DRAGONS OF THE DEAD MANS ZONE!

1. DRAGONS OF THE DEAD MANS ZONE! By Len Klopper with acknowledgment to Greg Gremminger

2. “Behind the power curve” • Definition Lacking the engine thrust to extricate the aircraft from a perilous condition Applies to all aircraft but the risk of stalling prevents most fixed-wings from going there – Gyro’s and Helicopters are especially vulnerable

3. Analogy • As its speed gathers and the wings develop lift, the aircraft enters the normal operating regime or 'envelope' of the power curve. It's just as you must carefully manage your momentum when driving your car in snowy, icy conditions. When you lose enough momentum, all the power in the world cannot rehabilitate an out-of-control skid • FACT! All the power in the world will not let you recover from behind the power curve flying if you do not have adequate altitude to let the airspeed increase!

4. Gyro’s are especially vulnerable • They cannot stall • They cannot spin • Fear of stalling and spinning is lost in Gyro training • Low airspeed Gyro’s WILL lose a lot of altitude before restoring sufficient rotor speed/energy to prevent an unplanned impact with terra firma • In a fixed wing, when you put the nose down, as you gain airspeed the wing  immediately starts producing more lift • In the case of a gyro, it first has to convert the airspeed to rotor speed and there is a lag as the rotor catches up in order to generate lift • This is more evident if the gyro has particularly heavy rotors, which results in a greater lag than lighter rotors. • Often results in hitting the ground – Controlled Flight Into Terrain (CFIT)

5. Often, Fire follows Behind the Power Curve IncidentsWhy? • Fact: It is apparent that hitting the ground whilst desperately trying to recover from a behind the power curve event often results in a fire.  • This is usually be because you tend to land (impact) nose-high (tail first) at full power with a screaming motor at full turbo with a very hot turbocharger and exhaust pipe right behind the fuel tank. • The impact ruptures the fuel tank spilling fuel over ignition sources

6. Auto Ignition Point • Gasoline (Petrol): 246–280 °C • Exhaust Gas: 800-900 °C • Even if the exhaust itself is 200 °C cooler it is still well above the auto ignition point!

7. How do we end up “behind the power curve” • Too low, too slow at full power • Engine failure without adequate altitude • Power loss during vertical descent • Too steep climb after take-off (show off) • Failure to get adequate airspeed after takeoff (too heavy/density altitude) • Low-level Distractions (hunting, photography) allowing airspeed to inadvertently decay You’re in the “Dead Mans Zone”!

8. The HV curve is an actual graph that depicts the minimum combination of height potential energy and speed potential energy required to make a safe landing IF power is not available – if the engine STOPS!

9. Too low, too slow

10. Hover descent

11. Show off takeoff

12. Know your own HV curve! • Density Altitude, Fuel load and Passenger Weight all influence your HV Curve on the day and it varies! • Go to a safe altitude and descend at zero airspeed, then see how much altitude it takes you to recover rotor RPM and airspeed for a good simulated landing flare at altitude (Top tip of your HV curve) • Make a normal deadstick landing, note your height above the ground and airspeed just after rounding out to start your flare on a normal deadstick landing. (Right tip of your HV curve) • Add 50ft and 5mph for safety.

13. Remain outside your Dead Mans Zone! • Flying outside the grey area of your dead mans zone will ensure that you never fall foul of the dreaded Dragon of the Dead Mans Curve! SAFE FLYING!