Agras T50 at 3000 m: How 40 L Precision Spraying Defeats Cliffs, Cross-Winds & a Rogue Radio Tower

TL;DR

The 40 L Agras T50 maintains centimeter-level precision above the tree-line by fusing RTK Fix rate ≥ 99 % with a 360° spherical radar—no manual height chasing required.
A 5-second antenna-angle tweak neutralised unexpected EMI from a mountaintop relay station, keeping the uplink at -60 dBm and spray drift within < 1 m even in 25 km h⁻¹ ridge lift.
Swath-width sweet spot at 7 m (coarse droplets, 250 µm) delivers 98 % canopy penetration on 35° slopes while cutting water use 18 % versus traditional downhill run-off spraying.

Why Mountain Peaks Rewrite the Rulebook

Above 3000 m, air density drops 25 %, gusts spike without warning, and every rock face becomes a potential reflector for both spray drift and radio interference. Standard valley settings—flat terrain, stable signal, calm air—no longer apply. The Agras T50 enters this arena with three non-negotiables:

Spherical obstacle radar (front, rear, top, bottom) refreshed at 100 Hz.
Dual-antenna RTK + GNSS module rated for 50 000 m altitude firmware ceiling.
IPX6K wash-down housing so summit sleet or blown dust cannot ingress.

Yet even hero specs bow to physics when a military telemetry mast starts pulsing 50 W on 1.5 GHz, exactly one channel away from your control link. Below we break down what happened, how the T50 countered, and the exact checklist we now hand every ag-service crew before they climb.

Field Event: The Rogue Tower That Steered Droplets

Site: 40 ha of high-value walnut on a 32° southwest face, 3150 m, Peruvian Andes.
Mission: Late-season copper + boron boost, 30 L ha⁻¹, wind 12 km h⁻¹ gusting 25 km h⁻¹.

Minute 7: RTK Fix rate flicked from 99.2 % to float, then DGPS. Obstacle radar still green, but spray drift footprint widened from 0.8 m to 2.3 m—unacceptable above sensitive cloud-forest understory.
Root cause: Line-of-sight to a radio repeater 1.2 km away generated -42 dBm interference at the aircraft.
Fix: Remote pilot rotated upper antenna from 0° (horizontal) to 45° perpendicular to interference source; signal strength recovered to -60 dBm, RTK re-fixed in 8 s, and droplet spread returned to spec. Total downtime: 45 s.

Pro Tip: Always perform a 5-second spectrum sweep with a handheld RF meter before the first tank. Interference above -50 dBm within ±20 MHz of your frequency band warrants an antenna re-orient or a 500 m offset flight corridor. The T50’s aluminium-shielded comm box gives you 12 dB of extra link margin—use it.

Head-to-Head: T50 vs. Traditional Manned Mist-Blower on Alpine Terrain

Metric	Agras T50	Manned Mist-Blower
Tank capacity	40 L	600 L
Operational altitude ceiling	5000 m (factory limit)	2500 m (engine derate)
Swath width on 30° slope	5–9 m (nozzle-calibration dependent)	15 m (drift prone)
Pass spacing accuracy	≤ 2.5 cm RTK	≥ 30 cm manual flagging
Spray drift (D[v0.5] 250 µm)	< 1 m	3–7 m
Water volume per ha	30 L	200 L
Refill cycle on ridge	3 min (portable bladder)	45 min (downhill shuttle)
Daily output (steep orchard)	24 ha	8 ha

Bottom line: one T50 crew of two finishes the ridge three hours faster, uses 18 % less active ingredient, and eliminates the soil-compaction risk of a 3 t tractor on switch-backs.

Calibrating for Thin Air: Nozzle, Pressure & Droplet Survival

Air density at 3000 m shears droplets 15 % faster than at sea level. Counteract with:

Nozzle calibration: Swap yellow (110 µm) for blue (250 µm) when wind > 20 km h⁻¹; increases momentum 2.3× and halves drift distance.
Pressure sweet spot: 2.2 bar yields D[v0.5] = 245 µm while staying within IPX6K seal limits.
Swath width: Reduce from default 9 m to 7 m; overlap remains 5 cm thanks to RTK, but canopy impact energy rises 18 %.

Log these parameters in the T50’s multispectral mapping tab; the aircraft auto-adjusts flow rate (0.4–6 L min⁻¹) to maintain ±3 % of target dose even when slope angle changes 8° mid-row.

Common Pitfalls & How to Dodge Them

Launching with a partial RTK fix
Float mode looks tempting when satellites dip to 16—don’t. Drift error jumps to 30 cm, enough to slam a rotor into a 40 cm pine outlier. Wait for Fix or shift base station 200 m upslope.
Ignoring thermal lift
Morning sun on east-facing rock creates 3 m s⁻¹ updrafts. They feel like “free altitude” until the aircraft crests the ridge and sinks 8 m in 2 s. Set obstacle buffer to 10 m above canopy instead of default 5 m.
Under-lidding the tank
At 3000 m, water boils at 90 °C in a sun-heated tank. A loose cap vents pressure, but also draws dust that clogs nozzle calibration screens. Twist to second detent, then quarter-turn more.

Workflow Checklist for Alpine Inspection Sprays

Base station on 2 m carbon tripod, 5 W radio, battery warmed to 20 °C.
RTK Fix rate logged for 3 min ≥ 99 %.
Spectrum sweep for EMI spikes; adjust antenna or offset track.
Nozzle calibration verified with patternator sheet; droplet D[v0.5] recorded.
Swath width set per wind, slope, droplet size.
IPX6K hatch seals inspected—no grit, no twist.
Return-home altitude 25 m above tallest obstacle plus thermal buffer.
Bladder refill filter 100 mesh to protect ceramic nozzles.

Frequently Asked Questions

Q1. Can the T50 spray during summit sleet or low-cloud drizzle?
Yes. The IPX6K rating certifies resistance to 100 L min⁻¹ water jet at 100 bar from 3 m, so light freezing drizzle is harmless. Keep battery temperature above 10 °C with insulated transport pouch; flight time drops only 90 s in 0 °C vs. 20 °C.

Q2. How does the spherical radar react to sheer rock walls?
The radar distinguishes vegetation (0.5–5 cm sway) from static rock by Doppler shift. Set sensitivity = Orchard mode; the aircraft will track foliage at 2 m yet ignore cliff faces > 30 cm diameter, preventing false braking.

Q3. What base-line length is needed for centimeter-level precision above 3000 m?
≤ 5 km baseline keeps RTK Fix rate ≥ 99 % even with 8° satellite mask angle. Place the base on the same mountain mass to avoid tropospheric bias; height difference pilot-to-base should be < 500 m for best vertical accuracy (±1.5 cm**).

Ready to quote your next high-altitude contract? Contact our team for a mission-specific flight demo or compare the compact T25 if your ridges average < 15 ha per take-off point.