Ballistic UAV

A project log for Silly hardware wishlist

Too simple for a project page & which may never happen.

lion-mclionheadlion mclionhead 06/01/2023 at 07:130 Comments

An idea which has occasionally come & gone is a ballistic UAV which goes up to a predetermined altitude, gets a picture, & passively falls.  In lion use, the mane quad copter mission was just straight up to 400ft, 360 deg panorama, & straight down.  It ended up being quite a waste of hardware for just that.

This mission profile covers the needs of photographing real estate, selfies, photogrammetry, but is useless for gootube vijeos.  It might be clandestine enough to sneak into places where quad copters aren't allowed.

Still, the ideal vehicle evolved from quad copters to a really compact analog of a rocket or a mortar.  It would be rapidly reusable, which would make it electric.  It would be compact, which would make it a ducted fan. 

A big question is if it would actively keep its position.  This would have to be determined experimentally.  If it was aerodynamic enough to be unaffected by wind & stayed low enough, it wouldn't need guidance.  To have a gentle enough acceleration & go high, it probably would need GPS guidance.  A selfie cam could be passive. 

They would all need a barometer for altitude sensing.  The self propelled system would lift off, hover at the prescribed position for just long enough to get an exposure, & descend.

A very compact selfie cam could be an EDF with torque fins. 

It could be kinetic & launched by a slingshot or trebuchet.  The unpowered, kinetic system would be the initial design since it's the simplest.  The self propelled mode would put less stress on the payload, but the kinetic system could be flown where powered vehicles aren't allowed. 

It would need fins to prevent rotation.  Maybe it could be a lifting body which defeated roll.

The kinetic system would be the smallest & have the biggest advantages over a quad copter.  It would not be easy to control the kinetic system's target altitude.  The acceleration would have to be controlled somehow.  It would need torque fins to manetain a constant heading. 

The trick is keeping it stationary long enough to get an exposure.  This depends on the camera's sensitivity.  It could fly straight through the target altitude & constantly shoot pictures.  It could just use an accelerometer to detect the lowest speed & shoot pictures then.

The leading camera idea is a 360 cam pointing down.  Otherwise, it would be a wide angle cam pointing down & sideways.  The 360 cam could get away with less roll authority, but it requires a big lens & it dictates the bottom of the lifting body.  A really fast wide angle cam could spin slowly to get a 360 image.

For a selfie, it would have to be fired by remote control so the operator could insure it was aimed the right way.  The landing would be difficult, since it would smash the camera lens.  A parachute or some kind of cage enclosure seems necessary.   Maybe antennas could deploy.

A starting point would be passive lifting bodies which manetained their orientation through all phases of flight.