FTS - Flight Termination System

Hardware Other Hardware
1

Hello,

this topic mainly concerns drone operators in Europe, where an independent Flight Termination System (FTS) is required. Once activated, the system causes the drone to fall and crash within a controlled area where no uninvolved persons are present.

Can anyone recommend a proven FTS that I could install on my drone with an Orange Cube+?

If no such system is available on the market, how could one build it?

How have you dealt with the FTS requirement yourselves?

2

I recall there were a few FTS systems on the market, some could be made independent.

IMHO with reliability of modern electronics and motors independent FTS are a liability, more likely to shot somebody in the face with a ballistic parachute than save life or property. I much prefer the flight controller to be responsible for handling flight termination, including triggering the ballistic parachute.

Ardupilot has output for a FTS heartbeat.

IMHO the key requirements for the system are

  1. It communicates with the flight controller to facilitate
  • Automatic arming on takeoff and disarming on landing (below minimum effective altitude)
  • Manual triggering by the flight controller or by the operator using appropriate MAVLink command
  • Commanding flight controller to run its terminate
  1. It should be able to cut power to the motors only, avionics, landing gear and communications should remain powered
  2. Backup power supply required for triggering must be recharged from the primary battery

Generally there will be 3 components

  1. Ballistic parachute (using pyrotechnic gas generator, have fun with ADR)
  2. Controller.
  3. Power source.
3

I wouldn’t be comfortable with anything in the power train that can cut the power to the motors… It is just another point of failure.
Cutting the motor control signals (pwm/dshoot/can) is more convenient, and you can use small, normally closed SSRs. ESC will stop the motor on signal loss.

  • While i share your point of view, unfortunately in some countries an independent FTS is a requirement, so you must implement it.
  • Spearated power source
  • Separated radio comm
  • Independent from flight controller.
4

Unfortunately not all ESCs stop immediately on signal loss and motors spinning propellers after termination are a sure way of turning the system into a tangled mess.

5

This approach would never pass any certification with which I’m familiar. Everybody wants a separate system that functions without reliance on the flight computer/autopilot.

Unfortunately, I work with systems where the FTS is tightly integrated/coupled to the design of the system overall, and they are not available as COTS products, nor do I operate in the EU, so I’m afraid I’m not much more help here.

6

Yeah, i encountered some, there we added the necessary delay to prevent props get caught the chute lines. CAN ESC’s are stopping almost immediately.

1 Like
7

True, I wonder if the legislators did any math on that requirement assuming MR with redundancy like octoauad.

IMHO tight integration is the only way to have effective FTS that won’t shot the operator.

On other note are there any exemptions (in EU) in hazardous material transport rules for pyrotechnics required for ballistic parachutes?

8

No one cares how redundant your computer or physical prop layout is. The assumption is that the computer will fail and cause a fly-away or powered excursion. After some non-trivial amount of data collection (mean time between failures, etc), it MIGHT be possible to reduce the requirement for an FTS (at least in the US).

We work with the DOT and ATF here in the US for explosives storage and transport. I’m sure the EU has a similar authority.

But also, not all termination systems need explosives to function…

9

I would describe my experience with gas powered systems as underwhelming.

10

It seems that I’ve found exactly the kind of solution I need:

The system looks like I would connect the FTS between the ESC and the FC, while also having the ability to independently and remotely cut off the signal being sent to the ESC. The system costs around €500.

I wonder if it would be possible to create a similar system based on the same principle, but operating on a separate receiver and radio controller, with a PWM kill switch installed between the FC and ESC.