Roland C.II exhaust

[IanB]

Hi all,
A quick question about the exhaust fitted to the early Roland C.II - I have seen pics that clearly show the front to be open, the top is presumably the exhaust exit, so that is also open, but what about the narrow rear end? Was that also open or was it blocked off? While I'm here, what was the point of the opening at the front?

Thanks for any help!

Ian

[ALBATROS1234]

often wondered those things myself.

[Dave in Dubai]

From an aerodynamic point of view, I would think the air-flow through the front and up through the exhaust would help to create a more efficient way of "pulling" or entraining the exhaust gases through the exhaust pipe after combustion.

It was probably an early attempt to improve volumetric efficiency before superchargers came on the scene for aero-engines much later.

[Dave in Dubai]

Good point Justin.

In addition , another effect of the upwards flow of the exhaust would be to keep the hot exhaust gases away from the wing structure which is very close, esp to the last couple of cylinder exhaust stubs, leading into the ocarina.

As you point out, the lack of visible exhaust staining on contemporary photographs, tend to indicate that the designers got their aerodynamics  correct in this respect.

Here is a plan view of the WNW Roland CII, to illustrate the geometry involved.



If the exhaust gasses were led away under the starboard wing, then there would have been problems with the efficiency of the starboard "ear-type" radiator. The best solution was to take the exhaust gas up and away from the starboard wing root.

[IanB]

Thanks guys, I had a feeling that it may be an effort to help "suck" the exhaust gases out, but wasn't sure. It does make sense though!
 I did actually find a pick in the Datafile (pic 21 on page which shows clearly that the rear end was closed and rounded off.

Ian