Cowl Flaps in General - Dora start up procedure

[Kratzer]

This came up in a discussion elsewhere...

Would the cowl flaps be opened at times other than start up?  Once flying, wouldn't the air flow and low air temp. at altitude keep the engine cool, and the flaps would be closed 95% of the time?

Does anyone have any guidelines for the Dora on how this actually would be used?

What are the other benefits of having them open/closed?

Thanks!

[Kratzer]

...and how were they controlled on the dora?  Just a switch that either opened or closed them?

[Kratzer]

and does anyone have pictures of a Dora in flight?

[mauser]

Sorry Kratzer, I don't have an answer to your questions on the cowl flaps, but your last post about a pic of an in-flight Dora caught me.  I've almost come to the conclusion that were were none, since I haven't seen any.  I have the Green Hearts book and several other books, and the most I've seen is a pic of them about to rotate on take off or a blurry pic of one strafing.  I came to my own conclusion that by the time the Dora came out no one in their right mind would go up for a nice photo shoot whilst the Allies had nearly every usable airfield under their watchful eye. This is my own conclusion though, It'd be cool to see an in-flight pic though.

mauser

[GRUNHERZ]

They have to be at-least somewhat open for flight, otherwise there wont be any airflow through the cooling system. They were probably automatic as they were on 109s and as most things on 190s were anyway. Plus its probably safe to say they also had a manual override to close the flaps for minimum drag but only used in short ememergency periods or engine could seize due to overheat- again 109s had a simmilar feature.

[fats]

There's a picture of a Fw 190D diving under a bomber that has just released its bombs, pictured with the bomber's camera.

You're right though, no neat flying photos taken by other Fw 190Ds as far as I have seen.


// fats

[flakbait]

Cowl flaps are opened on the ground and during low speed flight. They give only extra cooling by giving you a huge open hole for hot air to exit. They also create an unreal amount of drag. During takeoff you usually shut the cowl flaps just after throwing the gear level to the up position. Open them up nice and wide for landing so the engine doesn't cook itself. Head to Zeno's site and watch any of the bomber training films. More than once they state open the cowl flaps for landing and during ground ops. Unless the engine overheats in flight, keep them shut.

On Joe Baugher's site under the B-29 section he gives this little tid-bit about them:

 

Crews soon learned that the key to keeping the engine head temperature within tolerable limits was to have as much airspeed as possible when they became airborne on takeoff. During takeoff, they used the entire runway and reached a speed of 140-145 mph to become airborne in a fairly nose-low attitude. After takeoff, they would stay fairly low for a rather long time, with no effort to climb. This was done to attain the climbing speed of 200 mph as rapidly as possible. As the airspeed built up, the flight engineer would start to squeeze the large cowl flaps closed, since the key to controlling the head temperatures was airspeed, and as the speed got higher, cowling flaps in the extended position produced more drag than cooling.

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Flakbait [Delta6]
Delta Six's Flight School
Put the P-61B in Aces High
"With all due respect Chaplian, I don't think God wants to hear from me right now.
I'm gonna go out there and remove one of His creations from this universe.
And when I get back I'm gonna drink a bottle of Scotch like it was Chiggy von
Richthofen's blood and celebrate his death."
Col. McQueen, Space: Above and Beyond
 

[Kratzer]

Hey - Great info flakbait - can you drop a link to that site?

Thanks!

[flakbait]

Here ya go:
 http://home.att.net/~jbaugher2/b29_9.html

It's about Operation Matterhorn (B-29's bombing Japan). Read the entire thing to get a good sense of what the crews went through. Here's the entire quote about cowl flaps and heat problems:

 

Many of the accidents which plagued the B-29s operating out of China and India were caused by engine fires, which were still a problem in spite of massive efforts to correct them. The cylinder head temperature gauges were red-lined at 270C. The combination of very high ambient ground temperatures (100 to 115F) and the inadequate cooling system of the engines would often result in head temperatures exceeding 310C during and immediately after takeoff. The high temperatures often resulted in the evaporation of valve stem lubrication, which could cause the valve to break off. The broken valve would then blow the cylinder off, which inevitably resulted in a fire.

Crews soon learned that the key to keeping the engine head temperature within tolerable limits was to have as much airspeed as possible when they became airborne on takeoff. During takeoff, they used the entire runway and reached a speed of 140-145 mph to become airborne in a fairly nose-low attitude. After takeoff, they would stay fairly low for a rather long time, with no effort to climb. This was done to attain the climbing speed of 200 mph as rapidly as possible. As the airspeed built up, the flight engineer would start to squeeze the large cowl flaps closed, since the key to controlling the head temperatures was airspeed, and as the speed got higher, cowling flaps in the extended position produced more drag than cooling.

Imagine trying to fly a B-29 on a blown engine with our flight model!! Oops, that's another gripe  


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Flakbait [Delta6]
Delta Six's Flight School
Put the P-61B in Aces High
"With all due respect Chaplian, I don't think God wants to hear from me right now.
I'm gonna go out there and remove one of His creations from this universe.
And when I get back I'm gonna drink a bottle of Scotch like it was Chiggy von
Richthofen's blood and celebrate his death."
Col. McQueen, Space: Above and Beyond
 

[Kratzer]

Hey fats -

Do you have a link to that picture online?