Author Topic: Sikorsky/Westland S-67 Seahawk HAR-7  (Read 3081 times)

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Offline lenny100

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Sikorsky/Westland S-67 Seahawk HAR-7
« on: November 18, 2010, 03:23:11 pm »
In December 1962, Combat Development Command (CDC) drafted a Qualitative Material Requirement (QMR) for an interim, commercial off-the-shelf (COTS) aircraft, with a 140knot (161 mph, 259 km/h) cruise speed and a 1,500-pound (680 kg) payload.
This was seen as an attempt by Army officials, anticipating the potential of the D-255 helicopter gunship concept, named "Iroquois Warrior", to acquire an interim aircraft to fill the escort role until the Army could determine the requirements for a dedicated armed helicopter, however, the Secretary of the Army disapproved the interim approach and directed that the Army look for a more advanced system that would dramatically improve over current helicopter designs.
Based on the guidance from the Secretary of the Army, CDC established Qualitative Material Development Objectives (QMDO) for a rotary-wing aircraft with 195-knot (224 mph, 361 km/h) cruise speed, 220-knot (253 mph, 407 km/h) dash speed, and the capability to hover out-of-ground-effect (OGE) at 6,000 feet (1,830 m) on a 95 F (35 C) day. The speed requirements were derived from the speed of aircraft the helicopter would escort.
The Director of Defence Research and Engineering (DDRE) conditionally approved the changes to the development objectives, pending his review of the proposed program. He also directed the Army to determine whether or not any other helicopter could offer an improvement in performance over the UH-1B in the meantime as a result, the Army Material Command (AMC) conducted a study to determine if the development objectives were feasible and also established a Program Manager's office for the Fire-support Aerial System (FAS).
AMC recommended narrowing the competition to compound helicopters, as they were considered the only helicopter configuration at the time capable of being developed to meet the objectives.
In March 1964, the Secretary of the Army advised DDRE that modification of existing aircraft would not approach the required performance of the FAS program; the Army would continue using UH-1B aircraft until development of the FAS could proceed.
On its own, Bell went forward with the company-sponsored model 209 AH-1 based on the UH-1 Huey, first flying in 1965.
Proponents opposed buying the AH-1, but director of Army Aviation Colonel George P. Seneff told Chief of Staff General Harold K. Johnson and Vice Chief of Staff General Creighton Abrams that the soldiers were "dying now, not in the future".
General Johnson made the decision to order the simpler AH-1G Cobra attack helicopter in 1966 as an interim attack aircraft for combat in Vietnam.
On 26 March 1964, the Army Chief of Staff designated the FAS program as the Advanced Aerial Fire Support System (AAFSS). The development objectives document (QMDO) for the AAFSS was approved in April 1964, and on 1 August 1964, the Transportation Research and Engineering Command contacted 148 prospective contractors with a request for proposals (RFP).
The Army announced Lockheed and Sikorsky as winners of Project Definition Phase contracts on 19 February 1965.
Each company developed proposals for their respective designs, establishing three configurations to satisfy both the development objectives and a revised RFP based on a draft requirements document. [15]
 Lockheed offered its CL-840 design, a rigid-rotor compound helicopter, which became the AH-56 Cheyenne

Sikorsky submitted the S-66, which featured a "Rotorprop" serving as a tail rotor but as speeds increased would rotate 90 to act as pusher prop.

The S-66 had short, fixed wings and was powered by a 3,400 shp (2,500 kW) Lycoming T55 turboshaft engine.
The design was to have a speed of 200 knots (370 km/h) with the ability for 250 knots (460 km/h) for brief periods.

An evaluation board studied each company's proposal and then submitted its recommendation to a selection authority council on 6 October 1965. On 3 November 1965, the Army announced Lockheed as the winner of the AAFSS program selection. The Army perceived Lockheed's design as less expensive, able to be delivered sooner, and a lower technical risk than Sikorsky's Rotorprop. On 17 December 1965, the Army released the final requirements document. The document added fourteen requirements that were not previously addressed by Lockheed's proposal, including the addition of an aerial rocket armament

 S-67 development
When the Armed Aerial Fire Support System program was delayed due to problems with the flight testing of the Cheyenne, Sikorsky offered the army an armed version of its successful SH-3 Sea King (Sikorsky S-61), but it was not taken up, but the company decided to design and developed the Sikorsky S-67 Blackhawk high speed attack helicopter as a private venture in 1970 with one eye on overseas sales.
The S-67 featured a five-bladed main rotor and tail rotor taken from the S-61, but was modified to have a hub fairing, swept main rotor blade tips and a special "alpha-1" linkage which was added to the main rotor controls to increase collective pitch sensitivity and so extend the collective pitch range.
The 20 swept main rotor blade tips help to overcome a phenomenon called sub-multiple oscillating track (SMOT) that causes variations in tip track at high Mach numbers. These allowed the S-67 to achieve and maintain high cruise speeds. To reduce drag at high speed, the main wheels retracted fully into the stub wing sponsons. It had speed brakes on the wing trailing edges that could be used to decrease speed or increase manoeuvrability.

The S-67 Blackhawk, along with the Bell 309 "King Cobra", was put through a series of flight test evaluations in 1972 by the U.S. Army.
The S-67 performed a series of aerobatic manoeuvres during its various marketing tours, including rolls, split-S, and loops. The S-67 was reputed to be very smooth and responsive, in spite of its size and speed.

Piloted by Sikorsky Test Pilots Kurt Cannon and Byron Graham, the S-67 established two E-1 class world speed records on 14 December 1970 by flying at 348.97 km/h (217 mph) over a 3 km (1.9 mi) course and 355.48 km/h (221 mph) on 15 to 25 km (9.3 to 16 mi) course on 19 December 1970. These records stood for 8 years.

As part of internal Sikorsky R&D efforts, in 1974 the S-67 had a 3.5-foot (1.1 m) diameter ducted fan fitted instead of its original conventional tail rotor. In this configuration it reached a speed of 230 mph (370 km/h) in a test dive.  The original tail rotor and vertical tail fin were re-installed in August 1974.
 Fatal crash

The first S-67 prototype crashed while conducting a low-level aerobatic demonstration at the Farnborough Air show in September 1974.
 During a low-level roll manoeuvre, the nose dropped below the horizon resulting in a momentary descent which eliminated the altitude safety margin for a safe completion of the manoeuvre. The aircraft struck the ground in a level attitude and immediately burst into flame. Sikorsky test pilot Stu Craig died on impact, and test pilot Kurt Cannon died nine days later from his injuries.

The U.S. Marine Corps was very interested in the AH-1G Cobra, but preferred a twin-engine helicopter for improved safety in over-water operations, and also wanted a more potent turret-mounted weapon. At first, the Department of Defence had balked at providing the Marines with a twin-engine helicopter in the belief that commonality with Army AH-1Gs outweighed the advantages of a different engine fit.
However, the Marines won out and awarded Sikorsky with a contract for 49 Blackhawks in May 1974.
The Marine Corps requested greater load carrying capability in high temperatures for the Blackhawk in the late 1970s.
Sikorsky designed the AH-1B to be more reliable and easier to maintain in the field. The version was given full TOW missile capability with targeting system and other sensors. An advanced version, known as the AH-1B+ with more powerful T700-GE-700 engines and advanced avionics was proposed to Iran in the late 1970s, but the overthrow of the Shah of Iran resulted in the sale being cancelled.

In the early 1980s, the U.S. Marine Corps sought a new navalized helicopter, but was denied funding to buy the AH-64 Apache by Congress in 1981. The Marines in turn pursued a more powerful version of the AH-1B. Other changes included modified fire control systems to carry and fire AIM-9 Sidewinder and AGM-114 Hellfire missiles. The new version was funded by Congress and received the AH-1C designation. Deliveries of AH-1C Blackhawk totalled 179 new-built helicopters plus 43 upgrades of AH-1As

The AH-1B+ demonstrator and AH-1C prototype was later tested with a new experimental composite five blade main rotor system. The new system offered better performance, reduced noise and improved battle damage tolerance. Lacking a USMC contract, Sikorsky developed this new design into the AH-1E with its own funds. By 1996, the Marines were again not allowed to order the AH-64. Developing a marine version of the Apache would have been expensive and it was likely that the Marine Corps would be its only customer. They instead signed a contract for upgrading 180 AH-1Cs into AH-1Es.

The AH-1E renamed Seahawk features several design changes. The AH-1E's two redesigned wing stubs are longer with each adding a wing-tip station for a missile such as the AIM-9 Sidewinder. Each wing has two other stations for 70 mm (2.75 in) Hydra rocket pods, or AGM-114 Hellfire quad missile launcher. The Longbow radar can be mounted on a wing tip stations

Westland Seahawk

Westland Helicopters, which had a long standing licence agreement with Sikorsky to allow it to build Sikorsky's helicopters, extended the agreement to cover Sikorsky Blackhawk soon after the first flight in 1971.
The Royal Navy selected the helicopter as support for the Royal Marines and to escort its new Seaking troop transports in 1975.
The Seahawk was selected over its rivals such as the Cobra due to it unrefuelled combat range of over 400 miles which enabled it to close escort the troop carrier Sea King helicopters and then support the landed troops for extended periods.
The HAR-7 which is an anglicised US Marines AH-1-E was first flown in 1999.
It is a remanufactured HAR-6 airframe originally built by Sikorsky in 1975 but updated over the years, to zero the flight hours and then fitted with two Rolls-Royce Turbomeca RTM322-01 turboshafts and the advanced rotor system as fitted to the new Merlin HC3A.
The cockpit is fitted with armoured seats for the crew as well as them sitting in an armoured tub, and can withstand an impact velocity of over 10 m/s. Dual flight controls are provided, though the helicopter can be flown by a single person. The pilot's instrument displays include six full colour high-definition screens and an optional mission display. A digital map and Forward-Looking Infrared system display are installed on the gunners displays only
The Seahawk has been cleared to operate from the Royal Navy's aircraft carriers, amphibious assault ships, Type 23 frigates and a number of RFA vessels including the Fort Victoria Class.
It is also intended to equip the forthcoming Type 45 destroyers and type 26 sea control ships.

A Capability Sustainment Programme is currently in place to upgrade 30 aircraft to the HM-8 standard. This will include a new mission system and digital cockpit, a SELEX Galileo Seaspray 7000E active electronically scanned array (AESA) radar and cability to carry the Future Air-to-Surface Guided Weapon (FASGW) . It had been planned to include the remaining 18 airframes but this has now been dropped for financial reasons while alternative roles were sought for these aircraft.

load out

Gun: 1M230 20 mm Chain Gun, 2567 rounds
Wing load out: 960 kg (2,116 lb.) of  2 anti-ship missiles , 4 homing torpedoes , 4 depth charges, 6 Brimstone  or  4 rocket pods

This aircraft is shown in the 2009 special markings for the Fleet air arms 100th birthday.

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Offline philp

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Re: Sikorsky/Westland S-67 Seahawk HAR-7
« Reply #1 on: November 18, 2010, 05:51:27 pm »
Seen the pics from SMW.  Very cool.  The first 3 pics don't show in the thread (photobucket removed) but the last 2 do.
Phil Peterson

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Offline BrittMac

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Re: Sikorsky/Westland S-67 Seahawk HAR-7
« Reply #2 on: November 18, 2010, 09:34:54 pm »
Lenny, nice story and great job on the kit.  Love all the new bits.

Offline Army of One

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Re: Sikorsky/Westland S-67 Seahawk HAR-7
« Reply #3 on: November 22, 2010, 03:57:19 pm »
Oh......great backstory n awesome it.....can't see first 3 pics for reason already given but the last 2 are great...... :thumbsup:


Offline Weaver

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Re: Sikorsky/Westland S-67 Seahawk HAR-7
« Reply #4 on: November 23, 2010, 04:11:47 am »
Excellent piece of work Lenny - well done!  :thumbsup:
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Offline KiwiZac

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Re: Sikorsky/Westland S-67 Seahawk HAR-7
« Reply #5 on: December 14, 2010, 02:40:00 am »
Great to see a whif S-67 model at long last! Top work and a great backstory to boot. Have you any other pics?
With warm regards from Whanganui, New Zealand

Offline Stargazer2006

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Re: Sikorsky/Westland S-67 Seahawk HAR-7
« Reply #6 on: December 14, 2010, 07:12:21 am »
My favorite combat helo ever... More pics, PLEAAAAASE!!!!!  ;D  :thumbsup:
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Offline James

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Re: Sikorsky/Westland S-67 Seahawk HAR-7
« Reply #7 on: December 14, 2010, 08:57:38 am »
It's a beauty!  :wub:

Offline McColm

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Re: Sikorsky/Westland S-67 Seahawk HAR-7
« Reply #8 on: December 15, 2010, 04:04:29 am »
Well done :thumbsup:

Offline chrisonord

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Re: Sikorsky/Westland S-67 Seahawk HAR-7
« Reply #9 on: December 15, 2010, 03:26:33 pm »
I do like this Lenny, pity there isn't a styrene kit of this available, as I would like a few of these to do in USMC markings
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Offline Pablo1965

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Re: Sikorsky/Westland S-67 Seahawk HAR-7
« Reply #10 on: December 15, 2010, 03:31:25 pm »
Sikorsky and Westland is like water and oil but your bug is so cool and realistic.... :thumbsup: :cheers: :bow: :ph34r: :ph34r: :ph34r: :ph34r: