View Full Version : Prop pitch and Radiator settings

11-15-2004, 11:11 AM
Does anyone know of a good resource to clue me on on the proper pictching of my prop and how to use my radioator setings? I see that I can change these settings while I'm flying, but I don't know what increaseing/decreasing does.

11-15-2004, 11:37 AM
This has been gone around several times.

However what you do depends on how realistically you want to operate. This IS a GAME.

IRL... Cooling of radial engines was achieved through adjustable cowl flaps. Generally open all of the way for taxi, takeoff and landing, partially open for climb and as necessary for cruise, closed for descent. The object is to keep cyl head temps in the proper range (see guage).

Props, you are really setting the prop to maintain a constant engine/prop speed. Heading from max to the '0' setting is reducing engine RPM. Throttle sets manifold pressure (see guage) and prop sets RPM. Both go to make up a proper power setting. Generally for Takeoff, max RPM (2800 RPM for F4U and perhaps 55" or so), reduce to 2600 for climb, and 2200 or lower for cruise. Go back to max RPM for landing in case of a waveoff.

It's a lot more complex than all of that, but that will get you headed in the right direction.

Max power will always be delivered at max RPM with max manifold pressure, always.

11-15-2004, 11:05 PM
Dont know about that..I thought radiator should be closed at take-off and landings..you dont want rocks, dust,or debris in the radiator.
As oxigen fades climbing you compensate opening radiator.You want speed to run you close it and watch temp gauges.Also for speed at low level mixture 120% helps a bit. If you idle for long time on runway you keep radiator open and close it when you rolling. That,s my opinion but i,m not expert.

11-15-2004, 11:14 PM
well... you want the cowl flaps/radiator full open on the ground or whenever you are at max throttle. I believe you are supposed to open the cowl flaps fully on landing approaches too, in case you have to go to max power and abort the landing.
No debris will get into the rad. when its flaps are open...at least, not to the point of doing harm..these are not jet engines.

you want to set the cowl/flaps to about 5-6 on the dial when in cruise...I never fully close them unless the plane I am 'flying' has the 'closed/auto' setting.

Prop pitch/engine RPM adjustment is for reducing strain on the engine in cruise...just reduce the pitch percentage to 90-95 in cruise.

Some guys use it as a brake to slow the engine down for landing approaches but that is not an accurate usage of this control feature. It just works in the sim and there is no crew chief to put a boot in yer A$$ for tearing apart his engine after you land.

11-15-2004, 11:22 PM
Dust, debris, dirt, sand can, to a certain degree, be cleaned and only really degrade engine performance over time ... but a seized engine due to overheat from closed cowl flaps will kill the pilot right then and there.

If you look at any WW2 photo of a radial engine aircraft taking off, they have their cowls WIDE open ... whether from a carrier or dusty Henderson field in the Fall of '42. Typically you closed your cowls as you eased off on your climb and reached the colder air at 10k feet and above.

The poor, dusty conditions at Pacific airfields, particularly at Rabaul for the Japanese, contributed to huge aircraft attrition ... the average ground-based squadron in the Pacific was lucky to have 75% of its aircraft ready to fly at any given time, and dust/dirt in the airplane's mechanisms was a primary culprit for this downtime. The fact that American airmen and ground crews were experienced working on cars and tractors gave them a huge advantage over highly specialized Japanese mechanics when it came to repairing/modifying and rigging engines and mechanical parts to make aircraft flyable, and was a huge reason why the U.S. gained the advantage in the air over time.


11-16-2004, 04:09 AM
@ ThunderVipor
This might help http://people.ee.ethz.ch/~chapman/il2guide/cemguide/intro.htm