maanantai 20. maaliskuuta 2017

Grumman YOV-10D

The North American Rockwell OV-10 Bronco is an American turboprop light attack and observation aircraft. It was developed in the 1960s as a special aircraft for counter-insurgency (COIN) combat, and one of its primary missions was as a forward air control (FAC) aircraft. It can carry up to three tons of external munitions, internal loads such as paratroopers or stretchers, and can loiter for three or more hours.

The OV-10 has a central nacelle containing pilots and cargo, and twin booms containing twin turboprop engines. The visually distinctive item of the aircraft is the combination of the twin booms, with the horizontal stabilizer that connects them.

The aircraft's design supports effective operations from forward bases. The OV-10 can perform short takeoffs and landings, including on aircraft carriers and large deck amphibious assault ships without using catapults or arresting wires. Further, the OV-10 was designed to take off and land on unimproved sites. Repairs can be made with ordinary tools. No ground equipment is required to start the engines. And, if necessary, the engines will operate on high-octane automobile fuel with only a slight loss of power.
North American Rockwell OV-10 Bronco on yhdysvaltalainen potkuriturbiinikäyttöinen sotilaslentokone. Kone kykenee tiedustelun ja maataistelutoiminnan ohella tulenjohtotehtäviin sekä panssarintorjuntaan ja taisteluun helikoptereita vastaan. Pienimuotoiset kuljetustehtävät olivat nekin mahdollisia toteuttaa, sillä konetyypin kuormakapasiteetti on noin 3 000 kg. OV-10 Broncon ensilento tapahtui 16. heinäkuuta 1965.

Yleisimmin saattoi tämä tyyppi käyttää aseistuksenaan maajoukkoja vastaan FFAR-raketteja sekä konekiväärejä, mutta edellisten ohella myös AIM-9 Sidewinder -ilmataisteluohjuksia ja konetykkejä.

Koneen kaksi Garrett AiResearch -potkuriturbiinia tuottivat kumpikin 715 hv tehon. Niiden turvin kone saavutti 452 km/h huippunopeuden, 8 778 m lakikorkeuden ja noin 930 km toimintamatkan.

Konetyyppi tuli tuotantoon vuonna 1966 ja vuonna 1986 päättynyt tuotanto käsitti arviolta 360 koneyksilöä. Alatyypit eli kehitysversiot olivat A—D. OV-10 Bronco osallistui Vietnamin sotaan. 

Palveluskäyttö alkoi tällä konetyypillä elokuussa 1967. OV-10 Bronco on sittemmin poistettu aktiivikäytöstä, Yhdysvalloissa vuonna 1995. Sen käyttäjiä ovat olleet USAF, USMC ja USN. Lisäksi joillakin USA:n liittolaismailla oli näitä tämän tyypin lentokoneita, Euroopassa Saksalla. Konetyypistä on tiettävästi olemassa G-versio -niminen päivitetty muunnos. Sitä käytettäneen edelleen lähinnä terrorismin vastaisessa sodassa.

General characteristics
Crew: two
Length: 12.67 m
Wingspan: 12.19 m
Height: 4.62 m
Wing area: 27.03 m²
Empty weight: 3,127 kg
Max. takeoff weight: 6,552 kg
Powerplant: 2 × Garrett T76-G-410/412 turboprop, 715 hp (533 kW) each
Maximum speed: 452 km/h
Range: 927 km
Service ceiling: 7,315 m
Armament: 4 × 7.62×51mm M60C machine guns
Hardpoints: 5 fuselage and 2 underwing  and provisions to carry combinations of:
Rockets: 7- or 19-tube launchers for 2.75" FFARs or 2- or 4-tube launchers for 5" FFARs
Missiles: AIM-9 Sidewinder (Wing pylons only)
Bombs: up to 250 kg
Other: SUU-11/A or Mk 4 Mod 0 gun pods

The aircraft has responsive handling and can fly for 5 1/2 hours with external fuel tanks. The cockpit has extremely good visibility for a tandem pilot and co-pilot, provided by a wrap-around "greenhouse" that is wider than the fuselage. With the second seat removed, it can carry 1,500 kg of cargo, five paratroopers or two litter patients and an attendant. Empty weight is 3,200 kg. 
Normal operating fueled weight with two crew is 4,500 kg. Maximum takeoff weight is 6,550 kg.

The bottom of the fuselage contains sponsons or "stub wings" that improve flight performance by decreasing aerodynamic drag underneath the fuselage. The sponsons were mounted horizontally on the prototype. Testing caused them to be redesigned for production aircraft. The downward angle assured that stores carried on the sponsons jettisoned cleanly. Normally four 7.62 mm M60C machine guns were carried on the sponsons with the M60Cs accessed through a large forward-opening hatch on the top of each sponson. The sponsons also had four racks to carry bombs, pods or fuel. The wings outboard of the engines contain two additional racks, one per side.

Racked armament in the Vietnam War was usually seven-shot 70 mm rocket pods with white phosphorus marker rounds or high-explosive rockets, or 12,7 mm four-shot Zuni rocket pods. Bombs, ADSIDS air-delivered/para-dropped unattended seismic sensors, Mk-6 battlefield illumination flares, and other stores were also carried.

Operational experience showed some weaknesses in the OV-10's design. It is significantly underpowered. This contributed to crashes in Vietnam in sloping terrain because the pilots could not climb fast enough. While specifications state that the aircraft could reach 7,900 m, in Vietnam, the aircraft could reach only 5,500 m. 
Also, no OV-10 pilot survived ditching the aircraft.

The OV-10 served in the U.S. Air Force, U.S. Marine Corps, and U.S. Navy, as well as in the service of a number of other countries. A total of 81 OV-10 Broncos were ultimately lost to all causes during the course of the Vietnam War, with the Air Force losing 64, the Navy 7 and the Marines 10.

perjantai 3. maaliskuuta 2017

Ryan FR-1 Fireball

The Ryan FR Fireball was a mixed-power (piston and jet-powered) fighter aircraft designed by Ryan Aeronautical for the United States Navy during World War II. It was the Navy's first aircraft with a jet engine. Only 66 aircraft were built before Japan surrendered in August 1945. The FR-1 Fireball equipped a single squadron before the end of the war, but did not see combat. The aircraft ultimately proved to lack the structural strength required for operations aboard aircraft carriers and was withdrawn in mid-1947.

Design of the FR-1 began in 1943 to a proposal instigated by Admiral John S. McCain, Sr. for a mixed-powered fighter because early jet engines had sluggish acceleration that was considered unsafe and unsuitable for carrier operations. Ryan received a contract for three XFR-1 prototypes and one static test airframe on 11 February 1943 with the first two prototypes delivered in 14 months. Another contract was placed for 100 aircraft on 2 December 1943 and a later contract on 31 January 1945 increased the total of FR-1s on order to 700.

The XFR-1 was a single-seat, low-wing monoplane with tricycle landing gear. A 1,350-horsepower (1,010 kW) Wright R-1820-72W Cyclone radial engine was mounted in the fighter's nose while a 7,100 N General Electric I-16 (later redesignated as the J-31) turbojet was mounted in the rear fuselage. It was fed by ducts in each wing root which meant that the wing had to be relatively thick to house the ducts and the outward-retracting main landing gear. To simplify the fuel system, both engines used the same grade of avgas. 

Two self-sealing fuel tanks were housed in the fuselage, one 500 ltr and 190 ltr. The cockpit was positioned just forward of the leading edge of the wing and the pilot was provided with a bubble canopy which gave him excellent visibility. The XFR-1 had the first laminar flow airfoil in a navy carrier aircraft.

The Fireball was armed with four 12.7 mm M2 Browning machine guns with 300 rounds per gun. They were mounted in the center section of the wing, immediately outboard of the air intakes for the jet engine. Four 127 mm rockets could be carried under each outer wing panel and two hardpoints were provided under the center section for 450 kg bombs or 400 ltr drop tanks. Armor plates were provided in front and behind the pilot's seat and for the oil cooler.

The first XFR-1 made its first flight on 25 June 1944 without its jet engine, but that was installed shortly afterward. The second prototype first flew on 20 September 1944. Test flights confirmed wind tunnel tests that revealed a lack of longitudinal stability because the center of gravity had been miscalculated. In addition, the circular rear fuselage of the FR-1 gave less stability than the slab-style fuselage of the Grumman F4F Wildcat that was used as a model for the stability calculations. A new tail with enlarged vertical and horizontal stabilizers was designed and retrofitted to the prototypes. The original Douglas double-slotted flaps proved to be unsatisfactory during flight testing, but all three prototypes and the first 14 production aircraft were built with them before they were replaced with a single-slotted flap.

The first prototype was lost in a crash at NAS China Lake on 13 October 1944. Investigation showed that the wing structure was not strong enough to resist compressibility effects. This was cured by doubling the number of rivets in the outer wing panels. The second prototype crashed on 25 March 1945 when the pilot failed to recover from a dive from 10,670 m, probably also due to compressibility effects. The third prototype crashed on 5 April when the canopy blew off during a high-speed pass over Lindbergh Field.

Operational testing by the Naval Air Test Center at Naval Air Station Patuxent River that included carrier acceptability tests revealed additional problems. The piston engine tended to overheat until electrically operated cowl flaps were installed, the catapult hooks had to be moved and the nosewheel oleo shock strut had to be lengthened by 76 mm. Carrier suitability tests began aboard the escort carrier Charger in early January 1945. The aircraft successfully made five catapult takeoffs using the piston engine as well as three takeoffs using both engines. No problems were reported when landing aboard the carrier.

The FR-1 Fireball was further developed into the XFR-2 which utilized a 1,425 hp (1,063 kW) Wright R-1820-74W in place of the -72W. One single airframe was converted to this configuration. No prototypes were built for the next proposed variant, the FR-3, which would have used a General Electric I-20 turbojet. Both of these projects were canceled with the end of the war. The fastest Fireball was the XFR-4, which had a Westinghouse J34 turbojet and was approximately 161 km/h faster than the FR-1. 

The turbojet's air intakes were moved from the wing roots to the fuselage in front of the wing; they were covered by electrically powered doors to lessen drag when the aircraft was flying only on its piston engine. The Fireball's fuselage was lengthened by 203 mm to accommodate the larger engine and the leading edge extension of the wing root that housed the air intakes was also removed. The XFR-4 was intended to serve as a testbed for the turbojet installation on the XF2R-1 Dark Shark. This was the final variant; the piston engine was replaced with a General Electric XT31-GE-2 turboprop, but only one prototype was built.
General characteristics
Crew: one
Length: 12.19 m
Wingspan: 12.19 m
Height: 4.24 m
Wing area: 25.6 m²
Empty weight: 3,488 kg
Loaded weight: 5,285 kg
1 × General Electric J31-GE-3 turbojet, 7.1 kN, 700 kgf
1 × Wright R-1820-72W Cyclone radial engine, 1,060 kW
Maximum speed: 650 km/h, with piston engine alone 450 km/h
Cruise speed: 246 km/h (piston engine alone) 
Range: 2,610 km with 2 drop tanks
Service ceiling: 13,140 m
Rate of climb: 9 m/s (Piston engine only, with 1 drop tank)
Armament: 4 × .50 in (12.7 mm) M2 Browning machine gun with 300 rpg
2 × 450 kg bombs, 8 × 127 mm rockets under wings

On 2 December 1943, orders for 100 production FR-1s were placed, with a follow-up order of 1,000 additional fighters in January 1945. All of the contracts were contingent on the aircraft successfully completing carrier trials. Only 66 Fireballs were completed by November 1945 as orders for 1,044 FR-1s were canceled on VJ Day

One squadron, VF-66, received its first Fireballs in March 1945, but they never saw combat. On 1 May, three of the squadron's aircraft were craned aboard the carrier Ranger to attempt to qualify seven pilots, but two of the fighters were damaged while landing. One missed the arresting gear and hit the crash barrier while the other aircraft's nose gear collapsed. The following month the pilots qualified and were on pre-embarkation leave when the Japanese surrendered. The squadron was decommissioned on 18 October with all pilots and aircraft transferred to VF-41.
On 6 November 1945, a Fireball of VF-41 became the first aircraft to land under jet power on an aircraft carrier, albeit unintentionally. After the radial engine of an FR-1 failed on final approach to the escort carrier Wake Island, the pilot managed to start the jet engine and land, barely catching the last arrestor wire before hitting the ship's crash barrier. The squadron was attempting to qualify its pilots for carrier operations during this time, but only 14 of its 22 pilots made the six required takeoffs and landings. A number of accidents occurred when the nose gear failed on landing, but the pilots were at least partly responsible as they were slamming the nose gear onto the deck after landing on the main gear.

The squadron qualified on the escort carrier Bairoko in March 1946, but nose gear problems persisted and cut the cruise short. Ryan installed a steel fork for the nosewheel, but inspections also revealed evidence of partial wing failures so the aircraft was limited to maneuvers not to exceed 5 Gs. VF-41 suffered three fatal accidents in 1946 before being redesignated as VF-1E on 15 November 1946. One Ensign collided with the target banner during gunnery practice and spun into the water. A few months later, the squadron commander was performing a barrel roll when his wing broke off and he struck another Fireball, killing both pilots.
VF-1E conducted carrier qualification in March 1947 aboard the escort carrier Badoeng Strait and only eight pilots successfully qualified, not least because the FR-1s were proving to be too fragile to endure repeated carrier landings. During one brief deployment in June aboard Rendova, one aircraft broke in two during a hard landing. Subsequent inspections of the squadron's aircraft showed signs of structural failure and all the Fireballs were withdrawn by 1 August 1947.

After the withdrawal of the type from service, except for a few examples retained for modifications and testing, the FR-1s were scrapped.

sunnuntai 26. helmikuuta 2017

Grumman XF5F

The Grumman XF5F Skyrocket was a prototype twin-engined shipboard fighter interceptor. The U. S. Navy ordered one prototype, model number G-34, from Grumman Aircraft Engineering Corporation on 30 June 1938; its designation was XF5F-1. The aircraft had a unique appearance: The forward "nose" of the fuselage did not extend forward of the wing. Provisions were included for two 23 mm Madsen cannon as armament.
In 1938 Grumman presented a proposal to the U. S. Navy for a twin engine carrier based aircraft, unlike any other fighter aircraft that had ever been considered. The design was for a light weight fighter (under 4500 kg maximum takeoff weight) powered by two 1,200 hp Wright R-1820 engines, with propellers geared to rotate in opposite directions to cancel out the effects of each engine's torque, promising high-speed, and an outstanding rate of climb.

The XF5F Skyrocket was a low wing monoplane with a short fuselage that began aft of the wing's leading edge with a twin tail assembly that featured a pronounced dihedral to the horizontal stabilizer. The main landing gear and tail wheel were fully retractable
The aircraft flew for the first time on 1 April 1940. Engine cooling problems arose in the initial flights, resulting in modification to the oil cooling ducts. Further modifications were made to the prototype including reduction in the height of the cockpit canopy, revising the armament installation to four 12.7 mm machine guns in place of the cannon, redesign of the engine nacelles, adding spinners to the propellers, and extending the fuselage forward of the wing. These changes were completed on 15 July 1941.
General characteristics
Crew: 1
Length: 8.76 m
Wingspan: 12.80 m
Height: 3.45 m
Wing area: 28.2 m2
Empty weight: 3,600 kg
Loaded weight: 4,600 kg
Max. takeoff weight: 5450 kg
Powerplant: 2 × Wright XR-1820-40/42 Cyclone radial, 1,200 hp (895 kW) each
Maximum speed: 615 km/h at sea level
Range: 1,800 km
Service ceiling: 11,000 m
Rate of climb: 1220 m/min
Armament: 4 × 12.7 mm machine guns, + 2 × 75 kg bombs

Testing by Grumman test pilot "Connie" Converse indicated "the flying qualities for the XF5F-1 were good overall. The counter-rotating props were a nice feature, virtually eliminating the torque effect on takeoff ... single-engine performance was good, rudder forces tended to be high in single engine configuration. Spin recovery was positive but elevator forces required for recovery were unusually high. 

All acrobatics were easily performed, and of course forward visibility was excellent."
In 1941, Navy pilots tested the XF5F-1 in a fly-off against the Supermarine Spitfire, Hawker Hurricane, Curtiss P-40 Warhawk, Bell P-39 Airacobra, Bell XFL Airabonita, Vought XF4U Corsair, Grumman F4F Wildcat, and Brewster F2A Buffalo.

LCDR Crommelin, in charge of the test, stated in a 1985 letter to George Skurla, Grumman president, "for instance, I remember testing the XF5F against the XF4U on climb to the 10,000 foot level. I pulled away from the Corsair so fast I thought he was having engine trouble. The F5F was a carrier pilot's dream, as opposite rotating propellers eliminated all torque and you had no large engine up front to look around to see the LSO (landing signal officer) ... The analysis of all the data definitely favored the F5F, and the Spitfire came in a distant second. ... ADM Towers told me that securing spare parts ... and other particulars which compounded the difficulty of building the twin-engine fighter, had ruled out the Skyrocket and that the Bureau had settled on the Wildcat for mass production."

Additional changes were needed after further flight tests that were not completed until 15 January 1942. In the meantime, Grumman began work on a more advanced twin-engine shipboard fighter, the XF7F-1, and further testing with the XF5F-1 supported the development of the newer design. The prototype continued to be used in various tests, although plagued by various landing gear problems, until it was struck from the list of active aircraft after it made a belly landing on 11 December 1944.

The XF5F Skyrocket was the only propeller fighter aircraft flown by the Blackhawks in Quality Comics monthly title Military Comics, which ran throughout World War II. The XF5F remained the Blackhawk Squadron's mount until their conversion to jet aircraft in Quality's retitled Modern Comics at the start of the jet age.