IrishSights said:
PhantomFanatic said:
After more thought, a parachute would be easy to attach. The packed chute goes on top (obviously!) and you could use Velcro straps to wrap around each arm, close to the center body.
This is a cool idea, however there are many challenges to overcome to be realistic. The placement of the chute on top is not a great idea. Do you not think that putting it on top would reduce the receiving ability if the GPS which is right underneath and crucial...unless you fly all the time in ATTI mode? Would it fit physically? you have 115mm between the prop tips less clearance. Would it affect the flow of air from the props?
I don't believe so. What will be on top is a small nylon parachute with parachute cords, also nylon. Fabric won't interfere with GPS satellite signals. The packed parachute, containing nylon cords, won't be even close to the rotors so it won't affect airflow. The electronics would be underneath or inside the drone.
Another suggestion: I've employed this a lot when I need a relay to cut a lot of current, but relays with that rating are too big. Use a multiple pole 12VDC relay. Let's say that it has six A and six B contacts. (Just in case you don't know, A are contacts that are open when the relay is NOT energized. B contacts are closed with the relay unenergized.
You have two options, but I recommend one. Wire all four A contacts in series. Make sure the ratings for each contact, times four will be the amperage you need to disconnect, plus a wide margin.
Wire the main battery to the coil of this relay. When the relay is energized, you have power to everything. Wire up the chute up to a B contact. When the relay is de-energized, all drone power will be disconnected. Your B contact will close when the relay is de-energized. This will activate the chute. You can install a small and light timer (or build one) that will give you the delay to have enough airflow for the chute to inflate.
This is a fail safe system. Say there is a massive failure and your main power totally drops out. Since the relay was energized, the power outage will make it unenergized. This closes that B contact and your chute will deploy with no action needed on your part.
Of course, you will need a small battery to run your system and chute.
Now, you may wonder how to activate the chute yourself. Use the same type 12VDC relay. Use all B contacts from it., in series with the A contacts from the other relay. Wire the power (from your second battery) from your second receiver to this relay. Your chute activating signal will energize your second relay. When activated, your B contacts will open, disrupting current to the motors.
Now, use an A contact from the second relay and wire it to the chute activation system. A schematic will make a lot more sense! I could draw one, photograph it and PM it to you or post here. Your choice.
The bottom line: A B contact from the first relay triggers chute deploying, from a power failure from the main battery. Your chute deploying signal also sends power (both using power from your second battery) to the same electrical point.
You will have a system that say if you have a fly away with RTH not working. Let's say your drone flys until the battery gets low enough to de-energize the first relay, activating the chute. Or, you send a signal to activate the chute. Either way, have a GPS tracker on-board.
The auto-deploy system, could be enough for many. Consider this patent applied for!