Photos showing Russia’s new stealth hunter have surfaced on the Internet.
The single-engine fighter, which the manufacturer Sukhoi calls “Checkmate”, is due to make its debut next week at the MAKS air show at Ramenskoye airfield in Moscow Oblast.
In the earliest pictures, Checkmate is covered with a tarpaulin. On photos that appeared on Sunday the tarpaulin is gone. What’s underneath could be a non-flying mock-up. Or it could be an airworthy prototype.
In any case, we can now try to evaluate Checkmate’s design.
At first glance, the Checkmate obviously has little observable features, including a chiseled nose and fuselage, V-shaped tail surfaces, and internal weapon bays – all of which help scatter radar energy rather than reflect it directly.
Perhaps most notably, the chin inlet has a noticeable underbite.
This underbite speaks for itself. A chin inlet – like the American F-16, European Typhoon, and Chinese J-10 – directs air directly to the turbine and can improve performance at high angles of attack compared to aircraft with complex side inlets.
But there is a downside. A chin inlet might require various gates and gaps to slow supersonic air to subsonic speed. Jet engines cannot process incoming supersonic air.
At the same time, a chin inlet typically does not offer designers many options for curving the inlet duct to obscure the turbine face. This means that enemy radars staring head-on at the hunter could have a direct view of the hunter’s most reflective element.
Chin inlets often require various weight-increasing tweaks to solve the supersonic airflow problem. They also imply a large frontal radar signature – an obvious problem when an aircraft’s designers aim for camouflage.
However, the Eurofighter consortium reportedly found a way to meander the Typhoon’s inlet to obscure the turbine. And Lockheed Martin refined a new inlet design in the 1990s – a so-called “divertless supersonic inlet” or DSI – which includes carefully placed bumps and bulges as well as the distinctive underbite.
The shape and underbite on a DSI accomplish two things. They slow down the incoming air and cover the turbine. As a bonus, a DSI is mechanically simple, so it can cut costs when compared to more complicated inlet designs like those of the American F-15 and Russian Su-27.
The greatest danger of a DSI is that it is likely to limit a jet’s top speed to less than Mach 2, while complex side inlets can create top speeds exceed Do two.
So if you’re looking for an affordable, agile fighter, this one Likewise Has few observable properties and you don’t mind sacrificing some speed, a DSI chin retainer is a smart approach. It should therefore come as no surprise that Checkmate appears to include this type of admission.
After all, Sukhoi’s goal is apparently to develop a stealth hunter that foreign customers can afford. The Russian Air Force may also want to purchase Checkmates to complement their larger, more understated, and likely very expensive Su-57s.
Even so, Checkmate may not be ready to fly – especially if the thing appearing on MAKS is more of a mock-up than a working demonstrator. Most new fighter aircraft designs never go into production due to development issues or a lack of paying customers.
Only time will tell whether Checkmate beats the odds … and actually goes into production.