Yes, of course a radial fan is most efficient at forcing air sideways, like the interior blowers in the DS.
I believe it is the depth, steep angle and shortness of the 2cv blade design which assists in the direction of air.
I always thought that adding a cone onto the end to complete the prop would be better!
A radial fan would be perfect at cooling a 2cv motor, if it weren't for that bloody oil cooler!

Harley

Harley,
Yep, a radial fan plus the oil cooler in its normal position wouldn't work too well...

Anyway, has anyone mentioned 'swirl' yet?
That's the tendency for the air flow downstream of an axial fan to 'corkscrew', which Citroen recognised and addressed; it's why the fins in the oil cooler are set at an angle and why older metal engine cowlings had a 'scoop' fitted on the nearside to redirect the air upwards.
That second detail was deleted once those perishing accountants spotted it...

Ken

@ Aircon, it may be swicthed on in the cab, but the pump does not operate all the time ie it has a duty cycle.

The pumps, include a thermo cut out on the pumpbody and in the live feed.
Alas I don't currently use that part of the pump body.
Mark 3 yet to be built.

my 2litres/sec

I don't think it is 'corkscrew' in this case; it is more cooling surface area at same depth...... putting them on an angle..

lpgo,
if that was true, maybe they could have angled the fins in the other direction?
I'm happy to accept Rolls Royce's analysis, which might well see 'open rotor' aircraft coming back into service in the near future...

Rotational.
The torque input into the propeller has to be reacted by the air, resulting in rotational flow or swirl in the propeller wake, which is lost energy.
The use of a second propeller (contra-rotating) to capture this swirl flow allows the overall efficiency to be significantly improved whilst maintaining a propeller diameter that can be integrated with the airframe.

Full story here, which mentions testing already carried out at DNW in the Netherlands...
http://aerosociety.com/Assets/Docs/Gree ... Taylor.pdf

Bunch on nannas we are!
As AZS wrote

They are just his opinions, it just so happens that his opinions are correct!.
I see what you mean about the angle fins now Ken, I always assumed it was 'just' for more surface area as Geo mentioned, but given the direction of the fans deflection of air it would not be efficient if the fins where laid in the other direction.
Deflection of air is the terminology I should have been using instead of "push it sideways"
THere is a good pic HERE, fig 1 on page 1 which shows the angle of deflection the air flow takes through a fan.
This gives an idea of deflection and turbulence.

Best thread in a while! already forgotten more than I have learnt.
Interested to see your mark III clutch fan Pete

Harley

re HP gain by removing fan
The 5-stage tuning manuals published in the 1950s for the 1.5l Morris xpag engine (Riley, MG TD/TF) recommended removing the fan if you were confident of averaging speed above 40mph - for a gain of 1bhp. If you went all the way through the stage-5 tune you could wring 100bhp from the 63hp xpag.

Similarly, with the 4.5l 8 cylinder (65hp) side-valve ford mercury engine (1930s-1950s), Allard considered removing the fan would bring an extra 4hp. But they would overheat - as mentioned in the Chuck Berry song "Maybellene" when he is racing a Cadillac Coup de Ville over a hill.

+1

I think it is a real debat here, Ken like to tease you all the time, I think it is working already

Ofcourse theres a corkscrew there and also the old engines have wings inside to get the airstream even more efficient. But theres also the advantige of more cooling surface....


And I'm difinitly going to try a C5 fan an study things.....
As I said before I think the problem is at high speed the electric fan is blocking part of the airflow so the engine is still going hot.

Another thing is that nobody has the courage to cut the shaft of the crankshaft so the fan can go into the place the normal fan sits, I think this also has a big gain of efficiency...


Love you GUYS... peace....

Geo.

reading Ken's information :
so if you want to use an electric fan on your 2cv, better use 2 electric fans - one directly mounted after the other (have to be shallow ? if this is the right word - undeep models) with oposite rotating directions - because of the increase of efficiency smaller DC-motors kan be used, though you would need 2 motors .... and perhaps have to cut the top of crankshaft to create extra space for the 2 fans. mounting of the oilcooler infront of the fans optional ??
... do not hesitate to comment ....

The standard fan works.