Flight Manual: Saab 35 Draken FSX 4.1Updated: 2014-12-22

About the simulation

Flight dynamics

Superstall

Aerobatics

Limits and restrictions

Flight dynamics

The particular flight characteristics of this simulation of Draken, or flight dynamics engine (FDE), is the result of many years of trial-and-error by me in collaboration with several former Draken pilots and mechanics.

The FDE is subject to constant improvement, and is tested on everything from low/mid-range home PCs to full-scale cockpit simulators. But since there are endless possible combinations of hardware and program settings out there, it will always be a compromise. Many people may prefer to customize the FDE (by editing the Aircraft.cfg file) to suit their own Flight Simulator setup and flying style. It's up to you.

At the moment there are a handful of commercial simulators in Sweden that are using real Draken cockpits. The FDE:s for them are different from the publically released versions, and are usually modified further by the cockpit builders. If you are planning a cockpit project (non-profit or commercial), please contact Bookmark for further information about customization, licensing, and technical support.

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Fig. 12 -  Draken cockpit simulator in development at the Ängelholm Air Museum, Sweden

Superstall

Draken can go from stationary to supersonic in less than a minute. On the downside, speed bleeds off just as fast with rising angle of attack. Always keep an eye on the AOA gauge: when approaching 15 you will lose speed and gain alpha at an alarming rate and may eventually end up in superstall.

Superstall or deep stall basically means an unrecoverable condition where all lifting surfaces on the aircraft have stalled (lost lift). It is most common on, but not restricted to, delta winged aircraft.

A delta wing does not stall gradually like a straight wing; at a certain angle of attack the whole wing area will lose lift without much warning. Hence the Stall warning system, which starts to rattle the stick before the critical AOA. When the stall warning alerts you, pitch down immediately to reduce AOA and prevent superstall.

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Fig. 13 -  Draken filmed during superstall recovery training

I have not been able to realistically simulate superstall in the current FDE, it is more a sort of tumbling spin. But close enough.

Superstall recovery

To recover from superstall, try this procedure:

  1. Extend gear.

  2. Counter the spin component by adding left yaw and right roll if you are spinning to the left, and vice versa.

  3. When reasonably stable, point the nose down to increase airspeed and reduce angle of attack.

  4. Retract gear.

  5. Raise the nose smoothly. Do not exceed AOA = 15.

Do not attempt recovery from superstall at less than 5000 m (15000 ft).

Aerobatics

Draken is an excellent aerobatics performer provided that you understand its limits. The double delta wing has good characteristics throughout the speed range but it creates an exceptional amount of drag at high angles of attack. At AOA >15 the aircraft will not accelerate even on afterburner!

Do not attempt split-S maneuvers above M 0.9 or 700 kmh, as you may not be able to achieve enough angle of attack to recover from the dive.

Limits and restrictions

Transsonic

In the transsonic speed range (~0.95–1.05 M) control response will be sluggish because of the high dynamic pressure on the large elevons, and you may be unable to pull more than 3 G at low altitude.

Never manoeuver close to the ground at transsonic speed.

Inverted flight

Flying inverted or with negative G:s is restricted to max 15 seconds to prevent fuel flow problems. The buffer fuel tanks aid in keeping the fuel flow uninterrupted, but after prolonged inverted flight you may experience flameout.

Flameout

In the engine goes out, follow the restarting procedure in Emergency procedures, which are also found on a decal inside the cockpit (in Swedish).

Optimal descent rate is achieved at M 0.9 to 550 kmh.

If you do not manage to restart the engine you may as well exit the flight. You will not be able to land Draken without engine power.

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Fig. 14 -  Engine restart instructions in cockpit

You can NOT land Draken without power.

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