if the props on the wings can be replaced with jets then this can add to the speed and maybe more safety for crew and equipment. but then again I dont know how well jet engines on the either wing can compete with the propeller engines in terms of feul economy.
so endurence vs speed might be a consideration.
On any single rotor design, torque from the rotor
MUST be countered. We do that via the popular method of a long tail, either with a prop or with the NOTAR design...
NOTAR - Wikipedia, the free encyclopedia
NOTAR is the name of a helicopter anti-torque system which replaces the use of a tail rotor. Developed by McDonnell Douglas Helicopter Systems, the name is an acronym derived from the phrase NO TAil Rotor. The system uses a fan inside the tailboom to build a high volume of low-pressure air, which exits through two slots and creates a boundary layer flow of air along the tailboom utilizing the Coandă effect. The boundary layer changes the direction of airflow around the tailboom, creating thrust opposite the motion imparted to the fuselage by the torque effect of the main rotor. Directional yaw control is gained through a vented, rotating drum at the end of the tailboom, called the direct jet thruster.
This X-3 seems to want to have as best of all worlds with the two wing props.
First...Angling the main rotor and thereby redirecting the downward thrust off the vertical axis is a terribly inefficient way to move the mass in any direction. Most of the power is reserved to keep the helo airborne and only a fraction of that downward thrust is used to displace the aircraft. But that is how today's helos operate.
Second...The American V-22 removed that inefficiency by completely tilting the rotors' thrust but only
AFTER the aircraft has achieved full aerodynamic exploitation via the wings and other flight control surfaces.
It is clear then the advantages and disadvantages from both.
The X-3 is an attempt to solve these problems by having the wing props doing the job of countering torque created by the main rotors and to provide horizontal thrust for forward motion. I have no doubt that that main rotor can be used to displace the aircraft as well but am confident that it will be for very slow motion as in during hovering mode to land.
The X-3's wing props, from appearances so far, are not so much 'engines' as they are thrust providers via shafts from the main engine. In other words, there are no engines in the wings. For the American V-22 Osprey, there are real engines and there are connecting shafts between them in the event one engine is lost the other engine can still provide sufficient power to sustain flight.
The European Tiltrotor design is intended to 'improve' the V-22's engine placements and its associated mechanical issues...
European Tiltrotor Eurotilt helicopter - development history, photos, technical data
Erica was second-generation tiltrotor, incorporating improvements over BA609 and V-22. Engines mounted inboard, underwing, driving connecting shafts to proprotors at wingtips.
So as we can see, the V-22's engines are at the wing tips and they are connected to each other via long driveshafts. The European version moved the engines inward and drive the wing tips' props via long driveshafts.
The X-3's wing tips' props are probably no different from the European tiltrotor design in that the single main engine is connected to the wingtips props via long driveshafts. They are needed in those places to maximize their ability to counter the torque created by the main rotor. One prop create more thrust than the other. Keep in mind that the main engine is a turbine or commonly known as a 'jet' engine itself.