The J-27 Ignis represents a meticulous combination of features that allow both hovering flight like a helicopter, as well as highly efficient forward flight at high sub- (and super) sonic speeds. Since the latter practically contributes to nearly 100% of the distance traveled, it is specifically designed around this point, while minimizing trade-offs.
It is designed with an estimated maximum take-off weight of 9.000kg (18,500lbs), a wingspan of 8.5m (27ft), and a length of 14.5m (47ft). It accommodates 4-6 passengers alongside a single pilot. Powered by an augmented power plant (hybrid electric-hydrogen), it achieves both hovering capabilities and efficient forward flight. With a cruising altitude of 8.500m (27,000ft) at Mach 0.7, the aircraft promises a carbon-emission-free range of 1,000 km (640nmi) (additional reserves left).
To achieve these feats, an aircraft had to be designed from zero. -Tailored precisely to its deeds.
In order to comply with the highest aerodynamic efficiency during the desired flight regime, the design of the airframe resulted in a blended wing with a Delta configuration and a lifting body, acting much like a Canard. The entire craft’s shape is based on an exclusively developed laminar flow airfoil, which reduces friction drag significantly. The tail was omitted entirely to save even more on friction drag. The prominent downward angled winglets play a pivotal role in the entire design and are integral in ensuring control and efficiency in all phases of flight.
In general, the design of the J-27 aims at the greatest possible reduction of otherwise essential outer surface area and dead weight (e.g. large wings, large control surfaces, landing gear, sub-optimal wing profiles, etc.) by utilizing what otherwise would be considered a full trade-off (e.g. using parts of the main engines’ thrust reversal as bi-axial thrust vectoring during forward flight to increase control authority and safety while minimizing, or eliminating, regular control surfaces for that task). Furthermore, the entire design is optimized for the highest possible internal volume to outer surface area, which is of great importance for efficiently carrying large amounts of Hydrogen.
Two (adaptive) hybrid main engines provide thrust during forward flight. For hovering, their thrust is redirected down 90° by changing the outlet geometry and contribute 2/3 of the total required lift force. A fully electric fan hidden in the front fuselage takes over with the rest, providing lift ahead of the centre of gravity. Two small impellers within the wings provide stability and control.
The envisioned main engines’ power output can vary and adapt to each phase of flight. During hovering flight, which requires tremendous amounts of power compared to forward flight, the batteries on board can safely contribute only a fraction of the power needed. The rest is taken over by the combustion of hydrogen, which offers ‘’raw power’’. During forward flight, propulsion is achieved mainly electric, while the combustion of hydrogen is an assistant force, lowering the discharge ratio of the batteries just bellow 1C.
This hybrid coupling enables hovering flight, lowers the load on the batteries, simplifies battery-cooling systems, extends battery life (maximum cycle count), and operational efficiency during flight. This setup fundamentally enables the creation of this craft with the technology at hand today, as this is written. No new physics required.
The airframe is designed such that it can adapt to advancements in either field, making for an easy fully electric adaptation, should the day come where batteries become a first choice.