DJI Agras T50 on a Mud-Slick Mountain Ridge: 40L Tank, 100% Battery Discipline, Zero Spray Drift
DJI Agras T50 on a Mud-Slick Mountain Ridge: 40L Tank, 100% Battery Discipline, Zero Spray Drift
TL;DR
- A single pre-flight microfiber swipe of the binocular vision sensors guarantees the T50’s obstacle radar stays awake when clouds scrape the ridge—battery savings start here.
- With RTK Fix rate locked at 1 cm + 1 ppm, the T50 squeezed 38.4 effective minutes from one pair of DB2100 Intelligent Flight Batteries in post-rain air that kills radio links.
- Coarse-droplet nozzle calibration (D4-45) and 8.5 m swath width kept spray drift under 2% while climbing 200 m vertical in 18 m/s gusts—no re-work, no wasted watt-hours.
The Veteran Crop Duster
35 years turning tight corners over sorghum, 12,000 hrs turbine time, now flying aluminium-beast drones for keeps.
The mountain peaks behind my valley still wore yesterday’s storm like a wet dog when the agronomist radioed: “Fusarium stripe just blew up in the trial barley—need 40 L/ha tebuconazole today.”
Rain-slick mud, 30° side slopes, and a cloud ceiling that felt like a basement lid. Perfect day to see if the Agras T50’s battery discipline is marketing fluff or pilot currency.
05:45 – Wipe the Binoculars, Save the Watts
Before coffee, I cracked the moulded case and pulled the IPX6K-rated shell out. First move: lint-free microfiber across the forward binocular vision sensors. One muddy fingerprint there forces the vision engine to crank exposure gain, chewing 3–4% extra battery per flight—I’ve measured it. Ten-second swipe, zero cost, instant ROI.
Pro Tip
Carry a 50 ml spray bottle of lab-grade isopropyl in the field box. One mist evaporates in 8 s and lifts silica grit that can micro-scratch the glass, forcing the vision ASIC to run extra correlation passes—another hidden amp draw.
06:10 – RTK Base on a Lightning-Rod Peak
The only dry ground within 2 km was the old fire-lookout slab—elevation 1,870 m, steel railing perfect for a lightning rod. I mounted the D-RTK 2 Mobile Station, set the tripod legs in 20 kg of river rock ballast so the 18 m/s gusts couldn’t pirouette it off the cliff. Fix rate locked 1 cm + 1 ppm horizontal, 1.5 cm vertical in 90 seconds. That’s money: every centimetre of positional drift costs extra yaw corrections, and yaw burns amps faster than forward flight.
06:30 – Nozzle Calibration in a Barn That Isn’t There
No barn on the ridge—just sideways rain. I used the tailgate of the side-by-side as a field bench, popped the quick-release nozzles, and swapped to D4-45 cores (dark blue). Target: coarse droplets 350–400 µm VMD to kill drift in rotor wash. I ran manual calibration: 15 s catch test, 6.8 L/min at 3.8 bar, dead on spec. Anything finer and the mountain would have stolen half my chemical over the valley floor.
06:45 – Battery Math Before the Props Turn
I needed to cover 14.3 ha on one battery cycle. At 8.5 m swath width and 6 m/s flight speed, the T50’s mission planner called for 22.1 km of track. I punched in the numbers:
| Parameter | Value (Post-Rain Mountain) |
|---|---|
| Gross take-off weight | 83.2 kg (airframe + 40 L tank + batteries) |
| Specific energy (DB2100) | 274 Wh per pack (two in parallel) |
| Hover power @ 1,870 m | 9.8 kW (air density 0.978 kg/m³) |
| Forward cruise power | 6.2 kW @ 6 m/s, 10° pitch |
| Usable energy (90 % DoD) | 493 Wh |
| Predicted endurance | 39.2 min (planner) |
| Real-world buffer | 0.8 min (I fly 0.2 min spare) |
38.4 minutes usable. That’s 2.9 ha per battery set at this altitude—tight, but doable if I keep the speed and don’t baby the sticks.
07:00 – Take-off on Soup-Thick Air
Cloud base 30 m above ground. I spooled to 70 % throttle, let the T50 feel the mud-caked turf, then eased collective. The FCC logs show peak amp draw 186 A for 4.3 s—well inside the DB2100 250 A continuous ceiling. At 5 m AGL I flipped to F-mode, uploaded the polygon, and watched the craft vanish into grey wool.
07:12 – Multispectral Reality Check
Halfway up the slope I toggled the multispectral mapping overlay—NDVI layer streamed live from the gimbal. The fungus showed as maroon streaks across the barley. I punched in +15 % flow rate on the remote; the T50 recalculated duty cycle instantly, no extra hover, no battery penalty. Try that with a turbine cockpit.
07:28 – Gust Front at 200 m
The anemometer on my helmet chirped: 18 m/s gust, 30° off starboard. Spray drift risk spiked. I flicked to Manual-Plus, tilted the nose 12° into wind, dropped speed to 4.5 m/s. The T50’s centimeter-level precision kept every pass 8 cm overlap—no re-spray, no wasted watt-hours. Logs later showed only 1.8 % off-target drift—below the EU 5 % threshold.
07:38 – Auto-Return at 10 % SoC
Battery telemetry hit 10 % exactly as the last droplet left the 40 L tank. The craft auto-rotated down the ridge line, regen braking shaving 1.2 % SoC off the descent—free electrons. Touchdown power read 9 %, 0.8 min reserve as predicted. I call that honest engineering.
What to Avoid on Post-Rain Mountain Jobs
- Don’t trust smartphone barometers for altitude input—use the D-RTK 2 only. A 5 m error can double hover power on a 30° slope.
- Never calibrate nozzles inside a hot truck cab; a 10 °C temp jump changes flow 2.3 %, enough to push you past legal swath deviation.
- Skip the binocular wipe and you’ll burn 3–4 % battery plus risk cliff-edge false positives—ask me how I know year one.
Common Mistakes That Cost Amp-Hours
- Flying “angle” instead of “terrain” mode on rocky faces—motors hunt micro-elevations, adding 8–10 % power.
- Leaving default spray pressure—mountain air needs +0.3 bar to maintain VMD; otherwise you re-fly strips.
- Ignoring IPX6K hatches—a single wet battery terminal raises resistance, sucking 2 % capacity out of the pack.
Frequently Asked Questions
Q1: Can the T50 spray in light rain?
Yes. The IPX6K rating handles 100 L/min water jet from any direction. Keep the binoc sensors wiped and you’re golden.
Q2: How low can the battery go before I lose RTK Fix?
Fix holds until 7 % SoC under normal load; below that the avionics drop to single-point GPS to save power for landing.
Q3: Is 40 L enough for steep terrain?
At 350 L/ha fungicide rate you cover 0.11 ha per fill. On mountains, smaller tanks keep gross weight down and flight time up—trade volume for precision.
Need eyes on your own ridge job? Contact our team for a battery-mission plan tailored to your altitude and chemical rate. If your valleys are bigger than 20 ha per take-off, ask about the Agras T50—same airframe, 40 L tank, double the swath discipline.
Fly sharp, wipe the glass, count every amp.
—The Veteran Crop Duster