The Diverterless Supersonic Inlet (DSI) is a novel air inlet design principle used by modern fighter aircraft to control air flow into their engines. It is a three-dimensional bulge loss without surface layer partition. It consists of a “bump” and a forward-swept inlet cowl. Both work together to divert boundary layer airflow away from the aircraft’s engine. DSIs can be used to replace the intake ramp and inlet cone, which are more complex, heavy and expensive. The purpose of the intake of an aircraft is to supply the engine with a proper airflow during various flight conditions. Characteristics of a good intake design includes provision of high pressure recovery and low distortion.
According to experts, the DSI inlet has three main advantages over conventional inlets. First it adopts a “cone flow” wave rider design, which has a higher total pressure recovery. It improves the stealth performance of the aircraft. Secondly it reduces the drag on the windward side of the aircraft. Third is that no auxiliary intake and exhaust valves are designed. Thus reducing the weight of the aircraft by hundreds of kilograms. It grants the provision of carrying extra load during operations. Overall the DSI inlet has the characteristics of simple structure, light weight, low resistance and invisibility.
So far five modern aircraft designs have successfully integrated DSI. One is F-35 Joint Strike Fighter, and the others are the J-10, JF-17, J-20 and J-31 multi-role fighter aircraft.
Pakistan Air Force (PAF) is considering RD-93MA as an option for next block of JF-17 fighter jet. Russia’s United Engine Corporation (UEC)-Klimov is developing the engine. It has entered thermal chamber tests to confirm high-speed characteristics in simulated flight conditions. RD-93MA is an upgrade of the RD-93 engine which currently powers the JF-17 single engine fighter jets. With the successful completion of the thermal chamber test stage, it will be possible to proceed to flight design tests. Subsequently a set of tests in the TsIAM large thermal pressure chamber will be held as part of the experimental design work on the RD-93MA. The engine may enter fight test mode towards the end of the year. Thus the JF-17 Block III would enter flight tests with the RD-93MA engine sometime in 2021-22 at the earliest.
The reference to use in single-engine aircraft has given rise to speculation that the new engine is destined for the JF-17 fighter. Earlier reports said the RD-93MA engine will be directly sold to Pakistan. However, sources told us that a Chinese company is working on the contract to manufacture 100 such engines. The thrust of the RD-93MA is reportedly 9300 Kgf compared to 8300 kgf of the RD-93. RD-93 is the primary engine of Mig-29 jets and earlier versions of JF-17 Thunder jets. The RD-93MA engine has improved performance. In the first place it has increased thermodynamic parameters. Secondly an improved design of the fan and the hot part is provided. Further it features an upgraded automatic power-plant control system and emergency engine start mode. To Summarize it is a significant bump-up in power which will help the JF-17 to carry more armaments and fly at a higher speed.