Overhead visibility · Manna UAV Naked-eye estimate

Overhead, it’s about the size of the moon.

Even at the top of the 50–80 m band these drones fly, the white body covers about as much sky as the full moon — a pale shape the eye catches, especially once it moves. And you tend to hear it before you see it: the sound carries far enough that it reaches you well before the drone is overhead.

Fig. 01 — Apparent size, against the full moon

Apparent width, drone directly overhead
Height overhead	Apparent ∅	vs moon
50 m	48′	1.5×
60 m	40′	1.3×
70 m	34′	1.1×
80 m	30′	1.0×
90 m	27′	0.9×
100 m	24′	0.8×
110 m	22′	0.7×
120 m	20′	0.65×
Full moon	31′	1.0×

Each ring is the drone’s apparent width at that straight-line distance overhead, drawn to scale. The dashed ring is the full moon (31′), for comparison. Based on a white body roughly 0.7 m across; the wider rotor span (~1.3 m) would be about double these sizes. Arcminutes (′) are sixtieths of a degree.

Big enough to see — at every height.

Across this whole band the body subtends roughly 20 to 48 arcminutes — somewhere between two-thirds of the moon and one-and-a-half moons. Angular size is simply never the limit here: if you look straight up at it, you will see a distinct pale object from 50 m all the way to 120 m. What shrinks with height is not whether you can see it, but how much of its shape you can make out.

Seeing it as a drone.

Telling that it’s a multirotor — separate arms, four coaxial rotors — needs finer detail, down near the eye’s one-arcminute limit. That holds up to about 90–100 m. Beyond that the structure blurs together and it reads as a featureless dot or a short pale dash drifting across the sky.

Fig. 02 — The same drone, two skies

Clear sky

Bright overcast

Same drone, same height. Against blue the white body stands out sharply; against bright overcast the contrast is softer — but its size on the sky is unchanged, and a moving object still draws the eye. And either way, you will usually have heard it first.

Why it catches the eye.

A moving object overhead

Against blue or a darker backdrop the white body stands out plainly; against bright overcast the contrast is softer — but it is moving, and movement is exactly what the eye is built to catch.

Movement & glint

The eye snaps to motion, and spinning rotors throw intermittent flashes. A moving drone is caught far more readily than these still figures suggest — it’s usually what makes people look up.

Whether you’re looking

A speck you’re watching for is easy to hold; one you weren’t expecting is easier to overlook as height grows. But within the 50–80 m band these fly it stays a moon‑sized shape — and its movement keeps giving it away.

You hear it before you see it.

Even when the drone is only a small dot — off to one side, or against bright cloud — it has rarely arrived unannounced. Sound spreads outward in every direction and travels much further than the eye can pick the aircraft out: from the measured cruise level, a passing drone stays audible somewhere on the order of 100–300 m away, depending on how quiet your surroundings are. The noise reaches you first, and you look up to find it — it is a presence to two senses, not one.

And the quoted height is MSL — above sea level, not above your roof. Manna’s ~50–80 m is measured from the sea, so over raised ground you subtract your local elevation: where the ground sits 30 m above the sea, “80 m MSL” is only about 50 m over your head — closer, larger and easier to see than the figure sounds.

Method

Apparent size = body ÷ distance (small-angle), in arcminutes. Body taken as ~0.7 m across the long axis of the white fuselage; rotor-tip span ~1.3 m. Naked-eye detail limit ≈ 1′; full moon ≈ 31′.

How to read it

Overhead = best case; off to the side the slant distance is greater and the disc shrinks. Heights shown are straight-line distance overhead. Manna’s altitude is quoted MSL (above sea level), so subtract your local ground elevation to get the height above you.

What this is

A naked-eye size-and-contrast estimate, not a guarantee of detection. Fuselage size is read from the manufacturer drawing’s proportions, which dimension the rotor span, not the body. The audible range is an estimate from the measured 59 dBA cruise level (TCD, 2024) and ordinary sound spreading — it reaches further in quiet conditions and less against busy daytime background.