UAS architecture

Example 1 Which subsystem is most connected?

from itertools import combinations

subsystems = ["air vehicle", "payload", "C2 link", "GCS", "launch & recovery"]
interfaces = {
    ("air vehicle", "payload"): "power, data, mount",
    ("air vehicle", "C2 link"): "telemetry",
    ("payload", "C2 link"): "video",
    ("C2 link", "GCS"): "commands, status",
    ("air vehicle", "launch & recovery"): "mount, charging",
    ("payload", "GCS"): "imagery, data",
}
n = len(subsystems)
possible = len(list(combinations(subsystems, 2)))
print(f"{len(interfaces)} of {possible} possible pairs are used (n(n-1)/2 = {n * (n - 1) // 2})")
degree = {s: sum(s in pair for pair in interfaces) for s in subsystems}
for s, d in sorted(degree.items(), key=lambda kv: -kv[1]):
    print(f"{s:<18} {d} interfaces")
changed = "C2 link"
retest = sorted({x for pair in interfaces if changed in pair for x in pair} - {changed})
print(f"if the {changed} is replaced, retest the interfaces with: {', '.join(retest)}")

6 of 10 possible pairs are used (n(n-1)/2 = 10)
air vehicle        3 interfaces
payload            3 interfaces
C2 link            3 interfaces
GCS                2 interfaces
launch & recovery  1 interfaces
if the C2 link is replaced, retest the interfaces with: GCS, air vehicle, payload

The air vehicle, payload and C2 link each have three interfaces, the most of any subsystem. These are where a change has the widest effect. For example, replacing the C2 radio means retesting its interfaces with every connected subsystem, not just the radio itself.

Example 2 Classifying systems on the market under three frameworks

KG_LB, M_FT, MS_KT = 2.20462, 3.28084, 1.94384
DOD = [(1, 20, 1200, 100), (2, 55, 3500, 250), (3, 1320, 18000, 250), (4, float("inf"), 18000, float("inf"))]

def dod_group(kg, alt_m, speed_ms):
    lb, ft, kt = kg * KG_LB, alt_m * M_FT, speed_ms * MS_KT
    for g, max_lb, max_ft, max_kt in DOD:
        if lb <= max_lb and ft < max_ft and kt < max_kt:
            return g
    return 5

def easa_class(kg):                       # by mass only; real classes have other requirements too
    for limit, c in ((0.25, "C0"), (0.9, "C1"), (4, "C2"), (25, "C3/C4")):
        if kg < limit:
            return c
    return "not open category"

def thai_rule(kg, camera):
    if kg > 25:
        return "separate regulation (> 25 kg)"
    return "must register" if camera or kg > 2 else "no registration"

systems = [   # name, mass kg, operating altitude m, speed m/s, camera
    ("mini quad", 0.85, 90, 15, True),
    ("mapping VTOL", 3.6, 90, 16, True),
    ("long-range fixed-wing", 20, 1500, 30, True),
    ("spraying drone (full tank)", 42, 10, 7, False),
]
for name, kg, alt, v, cam in systems:
    print(f"{name:<27} DoD Group {dod_group(kg, alt, v)} | EASA {easa_class(kg):<17} | Thailand: {thai_rule(kg, cam)}")

mini quad                   DoD Group 1 | EASA C1                | Thailand: must register
mapping VTOL                DoD Group 1 | EASA C2                | Thailand: must register
long-range fixed-wing       DoD Group 3 | EASA C3/C4             | Thailand: must register
spraying drone (full tank)  DoD Group 3 | EASA not open category | Thailand: separate regulation (> 25 kg)

The spraying drone with a full tank exceeds 25 kg, so it falls under the separate notification, and it is Group 3 in the US framework even though it flies low and slowly, because it weighs more than 55 lb. The long-range fixed-wing weighs 44 lb, within the Group 2 weight limit, but flies at about 4,900 ft, above 3,500 ft, so it is Group 3; in Europe it would not be in the open category at that height even though its mass fits class C3/C4. The actual take-off mass including payload decides the class, not the empty mass.