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Airflow under a cowling

I have to wonder, as I did higher above in the old posts, why more attention isn’t given to this topic. It’s not exactly difficult to create a “shape” under the upper cowling which does the right thing.

Then you could make the two front holes smaller and gain some extra speed.

My comment wasn’t a joke – it was exactly what was originally posted. Well, on my understanding of English, since coming to the UK in 1969.

Administrator
Shoreham EGKA, United Kingdom

Some time ago, I gave up trying to control the airflow through the innards of my PCs with a multitude of fans to keep the various bits cool, and resorted to a cutting-edge, innovative concept called water cooling. Now my PC runs cooler with a lot less noise than before.

I wonder if it is possible to apply this sort of radically new engineering to aircraft engines?

Last Edited by Cobalt at 03 Jul 21:38
Biggin Hill

Sure you can water cool aircraft engine – but until today most attempts in GA were not successful, just look at the many problems the liquid cooled Contis in the Extra 400 (and some other planes) had. And then think about the massive weight of such a system and all consequences. Some turbocharged airplanes are already too nose heavy.

There is some truth to the old rule that you don’t “air cool submarines and water cool airplanes”.

The trouble, @Peter, is that you write a long sardonic and pedantic post, but you have failed to be sufficiently pedantic about what I wrote.

You have taken what I actually wrote:

most of the cooling air in a horizontally opposed cowling is flowing forward

And interpreted it as:

most of the air in a horizontally opposed cowling is flowing forward

There is a very significant difference in the two sentences.

Think how much time you could have saved if you had spotted that

EGKB Biggin Hill

I don’t agree; most of the cooling air is moving downwards, because there is no other way for it to go if it is to get through the cylinder fins.

I suspect the point Deakin was trying to make is that a lot of the air entering the two front holes (at a considerable cost in terms of drag) is wasted, and if one could make it work harder (and get it going downwards in a more organised manner) the two front holes could be a lot smaller and cost a lot less in drag.

I have now merged the two essentially identical threads.

Sardonic and pedantic ?

Administrator
Shoreham EGKA, United Kingdom

Lol Cobalt I have just read this thread all the way to your post, hoping to garner some useful hints for optimizing my … tadaaa… WATER-cooled Continental.

The name is TSIOL-550C
If you googlef Extra400 you will see that the cowling has a huge inlet for the coolant radiator and is literally full of additional air intakes.
And yet it is not enough: Extra came up with a SB suggesting a mod to blow some air on the exhaust manifolds.

Why I need a solution?
> Water cooling the “jugs” is nice, but the rest of the engine (especially around the exhaust stacks) is not getting the benefit of the inter-cylinder airflow. I have already seen a part of MY engine’s exhaust melted and deformed. Yikes. Just bought an 8 channel temperature logger and will start examining what is going on asap.
> This is a heavily turbocharged engine (MAP up to 40 inches) and the limiting factor is the turbine inlet temperature – I am hoping to get more power for less fuel by cooling the exhaust system per Extra’s SB.
The turbo is “fed” from these, so shedding some heat before entering the turbine is what I want. Again, measurement will help understand and fine tune the SB’s directions for a proper solution.

Summary: Water cooling the cylinders is fantastic. But it leaves a BIG list of other items needing TONS of cooling.

LSGG, LFEY, Switzerland

Peter wrote:

I suspect the point Deakin was trying to make is that a lot of the air entering the two front holes (at a considerable cost in terms of drag) is wasted.

The point he (or rather Walter and George) are making is that the air enters the edges of the cowling and has negligible cooling effect, bounces off the firewall and is turned inwards and forwards. Cooling air is therefore coming forward over the pots to cool them. The point about wastage is ancillary but also true. If air could be caused to flow in the neat way assumed in the diagram you Googled, it would be hugely more efficient.

EGKB Biggin Hill

Peter wrote:

Sardonic and pedantic ?

Ah! This is my just punishment?! Funny, but a little sad.

EGKB Biggin Hill

This blog contains very interesting analysis of engine cooling and some practical solutions.

Thanks for posting that Robin253. Even with google translate that is a great read.

I wonder how he could have done that on a Jodel (which is where his “Jojo” comes from) which I believe is a certified plane.

Administrator
Shoreham EGKA, United Kingdom
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