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Fuselage-mounted control and thrust vectoring surfaces

IP.com Disclosure Number: IPCOM000241191D
Publication Date: 2015-Apr-02

Publishing Venue

The IP.com Prior Art Database

Abstract

This document describes a proposal for a new type of control surface, mounted on the fuselage and vertically hinged, and located behind the engines (themselves mounted on the fuselage). These surfaces would be installed on both sides of the fuselage, so as to deflect the air flow and generate a lateral force (when deflected asymmetrically), or a drag force (when deflected symmetrically). This system would hence be able to fulfil various functions: • Yaw control: o Plain yaw control (e.g. to maintain zero sideslip in a turn maneuver) o Balance engine failure o Active stabilization of yawing motion (Dutch Roll mode) • Airbrake: o Take-off (RTO) and landing o Emergency descent When unused, these control surfaces would cover the fuselage, unexposed to airflow, thus not generating more drag than the fuselage itself (except for parasitic effects). As a result, these control surfaces could replace (at least partly) the vertical tailplane and or airbrakes & thrust reversers

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Fuselage-mounted control and thrust vectoring surfaces

ABSTRACT:

This document describes a proposal for a new type of control surface, mounted on the fuselage and vertically hinged, and located behind the engines (themselves mounted on the fuselage). These surfaces would be installed on both sides of the fuselage, so as to deflect the air flow and generate a lateral force (when deflected asymmetrically), or a drag force (when deflected symmetrically).

This system would hence be able to fulfil various functions:

• Yaw control:
o Plain yaw control (e.g. to maintain zero sideslip in a turn maneuver) o Balance engine failure
o Active stabilization of yawing motion (Dutch Roll mode)

• Airbrake:
o Take-off (RTO) and landing o Emergency descent

When unused, these control surfaces would cover the fuselage, unexposed to airflow, thus not generating more drag than the fuselage itself (except for parasitic effects).

As a result, these control surfaces could replace (at least partly) the vertical tailplane and or airbrakes & thrust reversers

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1. Overall description


- The concept consists in a pair of control surfaces mounted at the rear of the aircraft fuselage on each side, behind engines, themselves installed on the fuselage (so that the space between engines and fuselage is small).

Axis of control surface hinge

Figure 1: Arrangement of the devices on a double-deck configuration. Engines (here, a pair of Bi-fans) are depicted in blue and the control surfaces in red.


- When one surface is individually deployed (on one side), it deflects the fast airflow coming out of the engines, producing a lateral force. Thanks to the aft position of the point of application of this force, the result is a yawing moment applied at the aircraft's center of gravity. This yawing moment can serve various functions:

• Controlling the aircraft's sideslip (frequent usage). For instance, when landing with cross wind, the pilot uses the rudder to create sideslip, in order to align the aircraft with the runway. Also, when performing a turn manoeuver, the pilot may use the rudder (this time to cancel the sideslip induced by the aircraft bank angle).

• Counteracting the force asymmetry of an engine failure case (exceptional usage). When the right engine fails, one would want to deflect the left control surface, in order to create a right-wise force, so as to create a moment opposing the yawing moment from the remaining engine. Figure 2 depicts this situation.

• Actively stabilizing the aircraft's natural yawing oscillations, or Dutch roll mode (frequent usage). By generating an order proportional to the yaw rate, this system

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would effectively act as a yaw damper, actively contributing to stabilize the aircraft's natural motion (as is currently the case with the rudder).


- These functions being traditionally fulfilled by the fin and rudder, an immediate benefit of the proposed system is a potential reduction of the VTP area....