P-38 MANEUVER Flap 8 Degrees?

[Randy1]

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.

[FLS]

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%.

[Murdr]

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:


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.

[Randy1]

. . . 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.

[FLS]

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.

[Murdr]

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.
 

[FLS]

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.

[Randy1]

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.

[Murdr]

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....


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.

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.

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

[Murdr]

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.

[Murdr]

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.

[FLS]

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.

[Randy1]

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.

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

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.

[Murdr]

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.

Hall Hibbard Lockheed Chief Engineer cited 40 degrees for the dive flaps

[Murdr]

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