P-38 MANEUVER Flap 8 Degrees?

[Randy1]

I've done quite a bit of reading old HTC forum post and other sources including the online manuals for the P38 related to the Maneuver lap setting on our P38s.

The manual posted on the AH wiki says 1/2 flaps is maneuver flap.   I have also seen post that suggested that it is 8 degrees and is modeled in AH as the first notch of flap or first press of the key.

My guess from my reading is the flap lever "Maneuver" setting is 8 degrees of flap and the manual suggest up to 1/2 flaps could be used for maneuvers.  Although closely related the actual setting is confused with the manual general use of the word maneuver.

Anybody know what angle the flaps were at on a real P38 when the flap lever was set to Maneuver"?

[FLS]

The P-38 manual says the maneuver setting is the flaps half extended, that's more than 8 degrees.
 
For most aircraft the first notch of flaps is often considered the maneuver setting but which flap position gives the best turn performance varies with the aircraft model. The degree of flap extension in a fight varies from none to full so the term should not be taken too literally.

[Randy1]

The P-38 manual says the maneuver setting is the flaps half extended, that's more than 8 degrees.
 
For most aircraft the first notch of flaps is often considered the maneuver setting but which flap position gives the best turn performance varies with the aircraft model. The degree of flap extension in a fight varies from none to full so the term should not be taken too literally.

I found an old post where AK-AK said it was 8 degrees and showed a drawing.

[FLS]

The manual is clear. Without reading Ack-Ack 's post I can't tell what you're confused about. It seems like he's describing the first notch of flaps in AH. The real P-38 did not have 5 settings. It had full up, full down, halfway (maneuvering), and anywhere else you wanted to put them within their range of movement.

[Ack-Ack]

That would be from this site.

http://www.kazoku.org/xp-38n/articles/p38info.htm

This is an underside picture of the maneuver flaps deployed.


Shot of flying P-38 with maneuver flaps deployed.


ack-ack

[FLS]

OK I was confused.    I was thinking 8 degrees was the first notch of flaps in the AH P-38 but they are halfway out.

The illustration in the article ack-ack linked shows 4 flap positions with the first being "maneuver". This is clearly not half deployed and appears to be incorrect. The second position in the illustration matches the photographs. Now I'm wondering which position in the article is 8 degrees?

[earl1937]

OK I was confused.    I was thinking 8 degrees was the first notch of flaps in the AH P-38 but they are halfway out.

OK, now I am confused by what you guys are saying! Are you saying that I have the option of deploying 1/2 flaps in the 38 at 300 MPH IAS?  Are do you mean that while maneuvering in combat and I get below a certain speed, I can then deploy the flaps 50%. I thought you had to be in the 150 to 175 IAS range before my flaps were useable!  If what you are saying, then the maneuvering flaps would be useful in dive bombing attacks also to keep from compressing so easily!

[FLS]

The pilot manual says full flaps are limited to 150 mph IAS, maneuver flaps (half down) are limited to 250 mph IAS.

[Randy1]

Well, I am still confused.  From Ak-AK's link. 

The MANEUVER setting was introduced in mid-production of the F model (F-15).  The MANEUVER setting pitched the flaps down 8 degrees and were often used for take-off and more importantly, combat, to decrease turning radius.  Thus, this setting of the main flap system was sometimes called "COMBAT" flaps. 

Gentlemen, you are assuming facts that do not happen in AH.

We simply put the degrees and coefficients in for each flap stop.

So what degree is displayed may or may not match what the real plane displays for degrees for the same coefficients. For instance the first stop of the p38 may be displaying 10 degrees, but really be the 8 deg coefficients.

The only thing degrees really do is control the rate at which the flaps move. We put in a degree per sec rate, and then each flap stops degrees.

HiTech

  That statement gave me even more confidence HTC worked hard to model in every detail they could and still make the game user friendly.  This was in response to someone who had questioned the use of the button push to model flaps.

I am not arguing here just confused.

[FLS]

The article seems to be mistaken about the flap position. First notch of flaps is 8 degrees from Hitech's quote. Second or third notch is the maneuver setting. The graphic may not match exactly but looking down at the flaps you can decide when it looks about halfway out. The photo of 985 looks like 2 notches of flaps in AH.

[Randy1]

From
http://www.warbirdsresourcegroup.org/URG/p38_variants.html

From the P-38F-15 model onwards, a "combat maneuver" setting was added to the P-38's Fowler flaps. When deployed at the 8° maneuver setting,

[Randy1]

Now . . . the rest of the story.  I really enjoy trying to understand what was going on in the design meeting back then.

After finding a 1933 NACA paper on split flaps, it became clear why 8 degrees was selected as the "Maneuver" setting for the P-38.  There is a much later paper I think in 1944 which pins down all the basic flap types we use today and it covers dive flaps as well.  The war offered tremendous advances in aeronautics knowledge without question.

Some will say nay these are hybrid Fowler flaps which is right but in that the first 8 degree tilt they are split flaps since they are yet to slide back.

Split flaps( a Wright brothers invention I think) are pretty good flaps until around 12 degrees.  After 12 degrees more or less, the lift addition due to the flaps goes negative but drag continues to go up.  On the P38, after eight degrees deflection, the Fowler part plays in letting  the flap slide back as well as turn down altering the airfoil shape greatly improving lift but at a higher cost in drag over the first 8 degrees.

At 8 degrees flap, you have the best efficiency for lift addition verses drag.  Not the peak lift which happens at 50% flaps best I can tell but at 8 degrees the biggest bang for the buck you might say. After 50% flaps, some lift might be gained but the intent of the flap at this point is to increase drag dramatically.

I am pretty sure of this but I am a Mechanical Engineer, not an Aeronautical Engineer.  Interesting no matter how you look at the P38.

[Ack-Ack]

Flap diagram for a P-38G.



ack-ack

[FLS]

Nice pic. It looks like the illustration in the article but the correct flap position is marked maneuvering.

[Randy1]

Nice pic. It looks like the illustration in the article but the correct flap position is marked maneuvering.

The illustration is from an R/C modeling magazine.  My guess is the scale modeler read the same statement in the training manual.