Micro-LTAs for the 21st Century
Commercial applications for Flying Drones have seen unprecedented rise during the last decade and there is no perceived slowdown in the decades to come. Every month, we are witnessing a new and novel mission accomplished by these small, affordable, remotely or even autonomously controlled multicopters. As appealing as they are, they are certainly not without limits, with the most glaring one being their extremely limited flight endurance when carrying any revenue generating equipment. Missions are often limited to a couple dozens of minutes!
ATHENA’s proposal is a novel approach to small scale remotely or autonomously operated aircrafts consisting of a micro lighter-than-air platform that can maintain flight missions for days at times at slow speeds and in surprisingly silent mode.
There are innumerable missions that fit these criteria’s... missions ranging from observation, surveillance, inspection, communication relays, de-mining, specialized transportation & in-flight releasing, filming and outdoor advertisement.
We recognize that an LTA aircraft is by no-means the perfect solution and one of its most notable drawbacks, is its low speed and therefore its limited usage in windy conditions.
However, this is actually turned into our competitive advantage. Even though a wealth of missions can and should be accomplished at low speed over a long duration, we realize there is additional income potential provided by missions performed in winds up to a reasonable 15~20 knots. A traditional Blimp-type airship has very high inherent drag both due to its large projected frontal area as well as its large overall friction-prone wet surface. Such conventional shape together with lenticular ones cannot take advantage of aerodynamic side lift coming from airflow generated by wind.
ATHENA has devised novel architectures that will take advantage of wind-created airflow and generate additional side lift to complement its electric propulsors. An airship of small dimensions can easily be built vertically or into an annular shape in the spirit of a Parasail in order to generate side lift once it is rotated at a proper angle of attack. Such a ship can now operate in higher wind conditions and actually increase its speed without using any electric energy... something a VTOL drone can never achieve!
This aerodynamic effect can nowadays be made possible with modern advanced control algorithms that recent computing capabilities provide.
We believe that A.I. will play a determining role in future developments of this technology. Basically, in the near future, such airships could steer fully autonomously, with little to no human input, in order to optimize its on-board energy management and, equipped with on-board late-generation solar panels, could fly autonomously for weeks at a time with virtually no operational costs to its operator.
ATHENA has a whole different approach to Micro-LTA architecture to allow for full stationery isostatic flight as well as to benefit from wind-produced aerodynamic lift. Taking inspiration from Parasails effortlessly lifting active adventurers down mountain sides and aggressively pulling Kite-surfers along windy beaches, we thought... why couldn’t such a Parasail be inflated with a lighter-than-air lifting gas? They very well could! But, for a remotely controlled Micro-LTA to fulfil low to moderate speed missions, they would have to take a whole different architecture. Hence, we ended up with the vertical “mast” configuration as our first likely candidate. This architecture allows us to reduce the weight of our lifting bag which is the biggest weight contributor on a non-rigid airship. Since the payload is located directly under the full horizontal projection of the bag profile, this one doesn’t see any bending load applied over its envelope which would normally require a thickening of its gauge. Because we are dealing with a rather small ship of reasonable height, the normal pressure gradient experienced inside its gas volume is not an issue for us and we are allowed to slightly raise internal pressure to increase the overall stiffness of this long vertical column. The “trick” here is to limit this long inflated “sail” from excessively bending sideways when side lift is generated from the wind flow. Things are therefore going in the right direction for us!
Having yaw control from our two vertical electric propellers located symmetrically abeam of the ship’s middle plane, we can orient at will this vertical parasail in relation to the wind in order to generate side lift and constantly adjust the ensuing drifting and projected course aided by on-board sensors and advanced flight control.
Our second likely candidate for a wind-induced aerodynamic airship architecture comes from late 20th century experimental airplane research around annular wing designs. This has long been one of ATHENA’s administrators private research subject and never did the thought occurred that such application would reap its benefits from an LTA usage. For an insight on an actual flying annular wing prototype, you are welcome to tune-in the following YouTube video provided here:
On airplanes, annular wings generate lift without induced drag and forego the need of using an empennage altogether. A low speed Micro-LTA would not be affected by induced drag but it would definitely lack provisions for any empennage. Annular wings produce lift all around their periphery and so we would gain from slight vertical lift as well. The main benefits would actually be a more stable and rigid pressurized gas envelope in high winds that would provide equalized side lift at each horizontal quadrant. The height of the gas envelope would be much smaller even though this architecture would be slightly heavier. Instead of a vertical bag measuring between 8 to 12 meters high, the diameter would approximately be divided by a factor of π (or ~3.14).
Our third concept is a twist on the second one where the Torus is rolled instead around the y axis. We cannot call this an Annular wing anymore but it is rather aToroïdal wing where the center opening acts as a Vane. It possesses the same pressurized gas envelope stiffness & stability benefit as our second concept. In addition, such 3D shape brings a much smaller frontal area where tighter passages becomes an issue. And, as a bonus, it is lighter boot!
As in most projects, ATHENA has a full Business plan available on demand.