[aprssig] FW: APRS Question (Drone tracking of downed balloons)

[Stephen H. Smith]

On 6/11/2020 2:28 PM, Robert Bruninga wrote:
> Kameron KG7VSN asked a question about using a RC aircraft to act as a final 
> digi for a balloon once it has landed.  But I’d take it one step further.
> 
> Put the APRS digipeater on a drone and also listen for the LAT/LON of the 
> balloon.  Then launch the drone once the balloon begins to descend.  Program 
> the drone to always go to the balloon position and maintain 1000 feet altitude 
> until told otherwise.  (or whatever is the legal height for drones…)
> 
> 

Maximum legal height for civilian-type drones is only 400 feet AGL.  More 
importantly, you have to maintain visual contact with the drone at all times; 
i.e. you can't send it many miles away from your own control point.

The real question is how would you mount a digi on a drone?
The average consumer drone has next to no additional lifting capacity. Like a 
space rocket where 80+ percent of the liftoff weight is fuel, about 2/3rds of 
the weight of the typical drone is battery pack. I have been thinking about 
putting a Big Red Bee APRS tracker on my Autel EVO which would be less than an 
ounce added weight.

But an APRS digi would require a full TX/RX radio, a TNC-like device of some 
sort sor and a battery system.  Maybe one of those discontinued Alinco 
credit-card-sized QRP 2-meter rigs and a TT4....

Most serious consumer drones (DJI, Autel, Parrot, etc) are powered by 
proprietary lithium-ion battery packs with odd voltage outputs. One might also 
have to factor in some sort of DC-to-DC converter if you want to steal power 
from the drone's own battery pack.   Note that the maximum run time for most of 
these drones on a fully-charged battery is 15-25 minutes max, even before you 
start sucking power from the battery pack for other electronic devices.  Due to 
the limited flight time, ou would have to launch the chase drone very close to 
the end of a balloon flight, just before landing.


Note that the drone already has TWO radio systems on board.  One for flight 
control and camera control uplink and engineering data (battery state, 
altitude, GPS data, etc) downlink.  A separate radio provides the live HD or 
UHD video feed down link.  One would have to thoroughly test the EMI/RFI issues 
before putting a third 2M VHF transmitter onboard.

___________________________________________________________
Stephen H. Smith    wa8lmf (at) aol.com
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