Bell has just completed a test of a hybrid propulsion system designed for Darpa’s Sprint X aircraft concept. It ensures vertical takeoff and landing using rotors. When cruising, the propellers fold to make way for jet propulsion.
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Il porteporte the code name Sprint X and this programaéronefaéronef military will have an astonishing technology allowing it to take off and land vertically with propellers, to then evolve into high-speed cruise vitessevitesse with jet propulsion. The concept falls into the category of HSVTOL, for high-speed vertical take-off and landing aircraft. After a concept phase during which four aircraft manufacturers were in competition, the project initiated by Darpa is led by Bell for the US research laboratory. AirAir Strength. The concept is supposed to make it possible to obtain high speed, great autonomy, maneuverability and stealthstealth.
The principle is that of the rotorcraft, with a tilting rotor which goes from vertical for takeoff and landing and to horizontal for cruising. It is the same concept as that of the Bell Boeing V-22 Osprey, but with a major innovation. Instead of simply rotating the rotor nacelle, when it gains speed, the Spring X will stop the propeller traction. The blades are positioned in a “flag”, slice facing the masse d’airmasse d’air, to immobilize them. They then fold into the nacelles to reduce drag and therefore increase speed. Only the reactor’s propulsion will remain to reach a speed greater than 830 km/h. The device could fly at an altitude of more than 9,000 meters and its autonomy could reach 370 kilometers, according to Darpa specifications.
The aircraft will be able to take off and land anywhere, including on a barge at sea, as shown in an illustrative image published by Bell. This is not a small size, as its compartment will need to be large enough to hold a small vehicle and carry a payload of 2.3 tonnes.
The ground test shows the operation of the hybrid engine and the propeller folding system to make way for jet propulsion.© Bell
Reduce drag by folding propellers
Due to its speed, its stealth and its vertical landing and takeoff system, the missions of this aircraft would be intended for the rapid deposition of special forces near the combat zone, or to be used for relief operations. in the event of a disaster in areas that are difficult to access.
The Spring X could be available as a drone or be piloted by a crew. It would also have stealth capabilities. Long kept secret, Bell now communicates on its progress. The manufacturer has just released a video showing a ground test of its engine with its system hybridhybrid. The test bench runs on rails and we can see in turboprop mode, the turbine turning the propellers to gain speed. When this is sufficient, the rotor stops and the propeller locks. The blades then position themselves in a feathered position, then stop and fold backwards and the reactor delivers all its power to maintain its cruising speed. Testing took place at Holloman Air Force Base in New Mexico. In terms of design, for the moment, only synthetic images are available. They show an aircraft that looks like a drone with two beamsbeams acting as wings and supports for the rotors at the tips of the wings. At the rear, we find an elevator and a tailplanetailplane V shape to reduce drag.
Darpa wants an X-Plane VTOL capable of flying fast
Darpa is putting four aircraft manufacturers in competition to create an X-Plane VTOL capable of cruising at high speed. The first concepts have just been revealed.
Article from Sylvain BigetSylvain Bigetpublished on November 16, 2023
The American army’s research and development agency, Darpa, wants to develop an X-Plane capable of both cruising at high speeds and landing and taking off vertically. This project is named after Speed and Runway Independent Technologies (Sprint). Four companies will be put into competition to offer prototypes of demonstratorsdemonstrators X-Plane with this VTOL capability. In terms of specifications, the aircraft must be able to reach a top speed of at least 740 km/h for altitudes between 4,500 and 9,000 meters. It must be able to carry a payload of at least 454 kilos. In terms of autonomy, Darpa requires a range of 370 kilometers and a durationduration flight time of at least 90 minutes.
Concepts already revealed
The device will also need to be versatile to meet a wide range of missions. The plane must also be able to land and take off on surfaces not intended for this purpose, such as fields, parking lots or roads. The successful applicants are Aurora, Bell Textron, Northrop Grumman Aeronautic Systems and Piasecki Aircraft Corporation. The aircraft manufacturer that wins the call for tenders should fly its prototype from 2027, so that it will be operational from 2028.
For now, AuroraAurora has already revealed its X-Plane concept. It is a mixed wing with rotors placed under the cabin for the takeoff and landing phases. Once in cruise, they are covered by covers in order to increase the portanceportance. Bell Textron uses the proven principle of the V-22 Osprey, with a jet engine in the cruise phase. The rotors are then folded to reduce drag. The other two aircraft manufacturers have not yet revealed their concepts.
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