I think owls disprove that theory. If it can’t be avoided to create noise for flight then how do they do it? After all they create lift, yet somehow avoid being as noisy as an equivalent size or weight drone would.
Edit: OK, on reread this is far more snarky than is deserved. Sorry!
I get what you're saying about the noise per unit weight! Clearly nature has potential ways to improve on the technology, though I have to wonder how much development is necessary until a drone could restock my corner store at the same noise level as a van does.
Overall, my larger concern, which should have been listed first, is that delivery traffic is not the primary cause of traffic on our roads. Eliminating it won't solve our transit issues in cities.
Oh I 100% agree with your point. Using drones to deliver everyday items in dense cities is a silly idea in my opinion.
I just don't think that noise is inevitable. But I think the reasoning stands even without that assumption.
Saw saw this video the other day. Check out the drone around 13:55 regarding noise and rotor design. The whole video is worth a watch though.
The company is zipline which is mentioned in a comment above.