28:
152:, the Director of Aeronautical Supplies, made the decision to place large orders for the Dragonfly. He briefed the British War Cabinet in March 1918 on what he considered to be the merits of the design (high power on low weight), and indicated it was the first engine on which 'it might be advisable to standardise', even though it had not been fully tested. With Weir's backing, orders for 11,500 engines were placed from 13 suppliers by June 1918, but in the same month the
184:
caused heat damage and even charring to the propeller. Developed power fell far short of estimates even when the engine was run at 15 per cent over-speed (producing only 315 hp ) and it showed much poorer fuel consumption than expected. Attempts to improve cooling with cylinder redesign were marginally successful, but the death blow fell when it was realized that the engine was designed to run at the torsional
179:
in his book, 'Plane
Speaking' in the chapter headed, 'Cancel the Others...' In this he suggested that Bradshaw had proved to be a better salesman than a designer, and had proved non-committal when asked about initial testing which was ultimately to reveal severe problems with the much-vaunted engine.
183:
Already 30 kg over its designed weight as built, Dragonfly was subject to severe overheating. Gunston referred to it as the worst cooled aero engine ever made. The copper-plated cooling fins proved useless; the cylinder heads tended to glow a dull red at operational speeds, and in extreme cases
136:
air-cooled radial, Bradshaw produced a design for a larger and more powerful engine, the nine-cylinder
Dragonfly. The engine was simple and easy to produce, and was predicted to give 340 hp (254 kW) for a weight of 600 lb (273 kg). One distinctive feature was the use of
156:(RAF)'s Technical Department admitted that complete drawings were unavailable as the design was still not finalised. It was planned that the bulk of the RAF's aircraft would be powered by the Dragonfly in 1919. Types designed to be powered by the big nine cylinder included the
192:, causing severe vibration, a little known condition at the time. These problems proved unsolvable, resulting in an absurdly low service life (around 30 to 35 hours per engine), and the Dragonfly was eventually abandoned.
117:. It was expected to deliver excellent performance for the time and was ordered in very large numbers. It proved, however, to be extremely unreliable and was abandoned when its faults were unable to be corrected.
790:
734:
724:
719:
714:
686:
780:
657:
632:
447:
149:
145:, which were claimed by Bradshaw to be so effective that water would not boil on the surface of the radiators.
785:
679:
277:
169:
262:
672:
481:
232:
36:
199:
had been signed in 1918, as the only other aero engine still in production at that time was the
485:
462:
252:
132:, who was also the company's chief designer. In 1917, after initial promising tests of the
8:
366:
242:
27:
267:
165:
129:
79:
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200:
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237:
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608:
Ewer, Peter. 'William Weir: architect of air power? The First World War chapter',
698:
357:
312:
307:
292:
282:
272:
153:
49:
397:
297:
287:
257:
157:
172:. Of this order 1,147 engines were built, but only nine or ten actually flew.
774:
438:
348:
342:
302:
203:; all other types having been cancelled in favour of the untested Dragonfly.
161:
110:
46:
480:, contemporary American nine-cylinder radial (1921), direct ancestor of the
754:
749:
638:
477:
247:
176:
610:
The
International Journal for the History of Engineering & Technology
407:
142:
114:
221:
360 hp (268 kW), revised pistons and cylinder heads, revised oil system.
744:
695:
391:
375:
189:
125:
69:
599:
Bruce, J.M. "Sopwith Snipe...:...the RAF's First
Fighter. (Part 2). "
196:
185:
759:
739:
709:
664:
195:
Gunston's observations suggested that it had been as well that the
133:
138:
175:
The engine was described in brief by aviation journalist
605:
Volume 6 Number 6, June 1974. Bromley, UK: Fine Scroll.
572:
570:
652:. Marlborough, Wiltshire: Airlife Publishing, 2003.
567:
772:
319:
579:
680:
687:
673:
332:
148:On the basis of the promised performance,
791:Aircraft air-cooled radial piston engines
650:British Piston Engines and their Aircraft
120:
625:Jane's Fighting Aircraft of World War I
328:Jane's Fighting Aircraft of World War I
773:
668:
694:
555:Bruce 1974, p. 292; Ewer 2023, p. 12
400:, 2 inlet and 1 outlet per cylinder
13:
643:World Encyclopedia of Aero Engines
452:0.56 pints per bhp/hour(0.32 L/kW)
14:
802:
645:. London: Guild Publishing, 1986.
113:developed towards the end of the
26:
592:
225:
558:
549:
540:
531:
522:
513:
504:
425:
160:(a derivative of the existing
1:
781:1910s aircraft piston engines
618:10.1080/17581206.2023.2237080
492:
384:
320:Specifications (Dragonfly IA)
602:Air Enthusiast International
458:7 pints per hour (3.97 L/hr)
434:340 hp (254 kW) at 1,650 rpm
7:
471:
206:
10:
807:
488:American aviation radials.
705:
448:Specific fuel consumption
341:nine-cylinder air-cooled
263:de Havilland DH.11 Oxford
34:
25:
20:
627:. London, Studio, 1990.
497:
482:Wright Whirlwind series
467:0.56 hp/lb (0.93 kW/kg)
333:General characteristics
233:Armstrong Whitworth Ara
128:was founded in 1911 by
37:Science Museum (London)
371:1,389.86 in³ (22.78 L)
121:Design and development
463:Power-to-weight ratio
443:0.24 hp/in³ (11 kW/L)
215:1918, 320 hp (239 kW)
35:ABC Dragonfly at the
786:ABC aircraft engines
564:Lumsden 2003, p. 53.
253:Boulton Paul Bourges
510:Lumsden 2003, p.52.
243:Avro 533 Manchester
186:resonance frequency
623:Grey, C.G. (ed.).
576:Gunston 1986, p.8.
268:Nieuport Nighthawk
166:Nieuport Nighthawk
130:Granville Bradshaw
80:Granville Bradshaw
768:
767:
537:Gunston 1986, p.8
528:Bruce 1974, p.292
362:6½ in, (165.1 mm)
201:Rolls-Royce Eagle
103:
102:
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612:, 2023 pp.1-19.
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585:Grey 1990, p.256
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546:Ewer 2023, p. 12
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519:Gunston 1986, p8
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511:
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456:Oil consumption:
353:5½ in (139.7 mm)
238:Austin Greyhound
150:Sir William Weir
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419:Cooling system:
398:overhead valves
387:
380:600 lb (273 kg)
335:
322:
317:
313:Westland Weasel
308:Sopwith Snapper
293:Sopwith Rainbow
283:Sopwith Bulldog
278:Siddeley Siskin
273:Nieuport London
228:
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170:Siddeley Siskin
154:Royal Air Force
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115:First World War
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61:United Kingdom
57:National origin
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109:was a British
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658:1-85310-294-6
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639:Gunston, Bill
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633:1-85170-347-0
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343:radial engine
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303:Sopwith Snark
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111:radial engine
108:
107:ABC Dragonfly
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66:Manufacturer
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699:aero engines
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593:Bibliography
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486:"golden age"
478:Lawrance J-1
461:
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408:carburettors
404:Fuel system:
403:
390:
374:
367:Displacement
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356:
347:
338:
327:
324:
323:
248:BAT Basilisk
226:Applications
218:Dragonfly IA
194:
182:
177:Bill Gunston
174:
147:
143:cooling fins
124:
106:
104:
95:Number built
15:
426:Performance
415:2 oil pumps
413:Oil system:
212:Dragonfly I
188:of its own
50:aero engine
775:Categories
493:References
421:Air-cooled
392:Valvetrain
385:Components
376:Dry weight
190:crankshaft
168:, and the
126:ABC Motors
86:First run
70:ABC Motors
21:Dragonfly
730:Dragonfly
325:Data from
197:Armistice
76:Designer
755:Scorpion
750:Mosquito
472:See also
207:Variants
141:-plated
134:ABC Wasp
164:), the
745:Hornet
735:Gadfly
725:100 hp
656:
631:
358:Stroke
139:copper
99:1,147
47:Radial
720:60 hp
715:30 hp
498:Notes
406:Twin
339:Type:
162:Snipe
89:1918
43:Type
760:Wasp
740:Gnat
710:8 hp
654:ISBN
629:ISBN
349:Bore
105:The
696:ABC
614:doi
484:of
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641:.
569:^
396:3
688:e
681:t
674:v
660:.
635:.
620:.
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
