P-38E wing experimental wings and fuselage

[Scott Rose]

Anybody have any more info on this image?

[Mark Allen M]

From the 456th FIS website. "While the P-38 design was starting to prove itself in testing and combat, one underlying problem still existed. Compressibility was still a major obstacle in the performance of the P-38, and it led to many rumors and myth about the flight characteristics. One prototype P-38 was modified for dive testing. An older P-38 E was the aircraft used for this experimentation. The forward gondola section was moved forward by thirty inches, and the cockpit was move forward by thirty-six inches. The cockpit flight controls were the same, but there was room behind the pilot for a co-pilot/observer/test engineer. This modified P-38 E "Swordfish" first too flight on June 2, 1943 and was immediately put into extensive dive tests. The tests would have limited results, but this design led into another use for this type of P-38.

AAF training before Pearl Harbor was only designed to train between 12,000 - 13,000 pilots each year. After the attack, plans were changed and the numbers were increased significantly. However, the problem was that the government was unprepared for any armed conflicts, and pilots were being forced into the P-38 without adequate training. There were no twin-engine trainers available, but when the British balked at purchasing the Model 322 Lightning I fighters, they were employed as trainers. They were basically stripped down models of the P-38, but they were still rather advanced for the average trained pilot taking the controls for the first time. Johnson envisioned the P-38 Swordfish to be used to take pilot trainees along for demonstration flights with an experienced pilot at the controls. This would dispel many rumors and raise confidence in inexperienced pilots. Lockheed test pilot Jimmy Mattern was sent on tour with a Swordfish version of the P-38. He performed maneuvers that were normally feared by the recruits, such as rolling into a "dead" engine and many low-level aerobatics. After five months of training sessions, P-38 accident rates dropped from 6.5% to 1.5%. Mattern would receive the Civil Medal of Merit for his actions, which saved the lives of many recruits. Once again, the P-38 demonstrated its versatility and value to the Allied cause."

[quemerford]

Not sure the dive testing part is correct: those aerofoil sections look unlike anything you'd want if confronting the idea of compressibility. I wonder if they are more likely to be laminar flow and aimed at extending the P-38's capability/range/efficiency/fuel tankage/use?

[old iron]

What is the odd device behind the wing? Surely something to conduct an experiment, since the drag would be prohibitive (also, only on one wing). I think the compressability hypothesis makes sense.

[sandiego89]

And is that a slot mid-span on the port wing? If so with the slot and the ducting just outboard the port nacelle (nothing on the Starboard side), perhaps some type of "sucking" for laminar flow, or "blowing" for a blown wing?

[bdk]

And is that a slot mid-span on the port wing? If so with the slot and the ducting just outboard the port nacelle (nothing on the Starboard side), perhaps some type of "sucking" for laminar flow, or "blowing" for a blown wing?

I concur. It looks like a setup, possibly using compressed air (or suction) from the turbo, to enhance laminar flow. You can see all the ducting going into the test section adjacent to the fuselage. The apparatus behind the wing is a pressure rake. This measures how smooth the air is behind the airfoil section.

Air bleeds and suction have been experimented with for years as a means of maintaining laminar flow to reduce drag. First they would test in the wind tunnel, then on an airplane.

https://ntrs.nasa.gov/archive/nasa/casi ... 090354.pdf

And a Douglas B-18 was used in this report:

https://ntrs.nasa.gov/archive/nasa/casi ... 092750.pdf

[jdeters79]

What is the odd device behind the wing? Surely something to conduct an experiment, since the drag would be prohibitive (also, only on one wing). I think the compressability hypothesis makes sense.

Looks like a pressure rake. More typically seen in wind tunnels for quantifying wake rather than on an aircraft, but not unheard of.

[T J Johansen]

Later (Aug. 1954) sold to Hycon Aerial Surveys as N91300. They did upgrade the plane to a J standard as well as incorporating their unique style nose configuration. Used until 1959 before being ferried to Las Vegas and put on consignment with Alamo Airways. Sold in June 1962 (together with N5596V and N9957V) to Don May of Phoenix, AZ. He then proceeded to sell the 38 to Bob Kucera, but was killed along with passenger Jerry Petersen when N91300 crashed shortly after take- off on Oct. 24, 1962.

T J

[Scott Rose]

Later (Aug. 1954) sold to Hycon Aerial Surveys as N91300. They did upgrade the plane to a J standard as well as incorporating their unique style nose configuration. Used until 1959 before being ferried to Las Vegas and put on consignment with Alamo Airways. Sold in June 1962 (together with N5596V and N9957V) to Don May of Phoenix, AZ. He then proceeded to sell the 38 to Bob Kucera, but was killed along with passenger Jerry Petersen when N91300 crashed shortly after take- off on Oct. 24, 1962.

T J

Warbird Registry: 41-2048

[k5083]

Cool plane. I wouldn't be surprised if the longer pod reduced drag and made it faster, like the T-33 vs. the P-80.

What color do we assume the lightning flash and spinners were? Red?

I assume the thing on the right wing is just a cuff to provide some aerodynamic symmetry with the airfoil being tested on the left wing?

August

[Joe Scheil]

An extensive mod, and the first TP-38?

The serial number is strange, as its painted on like a 1944 aircraft, and while it is an RP-38E the non-standard serial is really interesting. According to Baugher; "2048 was retained by contractor as NX91300 for experiments. Modified with lengthened pilot gondola section and all controls moved 3 feet forward into new cockpit section, original cockpit becoming an observer's position. To RFC Mar 19, 1946. Later used as test aircraft for XF-90 program. 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. Crashed on takeoff from Phoenix, Arizona Oct 24, 1962"

Interestingly if you look for the picture on the web, you will find an original print in the Wright State University Labs file with the border clearly stating "Lock P-38 44-12048 (and in pencil) c/n 7371 with negative number 4848....it would be nice to have the P-51K with the "same" tail number sitting next to this one...