Lindbergh & P-38 Range Increase

[megan]

One oft mentioned Lindbergh contribution to the war effort was his visit to P-38 squadrons in the Pacific and teaching pilots techniques on how to fly the aircraft for range, so increasing their radius of action.

I've long wonder what techniques he taught, does anyone have any idea?

My interest was piqued today by reading a Kitty Hawk I flight manual which has the following,NOTES ON MIXTURE CONTROL

The engine ls fitted with a Bendix-Stromberg carburettor Instead of the usual two-position mixture control, as fitted to British engines. the mixture control has the following 4 main positions:

FULL RICH: In this position there is no automatic compensation for altitude and temperature

AUTOMATIC RICH: This is the position for the richest mixture which is automatically maintained by the compensating device.

AUTOMATIC LEAN: This is the normd position for weak mixture. The automatic device maintains the mixture at this setting also.

IDLE CUT OFF: For stopping the engine and while priming during engine starting operations.

Furthermore, the mixture strength can be progressively weakened by moving the lever from the AUTOMATIC HIGH position towards the IDLE CUT-OFF position, the weakening being effective also in the region beyond the AUTOMATIC LEAN position up to the point where the IDLE CUT-OFF operates (at the extreme end of the travel). At any point in this range the automatic compensating device is in operation.

Although placing the mixture control in the AUTOMATIC LEAN position gives a considerable reduction in fuel consumption, it is possible to obtain a consumption of about 5% lower by adjusting the mixture control as follows:

1. Obtain the desired engine cruising conditions

2. Change the airscrew control from AUTOMATIC to MANUAL. In this position the airscrew becomes effectively a fixed pitch airscrew

3. Set the mixture control to the position determined by weakening the mixture until a drop of 40 to 50 R.P.M. is indicated. The position may possibly be between AUTOMATIC LEAN and IDLE CUT OFF

4. Return the airscrew control to AUTOMATIC

If changes in altitude or cruising conditions are made, this setting should be checked by repeating the above operations.Since the P-38 had the same mixture and prop control set up I'm inclined to think perhaps this may be the technique he taught.

[Allan Lupton]

Not my period but I'd expect the use of turbo-supercharging, which the P38 had, to make a difference

[megan]

Had not considered the turbos Allan, and you make a good point. The turbos did not come into action until the final one third of throttle movement, so if you stayed below the point, where the waste gate began closing, and the turbos came on line, you would be OK. Max cruise boost setting was 30", with 54" being max take off.

[Fareastdriver]

It was because of these techniques taught by Lindbergh that P38s had the range to intercept and shoot down Isoroku Yamamoto's aircraft over Bougainville.

[Groundbeard]

It was because of these techniques taught by Lindbergh that P38s had the range to intercept and shoot down Isoroku Yamamoto's aircraft over Bougainville.
Plus an extra large centreline droptank...

[megan]

The P-38 carried their drop tanks between the fuselage and engine. For the mission against Yamamoto only 165 US gallon tanks were available at the squadron, so a supply of 330 gallon tanks were flown in from New Guinea. Each aircraft carried a 165 and a 330 tank. The 330 tank could be carried without any problems, and 2X330 could be carried if required. In this case it was just availability.

[sidtheesexist]

I think I picked this up somewhere along the line.....
The long held wisdom says that with constant speed/variable pitch prop/engine combos, you 'square em off' e.g. 2400 rpm/24'' Manifold pressure in the cruise.
I was taught that bout 15 yrs ago and I believe it had been the norm for many moons. I believe Lindbergh worked out that by upping the Manifold pressure and reducing the rpm( analagous to top gear on a bike but low rpm) such as 1800rpm and 28'' Manifold, he got a significant range improvement. All the engine bods reckoned that the engines would suffer serious damage - short or long term I couldn't say but I believe that Ls concept contributed directly to the Yamamoto interception.
Hope this helps and if I have remembered incorrectly and/or am talking cobblers, I apologise unreservedly :ok:

[DaveReidUK]

Plus an extra large centreline droptank...

I'd be fascinated to know how much ground clearance a centreline tank on a P-38 would have.

[megan]

sidtheesexist, the RAF were operating their Allison engined Mustangs at 1,100 RPM and 30" for the purpose of extending range, so a report dated 26 August 1943 says. So may have been part and parcel of what Lindbergh taught.

[ICT_SLB]

I gave my copy away but IIRC "The Wartime Journals of Charles A. Lindbergh" published in 1970 includes a lot of detail as to the missions he carried out & training he gave. A certain South American river has hardback copies from $1.69.

[Jhieminga]

I would expect it to be related to specific power settings as well, not just how to use the mixture control.

[A681001]

mentioning P-38 drop tanks reminded me of some pictures of the tanks being modified for medivac and also recon ops , would not be a nice place to be :ooh:
scroll down on this link and there are some images of them
https://au.pinterest.com/dleemac67/photos-ww2-p38/

[dirkdj]

Lowering RPM and increasing MP will help the efficiency of the engine, especially if run lean of peak.

[dduxbury310]

Just a small point, but Yamamoto was shot down on 18th April 1943, and our friend Lindbergh did not arrive in the combat area until July 1944, being attached to the 475th FG as a civilian technician and advisor. So no way did the conqueror of the Atlantic give advice to the 339th Squadron at Guadalcanal in time to have any impact on the fortunes of the Imperial Navy's commander. Many years ago (when I was still at high school) I read much of the Wartime Journals of Lindbergh, and a jolly good read it was too. Think I even read about his experiences with the 475th as well, but cannot recall much - that must have been in about 1968!
David D

[megan]

Turns out that Lindbergh's method was nothing particularly esoteric I've found. Apparently normal squadron practice was to fly at 2,200 to 2,400 RPM with mixture auto rich. Lindbergh introduced the practise of 1,600 RPM and auto lean.

2,300 RPM was the change over point for auto lean/auto rich operation according to the manual. Lean allowed a max of 34.5", rich 38" at 2,300. The manuals provide data for auto lean cruise, so wonder why the squadron didn't use it?

[Jhieminga]

Perhaps something to do with the old myths about using lower rpms? Long range flying is not something that is adressed specifically during basic training, and I don't think it was back then.

[TBM-Legend]

When I flew a B-25 across the Pacific to Australia in 1983 to extend our fuel we used 1400rpm and 29in of boost in auto lean.... these figures are in the AFM [landed in HNL with 60 galls!!!!]

*Every 30 minutes or so brought the rpm up to 1850 for 10 minutes to clear the plugs..

[Audiophile_AU]

Hi all,
the low revs high boost technique was known by Rolls Royce and demonstrated to RAF pilots on an engine run test rig they had. I think Ronnie Harker, who was one of RR's liaison technical people to the RAF squadrons, has mention of it in his book. And yes every 15 mins or so you had to rev up to clear the spark plugs.
regards
David