Large heavy lifter multicopter, as cheap as possible

[b1rdman]

Hi. I need a heavy lifter that can lift 10lb with a decent TWR for a few minutes, and I want to make it as cheap as possible within those constraints. I'm aware that cheap is relative and this will probably end up >1k on the low end. The entire purpose of this thing is to fly straight up, drop the payload, and fly straight back down. So it needs to be able to get up to altitude (2000ft ish (I'm very aware of FAA stuff)) and back down, but nothing more than that, so only needs 5 mins or so of battery life. Also the payload is NOT a bomb, it is a sensing payload with a parachute that normally deploys from a rocket but we would like to drop-test it to make sure it works correctly.

The constraints above would seem to me to converge towards 4 or 6 low KV, huge prop diameter motors- talking like 20". I'm not sure if 4 or 6 would be better but that largely depends on what suitable frames I can find which I'm not having much luck with so far. I am eyeing this: https://www.foxtechfpv.com/tarot-t960-artf-combo1.html but it doesn't seem like it would quite be able to do 10lb, and I wouldn't want to try to takeoff with too low of a TWR and crash. Maybe something similar, or even the same frame, with more motors though?

Any advice is appreciated, I've built a couple small quads but nothing approaching this size. Thanks!

 

[Mark408]

Hi. I need a heavy lifter that can lift 10lb with a decent TWR for a few minutes, and I want to make it as cheap as possible within those constraints. I'm aware that cheap is relative and this will probably end up >1k on the low end. The entire purpose of this thing is to fly straight up, drop the payload, and fly straight back down. So it needs to be able to get up to altitude (2000ft ish (I'm very aware of FAA stuff)) and back down, but nothing more than that, so only needs 5 mins or so of battery life. Also the payload is NOT a bomb, it is a sensing payload with a parachute that normally deploys from a rocket but we would like to drop-test it to make sure it works correctly.

The constraints above would seem to me to converge towards 4 or 6 low KV, huge prop diameter motors- talking like 20". I'm not sure if 4 or 6 would be better but that largely depends on what suitable frames I can find which I'm not having much luck with so far. I am eyeing this: https://www.foxtechfpv.com/tarot-t960-artf-combo1.html but it doesn't seem like it would quite be able to do 10lb, and I wouldn't want to try to takeoff with too low of a TWR and crash. Maybe something similar, or even the same frame, with more motors though?

Any advice is appreciated, I've built a couple small quads but nothing approaching this size. Thanks!

Not following FAA? I like you! Anyway, that t960 has a payload weight of 8 kg which is 17 pounds. Each motor is stated to pull 3.2 kg with the 18 inch prop. I am no expert with heavy lift multi rotors but that one seems decent.

 

[HVB79]

I know you are specifically asking for a heavy lift quad but if you want to cut the cost consider thinking more outside the box. It depends on how many times you want to drop the payload. If you need to do 50 test drops then building a dedicated drop platform makes more sense. If you just need to drop it a few times there are less expensive methods.

This is a trivial task with most high wing two seat manned airplanes. The pilot / owner gives you a ride and you throw the sensor package out the door at the correct height and location. Have to know the right people but could be totally free.

Go talk to the closest skydiving location. They love throwing things with parachutes out the door. Would be trivial for them to throw your payload out the door while climbing to jump height with a regular flight of skydivers.

 

[Piotrsko]

If you and your organization can tolerate it, there's all sort of big cheap asian "drones" on ALIBABA. I was forced to stay stateside 'murican, YMMV.

Rate of decent critical? Driving up the side of a mountain would work unless you're in Iowa.

Careflight? They are wacky and use 'choppers.