Antares Models

[The Wooksta!]

Looks nowt like any radial I've seen:

[kitnut617]

Look at the second link that Ralf posted and you'll see that's what it ends up as Lee.

There's a number of these 'connected' Vee engines that while working very well as a Vee, they don't when connected in this arrangement, and that's with a common crank or with separate cranks.

BTW, the Vulture looked a bit like your pic, only it had four banks of cylinder heads.  There's a Wright engine called a Tornado (got a book on it) that does look like this though, this one had 42 cylinders.

[PR19_Kit]

Isn't that odd/even cylinder business something to do with the power strokes on an even numbered engine tending to energise vibration modes more easily than an odd numered number of cylinders? We covered that in auto Tech when I was doing my HND in the mid 60s and my lecturer was a little ahead of his time in saying there would never be any 5 cylinder car engines in our lifetime.

Was he ever wrong!

[kitnut617]

Looks nowt like any radial I've seen:

Also, that's because you're used to looking at air cooled radials Lee.  Which have staggered rows so that cooling air can get to the rear row of cylinders.  Four row aircooled radials were much more problematic to cool, whereas these liquid cooled radials didn't have to have the rows staggered with the plus side of making a common head for each bank.

Here's a Lycoming liquid cooled radial designed for the B-35 & B-36, notice the similarities  



And here's the Wright Tornado

[kitnut617]

Isn't that odd/even cylinder business something to do with the power strokes on an even numbered engine tending to energise vibration modes more easily than an odd numered number of cylinders? We covered that in auto Tech when I was doing my HND in the mid 60s and my lecturer was a little ahead of his time in saying there would never be any 5 cylinder car engines in our lifetime.

Was he ever wrong!

I think that was how it was explained to me Kit, only with a lot more technical stuff.

Back in the 70's, my boss had an Audi sedan (saloon) that had a V-5 engine, three ftowards the front and two back.  Honda raced a 990cc MotoGP bike for years using the same configuration, winning many championships with the bike.

[Hobbes]

Isn't that odd/even cylinder business something to do with the power strokes on an even numbered engine tending to energise vibration modes more easily than an odd numered number of cylinders? We covered that in auto Tech when I was doing my HND in the mid 60s and my lecturer was a little ahead of his time in saying there would never be any 5 cylinder car engines in our lifetime.

Was he ever wrong!

That sounded right to me, but Wikipedia offers this:

Four-stroke radials always have an odd number of cylinders per row, so that a consistent every-other-piston firing order can be maintained, providing smooth operation. This is achieved by the engine taking two revolutions of the crankshaft to complete the four strokes, (intake, compression, power, exhaust), which means the firing order is 1,3,5,2,4 and back to cylinder 1 again. This means that there is always a two-piston gap between the piston on its power stroke and the next piston to fire (i.e., the piston on compression). If an even number of cylinders was used, the firing order would be something similar to 1,3,5,2,4,6, which leaves a three-piston gap between firing pistons on the first crank shaft revolution, and only a one-piston gap on the second crank shaft revolution. This leads to an uneven firing order within the engine, and is not ideal. [1]

As for five-cylinder engines (again, Wikipedia):

The use of straight-five petrol engines in mass production cars only became truly viable with the advent of reliable fuel injection. A five-cylinder engine using a carburetor fuel system has an unavoidable problem in that the length of the inlet manifold between the carburetor varies too greatly between cylinders at the ends of the engine and those nearer the carburetor for reliable and consistent fuel delivery. Using multiple carburetors (two or three) always results in one carburetor feeding more cylinders than the other which also produces running and tuning problems

The Audi/VW V5 always felt 'wrong' to me somehow. A straight 5 seems a good compromise between the vibrations of a four-cylinder and the fuel consumption of a 6-cylinder (and they sound good).

[PR19_Kit]

Hobbes,

Yes, that's what I eventually recalled about the 2 cylinder firing gap. It was almost 50 yrs ago though. 

I had a Volvo 850 wagon for 2.5 years and it sounded tremendous, a lovely 'THRUM' as it accelerated through the torque peak, and it did a lot of that while I had it 

But odd numbered cylinder in-line engines need balancer shafts to rid themselves of the secondary torsional vibration modes, unlike a straight six which is in perfect balance all the time.