On 9 February at the YMCA Hawker centre Robin Trewinnard-Boyle spoke to Members present and on Zoom mainly about the UK F-35B flight tests and sea trials. Chairman Chris Roberts introduced the speaker saying that he commenced his Royal Navy Air Engineering career on fixed wing and rotary wing aircraft, had staff tours ashore and on aircraft carriers, and started on the Sea Harrier FA2 before moving onto the Harrier GR7 and T10. In 2011, following the scrapping of HMS Ark Royal, he was selected the Military Maintenance Officer of the F-35 Integrated Test Force. Knowledge gained there was used in the Carrier Strike Capability Development Team in its preparation for the UK F-35B Sea Trials and Ship-Air Integration work. Robin left the RN in 2018 and now works for Nova Systems International, involved in flight test and evaluation on Typhoon. Robin is also a serving Reservist for the Lightning II Delivery Team. In his career in the RN and Flight Test Robin was following in the footsteps of his Grandfather, Geoffrey Trewinnard, who, following his demob from the RN in 1945, joined Hawker as a Flight Test Engineer. Geoffrey worked on the Sea Fury, Sea Hawk and Hunter.
    Robin’s role in the F-35 service clearance programme as the Senior Military Engineering Officer was the focal point for coordination with Lockheed-Martin and the five services in the programme; USMC, USN, USAF, RN and RAF. There were five F-35Bs and four F-35Cs involved.

F-35b Flight Testing And Ship Trials
    There are three versions of the F-35 (a 5th generation fighter): the conventional take-off and landing (CTOL) F-35A, the short take-off and vertical landing (STOVL) F-35B and the catapult and arrested landing (CV) F-35C. The F-35B, developed in conjunction with BAE Systems, was for the USMC and the RN/RAF for operation on two the Queen Elizabeth (QE) class carriers . However, in the 2011-2012 period, with the carriers in build and the aircraft programme well under way, the UK Government changed its mind under RN pressure, and thought that the F-35C would be preferable because of its slightly greater range than the STOVL B model. A very expensive study ensued. It was realised that the QEs, designed for STOVL, had no catapults or arrester gear, although there was space, and the ships were gas turbine powered so there was no steam on tap for the catapults making the only option electromagnetic power - which did not exist full scale at the time; development would be very costly and the ships would be delayed by some years. So, back to square one, the F-35B!
    The F-35 missions are suppression of air defences flying in the clean, stealthy configuration, by day or night; fly deeply into heavily defended areas; locate, identify and destroy relocatable or moving targets; all while possibly outnumbered by 4th generation fighters which can’t see the stealthy F-35 but which the F-35 can see.
    Trials took place at four sites: Naval Air Station, Patuxent River (Pax River), Maryland; Marine Corps Air Station (MCAS), Beaufort, South Carolina; Eglin Air Force Base (AFB), Florida; and Edwards AFB, California. The Joint Project Office (JPO) was at Arlington, Virginia and the manufacturer was Lockheed-Martin at Fort Worth, Texas, with its mile long production line. (Editor’s note. The UK is a Tier 1 partner, the main contributions being: BAES builds all the F-35 rear fuselages, and Rolls-Royce supplies the jet lift systems including the fan for the B model)
    The US/UK F-35 Integrated Test Force (ITF) had five F-35Bs and four F-35Cs including the first UK aircraft, serial number ZM135 (like the first English Electric Lightning F1 accepted by the RAF, XM135). All were instrumented. Two of the F-35Bs were devoted to mission systems testing and three to flight systems testing. The ITF was manned by 600 contractors’ personnel and 324 government personnel.
    The ITF trials included flight and ground safety, flight envelope expansion, software development testing, aerodynamic properties (handling and stability and control) in conventional and STOVL flight, survival equipment, especially the helmet with its visor display which, by means of airframe mounted external cameras, gives the pilot all-round vision including seeing through the cockpit floor. The mission system includes the radar and other sensors, information from which is displayed on a large screen taking up most of the panel space in front of the pilot who can see all the relevant information at once instead of looking at a number of smaller dedicated screens found in ‘legacy’ aircraft. All this information can be shared with other F-35s and all suitably equipped command and control bodies involved in the battle.    
    Facilities unique to Pax River were concerned with carrier suitability, STOVL, the Ski Jump, the hover pit and low observables/radar cross section (stealth) testing. Unique to Edwards were its long runways, flat desert surroundings, weapon ranges, an artificially wet runway, multi aircraft mission systems testing and engine-stopped testing facilities. Its remote location also ensured security - Russian electronic information gathering ‘trawlers’ were not around to gather electronic intelligence. Eglin AFB provided training facilities for ground and air crew and had a comprehensive climatic hangar for hot, cold and wet ground testing and running.
    Weapons integration testing was in two phases: internal carriage for stealthy operation (day one of the war) and external carriage for non-stealthy operations once the enemy surface to air weapon systems are disabled. The internally carried stores cleared were: the Joint Direct Attack Munition (JDAM), an all weather, precision guided bomb; the Paveway laser guided bomb; and the AIM-120 Advanced Medium Range Air-to-Air Missile (AMRAAM). Sidewinder AIM-9X air-to-air missiles were carried on the wing outboard pylons. A range of US and UK weapons was cleared for use on the six under wing pylons. A US 25 mm gun pod was cleared for under fuselage centre line carriage (not for UK use at present).
    The night vision system was tested for correct operation with the helmet mounted display. Any effects of the adjacent aircraft on engine surge sensitivity were explored in formation flying. Correct engine functioning was tested at high angles of attack as was aircraft handling with the engine stopped. Probe and drogue air-to- air refuelling from the C-130, and Tristar was carried out .
    The initial sea trials, DT-1, were carried out on USS Wasp in October 2011. This trial was crucial  because at this time the UK was heading for the F-35C so the future of the USMC committed to the type depended on the trial’s success. Areas covered were deck handling and manoeuvring, tie down, systems performance during carrier approach and landing, vertical landings (VL) in varying wind conditions, nominal and excess speed short take-offs (STO), deck edge clearance during STO, effects of airflow round the ship on STO and VL, deck markings and lighting, development of procedures, operating limits and techniques and STOL-mode helmet display symbology. The trial was extremely successful assuring the future of the USMC - and also in due course the effectiveness of the RAF/RN when the B version was confirmed as the UK choice.

DT-2 sea trials were in August 2013, again on USS Wasp. Here the operating envelope was expanded, external stores were flown, initial night STOs and VLs were carried out, operations with increased deck motion, and wet deck operations were carried out, landing aids were tested, updated mission system software was tested and a production standard aircraft (BF-5) was checked out. Vertical take-offs, although not a requirement, were successfully demonstrated.

    DT-3 sea trials were on USS America, in December 2015. Here the aircraft operating envelope was developed, refined and expanded, data was collected for updated mission system software, launch and recovery was flown with increased deck motion and with heavy external and asymmetric loads, the improved Gen 3 helmet was tested, embarked maintenance and logistics were exercised including an engine change, as was the approach and landing instrument system.
    Other trials covered: further US under fuselage gun pod firing, expeditionary testing using austere sites, the integration and release of UK weapons - ASRAAM outboard underwing instead of Sidewinder and Paveway 4 laser guided bombs on the middle and inboard underwing - airfield ski-jump launches, and air-air refuelling with the RAF, Airbus A-330 derived, Voyager tanker.
    The above testing allowed the F-35B to be tested on the HMS Queen Elizabeth in the First of Class Flight Trials (FOCFT) in the Autumn of 2018. This 65,000 ton, 25 plus knots CVF type vessel with a crew of 1450 is 280 metres long (vs. the 194 m of the Invincible class) with a total capacity of 40 F-35Bs. The FOCFTs were to generate a carrier strike capability with an Initial Operational Clearance (IOC) in December 2020.
    FOCFT DT-1 and 2 achieved 200 Ski Jump STOs, 187 VLs, and 15 short rolling vertical landings (SRVLs).The latter consists of an axial, nozzle deflected/fan-on, approach to the carrier at a speed necessary to generate enough wing lift to enable landing back on the carrier with unexpended (expensive) weapons in hot weather conditions where a jet borne VL is not possible. SRVL and Ski-Jump modelling had previously been carried out on a BAES Warton flight simulator incorporating a landing signals officer (LSO) training facility. In addition 54 dummy weapons were released. Also, the cross wind effects of the unique twin island architecture were explored during STOVL. Such was the success of DT-1 and 2 that the planned DT-3 was cancelled and the joint Operational Trial (OT) went ahead with RAF Squadrons 17 and 617 and USMC Squadron VMA 211 participating.
    Running short of time Robin stopped here and was rewarded with many questions from the well informed audience, several of whom had been intimately involved in Harrier and Sea Harrier ship trials and Ski Jump development trials. The vote of thanks for this comprehensive and informative talk was given by Frank Rainsborough. Please visit the HA online video library for a recording of this talk.
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