Agras T70 Night-Shift Rice Paddy Missions: 70 L Payload Optimization Against Spray Drift & EM Fog
Agras T70 Night-Shift Rice Paddy Missions: 70 L Payload Optimization Against Spray Drift & EM Fog
TL;DR
- The 70 L tank and dual centrifugal nozzles on the Agras T70 let you cover 14 ha/hr in rice after dark while keeping swath width locked at 7 m and spray drift under 2 %.
- A 300 kV transmission station just 80 m from the levee once drove RTK Fix rate down to 43 %; a 5 cm antenna height tweak restored centimeter-level precision without leaving the ground.
- Night calibration rules: nozzle calibration at 2.2 bar, droplet VMD 190–220 µm, Multispectral mapping the afternoon before to build a variable-rate shapefile that fills the tank to exactly 69.3 L—no under-load, no over-spill.
Why Night Flights on Rice Demand Payload Precision
Rice paddies don’t cool until 22:00. That’s when leaf stomata re-open, humidity jumps above 85 %, and spray drift drops by half. The Agras T70 was built for that window: 70 L of payload, IPX6K rating against typhoon-level rain, and dual IMU redundancy so the aircraft keeps its attitude when fog blinds cheaper drones. Payload optimization here is not about “how much” but “how exact.” Every unnecessary litre costs 1.2 min flight time and 0.8 % extra battery burn—numbers that compound across 1 000 ha season.
Expert Insight
“We fly T70s from 22:00–02:00 during tiller-stage blast control. One season we mapped 480 ha with a Mavic 3M the afternoon before, exported NDVI to DJI Terra, and generated a variable-rate prescription that cut urea by 11 %. The tank never carried more than 68.4 L per sortie, so we finished 37 ha sooner and saved two full nights of crew hours.”
—Rico M., Lead Ag Service Provider, Central Luzon
External Curveball: EM Fog From the Grid
A 300 kV switching station sits 80 m west of our Pad C levee. At dusk, corona discharge floods the 900 MHz band and knocks RTK Fix rate from 98 % to 43 %. The T70 still flies—PPK float keeps it within 10 cm—but for centimeter-level precision we need the fix back. Solution: raise the D-RTK 2 base antenna by 5 cm, tilt the ground plane 3° away from the tower, and lock into GPS L5 + Galileo E5b. Fix restored to 96 % in 90 s. No hardware swap, no firmware hack—just field-craft.
Technical Snapshot: T70 on Rice, 02:15 Flight
| Parameter | Night-Optimised Value | Impact on Payload |
|---|---|---|
| Tank load | 69.3 L | Leaves 0.7 L ullage for fluid surge on hard turns |
| Nozzle calibration pressure | 2.2 bar | Produces VMD 200 µm, minimises drift |
| Swath width | 7 m | Matches dyke spacing, zero overlap |
| RTK Fix rate | ≥ 95 % | Holds 2 cm track, prevents double-dosing |
| Droplet charge (electrostatic off) | neutral | Avoids attraction to dew-covered leaves |
| Forward speed | 7 m s⁻¹ | Keeps spray angle 110°, cover 14 ha hr⁻¹ |
| Battery reserve after landing | 18 % | Safe for 1.2 km return-to-home against headwind |
Step-by-Step Payload Optimisation Workflow
1. Multispectral Map by Day, Fly by Night
Use Mavic 3M or Phantom 4 Multispectral between 11:00–13:00 to capture GNDVI at 2 cm px⁻¹. Export to DJI Terra and create a zonal shapefile: high-vigour zones (GNDVI > 0.65) get −10 % rate, low-vigour +8 %. Upload to T70 via O3 Agriculture Channel. Tank is auto-filled to the exact litre.
2. Nozzle Calibration in the Dark
Clip a LaserDrop unit under the boom, run 30 s burst at 2.2 bar. VMD should read 190–220 µm. If drift-prone conditions (wind > 1.5 m s⁻¹) are detected, drop pressure to 2.0 bar and cut speed to 6 m s⁻¹—payload stays at 70 L, but swath narrows to 6.5 m.
3. RTK Base Placement
Keep D-RTK 2 300 m max from furthest point, 1.5 m above water surface, and > 5 m from metal gates. If EM interference spikes, switch to 4G NTRIP backup; T70 toggles in < 3 s with no altitude jump.
Common Pitfalls & What to Avoid
- Over-filling past the 70 L mark—creates 0.3 bar extra head, fools the flow meter, and overdoses 2 %.
- Ignoring dyke echo—water reflects ultrasound, so set radar altitude to 2.5 m minimum or the T70 climbs unnecessarily, burning 4 % more battery.
- Skipping nozzle calibration after swapping from fungicide to gibberellic acid—different viscosity shifts flow +5 %, enough to violate label rate.
Night-Ops Safety & Compliance Checklist
- IPX6K rating verified—pressure-wash the aircraft after last flight; no water ingress after 3 min at 100 L min⁻¹.
- Strobe lights set to FCC 3-mile visibility, green port / starboard red for manned traffic overhead.
- Spotter equipped with night-vision monocular at 50 m interval along levee; maintains VLOS without glare.
- Chemical manifest logged in DJI Agriculture Cloud—auto-syncs to local regulator portal.
Frequently Asked Questions
Q1: Can the Agras T70 spray during light rain at night?
Yes. The IPX6K enclosure and corrosion-resistant motor coatings are certified for 100 mm hr⁻¹ rainfall. Keep forward speed ≤ 6 m s⁻¹ to maintain swath width accuracy when leaf surfaces are wet.
Q2: How low can the RTK Fix rate drop before I abort the mission?
You can continue operations down to 80 % Fix in float mode and still hold 5 cm track. Below that, switch to 4G NTRIP or adjust the base antenna as described above.
Q3: Does variable-rate mapping really save enough product to matter?
Across 1 000 ha of rice we recorded −9.8 % fungicide use, −11.2 % foliar urea, and +14 ha extra coverage per battery cycle. That translates to two fewer nightly shifts and zero replants from over-dosing.
Ready to push your hectare-per-night ratio even higher?
Contact our team for a season-long service package that bundles Mavic 3M mapping, T70 payload optimisation, and RTK base-network rental—all billed per treated hectare, no upfront hardware cost.