Helicopter expert Daniel Newman, Chief Technical Officer of Honeywell’s Advanced Air Mobility Division, on the potential Blade Twist Control of the rotors:

“… As far as benefit, it could be substantial. As the airfoil sections of rotor blades experience such a wide variety of flow conditions – over a long timescale between flight conditions (e.g., hover vs. cruise), and over a shorter timescale during each rotation in edgewise flight (advancing vs. retreating blades) – they are perhaps the ideal component for geometry variation to maximize performance across all conditions.”

“Variation (also reconfiguration, morphing and adaptation) by its very nature is the ideal means to improve capability under varying conditions, as it avoids the compromise of balancing the performance between conditions and allows optimizing for each.”

“The ability to parse requirements in time, and solve them in series as opposed to simultaneously, is an incredibly powerful approach to design.”

“You write that twist control has immediate effect on thrust, as opposed to the delayed effect of RPM control. This presumes a means of changing twist very rapidly, far more rapidly than proposed approaches such as shape memory alloys and circulation control.  This benefit is only available if a means of twist change is proven with a sufficiently high bandwidth (rate). And note that if such a high rate capability were available, it might enable cyclic rotor control as well.”

Managing the blade AR

Instead of the common elliptic blade-planform

VTOL / Helicopter rotors may require blades with higher aspect ratio.

Skeleton grid must assume elongated shape.

Challenge:

excessive flexibility of the blade due to relative narrow holding area at the foot, and blade-CG moving away from the base;

possible vibration of the blade body;

undesired deformation of the skeleton grid (masts) may work against the effect of the useful twisting moment fed into the grid base as the means of blade-twist control.

Solution:

modification of the reinforced TTMØ element (see in bright color);

holding area of blades becomes less concentrated, thus flexibility gets reduced;

controlling moment is fed into the grid not at the base, but closer to the location of the blade-CG (inertia-born bending moments reduce);

movements (deformation/vibration) of the masts are kept in check by the modified TTMØ element.

Traditional propellers inherently are and will remain the causes of typical eVTOL issues like

noise,

vertical lifting performance versus top cruising speed, and

efficiency.

By adding more blade-sophistication to propellers those issues can greatly be alleviated. Concept is ready for prototyping. Working name is Stallfree technology.

Propeller-Efficiency is Key to Feasibility of New VTOL/eVTOL Concepts

It is impossible to stick to design speed during a whole flight-cycle. That is why traditional props are robbing us of at least 40% of efficiency:

Morphing Blade Propellers

The Stallfree propeller technology is based on application of morphing blades that have controlled deformation. They do not rotate but twist – just as the vector field of the airspeed twists, when looked at along the radius of a working propeller. Full alignment of the resulting wind and the blade sections can be achieved practically at any speed. This makes it possible not only to design aircraft never seen before but also to break efficiency records at the same time.

One example: the Stallfree propeller concept makes it possible to build an efficient, propeller driven aircraft with VTOL (eVTOL) capabilities and a 0,8 Mach top speed.

Tilting rotors are driven by high performance but low-mass electric motors allowing the aircraft to have outstanding agility.

( Zoom in 200-300% to watch slideshow. )

Importance of the

TILTROTOR TECHNOLOGY

Today, many professionals regard Tiltrotor Technology (TT) as an additional complexity that makes aircraft design more difficult.

Near future will show the opposite is true. TT will make aircraft design simpler!

TT will be transformed into the most basic steering system of aircraft.

TT shall become the most effective steering system of the history of atmospheric flight!

It is because TT has a direct connection with the main equation of flight. More than that: TT is an expression of the main equation of flight:

 W + L + T + D = 0           (1.)

(The vector sum of weight, lift, thrust and drag is zero.)

TT makes it possible to directly manipulate the above flight equation. By changing the size and angle of the motor- (or propeller-) thrust relative to the aircraft weight the pilot can directly alter values of practically all elements of (1.).

TURBO-FANS & -PROPS