Aircraft Radial Engines

[earl1937]

  In our game which we all enjoy, a number of aircraft have radial engines. Here are a couple of questions to help with your education on WW2 aircraft engines!

A- A radial engine has "coplanar" cylinders! What does that mean?

B- The engines on the B-29 have what is called, "4 stroke, 5 event engines"! What does that mean?

C- In the engines on a B-17, how many revolutions does the crankshaft have to make to complete the 4 strokes?

D- Which stroke has the "5th" event occur?

E- What is the "knuckle" assy on the C-47 landing gear and what is its function?

[GScholz]

A: All the cylinders are in one single plane on the crankshaft axis, and share a single crank.

B: To my knowledge all 4-stroke piston engines have 5 events. Intake, compression, ignition, expansion, exhaust.

C: For one cylinder it would take two revolutions, unless there was something really special about that engine. For all cylinders combined it would complete all for strokes (in different cylinders) in half a revolution?

D: The fifth event would be on the 4th stroke: Exhaust.

E: No idea whatsoever!

[icepac]

A.  It means the cylinders of each row share a "plane" which requires a master rod for each row of cylinders.

This means the 3350 has only two throws on the crankshaft.

B.  They are separating the ignition of the charge and it's expansion into two events though the piston only moves once for the two events.

C. If you are only counting cylinder 1, then it's two revolutions but, if you are specifying all 4 strokes being completed in all cylinders..............the question has to be more specific as to crankshaft position of each cylinder.

D.  Exhaust stroke.

E.  Knuckle is often interchangable with "spindle" since many knuckles have an integral spindle.

The knuckle converts from the vertical (or near vertical) of the strut to the horizontal such that a wheel can be fitted.

[earl1937]

A: All the cylinders are in one single plane on the crankshaft axis, and share a single crank.

B: To my knowledge all 4-stroke piston engines have 5 events. Intake, compression, ignition, expansion, exhaust.

C: For one cylinder it would take two revolutions, unless there was something really special about that engine. For all cylinders combined it would complete all for strokes (in different cylinders) in half a revolution?

D: The fifth event would be on the 4th stroke: Exhaust.

E: No idea whatsoever!

The "Knuckle assy", as it is referred to is part of the extension arms which lowers the landing gear. The extension arms extent 2 degrees beyond neutral or parallel  with each other, so as to not accidentally retract on touchdown or on a hard landing.

Each bank of cylinders has a "master" rod and the other rods connect directly to the master rod. Icepac is correct, on the R-3350 engine, it has only two "throws" on the crankcase.

It takes 2 complete turns to complete all 4 strokes of the piston inside the cylinder. Intake, compression, power, exhaust!

The 5th event occurs on the compression stroke and that is when the spark plugs fire

stroke one, intake is when the cylinder pulls in fuel and air, stroke two is when the piston moves back towards TDC and compress the fuel air mix, spark plugs then fire, which as the piston moves upward in cylinder, compress hot gases in cylinder, which then pushes piston back down in the power stroke. the 4th stroke is when the piston moves back to TDC again, forcing the exhust from the cylinder.

[Devil 505]

The 5th event occurs on the compression stroke and that is when the spark plugs fire

That would be the 3rd event in the order of events. The cycle begins the piston at top dead center beginning the intake stroke. Thus, exhausting the combustion gasses out of the cylinder is the 5th event.

[earl1937]

That would be the 3rd event in the order of events. The cycle begins the piston at top dead center beginning the intake stroke. Thus, exhausting the combustion gasses out of the cylinder is the 5th event.

Just depends on how you want to describe the cylinder during engine operation! you are counting strokes as events, but the only event which occurs is when the spark plugs fire. The only reason the strokes are named is for bench test purposes only! If,, during the testing of a individual cylinder, the person testing has to ident the problem if he finds one, hence the naming of the strokes, and where the 5th event occurs.

[Puma44]

Earl, did you use the landing gear knuckle on the Mustang to mount it from the front of the wing?

[earl1937]

Earl, did you use the landing gear knuckle on the Mustang to mount it from the front of the wing?

Only way to mount that Mustang!

[Puma44]

I was pretty sure that would be your answer.

[lunatic1]

 

[Puma44]

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