>> Zigzagging through a forest

At speeds of up to 40kmh, the claim was 100mph+

>> The alleyways are a simpler version

Here's the video of that https://www.youtube.com/watch?v=Lr7L2t-svJQ&t=16s - that's below 5mph and carrying an external payload of 0 grams, and the reason it's in a forest is because you can't fit them all in an alleyway and you need multiple in order for them to work.

>> Here is a YouTube video of a demonstration with a hexcopter

At 22mph, the claim was 100mph+

>> And here is a dude flying a DJI Inspire

At around 20 mph max but mostly hovering and for 8 minutes at that before running out of juice

>> Folks have been using those

No. People like yourself can easily dream this concept. It stands to reason, why wouldn't it be possible? The truth is that battery technology is no where near good enough yet.

It's the first idea tried in Syria, it's been tried thousands of times at this point and yet we have more documented cases of the aggressors killing or injuring themselves than of the 3 documented cases where this actually worked in practice - all 3 of which i think everyone can agree from the footage are pure fluke. Zero aiming was possible, it was just release and hope for the best in all 3 cases.

What people are actually using them for is for recon and aiming of artillery. They're effective in these roles and that's why they're used for this rather than strapping heavy explosives to them.

>> autonomous flight is harder with smaller drones (less computing payload available

That's not true. Compute isn't a restriction in small drone autonomy. A basic F4 is wayyyyy overkill for flight stability and control. Waypoint navigation is even lower power requirements since it amounts to a simple loop not much more complex than:

1. Get current GPS coordinates
2. Get current compass heading
3. Send directional input via serial peripheral to F3 or F4 flight controller
4. Repeat

The flight controller is doing far more processing than this - gyro input & smoothing for each of 3 axes, accelerometer (same), GPS location at approx 10Hz, optionally barometric input (rare and usually not necessary). These inputs are often processed through kalmann filter before finally calculating the torque command to issue to each ESC's microcontroller. This only happens at up to a few hundred Hz so you can see compute power is not a restriction.

In larger aircraft it's harder because you can't beat physics, in a small drone i can change the amount of torque applied to a propeller 4+ times per rotation in toy off the shelf drone tech today. With larger craft that have non-electric motors this is simply not possible. You can't instruct a mechanical engine to regulate its power output with the same fidelity of an electric motor.

>> worse sensors

The only required input sensor is a gyro - in practice we use accelerometers and GPS in autonomous drones but there are ways of avoiding the need for these (e.g. visual inputs / optical flow as a correction for drift). MEMS gyros are cheap and effective, what better sensors do you need?

Your reasoning is uninformed / dreamed up based on watching too many movies and not being familiar with the actual discipline.

Better algorithms are a restriction. The science / theory part of implementation was achieved by all projects fairly quickly (ardupilot, clean/betaflight, etc. etc.) - but the art part, the how it feels and performs in practice, is an unsolved problem under continual development.

>> drop Grenades

Too heavy given current battery technology and lack of aiming. These are not effective weapons which is why they have limited success. More people have been killed in war zones in the past decade by garden spades than toy / photo drones with explosives.

TL;DR until batteries technology moves forward by a few generations, the concept of a small drone as an offensive weapon will not be better than that offered by something like the switchblade drone. Which when you cut through the excitment, is less valuable than conventional weaponry in most fight scenarios.