From: Joseph F Baugher <jfb@ihlpl.att.com>
Subject: Number Thirty-Eight in the Series--Lockheed P-38 Lightning (1 of 11)
Keywords: The Fork-Tailed Devil
Organization: AT&T Bell Laboratories -  Naperville, Illinois
Date: Mon, 16 Nov 1992 17:21:28 GMT


From Joseph F Baugher <jfb@ihlpl.att.com>

The Lockheed P-38 Lightning racked up an impressive series of 
"firsts"--it was the first Lockheed-designed military aircraft to go 
into series production, it was the first twin-engined interceptor to 
serve with the USAAC, it was the first production fighter powered by 
the Allison V-1710 in-line engine, it was the first modern fighter 
equipped with a tricycle landing gear, it was the first modern fighter 
to mount its guns ahead of the pilot where they can fire straight 
ahead, it was the first American plane to use butt-jointed flush 
riveted external surfaces, it was the first to make extensive use of 
stainless steel, it was the first fighter to use a bubble canopy right 
from the start, it was the first fighter with speeds over 400 mph, it 
was the first twin-boom fighter to go into production, it was the 
first USAAF fighter to shoot down a German aircraft, it was the first 
USAAF fighter to carry out an escort mission to Berlin, it was the 
first USAAF plane to land in Japan after that country had surrendered, 
it was the heaviest US fighter of World War 2, it was the only 
American fighter in production at the time of Pearl Harbor to be still 
in production at the war's end, and it accounted for more Japanese 
aircraft destroyed in combat than any other US fighter.  

Lockheed was invited along with Boeing, Consolidated, Curtiss, 
Douglas, and Vultee to take part in a USAAC design competition X-608 
for a twin-engined high-altitude interceptor.  The specification 
called for a maximum speed of at least 360 mph at 20,000 feet and 290 
mph at sea level, an endurance at full throttle of one hour at 20,000 
feet, and the ability to take off and land over a 50-foot obstacle 
within 2200 feet.  

The Lockheed design staff was headed by Hall L. Hibbard.  Working 
with Hibbard was the soon-to-be famous Clarence L. "Kelly" Johnson.  
After studying a lot of different designs, Hibbard and Johnson finally 
settled on a twin-boom design with each boom extending aft of the 
engine and the pilot sitting in an enclosed cockpit in a central 
nacelle.  Each boom was to house one of the new 1150 hp Allison 
V-1710C twelve-cylinder air-cooled engine with an exhaust-driven 
turbosupercharger.  The Allison engine at that time had just completed 
a 150-hour type approval test at 1000 hp.  The central nacelle 
contained a forward-firing armament of one cannon and four 0.50-in 
machine guns.  This armament was quite heavy for its time, the 
standard USAAC armament of the day being one 0.30-in and one 0.50-in 
machine guns.  One advantage of the twin-boom layout was the 
possibility of installing the armament in the central nacelle, 
unhampered by synchronizing gear and allowing sighting of the parallel 
streams of fire up to the maximum range of 1000 yards.  Tail surfaces 
consisted of a fin and rudder at the end of each boom and a horizontal 
tailplane and elevator between the booms.  It was anticipated that the 
twin fin-and-rudder tail assembly would increase the effective aspect 
ratio of the tailplane by the endplate effect, thereby providing 
stability over a large c.g. range.  At 14,800 pounds, the XP-38 
weighed more than a bombed-up Bristol Blenheim I, at that time the 
standard British medium bomber.  Fowler flaps were fitted between the 
ailerons and the booms and between the booms beneath the trailing edge 
of the wing center section.  

The project was given the company designation Model 22-64-01.  
Lockheed promised a maximum speed of over 400 mph.  Although the USAAC 
was somewhat skeptical about so radical a design, the Model 22 won 
Design Competition X-608 and on June 23, 1937, Lockheed was awarded a 
contract for one XP-38 prototype (Ser No 37-457).  Construction began 
in July 1938.  Construction proceeded rather rapidly despite the 
radical features that it embodied.  Few problems were presented by the 
installation of the Allison V-1710-11/15 (C9) engines, which developed 
960 hp at 10,000 feet and 1090 hp at 13,200 feet.  Each engine had a 
General Electric B-1 turbosupercharger.  To combat torque, the 
propellers rotated in opposite directions, a special version of the 
Allison engine being produced with a left-hand rotating propeller 
shaft.  The engines had inwardly-rotating propellers.  No armament was 
installed on the XP-38.  

The XP-38 aircraft was completed in December of 1938.  On the last day 
of the year, the completed XP-38 was stripped down, covered with 
canvas, and loaded onto three trucks.  In great secrecy, the convoy of 
trucks was escorted by police to March Field, near Riverside, 
California, where Air Corps Project Officer Lt. Benjamin S. Kelsey 
was to began the flight testing.  However, on the very first ground 
run, the wheel brakes failed and the XP-38 ended up in a ditch.  Lt.  
Kelsey finally took the XP-38 into the air for the first time on 
January 27, 1939.  The early test flights turned up some problems with 
the wheel brakes and with vibrations of the flaps, requiring that some 
modifications be made to the prototype.  Maximum speed was 413 mph at 
20,000 feet, and an altitude of 20,000 feet could be attained in 6.5 
minutes.  Service ceiling was 38,000 feet.  Empty weight was 11,507 
lbs, gross weight was 13,964 lbs, and maximum takeoff weight was 
15,416 lbs 

Reaction to the first few test flights was highly favorable.  In spite 
of the problems encountered on its first few flights, it was decided 
to attempt a record transcontinental flight before delivering the 
XP-38 to the Army at Wright Field.  At daybreak on February 11, 1939, 
Ben Kelsey left March Field destined for Mitchell Field, New York with 
refuelling stops at Amarillo, Texas and Wright Field, Ohio.  On the 
final leg of the flight, the XP-38 lost power as Kelsey was coming in 
for a landing at Mitchell Field and crashed on a golf course just 
short of the runway.  Fortunately, Lt.  Kelsey was unhurt, but the 
XP-38 was a total loss.  

In spite of the loss of the XP-38, the Lightning had shown its true 
potential.  On April 27, 1939 a Limited Procurement Order for thirteen 
YP-38 service test aircraft was issued.  Army serials were 39-689/701.  
The company designation for the planes was Model 122-62-02.  The YP-38 
was redesigned for production and had a pair of 1150 hp Allison 
V-1710-27/29 (F2) engines equipped with B-2 turbosuperchargers.  These 
engines were equipped with spur reduction gearing rather than the 
former epicyclic type of gearing.  This caused the engine's thrust 
line to be raised.  The propellers were outward-rotating rather than 
inward-rotating as on the XP-38 (that is, the port propeller turned 
counterclockwise when seen from the rear and the starboard propeller 
turned clockwise).  The chin-mounted lip intake under the propeller 
spinner was replaced by a pair of cooling intakes.  Enlarged coolant 
radiators were adopted on both sides of the tail booms.  Armament was 
revised to substitute two 0.30-in machine guns for two of the four 
0.50-in machine guns, and a 37-mm cannon was substituted for the 20-mm 
weapon.  At 14,348 lbs, the YP-38 was lighter than the overweight 
XP-38 due to structural redesign.  

The first YP-38 flew on September 16, 1940 with Marshall Headle at the 
controls.  In March 1940, the Army received its first YP-38 for 
service trials.  Production lagged seriously behind schedule, and all 
thirteen YP-38s had not been completed until June of 1941.  Maximum 
speed was 405 mph at 10,000 feet, and an altitude of 20,000 feet could 
be reached in six minutes.  Normal range was 650 miles.  Empty weight 
was 11,171 lbs, gross weight was 13,500 lbs, and maximum takeoff 
weight was 14,348 lbs.  

During trials, the YP-38s ran into a tail buffet problem.  This was 
initially falsely diagnosed as elevator flutter, and a set of external 
mass balances were added above and below the elevator.  This problem 
was later solved by adding large wing-root fillets 

Even before the YP-38s had been built and delivered, on September 20, 
1939 the Army placed an order for 66 P-38 fighters.  

Twenty-nine of these were delivered as P-38-LO (company Model 
222-62-02).  The P-38 had the same powerplants as the YP-38, but 
armament was changed to one 37-mm cannon and four 0.50-in machine 
guns.  Armor plate and bulletproof glass was added for pilot 
protection, and fluorescent instrument lighting was provided for night 
flying.  Serials were 40-644/761 and 40-763/773.  

P-38 Ser No 40-744 was later modified to study the effects on flight 
crews of asymmetric cockpit location.  The turbosuperchargers were 
taken off the modified airplane, and the unit in the port boom was 
replaced by a cockpit for a flight surgeon.  

A change order to the initial contract provided for the completion of 
one P-38-LO (Ser No 40-762) equipped with a pressurized cockpit.  This 
airplane was redesignated XP-38A.  In order to offset the extra weight 
of the pressurized cockpit, the 37-mm cannon was to be replaced by a 
20-mm unit, but no armament was actually fitted to XP-38A prototype.  
Manufacturer's trials were performed between May and December of 1942, 
and the XP-38A was accepted by the USAAF at the end of that year.  
Much of the information gained on the XP-38A project was later used in 
the XP-49 design.  

The designations P-38B and P-38C were reserved for two versions 
proposed by Lockheed in late 1939.  These never got past the initial 
design stage.  

Reports coming in from the air war in Europe lead to the remainder of 
the initial order for 66 P-38s being completed as P-38D-LO.  Serials 
were 40-774/809.  The P-38D differed from the P-38 in having a 
low-pressure oxygen system, self-sealing fuel tanks, a retractable 
landing light, and provision for flares.  A change in tailplane 
incidence, together with a redistribution of elevator mass balances, 
increased the mechanical advantage of the elevator control, resulting 
in the elimination of buffeting and facilitating dive recovery.  The 
P-38D featured a new low-pressure oxygen system, which supplanted the 
old high-pressure oxygen system of earlier versions.  This system 
became standard on all subsequent production models.  Normal fuel 
capacity remained 210 gallons, but maximum internal fuel was reduced 
from 410 to 300 gallons.  The P-38D had a maximum speed of 390 mph at 
25,000 feet.  An altitude of 20,000 feet could be reached in 8 
minutes.  Service ceiling was 39,000 feet.  The first P-38Ds began to 
reach USAAF units in August 1941.  

For a brief period, the USAAF considered naming the P-38 "Atlanta".  
However, the P-38D and subsequent versions were officially christened 
"Lightning" by the USAAF.  

Neither the P-38 nor the P-38D were considered combat-ready.  In 1942, 
the P-38 was redesignated RP-38 and the P-38D was redesignated RP-38D, 
the 'R' prefix meaning 'restricted to non-combat roles'.  They were 
used strictly as combat trainers.  

By the time of Pearl Harbor, there were only 69 P-38 and P-38D 
fighters on strength.  

Chronologically, the Lightning Mark I for the RAF was the next model 
produced.  In France, as early as the spring of 1939, the Comite du 
Materiel and the Etat Major had been taking a look at the P-38 as a 
possible substitute for the Breguet 700, Potez 671, and Sud-Est 
S.E.100 twin-engined fighters then under development.  In April 1940, 
the Anglo-French Purchasing Committee ordered 667 P-38 fighters.  The 
two versions were the Model 322-61-03 (or 322-F) for France and 
322-61-04 (or 322-B) for Britain.  These were to be powered by 
unsupercharged Allison V-1710-C15 engines rated at 1010 hp at 14,000 
feet.  These aircraft were to have both engines rotating in the 
right-handed sense.  The French version of the fighter was to have 
French (i.e. metric-calibrated) instruments, French-built radios and 
French-supplied armament, and were to have throttles which operated in 
the "French fashion", ie.  in the reverse direction from 
British/American throttles.  The selection of the unsupercharged 
version of the Allison engine was carefully arrived at by the 
Anglo-French Purchasing Committee in order to standardize on the same 
powerplant as was used by the Curtiss H-81A, the export version of the 
P-40 for the Armee de l'Air and the Royal Air Force.  In addition, the 
Committee wanted to optimize the aircraft for medium-altitude combat 
as was currently the dominant mode of aerial warfare in Europe, rather 
than the high-altitude role for which the P-38 had originally been 
designed.  Furthermore, the US government was not anxious to have 
turbosuperchargers exported to Europe at that stage of the war.  With 
these unsupercharged engines, guaranteed maximum speed was 400 mph at 
16,900 feet.  

After the fall of France in June of 1940, the entire contract for the 
Model 322s was taken over by Britain.  Shortly thereafter, the 
contract was amended to provide for the delivery of 143 Lightning Is 
(British military serials AE978/999 and AF100/220) with the 
originally-specified V-1710-15 unsupercharged engines, with the 
remaining 524 aircraft (serials AF221/AF744) to be delivered as 
Lightning IIs (Model 322-60-04) with turbosupercharged V-1710-F5L and 
-F5R engines with guaranteed top speeds of 415 mph at 20,000 feet.  

Because of its unturbosupercharged right-handed Allison engines, the 
Lightning I for the RAF was christened the "castrated P-38" by the 
factory.  It turned out that this nickname was apt.  The performance 
of this hybrid was quite poor, and the RAF refused any further 
deliveries of the Lightning I after receiving and testing only three 
examples.  

The remaining 140 Lightning Is of the British contract were completed 
by Lockheed and were taken over by the USA and designated P-322, P for 
pursuit and 322 for the Lockheed model designation.  They were sent to 
a special modification center in Dallas, Texas where they were adapted 
for US service, most of them being used as trainers and for various 
experimental roles.  They retained their original British serial 
numbers while in USAAF service.  Twenty of the P-322s retained their 
V-1710-C15 engines (USAAF designation V-1710-33) with unhanded 
propellers They were assigned to operational use in the critical days 
following Pearl Harbor.  The rest of the P-322s were fitted with 
handed engines (V-1710-27 and -29) but were not given 
turbosuperchargers.  They were used as operational trainers with 
reduced armament (two 0.50-in and two 0.30-inch machine guns, no 
cannon).  

Only one Lightning II (AF221) was completed.  It was taken over by the 
USAAF as P-38F-13-10, painted with US national markings, but retained 
its British serial number.  It was used by Lockheed for the testing of 
smoke- laying canisters on racks between the booms and the nacelle, 
and for the air-dropping of two torpedoes from the same racks.  
Twenty-eight other British-ordered aircraft were completed as 
P-38F-13-LO for the USAAF, 121 as P-38F-15-LO, 174 as P-38G-13-LO, and 
200 as P-38G-15-LO.  

The first major production version for the USAAF was the P-38E-LO 
series (company designation Model 222-62-09).  It differed from the 
D-version in having the 37-mm cannon with the 15-round magazine 
replaced by a 20-mm cannon with 150 rounds.  The P-38E had improved 
instrumentation and revised hydraulic and electrical systems.  It had 
a revised nose section with double the ammunition capacity of earlier 
versions.  An SCR-274N radio was installed.  In the middle of 1941, 
the Hamilton Standard Hydromatic propellers with hollow steel blades 
were replaced on the production line by Curtiss Electric propellers 
with dural blades.  The P-38E was powered by Allison V-1710-27/29 
turbosupercharged engines.  Maximum speed was 395 mph at 25,000 feet.  
An altitude of 20,000 feet could be reached in 8 minutes, and service 
ceiling was 39,000 feet.  Weights were 11,880 lbs empty, 14,424 lbs 
gross, and 15,482 lbs maximum takeoff.  Serials of the USAAF P-38Es 
were: 41-1983/2097, 41-2100/2120, 41-2172, 41-2219, and 41-2221/2292.  
A total of 210 P-38Es were built.  

Early in its life the P-38 earned a reputation as a pilot killer.  A 
terminal velocity dive in a P-38 was believed by many pilots to be a 
fatal maneuver.  It was possible in a high- speed dive to overstress 
the plane while trying to pull out, and a number of P-38s lost 
empennages while doing such maneuvers and crashed, usually with fatal 
results.  It was later determined that these problems were the result 
of the effects of compressibility.  Although it was later found that 
ALL aircraft had problems when they operated in these speed ranges, 
the P-38 was a pioneer in high-speed flight and thus got a bad 
reputation.  

The most obvious effect of high speeds was the onset of tail flutter, 
which was at first believed to be caused by turbulence from the wing.  
The eventual flutter correction worked out by "Kelley" Johnson 
involved a change of incidence of the entire empennage from -1 deg 15 
minutes to 0 degrees 0 minutes and the addition of new fillets at the 
fuselage-wing leading edge junction.  

The P-38E was still not yet considered combat-ready, and most P-38Es 
were redesignated RP-38Es while others were used for various tests.  
41-1983 was used to test several features which later ended up being 
used in the P-38J and P-38K versions.  Some P-38Es were modified by 
Lockheed to carry drop tanks as developed for the P-38F-1-LO and later 
versions.  

One modified P-38E deserves special note.  During the spring of 1942, 
the rapidity of the Japanese advance caught everyone by surprise, and 
the USAAF became concerned with being able to ship its aircraft to the 
far reaches of the Southwest Pacific area.  One idea to improve the 
ease at which P-38s could be ferried to combat units in the Pacific 
islands was to equip these fighters with twin floats under the center 
section.  The retractable wheeled undercarriage would be retained, and 
the floats would be removed before combat operations from forward air 
bases were undertaken.  However, the success of the scheme demanded 
that a way be found to keep the tailplane free from spray.  As an 
experiment, P-38E Ser No 41-1986 was fitted with lengthened tail 
booms, its fins and rudders were recontoured and its tailplane was 
raised nearly three feet above its normal position.  In addition, an 
engineer/observer's seat was installed aft of the cockpit in place of 
some of the radio equipment.  41-1986 was only flown as a landplane, 
the proposed twin floats never being fitted.  In the event, such 
floatplane conversions proved to be unnecessary, since by the end of 
1942 the US Navy was fully able to provide adequate shipping for 
aircraft and materiel sent to the Southwest Pacific.  

P-38E Ser No 41-2048 was converted in 1942 as a two-seater with an 
elongated central nacelle extending aft of the wing trailing edge.  
This aircraft was intended as a research vehicle to find ways of 
reducing drag.  It was the only P-38 to have have a full dual set of 
flight controls.  Later in the war, this experimental aircraft was 
fitted with enlarged laminar-flow wing sections just outboard of the 
engine booms, complete with slots and boundary layer control by means 
of exhaust bleed air.  

One P-38E (serial number unknown) was used in 1942 at Orlando to 
demonstrate the feasibility of towing a Waco CG-4A glider.  A proposal 
was made to modify Lightnings to tow "trains" of up to three of these 
troop-carrying gliders, but nothing ever came of this idea.  

Ninety-nine aircraft originally ordered as P-38Es were completed as 
F-4-1-LO (Model 222-62-13) unarmed photo reconnaissance aircraft.  
They were powered by 1150 hp V-1710-21-29 engines and carried four 
K-17 cameras in a modified nose.  In service, these aircraft carried a 
pair of 150/165 US gallon drop tanks.  Most were retained for training 
and their restricted use status was reflected in their redesignation 
as RF-4-1-LO.  Serial numbers of the F-4-1-LO aircraft were 
41-2121/2156, 41-2158/2171, 41-2173/2218, and 41-2220.  

Next: The P-38F.

References:


  Lockheed Aircraft Since 1913, Rene J. Francillon, Naval Institute 
  Press, 1987 

  The P-38J-M Lockheed Lightning, Profile Publications, Le Roy Weber 
  Profile Publications, Ltd, 1965.  

  War Planes of the Second World War, Fighters, Volume Four, William 
  Green, Doubleday, 1964.  

  Famous Fighters of the Second World War, William Green, Doubleday, 
  1967.  

  The American Fighter, Enzo Anguluci and Peter Bowers, Orion Books, 
  1987.  

  Wings of the Weird and Wonderful, Captain Eric Brown, Airlife, 1985.  

  United States Military Aircraft since 1909, Gordon Swanborough and 
  Peter M. Bowers, Smithsonian Institution Press, 1989.  

Joe Baugher       AT&T Bell Laboratories    2000 North Naperville Road 
		  Naperville, Illinois 60566-7033.   (708) 713-4548

Newsgroups: sci.military