McDonnell XP-67

https://en.wikipedia.org/wiki/McDonnell_XP-67

The McDonnell XP-67 "Bat" or "Moonbat" was a prototype for a twin-engine,
long-range, single-seat interceptor aircraft for the United States Army Air
Forces. Although the design was conceptually advanced, it was beset by numerous
problems and never approached its anticipated level of performance. The project
was cancelled after the sole completed prototype was destroyed by an engine
fire.

In 1940, the U.S. Army Air Corps issued Request for Proposal R-40C, requesting
designs for a high-speed, long-range, high-altitude interceptor intended to
destroy enemy bombers. The specifications were very bold, encouraging
manufacturers to produce radical aircraft that would outperform any existing
fighter in the world at the time. The aerospace parts manufacturer McDonnell
Aircraft, eager to begin manufacturing its own aircraft, responded to the
proposal with drawings and specifications of the proposed Model I, which would
be powered by an unusual geared drivetrain with a single Allison V-3420 engine
buried in the fuselage powering twin wing-mounted pusher propellers in the
wings. However, 22 other manufacturers also issued proposals to meet the Army's
request; the McDonnell proposal had relatively unimpressive anticipated
performance, and its odd drivetrain was unproven. The Model I fell in 21st place
when the 23 proposals were examined and scored. The proposals that were accepted
included the similarly ill-fated XP-54, XP-55, and XP-56. Despite the apparent
setback, Air Corps leaders were impressed by the nascent company's efforts, and
granted McDonnell a $3,000 contract to re-engineer the aircraft.

On 30 September 1941, the USAAF granted McDonnell a $1,508,596 contract, plus an
$86,315 fee, for two prototypes, a wind tunnel model, and associated engineering
data. The Model IIa was designated as the XP-67. The production aircraft was
intended to have a pressurized cockpit, a novel innovation at the time. A number
of armament configurations were considered including six .50 in (12.7 mm)
machine guns, four 20 mm (.79 in) cannon, and even a 75 mm (2.95 in) cannon
before the configuration of six 37 mm (1.46 in) M4 cannon was chosen. Power
would be provided by two Continental XIV-1430-1 inverted V-12 engines, fitted
with turbosuperchargers, and the engine exhaust gases would augment thrust.


Role
Interceptor

Manufacturer
McDonnell Aircraft

First flight
6 January 1944

Status
Cancelled on 13 September 1944

Primary user
United States Army Air Forces

Number built
1

Program cost
US$4,742,746

....By this time, it was becoming obvious that the XP-67 was hampered by a
serious lack of power. The engines were only delivering 1,060 hp (790 kW), well
short of their promised 1,350 hp (1,007 kW) rating.

Although McDonnell promised a very impressive 500 mph (805 km/h) top speed with
the new powerplants, the Army rejected the proposal, demanding more testing of
the existing design. As a result of wind tunnel tests, the tailplanes were
raised 12 in (31 cm) while the XP-67 waited for replacement engines.

On 6 September 1944, the starboard engine of the XP-67 caught fire during a test
flight, and test pilot E.E. Elliot executed an emergency landing at Lambert
Field in St. Louis, Missouri. He attempted to park the craft pointing into the
wind to blow the flames away from the airframe, but the starboard main landing
gear brakes failed, pivoting the XP-67 so the flames blew directly towards the
aft fuselage. Elliot escaped safely, but the blaze gutted the fuselage, engine,
nacelle and starboard wing; the aircraft was a total loss.

The destruction of the lone flying prototype dealt a serious blow to the entire
program because the second prototype was only 15% complete at the time. Army
leaders decided to reevaluate the XP-67, ultimately deciding on 13 September
that it offered no significant advantages over existing fighters already in
service. The project was canceled, the remains of the first prototype were
scrapped, and work was halted on the second prototype.

Specifications (XP-67)

General characteristics
Crew: one, pilot
Length: 44 ft 9¼ in (13.65 m)
Wingspan: 55 ft (16.76 m)
Height: 15 ft 9 in (4.80 m)
Wing area: 414 ft2 (38.50 m2)
Empty weight: 17,745 lb (8,049 kg)
Loaded weight: 22,114 lb (10,031 kg)
Max. takeoff weight: 25,400 lb (11,521 kg)
Powerplant: 2 × Continental XIV-1430-17/19 twelve cylinder inverted vee
liquid-cooled engine, 1,350 hp (1,007 kW) each

Performance
Maximum speed: 405 mph (352 knots, 650 km/h) at 25,000 ft (7,600 m)
Cruise speed: 270 mph (235 knots, 435 km/h)
Range: 2,385 mi (2,074 nmi, 3,837 km)
Service ceiling: 37,400 ft (11,400 m)
Rate of climb: 2,600 ft/min (12.7 m/s)
Wing loading: 53.4 lb/ft2 (260 kg/m2)
Power/mass: 0.06 hp/lb (0.09 kW/kg)

Armament

Guns: 6 × 37 mm (1.46 in) M4 cannons (never installed in prototype)





*