Hey everyone, I’m pretty new to building quads and I’m trying to make one for indoor use that can carry a heavier load, about 1.5kg. I’m not looking for anything super fast or agile, just something that moves around and can carry this weight. I’m okay with short flight times, maybe around 5 minutes.
I’m considering 5-7 inch quads with the following motors:
Brotherhobby - 2507, 1500 KV with 7" props, 6S - claims 2.13kg max thrust, or with 6" props, 6S - 2.04kg max thrust
I’ve done some basic calculations and the total weight should be around 2.5kg, with a thrust of around 8kg.
Here’s the rough breakdown:
4 motors at 40g each = 160g
Frame, ESCs, flight controller = ~250g
Battery = ~500g
Payload = 1500g
Total = around 2.5kg
With some room for error, that’s about 35-40% of the max thrust.
Would this setup work for my needs? What should I be considering when choosing between a 5" 4S setup or a 7" 6S? Is one more efficient or are there other things I need to think about?
Also, if this isn’t enough, do I need to move up to an 8-10" quad? I’d rather avoid it since that seems a bit scary!
Leith said:
Can you tell us a bit more about what exactly you’re trying to achieve? It’ll help us give you more focused advice.
Sure, I’m working on a sensor package that weighs about 1kg. It’s for indoor mapping, so the quad will be flying around confined spaces to create high-quality maps.
A 4S 5-inch setup won’t cut it. A 7-inch might work if you use an X8 configuration. You want the drone to hover around half throttle, which means you’ll need around 5kg of thrust to make it work well.
Amar said:
A 4S 5-inch setup won’t cut it. A 7-inch might work if you use an X8 configuration. You want the drone to hover around half throttle, which means you’ll need around 5kg of thrust to make it work well.
I thought I was good with around a 2:1 thrust-to-weight ratio (2.5kg weight, 8kg thrust)? Am I missing something?
Amar said:
A 4S 5-inch setup won’t cut it. A 7-inch might work if you use an X8 configuration. You want the drone to hover around half throttle, which means you’ll need around 5kg of thrust to make it work well.
I thought I was good with around a 2:1 thrust-to-weight ratio (2.5kg weight, 8kg thrust)? Am I missing something?
The problem is that 8kg is your max thrust. Based on the specs, the 2507 motors won’t lift the drone until you hit around 75-80% throttle, which will hurt your flight time, control, and might even overwork the motors.
I’d suggest going with a 6S 7-inch setup. Something like the Eco Max II 2807 1300kv motors and 7-inch props would do the job nicely. You can always adjust with similar motors if needed.
In that case, you want slow and steady performance, which usually means bigger props and lower RPM. So, a 7-inch over a 6-inch, or even an 8-inch over a 7-inch, with motors in the 2806 to 2808 range, running 1100 to 1300kv. Lower RPM will also help reduce vibrations. For the best results, make sure you balance the props, especially for detailed scanning work.