# HERON energy budget (working)

Trying to close the 60-day station-keeping number.

Loads (avg, continuous):
- autonomy + nav (CEDAR): ~70 W
- ISR mast (EO/IR + radar, duty-cycled): ~120 W avg
- comms (LPI SATCOM burst): ~40 W avg
- hotel/aux: ~20 W
=> ~250 W average hotel load -> 6.0 kWh/day

Generation:
- solar array ~1.2 kW peak, PNW winter derate is brutal. assume 4.5 kWh/day avg (summer ~9)
- diesel genset 5 kW, only runs to top up battery + propulsion charge

Battery 40 kWh usable.

Net on a bad solar day: 6.0 - 4.5 = 1.5 kWh/day from diesel.
Diesel ~3.4 kWh/L electrical -> ~0.45 L/day hotel. tank 180 L.
Propulsion dominates fuel, NOT hotel. So station-keep endurance is basically
fuel-limited by drift correction + occasional repositioning.

60 days looks fine at SS<=3. Re-check SS4 hotel uplift (mast stows? radar off?).
TODO: get real solar irradiance for Mar-May off Bremerton, current number is a guess.