Overview: EON800 Tether System for Freefly Systems ALTA X

EON800-AX Overview | Freefly Systems ALTA X

Last updated 1 month ago

Overview: EON800 Tether System for Freefly Systems ALTA X

EON800-AX Overview | Freefly Systems ALTA X

XM2's EON800-AX Tether System is a bolt-on, tether power and control solution for the Freefly Systems ALTA X. High-voltage cabling and four fiber optic cores are embedded within the Tether Fiber Cable for powered connectivity. Generator Power is transmitted to the Tether Ground Station (TGS). The TGS then delivers power and fiber connectivity through the Tether Fiber Cable to the ALTA X (via the Air Power Unit) and its payloads. The EON800 has been specifically designed to securely provide the ALTA X with control, connectivity and extended flight time.

EON800 System Components

EON800 Air Power Unit for ALTA X | EON800-AX APU

The EON800 Air Power Unit (APU) is engineered for easy and rapid installation, seamlessly integrating with the ALTA X. The APU's front ports deliver power and fiber connectivity from the tether cable to the ALTA X. To keep the power components running efficiently, the APU fans pull cool air through the system.

Quick-Release Mounting Pins directly attach to the pre-existing attachment points on the ALTA X Battery Tray.

The APU is designed to mount two 6S 10,000 mAh backup batteries, each plugging into the APU panel-mounted connections. Power Output Pigtails are installed on the APU, connecting to the ALTA X standard Battery Inputs.

The serial port connects the APU with the ALTA X flight controller.

EON800 Tether Ground Station

The EON800 Tether Ground Station (TGS) distributes high-voltage power from an energy source, through the tether cable and up into the ALTA X via the APU. The TGS is designed to fit around a 4U enclosure for rack mounting. The system's front panel includes an LCD user interface, allowing operators to monitor the ALTA X tethered performance.

An ethernet port on the front of the TGS provides a UDP MAVLink feed to the ALTA X flight controller.

'ALTA QGroundcontrol' is enabled through the tether cable, similar to conventional usage over USB or Wi-Fi.

To FlyByWire, establish a connection between the TGS, a laptop and a preprogrammed HOTAS for ALTA X.

When flying the ALTA X over the MAVLink network, be very careful with the configuration, as in-proper configuration may result in a crash, or arming the aircraft unintentionally.

For safety purposes, Freefly Systems strongly recommends ensuring that the ALTA X is capable of manual flight mode. This serves as a crucial safety feature in the event of a GPS malfunction, enabling essential manual control of the aircraft.

System Performance

Power Draw and Performance Details

The power draw of the ALTA X depends on the weight the aircraft is carrying, as well as other factors like wind speed and altitude. In ideal conditions at sea level, the graph below shows the current draw of the ALTA X when powered by the EON800 system. The EON800-AX Air Power Unit provides 46-50V DC power to the Drone and Payload. The output voltage of the Air Unit varies with load. The graph below shows how output voltage varies with current draw.

How Much Weight Can The System Carry?

The maximum capacity payload for the EON800 powering the ALTA X depends on many factors. The graph below shows the maximum possible payload for any given altitude, at various payload power draw levels. These figures are calculated for a drone using 6s 10,000mAh batteries, using XM2 SLG-20 Retractable Landing Gear. These maximum payload weights reflect the limitation on gross weight discussed below.

Function of the Backup Batteries

The backup batteries operate in parallel with the power system. The voltage of the backup batteries will float at the output voltage of the tether system, depending on the load. This means that as load increases (takeoff), the backup batteries will discharge, and as load decreases (landing), the backup batteries will be charged. The voltage of the backup batteries will also fluctuate as the batteries handle burst current to react to wind gusts, etc.

The backup batteries are designed to supply burst current and reserve capacity, acting as a backup in case of a power system failure, like when the generator runs out of fuel. This backup ensures the capability for emergency landings. The appropriate size of this backup battery depends on the aircraft and payload. For example, a suitable size for the 25-30kg ALTA X would be two 6s 10Ah batteries in series.

The EON800 may cause a reduction in voltage output under heavy loads, impacting the backup batteries' ability to maintain full capacity. When choosing the right battery size, consider this aspect for optimal performance.

Fiber Communications

The Tether Fiber Cable consists of four single-mode fibers. One of these fibers is specifically allocated for controlling the ALTA X, while the remaining three fibers are available for the users payloads.

Typically, two out of the three payload fibers establish a full-duplex connection with the payload device, while the third fiber serves as a backup or secondary link. This third fiber ensures continued functionality in case of any damage to the primary fibers and can also support simplex or half-duplex modes for an extra device. We've designed this versatility to enables multiple payload setups, such as operating an LTE radio and a camera simultaneously, each with its independent fiber connection.

The EON800-AX Air Power Unit has a serial port to connect to the ALTA X flight controller. The Ethernet Port on the Tether Ground Station provides access to this MAVLink feed via UDP.

Notes on Power limit, Payload, and Gross weight

Understanding the difference between Gross Weight and Maximum Takeoff Weight (MTOW) is vital when operating the ALTA X tethered. The Gross Weight includes the weight of the flying tether cable. To ensure optimal performance and safety, it's recommended to operate the ALTA X in a tethered configuration with a Gross Weight not exceeding the specified MTOW of 34.8 kg (76.8 lbs) set by Freefly Systems.

For flights aiming for higher altitudes while adhering to the 34.8 kg (76.8 lbs) gross weight limit, it is essential to consider adjusting the takeoff weight, potentially as low as 30.4 kg (67lbs). This adjustment compensates for the increasing weight of the tether cable during ascent. These limitations are directly reflected in the performance graphs provided in this guide.

The EON800 has a maximum delivery capacity of 100 Amps to the aircraft. To optimize performance and avoid strain, it is advisable to maintain the current draw below 90 Amps. If the operation exceeds 95 Amps, a warning message on the LCD will be triggered to alert the user.

The continuous power draw of the aircraft is influenced by various factors, such as takeoff weight, tether weight, wind drag, altitude above sea level, and payload power draw. This demonstrates that while you might be able to carry a specific weight in calm, low-altitude conditions, it might not be feasible to carry the same weight at higher altitudes with strong winds.

When the aircraft exceeds the power systems capacity, it safeguards itself by limiting the power. This extra power then comes from the backup batteries, causing them to slowly lose power. The system alerts you, allowing you to either fly lower to use less power or land the drone and lighten the payload. If the aircraft draws more power than the power system can provide, the current will be limited to protect the power system from damage. Excess power will be drawn from the backup batteries, which will cause them to slowly discharge. The system will alert the operator, and the operator can reduce altitude to reduce the power consumption, or land the drone and lighten the payload.

Heavy-lift Drone Integration

This guide has highlighted how the EON800 tether system works specifically with the Freefly Systems ALTA X. It's worth noting that the EON800 tether system can potentially integrate with other UAVs using a 12-cell lithium battery setup, as long as their power draw aligns with the limits of the EON800 System.

If you're considering integrating the EON800 with different aircraft, please reach out to us for more information. Our team is ready to discuss your unique application and requirements.

Technical Integration Contact: BD@XM2.com

Tether System Specifications

Tether Ground Station (TGS)

Air Power Unit (APU)

Tether Fiber Cable

Last updated 1 month ago