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Comment by JumpCrisscross | Hacker News Reader

Single-use also dramatically expands the envelope of workable chemistries.

One-way travel also at least doubles effective range, which increases the targetable area by a the square.

For battery-powered craft, where there's no appreciable reduction in propellent mass over the course of the flight, this is a direct scaling. For fuel-based craft (which I'm surprised are not more heavily used), the fuel mass falls as it's consumed, such that the effective net mass is somewhat less than 1/2 the total launch fuel load (less fuel mass -> less lift and drag load).

In the extreme case, ballistic missiles consume virtually their entire fuel load early in the flight ("boost phase"). Cruise missiles / drones might fly to a higher altitude and glide to their targets. Even battery-powered drones might jettison their primary battery (retaining a small navigation power source) and glide to targets by first climbing to a high altitude.

Another option is solar-powered (or assisted) drones, which for small payloads (most especially surveillance, though directed weapons / shaped charges would be another option) could achieve long ranges, high loiter times, or both.

> where there's no appreciable reduction in propellent mass over the course of the flight

Staging?

As in: drop spent batteries? That would require another mechanism that can fail.

More common seems to be use of a launch system of a catapult or slingshot, where early-phase acceleration is provided by ground-based infrasturcture. This can be extremely basic, e.g., surgical tubing and a support framework. The Zipline drone-based delivery system utilises this, as well as parachute-based drops (its payloads, unlike those of the Ukrainian drones, are presumed to be shock-sensitive), and a dragline-based capture mechanism (not required for one-way flight missions). Zipline's catapult accelerates the drone from 0 to 60 kph in 0.3s: <https://yewtu.be/watch?v=jEbRVNxL44c&t=3m50s).

Those drones, incidentally, have a 6 kg payload capacity and 160 km range (one-way).

But yes, staging or jettisonable batteries might be another option, at an increased complexity cost.

and if you can consider lipo batteries to be dispensable, you can over-discharge them, to extract a lot more capacity. It destroy the cells for resuablity, but you can get waay more Watt.hours from them.

Indeed, zinc air batteries (used in hearing aids) are more energy dense than lithium ion, and are cheap. Lithium air would be much better again (close to gasoline) but a harder material to work with, and more expensive.

Metal-air batteries have the somewhat unusual property of gaining mass as they discharge (they fix oxygen from the air). How significant that mass gain is I'm uncertain of, but it confounds the diminished-mass-with-flight logic of fuel-based powerplants.

In one-way drones for once the less nice properties of Lithium Ion batteries would be an advantage.

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