The purpose of multiple engines is to provide safety in the event of failure of one engine. Pilot procedures are specific in the event of an engine failure and require immediate and proper action. Sometimes an emergency is compounded by improper sensing and incorrect action.

All PWCR^TM airplanes are multi-engine airplanes, that is, they have both thrusting and blowing engines. The Model P airplane can still fly in the event of failure of either engine. If the blowing engine fails, the Model P airplane becomes a conventional airplane and can fly to any field long enough for a regular landing.

In the event of thrusting engine failure, the Model P PWCR^TM is controllable with extended glide and low landing speed. The blowing air over the flap lowers wing drag, increases effective aspect ratio, and provides momentum thrust.

The result is that the PWCR^TM will glide at a shallow angle. The effective L/D ratio is increased to the point where a glide ratio over 20 to 1 is possible. This means that from an altitude of 5000 feet, a PWCR could fly over 20 miles. The short field performance of the airplane is still available and an airport, particularly a small one, is within gliding range.

The following graph from the WSU Feasibility Report, showing rate of climb and descent at different power and altitude settings, corroborates this performance.

In the event of main engine failure during the take-off run, the speed will be low. Closing the throttle of the blowing engine(s) will increase the weight on the landing gear and increase braking effectiveness. The take-off run is short and sufficient runway of a rated field will be available at any time during the ground run to come to a safe stop.

In the event of main engine failure during climb-out, the blowing engine(s) would be set at maximum power and the PWCR^TM would be able to glide at a relatively flat angle. Since full blowing effectiveness exists, the landing speed will be slow and short fields would enable a safe landing. No unusual procedures are required. The rate of sink would be about 400 ft/min, giving over a full minute from an altitude of 400 feet. This is sufficient time to prepare for a landing since the PWCR^TM could fly over a mile from that altitude. In summary, PWCR^TM airplanes have unique safety features resulting from circulation control.

The Model J PWCR^TM has a higher safety margin. With failure of a single engine, either thrusting or blowing, the airplane is controllable and retains adequate thrust or blowing to fly safely.