Inspecting Guide: Agras T100 Best Practices

META: Step-by-step field workflow for the Agras T100 when wind, dust and wildlife make every flight a gamble—learn the pre-clean ritual, drift-proof calibration and RTK hacks that keep imagery razor-sharp.

The wind is already flexing the cattails when I park the truck beside the levee. In front of me, 380 ha of wetland rice wait for their late-season health scan; above them, a pair of grey herons circles like they own the sky. My job is to prove them wrong—quietly, quickly and without a single droplet leaving the plot. The Agras T100 can do that, but only if you treat the pre-flight minute like a surgeon treats the scalpel. Miss one wipe and the whole mission becomes a blurry waste of battery.

Here is the exact choreography I run in the field, distilled from three seasons mapping reed beds and wind-battered maize from Hubei to the Sacramento Delta. Copy it, adapt it, ignore it at your peril.

1. Strip it, rinse it, trust it

Before the props even come out of the case, I unscrew the orange quick-release nozzles and drop them in a 200 ml squeeze bottle filled with distilled water. Five shakes, one firm tap on the rim, then a visual check through the swirl chamber. A single crystal of dried surfactant will throw your VMD (volume median diameter) off by 30 µm; in a 12 m/s gust that translates into 1.2 m extra drift. While the parts drip-dry, I run a micro-fiber cloth along the underside of each arm, hunting for the invisible film of silicone that field crews sometimes leave after a foam decontamination. The cloth should glide; if it stutters, hit the spot with 70 % isopropyl.

Why the fuss? Because the T100’s coaxial downward radar compares the dielectric signature of the boom against the ground. A film of oil changes the reflected wave just enough to nudge the flight controller into believing the aircraft is 3 cm higher than reality. You will not notice in open sky, but when you hug a 2 m sorghum canopy that offset puts the lens inside the plants instead of above them.

2. Calibrate for wind you can feel in your collar

The T100 ships with four sets of swirl discs: red 110-02, yellow 110-03, blue 110-04 and the new 110-05 that DJI quietly added last spring. Most operators run the 03 because it feels middle-of-the-road. Feel is irrelevant; numbers rule. I punch the day’s temperature, humidity and the forecast gust into the drift calculator buried in the Agras app’s service menu, then pick the disc that keeps Dv0.5 under 180 µm at 6 bar. Yesterday that meant stepping down to the 02, cutting swath from 9 m to 7.2 m and adding two extra passes. Net result: zero off-target deposition on the sensitive bulrush buffer, confirmed by a strip of water-sensitive paper clipped to a reed at the field edge.

3. RTK fixation: the 30-second gate

Wetlands eat GNSS for breakfast. Water reflects the signal, reeds scatter it, and the base station 8 km away on the county firehouse roof is already working through a forest of cranes in the port. I learned the hard way that “Float” is not good enough when you need centimetre-level repeatability for multi-spectral indexing. The fix rate must hit 99 % before I arm the motors. My workaround is a 30-second static soak: power on, props off, hold the T100 at shoulder height and slowly rotate 360° while watching the LED bar. If the bar flashes red even once, I walk 15 m toward the levee—usually that puts me above the water table shadow—and repeat. Average time lost: 47 seconds. Time saved by not re-flying because the orthomosaic shifted 12 cm: three hours.

4. Wildlife protocol: the heron test

Birds hate surprises, and a 50 kg octocopter at 15 m sounds like a swarm of mechanical hornets. I start with a stationary hover at 25 m for exactly 60 seconds. If the herons keep fishing, I drop to survey height. If they flare, I climb and wait. Patience is cheaper than explaining to the reserve warden why a crane colony abandoned the rookery. On one job the pause cost me 8 % battery, but it saved the entire season’s permit.

5. Multispectral timing: the 30-minute window

The T100’s gimbal bay accepts the P4 Multispectral payload with two clicks, yet the magic only happens when the sun angle sits between 35° and 45°. Below 35° the NDVI curve flattens; above 45° the canopy starts to glitter and your red edge band washes out. I run the math the evening before and set a 30-minute take-off window. Wind usually peaks right after sunrise in this valley, so I aim for the first third of the slot. Yesterday that meant wheels up at 08:12; by 08:43 I had 92 % coverage before the gust sensor tripped at 14 m/s.

6. Swath math in rolling terrain

The official manual claims 11 m spacing at 3 m AGL. On paper that is fine; in a rice paddy whose dykes create 40 cm micro-cliffs, the outer nozzles lose 0.3 bar of pressure climbing the slope and gain 0.2 bar dropping off it. I map the field with the drone first, export the DSM, then import it into QGIS and split the plot into 2 % grade zones. Each zone gets its own flight plan with adjusted speed: 4.5 m/s for uphill legs, 5.8 m/s downhill. The result is a coefficient of variation under 7 % across 52 validation cups—low enough that the agronomist stops asking if the data are “spray-drift artefacts.”

7. Post-flight rinse: IPX6K is not a licence to procrastinate

The T100 carries the highest wash-down rating of any Agras, but IPX6K means the casing survives pressurised water, not that chemistry enjoys marinating overnight. I land, pull the battery, and hit the arms with a low-pressure hose before the potassium suspension dries to concrete. Two minutes now, or twenty minutes with a brass brush later—your call.

8. Data hand-off: from drone to decision

Back at the truck I pop the micro-SD and slide it into a rugged tablet. The raw six-band stack is 4.7 GB; I run a quick linear stretch, export the NDVI, and drop a shapefile of the low-vigour zones into the shared drive before the farmer finishes his coffee. He opens the file on his phone, zooms to the southwest corner, and points at a 0.3 ha blotch. “That’s where the geese camped last week,” he says. We convert the polygon to a UTM grid, feed it back into the T100, and set a spot-spray mission for the following dawn. Total lag from landing to prescription: 11 minutes.

9. The spare-parts pouch nobody packs

I keep a film canister (remember those?) filled with silicone O-rings, a 1.5 mm hex key, and a folded strip of 600-grit sandpaper. The hex key adjusts the nozzle collar when the spray angle drifts; the sandpaper flushes a nick out of the swirl disc in 30 seconds; the O-rings replace the ones you inevitably slice while re-assembly races the sunset. The whole kit weighs 38 g and has saved four missions this year alone.

10. Know when to walk away

Wind gusts are forecast to spike past 17 m/s by noon. I still have 46 % battery and two more blocks on the flight plan. The farmer asks if we can “push it.” I show him the yellow line on the controller: above 15 m/s the T100 automatically throttles back to 3 m/s ground speed to maintain attitude, turning a 12-minute lap into 24 and eating the rest of the charge. He nods; we land. The herons keep fishing, the bulrush stays clean, and the data stay sharp. That is what professionalism looks like—measured not by how many acres you finish, but by how few you have to re-do.

If you want the checklist as a laminated field card or need a second pair of eyes on your nozzle math, message me through this WhatsApp thread—I usually answer while the batteries are cycling.

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