Turkey Rolls Out A Mock-Up Of Its Indigenous Stealth Fighter To An Uncertain Future

Souring relations with the United States could have a serious impact on the Turkish fighter program, including its choice of engines.

TAI

Turkish Aerospace Industries has unveiled a full-size mock-up of the TF-X fighter jet that it is developing for the Turkish Air Force and says that it hopes to have a prototype flying within six years. This news comes amid the increasingly likely prospect that the United States will eject Turkey from the F-35 Joint Strike Fighter Program over its purchase of Russian-made S-400 air defense systems, which could have impacts on the indigenous fighter project, especially when it comes to what engines will power the jets.

TAI unveiled the model, which is rumored to have cost the company almost $2.25 million itself, at the 2019 Paris Air Show, which opened its doors on June 17, 2019. The firm's President and CEO Temel Kotil said that the goal is to have built a prototype by 2023 and achieve a first flight with the aircraft in 2025. 

The Turkish government first announced the TF-X program, also known as the National Combat Aircraft, which abbreviated MMU in Turkish, in 2010. TAI won the contract to develop the aircraft, in 2015. The Turkish Air Force plans to eventually replace the bulk of its American-made Lockheed Martin F-16C/D Viper fighter jets with this indigenous design and hoping to have the first examples enter service as early as 2028.

Since 2015, TAI has proposed at least three different configurations, including two single-engine variants and a twin-engine type. The mock-up is of the twin-engine concept, which is the one the company had settled on previously. 

The overall design shows some very broad similarities to the Lockheed Martin's F-22 Raptor and F-35 stealth fighters. The twin-engine design is also reminiscent to some degree of China's latest FC-31 prototype and South Korea's KF-X design.

Whether TF-X has comparable stealth capabilities to a fighter such as the F-22 or F-35 remains to be seen. For instance, the mockup, as had been the case with previous concept art, continues to show exposed exhaust nozzles for the fighter's two engines. The model doesn't give any hints about whether the aircraft will bury the engines deep inside the fuselage behind snaking s-shaped inlets, another important design feature for stealthy aircraft. Internal baffles are another option, but would not be as effective. 

TAI is, at least for the moment, responsible for the production of Joint Strike Fighter fuselage sections, which Kotil said gives the company important industrial capacity and production experience to support the TF-X program. However, more goes into stealth than just shape. Applying special radar-absorbing coatings, crafting specialized structures, and eliminating seams are among the other factors the Turkish aerospace firm will have to contend with.

TAI

The TF-X mockup at the 2019 Paris Air Show.

With an overall length of 60 feet and a wingspan of 39 feet, the TF-X is smaller dimensionally than an F-22, but slightly larger than the F-35. Previous concept art shows that TAI expects the fighter jets to have both cheek and ventral internal weapons bays like the Raptor. TAI also says the fighters will have supersonic speeds of up to Mach 2, though it's not clear if this means they will have the ability to fly at that speed for a sustained period, or supercruise, like the F-22. 

But whatever its final specifications might be, the TF-X program has taken on new emphasis in recent months as the U.S. government works to boot Turkey from the F-35 program over Ankara's purchase of Russian-made S-400 surface-to-air missile systems. The United States, in particular, has voiced concerns that this could result in Russia gaining important insight into the Joint Strike Fighter's capabilities and stealthy signature, issues you can read about in more detail here and here. Turkish representatives already found themselves locked out of the annual F-35 CEO Roundtable on June 12, 2019. 

Coupled with worsening U.S.-Turkish relations in general, this dispute could easily have second-order impacts on TF-X, especially when it comes to the engines. In October 2018, TAI selected General Electric's (GE) F110 family of afterburning turbofans – specifically the F110-GE-129 or F110-GE-132 – to power the future indigenous fighters. The -129 has a maximum thrust rating of 29,500 pounds, while the -132 offers up to 32,000 pounds of thrust, according to GE.

This made good sense since Turkey's TUSAŞ Engine Industries (TEI) already assembles F110s under license and the -100 and -129 variants power Turkey's Block 30/40 and Block 50 F-16C/Ds, respectively. This could help simplify maintenance and logistics demands, as well as ensure work for domestic industrial enterprises. The problem here is whether this relationship will necessarily be able to continue in the coming years.

TEI

TEI employees work on an F110 engine.

Though the Pentagon has no plans at present to censure the Turkish government outside of the F-35 program, Congress could seek to sanction Turkey under the Countering America's Adversaries Through Sanctions Act, or CAASTA. This, in turn, could make it difficult for American companies to do defense-related work in Turkey. American lawmakers could also simply seek to block any cooperation between U.S. firms and Turkey over the TF-X program. 

Legislators already asked the Pentagon to assess the impacts of Turkey's participation in five other weapon system programs beyond the F-35 in the final version of the annual defense policy bill for the 2019 Fiscal Year, also known as the National Defense Authorization Act. President Donald Trump signed that into law in August 2018. So far, there has been no change in the execution of any of these programs, including Turkey's local assembly of Sikorsky S-70i Black Hawk helicopters, which will be known as T70s.

Lockheed Martin

A prototype T70 utility helicopter for Turkey.

At the same time, cutting off Turkey from the F110 completely would be a huge policy shift that would effectively ground the Turkish Air Force's F-16s and could potentially have wider-reaching ramifications. Other countries looking to buy American jets or fighters with American engines could be more inclined to look elsewhere, as a result. Congress could seek a more limited and politically palatable approach that preserves cooperation over the F-16, but blocks any new engine-related transfers to Turkey specifically for TF-X. 

Turkish authorities would have limited alternatives readily available if this were to happen. In March 2019, it emerged that Rolls-Royce, which lost out to GE to build the engines for Turkey's fighter jet, had been working to further limit its cooperation in the program. This was linked to disputes between Turkish authorities and Rolls-Royce over the transfer of sensitive technology and intellectual property rights. 

This has also raised questions about the continued participation of U.K.'s BAE Systems in the TF-X program. In 2017, BAE signed a memorandum of understanding with TAI to provide engineering assistance for TF-X. BAE is leading the development of the U.K.'s own future stealth fighter, known as Tempest.

TAI could possibly turn to Russia for jet engines. The Kremlin has already pitched the idea of Turkey joining its Su-57 advanced combat jet effort if find itself excluded from the F-35 program. In 2018, Defense News reported that the Russians had previously offered to provide engines for the TF-X. The most recent models of Russia's Saturn AL-31 family are in the same general thrust classes of the F110-GE-129 and -132, though there have been questions about their overall reliability in the past. Saturn is in the process of developing an improved "Product 30" engine for the Su-57 specifically. Picking a Russian engine could potentially prompt Turkey's critics in Congress and elsewhere to call for even more sanctions against the country, too.

NPO Saturn

A briefing slide from Saturn and its partners showing the progression of the AL-31/AL-41F design leading to the Product 30 engine at the far right.

Engine-making TEI says they also have a plan to develop an indigenous engine for TF-X, but as of 2018, the company had laid out a 20-year roadmap for this development, according to Defense News. Even if that schedule proceeded uninterrupted, this would mean that series production would only begin around 2038, nearly a decade after the Turkish Air Force expects to begin taking large deliveries of TF-Xs. 

The Turkish Air Force is of the opinion that, whatever happens, it will need to begin replacing its F-16C/Ds in the 2030s. At present, Turkey has around 245 Block 30, 40, and 50 Vipers in total.

Turkish Armed Forces

A Turkish Air Force F-16C Viper.

There's also just the matter of whether Turkey will be able to afford to keep the TF-X program on schedule. As of 2018, the Turkish government had invested more than $1 billion into the development of the fighter jet as part of an incentive-based system. Historically, stealth fighter development programs have taken decades and 10s of billions of dollars to reach fruition. This is to say nothing of the costs associated with actually acquiring significant numbers of the jets or operating and maintaining them.

TAI's first flight timeline for its advanced combat aircraft is extremely ambitious in of itself. Even if the TF-X is a less advanced design than something such as the F-35, developing anything approaching a 5th generation fighter would still be costly and challenging.

In the meantime, Turkey is still betting very heavily on the TF-X to succeed, both in order to boost the capability of its Air Force and to help drive continued expansion of its domestic aerospace and defense industries. But it increasingly looks like TAI and the Turkish Air Force will be facing significant and increasing hurdles to turning the domestic fighter jet program into a reality.

TAI

TAI President and CEO Temel Kotil stands in front of the TF-X model at the 2019 Paris Air Show.

Contact the author: joe@thedrive.com