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Kakapo Medium Utility Helicopter

A medium utility helicopter with a capable range, custom flight management system, and smooth handling. A focus with this design has been practicality starting with good visibility for the pilot with a clear and functional cockpit. The helicopter is capable of being operated in a hover solely by the autopilot while you head down and up using the dual-seat harness on the rear hoist.

• Twin Jet engines
  
• Rear cargo ramp
  
• Rear hoist with two harnesses
  
• Main winch with twin magnets
  
• Flight management system with touch screen/keypad entry
  
• Six passenger seats
  
• Functioning autopilot
  
• Twin turbofan rotor
  
• Retractable Landing Gear
  
• Motorized wheels for easy taxing

The vehicle holds 4500L of Jet A1 with around 90-120min endurance at 75% throttle and single or dual engine usage. Range is roughly 120km at recommended settings, and a top speed without jet exhaust assist of 32 knots. Handling is smooth. Flight management system prevents exceeding max rotor speed, which causes instability for the helicopter.

Due to the autopilot and twin seat rear hoist, it is capable of allowing complex passenger mission completion with a single person while hovering. Set the autopilot, hop in the operator winch, and control the winch with hotkeys as indicated. The winch goes up and down as normal, but can be moving in and out of the helicopter using the rail.

1. Check Master Power ON (right of pilot)
2. Lights ON (center roof panel)
3. Fuel Pump ON (select a tank, and select OUT pump for any or all tanks in roof panels)
4. Engine START (single or both, buttons in roof panels)
5. Monitors ON (center roof panel)
6. Generator ON (recharges battery using jet engine, roof panel right)
7. Throttle to 75% (required for liftoff, when not in High Torque mode).
8. Collective UP
9. Gear RETRACT above 10m

If your hear a buzzer alarm, this is a MASTER CAUTION. Check indicators, likely battery is critical or fuel pressure for engines lost.

1. Attach JET A1 Nozzle to vehicle (left side)
2. Intake Fuel Pump IN set ON (left of copilot seat)
3. Fuel Center Tank will fill
4. Set Center Tank OUT to ON
5. Set Left and Right Tank IN to ON
6. When full, press RELEASE (left of copilot seat)
7. Set Left and Right IN to OFF
8. Set Center tank IN to OFF
9. Set Intake Fuel Pump IN to OFF

Fuel will be drawn from any tank with a pump OUT set to ON. Recommend taking from center tank for normal operations. Note the intake pumps are connected directly to the center tank.

1. Attach JET A1 Nozzle to vehicle (left side)
2. Intake Fuel Pump OUT to ON (left of copilot seat)
3. Center Fuel Tank IN and OUT to ON
4. Left and Right Fuel Tank OUT to ON
5. When empty, press RELEASE (left of copilot seat)
6. Set all pumps to off

This is found on the AP button. Note the buttons can be hard to press. On this screen are four options, with two buttons beside each. Pressing a PLUS next to an item will transfer entry from the keypad into this setting. Pressing the box at the start of each item will turn this setting ON or OFF. Note that the master autopilot button must also be engaged for autopilot to function.

• Heading. This will hold the helicopter at the provided heading. Note that the copilot screen has a navigation settings mode that can populate this value using X and Y coordinates (and will be updated).
  
• Altitude. The helicopter will hold this altitude. Be careful with descending values especially in bad winds as the flight management system may dip below your chosen altitude.
  
• Radar Altitude. This performs as above but using a distance sensor mounted below the aircraft. Note that water does not activate this! So do not use this over water!
  
• Horizontal speed. This will hold the helicopter at the provided horizontal speed.

Do NOT exceed 35 knots with the horizontal speed setting or the helicopter will not be able to maintain altitude. Negative values are not recommended when used with altitude holding, as the flight management system isn't able to adequately cope with the change in collective operation.

From the copilot station, using the NV screen, X and Y coordinates can be entered. Once these have been entered (put setting into keypad, then press the PLUS next to required setting), you can then enable the setting by clicking the box beside it. This will populate the autopilot values, and update realtime. The system is hardcoded not to exceed 30knots if the speed management is used. It will slow down as it gets closer to the target.

Currently this can only be activated while rotor RPS is below 5. This will disable all gearing, drastically reducing fuel economy. Note the flight management system is not tuned for this setting, and rotor could exceed max speed during flight operation with heavy loads. Generally it's not needed, the eight blades on the helicopter and twin engines provide more than enough power for most heavy loads.

The flight management system handles engines being switched OFF during flight fine, without degradation of operation so long as minimum throttle is maintained (75%). However, ensure you have at least 100m altitude before switching an engine ON, as the rotor power will not be rebalanced immediately and you will lose substantial altitude in the process.

Buzzing Alarm
Master Caution Alarm. Check fuel pressure, check battery state. If fuel pressure low, ensure a tank with fuel is set to OUT. If battery low, check generator turned on. If throttle is below 50% there may not be enough power to maintain charge in the batteries for sustained periods of time. Increase throttle to recharge.

Autopilot not achieving heading
Winds too high. Manually adjust headings to compensate. Working on solving this in future, but for now the helicopter has been tuned for fair weather for autopilot.

Gauges and lights diming
Check power, likely very low. Ensure generator ON (roof panel right).

Helicopter rolls when landed
Gear likely not down. Check gear down before landing.

No power
Check Master Power breaker (right of pilot seat) is turned ON. Check battery level. Check Generator turned ON. If power cannot be restored, connect external power source to electrical connector on right side beside crew door.

Rear hoist won't move in/out
Check rear cargo door open. Lateral movement of rear hoist is mechanically disabled when the rear cargo door is closed.

I did a tremendous amount of research about how others approached systems. I'll do a proper write up of inspiration sources shortly. It's a little hard because I ended up writing everything myself, as tuning others work became too complicated in such a small craft.