The Ultra-compact VTOL aircraft- UVA is a design concept which explores a new lift system for Vertical Take-off and Landing (VTOL) Aircraft. It is based upon two thrust units with Ventury effect potentially creating a vehicle with no external moving parts, reduced vehicle aerodynamic losses compared to previous VTOL technologies and substantially creating an induced lift even in static or quasi-static conditions.

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Ultra-compact VTOL aircraft- UVA for civil and military applications
Introduction
The compact VTOL aircraft are irreplaceable means of transport especially for operations where
space is limited – such as surface vessels, mountains and urban environment. Further
technological advances in areas such as Distributed Electric Propulsion-DEP, improved
aerodynamic configuration or composite manufacturing processes will lead to smaller, more
capable VTOLs ensuring their continued relevance in the aircraft sector.
The low-cost VTOL craft is particularly attractive for recovery/transport applications. They have
small footprints and lower signatures. They also save costs when compared to helicopters and
are easily operable in a variety of areas.

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The Ultra-compact VTOL aircraft- UVA is a design concept which explores a new lift system for
Vertical Take-off and Landing (VTOL) Aircraft. It is based upon two thrust units with Ventury
effect potentially creating a vehicle with no external moving parts, reduced vehicle
aerodynamic losses compared to previous VTOL technologies and substantially creating an
induced lift even in static or quasi-static conditions.
State of the art
The rotary-wing aircraft, or helicopter, is a common type of VTOL aircraft. Helicopters have
large rotors that provide both vertical and horizontal trust. For the rotors to perform this dual
function across of range of airspeeds, the rotors are typically quite complex. The rotors
generally rotate at low speed. This results in heavy transmissions between rotor and engine.
Because of the mechanical complexity across the entire vehicle system, many parts are single
points of failure. Because of this lack in redundancy, frequent inspections and maintenance are
required to keep the vehicle safe. Moreover, helicopters are large and unprotected from hitting
nearby obstacles and any contact of the rotors with external objects can be catastrophic.
Combining the vertical take-off capabilities of helicopters and the cruising abilities of fixed-wing
aircraft, the Lilium Jet aims to be significantly quieter than other VTOL vehicles such as
helicopters, thanks to its 320 kW (435 hp) rechargeable-battery-powered ducted fan thrusters.
Based by independent estimations made by several experts and prestigious publications, this
simply ducted fan propulsion, proposed by Lilium, based on a pure electric VTOL architecture,

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seems to be insufficient for a reasonable range, even the aircraft flew a three minutes’ flight of
a prototype without useful load.
Consequently, to increase the range of ducted fan propulsion is more suitable to use a hybrid-
electric architecture. Other aerodynamic improvements are also recommended.
Ultra-compact VTOL Aircraft- UVA
The new concept UVA is a practical multi-passenger aircraft powered by a hybrid-electric
energy source and at least 18 ducted fans, arranged in two thrust units, which each produces a
straight flow of air. The ducted fans provide both vertical and horizontal thrust and rotation
speed management of the ducted fans control the aircraft’s direction/rotation movements. The
ducted fans use a thrust augmenter system with Venturi effect which increases the traction
force and reduce the noise. This is primarily because it allows the creation of an extremely
compact aerial vehicle which has VTOL capabilities and high lifting efficiencies. The thrust
augmenter propulsion with thrust units containing a plurality of electric ducted fans was first
described in the company’s patent RO132306 registered on 15-06-2016.
UVA can take off and land vertically (VTOL) and because of its small dimensions, it can operate
in confined spaces such as close to or between buildings, near trees or in confined areas that
other VTOL aircraft such as helicopters cannot access.

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Even in is the simplest variant, without wings, UVA has a configuration that is safe, quiet and
efficient as well as easy to control, high compact and which can accomplish vertical takeoff and
land with the transition to and from forwarding flight.
In operation, the fuselage of the aircraft is inclined towards the front.
Take-off Forward flight
UVA technology employs a novel suite of aerodynamic innovations that make it possible to
design a vehicle that is the size of a car and can carry the same number of passengers but can
fly with no exposed rotor.

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In a second variant, on each thrust unit, various wing configurations can be mounted, which will
support the vehicle in forwarding flight.
In a third variant, the side thrust units can be rotatably mounted on the fuselage and each of
them contains a folding wing.
In operation, the wings are extended in forward flight and the airflow is directed backwards.

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A winged version of the UVA has the following parameters:
No. Characteristic
1 Number of ducted fans 18
2 Duct diameter 0.2 m
3 Max. take-off weight 1400 kg
4 Payload 420 kg
5 Cruising speed 200 km/h
6 Estimated maximum speed 250 km/h
7 Range 500 km
8 Maximum power (ICE + battery) 600 kW
9 Estimated noise level 78 dBA

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UVA is a scalable concept. As an example, a single person ultra-compact aircraft can be
achieved with the same technology and hybrid-electric power source.
Propulsion system with thrust augmenter
The multi-passenger aircraft uses at least 18 electric motors making the system highly
redundant. If one or two of the electric motors failed, the aircraft continues to operate safely.
To improve the disk loading value with around 50% UVA can use a new type of ducted fans with
thrust augmenters, respectively having two parallel air streams.

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The propulsion system with thrust augmenters offers the following advantages:
-The thrust augmenter increases the volume of air propelled with a corresponding decrease in
average air velocity
-The bypassed air is moving at a much faster rate of speed than the ambient air but with a
lower rate of speed than the inner flow; this reduces the speed difference between the inner
airflow and the air surrounding it, further improving efficiency and reducing noise
-The jet contact surface with the ground is very much increased reported to a simple ducted
fan, reducing the required power and the erosion of the ground surface
-The recirculation airflow is diminished in take-off
-Adding a second duct is increased the behaviour of the propulsion system as an airfoil
-The value of disk loading is very much reduced (and improved).
Hybrid-electric energy source
The core of the hybrid –electric powertrain is an innovative internal combustion engine with
the high power density and internal heat recovery for improved efficiency. The engine concept
named RECOVER can operate with hydrogen or with carbon-neutral fuels. The hybrid system is
also redundant because the IC engine activates two generators.

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The RECOVER engine can match the fuel cell efficiency of 40—50% without using expensive,
precious metals in its manufacturing process.
The advantages of the RECOVER range extender:
 High power density between 300 to 500 kW/l;
 Multi-fuel capability by using carbon-neutral fuels including hydrogen
 Reduced CO2 level when uses conventional fossil fuels;
 Dual-use, i.e., military or commercial;
 Compensation of all rotating inertial forces;
 Compensation of all 1st
order oscillating forces (torque compensation);
 Very low vibration caused by torque impulses on the engine assembly and the driven
systems;
 Very low friction losses from the piston - connecting rod-cylinder assembly, the side
force acting on the piston being cancelled by the two connecting rods;
 Low fuel consumption due to the exhaust gas recovery system;
 Significant reduction in production cost;
 Scalable from 50 kW to 2 MW power level;
 Reduced noise level due to the low pressure of exhaust gases in the final stage.
UVA recommended utilization as a commercial vehicle
The provision of a flexible cabin environment will be a more major focus in engineering than
ever been before. As an operator, it would be great to think that you had a base vehicle
platform which carried the end-user to its destination, but the next day it was converted to a
transport platform and was delivering goods to your door. Flexibility is therefore in our minds
when we look at the overall aircraft integration and architecture. From a practical perspective,
being able to customize the number of seats, the amount of trunk space and the level of
accessibility will allow the operator a greater choice in the types of journeys that they can cater
for.

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The UVA architecture as aerial taxi permits the achievement of a spacious cabin for 4
passengers but which also lets enough space for the hybrid-electric energy source.
UVA has 1/4 the footprint of a helicopter with a more spacious cabin. They eliminate the risks
associated with external rotors without compromising any of a helicopter’s payload, range or
hover capabilities. A requirement for an urban-friendly aerial vehicle is to have a reduced noise
level. Ducted fans included in the side thrust units are inherently quieter than an open rotor,
which means that UVA starts at a natural advantage when it comes to noise.
A second application for both civilian and military missions is as air first responder. When every
minute counts, the medical personnel want to have landed at a distance to where help is
needed and continue to the site on foot. Consequently, unrestricted access in emergencies
requires an aircraft that matches the capabilities of a helicopter but flies into places that no
helicopter can access. In this configuration, UVA can transport a stretcher and associated
medical equipment.

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Another application for both civilian and military missions is an aerial truck when a platform is
used to transport equipment.

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UVA recommended utilization as a military vehicle
In a military application, UVA can use a multimodal transport system in which the VTOL vehicles
are easy and quickly deployed in the area of operation using different aerial, naval or terrestrial
means.
Being so compact UVA can be transported on roads from one place to others when need.
Using aerial means as C-17 or CH-47.

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Or being launched by naval means including submarines.
Summarizing UVA can be used as:
-Door to door transport
-Aerial inspection and search
-First responder transport in emergency events
-Inaccessible region assistance
-Border security
-Firefighting including in urban areas
-Troops deployment in limited spaces
-Soldier extraction
-Recreational trips
UVA advantages:
-The control of the vehicle is made in the simplest manner
-Ducted rotors enclosed in the side propulsion units are inherently quieter than an open rotor
-Spacious cabin and minimal footprint resulting in more passengers per trip
-Same propulsion system is used with high efficiency for both vertical and forward flight
-In forward flight, the lift is produced by the wings
-Is a multi-mission vehicle with compact size even in winged versions
-The rotors are protected against contacts

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-It is a scalable concept
-Can transport packages having different sizes
-Has a modular architecture and different configurations for different missions
-An amphibious version is also available
Contact: liviu.giurca@micortec.com michael.soimar@micortec.com