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Flying the Cierva C.4

Mark Fisher

This model is freeware, © 2002, © 2004, Mark Fisher. Permission to modify and redistribute all variants is hereby granted, provided credit is given to Mark Fisher and Mat Reccaro.

X-Plane is a flight simulator, © Austin Meyer, a full featured demo of which is available at:

Juan de la Cierva designed and built a developmental series of rotary winged aircraft just after the Great War. The first of his aircraft to fly was the C.4 – after many variations were tried. 16 different forms of the C.4 were fielded. A good overview of the C.4's development, apparently drawn from the Brooks book, is available at:

The owner of the site, Chip Fyn, has offered to put up a FREE DOWNLOAD of a PDF card model, so you can build your own 3-d version, at:

Rotor (mostly) clears vstab

Fix: Limit cyclic in pitch to 1 degree.

Starter sound: I LIKE this.

• Set X-P to start w/engine off.
• Set "average time between breakdowns" to 20 hours.
• Turn off "Radio chatter" and "ATC" options - no radio!
• Load the Cierva C.4

Start up sequence:

• Confirm Battery on and pre-rotate OFF.
• Start engine. Advance throttle with <F2> key. With mouse on screen, click on ignition key, and hold button down ‘till engine catches.
• Activate "Puff smoke." Rotarys used aerosol castor oil for lubrication.
• Reduce throttle with <F1> key.
• Verify brakes are on. Press "B" to disengage, and "V" key to set brakes full. The real aircraft didn’t have brakes, but there were a lot of heavy guys around holding the tail.
• Blip "Pre-rotate" and disengage if engine RPM drops too much.
• When rotor speed gets above 20, engage "Pre-rot tension" (Mouse)
• Advance throttle gently, till ~40 rotor RPM ( Rotor pre-rotation was probably much lower than this in reality. The real Cierva spun up the rotor with gang of men pulling on a rope on the shaft, and even later models took surprisingly long takeoff rolls to bring the rotor up to speed.)
• Disengage "Pre-rotate" (Mouse)

• Full throttle, and trim mixture for best power. You’ll need EVERY horse!
• Tail down, accelerate to ~ 60 rotor RPM. As an autogyro gets most of the rotational anergy for its rotor by the force of air passing upward through the rotor disk, keeping the tail down helps magnify this effect.
• Kick rudder to keep it straight - it's a taildragger. If you don’t have rudder pedals, use the numeric keypads "1" and "3" keys for rudder control.
• Tail up gently to gain full takeoff speed: Vr ~ 50 MPH Look out for precession - bringing the tail up too quickly will induce a sharp roll to the left.
• Rotate to lift off.

• Keep speed above 45 Km/H.
• Don't get too far from base! Remember that the engine MTBO is 20 hours!, and the rotor bearings need to be hand greased (on the ground) every 30 minutes!

• For a real rotary experience, land with the mixture control (<F9> to lean, <Insert> to richen), not the throttle. Use only full rich and full lean - this simulates "blipping" the magneto on landing. Clicking on ignition might work as well.
• Without a collective, make a conventional approach. Keep your airspeed up to at least 50 MPH. Thanks to the rotor, you can exaggerate the flare and stop quickly, but it's a little hard to get the tail back up before you touch down.