VSKYLABS Contraventus Project

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The VSKYLABS 'Contraventus' research prototype.

Please note that this project manual/instructions is available in an On-Line version only. Simply scroll down in this page to get to the manual section.

Separate native products for X-PLANE 12 and X-PLANE 11, for your selection.

MINIMUM HARDWARE REQUIREMENTS FOR X-PLANE 12

Disk Space: 25GB
CPU: Intel Core i3, i5, i7, or i9 CPU with 4 or more cores, or AMD Ryzen 3, 5, 7 or 9.
(Those with other CPUs should try the demo before purchasing.)
Memory: 8 GB RAM
Video Card: a Vulkan 1.3-capable video card from NVIDIA or AMD with at least 2 GB VRAM
Note: Intel GPUs are not supported by X-Plane 12.

Renewable Energy Glider - Educational Concept Demonstrator

The VSKYLABS Contraventus Project

Explore the fascinating and challenging world of precision flight in an electric powered, experimental aircraft. It is a robust, highly equipped, electric powered prototype design which is initially based on the the MIT 'Daedalus 88' (the human powered, record braking aircraft) design.

Project Introduction

The design concept of the VSKYLABS 'Contraventus' prototype is to experiment and research the practical use of electric power coupled with wind energy utilization for 24 hours battery cells charging capabilities. The 'Contraventus' is a concept demonstrator and educational tool for experiencing some of the fascinating aspects of aerodynamics and flight envelope limitations.

The idea of the 'Contraventus' operation is to drain (consume) the operating battery during an initial climb out to ~5,500 feet QNH, and then recharge it completely while performing an ultra shallow glide, utilizing airflow (forward motion of the aircraft and wind milling). In a series of climb outs and charging-descends, the 'Contraventus' can be flown and recharge during day and night time. Its superb design as an efficient sailplane makes these climb-outs to work like climbing steps for reaching its cruise altitude (the 'Contraventus' is not a pressurized aircraft therefore it is limited by the physiological aspects of a human pilot).

The 'Contraventus' cruise altitude is derived from its electric motor and propeller's maximum RPM. As the aircraft climbs to high altitudes, the actual 100% RPM could be achieved easily in a lower power setting (because the atmosphere is getting thinner), meaning that in a certain altitude, operating the motor at 100% will not generate sufficient thrust within its operation limitations, and the operational ceiling altitude will be reached.

The 'Contraventus' features automatic solar cells, mainly for research purposes . It is a non-operational system at the moment, as the project is focusing on utilizing the aircraft potential/wind energy for recharge. The Solar cells will get into action in future updates of the project, in which the purpose of initial and in-between flights Sun 'refueling' will be its main purpose.

This aircraft design was focused on simplicity in operation, so you can get it flying quite easily and start exploring the fascinating equations of potential, wind and power management, as well as flight planning and any other considerations of your own.

This aircraft will squeeze out the aviator skills of endurance flying, precision gliding, aircraft potential management, electric power management and weather flying.

Autoupdater based on the SkunkCrafts autoupdater (XP12 only) - all updates are being pushed smoothly without the need to re-download the entire base package (base package will be updated every once in a while to minimize the gap).

Pilot's Operating Handbook

Aircraft Power/Electrical System

Motor/Battery:

A Single 10hp electric brushless motor that is being operated by drawing current from a 300AH Battery. By definition, the 'Contraventus' concept is challenged by using a low battery capacity specifications.

Motor/Propeller:

The electric motor is powering a three blade high-pitch propeller in a direct-drive mechanism. The electric motor differs from a conventional, reciprocating engine in several aspects. One interesting aspect is the fact that the electric motor is not an "air-breathing" engine, and does not need oxygen for its operation. In theory, it can be operated at any given altitude...even in space. However, cooling the motor in high altitudes may become a challenge (mainly because the low air-density/low-flowing air cannot transfer heat from the motor effectively). In the lack of proper heat-transfer aids, it could become an operational limit.
While climbing with the 'Contraventus', you will notice that for a given throttle settings, the propeller's RPM will become higher as the altitude will get higher. You will notice that in sea-level, in full throttle, you may get only ~90% RPM, and in approximately 13,000 feet QNH, a full-throttle setting will get to 100% (600 RPM), therefore you have reached the altitude operational limitation for the motor.

Motor/Generator:

The electric motor is connected to a generator. The whole system acts as a 3 blade wind-powered turbine which is charging the battery. The charging times and efficiency are designed only to be plausible, in terms of electrical engineering, and the system is simplified in order to make the a)flying experience b)potential management c)straight forward understanding of the concept.
The generator system will charge the battery as long as the propeller is windmilling. However, windmilling RPM should be managed throughout the charging-descends periods to allow an efficient "on the peak" charging. Descend rate is also an important factor and it should be managed to allow a good RPM vs sink rate ratio.
NEW (from v2.5) - the Contraventus Solar Panels are connected to the electrical batteries and will assist with the charging during day-time.

Landing Gears:

The 'Contraventus' has four fixed wheels mounted underneath the fuselage, with no steering. The aircraft is designed to be launched in calm weather. Take off is actually a "launch"; into the wind, full power, and the aircraft is airborne almost instantly. In real life, launching would be made with ground personnel assistance at the wing-tips.
The landing gears are equipped with a linear, symmetric braking system which is allowing a full stop of the aircraft on sloped runways, and it is to be used also as parking brakes.
You will notice that the 'Contraventus' is quite stiff on the ground run - there are no complex suspension systems for the landing gears. It should not be taxied on unpaved terrain - only paved runways.

Aircraft Controls:

The cockpit features only one control-yoke, for controlling pitch and yaw. There are an electrically operated descent split-spoilers which are activated by a toggle switch in the cockpit (A-BRK). The spoilers are for use when descending for landing (rather than commencing a shallow charging-descent), and it allows the aircraft to develop higher sink-rate while maintaining within its Vne limitations. Also use it for rapid-descent in case of emergency.

The aircraft consists these control surfaces:

All moving horizontal stabilizer (elevator).
All moving vertical stabilizer (rudder).
Split-spoilers (air-brakes).

Use either Rudder or Aileron axis in your joystick to control the Rudder:

In X-Plane, for flight-simulation-pilot-convenience, the rudder is coupled with ailerons (roll) control so you can move the rudder by using your pedals or other method of rudder control in your joystick (twist or whatever) or, you can move the stick as if you are operating your ailerons to induce roll. The flight model will have your inputs (roll or yaw control from your joystick/pedals), and will use it to move the rudder of the aircraft. So, basically it is 100% rudder controlled aircraft, with dual input from your joystick. No setup is required in X-Plane joystick menu.

Cockpit Layout

The cockpit of the 'Contraventus' is straight forward and useful. It has an artificial horizon (on the smartphone screen) and a GPS with a moving map system.

Special Notes:

Switch on/off the GPS is done by pressing (clicking) on its upper left volume knob.
Switching off the Avionics switch will switch off the Autopilot as well.

Aircraft / Mission Operations

In General:
As part of its design concept, the 'Contraventus' is designed with minimum specs in all aspects (with the minimum possible configuration in mind). There are no "extras" and every phase of the flight should be performed with precision, in order to succeed.

Winds and Weather:
One of the base-line considerations when flying the 'Contraventus' is wind strength and direction. This research aircraft is very limited in ground operations on windy conditions, and is a slow-flyer (~30 knots at powered-climb or charging-descent phases) Meaning that you will have to plan your flight route with a close look at the weather, in order to have a successful landing in a pre-defined landing spot. Special care would be taken when flying the aircraft to remote areas such as deserts or over seas. You might find yourself unable to get to your planned landing spot because of bad wind considerations.

Topographic considerations:
The Contraventus is not a rapid climber, and flying over or into the mountains may bring up some crucial VFR real-time route planning, so climbing will be executed safely over the ridges. This aspect, along with the winds and weather considerations may become a real challenge when trying to cross high mountains passes.

Preferred weather conditions should be:

Launch: Calm winds (recommended below 5 knots).
Flight: Calm to moderate wind layers in the operational flight altitudes.
Flying through clouds is prohibited.
Flying through rain and icing conditions is not recommended in the 'Contraventus' because of its electric motor type and configuration. Future models of the 'Contraventus' will have all-weather capabilities (with some limitations).

Ground Operations:
The 'Contraventus' is a "super-glider". Because of its enormous wingspan and its light weight, there are limitations regarding the ground operations and launch conditions; at ground level winds of over 5 knots is would be very tricky to hold it stable, and head-wind launches are recommended. In real life, these kind of research airplanes are brought to the takeoff position with external assistance such as ground personnel who are holding its wingtips upon launch. The 'Contraventus' is a research powered glider and it is not designed to be self-taxied from the hangar to takeoff position. Luckily, a very short (but wide clean) launching area is needed to set it up safely into the air.

Getting Airborne:
keep in mind that you will have to launch the 'Contraventus' in calm weather. Launch is straight forward:

Release the parking brakes.
Apply full power.
Maintain desired heading with yoke control.
Safe flying speed is above 25 knots. Gently pull the stick and once airborne and above 25 knots, manage nose-attitude to obtain the best-climbing-speed. Remember that it will want to turn into the wind, so plan ahead and "keep flying the airplane". Once the airplane is stable in a ~500 feet/min climb, you are good, having a successful launch.
If you insist, you can launch it in windy conditions: apply full power and let it to be "sucked-up" into the skies...you will need nerves of steel though...

Pitch-Trim management (not needed!):
No need for any trim setup (pitch trim), as the aircraft is designed with pitch-trim self-alignment system which will reduce the yoke-pressure gradually and automatically in every stable flying condition. Simply fix the Yoke and the nose into the desired attitude and maintain it steady for about 5 seconds. The elevator-automatic-self-pitch-trim-system will sense the loads and automatically trim the aircraft into that flying condition. Note that in cases of airspeed changes, it will be difficult to follow the changes, therefore, fly the aircraft in a relaxed and controlled rates, so the system will be able to keep up with automatic trim.

Powered-Climb:
Powered climb should be executed in 100% throttle settings 25-29 knots IAS, depending on flying altitude. Note that as you go higher, propeller's RPM will tend to go faster also, in a given power setting, because of the thinner air. You will have to monitor your RPM gauge and use the power within the 100% limitation.

The 'Contraventus' concept of operation is to perform four climb-out and descent phases before reaching the cruising altitude, which is 8,000-6,000 feet QNH. Best rate of climb is achieved while flying in wing-level attitude (not in a turn), so try to maintain your flight path in straight lines. Best (initial) rate of climb is achieved when flying at 25-29 knots (IAS). Rate of climb should be ~500 feet per minute in these conditions.

The VSKYLABS Contraventus unique design may allow several climbing configurations. For example, accelerating to ~40 knots with a lower AOA attitude may induce as much as lift as flying in ~27 knots with a higher angle of attack attitude. However, differences in motor's RPM will vary the battery drainage (even if both of the methods are using 100% throttle). You can try and experiment these climbing profiles.

Pay close attention to electrical consumers:
The VSKYLABS Contraventus is designed with no excessive spares...GPS system, autopilot, landing and navigation lights are all electrical consumers which are needed to be used with minimal operation during the initial climb profile to the 8,000 FEET QNH goal.

Recommended Climbing Profiles

The recommended climbing profiles should be carried out with these airspeeds:

Climbing from 0 - 2,000 feet QNH: 25-27 Knots IAS
The IAS indicator is marked with a green "A" zone for this configuration.
Climbing from 2,000 feet and above: 27-29 Knots IAS
The IAS indicator is marked with a green "B" zone for this configuration.

Recommended Power and Speed settings

Monitoring Airspeed and Heading

In the Airspeed gauge you will notice an arc with four sections:

White: 15-30 knots - Minimum operation speed.
Green: 30-45 knots - Safe operation speed.
Orange: 45-55 knots - Maximum operation speed.
Red: 55-60 knots - Vne zone.
Because of the large wingspan and its low airspeed, even a slight bank will cause the aircraft to turn, so keep an eye on the desired heading.

Power Management:

During the climb, the 'Contraventus' will drain the batteries out. Use the 'Battery Level' and 'Battery Charge' gauges to monitor your electrical power consumption and charging efficiency. The 'Contraventus' is also equipped with active solar panels...but these are not connected to the electrical system in the current version of the project. The solar panels are an experimental feature in the 'Contraventus' prototype no.2.0, however it will have a greater role in future development.

Switches and Instruments

Battery Level:
The 'Battery Level' gauge is set to deliver "Empty/Full" status, for easy readings (you will not have to handle Voltage nor Amps). The needle in this gauge will slowly move from Full to Empty as you are drawing power from the battery for the climbing phase, and will slowly show increase in capacity when recharging.

Charging Efficiency:
The charging efficiency gauge is set up with a green and red areas. During charging descends, when setting up the aircraft is the correct descent attitude and speed, the needle should get to the green area, indicating that best charging rate/sink rate is obtained. Remember that it is an overall charging envelope efficiency indicator.

Generator Charge Switch:
Current version this switch is non-operative. Charging is fully automatic.

Bat Switch, R1 and R2 switches:
These are practically the "on/off" switches for the electrical system. Set the R1 and R2 switches to "on" in order to feed the electric motor power bus for powered flight.

Solar Panels (from version v2.5):
The Solar panel on top of the wings are connected to the batteries and will assist in the recharge process during daytime.

GPS (X-Plane 530 / Garmin 530):
One of the most important avionics in the 'Contraventus' is the GPS system. If you are seriously into flight planning and flight management, you will find all what you need in the X-Plane 530 GPS. Mastering the GPS is a challenging but a very rewarding task, and there are a few manuals around that can be found and used.

Powered Climb Practical Aspects

Use minimal electrical consumers during all flight phases.
Keep in mind to plan your climbing route in straight lines and execute needed turns only, to obtain maximum rate of climb.
The Solar panels on to of the wings are connected to the charging system - they will assist in the charging process during daytime.
In a powered climb-out, the aircraft will climb at full power, while the batteries will drain.
Climb performance is ~500 feet per minute at full power and in the Climb A/Climb B zones. Note that at sea level you will not get 100% RPM when using full-power. Its fine and it's as it should be; RPM will get higher as climbing altitude will get higher.

Charging-Descent Practical Aspects:

Keep in mind to plan your descent route in straight lines and execute needed turns only, to obtain a minimum descent rate.
Once reaching the top-of-climb point (in each cycle), the 'Contraventus' should start the Charging-Descent phase.
Charging-descent is done simply by setting the throttle to Idle (which is practically "off"), and letting the aircraft to saddle down in a stabilized, shallow glide. This is the flight condition in which the 'Contraventus' was designed for; sustained, shallow glide.
Descent rate will be ~150 to 300 feet per minute at indicated airspeed of 29-33 knots (use the orange Charge zone marking in the IAS indicator as a guide).
As the aircraft will glide, you will notice that the 'Battery Level' gauge will slowly show the increase of capacity.
In an unpowered glide, propeller windmilling RPM will vary in respect to the gliding altitude, but should remain roughly around 40%. Please use the recharging efficiency indicator and make sure that the needle is reaching the green marking.
During the powered-climbs and charging descents it is important to turn off unneeded electrical consumers. If turned on - the charging descent will not be optimal. Once at cruise altitude (8,000 - 6,000 feet QNH), electrical consumers can be turned on, if needed.

You can try out and experiment your own cycles, but here is a suggested flight profile to reach cruising altitude:

Aircraft launch (profile for launching from sea-level)
Initial powered climb-out at Maximum Power (90% RPM), 25-27 knots IAS to 3,000 feet QNH (25% remaining on the Battery Level indicator).
Initial charging-descent at idle (windmilling RPM >40%) / 16-20 knots IAS to altitude of 1,500 feet QNH, or to 100% Battery Level.
Second powered climb-out at Maximum Power (100%+RPM) / 27-29 knots IAS to 5,000 feet QNH (less than 25% remaining on the Battery Level indicator).
Second charging-descent at idle (windmilling RPM >40%), 16-20 knots IAS to altitude of 3,000 feet QNH, or to >90% Battery Level.
Third powered climb-out at Maximum Power (100%+RPM) / 27-29 knots IAS to 6,500 feet QNH (less than 25% remaining on the Battery Level indicator).
Third charging-descent at idle (windmilling RPM >40%), 16-20 knots IAS to altitude of 4,500 feet QNH, or to >90% Battery Level.
Fourth powered climb-out at Maximum Power (100%+RPM) / 27-29 knots IAS to 8,000 feet QNH (less than 25% remaining on the Battery Level indicator).
Fourth charging-descent at idle (windmilling RPM >40%), 16-20 knots IAS to altitude of 6,000 feet QNH, or to >90% Battery Level.
You have reached cruise altitude. Commence Climbing/Charging-descent cycles between 8,000 and 6,000 feet QNH. Battery Level in the first cruise-cycle will be around 50% - 90%, and slowly should be stabled and managed between 75% - 100% during the rest of the cycles.
At cruise altitude, RPM can be set to 50% to obtain Long-Range cruise.

Rapid-Descent Practical Aspects

Descending from 8,000 feet QNH might take quite a while, and when required due to an emergency...might not be practical. The Split-Spoilers were designed to allow a rapid descent, safe performance within the aircraft airspeed limitations.
If needed, a Rapid-Descent can be achieved by simple arming the Split-Spoilers of the 'Contraventus'. The spoilers will increase the trimmed rate of descent (29-33 knots IAS) to 500-600 feet per minute, and will allow you to get a safe, 45 knots IAS rapid descent with sink rate of approximately 1200 feet per minute.
At 55 knots, close to the Vne, you will be able to descend at ~2300 feet per minute.
To stop the rapid descent, simply set the nose attitude into a higher position, and once the airpeed is starting to bleed, set the spoilers switch to off.

Update Log

VSKYLABS 'Contraventus' research prototype.
JetManHuss - VSKYLABS (c) 2024 All Rights Reserved

XP12 - v3.3 (3rd April 2024):

Updated airfoils.
Fix to battery slow-recharging bug.
Minor adjustments for PBR renderings in the cockpit.
Fix to transparent elevator animation bug.

XP12 - v3.2 (4th December 2022):

Interior lighting system reset and retuned to comply with the modified X-Plane 12.00r1+ lighting engine.

XP12 - v3.1 (23th November 2022):

Updater software replaced - from STMA to SkunkCrafts.

XP12 - v3.0 (September 2022):

X-Plane 12 initial version released.

XP11 - v2.5 (4th December 2019):

Flight Dynamics Model:
- Descent speed has changed to one which holds the highest lift over drag ratio...this is around ~17 knots give or take, the recharge efficiency indicator will get on the 'green' and should be used along with sink rate monitoring (should fluctuate between -350 to -150 feet per minute...in average).
- It is possible to do the climb outs with full power at ~17-20 knots...however, the recommended shallow climb may be managed with reduced power, and almost the same rate of climb.
- Solar panels are now working side by side with windmill recharge - Solar panels are not effective at night, so flying *into* the night is the most probable approach in prolonged endurance flight.
- Online manual was updated accordingly.

XP11 - v2.1 (9th November 2019):

Flight Dynamics Model:
- Compatibility update for X-Plane 11.40 (including Experimental flight model environment).

XP10 - v1.0 (2015): Project initiated and released.