Ian Strachan provides an overview of military flight simulators and training equipment. He also makes an argument that 'g' and 'anti-g' is neglected in many fighter jet full mission simulators. In 2007 there were about 1470 military flight training devices worldwide with either a motion platform and/or a visual system. These range from dome-based Full Mission Simulators (FMS), to Unit Level Trainers (ULT), some of which have only one visual display window. See a listing by aircraft type in MS&T’s Military Flight Simulator Census, published in MS&T 3/2007.
Some 750 (51%) of these aircraft training devices are in the USA. Not surprisingly the list is headed by the US Air Force with about 400, followed by the US Navy with about 140, US Army with 90 and the US Marine Corps with 50. About 60 others are shared between the Navy and Marines and the remainder are for the US Coastguard and at a number of civil-owned training centres that carry out military training. No other country comes close, France being next with about 70, Germany and the UK with around 60 each and then Canada with 30. Below this come a number of countries with about 20 each. These are Australia, Brazil, Italy, Japan, South Korea, the Netherlands, Saudi Arabia, Spain and Taiwan. There must be quite a few military simulators in the People's Republic of China (PRC) and Russia. However, figures here are difficult to find, although the Nanjing Research Institute for Simulation Technique (NRIST), the Penza Simulation Bureau in Russia, and no doubt other manufacturers, have made quite a number of simulators for their own militaries. Other than the countries mentioned above, some 40 other countries have smaller numbers of military simulators.
L-3 Link is the lead manufacturer with just over 220 military flight training devices with either visual or motion features in current service. Link is followed by CAE with about 210; Thales with 200; Boeing with 170; and no less that 28 other manufacturers with between 5 and 50 each. The CAE figure includes plants in Canada, Germany and USA; Thales numbers include its predecessors Rediffusion, Singer-Link-Miles and Thomson; and Boeing includes the ex-McDonnell Douglas Training Systems (MDTS) company.
Fighter Aircraft Simulators
A feature of European-designed simulators for the Typhoon and Tornado is that they have several systems for cueing in high-G situations. A conventional 6-jack motion platform works well in the centre of the aircraft envelope, but cannot give cues of sustained vertical G. For that reason most fighter simulators are not fitted with motion platforms, as are Full Flight Simulators (FFS) for civil airliners, many large multi-engined military aircraft and military helicopter simulators.
However, in European designs for fighter simulators, simulator-specific G-seats are in common use. These give a number of effects when the simulator computer registers high G. These include seat-pan lowering, pressure pads in the seat back and seat pan, and variable shoulder-strap tension. Seat pan lowering simulates the body slumping that occurs under real G and causes the pilot to make an effort to stretch to maintain his eye-point, as would happen in the real aircraft. Inflatable pressure pads in the backrest give cues of horizontal acceleration and inflatable pads in the seat pan give cues of vertical G (so-called "seat-of-the-pants" cues). Strap tightening and loosening can give cues of both positive and negative G (with a safety cut-out to protect the pilot from being squashed). Finally, some G-seats are capable of small motions in some of the six-degrees of freedom. In the case of Tornado simulators, G-seats by CAE and Cranfield Aeronautics (UK) are in use, and in Typhoon simulators, G-seats by Moog FCS (ex Fokker Controls) and Cranfield.
The capability to inflate the pilot's anti-G suit is also important for realism of G cues in the simulator. This has the added benefit that pilots must wear their normal flying kit during Mission Simulator training, thus increasing the overall realism of a simulator sortie. There is a school of thought that if a Full Mission device is to be used for Full Mission training, then the mission kit should be worn and the cockpit environment should be as close to the real aircraft as possible. Some simulator G-seat systems incorporate G-suit inflation as an integral part of their design. Where they do not, independent simulator anti-G suit inflation systems are available from Thales and others.
Then there are the visual effects of high G. In real aircraft these effects are precursors to the highly dangerous G-induced Loss of Consciousness (G-LOC). This is potentially lethal and several aircraft and pilots have been lost in G-LOC accidents. I have practical experience of these symptoms from centrifuge runs carried out at the UK research base at Farnborough. This was part of research to develop the anti-G systems now fitted to the Eurofighter Typhoon aircraft, which like many fighter aircraft has a 9-G limit. In this research, variables included seat rake angle, anti-G suit pressure, leg/rudder pedal positions and arm positioning and support. Some other factors were also found to help a pilot sustain high G more comfortably, but these would need another article. In the aircraft, as G values reach 7, 8 and 9, the pressure in the anti-G suit combined with the pilot's physical straining manoeuvre, no longer prevents blood from draining from the head. As G increases to critical values, colour vision is lost, peripheral vision progressively reduces ("tunnel vision"), vision goes altogether and finally consciousness is lost ("black out"). Just before consciousness is lost, a strange condition sometimes referred to as "grey out" occurs. This is where the pilot is still conscious but has no sight. Unless a reduction in G is quickly made, unconsciousness will almost inevitably follow. It might be thought that a reduction of G would result in a rapid recovery of pilot faculties. Unfortunately, after a G-LOC event followed by a reduction of G, there is a period of up to 10 seconds of disorientation before a pilot recovers enough to apply judgement in assessing the situation. The potential for disaster is clear.
In the light of this, I would suggested that, for high-G aircraft (1) the above effects should be incorporated in Full Mission Simulators and (2) regular and realistic training to prevent G-LOC is vital. Taking the latter first, I have argued that each major fighter base that has high-G aircraft should have a training centrifuge with a cockpit section representative of the aircraft. Unfortunately, this does not seem to be done by any Air Force, European or otherwise, presumably on grounds of cost. However, even one G-LOC accident would pay for several man-rated centrifuges, aside from the human cost. On simulator visual systems, so called "G-dimming" is easy to incorporate. In the case of Typhoon simulators manufactured by the Eurofighter Simulation Systems (ESS) consortium, the CAE Medallion X image generator produces the tunnel-vision effect under high computed G and if the simulator pilot persists in increasing G, the image generator "blacks out". Compared to more difficult things such as adding large-area high-resolution databases, G-dimming is straightforward to achieve.
F-15, 16, 18 Simulators
Let us now look at simulators for the F-15, F-16, F-18 and F-35 fighters. Some 900 F-15 Eagle aircraft were made, of which about 700 are still flying. There are about 90 F-15 simulators, an aircraft-to-simulator ratio of about 8:1. About 55 are by Boeing and its predecessor company McDonnell Douglas Training Systems (MDTS), 25 by Lockheed Martin and the rest by BVR (Israel) and Mitsubishi (Japan).
Over 4,000 F-16 Falcons have been built, of which about 3000 are still in service, and production continues. Simulators include about 115 by L-3 Link, 25 by Lockheed Martin, 15 each by Thales and Boeing, and others by Elbit (Israel), Sogitec (France) and Singapore Electronics. This totals 190 simulators, an aircraft-to-simulator ratio of 15.8.
In the case of the F-18 Hornet, some 1460 aircraft have been produced, of which about 1400 are still flying, and production continues. Simulators include about 50 by L-3 Link, 30 by Boeing and others by CAE (Canada), Indra (Spain) and Lockheed Martin, a total of about 90. The aircraft-to-simulator ratio is 15.6, very similar to that for the F-16.
F-35 JSF Simulators
The F-35 Lightning 2 Joint Strike Fighter (JSF) is the largest ever international collaborative aircraft programme (see www.jsf.mil ). Lockheed Martin leads the industry team with Northrop Grumman and BAE Systems as principal industrial partners. The first production aircraft flew in December 2006, a demonstrator having flown in 2000. Final assembly of the F-35 will be by Lockheed Martin Aeronautics in Fort Worth. The Northrop Grumman Corporation at Palmdale and El Segundo will manufacture the centre fuselage, and the aft fuselage and tail surfaces will be manufactured by BAE Systems in Salmesbury, UK. Lockheed Martin in Fort Worth will manufacture the forward fuselage and wings. Some 3100 F-35 aircraft are to be made, not only for the US Air Force, Navy and Marine Corps but also for Australia, Canada, Denmark, Israel, Italy, Netherlands, Norway, Turkey and the UK. A number of other countries are reported to be interested. There are three variants, the F‑35A for conventional takeoff and landing (CTOL), the F‑35B short takeoff and vertical landing (STOVL) for the UK and US marine Corps, and the F‑35C carrier based (CV) variant for the US Navy that has a larger, folding wing and is strengthened for catapult launching and arrested landing.
The prime contractor for the F-35 training system is Lockheed Martin Simulation, Training and Support (LM-STS). The Lockheed Martin plant at Akron is integrating the pilot trainers. Training system programme manager JoAnne Puglisi says that the first hardware is already arriving. Lockheed Martin Akron has previously made some fighter simulators including for the F‑15 and F‑16. The F-35 system will include Full Mission Simulators (FMS), Deployable Mission Rehearsal Trainers (DMRT) and Computer Based Training (CBT), backed by courseware and a training management system (TMS). An Integrated Training Centre (ITC) will be established at Eglin Air Force Base in NW Florida for all three F-35 variants. Other ITCs will be in Australia, Turkey and the UK, and maybe in other countries. Training at Eglin is scheduled to start in February 2010 for the F‑35A and October 2010 for the F‑35B STOVL variant. About 80 percent of the training syllabus will be common to all variants. At Eglin, there will be 10 Full Mission Simulators and 6 maintenance training devices, plus classrooms and a training system support centre. The FMS will have a SEOS 360 degree 2-metre diameter dome display with 25 liquid‑crystal‑on‑silicon (LCoS) projectors. Image generation will be from 23 Rockwell Collins EPX channels. Simulator-to-aircraft sortie ratio is planned to be 1:1 with longer sorties on the simulators, so simulator time will be more than aircraft time (after all, it's a lot cheaper!). The less-complex DMRT design has two cockpits with smaller visual displays and is mounted in a container that can be easily transported from site to site. Maintenance trainers are an integral part of the overall training system and the UK company EDM is building the first ejection seat and weapons loading trainers. Turning to the F‑35 aircraft itself, it is to have embedded simulation and will have the US military P5 range-less GPS-based combat training system.
To finish, a few words about simulators for helicopters and large multi-engined types. For these, high-G does not apply and the 6-jack simulator motion platforms used in airliner simulators are commonly used. There are about 350 military helicopter simulators worldwide. In the UK, Private Finance Initiative (PFI) or Public-Private Partnership (PPP) training is common. At Benson near Oxford, CAE has motion-based helicopter simulators with wide-angle visuals for Chinook, Merlin and Puma Support Helicopters (SH) and ATIL has motion-based domes at Middle Wallop for Apache Attack Helicopter (AH) training. The USA has about 150 helicopter simulators, 85 for the US Army, about 25 each for the Navy and Marines, and 12 for the US Air Force, others being for the Coastguard and at company-run training centres.
Multi-engine Aircraft Simulators
For military multi-engine heavy aircraft, there are about 275 simulators worldwide, of which nearly 200 are in the USA. An example is the C-17 Globemaster III simulator design, made by Flight Safety International (FSI). This has 6-jack motion platforms using electrics rather than hydraulics, giving lower transport delay (latency) and less maintenance. These simulators, like many other military simulators for heavy aircraft, are effectively to a "Level D plus" standard, the plus features (over airliner training requirements) being the military additions such as Air Refuelling, formation flying, STOL operations and low-level air load dropping.
This overview of some aspects of military simulation shows that state-of-the-art training systems are indeed being deployed. Although to this author the lack of G-cueing systems in many fighter simulators is difficult to understand. In my opinion, a Full Mission Simulator sortie should be just that, as close to the Full Mission as possible, in all aspects including some that may involve discomfort or inconvenience. That is what realistic training should be about.
Editors’ Note - The opinions expressed in this article are those of the author. They do not necessarily reflect those of MS&T's editorial board or advertisers.
Published in MS&T Magazine Issue 1/2008
Source: Halldale.com - Article