Hughes XF-11

https://en.wikipedia.org/wiki/Hughes_XF-11

The Hughes XF-11 was a prototype military reconnaissance aircraft, designed and
flown by Howard Hughes and built by Hughes Aircraft for the United States Army
Air Forces. Although 100 F-11s were ordered in 1943, only two prototypes and a
mockup were completed. During the first XF-11 flight in 1946, Howard Hughes
crashed the aircraft in Beverly Hills, California. The production aircraft had
been canceled in May 1945, but the second prototype was completed and
successfully flown in 1947. The program was extremely controversial from the
beginning, leading the U.S. Senate to investigate the F-11 and the Hughes H-4
Hercules flying boat in 1947–1948.

While Hughes had designed its predecessors to be fighter variants, the F-11 was
intended to meet the same operational objective as the Republic XF-12 Rainbow.
Specifications called for a fast, long-range, high-altitude photographic
reconnaissance aircraft. A highly modified version of the earlier
private-venture Hughes D-2 project, in configuration the aircraft resembled the
World War II Lockheed P-38 Lightning, but was much larger and heavier. It was a
tricycle-gear, twin-engine, twin-boom all-metal monoplane with a pressurized
central crew nacelle, with a much larger span and much higher aspect ratio than
the P-38's wing.

The XF-11 used Pratt & Whitney R-4360-31 28-cylinder radial engines. Each engine
drove a pair of contra-rotating four-bladed, controllable-pitch propellers,
which can increase performance and stability, at the cost of increased
mechanical complexity. Due to constant problems with the contra-rotating
propulsion system, the second prototype had regular single four-bladed
propellers.

On the urgent recommendation of Colonel Elliott Roosevelt, who led a team
surveying several reconnaissance aircraft proposals in September 1943, General
Henry "Hap" Arnold, chief of the U.S. Army Air Forces, ordered 100 F-11s for
delivery beginning in 1944. In this, Arnold overrode the strenuous objections of
the USAAF Materiel Command, which held that Hughes did not have the industrial
capacity or proven track record to deliver on his promises. (Materiel Command
did succeed in mandating that the F-11 be made of aluminum, unlike its wooden
D-2 predecessor.) Arnold made the decision "much against my better judgment and
the advice of my staff" after consultations with the White House. The order for
100 F-11s was reduced at the end of the war to just three. Hughes delivered only
one, a static test model, the other two were either destroyed in a hangar fire
or in his crash.

Numerous difficulties of both a technical and managerial nature accompanied the
program from the beginning. From 1946-1948, the Senate subcommittee to
investigate the Defense Program, popularly known as the Truman Committee and
then the Brewster Committee, investigated the F-11 and H-4 programs, leading to
the famous Hughes-Roosevelt hearings in August 1947. The program cost the
federal government $22 million.


Role
Aerial reconnaissance

Manufacturer
Hughes Aircraft

Designer
Howard Hughes

First flight
7 July 1946

Status
Canceled

Primary user
United States Army Air Force

Number built
2

Developed from
Hughes D-2


Early history and Beverly Hills crash

The first prototype, tail number 44-70155, piloted by Hughes, crashed on 7 July
1946 while on its maiden flight from the Hughes Aircraft Co. factory airfield at
Culver City, California.

Hughes did not follow the agreed testing program and communications protocol,
and remained airborne almost twice as long as planned. An hour into the flight
(after onboard recording cameras had run out of film), a leak caused the
right-hand propeller controls to lose their effectiveness and the rear propeller
subsequently reversed its pitch, disrupting that engine's thrust, which caused
the aircraft to yaw hard to the right. The USAAF account said that, "It appeared
that loss of hydraulic fluid caused failure of the pitch change mechanism of
right rear propeller. Mr. Hughes maintained full power of right engine and
reduced that of left engine instead of trying to fly with right propeller
windmilling without power. It was Wright Field's understanding that the crash
was attributed to pilot error," yet Hughes successfully brought suit against
Hamilton Standard for the malfunctioning counter-rotating blades in the right
propeller.

Rather than feathering the propeller, Hughes performed improvised
troubleshooting (including raising and lowering the gear) during which he flew
away from his factory runway. Constantly losing altitude, he finally attempted
to reach the golf course of the Los Angeles Country Club, but about 300 yards
(270 m) short of the course, the aircraft suddenly lost altitude and clipped
three houses. The third house was destroyed by fire, and Hughes was nearly
killed. The crash is dramatized in the 2004 film The Aviator.

Later history

The second prototype was fitted with conventional propellers and flown by Hughes
on 5 April 1947, after he had recuperated from his injuries. Initially, the
USAAF had insisted that Hughes not be allowed to fly the aircraft, but after a
personal appeal to Generals Ira Eaker and Carl Spaatz, he was allowed to do so
against posting of $5 million in security.

This test flight was uneventful, and the aircraft proved stable and controllable
at high speed. It lacked low-speed stability, however, as the ailerons were
ineffective at low altitudes. When the US Army Air Forces (USAAF) evaluated it
against the XF-12, testing revealed the XF-11 was harder to fly and maintain,
and projected that it would to be twice as expensive to build. A small
production order of 98 for the Republic F-12 had been issued, but the USAAF soon
chose the RB-50 Superfortress, and Northrop F-15 Reporter instead, both of which
had similar long-range photo-reconnaissance capability and were available at a
much lower cost.

The Republic F-12 production order was canceled. When the United States Air
Force was created as a separate service in September 1947, the XF-11 was
redesignated the XR-11. The surviving XR-11 prototype arrived at Eglin Field,
Florida, in December 1948 from Wright Field, Ohio, to undergo operational
suitability testing through July 1949 but a production contract for 98 was
canceled. The airframe was transferred to Sheppard AFB, Texas, on 26 July 1949
for use as a ground maintenance trainer by the 3750th Technical Training Wing,
and was dropped from the USAF inventory in November 1949.

Specifications (XF-11)

General characteristics
Crew: 2, pilot and navigator/photographer
Length: 65 ft 3 in (19.9 m)
Wingspan: 101 ft 5 in (30.9 m)
Wing area: 983 sq ft (91.3 m2)
Empty weight: 37,100 lb (16,828 kg)
Gross weight: 47,500 lb (21,546 kg) (4,000 mi (3,500 nmi; 6,400 km) range)
Max takeoff weight: 58,315 lb (26,451 kg) (5,000 mi (4,300 nmi; 8,000 km) range)
Powerplant: 2 × Pratt & Whitney R-4360-31 Wasp Major 28-cyl. air-cooled radial
piston engines, 3,000 hp (2,200 kW) each
Propellers: 8-bladed Hamilton Standard Hydromatic contra-rotating propellers

Performance
Maximum speed: 450 mph (720 km/h, 390 kn) at 33,000 ft (10,000 m); 295 mph (256
kn; 475 km/h) at sea level
Service ceiling: 42,000 ft (13,000 m)
Rate of climb: 1,000 ft/min (5.1 m/s)
Time to altitude: 33,000 ft (10,000 m) in 17.4 minutes
Wing loading: 59.3 lb/sq ft (290 kg/m2) (5,000 mi (4,300 nmi; 8,000 km) range)




*