CarterCopter Technology Demonstrator

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CarterCopter Next CC

NxCC
for X-Plane 6.51
© Mark Fisher, 2003 ~ mf70@hotmail.com

Note: A Pilot’s Operating Handbook (POH) is a primer on the operation of a specific aircraft. This POH is intended as a primer on the operation of the X-Plane model of the CarterCopter Next CC (NxCC). It is designed to run under the flight simulator X-Plane, with a full-featured free demo available from www.x-plane.com. This X-Plane model is freeware; it may be freely modified, copied, and redistributed, provided a) it is not part of any for-profit package other than X-Plane itself, and b) credit for this design is given to Mark Fisher and Austin Meyer.
Thanks to the test pilots: Otha Vaughn, Kevin Smith, Joe Churchman, and Doug Marker. And you! If you have any questions or suggestions about this model please contact me at the above e-mail address.
This model: For a number of reasons, this model is not an exact replica of the real NxCC. "Flying" techniques discussed here should not be taken as a full and direct description of skills needed in the real NxCC.

Overview:

The CarterCopter is a hybrid aircraft. It operates in three modes:

Between 0 and 60 knots, it functions as a helicopter, taking power from inertia of the rotor. Since power is not fed into the rotor from the aircraft, it does not have the anti-torque problems of conventional helicopters. It only operates in this mode for a short time, however! What is really dangerous is low airspeed and low rotor rpm (as in any gyro).
Between 70 and 125 knots, it functions as an autogiro. The wings only supply a small fraction of lift.
Between 125 and 220 knots, it functions as a fixed wing aircraft. The rotor is still there, but is only taking enough energy out of the airstream to avoid folding up – around 100 rpm.

At all times, "steer small." Work to find the smallest input that will have the desired effect. Over-control only masks the response of the aircraft.

As a general rule DON'T let forward speed drop below about 70 knots (certainly keep above 50-60) unless you are coming in for a zero roll landing or at high altitude and experimenting.

Unique Controls:

There is an unfamiliar control on the throttle quadrant – the "Rotor Trim" lever. This does not directly control the rotor. Instead it controls the link between the elevator trim and the rotor pitch cyclic. In the "up" position, the rotor mirrors the pitch trim, allowing pitch trim before the elevator is effective. In the "down" position, the rotor pitch cyclic is not affected by elevator trim.

There is also a "collective" control. This controls the pitch of the rotor blades. This is used as a lift control in helicopter mode, and as a rotor rpm control in autogiro and fixed wing modes.

A final addition in the NxCC is the customized Electronic Flight Instrumentation System (EFIS). This generates several cheery warnings. FLAPPING WARNING and FLAPPING CRITICAL warn of excessive rotor lift – reduce rotor pitch.

X-Plane key commands:

Almost all control functions are available from within the cockpit by clicking on the appropriate part of the screen. You may use "Special | Show mouse control areas" to highlight the "hot" areas of the screen. Some general controls - viewpoint especially, are accessed either from the menu structure or from the keyboard. Some vital views: "W" = forward view, "Q" = look left, "E" = look right, "A" = following view, <Shift-"\"> = outside view. Other useful keys: "G" = landing gear toggle, "B" = brake toggle. Other needed keys will be indicated as they are needed in carets - "<>".

Running Take-Offs

Principles:

The NxCC will be acting as an autogiro. At takeoff, the NxCC has two sources of energy: the thrust of the engine-prop unit, and lift from the inertia-rotor unit.

The first step is to store sufficient takeoff energy in the rotor system. This is done via the "Pre-Rotate" buttons.

Procedure:

Set up X-Plane: Go to "Settings, Hardware and Flight Mode" and set Joystick Sensitivity to 75%-50%. This introduces a dead zone in the joystick response that corresponds to the stick damping in the real thing.
Set up instruments:

Set altimeter. <Enter, select ATIS report>	Engage fourth button down (ROT) on EFIS.<Mouse>
Set radios.<Mouse>	Collective at 0° (White area) <F5 - F6>.
Set autopilot to planned cruise altitude.<Mouse>	Pitch trim at bottom – nose up trim. < [ - ] >
Set VVI to desired vertical speed (500).	Throttle at idle <F1>.
Rotor trim at top.<Mouse>	Flaps to first notch (5°) (Not installed on real NxCC)

Start engine – engage RED pre-rotate switch, and WHITE pre-rotate – make sure brakes are locked. <Mouse only>
Advance throttle to 50% <F2> and you should hear rotor spin up. Rotor speed is available on the ROT screen of the EFIS and on the dedicated digital tach under the pre-rotate switches.
When at 350 rotor rpm, release the WHITE pre-rotate switch and CC will automatically increase pitch on prop. Release brakes and you will accelerate down the runway. Move stick gently forward and add 2° collective.
Steer with rudder pedals (or whatever rudder control you have) to aim down runway centerline.
At approx. 60-70 knots ease back on stick. If you want extra lift, pull collective <F5> slowly at same time to about 4°. In a good lift-off your nose should come up smoothly and the instrument panel top should not go much above the horizon.

Jump Take-Offs (zero roll take-off)

Principles:

The NxCC will be acting as a helicopter for the first 100 vertical feet of flight, and then transition to autogiro mode at 100 Ft. AGL, where it will accelerate to slow flight speed of 70 knots.

The period of time between takeoff and the establishment of flight speed is quite short. The entire period should be treated as a takeoff – if there is any delay in establishing flight, the aircraft should be landed again immediately.

Procedure:

Start engine – Trim full nose up (bottom position) <]> – collective at 0° <F6>.
Engage pre-rotate tension and pre-rotator – apply throttle 25" MP <F2>. In reality, the spin up takes three minutes.
At 425 rotor rpm, advance throttle to full, release pre-rotator.
Commence steady but swift (not fast) pull on collective <F5> up to 12°.
Just after commencing the collective pull, move stick to maintain level attitude. Unlike a helicopter, you won’t have to pitch forward to gain flight speed, as there’s a Corvette engine pushing. It is possible to make "bunny hops" by closing the throttle before pulling the collective – this will help you get the feel of things.
Keep the top of the instrument panel on the horizon – climb to approx. 1500 ft. Trim aft and reduce flaps as speed is gained.
Slowly reduce collective to about 4° (you can start this from about 100-200 ft, or when getting "flapping" or high collective" warnings).

Climb Out to Low Speed Cruise

Principles:

The NxCC will be operating as a conventional autogiro. The rotor will be tipped back around 5°, and will be supporting over half the weight. Rotor rpm will be around 220 rpm. (More rpm = greater drag and less forward speed and greater engine power is needed – the goal here is to minimize fuel consumption and avoid using excessive engine power.) Too little collective and the rotor rpm will go over 300 and this needs more power from the engine to keep up airspeed.

Don't let speed drop below about 70 knots (certainly keep above 50-60 as it can be difficult to regain speed ESPECIALLY if flying at a low altitude).

You may see a FLAPPING WARNING. If so, "steer small," and reduce collective pitch gently.

Procedure:

Retract gear <G> to reduce drag and gain forward speed.
Climb out to about 1500 feet.
Once at cruise altitude, ease back to about 2/3 – 1/2 throttle <F1>. Bring rotor trim to "min." <Mouse> Adjust elevator trim <[ - ]> for 130 knots speed.
Adjust collective <F5 - F6> so that you have between 220-250 rotor rpm

High Speed Cruise

Principles:

The NxCC will be operating primarily as a fixed wing aircraft. As the aircraft is trimmed forward to balance increasing wing lift, the rotor will be almost completely aligned with the line of flight. Because it is not absorbing energy, 1) it will slow down to under 140 RPM, and 2) the reduced drag will allow the NxCC to continue to accelerate. This is that "High m " flight!

Procedure:

In level flight, bring engine power to 80% - 100%.
As speed builds, use forward elevator trim. "Steer small" – avoid jerky control inputs.
Reduce collective to 0°. Bring "Rotor Trim" toward "min," monitoring rotor speed. When speed starts to drop, you've got the correct setting.
If rotor speed drops below 80, adjust with collective and rotor trim.
In X-Plane, you may see the lift vectors of each lifting surface – go to outside view < | > and press <Ctrl – "/"> twice. The goal is to have little or no lift from the rotor.

Descent from High Speed Cruise

The NxCC will be operating primarily as a fixed wing aircraft. As power is reduced and aircraft is trimmed forward to maintain speed, the rotor will be almost completely aligned with the line of flight. High m flight will continue.

Transition to Autogiro Mode

As power is reduced and trim is brought back to maintain altitude, the rotor disk will capture more airflow and gain energy, increasing its rpm. Restore "Rotor Trim" to "Max." To build rpm more rapidly, reduce the collective to –2° until rotor speed is around 300 rpm, then increase collective to maintain that speed.

Run-On Landings

With rotor stabilized at 300 rpm, adjust engine power for desired rate of descent. Maintain airspeed of at least 100 knots. Fly a normal approach, but use collective to flare. Pulling back on the stick will tip rotor back, slowing the aircraft, but reducing braking effectiveness.

Vertical Landings (zero roll landing)

Principles:

The NxCC is now going to enter helicopter mode, using the stored energy of the rotor to control descent. Caution: at 300 rotor rpm, there is only enough energy for one descent – you can’t hover! A vertical descent is possible from altitude, but a forward approach gives better visibility and control.

Procedure:

Lower gear!
Come in at about 500-750 ft AGL over the end of the runway.
You need to be at 70-80 knots or less and with min collective. The trick is to lower engine power (but keep hand on the throttle) and do what ever it takes to spin the rotor up as fast as possible.
As you head down the runway at about 400ft AGL pull back on the stick and go nose up – watch your airspeed closely, use light power and light forward stick if the sink rate becomes too fast or if airspeed slows too much. Is the gear down?
Be ready to pull steady collective if you need to slow descent but remember that this slows the rotor and you need as much rotor speed as you can get and keep. Is the gear down?
At about 100 ft allow CC to settle – apply light collective to ensure a slow last few feet down. You can hit the deck at up to 20 ft/sec. What ever you do, avoid flying backward just prior to reaching the runway.