# US 10,118,695 B2 · Directional control system and method of providing directional control > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,118,695 B2 - Document ID: US10118695B2 - Status: Granted - Kind: B2 - Application number: 15/074,454 - Filed: 2016-03-18 - Published: 2017-09-21 - Granted: 2018-11-06 - Earliest claimed: 2016-03-18 - Assignees: Pratt & Whitney Canada Corp. - Applicants: Pratt & Whitney Canada Corp. - Inventors: Jean Thomassin; Serge Dussault; Andre Julien; Gordon Saby; Richard Ullyott - Web page: https://patentgrep.com/patent/US10118695B2 ## CPC - B64C 27/82: characterised by the provision of an auxiliary rotor or fluid-jet device for counter-balancing lifting rotor torque or changing direction of rotorcraft - B64C 21/04: for blowing - B64C 27/12: Rotor drives - B64D 33/02: of combustion air intakes - B64D 33/04: of exhaust outlets or jet pipes - B64D 33/10: Radiator arrangement - B64C 2027/8245: {using air jets} - B64D 2033/024: {comprising cooling means} - Y02T 50/10: Drag reduction - B64C: AEROPLANES; HELICOPTERS - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A directional control system for a rotorcraft having a tail boom including a no-tail-rotor apparatus configured to control rotorcraft yaw using forced air ejected from the tail boom and a duct configured to deliver the forced air to the no-tail-rotor apparatus. The directional control system comprises a heat exchanger having air passages and fluid passages, the air passages in fluid communication with the duct, the fluid passages in heat exchange relationship with the air passages and configured for receiving a cooling fluid, and a forced air driver in fluid communication with the duct for driving the forced air through the duct to the no-tail-rotor apparatus. Methods of providing directional control in a rotorcraft are also discussed. ## Claims ### Claim 1 A directional control system for a rotorcraft having an internal combustion engine, a main rotor and a tail boom, the directional control system comprising: a no-tail-rotor apparatus configured to control rotorcraft yaw using forced air ejected from the tail boom; a duct configured to deliver the forced air to the no-tail-rotor apparatus; a heat exchanger in heat exchange relationship with an internal combustion engine, the heat exchanger having air passages and fluid passages, the air passages in fluid communication with the duct, the fluid passages in heat exchange relationship with the air passages and configured for receiving a cooling fluid of the internal combustion engine; and a forced air driver in fluid communication with the duct and the air passages of the heat exchanger for driving the forced air, including engine cooler exhaust air from the air passages, through the duct to the no-tail-rotor apparatus. ### Claim 2 (depends on 1) The system of claim 1, wherein the no-tail-rotor apparatus includes: at least one nozzle in fluid communication with the duct, having a linear configuration and extending longitudinally along an outer surface of the tail boom; and a thruster on the tail boom and in fluid communication with the duct, the thruster positionable to be directed laterally with respect to the tail boom in a selected one of a plurality of different orientations. ### Claim 3 (depends on 1) The system as defined in claim 1, further comprising an exhaust conduit communicating with the duct downstream of the heat exchanger and upstream of the no-tail-rotor apparatus, and a valve modulating the communication between the exhaust conduit and the duct. ### Claim 4 (depends on 2) The system as defined in claim 2, wherein a distal end of the tail boom includes an end portion with a slot defined therein, and an inner element having a shape complementary to that of the end portion is received within the end portion, the inner element being pivotable within the end portion and having a hole defined therethrough cooperating with the slot of the end portion to define the thruster. ### Claim 5 (depends on 1) The system as defined in claim 1, wherein the heat exchanger is received within the duct. ### Claim 6 (depends on 1) The system as defined in claim 1, further comprising a bypass passage having one end communicating with the duct upstream of the heat exchanger and an opposed end communicating with the duct downstream of the heat exchanger. ### Claim 7 (depends on 1) The system as defined in claim 1, wherein the fluid passages of the heat exchanger are configured to receive a liquid coolant. ### Claim 8 (depends on 1) An assembly comprising an engine core, the internal combustion engine forming part of the engine core and including at least one rotary internal combustion engine and the system as defined in claim 1, each rotary internal combustion engine having a housing including cooling passages in fluid communication with the fluid passages of the heat exchanger. ### Claim 9 (depends on 8) The assembly as defined in claim 8, wherein the forced air driver is a fan in driving engagement with the at least one rotary internal combustion engine. ### Claim 10 A method of providing directional control in a rotorcraft having a main rotor and a tail boom, the method comprising: cooling a component of the rotorcraft with a liquid coolant; cooling the liquid coolant from the component in a heat exchanger by circulating a cooling airflow through the heat exchanger in heat exchange relationship with the liquid coolant; and circulating the cooling airflow from the heat exchanger through the tail boom and out of the tail boom, including creating a boundary layer flow along an outer surface of the tail boom with the cooling airflow, and directing a downwash from the main rotor around the tail boom with the boundary layer flow to produce a thrust opposite a torque from the main rotor. ### Claim 11 (depends on 10) The method as defined in claim 10, wherein cooling the component of the rotorcraft with the liquid coolant includes circulating the liquid coolant through a housing of an internal combustion engine of an engine assembly of the rotorcraft. ### Claim 12 (depends on 11) The method as defined in claim 11, wherein circulating the cooling airflow is performed by driving rotation of a fan with the engine assembly. ### Claim 13 (depends on 10) The method as defined in claim 10, wherein circulating the cooling airflow out of the tail boom includes circulating the cooling airflow through two elongated slots extending along a length of the tail boom. ### Claim 14 (depends on 10) The method as defined in claim 10, wherein the boundary layer is created from a first part of the cooling airflow, the method further comprising expelling a second part of the cooling airflow out of the tail boom through a thruster, including orientating the thruster to create a yaw moment on the rotorcraft. ### Claim 15 (depends on 14) The method as defined in claim 14, further comprising modulating a flow of the cooling air out of the thruster. ### Claim 16 A method of providing directional control in a rotorcraft having a main rotor and a tail boom, the method comprising: creating a flow of air from an environment of the rotorcraft into the tail boom, at least part of the air circulating in heat exchange relationship with a cooling fluid of the rotorcraft before reaching the tail boom, the air picking up heat from the cooling fluid; and circulating air out of the tail boom through a thruster positionable to discharge the air along a selected one of opposed sides of the tail boom, including orienting the thruster to create a predetermined yaw moment on the rotorcraft with the air discharged therefrom. ### Claim 17 (depends on 16) The method as defined in claim 16, further comprising circulating the cooling fluid through a housing of an internal combustion engine of an engine assembly of the rotorcraft. ### Claim 18 (depends on 17) The method as defined in claim 17, wherein creating the flow is performed by driving rotation of a fan with the engine assembly. ### Claim 19 (depends on 16) The method as defined in claim 16, wherein circulating the cooling airflow out of the tail boom includes circulating the cooling airflow through at least one nozzle extending longitudinally along the tail boom to direct a downwash from the main rotor around the tail boom to create a thrust opposite a torque effect of the main rotor. ### Claim 20 (depends on 16) The method as defined in claim 16, further comprising modulating a flow of the air out of the thruster.