An Overview of the T-X Trainer Program

Korean TA-50 trainer/light attack aircraft taxi on a runway.

Korean TA-50 trainer/light attack aircraft taxi on a runway.

In recent years, the United States Air Force has launched a number of programs intended to replace aging aircraft with modern ones. Most of these programs are in various stages of completion; the Advanced Tactical Fighter program yielded the F-22, the Joint Strike Fighter program yielded the F-35, KC-X produced the KC-46 Pegasus tanker, and Long Range Strike Bomber program chose Northrop Grumman’s proposal. However, there are a few aircraft in the USAF’s inventory still due for replacement. One of these is the Northrop T-38 Talon, a twin-engine supersonic jet trainer aircraft.

Trainer aircraft are used to teach USAF pilots the fundamentals of manned flight through practice and cockpit experience. Trainer aircraft compliment other teaching methods, such as classroom instruction and simulators, by affording pilots experience in a real aircraft. After all, flying an aircraft is not only a mental but also a physical skill, and honing one’s abilities in a real aircraft is an indispensable element of training.

The USAF operates multiple classes of trainer aircraft. Students begin on the T-6 Texan II, a single-engine turboprop aircraft. Once they master the basic flight skills on the Texan II, students move on to the T-38 Talon, which bridges the gap between the turboprop Texan II and a full-scale jet fighter.

A T-38 Talon trainer flies in formation while its wingman rolls to the left.

A T-38 Talon trainer flies in formation while its wingman rolls to the left.

Introduced in 1961, the T-38 is largely obsolete. The average USAF T-38 is over 40 years old, so the airframes have been subject to significant structural stress and are in need of replacement. Also, the T-38 is also unable to provide training on the kinds of high-tech systems featured aboard new USAF aircraft such as the F-22 and F-35, which have large LCD avionics displays and advanced helmets. The T-38, being over fifty years old, is simply no longer state of the art, and it does not smoothly integrate with the digital, simulator-heavy training regimes now favored by the USAF. T-X will feature the ability to train pilots not only on flight dynamics but also on high-tech operations such as datalink usage, precision weapons employment, operation of sensors and optical equipment, etc. The USAF also wants T-X to exhibit high availability and mission-capability rates in order to reduce sustainment costs and allow for more flight hours with a smaller fleet.

In terms of maneuverability and performance, the USAF has opted to establish minimum requirements as well as target figures. Any aircraft which exceeds the minimum requirements will receive extra points in the competition. For example, the program requires entrants to execute sustained 6.5g turns for at least 140° at 15,000 feet; the objective is for aircraft to complete the same turn at 7.5+g. Entrants must bleed no more than 10% of their initial airspeed and 2,000ft of initial altitude over the course of the maneuver.

Airframe price and lifecycle costs are also considered, so an aircraft that exceeds the minimum performance requirements but costs significantly more as a result may not have an overall advantage. Nevertheless, the sustained g requirement turned out to be somewhat of an obstacle for a few of the T-X hopefuls; Northrop abandoned its plans to offer a BAE Hawk-based trainer as a result, and Textron AirLand’s Scorpion jet is also unable to compete because of the turn rate stipulations. Interestingly, General Dynamics’ break from Leonardo-Finmeccanica was initially assumed to be a result of the M-346’s inability to execute sustained 6.5g turns. However, Raytheon’s supplantment of General Dynamics suggests that the M-346 must be capable of executing the minimum required gs, although this may require alterations to the M-346’s airframe.

An M-346 in flight. General Dynamics was originally slated to offer a trainer based on the M-346, but it later backed out, leaving Raytheon to team with Leonardo-Finmeccanica instead.

An M-346 in flight. General Dynamics was originally slated to offer a trainer based on the M-346, but it later backed out, leaving Raytheon to team with Leonardo-Finmeccanica instead. Image by Gian Marco Anzellotti.

There was initially some uncertainty as to whether the Air Force would consider using T-X for other roles, principally the light attack role. Some analysts and policymakers contended that a T-X modified for light attack could undertake of the lower-end counterinsurgency operations currently handled by maintenance-intensive aircraft such as the F-16 and A-10. While an intriguing and not uncommon proposal, it appears that the USAF has decided to relegate T-X to the training role, at least until the trainer variant is finalized. Nevertheless, even if the USAF never employs its T-X aircraft in combat, it is likely that other nations who purchase T-X as an import may desire light attack or even air-to-air capabilities. While the basic T-X requirements have been revealed, the program has not formally begun, so none of the metrics are set in stone. If performance standards were to be reduced, some vendors such as Textron would likely re-enter their aircraft. However, at this point the USAF seems relatively committed to its performance goals, and with four 6.5g+ entries already on the table, there is little incentive to loosen them.

At the moment, four prime contractor teams are competing for the T-X contract: Raytheon, Lockheed Martin (LM), Boeing-Saab, and Northrop Grumman (NG). Two of the offerings, those of Raytheon and LM, are based on existing trainer aircraft already in service with other nations.  Boeing-Saab and NG’s offering are both clean-sheet designs, meaning the aircraft have been engineered from the ground up for the T-X program. Each approach has merits and potential drawbacks.

Modifying an existing aircraft has potential cost and risk benefits. Researching and developing a new aircraft can be a costly affair. Modern aircraft are quite complex and require a prodigious amount of engineering work to bring to fruition. Along the development path, unexpected issues usually crop up, and resolving them can put a program further behind schedule and over budget. Using an existing airframe allows the contractor to avoid these issues by selecting an already-proven design which needs minimal additional development to field. Not only are R&D costs reduced by the usage of a pre-existing blueprint, but maintenance and sustainment costs will likely be better managed as well. Since other nations already operate aircraft of the type, maintenance procedures are well documented and cost estimates can be made more accurately. Overall, avoiding a clean-sheet approach can help manage costs and keep the project on schedule, a critical consideration at a time when the USAF budget is tight and cost overruns in one sector could endanger the balance of the budget as a whole.

The main benefits of a clean-sheet design are customization and performance. No existing aircraft meets all the stipulations of the T-X program, so even Raytheon and LM’s designs will be modified slightly from the original airframe. The use of a clean-sheet design allows Boeing-Saab and NG to build an aircraft tailored exactly to the USAF’s specifications, which may result in a more effective aircraft. It also means that Boeing-Saab and NG can more easily adapt to evolving program requirements, as they are not locked into a design with set dimensions and componentry. Clean-sheet designs also avoid the need to bargain with an existing party; Raytheon and LM get to use other companies’ designs, but not without appropriate compensation. By investing in a clean-sheet design, Boeing-Saab and NG are not locked into agreements about work-sharing and are able to choose exactly where each part comes from. One benefit of this could be greater profits, but another important effect is that clean-sheet designs may seem more “American” to legislators and procurement officials, as their names are not tied to a foreign aircraft. Of course, Saab of the Boeing-Saab team is a Swedish company and will produce a portion of the aircraft, so this benefit may be lessened for Boeing.

Raytheon’s M-346 Master-derived entrant

An M-346 with weapons fitted to its wing pylons and a LITENING pod mounted to the centerline station.

An M-346 with weapons fitted to its wing pylons and a LITENING targeting pod mounted on the centerline station. Image by Milborneone. 

Raytheon has decided to put forth a T-X offering based on Leonardo-Finmeccanica’s M-346 Master. The M-346 is a twin-engine, single-tail aircraft. It is a modern but venerable selection, as the aircraft is operated by a number of US allies including Italy and Israel. On the international market, the Master’s selling point has been its advanced electronics and avionics; the M-346 features many of the avionic amenities found on fully-fledged strike fighters. While it does not possess a radar, it can synthetically generate radar symbology based on Link 16 datalink inputs, allowing for realtime alterations to training regimes. The M-346 has a digital fly-by-wire flight control system, which allows the aircraft’s computer to mimic flight characteristics of other aircraft.

The M-346 also has hardpoints which can be loaded with weapons for use in training or combat operations. Powered by two Honeywell F124-GA-200 turbofans producing around 6,000lb/ft of thrust each, the M-346 is capable of Mach 1.2 at high altitude. The Honeywell engines achieve these speeds without an afterburner, which helps to reduce engine complexity, fuel consumption, and maintenance costs. The dual-engine setup could be attractive because in the event one engine fails another is present for backup, which is especially appealing considering the aircraft will be operated by relatively inexperienced pilots in training flights. On the converse, dual-engine configurations are generally more expensive to operate and maintain, and single-engine planes (all other factors being relatively equal) tend to handle better.

It was initially unclear whether Leonardo-Finmeccanica could find a partner with which to offer the M-346 after General Dynamics backed out on a planned partnership. However, Raytheon stepped in and filled General Dynamics’ role. Raytheon has not been a major player in the defense aircraft realm, as opposed to the other three entrants, all of which currently have a major USAF program under their belts (Lockheed’s F-35, Boeing’s KC-46, and NG’s LRS-B). This has prompted some to note that if Raytheon were to win, each major US defense aerospace firm would have a large contract, referred to as “balancing the industrial base.” This would ensure that each of these companies has a future in aerospace, but if this were to be a main consideration, the final product could be inferior as a result. For its part, USAF procurement tends to claim (at least outwardly) that defense industrial base considerations are not major factors in contract decisions.

Lockheed offers T-50A based on Korean Aerospace Industries’ FA-50

An FA-50 taxis on the runway. Korean Aerospace Industries image.

An FA-50 taxis on the runway. Korean Aerospace Industries image.

Originally, Lockheed floated the idea of entering a clean-sheet design, but eventually decided against it. Instead, LM selected Korean Aerospace Industries’ T-50 Golden Eagle as its airframe. The T-50 is a single-engine, single-tail trainer. The T-50 exists in multiple variants; the T-50 is the basic trainer version, while the TA-50 and FA-50 are more advanced variants capable of employing weapons. LM’s T-X offering, dubbed the T-50A, is based on the FA-50 variant of the T-50. 

The choice of the FA-50 as a starting point is intriguing because the FA-50 is not only a trainer but a competent light fighter. The aircraft has a single afterburning General Electric F404-102 turbofan, good for 17,700 lb/ft of thrust with the afterburner. This allows the FA-50 to reach Mach 1.5 at altitude. As a result, the T-50A is almost as fast as the Mach 1.6 F-35 it is designed to train pilots for. Thrust without the afterburner is around 12,000 lb/ft, similar to the M-346. The FA-50 also features a pulse-doppler EL/M-2032 radar set, which has been fitted to fighters such as the Sea Harrier and the Mirage. In addition, the FA-50’s pylons can be loaded with weapons such as the AIM-120 AMRAAM, AGM-65 Maverick, various JDAMS, and advanced sensors including LITENING and Sniper targeting pods.

Needless to say, the T-50A will be faster and more “combat capable” than the M-346-based offering put forth by Raytheon. However, the goal of T-X is to procure a training aircraft, not a light strike fighter. It is unclear whether the T-50A’s amenities such as a fully-functional radar and afterburning engine will be viewed as beneficial or a costly and unnecessary. If the Air Force plans to later adapt T-X to provide light attack capabilities, then the T-50A would be attractive given its combat-ready avionics suite. On the contrary, if the USAF has no plans to ever employ T-X in dissimilar training or combat, some of its features may be wasted.

A T-50A during a high-speed taxi test. Lockheed Martin image.

A T-50A during a high-speed taxi test. Lockheed Martin image.

Indeed, when T-50 variants have competed against the M-346 in trainer-focused competitions, the M-346 has emerged victorious. Both Singapore and Israel chose the M-346 over the T-50. Countries which purchase T-50s tend to use them not only for training but for combat; Iraq, the Philippines, and Indonesia all operate a combat-capable version of the T-50 and plan to utilize the aircraft for light attack. Whether or not this phenomenon will play out in T-X remains to be seen.

Boeing-Saab’s clean sheet

Boeing's T-X prototype during an unveiling event. Note the twin tails.

Boeing’s T-X prototype during an unveiling event. Note the twin tails.

There is far less to be said about the two clean-sheet entries, as their specifications are not yet known. Thus, all that is possible at this point is speculation based on renderings and the slow trickle of information released by the respective contractors.

Boeing has partnered with Saab to design a twin-tail, single-engine aircraft. Both the F-22 and F-35 have twin tails, so Boeing likely chose the twin-tail configuration to emulate the handling characteristics of those aircraft as closely as possible. Boeing-Saab’s T-X entry will use a GE F404 engine, similarly to the T-50A. Boeing brings to the program its experience with the F/A-18E/F Super Hornet carrier-borne aircraft, while Saab has extensive experience building light single-engine fighters. The T-X entry reuses some systems from Saab’s Gripen fighter, according to Boeing officials. While the lion’s share of manufacturing will occur in the United States, some portions of the aircraft will be manufactured by Saab in Sweden. Boeing-Saab’s T-X entry will have two weapons pylons per wing. Whether or not it will have a radar and combat-ready avionics like the T-50A is unclear.

Northrop Grumman’s clean sheet

While Boeing-Saab has not revealed much about their aircraft, NG has been even more secretive. Apart from a few images taken during taxi tests and a small amount of information released to media, the program has been largely kept under wraps. NG teamed up with L3 and BAE Systems to build its prototype. Based on the images, it is clear that the NG’s T-X is somewhat similar to the T-38 Talon (also built by NG) it is designed to replace. Both have similar aerodynamic surfaces, including a single tail, and dual intakes. However, NG’s T-X is a single-engine aircraft, unlike the T-38, which had two engines. Like the T-50A and Boeing-Saab’s T-X, NG’s T-X  utilizes a GE F404 powerplant; Raytheon’s M-346-based offering is the only aircraft in the competition powered by dual fans. Information regarding possible weapons stations and avionics is not currently available.

Concluding remarks

At the moment, only two of the T-X entries can be effectively assessed, as critical information regarding the clean-sheet designs is missing. However, already a clear dichotomy exists between the afterburning, combat-ready T-50A and the training-oriented, maintenance-friendly M-346. Until program requirements are solidified by the USAF, it is hard to know where each aircraft’s selling point will lie, and how certain requirements will be weighted. Nevertheless, T-X is shaping up to be an interesting program with a large number of highly promising entries. This article will be updated to reflect any additional information, and more content related to T-X is almost certain considering the complex nature of the program and its relative infancy.

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