Post by Dave Homewood on Jul 14, 2011 2:34:03 GMT 12
An interesing thing I have stumbled onto. Whilst searching to see if there was any wartime newspaper reference to jet aeroplanes on PapersPast (out of curiosity, to see if they were kept secret or announced to the world) I found this article. It's first paragraphs stunned me. They had jet boats in the 1890's? Everything I have ever heard and read about jet boats is they were invented by Sir William Hamilton of NZ in 1954. Yet this article from ten years previous to his invention it states 50 years previous again there had been jet powered boats on canals and as lifeboats.
Evening Post, Volume CXXXVII, Issue 5, 8 January 1944, Page 4
NOTES ON THE WAR
JET AEROPLANE
ALLIES' NEW MACHINE The most interesting piece of news today is the reported success of an Allied jet aeroplane, after years of experiment, promising a new developmerit in war aviation, and, possibly, in civil air transport later. Jet propulsion of aircraft is not a new idea, and for the propulsion, of small craft at sea, notably life-boats, it was tried fairly successfully at least fifty years ago. In each case the general principle is the same —taking in water or air, as the case may be, at the bows, and expelling it at the stern,- power being applied through pumps.
For inland waters, such as canals, rivers, or lakes, forms of jet propulsion are still used for shallowdraught craft, the main advantage being that there is no screw propeller or paddle wheel to foul the bottom or water weeds, and that less damage is done to the banks by this method of propulsion than by the wash of screw propellers.
But it cannot be said that jet propulsion for water craft, measured in speed for power used, is comparable with the screw propeller. Some Difficulties. With aircraft the same objection has been raised so far to all experimental jet-propelled craft. They are not efficient.
The Caproni-Campini Italian jet-propelled aircraft could only do about 130 miles an hour in its trip from Lombardy to Rome, and even then it had to call at Pisa to refuel. Wastefulness in fuel and lack of speed proved a fatal obstacle to adoption at the stage then reached by the Italians.
Undisclosed Secret.
What precise new form Group Captain Frank Whittle's successful development has taken to make it worth while for the British and American authorities to adopt it for mass production is not conveyed in the news or comment cabled. The secret must lie in the design and devices employed to secure at least a reasonable economy of fuel for the results achieved, compared with the orthodox internal combustion engine and airscrew. This latter combination is fairly efficient in relation to the theoretical possibilities of power in the petrol.
The most modern aero-engines will, with the fuels now available, convert into power at the crankshaft over 30 per cent, of the power available theoretically in the fuel. The best airscrews attain a propulsive efficiency of 80 per cent. Thus nearly a quarter of the power represented by the fuel is turned into useful work for the propulsion of the aircraft.
The disadvantages lie mainly in the complications resulting from attempts to get more power by increasing the number of engines and airscrews and the number of cylinders to each engine. There are also other problems caused by limitations to the,diameter of airscrews and the air resistance of engine nacelles.
The speed of airscrew blade tips must be kept within a certain figure, about 900 feet a second, because if the tips attain the speed of sound in air (about 1080 feet a second) there is a serious loss of efficiency. In jet propulsion air is drawn in at the front of the aircraft (either in the nose or through ducts in the forward edge of the wings) and expelled at the rear (either through the tail end of the fuselage or the trailing edge of wings). The air is compressed in its course and fuel is introduced and fired at the correct point and the products of combustion, with the volume of heated compressed air, pass out to the rear of the machine, giving the necessary "push" or thrust to the aeroplane.
Compression Problem
The mere idea is thus fairly simple, but practical development must have been full of difficulties. First of all, there is the problem of compression. To deal with the necessary volume of air it would seem that turbo-compression must be used, like a steam turbine in reverse, or like the multistage high-lift turbo-water pumps. Such air compressors have hitherto been of low efficiency compared with cylinder-and-piston air pumps, and in the case of gas or internal-combustion turbines, constructed at odd times over nearly " fifty years, overall efficiency has been very poor, far below that of the gas engine, the petrol motor, or the Diesel engine.
Thus the power available for propulsion, as in the Campini jet propelled aircraft, has hitherto been small for the consumption of fuel. Group Captain Whittle's efforts over ten years must have got over all these difficulties; otherwise the Allied authorities would never, in the rush of war production, have fostered the development of the invention to the successful stage. How the inventor has accomplished his profoundly difficult job has not yet been vouchsafed to the world, but engineers are well aware of progress made with hot gases travelling at high speed, as in the Velox boiler, to be seen in the Evans Bay power-house, and also in various forms of exhaust turbines developed, like the Velox, largely in Switzerland. Further information will be awaited with great interest. "
So, who did invent the jet boat? It obviously was not Bill Hamilton, although he did create the Hamilton Jetboat of course.
Evening Post, Volume CXXXVII, Issue 5, 8 January 1944, Page 4
NOTES ON THE WAR
JET AEROPLANE
ALLIES' NEW MACHINE The most interesting piece of news today is the reported success of an Allied jet aeroplane, after years of experiment, promising a new developmerit in war aviation, and, possibly, in civil air transport later. Jet propulsion of aircraft is not a new idea, and for the propulsion, of small craft at sea, notably life-boats, it was tried fairly successfully at least fifty years ago. In each case the general principle is the same —taking in water or air, as the case may be, at the bows, and expelling it at the stern,- power being applied through pumps.
For inland waters, such as canals, rivers, or lakes, forms of jet propulsion are still used for shallowdraught craft, the main advantage being that there is no screw propeller or paddle wheel to foul the bottom or water weeds, and that less damage is done to the banks by this method of propulsion than by the wash of screw propellers.
But it cannot be said that jet propulsion for water craft, measured in speed for power used, is comparable with the screw propeller. Some Difficulties. With aircraft the same objection has been raised so far to all experimental jet-propelled craft. They are not efficient.
The Caproni-Campini Italian jet-propelled aircraft could only do about 130 miles an hour in its trip from Lombardy to Rome, and even then it had to call at Pisa to refuel. Wastefulness in fuel and lack of speed proved a fatal obstacle to adoption at the stage then reached by the Italians.
Undisclosed Secret.
What precise new form Group Captain Frank Whittle's successful development has taken to make it worth while for the British and American authorities to adopt it for mass production is not conveyed in the news or comment cabled. The secret must lie in the design and devices employed to secure at least a reasonable economy of fuel for the results achieved, compared with the orthodox internal combustion engine and airscrew. This latter combination is fairly efficient in relation to the theoretical possibilities of power in the petrol.
The most modern aero-engines will, with the fuels now available, convert into power at the crankshaft over 30 per cent, of the power available theoretically in the fuel. The best airscrews attain a propulsive efficiency of 80 per cent. Thus nearly a quarter of the power represented by the fuel is turned into useful work for the propulsion of the aircraft.
The disadvantages lie mainly in the complications resulting from attempts to get more power by increasing the number of engines and airscrews and the number of cylinders to each engine. There are also other problems caused by limitations to the,diameter of airscrews and the air resistance of engine nacelles.
The speed of airscrew blade tips must be kept within a certain figure, about 900 feet a second, because if the tips attain the speed of sound in air (about 1080 feet a second) there is a serious loss of efficiency. In jet propulsion air is drawn in at the front of the aircraft (either in the nose or through ducts in the forward edge of the wings) and expelled at the rear (either through the tail end of the fuselage or the trailing edge of wings). The air is compressed in its course and fuel is introduced and fired at the correct point and the products of combustion, with the volume of heated compressed air, pass out to the rear of the machine, giving the necessary "push" or thrust to the aeroplane.
Compression Problem
The mere idea is thus fairly simple, but practical development must have been full of difficulties. First of all, there is the problem of compression. To deal with the necessary volume of air it would seem that turbo-compression must be used, like a steam turbine in reverse, or like the multistage high-lift turbo-water pumps. Such air compressors have hitherto been of low efficiency compared with cylinder-and-piston air pumps, and in the case of gas or internal-combustion turbines, constructed at odd times over nearly " fifty years, overall efficiency has been very poor, far below that of the gas engine, the petrol motor, or the Diesel engine.
Thus the power available for propulsion, as in the Campini jet propelled aircraft, has hitherto been small for the consumption of fuel. Group Captain Whittle's efforts over ten years must have got over all these difficulties; otherwise the Allied authorities would never, in the rush of war production, have fostered the development of the invention to the successful stage. How the inventor has accomplished his profoundly difficult job has not yet been vouchsafed to the world, but engineers are well aware of progress made with hot gases travelling at high speed, as in the Velox boiler, to be seen in the Evans Bay power-house, and also in various forms of exhaust turbines developed, like the Velox, largely in Switzerland. Further information will be awaited with great interest. "
So, who did invent the jet boat? It obviously was not Bill Hamilton, although he did create the Hamilton Jetboat of course.
