Radial engined fighters

[tanktastic43]

A bit of info required, if anyone can help it would be appreciated.

Thanks in advance.

Were there any radial engined fighters that fired through their nose?
That is, with the gun barrel going through the spinner, Me109 or Aircobra style.

Or was such a thing not possible?

tt43.

[rickshaw]

Difficult but not necessarily impossible.  What must be understood is that the centre of a radial engine is usually filled with the drive shaft, which the cylinders drive.  However, if you offset the radial engine from the propeller, you could have a gun firing between two cylinders and then through the propeller boss.

[kitnut617]

If you had a single row radial you can set a gun barrel in between a pair of cylinders and then through a spinner as Brian has just said.  If you were to use a two-row radial (or three or four-row) it's impossible to do that as the cylinder row that is behind the first row is placed in the space between a pair of cylinders (for cooling purposes). However, there were liquid cooled radials which had all the cylinder rows lined up exactly one behind the other.

The Airacobra though is not a good example, as the engine for that aircraft is behind the cockpit.  But keep in mind no aircraft had a gun firing through the engine because they all have a crankshaft, the guns were all mounted in the 'Vee' of the cylinder banks then protruded through an offset spinner.

But if you wanted a 'what-if' type of engine that could fire through the engine, I would suggest a 'Wankel' type engine, these actually don't have a traditional type of crankshaft, it being just a straight shaft (which could be hollow) with offset 'cam-lobes' attached to it. These 'Cam-Lobes' are really a fixed type of piston and in all respects it could be termed as a radial too, as the combustion chambers are set radially around the crankshaft (most have three chambers).

[pyro-manic]

I seem to recall that the Boeing P-26 had the machineguns firing through the engine, between the cylinders. Not through the spinner, but through the engine (and the prop, requiring synchronisation obviously).

[sandiego89]

I seem to recall that the Boeing P-26 had the machineguns firing through the engine, between the cylinders. Not through the spinner, but through the engine (and the prop, requiring synchronisation obviously).

Correct on the Peashooter, syncronized 7.62's between the upper cylinders.

I see a gun going through the center of a complex radial close to impossible due to the crankshaft and the drive shaft arrangment- but we are in WHIF.  As mentioned  below the offsets could work: mount the radial further back, and have the cannon go though a hollow drive shaft and through the spinner center- like the P-39- the gun would need to be ahead of the engine, not go through the center.     

[deathjester]

How about a Rotary engine, as in First World War fighters?

[kitnut617]

I seem to recall that the Boeing P-26 had the machineguns firing through the engine, between the cylinders. Not through the spinner, but through the engine (and the prop, requiring synchronisation obviously).

You could say the same about a Gladiator Alun, the fuselage guns fired between the cylinders, but I wouldn't use the term 'through the engine'.

[kitnut617]

How about a Rotary engine, as in First World War fighters?

That would work

[deathjester]

Well, in that case, could a Radial be made that develops the same sort of horsepower as, say, an R2800?

[kitnut617]

How about a Rotary engine, as in First World War fighters?

That would work

Actually, it won't work (sorry, my bad), have a look at this diagram



You still have conrods connected to a 'U' shape and they have to pass through the 'U' to work

[tanktastic43]

Thank you all for your input. 

tt43.

[Hobbes]

Well, in that case, could a Radial be made that develops the same sort of horsepower as, say, an R2800?

You mean a rotary? It'd be very difficult. http://en.wikipedia.org/wiki/Rotary_engine The entire engine block has to spin, an R2800-sized rotary would have huge gyroscopic effects. Also, the engine block is suspended by the crankshaft. A four-row radial would put huge stresses on the crankshaft.
Setting the fuel/air mixture is fiddly. It's also inefficient, so it'd use more fuel. You can't use a turbocompressor (the exhausts rotate as well, no way to connect them to the stationary part of the engine), and the intake plumbing is rather complex and may not react well to supercharging. Basically you'd be putting the overpressure into the crankcase so you'd have to seal it (the crankcase rotates so it's a complex seal).

[gofy]

I heard that some FW-190's had spinner mounted guns (but those might have been Doras)

Mr. Gofy

[rickshaw]

I heard that some FW-190's had spinner mounted guns (but those might have been Doras)

Mr. Gofy

They were.  Doras and Ta152s of course used inline engines with annular radiators which made them appear to be radial powered.  As has been mentioned, the radial engined Fw190A,B,C,F,G models could not mount a engine cannon because there was no room in the engine bay for them (and the engine used, wouldn't allow it).

[Weaver]

Re the idea of fitting a radial with an offset reduction gearbox and lining it up with a gun barrel that sits in between the cylinders, the problem with that is that you'll probably get asymetric cooling, particularly in the "shadow" of the gearbox, and of course, you can't fix that with a crankshaft-mounted fan (FW-190 style) because that would interfere with the gun barrel just like a prop.   

But if you wanted a 'what-if' type of engine that could fire through the engine, I would suggest a 'Wankel' type engine, these actually don't have a traditional type of crankshaft, it being just a straight shaft (which could be hollow) with offset 'cam-lobes' attached to it. These 'Cam-Lobes' are really a fixed type of piston and in all respects it could be termed as a radial too, as the combustion chambers are set radially around the crankshaft (most have three chambers).

Not saying it's impossible by any means, but one thing to bear in mind is that a lot a Wankels use a hollow "crankshaft" as a means to cool the rotors. Rotor cooling is a big deal for Wankels because at least one face of the rotor is exposed to combustion heat pretty much all the time, as opposed to a conventional piston which is only exposed to it 25% of the time (4-stroke) or 50% (2-stroke). Also, the Wankel's rotor is entirely enclosed in a combustion chamber with seals on all sides, which makes it hard to duct a cooling fluid of any sort to it: you can't squirt oil on the underside of it like you can with a piston, for example. Just about the only access to a running Wankel's rotor is down the middle of the "crankshaft", and most designs pipe either air or oil down it.