McDonnell XF-85 «Goblin» — South American jet aircraft, designed as a fighter escort, which could be based on a heavy bomber Convair B-36. The layout was not performed serially.
History McDonnell XF-85 «Goblin» tightly interwoven with the history of bomber Convair B-36. First thoughts on the development of strategic bombers that could start with the U.S. countryside, overcome tremendous distance to the enemy positions, and doing battle puzzle, to turn back, appeared in the U.S. military in 1941. Its development was delayed so that take part in the war, he did not have time. When the build machine with a radius of about 9000 km act was close to the end, it turned out that she did not quite fit into the adopted while introducing the concept of bombers: escort fighter was not capable for the flight to follow such a bomber. Ordinary aircraft — well, and those that could be designed to start with airfields coupled with Convair B-36 — not suitable: first — because obviously insufficient range, and the second would leave very heavy and therefore not perfectly able to repel the enemy interceptors. In addition, such a fighter pilot and is the entire flight in a constant voltage, is immensely sluggish to the point where there is a need to dogfight. Representatives of the U.S. Air Force believed that these difficulties can be solved only by using an unusual approach.
In December 1942, the U.S. Air Force announced a competition entitled «Project MX-472» — the long-distance bomber escort languid. Within 2 years a special commission made out a number of projects, but chose the project «parasite fighter», which was a huge part of the flight to the bombers inside the housing, and in case of need — produced outside. The decision was not entirely new — airships similar schemes existed for 20 years before the construction of Convair B-36.
The only company that submitted to the Commission very seriously researched airplane design such type was quite young company «McDonnell». Despite a number of problems have emerged, engineers running Herman Barkley, who worked to form the company «McDonnell» the firm «Curtiss», in the short term presented several projects that meet the requirements of the Air Force. Options were offered differing views of attachment: semi-recessed or internal suspension. By the beginning of 1945, the U.S. Air Force chose the project, which included an internal suspension, which had trade designation «Model 27D».
Strategic bomber Convair B-36, which was designed under the Goblin
In March 1947, from the U.S. Air Force received an order to develop a 2-prototypes, and August 23, 1948 took place the first solo flight. The aircraft was launched from bombers Boeing EB-29B. As a result, flight testing, it was found that turbulence around bomber creates serious difficulties with control. However, such minatyurny that the plane could not hold the speed and maneuverability of fighters with whom he would have to beat it led to the termination of the forthcoming development.
The plane was equipped turbojet engine Westinghouse J34-WE-7 with a thrust 1361 kg. From the motor to the outlet nozzle exhaust pipe length was 1.32 m; engine and tube were covered with fiberglass wool to reduce heat losses covered duralumin foil. In addition, the engine was blown outside air from vozduhopoglotitelya. TRD installed in the forward fuselage, to move forward the center of mass of the aircraft, thus increasing shoulder tail. At a face velocity of 250 km / h turbine engine avtorotirovala because scroll turbocharger when starting from an aircraft carrier is not required. Ignition was performed using akkuma Willard BB 206 / V.
XF-85 Goblin # 46-523
Fuel system prototype consisted of the 1st horseshoe-sealing fuel tank capacity of 435 liters, herpes engine. Such volume provides 20 minutes of operation of the motor at full power and 32 Minutka in cruise mode. Longest duration of the flight, which was achieved during the test was 1 hour 17 minutes. On production aircraft was supposed to install two more wing tank compartment from 113 liters. and 95-liter tank in the fairing. All tanks were filled with an inert gas system to prevent fire; in addition, the aircraft was provided carbon dioxide fire extinguishing system.
Design features include low-lying hyperfine aircraft swept wings folding complex design with 6.44 m Wing span was 37 ° sweep across the front edge; folding unit placed at the root of the wing.
Small circular section fuselage was all metal made of duralumin alloys. Fuselage length was 4.32, width 1.27 m and height 2.0 All equipment, weapons and fuel tanks installed inside it.
XF-85 layout tests on the trapeze.
Been reviewed several options for mounting to the XF-85 bomber carrier, including using a longish rope with a loop at the end, after the capture of which fighter simply drawn into the bomb bay. But because of slackness there was a risk of collision rope tightens fighter with a carrier. To minimize it, dock the device was designed as a trapezoid complex design outlet parasite fighter-carrier from the fuselage or the feed to it without risk of collision. Coupling device mounted on a fighter, is a retractable metal hook with a spring-loaded trigger guard; Disconnecting from the bombers carried turning hook. Drive cleaning was electronic. Suspension system based on devices used in 30-x’s airships-twins Acron and Macon.
In the fuselage had four lightweight gun «Colt-Browning» M2 12.7mm ammunition with 300 rounds each. Then guns planned change to 20-millimeter cannons «Ford Pontiac» M-39. Reloading weapons carried pneumatically air bleed from the compressor motor.
Cockpit volume was only 0.74 m Because such crowding pilot’s seat could not make a height adjustable, but it was possible to adjust the machine-gun sight and pedals. Work ceiling Convair B-36 was the first models as much as 13 km, because, despite the moderate cabin volume, were provided its heating, sealing and charging. In addition, in the present aircraft oxygen system and high pressure cylinder supplies oxygen for breathing pilot in case of emergency evacuation of the aircraft. System Rescue pilot is one of the first options ejection seat T-4E with reclining 33 °.
The dashboard was also moderate, and carried a minimum desired devices: automatic radio indicators and gyro, airspeed indicator, altimeter, accelerometer pointers turbocharger speed, turbine temperature, fuel gauge and fuel pressure gauge. There was also a pressure gauge in the cockpit. So while catapulting the flyer does not hurt your feet, the dashboard was jettisoned together with canopy. Of radio equipment in the serial «parasite fighter» had installed AN/APN-61 finder and VHF AN/ARC-5, antenna which was located in the upper left ending fiberglass keel.
The slope of the control system is not equipped with hydraulic actuators. Ailerons wings ordinary type, with adjustable trim tabs in flight and aerodynamic compensation. Pitch control, but have cooperated very peculiar — differentiated by differences 4 arranged crosswise control surfaces. At the base of the law of their differences lay the same principle as for airplanes with a V-shaped fins: when giving pens they deviated in one direction, and when pedaling — in reverse. In the control channel tail surfaces was set unique differentiating mechanism. Handlebars were also provided with a trimmer that can be adjusted in flight, it was especially important, because the alignment of the aircraft as the depopulation of the fuel tanks is very varied.
These properties correspond to modifications XF-85.
Data Source: Characteristics Summary.
Crew: 1 (pilot)
Length: 4.5 m
Wingspan: 6.4 m
Height: 2.53 m
with folded wings: 3.32 m
Wing Area: 9.34 m?
Empty weight: 1807 kg
Normal take-off weight: 2540 kg
Fuel capacity: 435 l
Powerplant: 1? THD Westighouse J34-WE-22
Link: 1? 13.3 kN (1361 kgf)
The highest speed: 1043 km / h
Cruising speed: 689 km / h
Flight duration: 77 minutes
Service ceiling: 14,249 m
Rate of climb: 63.5 m / s
Time to climb: 10,668 m for 5.1 min
Gunnery 4? 12.7 mm machine gun with 1200 rds.
In add-on Secret Weapons of WWII Battlefield 1942 game player can pilot the XF-85 «Goblin», but then admitted historically incorrect — Goblin designed not during the second world war, and after it. In addition, there is a structural error — in the game XF-85 are fixed landing gear with aerodynamic fairings (like a dive bomber Junkers Ju 87) and the plane starts to land. Interestingly, in the intro three XF-85 attacking German positions, depicted without the chassis.
[Edit] Notable facts
During its elliptical shape and small size Goblin was nicknamed «The Flying Egg.»
For the development of the aircraft has been spent 3.1 million U.S. dollars.
Until now, the Goblin is the smallest fighter in the history of aviation