From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Flight tests of a steam-cooled Hart aircraft, focusing on modifications to the cooling system to prevent freezing.
| Identifier | ExFiles\Box 179b\3\ img072 | |
| Date | 30th January 1933 | |
| R.A.E. COPY OF REPORT RECEIVED FROM HAWKER AIRCRAFT LTD. DATED KL.1.A2. The steam cooled Hart is again in Service and did a climb to 15,000 ft. yesterday (see graph.) Since the last series of flights several months ago the system has been somewhat altered. (See sketch.) A Hotwell cooler has been built onto the bottom of the condenser. It consists of a number of tubes similar to those used in the condenser. A water bleed is taken from the header tank into the bottom of the cooler so that the hotwell pump has always got some water to pump. The bleed allows one pint to flow per minute. The idea of being led into the bottom of the cooler is to prevent freezing during glides. The hotwell is insulated from the cold by an asbestos jacket, and the pipe from the hotwell to the hotwell pump is also lagged. From the first flight it appears that the Hotwell gets very cold if not actually freezing. The hotwell temperatures were not taken but the 'inlet to hotwell pump' temperature dropped to 17°C, having glided from 15,000 ft. to 8,000ft., and the 'hotwell suction gauge' went up from ½ lbs. to -3+ lbs. depression denoting a restriction, which rather points to freezing of the hotwell. A repeat flight will be carried out, and if the hotwell does freeze the water bleed from the header tank will be increased in order to keep it warm. The cooler keeps the hotwell temperature down to about 75°C. on the climb which gives the pump a chance to function efficiently. The oil temperatures were rather high reaching the same figure ( i.e. 70°C. on the climb to 15,000ft.) at a day temperature of +3°C. as was obtained in the Summer (day temperature being + 16°C.) The starting temperature in both cases being 35°C, a 7 element cooler was used in both cases. | ||