AIR EXERCISE: Transitions

AIR EXERCISE:

Moving from the hover to the climb.

  • Establish normal hover;
  • Check the amount of reserve power available before committing to forward flight. You should have at least 1-inch spare.
  • From the hover, gently move into the hover taxi; slowly allow the speed of the taxi to increase by applying forward cyclic. (As a guide: when forward movement begins count 1, 2, 3 then push cyclic more forward, 1, 2, 3 cyclic more forward until forward flight is established)
  • The onset of the transitional lift is indicated by a slight cyclic stick shudder which occurs at around 12 to 20 knots.
  • As this happens apply more forward cyclic to stop the helicopter from gaining height. At this stage of the transition do not lower the collective to control height, use the cyclic to control the take-off profile. If you lower the collective, you effectively decelerating the helicopter. The aim is to accelerate.
  • The main rotor and tail rotor will experience translational lift simultaneously; therefore, right pedal application will be necessary to maintain heading whilst going through transition into forward flight.
  • Maintain the wings level.
  • Accelerate to 40kts at 10 ft AGL
  • As the helicopter reaches 40kts the nose attitude will be quite low, apply collective to climbing power. Keep the attitude exactly the same, this will result in a positive climb whilst the KIAS will continue to increase up to 65kts. This is called rotating, and the helicopter will climb away from the ground.
  • Aim to achieve 65kts (or green line -50Kts) as quickly as possible, with a corresponding increase in height.
  • Climb away at 65kts, do not remove your left hand off the collective until you leveled off.

An important point to remember is that if the wind on the day is not blowing down the runway, it will not be possible to keep the helicopter aligned with the runway while in balanced flight. The nose of the helicopter will be either left or right of the runway center line depending on the direction and strength of the crosswind.

However, I maintain a straight line until the woolometer becomes active. Then I balance the helicopter.

  • Maintain climbing power and 65kts during the climb until after levelling off.

To summarize: Look outside the cockpit at a reference point, by keeping your reference point in the same position you will automatically compensate for most control inputs required.

Approach to the hover

Once the helicopter is set up on a final approach:

  • Maintain speed of 65kts
  • Keep the landing zone at the same place on the windscreen. This will give you a constant angle of approach.
  • NB Use collective to maintain the glideslope

  • Anticipate the correct angle for the approach.
  • Maintain 65kts and control the approach angle with the collective and not by reducing or increasing speed with the cyclic. Be positive, if the helicopter is too high – lower the collective. If the helicopter is too low – raise the collective.

Whatever you do, don’t just sit there doing nothing if things are going wrong.

By speaking out aloud what you are doing will help considerably with accuracy.

  • With the aircraft set up at 65kts, aim to reach 100ft AGL. Then reduce power and slow down gradually, aiming for 50kts and 50 ft.
  • Then aim for 40kts and 10 ft AGL. The reduction in speed will automatically reduce the rate of descent. If the speed is reduced gradually, the helicopter will stop descending. Fly a gradual transition; do not attempt a quickstop!
  • Aim to enter a hover taxi 5-10m before your landing zone.
  • At the point where one slows through 40kts and 10ft, anticipate the loss of transitional lift, which occurs at between 12 to 20 knots. Be ready to increase power with the collective as this happens. Remember a further effect of raising collective is that the helicopter’s nose pitches up, which will result in a nose high attitude, as this happens apply forward cyclic to prevent excessive pitch up. Hot/high/heavy conditions will then require excessive power, which you might not have.
  • As you increase the power, apply left pedal to prevent a right yaw and to keep the helicopter following a straight line. Fly with reference to the strings while they are flying. Once the strings have stopped flying keep the nose of the helicopter lined up with a chosen reference point.
  • Gently slow the helicopter to a hover taxi, this allows one to gradually increase power and maintain heading control relative to a reference point.
  • As you are approaching the hover, the helicopter wants to adopt the hover attitude, naturally. The forward cyclic will become a ‘holding it back’, until zero forward speed is reached. Then, adopt the hover attitude.
  • Do not be embarrassed to overshoot and go around; it is safer than completing a bad approach to the hover.

With a wind from the left of the helicopter one could experience LTE or Loss of Tail Rotor effectiveness (the helicopter will yaw very quickly to the RIGHT). In simple terms, LTE is the same as Vortex Ring State. Delete – , which affects the main rotor under certain flight conditions. The occurrence of LTE is indicated to the pilot by an un-commanded right yaw, when one would expect the helicopter to weather cock into the wind and to yaw left. Do not let the yaw develop! Stop it immediately with a positive left pedal application.

The overshoot or go-around If the conditions on the final approach are such that a safe landing cannot be made, prepare for an overshoot.

Set climb power and speed 65kts; inform the tower or circuit traffic of your intentions to commence a go-around. Turn off the approach path of the runway to the dead side of the airfield, in other words move away from the active area of the circuit, to allow the other traffic the freedom to continue unaffected. Climb up to circuit height clear of the extended center line of the runway, observe the circuit traffic and re-join the circuit on the downwind leg.

COMMON MISTAKES:

Moving from the hover to the climb.

  • Failing to use sufficient collective pitch to prevent loss of height prior to attaining translational lift.
  • Adding power too rapidly at the beginning of the transition from hovering to forward flight without forward cyclic compensation, causing the helicopter to gain excessive height before acquiring airspeed.
  • An extreme nose-down attitude near the ground during the transition from hover to forward flight.
  • Failing to maintain a straight flight path over the surface (ground track).
  • Failing to maintain proper airspeed during the climb.
  • Failing to adjust the throttle to maintain proper RPM. (when the governor is off) Approach to the hover
  • Failure to maintain constant angle of decent during the approach.
  • Failure to lead the level-off sufficiently, which results in recovery below the desired altitude.
  • Failure to stop excessive pitch up, going through transition
  • Failure to adjust anti-torque pedal pressures for changes in power.

AIRMANSHIP / SAFETY:

Wind direction, power available, engine temperatures and pressures, the height velocity diagram, vortex ring.

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