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I just took my private checkride on Tuesday, and the examiner was really interesting, and absolutely committed to educating pilots. He spoke most of the time we flew, and I have listed a few things he passed on that I had not thought of before.
If you are reading this and have additions (I'm sure there are tons) and/or corrections to make, they are welcome.
1. The quickest way to get out of bad weather is with a right crosswind. (assumes bad = low pressure, N hemisphere)
2. The triangle inside the square that surrounds the H of a helipad points to magnetic north.
3. Hover power = takeoff power = cruise power. The reason for this is that most piston engines will not quit if you run them at a constant power setting. The change in power setting is the thing that allows them to hiccup and die.
4. Learn to trim the cyclic at all times, so that if you inadvertantly leave the stick you will not die suddenly.
5. You don't need to keep full ETL to do a running landing. You can come in pretty slow with limited power. (my checkride running landing was done way too fast, but within standards)
6. When you are clear obstacle on a max performance t/o it is better to ease the cyclic forward, eventually reaching the position for straight and level. If you (as I did) clear the obstacle and then push forward to get 55 kts before easing back to climb, you have too many inputs. Fewer inputs are better.
7. To find the wind direction in flight, the easiest way (without smoke stacks etc) is to look at your crab, but you still don't know if it is a quartering tailwind or headwind. Turn 90 degrees into the side the wind is coming from. Then see where you are crabbing. You will be able to tell wind direction to within about 20/30 degrees at any time with one 90 degree turn.
8. If you have a weight shift in flight, say that puts your CG forward of limits, just turn the ship sideways, and you will have enough stick to flare. (has anyone ever used this?)
Joel
>OLD WIVES TALES ALERT!!!
>"3. Hover power = takeoff power = cruise power. The reason for this is
>that most piston engines will not quit if you run them at a constant
>power setting. The change in power setting is the thing that allows
>them to hiccup and die."
>There is NO data to support that theory.
Karl,
You picked right up on my only beef with the posting. I have to disagree with maintaining the same cruise power as it took to hover, if nothing else, simply because it is a total waste of fuel. And besides that, it's hard on the engine. There is no need to cruise (unless you're in a huge hurry) with the same amount of power that it took to hover.
Plus, I'd like to add one more tip.
When you are about to make a departure from a hover, look at the grass blowing in front of you. (You have to be departing from the grass to do this.) You will notice a distinct line where the grass is no longer being blown by the rotorwash. If you set the correct departure pitch, the point where the wash quits blowing the grass will be the point at which you reach ETL. I've used this to gauge departure out of confined areas many times, and it works like a charm.
Stephen Austin
Austin Ag Aviation
Comm. Rotorcraft/Helicopter, CFI and CFII Helicopter
Comm. SEL and MEL
Instrument Airplane and Helicopter
Any time lift increases (ETL), the nose will tend to pitch up as in any powered aircraft. Without a change in pitch attitude (forward cyclic), the nose will continue to pitch upward. Any associated climb will be only temporary as you will begin to lose ETL again. Transverse flow will cause a counterclockwise rotor system to tend to roll to the right at low speeds. At higher speeds, dissymmetry of lift will be the most dominant force and will cause the helicopter to tend to roll to the left, hence the need for right cyclic at higher speeds.
The right roll (with no corrective left cyclic input) is also due to the transverse flow effect.
Just a quick synopsis; as the air moves across the disk it is deflected downward because of induced flow. The greater the distance air has to flow over the disk, the longer the disk works on it and the greater the deflection. This causes a greater induced flow velocity over the rear half of the disk and hence a decreased angle of attack on the rear portion of the disk.
This decrease in lift produced by the blade over the tail (due to increased induced flow) manifests itself 90 degrees later with a maximum down flapping blade displacement over the right side of the helicopter.
Without cyclic displacement to the left the helicopter would roll to the right. And as the helicopter continues it's transition in forward flight eventually the cyclic will have to be placed back to the right.
But Transverse Flow (10-20 knots) and Effective Translational Lift (16-24 knots) happen so close together that it would appear that you are getting nose pitch up and right roll all at once.
Transverse Flow is the increase in lift on the forward portional of the rotor disc caused by the inflow of air being more horizontal than on the aft portion of the disc.
Dissymmetry of Lift is the difference in lift between the advancing and retreating blades. Compensated for by both flapping and mechanical feathering.
Gyroscopic Precession is any aerodynamic or pilot input takes effect 90 degrees later in the direction of rotation.
Translational Lift is the rotor disc in transition from hovering flight (dirty, disturbed air) to flying in clean air effectively.
As the helicopter moves forward the advancing blade starts to fly first, which manifests itself 90 degrees later (in direction of rotation) which would be the front of the aircraft. The pilot does a modified upsided down question mark motion with the cyclic to adjust for first; Dissymmetry of Lift and second; effective translational lift.
Helicopters do in fact 'pitch up'. If you've ridden in a helicopter that did not appear to pitch up, the helicopter pilot was doing his job.