X-Plane Hawker Siddeley P.1127

The Hawker P1127 and the Hawker Siddeley Kestrel FGA.1 are the experimental and development aircraft that led to the Hawker Siddeley Harrier, the first vertical and/or short take-off and landing jet fighter-bomber.

This X-Plane model is the latest release of an ongoing project.

Notes on Flying Hawker P1127/Kestrel/Harrier/AV8 aircraft:

Copy the contents of airfoils to \xplane\airfoils

You need to configure your controls for normal flying plus airbrake toggle, gear toggle, vector forward and vector aft buttons. The flaps are coupled to the vector position so a separate button is not required

1. The vectored thrust rotates from fully aft to about 99 deg, which means there is a small thrust component forward which allows the plane to be flown backward or slowed down rapidly in flight. On the ground, the airplane may sit slight nose high which means that if the vector is set to 90 there is a forward component which will cause it to taxi backward! The best way to alleviate this is before powering up the engine to set the thrust vector to about 85. In practice the full vertical take off consumes a lot of fuel, I am told 60 gals per minute. Having said that a VTO with the transition to forwarding flight should take less than 15 secs, a carrier roll about 7 secs.
2. In the hover the types of planes are affected to varying degrees by the wind direction, a full side on the 10kt wind will hit the fin and cause the plane to rotate. The outer wing will be traveling faster than the inner wing so any lift generated will cause it to rise. This means the vector is no longer fully vertical so may cause the plane to descend so at low altitudes there may not be enough time to recover.
3. The plane's Pegasus engine gives a thrust to weight ratio > 1, meaning that in horizontal flight it will accelerate rapidly. A rolling deck takes off from a carrier is less than 8 seconds, without a catapult.
4. Observe sensible limits when letting the undercart down, the vector is also tied to the flaps so the same applies, too fast and they will get ripped off.
5. To slow down, cut the power, nose up till the velocity falls below 300kts then airbrake. When velocity is below said 220 kts start applying the vector is maybe 10 deg increments, lowering the gear also slows it down. Be aware of possible pitch changes when doing this.
6. At low speeds, just above when aerodynamic controls are ineffective valve opens on the engine and bleeds gas to thrusters at wing tips and the lower front and rear for pitch and roll. There are also lateral thrusters at the rear for yaw control. These thrusters are coupled to the same control rods used by the ailerons, elevator, and rudder so normal stick control applies. It becomes difficult to get out of situations where attitude is beyond 30deg in any axis because the thrusters lose some of the vertical components.
7. It is best to land from a semi-hover with the nose slightly down during descent with the rate of descent controlled by power setting. It is best to try for slow forward landing with the vector set to about 88 deg and you probably need 85 percent power before touchdown which needs to be applied allowing for engine spool up time. As soon as it touches you want to power off and vector full to stop the rolling forward and apply wheel brakes. For a vertical landing from hovering the maximum descent rate from the official notes for a later model is 12fps, this is very hard to see and even minor throttle adjustment can affect this. The real plane actually also has a fine throttle adjuster. Pilots notes say max descent rate is 12 fps.
8. For carrier ops: hopefully, the ship is steaming into the wind at maybe 20kts+, for flying on a good day, wind speed in excess of 10kts is a bonus. This means that you have 30kts with brakes on. The same applies when landing, I am given to understand that one common practice is to fly alongside about 45 to the rear and match speed to the carrier and then come onto the deck from the side. This gives good safety margin for going around again, but at the end of a mission, fuel is likely to be short!.

The above is a commonsense precise of my own experience (on simulators), it is possible to acquire pilots notes for earlier models, although maybe less easy for later versions still in front line service.

Developer: Ray Hill.

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