An aircraft comprising at least one propulsion unit configured to propel the aircraft in a first direction and at least one further propulsion unit configured to propel the aircraft in a second direction substantially opposite to the first direction. The aircraft also includes at least one wing, wherein the at least one propulsion unit is mounted in front of the leading edge of the at least one wing, such that the air downstream of the at least one propulsion unit flows around the at least one wing to provide lift and a longitudinal thrust in the first direction. The at least one further propulsion unit is configured to provide a longitudinal thrust in the second direction.
1. A fixed-wing aircraft comprising:
at least one propulsion unit configured to propel the aircraft in a first direction;
at least one further propulsion unit configured to propel the aircraft in a second direction substantially opposite to the first direction; and
at least one wing,
wherein the at least one propulsion unit is mounted in a fixed position in front of a leading edge of the at least one wing, such that air downstream of the at least one propulsion unit flows around the at least one wing to provide lift and a longitudinal thrust in the first direction, and the at least one further propulsion unit is mounted in a fixed position to provide a longitudinal thrust in the second direction that opposes the longitudinal thrust in the first direction, wherein the lift provided by the at least one propulsion unit causes the aircraft to take off.
2. The aircraft according to claim 1 , in which a chord of the at least one wing at a first point along a length of the at least one wing is substantially parallel to a chord of the at least one wing at all other points along the length of the at least one wing.
3. The aircraft according to claim 1 , in which the at least one further propulsion unit is mounted to a lateral outer end of the at least one wing.
4. The aircraft according to claim 1 , in which the aircraft further comprises at least one further wing, wherein the at least one further wing is a fixed wing, the at least one further wing being mounted in the first direction relative to the at least one further propulsion unit, such that the air downstream of the at least one further propulsion unit flows around the at least one further wing to generate lift, when the at least one further propulsion unit is providing a longitudinal thrust in the second direction.
5. The aircraft according to claim 4 , in which the at least one further wing includes an adjustable deflection surface at a furthermost part of the at least one further wing in the first direction and an adjustable deflection surface at the furthermost part of the at least one further wing in the second direction, which are configured to be selectively lowered in order to configure the at least one further wing to produce lift from a prevailing airflow flowing around the at least one further wing.
6. The aircraft according to claim 1 , in which the aircraft is configured such that the at least one further propulsion unit is spaced from the leading edge of any wings, to prevent the air downstream of the at least one further propulsion unit flowing around any wings, and thereby the air downstream of the at least one further propulsion unit produces substantially no lift.
7. The aircraft according to claim 1 , in which the at least one propulsion unit includes a propeller or fan and a contra-rotating propeller or fan configured to rotate about a same axis as the propeller or fan but in an opposite direction to the propeller or fan.
8. The aircraft according to claim 7 , in which the at least one further propulsion unit does not include a contra-rotating propeller or fan.
9. The aircraft according to claim 1 , in which the at least one further propulsion unit includes a propeller or fan and a contra-rotating propeller or fan configured to rotate about a same axis as the propeller or fan but in an opposite direction to the propeller or fan.
10. The aircraft according to claim 1 , in which the aircraft includes a divider to separate airflows from the at least one propulsion unit and the at least one further propulsion unit.
11. The aircraft according to claim 10 , in which the divider is a generally upstanding panel which is provided on the at least one wing between the at least one propulsion unit and the at least one further propulsion unit to separate the airflows from the respective propulsion units.
12. The aircraft according to claim 1 , in which the aircraft is configured to provide reduced or zero thrust from the at least one further propulsion unit once airborne.
13. The aircraft according to claim 1 , in which the aircraft comprises an elongate fuselage and two wings, with a wing extending from each side of the fuselage, and wherein a length dimension of the fuselage defines a longitudinal axis.
14. The aircraft according claim 13 , in which the at least one further propulsion unit is provided within a channel in the fuselage.
15. The aircraft according to claim 14 , in which an additional further propulsion unit is provided at a lateral outer end of each of the two wings.
16. The aircraft according to claim 1 , in which the aircraft includes at least one tail wing mounted at a furthermost part of the aircraft in the second direction and at least one tail propulsion unit mounted in front of the leading edge of the at least one tail wing, such that the air downstream of the at least one tail propulsion unit flows around the at least one tail wing to provide lift or downforce and a thrust in a first direction.
17. The aircraft according to claim 16 , in which the at least one tail wing includes at least one adjustable flap mounted on a trailing edge of the at least one tail wing, which flap is adjustable such that an amount of lift or downforce caused by the air flow from the at least one tail propulsion unit can be adjusted.
18. A method of controlling an aircraft according to claim 1 , the method comprising:
activating the at least one propulsion unit, such that an airflow from the at least one propulsion unit flows around the at least one wing to provide lift and a longitudinal thrust in the first direction;
activating the at least one further propulsion unit to provide a longitudinal thrust in the second direction that opposes the longitudinal thrust in the first direction provided by the at least one propulsion unit; and
taking off using the lift, such that the aircraft is no longer in contact with the ground.
19. The method according to claim 18 , in which the method further comprises:
once the aircraft is no longer in contact with the ground, reducing the thrust provided by the at least one further propulsion unit.
20. A method of landing an aircraft according to claim 1 , the method comprising:
increasing the longitudinal thrust provided by the at least one further propulsion unit in the second direction, such that a longitudinal velocity of the aircraft in a first direction decreases;
whilst the longitudinal velocity of the aircraft in the first direction decreases, increasing the longitudinal thrust in the first direction provided by the at least one propulsion unit, such that a steady airflow is maintained around the at least one wing; and
once the longitudinal velocity of the aircraft in the first direction has been reduced, decreasing the longitudinal thrust in the first direction provided by the at least one propulsion unit, such that an amount of lift generated by the aircraft is reduced, thereby causing the aircraft to descend.