Objectives

Using the previous prototype as a starting point, Omnidea's objective is to improve the airborne module (ABM) for it to be able to operate above 500 m of altitude and withstand wind gusts up to 18 m/s. To operate as an observation platform the ABM must be able to carry payloads. The payloads used are:

UAVision UXG-351 gimbal
MiniSAR antenna by MetaSensing.

The payloads are carried one at a time regarding the mission objective: terrain observation or terrain mapping.

Reduce the number of operators requiered to deploy/secure the ABM during take-off/landing procedures, as a first step to automate the system.

The ABM shall perform a 24 h continuous flight and comply with the laws for high altitude tethered systems for day and night flights. The ABM must be properly signalized in order to be seen by aircraft pilots or other airborne systems.

How does it work?

The Magnus effect, the operating principle of this platform, is a physical phenomena occurring for rotating rounded-cross section bodies (cylinders, spheres), immersed in a fluid in motion. The rotation pushes fluid against the incoming fluid in the bottom part of the body and extracts fluid in the upper part of the body; this creates region of increased pressure in the bottom part and of decreased pressure in the upper part, thus generating aerodynamic lift. This force is, hence, dependent on the speed of the flow around the platform and the rotation of the platform itself, both parameters (free stream flow, U and rotating speed, w) increasing the magnitude of the Magnus effect as they increase.

System overview

The airborne module (ABM) consists in a tethered blimp filled with Helium gas. The envelope has a cylindrical shape and it is made out of three layers:

the inner layer has low helium permeability,
the intermediate layer withstands abrasion
the third layer confers the structural resistance to the envelope.

Attached to each side of the balloon there is a rim, an electric motor, a transmission system and a mechanical arm (boomerang).The cable module is composed by a set of tether cables that connect the balloon to a winch. The main cable connects the main winch to the bridle point. At the bridle point the main cable is split into two cables that are connected to each ABM’s boomerangs.The electronic and communication box is fitted near the bridle point and it allows to control and to receive telemetry data from the ABM.For the take-off and landing operations a set of auxiliary winches are used to properly deploy and land the ABM.There is an auxiliary helium supply system that compensates the leakage of small quantities of helium to the atmosphere during flight.To carry the payload a lightweight tubular aluminium frame is hanged in the dyneema cables near the bridle point.At the ground station the operator can control the ABM’s flight, the winch systems and the payloads.

Project Plan

Assessment of current aeronautical safety and security related regulations in order to identify potential requirements, taking into account the proposed system for the selected locations.
Safety and security assessment considering environmental aspects related to the implementation of the aerial platform system.
Upgrade and develop the necessary components for the ABM, so that it can operate continuously during 24 h at medium altitude, as an observation platform.
Perform a series of flight tests at different altitudes to test the new components including the payload carrying structure.
Operate the system for a 24 h period continuously with a payload.

Key Issues

The fact that aeronautic regulations will demand signalization of the tether an enduring and light weight system must be developed.
The ground station that has to cope with all the data, power and gas transfer while withstanding the traction loads caused by the aerodynamic forces on the platform, without damaging the tethers or its components.
The ABM's envelope pressure variations need to be handled by keeping the same pressure differential between atmosphere and balloon internal pressure in order to maintain constant structural rigidity.
The ABM needs to be rotating to generate lift, otherwise it will fall (for higher altitudes the ABM's buoyancy is lower than the platform total weight).

Expected Main Benefits

The completion of this project allows Omnidea to anticipate its arrival to the aerial platforms market, contributing to an increased recognition of the company among the international community. Furthermore, the project provides privileged access to scientific and technological systems both nationally and internationally, as it is of prime importance for the continuation of research and the development of platform activities.

Regarding the existing competitor systems, Omnidea’s LEMAP can carry substantially higher payloads when compared to other alternatives of a similar size and at higher altitudes. Long endurance operation with a better performance, maintaining its position for a range of wind speeds where others solutions suffer limitations. The ABM operation is quite straightforward; the operator or computer only has to control the winches to provide the correct cable length and the balloons rotational speed.It can be easily modified to accommodate different payloads, up to 20 kg.

The ABM can be disassembled and stored in a container for transportation. The assembling process takes less than a day’s work. It can be fitted on moving platforms such as ships to improve their radar signal or as higher observation platform.