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96-555: The XF-85 was a response to a USAAF requirement for a fighter to be carried within the Northrop XB-35 and B-36, then under development. This was to address the limited range of existing interceptor aircraft compared to the greater range of new bomber designs. The XF-85 was a diminutive jet aircraft featuring a distinctive potato-shaped fuselage and a forked-tail stabilizer design. The prototypes were built and underwent testing and evaluation in 1948. Flight tests showed promise in

192-402: A fixed-wing aircraft . "Anhedral angle" is the name given to negative dihedral angle, that is, when there is a downward angle from horizontal of the wings or tailplane of a fixed-wing aircraft. Dihedral angle has a strong influence on dihedral effect , which is named after it. Dihedral effect is the amount of roll moment produced in proportion to the amount of sideslip . Dihedral effect

288-523: A 35° swept wing and delta wing. McDonnell also considered adding a telescoping extension to the docking trapeze that would extend the device below the turbulent air under the mother ship. Before any further work on the trapeze, other modifications to the XF-85, or continued design studies on its follow-up could be carried out, the USAF canceled the XF-85 program on 24 October 1949. Two main reasons contributed to

384-454: A 648 mph (1,043 km/h) top speed proved optimistic. The first test flights revealed that turbulence during approach to the B-29 was significant, leading to the addition of upper and lower fins at the extreme rear fuselage, as well as two wingtip fins to compensate for the increased directional instability in docking. All the initial flights had the hook secured in a fixed position, but when

480-473: A YB-49 all-jet airframe crashed after Air Force test pilot Forbes pulled the outer wing panels off during stall tests at 4.8  g 0 (47  m/s ). The first YB-35 airframe jet-modified to a YB-49 completed all stall tests and even demonstrated recovery from a spin. It was later destroyed after the Flying Wing's forward landing gear strut and wheel collapsed after encountering high vibration during

576-408: A bomb bay. The diminutive aircraft measured 14 ft 10 in (4.52 m) long; the folding wings spanned 21 ft (6.4 m). Only a limited fuel supply of 112 US gal (93 imp gal; 420 L) was deemed necessary for the specified 30-minute combat endurance. A hook was installed along the aircraft's center of gravity; in flight, it retracted to lie flat in the upper part of

672-500: A bomb load. On 9 October 1945, the USAAF signed a letter of intent covering the engineering development for two prototypes ( US serial numbers 46-523/4 ), although the contract was not finalized until February 1947. After the successful conclusion of two reviews of a wooden mock-up in 1946 and 1947 by USAAF engineering staff, McDonnell constructed two prototypes in late 1947. The Model 27D was re-designated XP-85, but by June 1948, it

768-484: A bomber that could carry 4,500 kg (10,000 lb) of bombs to a round-trip mission of 16,000 km (10,000 mi). Requested performance was a maximum speed of 720 km/h (450 mph), cruise speed of 443 km/h (275 mph), and service ceiling of 14,000 m (45,000 ft). This aircraft would be able to bomb Nazi-occupied Europe in the event that Britain fell (this was similar to Nazi Germany's own Amerikabomber program design competition through

864-675: A confusion of rank and job changes, eventually cancelled the XB-35 project, while continuing testing the B-35 airframe as the YB-49, even ordering 30 of the jet-powered bombers after the first YB-49 crashed. The first and second XB-35s were scrapped on 23 and 19 August 1949, respectively. On 30 September 1943, 13 pre-production YB-35s were ordered by the Army Air Force. The first one did not fly until 15 May 1948. While some Air Force generals felt

960-512: A disturbance causes an aircraft to roll away from its normal wings-level position as in Figure 1, the aircraft will begin to move somewhat sideways toward the lower wing. In Figure 2, the airplane's flight path has started to move toward its left while the nose of the airplane is still pointing in the original direction. This means that the oncoming air is arriving somewhat from the left of the nose. The airplane now has sideslip angle in addition to

1056-496: A greater or lesser degree. Wing sweepback also increases the dihedral effect, for roughly 1° of effective dihedral with every 10° of sweepback. This is one reason for anhedral configuration on aircraft with high sweep angle, as well as on some airliners, even on low-wing aircraft such as the Tu-134 and Tu-154 . In any case, wing sweepback can also occur with a dihedral configuration. For instance, two small biplanes produced from

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1152-525: A height of 20,000 ft (6,000 m), he completed a 10-minute proving flight at speeds between 180 and 250 mph (290–400 km/h), testing controls and maneuverability. When he attempted a hook-up, it became obvious the Goblin was extremely sensitive to the bomber's turbulence , as well as being affected by the air cushion created by the two aircraft operating in close proximity. Constant but gentle adjustments of throttle and trim were necessary to overcome

1248-523: A height of 40 ft (12 m), causing substantial damage to the forward fuselage, air intake, and lower fuselage. The second prototype had to be substituted for the remainder of the wind tunnel tests and the initial flight tests. As a production series B-36 was unavailable, all XF-85 flight tests were carried out using a converted EB-29B Superfortress mother ship that had a modified, "cutaway" bomb bay complete with trapeze, front airflow deflector, and an array of camera equipment and instrumentation. Since

1344-492: A highly unusual taxi test procedure made with the engine's fuel tanks full, causing a fire that spread rapidly. Seven incomplete airframes began conversion to jet power as YB-49B but were never finished. A third YB-35 airframe was converted to use six jet engines (two placed in under wing pods) for use as a long-range reconnaissance aircraft, designated YRB-49A . After only a few months, the Air Force's order for 30 YRB-49As

1440-515: A means of reducing parasitic drag and eliminating structural weight not directly responsible for producing lift. Consolidated Vultee proposed a more conventional design with fuselage and tail, which was much larger and heavier. In theory, the B-35 could carry a greater payload faster, farther, and cheaper than a conventional bomber. In December 1941, the Army Air Forces awarded prototype contracts to both Northrop and Consolidated Vultee for

1536-473: A number of different options including the use of remotely piloted vehicles before choosing parasite fighters as the most viable B-36 defense. The concept of a parasite fighter had its origins in 1918, when the Royal Air Force examined the viability of Sopwith Camel parasite fighters operating from their 23-class airships . In the 1930s, the U.S. Navy had a short-lived operational parasite fighter,

1632-545: A second aircraft, which was exercised on 2 January 1942. The first was to be delivered in November 1943, the second in April of the next year. Detailed engineering began in early 1942. A fuselage-like crew cabin was to be embedded inside the wing; it included a tail cone protruding from the trailing edge. This tail cone would contain the remote sighting stations for the bomber's gunners and a cluster of rear-firing machine guns in

1728-494: A significant amount of engineering work in untested waters, the first order placed was actually for two prototypes of the XB-35, and included Northrop's plan to also build two all-wood one-third scale flying models to measure performance and stability; these were dubbed the Northrop N-9M (M standing for model). This aircraft would be used to gather flight test data on the Flying Wing design. Jack Northrop also hired part-time

1824-685: A total flight time of 2 hours and 19 minutes with only three of the free flights ending in a hookup. Schoch was the only pilot who ever flew the aircraft. Despite cancellation of the XF-85, the USAF continued to examine the concept of parasite aircraft as defensive fighters through a series of projects. These included Project MX-106 "Tip Tow", Project FICON, and Project "Tom-Tom"  – which involved fighter aircraft attached to bomber aircraft by their wingtips. Project FICON ("fighter conveyor") emerged as an effective Convair GRB-36D and Republic RF-84K Thunderflash combined bomber-reconnaissance-fighter, although

1920-404: Is a critical factor in the stability of an aircraft about the roll axis (the spiral mode ). It is also pertinent to the nature of an aircraft's Dutch roll oscillation and to maneuverability about the roll axis. Longitudinal dihedral is a comparatively obscure term related to the pitch axis of an airplane. It is the angle between the zero-lift axis of the wing and the zero-lift axis of

2016-478: Is caused by the center of lift and drag being further above the CG and having a longer moment arm. So, the same forces that change as sideslip changes (primarily sideforce, but also lift and drag) produce a larger moment about the CG of the aircraft. This is sometimes referred to as the pendulum effect . An extreme example of the effect of vertical CG on dihedral effect is a paraglider . The dihedral effect created by

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2112-437: Is less-ambiguously termed "spiral mode stability" and dihedral effect is a contributing factor to it. The dihedral angle contributes to the total dihedral effect of the aircraft. In turn, the dihedral effect contributes to stability of the spiral mode . A stable spiral mode will cause the aircraft to eventually return to a nominally "wings level" bank angle when the angle of the wings is disturbed to become off-level. If

2208-451: Is needed to get the amount of dihedral effect needed. Dihedral effect is defined simply to be the rolling moment caused by sideslip and nothing else. Rolling moments caused by other things that may be related to sideslip have different names. Dihedral effect is not caused by yaw rate , nor by the rate of sideslip change . Since dihedral effect is noticed by pilots when "rudder is applied", many pilots and other near-experts explain that

2304-427: Is the balance point of an aircraft. If suspended at this point and allowed to rotate, a body (aircraft) will be balanced. The front-to-back location of the CG is of primary importance for the general stability of the aircraft, but the vertical location has important effects as well. The vertical location of the CG changes the amount of dihedral effect. As the "vertical CG" moves lower, dihedral effect increases. This

2400-440: Is to contribute to stability in the roll axis. It is an important factor in the stability of the spiral mode which is sometimes called "roll stability". The dihedral effect does not contribute directly to the restoring of "wings level", but it indirectly helps restore "wings level" through its effect on the spiral mode of motion described below. Aircraft designers may increase dihedral angle to provide greater clearance between

2496-711: The Arado E.381 and Sombold So 344 were unrealized "paper projects". On 3 December 1942, the USAAF sent out a Request for Proposals (RfP) for a diminutive piston-engined fighter. By January 1944, the Air Technical Service Command refined the RfP and, in January ;1945, the specifications were further revised in MX-472 to specify a jet-powered aircraft. Although a number of aerospace companies studied

2592-576: The Beriev Be-12 were designed with gull wings bent near the root. Others, such as the Vought F4U Corsair , used an inverted gull wing design, which allowed for shorter landing struts and extra ground clearance for large propellers and external payloads, such as external fuel tanks or bombs. Modern polyhedral wing designs generally bend upwards near the wingtips (also known as tip dihedral ), increasing dihedral effect without increasing

2688-833: The Cernavodă bridge and Constantsa docks, in Romania . After that attack, the squadron, based in the Crimea, carried out a tactical attack on a bridge over the river Dnieper at Zaporozhye , which had been captured by advancing German troops. Later in World War II, the Luftwaffe experimented with the Messerschmitt Me 328 as a parasite fighter, but problems with its pulsejet engines could not be overcome. Other late-war rocket -powered parasite fighter projects such as

2784-671: The Curtiss F9C Sparrowhawk , aboard the airships Akron and Macon . Starting in 1931, aircraft designer Vladimir Vakhmistrov conducted experiments in the Soviet Union as part of the Zveno project during which up to five fighters of various types were carried by Polikarpov TB-2 and Tupolev TB-3 bombers. In August 1941, these combinations flew the only combat missions ever undertaken by parasite fighters – TB-3s carrying Polikarpov I-16 SPB dive bombers attacked

2880-573: The Northrop Corporation for the United States Army Air Forces during and shortly after World War II . The airplane used the radical and potentially very efficient flying wing design, in which the tail section and fuselage are eliminated and all payload is carried in a thick wing. Only prototypes and pre-production aircraft were built, although interest remained strong enough to warrant further development of

2976-529: The RLM , itself initiated in the spring of 1942). The original April 1941 USAAC proposal was first submitted to Boeing and Consolidated Aircraft Company and led to the production of the Convair B-36 . In May, one month before the USAAF was created, the contract was also extended to include Northrop, inviting it to submit a design along the lines it was already exploring. Since the new aircraft would require

McDonnell XF-85 Goblin - Misplaced Pages Continue

3072-410: The angle of incidence of the wing root chord and angle of incidence of the horizontal tail root chord. Longitudinal dihedral can also mean the angle between the zero-lift axis of the wing and the zero-lift axis of the horizontal tail instead of between the root chords of the two surfaces. This is the more meaningful usage because the directions of zero-lift are pertinent to trim and stability while

3168-422: The keel effect ) and so additional dihedral angle is often not required. Such designs can have excessive dihedral effect and so be excessively stable in the spiral mode, so anhedral angle on the wing is added to cancel out some of the dihedral effect so that the aircraft can be more easily maneuvered. Most aircraft have been designed with planar wings with simple dihedral (or anhedral). Some older aircraft such as

3264-411: The "leveling" direction more strongly, and less dihedral effect tries to roll the wings in the "leveling" direction less strongly. Dihedral effect helps stabilize the spiral mode by tending to roll the wings toward level in proportion to the amount of sideslip that builds up. It is not the whole picture however. At the same time that angle of sideslip is building up, the vertical fin is trying to turn

3360-594: The 1930s to 1945 by Bücker Flugzeugbau in Germany, the Bücker Jungmann two-seat trainer and the Bücker Jungmeister aerobatic competition biplane, were designed with sweepbacks of approximately 11 degrees, which provided significant dihedral effect – in addition to their small dihedral angles having a similar but lesser effect. The center of mass , usually called the center of gravity or "CG",

3456-462: The AAF which bought them at Wright Field without testing them or assuring reliability, and then shipped them to Northrop. Microfilmed records of reports and correspondence of the XB-35 program relate that after three or four flights, power plant and propeller vibrations increased, and the very efficient contra-rotating propellers began failing with frustrating frequency. Meetings were called by Northrop, of

3552-525: The AAF, Pratt & Whitney and Hamilton Standard where no one would take responsibility for correcting the AAF's engines and propellers. In addition, the AAF failed to supply the AC electrical alternator, insisting on Northrop using an onboard auxiliary power unit (APU) unit driven by an automotive engine which limited the high-altitude, high-speed XB-35 to test flights below 15,000 ft (4,600 m). The AAF also refused to allow Northrop proposed modification of

3648-646: The Convair B-36 needed more development money. At that time, it appeared the B-36 program might be cancelled as well as the B-35. The USAF and the Texas Congressional delegation desired to have a production program for the large Fort Worth aircraft production factory, and Convair had much more effective lobbyists in Washington, DC. The Northrop Corporation was always a technological trailblazer, but

3744-473: The EB-29B, named Monstro , was smaller than the B-36, the XF-85 would be flight tested half-exposed. To load the XF-85 into the host plane, a special "loading pit" was dug into the tarmac at South Base, Muroc Field , where all the flight tests originated. On 23 July 1948, the XF-85 flew the first of five captive flights, designed to test whether the EB-29B and its parasite fighter could fly "mated". The XF-85

3840-408: The Goblin to the bomber's trapeze, aborting four attempts before hitting the trapeze bar and breaking the hook on the XF-85's nose. Another forced landing was carried out at Muroc. With the first prototype's repairs completed, it also joined the flight test program, completing captive flights. While in flight, the Goblin was stable, easy to fly, and recoverable from spins, although initial estimates of

3936-628: The Northrop "all-wing" designs. There are long-standing conspiracy theories about the cancellation of the Flying Wing program; specifically, an accusation from Jack Northrop that Secretary of the Air Force Stuart Symington attempted to coerce him to merge his company with the Atlas Corporation-controlled Convair . In a 1979 taped interview, Jack Northrop claimed the Flying Wing contract

McDonnell XF-85 Goblin - Misplaced Pages Continue

4032-414: The XB-35 itself began in earnest. Unlike conventional aircraft, truly "tailless" flying wings do not have a rudder for lateral control, so a set of clamshell-like, double split flaps (so-called flaperon , a portmanteau of flap and aileron) on the trailing edge of the wingtips were used. When aileron control was input, they were deflected up or down as a single unit, just like an aileron. When rudder input

4128-524: The XB-35s until the government fixed their propulsion system. Concurrently, the AAF ordered Northrop to convert two of the YB-35 airframes to YB-49s, essentially substituting eight jet engines for four reciprocating engines. As a result, the airframe promptly flew to more than 40,000 ft (12,000 m) and topped 520 mph (840 km/h) in flight tests, verifying the XB-35 air frame's aerodynamics, but at

4224-544: The aircraft's center line, four above and below the outer wings, and four in the "stinger" tail cone. The B-35 would take advantage of a new aluminum alloy devised by Alcoa ; it was considerably stronger than any alloy used previously. In June 1946, the XB-35 made its first flight, a 45-minute trip from Hawthorne, California , to Muroc Dry Lake, without incident. The XB-35's engines and propellers were AAF property and had not been tested for engine-propeller compatibility by either Pratt & Whitney, Hamilton Standard, or by

4320-405: The angle between two paired surfaces, one on each side of the aircraft . Even then, it is almost always between the left and right wings . However, mathematically dihedral means the angle between any two planes. So, in aeronautics, in one case, the term "dihedral" is applied to mean the difference in angles between two front-to-back surfaces: Longitudinal dihedral is the difference between

4416-412: The angle the wings meet at the root, which may be restricted to meet other design criteria. Polyhedral is seen on gliders and some other aircraft. The McDonnell Douglas F-4 Phantom II is one such example, unique among jet fighters for having dihedral wingtips. This was added after flight testing of the flat winged prototype showed the need to correct some unanticipated spiral mode instability – angling

4512-416: The bank angle. Figure 2 shows the airplane as it presents itself to the oncoming air. In Figure 2, the sideslip conditions produce greater angle of attack on the forward-yawed wing and smaller angle of attack on the rearward-yawed wing. This alteration of angle of attack by sideslip is visible in Figure 2. As greater angle of attack produces more lift (in the usual case, when the wing is not near stalling),

4608-577: The bomb bays to carry the standard Mk. 3 atomic bomb, while at the same time declaring the AF would not buy the bomber unless it could carry the A-bomb. Northrop reluctantly agreed to try a single-rotation propeller, which slightly increased takeoff distance and a reduced rate-of-climb and maximum speed. Problems with the quartet of contra-rotating propellers ' shafts comprising each aircraft's drive-line system continued until finally Jack Northrop himself grounded

4704-444: The cancellation. The XF-85's deficiencies revealed in flight testing included a lackluster performance in relation to contemporary jet fighters, and the high demands on pilot skill experienced during docking revealed a critical shortcoming that was never fully corrected. The development of practical aerial refueling for conventional fighters used as bomber escort was also a factor in the cancellation. The two Goblins flew seven times, with

4800-629: The cancellation: MX-106 "Tip Tow" , FICON , and " Tom-Tom ." During World War II, American bombers such as the Boeing B-17 Flying Fortress , Consolidated B-24 Liberator , and Boeing B-29 Superfortress were protected by long-range escort fighters such as the Republic P-47 Thunderbolt and North American P-51 Mustang . These fighters could not match the range of the Northrop B-35 or Convair B-36,

4896-404: The competing propeller-driven B-36 was obsolete by that time and had just as many or even more development problems, the Air Force needed a very long-range, post-war atomic bomber to counter the perceived Soviet threat. It had more faith that the B-36's "teething" problems could be overcome, compared to those of the new and radical "Flying Wing", the unofficial name that was later associated with all

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4992-404: The composite bomber-fighter configuration. On 19 March 1945, McDonnell's design team led by Herman D. Barkey, submitted a revised proposal, the extensively redesigned Model 27D. The smaller aircraft had a potato-shaped fuselage, three fork-shaped vertical stabilizers, horizontal stabilizers with a significant dihedral , and 37° swept-back folding wings to allow it to fit in the confines of

5088-432: The cushioning effect. After three attempts to hook onto the trapeze, Schoch miscalculated his approach and struck the trapeze so violently that the canopy was smashed and ripped free and his helmet and mask were torn off. He saved the prototype by making a belly landing on the reinforced skid at the dry lake bed at Muroc . All flight testing was suspended for seven weeks while the XF-85 was repaired and modified. Schoch used

5184-451: The design as a jet bomber, under the designation YB-49 . The B-35 was the brainchild of Jack Northrop , who made the flying wing the focus of his work during the 1930s. In 1941 before the USA entered World War II, Northrop and Consolidated Vultee Corporation had been commissioned to develop a large wing-only, long-range bomber designated XB-35 and XB-36. Northrop advocated a "flying wing" as

5280-482: The design, but the aircraft's performance was inferior to the jet fighters it would have faced in combat, and there were difficulties in docking. The XF-85 was swiftly canceled, and the prototypes were thereafter relegated to museum exhibits. The 1947 successor to the USAAF, the United States Air Force (USAF), continued to examine the concept of parasite aircraft under three related projects following

5376-432: The dihedral angle on the horizontal tail. During design of a fixed-wing aircraft (or any aircraft with horizontal surfaces), changing dihedral angle is usually a relatively simple way to adjust the overall dihedral effect. This is to compensate for other design elements' influence on the dihedral effect. These other elements (such as wing sweep, vertical mount point of the wing, etc.) may be more difficult to change than

5472-438: The dihedral angle. As a result, differing amounts of dihedral angle can be found on different types of fixed-wing aircraft. For example, the dihedral angle is usually greater on low-wing aircraft than on otherwise-similar high-wing aircraft. This is because "highness" of a wing (or "lowness" of vertical center of gravity compared to the wing) naturally creates more dihedral effect itself. This makes it so less dihedral angle

5568-554: The dihedral effect. Dihedral effect of an aircraft is a rolling moment resulting from the vehicle having a non-zero angle of sideslip . Increasing the dihedral angle of an aircraft increases the dihedral effect on it. However, many other aircraft parameters also have a strong influence on dihedral effect. Some of these important factors are: wing sweep , vertical center of gravity , and the height and size of anything on an aircraft that changes its sidewards force as sideslip changes. Dihedral angle on an aircraft almost always implies

5664-401: The directions of the root chords are not. This measurement is also often referred to as decalage . In geometry, dihedral angle is the angle between two planes. Aviation usage differs slightly from usage in geometry. In aviation, the usage " di hedral" evolved to mean the positive, up angle between the left and right wings, while usage with the prefix "an-" (as in " an hedral") evolved to mean

5760-434: The down period to undertake a series of problem-free dummy dockings with a Lockheed P-80 Shooting Star fighter. After boosting the trim power by 50 percent, adjusting the aerodynamics, and other modifications, two further mated test flights were carried out before Schoch was able to make a successful release and hookup on 14 October 1948. During the fifth free flight on 22 October 1948, Schoch again found it difficult to hook

5856-436: The effectiveness of propeller control. After only 19 flights, Northrop grounded the first XB-35; the second aircraft was grounded after eight test flights. During this time, the contra-rotating propellers were removed and replaced with four-blade single-rotation propellers. In addition to having continued drive shaft vibration problems, the new single-rotation props greatly reduced the aircraft's speed and performance. Furthermore,

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5952-488: The feasibility of such aircraft, McDonnell was the only company to submit a proposal to the original 1942 request and later revised requirements. The company's Model 27 proposal was completely reworked to meet the new specifications. The initial concept for the Model 27 was for the fighter to be carried half-exposed under the B-29, B-35, or B-36. The USAAF rejected this proposal, citing increased drag, and hence reduced range for

6048-555: The first delivery date back to 1947. Seeing that it would almost certainly never be ready in time for the war, the Army Air Forces canceled the production contract, though the Air Technical Services Command continued to run the program for research purposes. Actual flight tests of the aircraft revealed several problems: the contra-rotating props caused constant heavy drive-shaft vibration and the government-supplied gearboxes had frequent malfunctions and reduced

6144-403: The forward wing will have more lift and the rearward wing will have less lift. This difference in lift between the wings is a rolling moment, and it is caused by the sideslip. It is a contribution to the total dihedral effect of the aircraft. The rolling moment created by the sideslip (labeled as "P") tends to roll the aircraft back to wings level. More dihedral effect tries to roll the wings in

6240-498: The hook was stowed and later raised, the resulting buffeting added to the difficulty in attempting a hookup. To address the problem, small aerodynamic fairings were added to the hook well that reduced the buffeting when the hook was extended and retracted. When testing resumed, on the 18 March 1949 test flight, Schoch continued to have difficulty in hooking up, striking and damaging the trapeze's nose-stabilizing section, before resorting to another emergency belly landing. After repairs to

6336-428: The horizontal tail. Longitudinal dihedral can influence the nature of controllability about the pitch axis and the nature of an aircraft's phugoid -mode oscillation. When the term "dihedral" (of an aircraft) is used by itself it is usually intended to mean "dihedral angle ". However, context may otherwise indicate that "dihedral effect " is the intended meaning. Dihedral angle is the upward angle from horizontal of

6432-400: The independent nature of Jack Northrop often collided with the political wheeling-and-dealing in Washington that tended to run huge military allocations. Consequently, the B-36 prevailed, with just over 380 aircraft built. Furthermore, earlier the same year, when the YB-49 jet bomber was cancelled, Northrop received a smaller production contract for its F-89 Scorpion fighter as compensation for

6528-530: The intricate exhaust system turned into a fiasco to maintain. After only two years of use, the engines already showed signs of metal fatigue . In the end, the program was terminated due to its technical difficulties and the obsolescence of its reciprocating propeller engines, and the fact it was far behind schedule and over budget. Another contributing factor to the program's failure was the tendency of Northrop to become engaged in many experimental programs, which spread its small engineering staff far too wide. While

6624-446: The leading aeronautical designer of the day Theodore von Kármán , to evaluate and who approved of Northrop's initial design, and to start building the tooling for building the prototypes ... as explained in detail in the book "Goodbye Beautiful Wing" by Terrence O'Neill ( ISBN   978-0979012129 ). The N9Ms would also be used as a flight trainer, to familiarize pilots with the radical, all-wing concept. Early in 1942, design work on

6720-402: The lost Flying Wing contract. Data from Northrop Flying Wings : a history of Jack Northrop's visionary aircraft General characteristics Performance Armament Related development Aircraft of comparable role, configuration, and era Related lists Dihedral (aircraft) Dihedral angle is the upward angle from horizontal of the wings or tailplane of

6816-563: The negative, down angle between the wings. The aerodynamic stabilizing qualities of a dihedral angle were described in an influential 1810 article by Sir George Cayley . In analysis of aircraft stability, the dihedral effect is also a stability derivative called C l β {\displaystyle \beta } meaning the change in rolling moment coefficient (the " C l ") per degree (or radian) of change in sideslip angle (the " β {\displaystyle \beta } "). The purpose of dihedral effect

6912-592: The next generation of bombers developed by the United States Army Air Forces (USAAF). The development cost for longer-ranged fighters was high, while aerial refueling was still considered risky and technologically difficult. Pilot fatigue had also been a problem during long fighter escort missions in Europe and the Pacific, giving further impetus to innovative approaches. The USAAF considered

7008-437: The nose back into the wind, much like a weathervane, minimizing the amount of sideslip that can be present. If there is no sideslip, there can be no restoring rolling moment. If there is less sideslip, there is less restoring rolling moment. Yaw stability created by the vertical fin opposes the tendency for dihedral effect to roll the wings back level by limiting sideslip. The spiral mode is the tendency to slowly diverge from, or

7104-415: The nose made up the aircraft's armament. In service, the parasite fighter would be launched and retrieved by a trapeze . With the trapeze fully extended, the engine would be airstarted and the release from the mother ship was accomplished by the pilot pulling the nose back to disengage from the hook. In recovery, the aircraft would approach the mother ship from underneath and link up with the trapeze using

7200-494: The nose. The aircraft had an empty weight just short of 4,000 pounds (1.8 t). To save weight, the fighter had no landing gear. During the testing program, a fixed steel skid under the fuselage and spring-steel "runners" at the underside of the wingtips were installed in case of an emergency landing. Despite the cramped quarters, the pilot was provided with a cordite ejection seat, bail-out oxygen bottle, and high-speed ribbon parachute. Four .50 in (12.7 mm) machine guns in

7296-403: The piston engines made the B-35 obsolete, it remained superior in overall performance and range to its competitor, the Convair B-36, and General Hoyt Vandenberg wrote that only the B-35 and the B-36 had adequate range for the Air Force's primary mission, and nothing comparable would be available until the mid-1950s. Only the first YB-35 was ever flown. Multiple flight testing demonstrated that it

7392-529: The price of range. The prop-version had a design range capable of reaching targets 4,000 mi (6,400 km) away, but the jet-engine version's range was cut nearly in half. The new version disqualified it for the Air Force's top-priority mission as a strategic bomber, which at that time meant striking at the USSR's industrial and military complexes in the Ural Mountains. The Air Force, itself involved in

7488-545: The production aircraft. In the midsection of the cabin, there were folding bunks for off-duty crew on long missions. The aircraft's bomb load was to be carried in six smaller bomb bays, three in each wing section, fitted with roll-away doors; this original design precluded the carrying of large bombs, and the early atomic bombs , without bomb bay redesign and modifications. Production aircraft would have defensive armament of twenty 0.5 in (12.7 mm) machine guns or 20 mm cannon, carried in six turrets, two turrets along

7584-602: The program's termination, the two XF-85 prototypes were stored, before being surplussed and relegated to museum display in 1950. Data from Experimental & Prototype U.S. Air Force Jet Fighters, McDonnell XF-85 Goblin : USAF Museum factsheet, McDonnell XF-85 : Boeing.com factsheet General characteristics Performance Armament Aircraft of comparable role, configuration, and era Related lists Northrop YB-35 The Northrop YB-35/XB-35 , Northrop designation N-9 or NS-9 , were experimental heavy bomber aircraft developed by

7680-484: The retractable hook in the aircraft's nose. The anticipated production shift would see a mixed B-36 fleet with both "fighter carriers" and bombers employed on missions. There were plans that, from the 24th B-36 onward, provisions would be made to accommodate one XF-85, with a maximum of four per bomber envisioned. Up to 10 percent of the B-36s on order were to be converted to fighter carriers with three or four F-85s instead of

7776-498: The role was changed to that of strategic reconnaissance. Project FICON drew heavily on data from the abortive XF-85 project and closely followed McDonnell's recommendations in designing a more refined trapeze. A total of 10 converted B-36s and 25 reconnaissance fighters saw limited service with the Strategic Air Command in 1955–1956, before they were supplemented by more effective aircraft and satellite systems. After

7872-443: The rolling moment is caused by one wing moving more quickly through the air and one wing less quickly. Indeed, these are actual effects, but they are not the dihedral effect, which is caused by being at a sideslip angle, not by getting to one. These other effects are called "rolling moment due to yaw rate" and "rolling moment due to sideslip rate" respectively. Dihedral effect is not roll stability in and of itself. Roll stability

7968-422: The stability of the spiral mode. This increases maneuverability which is desirable in fighter-type aircraft. Anhedral angles are also seen on aircraft with a high mounted wing, such as the very large Antonov An-124 and Lockheed C-5 Galaxy cargo aircraft. In such designs, the high mounted wing is above the aircraft's center of gravity which confers extra dihedral effect due to the pendulum effect (also called

8064-508: The tendency to slowly return to wings level. If the spiral mode is stable, the aircraft will slowly return to wings-level, if it is unstable, the aircraft will slowly diverge from wings-level. Dihedral effect and yaw stability are the two primary factors that affect the stability of the spiral mode, although there are other factors that affect it less strongly. Factors of design other than dihedral angle also contribute to dihedral effect. Each increases or decreases total aircraft dihedral effect to

8160-399: The trapeze, Schoch flew the first prototype on 8 April 1949, completing a 30-minute free flight test, but after three attempts, abandoned his efforts and resorted to another belly landing at Muroc. Aware of the problems revealed in flight tests, McDonnell reviewed the program and proposed a new development based on a more conventional design promising a Mach 0.9 capability, using alternatively

8256-762: The very low vertical CG more than compensates for the negative dihedral effect created by the strong anhedral of the necessarily strongly downward curving wing. The wing location on a fixed-wing aircraft will also influence its dihedral effect. A high-wing configuration provides about 5° of effective dihedral over a low-wing configuration. A side effect of too much dihedral effect, caused by excessive dihedral angle among other things, can be yaw-roll coupling (a tendency for an aircraft to Dutch roll ). This can be unpleasant to experience, or in extreme conditions it can lead to loss of control or can overstress an aircraft. Military fighter aircraft often have near zero or even anhedral angle reducing dihedral effect and hence reducing

8352-414: The wing tips and the runway. This is of particular concern with swept-wing aircraft, whose wingtips could hit the runway on rotation/touchdown. In military aircraft dihedral angle space may be used for mounting materiel and drop-tanks on wing hard points, especially in aircraft with low wings. The increased dihedral effect caused by this design choice may need to be compensated for, perhaps by decreasing

8448-417: The wings of a fixed-wing aircraft , or of any paired nominally-horizontal surfaces on any aircraft . The term can also apply to the wings of a bird . Dihedral angle is also used in some types of kites such as box kites. Wings with more than one angle change along the full span are said to be polyhedral . Dihedral angle has important stabilizing effects on flying bodies because it has a strong influence on

8544-644: Was a U.S. Navy designation for one YB-35 airframe to be used for development trials; the project was canceled while still in the planning stage. The U.S. Army Air Forces had originally ordered 200 production model B-35s. Since Northrop's facilities were not up to the task of producing them, the Glenn L. Martin Company agreed to undertake mass production. This proved irrelevant when the aircraft had too many development problems. Even disregarding these, so many of Martin's engineers had been drafted by 1944 that Martin pushed

8640-404: Was airworthy; it was then parked and ignored for more than a year until being scrapped on 20 July 1949. The unfinished YB-35 #2, was scrapped almost a month later, on 19 August 1949. The other 11 of 13 YB-35 aircraft ordered underwent conversion to other power plants. Two of those airframes were converted to use eight Allison J35 jet engines and designated YB-49 . The second YB-35 converted to

8736-414: Was cancelled because he would not agree to a merger because Convair's merger demands were "grossly unfair to Northrop." When Northrop refused, Symington supposedly arranged to cancel the B-35 and B-49 program. Symington became president of Convair after he left government service a short time later. Other observers note that the B-35 and B-49 designs had well-documented performance and design issues while

8832-471: Was carried in a stowed position, but was sometimes tethered and extended into the airstream with the engine off, for the pilot to gain some feel for the aircraft in flight. McDonnell test pilot Edwin Foresman Schoch was assigned to the project, riding in the XF-85 while it was stowed aboard the EB-29B, before attempting a "free" flight on 23 August 1948. After Schoch was released from the bomber at

8928-401: Was changed to XF-85 and given the name "Goblin". There were plans to acquire 30 production P-85s, but the USAAF took the cautious approach – if test results from the two prototypes were positive, production orders for more than 100 Goblins would be finalized later. During wind tunnel testing at Moffett Field , California, the first prototype XF-85 was accidentally dropped from a crane at

9024-414: Was made, the two surfaces on one side opened, top and bottom, creating drag, and yawing the aircraft. By applying input to both rudder pedals, both sets of surfaces were deployed creating drag so that the airspeed or the glide angle could be manipulated. On 22 November 1941, the United States Army Air Forces (USAAF, or AAF) signed the development contract for an XB-35; the contract included an option for

9120-416: Was suddenly cancelled without explanation. The sole YRB-49A built flew 13 test flights and then was returned to Northrop's Ontario Airport. The last of Northrop's big Flying Wings sat abandoned at the airport's edge for two years and was finally ordered scrapped on 1 December 1953. In order to test the advanced Northrop T37 Turbodyne turboprop engine, produced by a Northrop subsidiary, the ultimate YB-35A

9216-572: Was to be converted to a single EB-35B test aircraft (in this case the prefix "E" for the designation meant "Exempt," not the later Electronic). The test aircraft would use two of the powerful T37 engines, each driving a pair of contra-rotating, paddle-blade propellers; the first planned ground tests were to be made using a single T37 engine. When the EB-35B project was canceled, the Air Force had Northrop's Turbodyne engine name, all its patents, and technical data reassigned to General Electric . The XB2T-1

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