| The Breakroom > The Water Cooler |
| Historic Aircraft: Sopwith Camel & Spitfire |
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| AdeV:
Matthew - what I mean is, when the engine is not running, the (leftover) oil tends to drain to the bottom of it; which can cause plug fouling. Yes, when the engine is running, there is no such thing as "the bottom cylinder". |
| Pete W.:
Hi there, all, I don't understand why rotary engines rotate! :bang: :bang: Please can someone explain to me why it's advantageous for aero-engines to rotate the cylinder assembly rather than the crankshaft? Is it to do with weight or smoother torque or simplified valve-gear or what? Please be patient and gentle with my ignorance - I'm not well-versed in infernal combustion engine technology! :scratch: :scratch: Best regards, Pete W. |
| Pete.:
Only advantage I can think of is that the pistons and rods are not reciprocating as they do with a spinning crank. Might not have been easy to make a lightweight engine with strong enough conrods back then. |
| BillTodd:
--- Quote ---Please can someone explain to me why it's advantageous for aero-engines to rotate the cylinder assembly rather than the crankshaft? Is it to do with weight or smoother torque or simplified valve-gear or what? --- End quote --- Yes essentially. With old, low power, engines aircraft and their power units had to be as light as possible so there was a great advantage in using the weight of the whole cylinder block as a flywheel (instead of having an additional flywheel - the wooden prop being to light to act as a flywheel alone . Spinning the cylinders also helped to cool the engine (low efficiency means lots of heat ) The radial engine layout has a great advantage of being short and having all it's cylinders well exposed for air cooling. However, as the engines became more powerful and heavier, the spinning engine's gyroscopic effect started to become a problem for the airframe. Designers looked for alternatives - One solution the reaction-less engine, was to spin the engine one way and the prop the other coupling the torque to the airframe with a differential gear! Bill |
| andyf:
I know less than nothing about radial engines, but could it be that the rotating mass of the cylinder block (or perhaps I should say cylinder ring) meant that no heavy flywheel was needed? Andy PS Pete, I think the rotary engines under discussion have reciprocating pistons and conrods; see http://en.wikipedia.org/wiki/Rotary_engine. Were you perhaps thinking of the Wankel rotary engines ( http://en.wikipedia.org/wiki/Wankel_engine ) fitted to some Mazda cars from the late '60s onwards? |
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