SSG-AERO has teamed up with Conseil & Technique, Altitude R&D and Didier CAILLEAUX (helicopter pilot) to design and develop a new drone concept : the Dravion.

Dravion is a french short for Drone + Avion, meaning a Drone and a plane at the same time.
The main idea behind the dravion is to solve the high speed limitations of the quadcopter.

The dravion combines the architecture of the mutlicopter (fixed propellers) with integrated wings, offering an simple yet very efficient architecture:

• As a quadcopter, the dravion offers VTOL capability and multicopter mobility.
• As a plane, the dravion offers reduced consumption in cruise.

Yet the dravion remains simple as its patented concept requires no mobile propeller to transition from one mode to another, a key asset when it comes to certification!

SSG-AERO has been in charge of the aerodynamics of the first demonstrator.
Starting from a blank page, with only propellers and engines, we designed the shape in two month using Ace of Aircraft 3D steady solver on a unbuntu 64 cores server.

With the support of ACE, the initial meshing parameters were quickly set, and we could then easily work on the optimization of the craft, watching the following pattern :

• General performance: lift, drag and longitudinal moment were key to evaluate the speed of the drone, and proved to be very close to the final results as power consumptions match reasonably well the measured data during the tests
• Local optimization: using the native visualization tools, we were able to assess the local mismatches between the geometry and the flow
• Construction requirements: with Conseil & Technique we took into account the construction tools to simplify the whole craft and integrate the propellers and landing system
• Stability: the craft was designed to be naturally stable in all axis to ease the work of the propellers in flight
  

• Propellers impact: when the design started to converge and the weights got more and more realistic, the propellers came into play and were integrated into the simulations. The propellers were modelled using a classic disc actuator model using Ct and Cp curves and setting the rpms for front and rear propellers. The simulations proved to be of major importance as the performances of the drone were strongly influenced by the propellers. The geometry did not require much changes as it proved to be quite tolerant, but the rotation direction of the propellers proved to have a strong impact on the performance of the craft.
  

Since 2019, SSG-AERO develops modules inside the COSAPP environment for SAFRAN.
https://cosapp.readthedocs.io/en/latest/

This systems offers integrated solvers and can build complex systems using different physical models.
On the Dravion, we used cosapp to solve the operating points using a structure close to this :

By doing so we were able to predict the performance and behaviour of the complete drone with its propeller, and deduce the performance before feeding the simulator run by Altitude R&D.
This tool proved to predict well the drone performance, and perfectly matched the longitudinal results from the simulator, just as the simulator matched the measured results from the tests.
The next dravion iterations will use this tool to evaluate the aero and propellers improvements, or a change in size.

The tests confirmed the predictions!
The Dravion flies fast but burns less energy!

The effect of the propellers has also been validated by the tests!
The team is now working on numerous real world use cases!

More very soon!

Guy VALEMBOIS - CONSEIL & TECHNIQUE / Design & Structure
Romain CHIAPPINELLI - ALTITUDE R&D / Simulation & Control
Didier CAILLEAUX - DC / Pilot
Stéphan AUBIN - SSG AERO / Design & Aerodynamics

Ace Of Aicraft: www.aero-ce.com/ace-of-aircraft/
COSAPP:  https://cosapp.readthedocs.io/en/latest/

Yves Goupil and Georges Gazuit were then studying a new concept they baptized Hydrofret, to move the freight transport bases from the classic airports to the harbours, in order to minimize the number of airplanes flying over inhabited regions, as well as limit the saturation problem we are currently witnessing.
Their seaplane is not restricted to the classic limitations of air-based aircrafts and could provide a global solution to a high number of potential problems that will occur in the next 20 years.
At least, it is worth have a thought about it.

This paper discusses all the simple methods developed in SUPAERO to study the different aerodynamic ground effects and understand their main characteristics. It gives a student point of view of this complex phenomena, and illustrates some possibilities of easy studies of both the Venturi and the ”lifting” ground effects. It is clearly focusing on experimental approaches, and the results must be considered for their tutorial aspect. After a short presentation of the different constraints due to the presence of the ground and the ways used in the case of the paper to solve it, the case of the Mercedes CLK-GTR and its study will be presented, followed by a more classical study of the WIG  phenomenon in wind tunnel.

Hanno Fischer sadly left us in 2024, and leaves an impressive legacy of innovative planes and flying ships. In 2001, he and his team had just certified the FS8 (now Airfish 8) with GL, and were developing the Hoverwing technology which would lead to the development of the Hoverwing 20 and WSH 500. This presentation is very interesting as it shows the complexity of the works to be done to properly design an efficient flying ship such as the Hoverwing.

The second generation of Lippisch ground effect configuration is currently under development at Fischer Flukmechanik. The development of a full size prototype, the 2-seater HW-2VT proved the concept of the Hoverwing technology to be an efficient and economically viable solution for take-off. In this paper are presented the requirements for the Hoverwing 80-seater from the German authorities as well as some of the results and methods that permitted the validation of the concept.

Hanno Fischer sadly left us in 2024, and leaves an impressive legacy of innovative planes and flying ships. In 2001, he and his team had just certified the FS8 (now Airfish 8) with GL, and were developing the Hoverwing technology which would lead to the development of the Hoverwing 20 and WSH 500. He took time to simply show some videos which were at the time a discovery for most of the attendees (this was before youtube) and discuss with the students.

Hanno Fischer presented a 20 minutes movie showing the main part of the development of the ideas of Ing. Alexander Lippisch on reversed delta wings in ground effect from the X-112 to the X-114, and their successors developed by Fischer Flugmechanik and AFD - Airfoil Development GmbH. Most of these movies will soon be available on the WIG Page, in the movies section. To illustrate these movies are presented here two pictures of each craft with a text extracted from the WIG Page, courtesy of Edwin van Opstal.

Kirill V. Rozhdestvensky is a renowned teacher from St Petersburg State Marine University (SMTU), with expertise in ground effect, cavitation, and asymptotic methods. His works extend the approaches of Prandtl to ground effect and provide simple and powerful results. Kirill is an international advocate of ground effect and of SMTU, and was very good at explaining things. During the event, he also kindly helped everyone communicate with his Russian colleagues.

The lecture discusses a simplified mathematical model of an ideal fluid flow past a large aspect ratio wing(s) near a solid underlying surface based on the Ludwig Prandtl’s concept of lifting line. With use of the method of matched asymptotic expansions the results are derived in a straightforward manner without solving traditional integro-differential equation(s) for the case of a single lifting line and of a tandem, comprising two wings moving in the same horizontal plane near the ground. The concept implies that the chord of the wing(s) is much smaller than its span. The distance of the lifting line from the ground and longitudinal separation between the wings in the case of the tandem are assumed of the same order as the span. In the limit when relative ground clearance, based on characteristic span of the wing(s), tends to zero, the flow model can be still further simplified through ”quadruplication” of relevant integro-differential equations are reduced to ordinary differential equations of the second order. The latter limiting description of a lifting line or lines in extreme ground effect yields simple analytical formulae for aerodynamic coefficients.

Graham Taylor is a true ground effect enthusiast. By then he was running a website called the “Ekranoplan Man” where he shared pictures and videos of his scaled models inspired by the Russian and German flying ships and hydrofoils. Youtube would have been his second home, had it existed. He was also very interested in the economical efficiency of the flying ships, and had published some papers adding economical hindsight in what was at the time a very technically oriented environment. This meeting helped create bonds between him and Hanno Fischer, which would lead to the creation of the Hypercraft company. Here Graham kindly agreed to make a paper to help students gain time in designing a radio controlled ground effect model, the first step to really experience the difficulty of this type of technology. Later that day Graham made a demonstration of this model on the Canal du Midi, adding demonstration to theory.

During the last 50 years scientists professors and students have written many learned papers which explore the complexities of ground effect aerodynamic theory. Although these theories may be visualised in the minds eye, the underlying objective of such work is to realise the WIG concept in physical reality. Research facilities around the world have produced some very significant models and dramatic prototypes, but the cost of such work can appear off-putting to those without strong financial backing. This paper demonstrates how accessible the subject of WIG really is and how, with very few facilities and at very little cost, it is possible to build a working model to explore the WIG phenomenon. The first part of this paper discusses the authors’ experiments, while the second explores approaches to making a successful model. As this paper is about the authors’ experiences it is written in the first person. NOTE The discussion was recorded but Graham had had his microphone taken from him, making his answers so low they are not understandable and hence were edited and cut.

Gunther Jörg is the inventor of the tandem airfoil flareboat, a flying ship which was very simple in appearance and very practical, yet required more than a decade of fine optimization to reach its final form, and even involved 2D airfoil optimization using CFD. The simplicity of the design and the true naval approach of the ship (only a throttle and a wheel – no flaps) helped it win numerous prizes, and numerous ships were designed, from 4 seats up to 12 seats. He is here accompanied by his daughter Ingrid Schellhaas, as a translator but also a commercial representant of the tandem airfoil concept, who pursues the impressive works of her father. Again it was a true chance to share some time with the inventor of one of the type of ground effect ships, and also to see some quite rare videos of their flights. Tandem Airfoil Flareboats are based on the wing-in-ground-effect principle. The special construction of the TAF is a twin-wing-system without elevator and aileron. The construction is self-stabilizing by its shape, using the buoyancy between water surface and wings. With a prototype we investigated experimentally the following performance characteristics like displacement, manoeuvring state, transient from skimming and back, flight in ground-effect. Manned crafts of different sizes and materials confirmed the excellent TAF features. The paper will also address important features of safety and economy as well as international acceptance by the International Maritime Organization. NOTE Video quality is below average due to the state of the VHS. We are deeply sorry for this as it does not reflect the quality of the material presented here.

Tandem Airfoil Flareboats are based on the wing-in-ground-effect principle. The special construction of the TAF is a twin-wing-system without elevator and aileron. The construction is self-stabilizing by its shape, using the buoyancy between water surface and wings. With a prototype we investigated experimentally the following performance characteristics like displacement, manoeuvring state, transient from skimming and back, flight in ground-effect. Manned crafts of different sizes and materials confirmed the excellent TAF features. The paper will also address important features of safety and economy as well as international acceptance by the International Maritime Organization. NOTE Video quality is below average due to the state of the VHS. We are deeply sorry for this as it does not reflect the quality of the material presented here.

Aleksander I. Maskalik was a renowned engineer and led the design of numerous civilian ekranoplans and hydrofoils in Russia.
He is a winner of the Lenin prize, and worked under the guidance or Rostislav E. Alekseev, then with Dmitrii N. Sinitsyn.
He wrote numerous books on the matter, and describes here the main problems which were solved at the time by the Soviet team to create the big ekranoplans.
If you still have some Russian ice cream left…

The former USSR is among the leading country in the development of ground effect technology. Under the guidance of Rostislav E. Alekseev, a high number of different prototypes and operating crafts were developed and tested. This experience is presented in this paper that also offers an overview of the main questions to be answered for the wide development of ground effect technology in the future.

Kirill V. Rozhdestvensky is a renowned teacher from St Petersburg State Marine University (SMTU), with expertise in ground effect, cavitation, and asymptotic methods. His works extend the approaches of Prandtl to ground effect and provide simple and powerful results. Kirill is an international advocate of ground effect and of SMTU, and was very good at explaining things. During the event, he also kindly helped everyone communicate with his Russian colleagues. 

This lecture discusses some mathematical models of high speed wing-in-ground effect marine vehicles operating in close proximity of an underlying surface. Mathematics associated with extreme ground effect is shown to be considerably simplified, so that the description of the flow past a lifting surface of infinite aspect ratio can be reduced to 2-D or even 1-D differential equations. The relevant mathematical models yield closed-form solutions useful in design of vehicles of new generations.Cliquez ici pour modifier un élément..