#4. The Joby tilting front propeller location is being standardized as is also used by Archer, Vertical Aerospace, Supernal and now Wisk. With this configuration, the propulsion system suffers from a major disadvantage in transition, namely when the power requirements are at maximum. At the beginning of the transition, the wings are blown from top to bottom and an increased pressure appears on their upper surface instead of creating a depression (as is desirable for an efficient wing). Consequently, the demand for power increases even more. They still fly due to the excess power for which they are designed, but the flight is inefficient in transition. Moreover, the number of tilting mechanisms is big, increasing the weight, complexity, and cost of the vehicle. There are a number of more efficient configurations and for sure the Joby solution will be not the dominant technology of the future.
Hey Liviu - thank you for your insightful comment.
Could you quantify how much of an inefficiency this is? And I am wondering, since transition takes ~30 seconds, how much of an impact this is to battery requirements?
In Joby case, the transition is made by tilting the rotors from 0° (vertical flow) to 90° (horizontal flow). I am finding it is hard to calculate the power required for this transition, taking into account also the negative induced lift on the upper surface. Maybe is easier to use CFD. The transition is very important because it consumes more power than take-off since it is creating lift (hasn't reached the minimum velocity for the lift requirement) for balancing weight and also needs to provide thrust for forward motion. So, to this highest power requirement, supplementary power is required to compensate for the negative induced lift. After me the transition is much longer than take-off (probably at least 100 s) because the horizontal component of the thrust force is very small at the beginning of the transition process.
Most current solutions (Joby, Archer, Vertical Aerospace, Supernal, Wisk) are based on the design of the classic separation of the aircraft body and the propulsion system. My activity aims to highlight the benefits that can be achieved by the aircraft having a distributed propulsion system synergic integrated with the aircraft body. With this synergic approach of the propulsion system and the configuration of the aircraft, new possibilities appear to improve the performance of the aircraft that are not otherwise possible. By introducing new variants of integrated propulsion systems, very low specific traction levels can be achieved, thus paving the way for high efficiency associated with low noise levels. I already have two examples of my proposals already published on
These VTOL vehicles tilt the entire propulsion system around the wings to produce high lift (augmentation) effects even in static conditions, using a single redundant actuator/vehicle.
I have also worked on other solutions which can be discussed with the interested entities.
All these new designs offer a number of advantages compared with the current developments:
-Reduced complexity and cost-efficient even offer a high redundancy level
-Multi-mission capability because the same aircraft can operate as VTOL, STOL or CTOL
-High efficiency in hover, and transition due to blown wings
-High efficiency in forward flight due to blown wings and propeller deactivation
-Reduced power requirement in take-off and transition
-Scalability of the design from drones to large aircraft
-Can be developed using an existent airframe and this can reduce the development costs with around 50%
Also, it is presented another imaginable variant having dynamic charging, in which the aircraft retains its full freedom of flight. In principle, a dynamic charging solution allows power to be continuously supplied to the vehicle from an external source, thus enabling a significant reduction of the on-board battery size and, at the same time, reducing virtually to zero the time the vehicle needs to stop for the recharging operations and the related range anxiety.
In Joby case, the transition is made by tilting the rotors from 0° (vertical flow) to 90° (horizontal flow). I am finding it is hard to calculate the power required for this transition, taking into account also the negative induced lift on the upper surface. Maybe is easier to use CFD. The transition is very important because it consumes more power than take-off since it is creating lift (hasn't reached the minimum velocity for the lift requirement) for balancing weight and also needs to provide thrust for forward motion. So, to this highest power requirement, supplementary power is required to compensate for the negative induced lift. After me the transition is much longer than take-off (probably at least 100 s) because the horizontal component of the thrust force is very small at the beginning of the transition process.
#4. The Joby tilting front propeller location is being standardized as is also used by Archer, Vertical Aerospace, Supernal and now Wisk. With this configuration, the propulsion system suffers from a major disadvantage in transition, namely when the power requirements are at maximum. At the beginning of the transition, the wings are blown from top to bottom and an increased pressure appears on their upper surface instead of creating a depression (as is desirable for an efficient wing). Consequently, the demand for power increases even more. They still fly due to the excess power for which they are designed, but the flight is inefficient in transition. Moreover, the number of tilting mechanisms is big, increasing the weight, complexity, and cost of the vehicle. There are a number of more efficient configurations and for sure the Joby solution will be not the dominant technology of the future.
Hey Liviu - thank you for your insightful comment.
Could you quantify how much of an inefficiency this is? And I am wondering, since transition takes ~30 seconds, how much of an impact this is to battery requirements?
In Joby case, the transition is made by tilting the rotors from 0° (vertical flow) to 90° (horizontal flow). I am finding it is hard to calculate the power required for this transition, taking into account also the negative induced lift on the upper surface. Maybe is easier to use CFD. The transition is very important because it consumes more power than take-off since it is creating lift (hasn't reached the minimum velocity for the lift requirement) for balancing weight and also needs to provide thrust for forward motion. So, to this highest power requirement, supplementary power is required to compensate for the negative induced lift. After me the transition is much longer than take-off (probably at least 100 s) because the horizontal component of the thrust force is very small at the beginning of the transition process.
Liviu - what do you think would be the solution here? What is the most efficient design configuration for transition?
Most current solutions (Joby, Archer, Vertical Aerospace, Supernal, Wisk) are based on the design of the classic separation of the aircraft body and the propulsion system. My activity aims to highlight the benefits that can be achieved by the aircraft having a distributed propulsion system synergic integrated with the aircraft body. With this synergic approach of the propulsion system and the configuration of the aircraft, new possibilities appear to improve the performance of the aircraft that are not otherwise possible. By introducing new variants of integrated propulsion systems, very low specific traction levels can be achieved, thus paving the way for high efficiency associated with low noise levels. I already have two examples of my proposals already published on
https://evtol.news/skynet-project-genesys-x-1
https://evtol.news/skynet-project-ueva
These VTOL vehicles tilt the entire propulsion system around the wings to produce high lift (augmentation) effects even in static conditions, using a single redundant actuator/vehicle.
I have also worked on other solutions which can be discussed with the interested entities.
All these new designs offer a number of advantages compared with the current developments:
-Reduced complexity and cost-efficient even offer a high redundancy level
-Multi-mission capability because the same aircraft can operate as VTOL, STOL or CTOL
-High efficiency in hover, and transition due to blown wings
-High efficiency in forward flight due to blown wings and propeller deactivation
-Reduced power requirement in take-off and transition
-Scalability of the design from drones to large aircraft
-Can be developed using an existent airframe and this can reduce the development costs with around 50%
Interesting concept! I would love to understand more how the tilting mechanism works. Is it essentially a tilt-wing albeit in reverse i.e. tilt-body?
Is there a video animation for this?
It can see a detailed presentation, describing each sequence of flight for Genesys X-2: https://www.linkedin.com/pulse/cost-effective-ultra-efficient-vtol-aircraft-genesys-x-2-liviu-giurca/
Also, it is presented another imaginable variant having dynamic charging, in which the aircraft retains its full freedom of flight. In principle, a dynamic charging solution allows power to be continuously supplied to the vehicle from an external source, thus enabling a significant reduction of the on-board battery size and, at the same time, reducing virtually to zero the time the vehicle needs to stop for the recharging operations and the related range anxiety.
In Joby case, the transition is made by tilting the rotors from 0° (vertical flow) to 90° (horizontal flow). I am finding it is hard to calculate the power required for this transition, taking into account also the negative induced lift on the upper surface. Maybe is easier to use CFD. The transition is very important because it consumes more power than take-off since it is creating lift (hasn't reached the minimum velocity for the lift requirement) for balancing weight and also needs to provide thrust for forward motion. So, to this highest power requirement, supplementary power is required to compensate for the negative induced lift. After me the transition is much longer than take-off (probably at least 100 s) because the horizontal component of the thrust force is very small at the beginning of the transition process.