UK Heli Log

One of the harder moves and certainly one of the first big milestones for most pilots is the Pirouette Flip or Piro Flip. This is where the heli flips (rolls) while the helicopter is pirouetting (yawing) at the same time. To the untrained eye it almost looks like the heli is completely out of control…but it’s not!. What’s frightening about the move is when something goes wrong and you have to bail out the heli can be in almost any position.

So where do you start

First of all this is a more advanced move so there are a few prerequisites required. Whilst you can attempt to start piro flips before knowing all of these inside out, it might save you some cash if you do know them:

• Forward flight
• Backwards flight
• Forward inverted flight
• Backwards inverted flight
• Basic control while pirouetting
• Basic control while pirouetting inverted

Of course it goes without saying that a simulator is a requirement, to learn without one is masochistic in my opinion.

Stick Movements (assume mode 2 TX)

Cyclic Stick

In a nutshell what you are doing is keeping the cyclic (right stick) in phase with the pirouette (yaw) position of the heli. This can be demonstrated with the heli spooled up and on the ground (try this on your sim):

• If the heli is nose in (0°) and you pull the cyclic stick back the rotor disk will pitch forward.
• If the heli is nose right (270°) and you move the cyclic stick left the rotor disk will pitch forward.
• If the heli is nose out (180°) and you push the cyclic stick forward the rotor disk will pitch forward.
• If the heli is nose left (90°) and you move the cyclic stick right the rotor disk will pitch forward.

So what this demonstrates is the main rotor disk can be kept pitched forward no matter what position the tail is in. And we know that if the main disk stays pitched in the forward position then the heli will flip forward.

This example was 4 positions in a 360° pirouette but obviously if you are doing a sustained continuous pirouette then the stick position needs to be adjusted through-out the whole 360 rotation. In practice that equates to a circular stirring motion which should be analogous to the above example (imagine doing the above example but having do it quickly).

Collective Stick

The key to the collective stick (left stick) is about maintaining a constant pirouette speed. A constant pirouette speed will make it easier for you to keep the stirring action on the cyclic stick in phase (in time) with pirouette position.

The throttle stick basically stays around the mid point and is delicately moved up and down in relation to whether the heli is right side up or inverted (still maintaining a constant rudder position).

Key Off Point and Pirouette Direction

The key off point is the point at which you decide to initiate your piro flip, which dictates the direction of flip (which way the disk flips) and is also used for phasing orientation. For example if you start a piro flip nose in then by the time you have flipped to inverted horizontal again you should be at your key off point. If that’s not the case then your stir speed on the cyclic is not matched to the pirouette speed.

The best place to key off in my opinion when learning is nose in because when you start to flip back the tail is at a high attitude and easy to track by eye.

The best direction to pirouette when learning a piro flip is anti-clockwise as that’s the natural direction a heli wants to spin due to torque (assuming a clockwise main blade rotation). This is likely to give you slightly better gyro performance (although debatable in some modern gyros) and more engine power in reserve.

How Many Pirouettes per Flip?

It’s really up to you, 2 pirouettes per flip is a good place to start when learning as 1 pirouette per flip is quite demanding on the cyclic. More than 2 and you’ll have to really speed up the pirouette rate in order to stop the heli loosing altitude which makes matters more difficult for someone learning.

TIP: If you need to flip faster increase the size of your cyclic stirs, conversely if you need to flip slower decrease the size of your stirs.

Breaking it down

• Practice half piro flips from upright to inverted and back. Put a pause in the middle of the half flips so you can correct yourself and get level.
• Concentrate on keeping the pirouette speed moderate and constant to begin with.
• Make sure you have a key off point where you start the flip and always use it to being with.
• Track the tail with your eye all the time (keep your eye on the ball) to keep it in phase
• As you get better remove the pause from in between upright and inverted and add a little more speed. Once you’ve got it sorted do some more practice