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Here's a brief note by the late Elliot Dent, a P-38 ace who flew with the famous 49th Fighter Group. It

was copied and posted to a usenet newsgroup by his son-in-law, circa 1996. I copied and saved it at the

time....

Other than knowing how to handle an engine-out situation on take-off (the usual

VMC business), the Lockheed offered no trouble. A complex airplane? For its

day, yes. A dangerous airplane? Not at all.This P-38 debate is endless, but some things about the P-38 that made it such

an marvelous design haven't been brought up that probably should be:

To achieve high-speed capability, an airplane will have high wing-loading(gross weight to wing area) and low power loading (gross weight to horsepower).

The P-38 had very high wing loading (which provides other benefits, such as

when penetrating weather, etc.), higher than anything other than one-off

record-breaking and racing planes when it was introduced. And it also hadunusually low power loading; in fact it had the lowest power loading of any US

design (maybe any design) of WWII. Turbocharging ensured this power loading

would remain constant to very high altitudes.This meant the airplane would be fast. But high wing loading would normally

degrade turning, climb and ceiling. With such high wing-loading, the P-38

should have been a dog in all but top speed. It wasn't because of two otherfactors.

One is its aspect ratio (span to chord ratio; that is, the relationship of the

length of the wing to its width). Another, related, factor is its span loading(ratio of airplane weight to wingspan).

In turns or climbs, a plane's drag tends to increase and its speed to decrease.

A way to counter this is to increase the wingspan. For any given wing area,

increasing the span decreases the chord, providing a higher aspect ratio. Forstructural and other reasons, most WWII-era fighters had aspect ratios of 6 or

less. The P-38 had an amazing aspect ratio of 8, meaning that it could gain

the advantage of high wing loading for speed and still not lose inmaneuverability, climb or ceiling.

A large wingspan, however, generally degrades a plane's rate of roll because

the wing surface is so far out from the fuselage and center of gravity. Makingthe wing tips narrower by tapering the plan form does a lot to counter this.

Normal fighter configurations had a taper ratio of about 2 (the wing tip being

only about half as wide as the wing root). The P-38 had a taper ratio of 3.

So, you had an airplane that was fast yet a good climber, a good turner andgood roller.

But wait--there's more:

Power has to be converted to thrust thru a propeller. Big powerful enginesneed big propellers to handle that power, but the diameter of a prop is limited

by tip speed. So power has to be absorbed by adding blades or increasing their

width. But a prop working harder on a given volume of air has inherentaerodynamic inefficiencies requiring performance compromises. Bottom line

being that propeller inefficiency limits the value of engine power.

But because the P-38's power was in two "sections" (engines), each with its ownpropeller, it was able to use its power as efficiently as a much lower-powered

airplane operating at lower speeds. And the increased propeller disc area of

the two props ensured that the plane's power and thrust would be maximized

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throughout the maneuver range.

This thrust efficiency made for an airplane that leaped into the sky on

take-off and could accelerate in the air like a drag racer.

Pretty neat, huh?But wait--there's more:

Ordinary fighters of the day had a tail length ratio (number of times the wing

chord goes into the distance from the center of gravity to the tail surfaces)of between 2 and 2.5. This ratio might be compared to wheelbase on a car. A

shorter wheelbase makes for a choppier, less stable ride. The P-38's tail

length ratio was a whopping 4. This means it had excellent damping, or thetendency to slow the rate of departure from a trimmed position. This made it a

great plane for flying long distances in, with one finger on the wheel, or for

instrument flying, or as a steady gun platform or for dropping bombs.

The large tail length ratio required a smaller than normal tail surface areabecause of the increased arm at which the surface worked. This reduced drag

and made for a truly excellent flying airplane.

Not bad, huh?But wait--there's more:

The width of the horizontal tail surface was determined by the spacing of the

booms. The result was a very high aspect ratio for the tail plane. Theendplate effect of the two vertical fins and rudder surfaces on the end of the

booms produced an aerodynamic apparent aspect ratio that was even higher. This

had the effect of providing very rapid changes in force with small changes inthe aircraft's angle of attack. This great sensitivity, combined with superb

damping, meant that less trimming force was necessary for stability and that

there was a wide range of CG position or stability available without

degradation of flying characteristics.Like, wow, man!

But wait--there's more:

The high aspect ratio of the horizontal tail also produced narrow chordelevators, which in a turn meant light control forces for maneuver. Ditto for

the vertical tail surfaces and rudders. Net effect, the pilot could dance the

airplane all over the sky without breaking a sweat, while bellowing out thelatest tunes from "Oklahoma!" to drown out the curses in his headphones of any

other pilot in some lesser machine that he chose to sky-wrassle with.

Because the engines rotated in opposite directions, they produced a symmetrical

slip stream flow which eliminated the need the carry rudder displacement, thusreducing a source of drag. And there was no change in trim with changes in

speed, which was a pure blessing in maneuver combat, er, dogfight.

Then there is the Fowler flap system, which actually increases wing area,tricycle landing gear, centerline fire guns, plenty of internal fuel, a roomy

cockpit....

The P-38 also had an amazing degree of detail refinement compared to otherplanes. All its external surfaces were smooth with no disturbances from rivets

or lap joints, for example.

One negative was necessarily small ailerons because of the wing taper, meaninglarge aileron displacement would be necessary to initiate a roll. That meant

high aileron forces. That's why the control wheel was used, and why the later

models had aileron boost. Savvy pilots would blip the inside throttle when

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they wanted a smart roll ASAP. Less savvy pilots did lots of pushups. And

there was the cockpit heating and defrosting thing (by the way, it's just as

cold at 25,000 ft. in the tropics as in Europe), which did get solved about as

soon as it became apparent. Cooling was never as effectively solved.But, all in all, a pretty damned good flying machine.

As pilots of the day said, if Jesus came back as an airplane, he would be a

P-38...

Elliot Dent