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The tail hook grab is actually the method that fighter jets use to land on aircraft carriers. Same with using a rail to launch the plane.

> but landing it by catching it using a small hook at the tail of the plane isn't that common I presume.

Been used by the Navy since 1911.

https://en.wikipedia.org/wiki/Arresting_gear

Gas powered model engines are not that unreliable, even for model airplanes. One made it all the way across the atlantic: https://amablog.modelaircraft.org/amamuseum/2017/03/29/trans...

Ok, the first 4 were lost but this is a huge journey with limited fuel and bad weather. And navigation was a problem too.

The big benefit of gas powered in larger vehicles is both the easy fast refueling and the higher energy density of fuel. Combustion engines for model airplanes are heavier than their electric counterparts because you can only scale things down so much, you still need to contain a constant fire and the associated pressure.

And in this usecase the slow recharge isn't really an issue anyway. It also makes sense for marketing reasons, being 'green'. Even though if fuel were used, you could probably run this entire company for a year on the fuel a semi truck would burn to drive 100km :) I don't think it would be a bad thing for the environment if a company like this would use fossil fuel, it's still a lot less wasteful than the alternatives.

I doubt slow recharge is even an issue since they can just pop in a new charged battery pack and put the depleted one on a charger. With swappable battery packs a drone can be relaunched within minutes.

> Gas powered model engines are not that unreliable, even for model airplanes.

Still incomparable to any other option. Having 1 in 1000 crash chance will disqualify it as a DHL alternative.

Putting 2 of them on the drone will surely make it cost more than $500

And putting even the cheapest turbine on it is out of question, unless you talk about toy turbines that are as unreliable as RC piston motors.

I wonder if a pulse jet (as used on the V-1) would be an option?

I've seen hobbyist level plans for them, and a pulsejet requires zero moving parts, so reliability should be excellent. The geometry of the engine does all the work.

> pulsejet requires zero moving parts, so reliability should be excellent.

Valves, and pumps are moving parts too.

Modern pulsejets don't use valves.

https://en.wikipedia.org/wiki/Valveless_pulsejet

Fuel can be either gravity fed or possibly a pressurized system (e.g. fill the deadspace in the tanks with compressed nitrogen)

> landing it by catching it using a small hook at the tail of the plane isn't that common I presume.

A lot of military drones have a hook at the end of one wing, and they hang a vertical wire under tension from a boom arm, with a differential gps receiver at the top of the wire. Ends up it's all accurate enough for the drone to catch the wire. I presume zipline went with their more complex approach as wings strong enough to just snag and stop would be past their weight limits.

> That sounds like an unfair comparison, a more accurate comparison would have been to gas powered drones.

It's a comparison for customers, showcasing the difference between zipline's solution (electric drones) and the existing solution (gas trucks) to the problem zipline is trying to solve (medical logistics). If gas drones or electric trucks were to enter the space then it should be updated.