The hybrid propulsion of the Valkyrie, the UGV of SASCorp

Javier de Juan Gutirrez, Director of Terrestrial Systems of SASCorp reveals to us in this interview the characteristics of the propulsion system chosen for the revolutionary UGV designed by SASCorp. Let’s remember that Valkyrie It was one of the sensations of the last edition of the FEINDEF fair and we recently detailed the characteristics of the amphibious variant.

What is the starting point of the UGV design?

At SASCorp, the development of a high-performance unmanned ground vehicle (UGV) has been proposed from scratch, which allows us to fully exploit the intrinsic capabilities of unmanned vehicles. We have not started from an existing platform, coming from other uses and with other conditions that limit the design of a military UGV. In our case, the powertrain, suspension and vehicle architecture are strongly interrelated in their design and the solutions that provide the best performance, operability and cost have been adopted.

The powertrain has been developed with purely technical criteria, taking the solutions that provide the vehicle with better performance, being realistic with the present and future of propulsion and power generation systems.

Within the revolutionary approach of the UGV in which you are working, the propulsion in turn is very advanced. Can you describe the motor group or power unit?

It is a high-performance turbodiesel engine with a power of 350 hp that works as an electric generator within the hybrid propulsion system. Said system will consist of a backup battery that will allow a certain degree of 100% electric mobility of 3 km. but whose main function is to support the electrical system in the face of high power demands. The vehicle has been equipped with 6 electric motor-wheel assemblies that allow totally independent 6×6 traction. The vehicle also has regenerative braking that significantly reduces the use of conventional brakes.

What are the advantages of a hybrid plant like this?

From an energy point of view, it allows the combustion engine to always work at optimum speed. The powertrain has been designed together with the suspension/transmission system, thus being able to offer exceptional performance. It is a system conceived from scratch to make the most of the design peculiarities of an unmanned platform.

What characterizes the selected heat engine?

The choice is an accumulation of technical and operational commitments, on the one hand the availability of fuel typical for military use, on the other technical issues such as reliability, maintenance, engine torque or acoustic signature profoundly mark the choice of engine. All this in addition to seeking a good weight-power ratio.

The solution adopted provides the solidity of combustion engines with a long history behind them and advanced technology that ensures their reliability and performance.

Internal architecture of the UGV showing one of the motor-wheel assemblies (SASCorp)

What benefits in terms of range or speed can you achieve with your hybrid propulsion?

The maximum speed is 40 km/h as all-terrain capabilities and overcoming slopes prevail. The benefits vary a lot depending on the configuration and use, but the autonomy in normal operation (hybrid) will be around 8-10 hours. In our case, the adoption of the hybrid propulsion architecture is aimed at the mechanical simplicity of the vehicle and the benefits obtained by an electrical system. The degree of traction control that can be achieved with an electrical architecture like the one used in our UGV is far beyond what is possible with traditional mechanical transmissions. The independence of each wheel is total with respect to the rest (each wheel can apply more or less torque, brake independently or even turn in the opposite direction to the rest) this allows extraordinary maneuverability and overcoming obstacles.

The UGV is expected to be able to fuel that propulsion with hydrogen. What are the advantages of using it as fuel? Will it involve any design change?

Yes, it is foreseen since hydrogen will have a great presence in the near future, combustion engines continue to evolve and they still have a long life ahead of them. The changes will not be noticeable in terms of vehicle design and architecture.

Hydrogen is capable of providing equivalent and even higher energy densities than hydrocarbons, values ​​that are 50 times higher than those offered by electric batteries. Only the energy densities of hydrocarbons (or their substitutes) and hydrogen can realistically guarantee the continuity of transport, aviation or military use.

In the current scenario of rising hydrocarbon prices, a hybrid system seems like a logical bet. What advantages can the user obtain in terms of logistics and support?

I refer to the previous answers, the reasons are technical and benefits. The best solution has been sought from the technical and operational point of view. The vehicle will not require special recharging infrastructures, will not require charging times that make its use unfeasible or autonomy that limits its use. Using a turbo diesel engine as a base guarantees the availability of fuel without the need for a specific supply different from the rest of military vehicles.

Will there be different engines for Tellus and Valkyrie? Is there a possibility to adapt the propulsion group to the needs of the client?

The powertrain is designed according to the requirements of the vehicle and no variations are foreseen, except for the fuel as mentioned above.

The amphibious version is equipped with hydrojets. Will it be necessary to modify the propulsion group?

The design is conceived from the outset to power the amphibious version, no further modification is necessary.

Different applications are proposed for the UGV, which will also have multiple sensors. What is the capacity of the electrical generation system? Is it possible to use it to support the needs of the troops?

The system has sufficient capacity to provide energy to other uses, whether electrical, mechanical or hydraulic, according to the different requirements of the clients. (Jos M Navarro Garcia)

Cover photo: Valkyrie fitted with a 30mm remote tower. (SASCorp)

Javier de Juan Gutirrez (SASCorp)

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