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General Forums => Aircraft and Vehicles => Topic started by: Randy1 on August 27, 2014, 04:41:57 PM

Title: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on August 27, 2014, 04:41:57 PM
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"?
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on August 27, 2014, 05:24:49 PM
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.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on August 27, 2014, 09:15:11 PM
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.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on August 27, 2014, 10:25:28 PM
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.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Ack-Ack on August 28, 2014, 01:40:49 AM
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.
(http://www.aero-news.net/images/content/military/2007/LSFM-pb4y-flaps-0707m.jpg)

Shot of flying P-38 with maneuver flaps deployed.
(http://www.456fis.org/THE%20P-38/P38.750pix.jpg)

ack-ack
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on August 28, 2014, 03:56:51 AM
OK I was confused.  :lol  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?
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: earl1937 on August 28, 2014, 04:57:20 AM
OK I was confused.  :lol  I was thinking 8 degrees was the first notch of flaps in the AH P-38 but they are halfway out.
:airplane: 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!
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on August 28, 2014, 05:26:09 AM
The pilot manual says full flaps are limited to 150 mph IAS, maneuver flaps (half down) are limited to 250 mph IAS.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on August 28, 2014, 06:33:14 AM
Well, I am still confused.  From Ak-AK's link. 

Quote
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. 

Quote
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.

Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on August 28, 2014, 06:52:21 AM
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.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on August 28, 2014, 07:13:22 AM
From
http://www.warbirdsresourcegroup.org/URG/p38_variants.html (http://www.warbirdsresourcegroup.org/URG/p38_variants.html)


Quote
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,
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on August 28, 2014, 01:42:28 PM
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.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Ack-Ack on August 28, 2014, 02:27:23 PM
Flap diagram for a P-38G.

(http://static.rcgroups.net/forums/attachments/1/4/6/2/a2759239-214-P38%20flap%20track.jpg)

ack-ack
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on August 28, 2014, 02:42:42 PM
Nice pic. It looks like the illustration in the article but the correct flap position is marked maneuvering.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on August 28, 2014, 03:12:55 PM
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.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on August 29, 2014, 07:26:07 AM
I am not sure how authoritative of a source Joe Baugher is considered on this forum on the P-38 variants but this is from the THE 456th FIGHTER squadron web site

The P-38F-15-LO introduced combat flaps which could be rapidly extended to 8 degrees during maneuvers to tighten the turning radius.

The single manual statement is the only source I can find saying 50%.  The introduction to the manual clearly states the information was not to be used for anything but information.   All specific technical information came from another source

From the all the technical information I can find 50% flap would be a poor choice for an enhanced maneuver setting.  The 8 degrees offered enhanced lift without a large increase in drag as is found in Fowler flaps at 50% deflection.

A fixed setting of 8 degrees would offered the pilot a do all setting without having to set the flaps by flap indicators.  This was especaily helpful since the flap handle was on the right side I would think.

Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Ack-Ack on August 29, 2014, 12:24:52 PM
Yeah, the P-38L manual I have also mentions 1/2 flaps for the Maneuver setting which is at odds with everything else I've read.  I've got some other manuals for the earlier Lightning series and I'm going to check to see if those say the same thing. 

ack-ack
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on August 29, 2014, 12:44:39 PM
I'm certain the 8 degrees is a mistake.  In addition to the pilot's manual, Lockheed also stated the maneuvering setting was a half extension of the flaps. That would be about 20 degrees.

A deflection of 8 degrees is a normal first notch combat setting. The P-51 and P-47 both consider the first notch the combat flap position but they aren't fowler flaps which also increase the wing area. The P-38 could set 8 degrees based on the cockpit gauge or indicator pin. Pulling the lever to the maneuver setting set the flaps to half extended. In the AH P-38 the best sustained turn rate and radius is 3 notches flaps, 2 notches can be the same rate with a larger radius from the higher speed.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on August 29, 2014, 01:36:47 PM
I went through every manual I could find and I do have some interesting notes although not conclusive.  In landing instructions they say set flaps to Maneuver setting.  In another part of the manual mention 50% flaps as if they were two different settings.  They table list 50% flaps but never mention Maneuver setting.

I can not find the Lockheed documentation giving the Maneuver setting as 50% or 8%.

The information I have found weighs heavily toward the maneuver setting be 8%.  Only on general information document says 50%.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Ack-Ack on August 29, 2014, 01:40:13 PM
I'm certain the 8 degrees is a mistake.  In addition to the pilot's manual, Lockheed also stated the maneuvering setting was a half extension of the flaps. That would be about 20 degrees.

A deflection of 8 degrees is a normal first notch combat setting. The P-51 and P-47 both consider the first notch the combat flap position but they aren't fowler flaps which also increase the wing area. The P-38 could set 8 degrees based on the cockpit gauge or indicator pin. Pulling the lever to the maneuver setting set the flaps to half extended. In the AH P-38 the best sustained turn rate and radius is 3 notches flaps, 2 notches can be the same rate with a larger radius from the higher speed.

It is rather confusing.  In Flying American Combat Aircraft of WWII: 1939-45, Volume 1; Volumes 1939-1945 (page 65), a P-38 pilot mentions, "While on top of the peel-up, in a vertical bank almost on our back, we chopped throttles and moved the flap handle into half-flap position (maneuver flaps)."

ack-ack
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: bozon on August 29, 2014, 02:28:35 PM
I'm certain the 8 degrees is a mistake.  In addition to the pilot's manual, Lockheed also stated the maneuvering setting was a half extension of the flaps. That would be about 20 degrees.
From this discussion it sounds to me like "1/2 flaps" means "somewhere in between" and not exactly 0.5 of the max flap angle. The term half is often used in this inaccurate way - like when people say "here, take the larger half".

Also, half travel of the flap is not half the deflection angle. The Fowlers first move backwards out of the wing and then deflects, so perhaps 10 degree deflection is about half the time to deflect full flaps and hence the "1/2" reference - the pilot hears the flaps motor working for about half the time. I still think that the "1/2" term is very liberally used to described a state between the min and the max.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on August 29, 2014, 03:15:26 PM
I doubt they said half way and actually meant one quarter or one fifth.

The manual also states that half way is the max flap setting before you get more drag than lift.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Puma44 on August 29, 2014, 05:07:31 PM
From the pilot's perspective, its a physical setting that produces a configuration determined by the design engineers, flight test pilots, etc.  The actual degree setting of the flaps is really not a big deal, as long as the flaps go to the configuration they are commanded to.  
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on August 30, 2014, 10:16:40 AM
It is rather confusing.  In Flying American Combat Aircraft of WWII: 1939-45, Volume 1; Volumes 1939-1945 (page 65), a P-38 pilot mentions, "While on top of the peel-up, in a vertical bank almost on our back, we chopped throttles and moved the flap handle into half-flap position (maneuver flaps)."

ack-ack

AK AK, interesting.  We could be dealing with two possiable problems in trying to pin this down.  One, the terms "Maneuver Setting" and "Maneuver Flaps" are used interchangeably when they have different meanings.  The second is the original flap setting of 8 degrees may have been changed to 50%.

It is a good puzzle to solve.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on August 30, 2014, 06:01:01 PM
The pilot manual also says you can use up to half flaps for a shorter takeoff run. This clearly indicates that half flaps is about 20 degrees not 8 degrees.

I wonder how the flap indicator pin was marked. The original cockpit gauge used before the maneuver setting was added was marked up, 1/4,1/2, 3/4, and down.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on August 30, 2014, 08:45:16 PM
The pilot manual also says you can use up to half flaps for a shorter takeoff run. This clearly indicates that half flaps is about 20 degrees not 8 degrees.

I wonder how the flap indicator pin was marked. The original cockpit gauge used before the maneuver setting was added was marked up, 1/4,1/2, 3/4, and down.

There is no question about 50% flaps being more than 8%.

Now I found a description on the term maneuvering flaps. The article said the quick acting Lockeed's fowler flaps of 3 seconds down and 4 seconds up were called maneuvering flaps. It appears Lockheed developed higher speed flap deployment for the P-38 and used the term maneuver flaps to describe them.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Murdr on August 30, 2014, 08:49:37 PM
 It's explicitly clear in TO-01-75F-1 that the maneuver position of the flap control lever will deploy the flaps 1/2 way.  In variants before there was a maneuver position, the pilot had to pull the lever to "OPEN", watch the flap indicator, and then push it to "CLOSED" when the gauge said it was at 1/2.  The addition of a maneuver position was merely a change in the hydraulics, to lessen the work load on the pilot.  This Tech Order manual covers F-4 through G variants, so it gives notes for both situations.

As far as the degrees of deflection, I have always taken what may be interpreted as a discrepancy to mean that the specific mechanics of the fowler flaps hydraulic throw range isn't linear with the degree of flap deflection.  You can see this in the diagram AKAK posted.  If you reference only the horizontal travel of the flap hinge point, the position marked "maneuver", is 1/2 way horizontally between "retracted" and "landing".
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Mongoose on August 30, 2014, 10:26:59 PM
  Once upon a time, someone posted a link to AAF Manual 51-127-1, which is the Pilot Training Manual for the P-38.  It is a scanned document, so I can't copy and paste excerpts.  A quick google search found it available for download here:

https://drive.google.com/folderview?id=0Bw4FNWq6qRgqV251amlrdkdFcHc&usp=sharing

It talks about flaps starting on page 50.  According to this manual, there are four positions for the flap control lever:  Up, closed, maneu (short for maneuver), and down.  The instructions state that you use the Up and Down position to raise or lower the flaps, and move the lever to the closed position when you have the flaps at the desired position.  You can pull the lever straight to the maneuver position to move the flaps to the 50% down position for maneuvering in combat, or to prep for landing.  It does not say how many degrees this is.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Murdr on August 30, 2014, 10:52:19 PM
 Once upon a time, someone posted a link to AAF Manual 51-127-1

You can find that and a number of other manuals linked from the respective AHWiki page.  They are hosted on the trainers site.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Murdr on August 31, 2014, 12:27:31 AM
I maintain that the assumption of a 1:1 ratio between the range of motion of the hydraulics (which is what the gauge indicates) and degree of flap deflection is the cause of confusion.  The deflection is a function of where the flap assembly is at in the guide system.  The hydraulics merely move the flaps along the guides.  Can anyone see a mechanical truth in this diagram that excludes 50% of the hydraulic throw also being 8 degrees?

(http://legendsintheirowntime.com/Content/1944/P38_Av_4408_DA_flaps_p128_W.png)
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on August 31, 2014, 09:32:35 AM
Murder, will look at drawing Monday when I have my bigger screen back.

From all we have found, it looks like P-38F15 was set at 8 degrees.  The G model was reset at 50%.  There is test report comparing the G model to the F model.  In the test report, it makes note the G out turns the F in one full 360 degree turn.  Unfortunatly, they did not note  the F model revision number used in the test.

My guess is the Lockheed team wanted the 8degrees but combat feedback wanted the 50% flaps..

We also know notch 1 in AH is modeled at 8 degrees.

Super good discussion.  Thanks for all input.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on August 31, 2014, 11:53:38 AM
There's nothing official showing an 8 degree maneuver setting for the P-38. It's an internet myth based on a mistake and propagated by all the sites that just copy other sites.

When the maneuver position was first added it was set at 50%.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Murdr on August 31, 2014, 08:06:16 PM
Page 26 With and without a "MANEUV" position on the control lever, the indicator shows flaps 1/2 way down http://trainers.hitechcreations.com/historical/P-38%20pilots%20TO-01-75F-1.pdf

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.

I ignored this mistake earlier, but this is not correct.  There is no tilt before sliding back.  The whole flap assembly is pushed aft on its guides and deflects based on its positions in the guide.

This diagram is wrong:
(http://www.kazoku.org/xp-38n/articles/p38fowler.gif)

Jeffrey Ethel describing it correctly http://youtu.be/Y3nddCJbcdI?t=14m27s (thanks to youtube I didn't have to dig out this DVD)

Here he talks about using the maneuver setting http://youtu.be/Y3nddCJbcdI?t=15m41s  Jeffrey talks about his dads experience and "1 notch" of flaps.  Keep in mind that there is only 1 lever position to automatically deploy flaps to 1/2.  Otherwise, you pull the handle to the down position, and push it to closed to stop the flaps when they are in the desired position.

Here you can watch flaps retract from 1/2 to none http://youtu.be/PHSH1ZGSWe0?t=8m34s

Here you can watch flaps extend past 1/2 to full http://youtu.be/PHSH1ZGSWe0?t=14m29s

From all we have found, it looks like P-38F15 was set at 8 degrees.  The G model was reset at 50%. 
That sites modern diagram is wrong, yet you seem to want to accept that, and ignore a bunch of primary sources.

Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on August 31, 2014, 10:23:25 PM

. . . That sites modern diagram is wrong, yet you seem to want to accept that, and ignore a bunch of primary sources.


No not at all just trying to pin this down all the way around.  I thought your post very informative. 

We have several sources(Albeit they may be traceable to a single source) that say the P-38F-15 had 8 degree "Maneuv" flap settings.  To add to that we have a test report noting the G model out turns the F model inside of one turn.  If we knew the F model in the test was in the series that had the new flap setting feature then we might could say the F-15 did have an 8 degree flap setting and the G and latter models had 50% settings.

Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on August 31, 2014, 10:33:03 PM
Randy what makes you think the F model used flaps turning against the G model using the maneuver setting?  You aren't going to increase your turn rate 33% simply by tweaking the flap setting. If the G made 180 degrees more in one turn then it's making 3 dps for every 2 dps the F makes. That means the F was turning with no flaps and the G was turning with 50% flaps.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Murdr on September 01, 2014, 01:44:36 AM
Quote
Airplanes with serial numbers higher than 42-12667 (which was the first of a block of 20 F5A-1-LO) and 43-2064 (which was first of a block of 121 F-15-LOs) are equipped with maneuvering flaps (Reference paragraph 11) which are 1/2 down when the flap control lever is set to "MANEUV" position.  On these planes it is not necessary to return the flap control lever to the "CLOSED" position to keep the flaps 1/2 down.
Section II, paragraph 9  
http://trainers.hitechcreations.com/historical/P-38%20pilots%20TO-01-75F-1.pdf

Straight out of TO-01-75-F with my notes in parenthesis on the production blocks started with those serials.  There is no basis for jumping to the conclusion that the "maneuver" flap setting was somehow different on the F variant than later variants.  In fact it very explicitly says above the Fs maneuver setting is 1/2 flaps.

And just for reference, "are equipped with maneuvering flaps" refers to the addition of a control lever position.  Read before the quote and you'll find that pilots are instructed to manually stop extension at 1/2 to achieve the same result.

Another assertion that I have yet to see a basis for, is that 1/2 extension does not also happen to equal 8 degree deflection.  The only reason I'm not inclined to agree with FLS that it's simply a mistake is that I've went through so many primary references over the last 18 years, that I believe I'd have noticed it.  After all I did find and report to Pyro that the AH P-38G empty weight was off by a few hundred pounds, and various other data points in different planes that needed a minor tweak to match historical documentation.
 
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on September 01, 2014, 03:41:38 AM
I think the 50% angle is around 20 degrees relative to the underside of the wing because I think that matches the aerodynamic qualities described for the maneuver setting. It was max lift. The advice was don't use more than 50% until you're committed to landing. There was no "4th" notch of flaps if we consider maneuver to be the 3rd notch in AH. The advice to pilots was to use maneuver until you went to full down even though they had the ability to stop the flaps on the "4th" notch.

The 8 degree flap extension is a minimum drag extension but it's also not a max lift extension. I'm assuming the full range is 40 degrees based on visuals and the modeling blueprint. The desirable 8 degree position would be available by manual selection using the indicator pin in the wing as a guide. I'd like to see how that's marked, but I'm guessing it shows something besides half and full. Zeno's P-38 video only shows the old style gauge used prior to the maneuver flap upgrade.

If you cut yourself an 8 degree wedge, a 20 and a 40, then use them to assess P-38 flap positions, I think you'll find 20 degrees more likely for half extended.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on September 01, 2014, 05:54:10 AM
It could be too the 8 degrees was a typo and should have been 18 degrees.  I know y'all thought I was arguing for 8 degrees but I am not.  Just trying to find the bottom line to the maneuver setting and vet out the 8 degrees of which we have.

Again, thanks for all the replies.  I enjoyed reading all the information posted.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Murdr on September 01, 2014, 06:14:14 AM
I think the 50% angle is around 20 degrees relative to the underside of the wing because I think that matches the aerodynamic qualities described for the maneuver setting. It was max lift. The advice was don't use more than 50% until you're committed to landing. There was no "4th" notch of flaps if we consider maneuver to be the 3rd notch in AH. The advice to pilots was to use maneuver until you went to full down even though they had the ability to stop the flaps on the "4th" notch.

The 8 degree flap extension is a minimum drag extension but it's also not a max lift extension. I'm assuming the full range is 40 degrees based on visuals and the modeling blueprint. The desirable 8 degree position would be available by manual selection using the indicator pin in the wing as a guide. I'd like to see how that's marked, but I'm guessing it shows something besides half and full. Zeno's P-38 video only shows the old style gauge used prior to the maneuver flap upgrade.

If you cut yourself an 8 degree wedge, a 20 and a 40, then use them to assess P-38 flap positions, I think you'll find 20 degrees more likely for half extended.

Full flap extension on the P-38 is 35 degrees as stated in T.O. 01-75FG-2.

In this image you can see the flaps extended 50% with the carriage and tracks visible.  Using the rib above the carriage bolt removal hole (c) as a reference, we can see that the flap carriage is 2 more ribs behind the hole....
(https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-xap1/v/t1.0-9/10660197_836367893040267_5029187447764333434_n.jpg?oh=2239babcf3964f4568551d4c79b4e12f&oe=547B2E6F&__gda__=1415910579_6be178fe65547354aa78809c266e22eb)

Now in this picture where a flap is removed for maintenence, we can see that 2 ribs behind the hole is only slightly past the BEND in the track.
(https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-xfp1/v/t1.0-9/1496659_836367896373600_2703411659817008511_n.jpg?oh=53e6fa5011767454b336d43e458b5229&oe=5468DDE0&__gda__=1416512123_7092a0298e3b10e430dd92b1e71e3229)
From the retracted position the flap moves aft over 1/4 of it's range adding wing area, but with minimal deflection.  When the upper flap carriage reaches the bend in the upper track it starts to deflect the flap.  The lower flap carriage reaches the end of the lower track, while the top continues to move rotating the flap rapidly during the second 1/2 of it's range of motion.

And here is what I've been saying all along, which is confirmed in T.O. 01-75FG-2.  The indicator is driven from a gear meshed with the drive screw.  The drive screw runs the cables that actually move the flaps.  The indicator only tells the pilot where the flaps are within it's range of motion fore and aft.  It does not directly indicate flap deflection like you'd expect from a split or plain flap.

Quote
Wing flaps are Lockheed-Fowler type which roll aft and down from the trailing edge on tracks beneath the wing, extending the actual area of the wing as well as increasing lift.  Relatively slow landings of highly wing-loaded aircraft are made possible because of the high lift coefficients.  With the flap in a partially extended position, a large increase in lift is provided with minimal increase in drag.  This makes possible for use of these flaps for take off as well as for a maneuvering flap in combat.  -Joseph Johnson YP-38 project engineer

Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Murdr on September 01, 2014, 06:28:42 AM
The advice to pilots was to use maneuver until you went to full down even though they had the ability to stop the flaps on the "4th" notch.
Just curious where you are getting this.  Everything I've ever read from Lockheed and USAAF says to use the maneuver setting as short as possible because of the loss of speed.  I've seen a number of accounts of (mainly PAC) pilots using more than the maneuver flaps, but that was discouraged in training.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Murdr on September 01, 2014, 07:42:29 AM
It could be too the 8 degrees was a typo and should have been 18 degrees.
The odd thing is that it's not just an internet typo that got copied to other sites.  It's in print in published books too.  But I've never came across a primary source of it that I can remember.   I'm not really set on X degrees has to be the answer, I'm just skeptical that 1/2 on the gauge has to be 50% of full deflection.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on September 01, 2014, 09:33:35 AM
Just curious where you are getting this.  Everything I've ever read from Lockheed and USAAF says to use the maneuver setting as short as possible because of the loss of speed.  I've seen a number of accounts of (mainly PAC) pilots using more than the maneuver flaps, but that was discouraged in training.

That's from the pilot manual landing instructions when you generally leave them down. The manual also says the dive flaps deploy to 35 degrees. Do the flaps and dive flaps use the same max angle? I haven't seen the flap deflection range in the manual.  I understand extension and deflection are different. I don't believe that half extended equals 8 degrees deflection, it just looks bigger. Look at Ack-ack's picture of 985.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on September 01, 2014, 01:10:54 PM
The odd thing is that it's not just an internet typo that got copied to other sites.  It's in print in published books too.  But I've never came across a primary source of it that I can remember.   I'm not really set on X degrees has to be the answer, I'm just skeptical that 1/2 on the gauge has to be 50% of full deflection.

It could be a typo in the original Lockheed logs of plane revisions.  Or it still could be the original Lockheed recommendation to make the setting 8 degrees but was quickly changed to the 50% setting.  The media article giving the time to maneuver setting of 3 seconds is also compelling.

Remember HighTek's post where he posted that don't put too much in the flap indicators as a reference.  He noted as an example that AH's first notch was modeled at 8 degrees which even adds more to the 8 degree mystery.  They modeled all flaps to the best information available best i can tell.

I wonder if this could guide us in a test to see which notch in AH is the maneuver setting.

From the P-38F and P-38G comparison test.
Quote
The P-38G turns much better than the P-38F (will close 180 in 360 circle) due to maneuver flaps.

Quote
At twenty-five-thousand (25,000) feet the P-38G stalled in a turn at an IAS of about 110 mph with maneuver flaps extended. The P-38F stalled at about 145 mph IAS.


Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Murdr on September 01, 2014, 01:11:51 PM
That's from the pilot manual landing instructions when you generally leave them down.
OK, it sounded like you were referring to them in the context of maneuvering.  When landing full flaps come out within a litteral few seconds of the wheels touching the ground, so yea, you just dump the lever because the flap hydraulics automatically cut off when the flaps reach the stops.
The manual also says the dive flaps deploy to 35 degrees. Do the flaps and dive flaps use the same max angle? I haven't seen the flap deflection range in the manual.
(https://fbcdn-sphotos-b-a.akamaihd.net/hphotos-ak-xap1/v/t1.0-9/10624887_836553179688405_2620421856177432737_n.jpg?oh=d3905f32ceb0df47d834016ec3506d33&oe=5470785C&__gda__=1417198464_3d9feef8f939214cfdbfca75dd6d30e5)

Hall Hibbard Lockheed Chief Engineer cited 40 degrees for the dive flaps
(http://legendsintheirowntime.com/Content/1944/P38_Av_4408_DA_flap_p127_W.png)
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Murdr on September 01, 2014, 01:16:59 PM
Remember HighTek's post where he posted that don't put too much in the flap indicators as a reference.  He noted as an example that AH's first notch was modeled at 8 degrees which even adds more to the 8 degree mystery.  They modeled all flaps to the best information available best i can tell.

Check out the old P-38 help page http://www.hitechcreations.com/ahhelp/models/p38l.html
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on September 01, 2014, 01:36:51 PM
Check out the old P-38 help page http://www.hitechcreations.com/ahhelp/models/p38l.html

Wow what a find.

I looked at my handy protractor to get a good idea of what 8 degrees is and it looks like the angled upper track may drop 8 degrees albeit a WAG.

Now, could 50% be travel on the track not angle?   Could it be then at 50% of the flaps travel the angle is 8 degrees?

As Murder pointed out the lower track stops letting the drop in the upper track push the flap into a steeper angle as it travels back.  The point at which the lower track stops and the flap turns down my give it an 8 degree drop and be 50% track travel.  And we know it happens in 3 seconds.

That would make the 8 degrees and 50% flap agree.

What do you think Murder and FLS?
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on September 01, 2014, 02:34:08 PM
Randy the track angle is different than the flap angle.

Murdr there's an article by Hall Hibbard where he states the dive flaps extend 40 degrees. The manual says 35 for dive flaps.
Since there are still P-38's it shouldn't be impossible to find the correct answer. In any case approximately 35 degrees for wing flaps is close enough to my assumption of 40 to maintain my belief that the maneuvering position is nearer 20 degrees than 8.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Murdr on September 01, 2014, 03:18:00 PM
Murdr there's an article by Hall Hibbard where he states the dive flaps extend 40 degrees. The manual says 35 for dive flaps.
Umm yea, that's where the image came from.  Just out of curiosity can you point out where the 35 degree reference is?
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Murdr on September 01, 2014, 03:37:04 PM
That would make the 8 degrees and 50% flap agree.

What do you think Murder and FLS?

It still doesn't explain away the photographic appearance of the flaps at 50%.  Some of that could be resolved by assuming the reference angle is the chord/thrust line as opposed to the aft underside foil.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on September 01, 2014, 03:43:40 PM
Umm yea, that's where the image came from.  Just out of curiosity can you point out where the 35 degree reference is?

POH AAF 51-127-1  Page 52  The illustration shows 35 degrees.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on September 02, 2014, 06:28:30 AM
Randy the track angle is different than the flap angle.  . . .


It is FLS at the moment the bottom slider hits its stop.

I found another fowler flap curve that shows the maximum wing cord extension vs travel angle occurs at about 8 degrees.  The extended wing cord of course improves lift.  Again most bang for the buck.

http://books.google.com/books?id=NG2_qiSjmMEC&pg=PA533&lpg=PA533&dq=flap+extension+definition&source=bl&ots=O72hwzKCIg&sig=C2y0r-riJPEZNLv00ymtbimMkGk&hl=en&sa=X&ei=R6IFVMmeHsGBygT124KACg&ved=0CF0Q6AEwBg#v=onepage&q=flap%20extension%20definition&f=true (http://books.google.com/books?id=NG2_qiSjmMEC&pg=PA533&lpg=PA533&dq=flap+extension+definition&source=bl&ots=O72hwzKCIg&sig=C2y0r-riJPEZNLv00ymtbimMkGk&hl=en&sa=X&ei=R6IFVMmeHsGBygT124KACg&ved=0CF0Q6AEwBg#v=onepage&q=flap%20extension%20definition&f=true)

I am really starting to believe the 50% is of flap extension not flap angle when talking about Fowler flaps.

If 50% extension is where the bottom track hits its stop then 50% and 8 degrees may be the same thing.

Interesting no matter how this comes out.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Randy1 on September 03, 2014, 04:05:53 PM
After a bit of comparing photos and drawings I came to the following conclusions.

From Murder's pictures  and drawing and AK-AK's links It looks to me like the back roller on the top guide is sitting right next to the beginning of the decline in the top track when full retraced.  When the flap starts to extend the back roller follows the down slope of the top rail pushing the back trailing edge of the flap down to clear the trailing edge of the wing pocket the flap sits in retracted.  Before the front roller starts down the track decline the flap angle is somewhat less than the slope of the track decline.  The further down the track slope the front roller goes, the closer the flap gets to the track slope.  When the front roller hits the upper track decline the flap angle is equal to the track down slope.  Once there the bottom track-stop stops the bottom holding rod and the rod 's attaching point to the flap becomes the pivot and the flap makes a large change in angle in a the final extension. 

From this one can see the angle change on the flap during extension is much smaller in the beginning than the end.  If 50% represents travel then by the pictures, 50% is just before the upper front roller hits the down slope of the upper track. 

I feel fairly confident that 50% travel and 8 degrees are the same thing.  I would say I am 75% confident.  That sure would explain why some very creditable sources are both right.  In AH from all our post and especially Murder's, the Maneuver setting is notch one.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: earl1937 on September 08, 2014, 06:58:21 AM
After a bit of comparing photos and drawings I came to the following conclusions.

From Murder's pictures  and drawing and AK-AK's links It looks to me like the back roller on the top guide is sitting right next to the beginning of the decline in the top track when full retraced.  When the flap starts to extend the back roller follows the down slope of the top rail pushing the back trailing edge of the flap down to clear the trailing edge of the wing pocket the flap sits in retracted.  Before the front roller starts down the track decline the flap angle is somewhat less than the slope of the track decline.  The further down the track slope the front roller goes, the closer the flap gets to the track slope.  When the front roller hits the upper track decline the flap angle is equal to the track down slope.  Once there the bottom track-stop stops the bottom holding rod and the rod 's attaching point to the flap becomes the pivot and the flap makes a large change in angle in a the final extension. 

From this one can see the angle change on the flap during extension is much smaller in the beginning than the end.  If 50% represents travel then by the pictures, 50% is just before the upper front roller hits the down slope of the upper track. 

I feel fairly confident that 50% travel and 8 degrees are the same thing.  I would say I am 75% confident.  That sure would explain why some very creditable sources are both right.  In AH from all our post and especially Murder's, the Maneuver setting is notch one.
:airplane: One thing is for sure, this has been an interesting thread, but I think it is now time to see what comments are made from this statement: maneuvering flaps are used for what purpose?
The question is, what advantage does the maneuvering flap setting give the pilot during combat maneuvers? To extend that question, which flight control on the aircraft does the maneuvering flaps assist? To extend that question a little further: At what angle of attack of the wing does the 38 have the best turn performance while maintaining maximum combat airspeed?
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: FLS on September 09, 2014, 01:49:57 AM
We don't have a gauge for AOA Earl. Maximum combat airspeed occurs flying straight so I'm not sure what turn performance you're asking about. We generally describe your best instantaneous turn and your best sustained turn.

The advantage of the maneuver flap is to lower your stall speed without the added drag of full flaps. You typically get more than half of the lift increase in the first half of flap extension and more than half of the drag in the second half of flap extension.
Title: Re: P-38 MANEUVER Flap 8 Degrees?
Post by: Dobs on September 12, 2016, 10:46:15 AM
Interesting read....and more interesting conclusion.

Here is test report from WWII aircraft performance.
ARMY AIR FORCES PROVING GROUND COMMAND
EGLIN FIELD, FLORIDA
SUPPLEMENTARY REPORT
ON
TACTICAL SUITABILITY OF THE P-38G TYPE AIRPLANE
AS COMPARED TO THE P-38F
3 May 1943

Conclusions

                 a.    All conclusions and recommendations applying to the P-38F, apply to the P-38G.

                 b.    Inasmuch as the general maneuverability of this aircraft is probably the lowest of any type of current fighter aircraft, and in view of the competition facing the P-38G in the European Theatre, all possible effort should be made to improve its rate of climb and high speed.

                 c.    The P-38G turns much better than the P-38F (will close 180 in 360 circle) due to maneuver flaps.

But the other half of the coin is stall speed in AHIII seems high...

From
PILOT'S FLIGHT OPERATING INSTRUCTIONS
FOR ARMY MODELS
P-38H Series, P-38J Series, P-38L-1 L-5 and F-5B AIRPLANES

15. STALLS.
a. With power OFF, the airplane stalls at the following
indicated airspeeds at the gross weight noted:
                                                                                            (RPM max, boost min)  (RPM min, boost min)
                                             15,000 Ib. 17,000 Ib. 19,000 Ib.   AHII 17K 38L               AHII 17K 38L
Flaps and landing gear UP        94 mph     100 mph    105 mph     110mph                          118ish
Flaps and landing gear DOWN  69 mph      74 mph     78 mph
b. As stalling speed is approached, the center section
stalls first with noticeable shaking of the airplane, however,
the ailerons remain effective.
c. In either "power-on" or "power-off" stalls with
flaps and landing gear up, the airplane "mushes" straight
forward in a well-controlled stall. With flaps and landing
gear down, there appears to be a slight tendency for
one wing to drop. There is, however, no tendency to
spin. Under these conditions, the nose drops slightly
and, as the speed increases, the wing will come up.

IN AHIII, the plane drops off to left clean stall....