina + 21°) |
| In comparison, the values for the condition before air intake flap setting: |
| tKE = 104° (teina + 26°) |
| töME = 124° (teina + 21°) |
| These temperatures so far are large relative to 213 A. |
| 5. | On suggestion of the company Jumo, the back oil attached at the propeller pressure circuit of the radiator flap automatic controller was supplied like that to the suction connection propeller pressure circuit.
No objections showed up in the propeller and radiator flap control during the last flights, which were led through this condition of the installation.
One check is still pending, whether the flaps also remain in their end positions in the dive. (no mesh filter before VDM automatic controllers anschl.) |
