Subject:
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Re: Rotary Engine Help
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Newsgroups:
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lugnet.build.military
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Date:
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Thu, 1 Nov 2001 13:37:34 GMT
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Viewed:
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268 times
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In lugnet.build.military, William R. Ward writes:
> One of the weaker spots in my PB4Y-2 model is the engines. They are very
> basic. I'd like some advice on how I can make more realistic engines.
>
> The real plane has four radial engines, with air scoops above and below, for an
> elliptical shape. I modeled this using simple 45 degree slopes and inverse
> slopes with simple bricks between, with a Technic 1x2 to mount the propeller.
>
> I don't know much about how radial engines work - at the BayLUG meeting, Mark
> Benz gave me four Technic gears (the kind with 24 bent teeth, for meshing at
> right angles with other gears) and told me to put them on the propeller shaft.
Bill,
In a radial engine, the cylinders are just arranged in a circle around the
crankshaft, and the propellor is either attached directly to the crankshaft,
or attached via a gearbox. I think most WWII radial engined airplanes had
the propellors attached directly to the crankshaft. So, with a 13 cylinder
engine, some cylinders are compressing, some igniting and providing power,
some exhausting, and some intaking. The sparkplugs and valves are near the
top of the cylinder, at the outside diameter of the engine. The engines are
aircooled, so they have lots of cooling fins.
The toughest part in Lego is that radial engines have an odd number of
cylinders per bank, 7, or 9, or 11 or 13 (IIRC). I found it hard to arrange
pieces to get the correct number of cylinders, so you may have to use 8 or 12.
For Lego Models, the Bi-Wing Baron, http://guide.lugnet.com/set/5928, has
four cylinders, but does suggest a radial engine.
The rotary engine is even stranger, and died out in the 1920s, IIRC. In the
rotary engine, the crankshaft is stationary and the cylinders rotate around
the crankshaft. The propellor is attached directly to the cylinders. A
rotary engine had so much rotational inertia that it made for a tricky,
nimble plane (Left to itself, rotary planes would bank and turn to offest
the engines rotational movement. Taking your hands off the controls on a
rotary plane could be lethal). The mechanics are even trickier than a radial
engine.
I built a model of a DH2, with a rotray engine,
http://www.frontiernet.net/~ghaberbe/legodh2.htm . I should take better
pictures, this MOC still exists.
Thanks,
George
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Message has 1 Reply:
 | | Re: Rotary Engine Help
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| (...) That's a pretty clever design. Maybe I can do something with that. (...) Another type of rotary engine? The one I know of is called the Wankel Rotary Engine, and is something completely different - it has no cylinders or pistons at all. I'm (...) (23 years ago, 1-Nov-01, to lugnet.build.military)
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Message is in Reply To:
| | Rotary Engine Help
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| One of the weaker spots in my PB4Y-2 model is the engines. They are very basic. I'd like some advice on how I can make more realistic engines. The real plane has four radial engines, with air scoops above and below, for an elliptical shape. I (...) (23 years ago, 1-Nov-01, to lugnet.build.military)
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