Leeham News and Analysis
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Bjorn’s Corner: Fly by steel or electrical wire, Part 10
By Bjorn Fehrm
September 27, 2019, ©. Leeham News: In our series about classical flight controls (“fly by steel wire”) and Fly-By-Wire (FBW or “fly by electrical wire”) we started a discussion about the need for stability augmentation systems last week and how these are implemented.
We handled yaw augmentation and began the discussion on pitch augmentation. Now we dig deeper into the trickier form of pitch augmentation, the one needed because of regions of lower stability in pitch at higher Angles of Attack (AoA).
Figure 1. The pitch moment curve of a modern airliner. Source: Leeham Co.
Bjorn’s Corner: Fly by steel or electrical wire, Part 9
By Bjorn Fehrm
September 20, 2019, ©. Leeham News: In our series about classical flight controls (“fly by steel wire”) and Fly-By-Wire (FBW or “fly by electrical wire”) we discussed the FBW flight control system of Embraer’s E-Jet E2 series last week.
We have now covered examples of classical flight controls and their modern FBW counterparts. Now we discuss how these handle different stability augmentation needs like Yaw damping, Mach tuck protection or Pitch control improvements like the Boeing 737 MAX MCAS system.
Figure 1. The pitch moment curve of a modern airliner. Source: Leeham Co.
Bjorn’s Corner: Fly by steel or electrical wire, Part 8
September 13, 2019, ©. Leeham News: In our series about classical flight controls (“fly by steel wire”) and Fly-By-Wire (FBW or “fly by electrical wire”) we discussed the flight control laws of Boeing’s 777/787 and Airbus’ A220 last week.
Now we continue with Embraer’s fourth-generation FBW, the one for the E-Jet E2 series.
Figure 1. The Embraer E2 FBW system is a closed-loop feedback design. Source: Embraer.
Bjorn’s Corner: Fly by steel or electrical wire, Part 7.
By Bjorn Fehrm
September 6, 2019, ©. Leeham News: In our series about classical flight controls (“fly by steel wire”) and Fly-By-Wire (FBW or “fly by electrical wire”) we discussed the flight control laws which are implemented with classical flight controls compared with the Embraer E-Jet and Airbus A320 FBW systems last week.
Now we describe alternative FBW approaches, analyzing Boeing’s 777/787 system and Airbus’ A220 system.
Figure 1. Boeing’s 777 and 787 FBW system architecture. Source: Boeing.
Bjorn’s Corner: Fly by steel or electrical wire, Part 6
By Bjorn Fehrm
August 30, 2019, ©. Leeham News: In our series about classical flight controls (“fly by steel wire”) and Fly-By-Wire (FBW or “fly by electrical wire”) we now discuss the flight control laws which are used for Classical flight controls and FBW systems.
Figure 1. The Boeing 737 artificial feel unit operating over right rod increases roller pressure on feel unit cam, by it making displacement of both left and right rods over Elevator Control Quadrant harder (the arrows depict an elevator up command). Source: Boeing.
Bjorn’s Corner: Fly by Steel or Electrical wire, Part 5
By Bjorn Fehrm
August 23, 2019, ©. Leeham News: In our series about classical flight controls (“fly by steel wire”) and Fly-By-Wire (FBW or “fly by electrical wire”) we now look at practical implementations after discussing the authority of the flight control system last week.
As before we compare the classical 737 system to the A320 FBW system.
Figure 1. The two mechanical control pitch systems of the 737 are visible in the upper left. Each side has a complete system shown at the lower part of the figure (except for the trim which has dual wire sets but one actuator motor/drum). Source: Boeing.
Bjorn’s Corner: Fly by steel or electrical wire, Part 4
By Bjorn Fehrm
August 16, 2019, ©. Leeham News: In our series about classical flight controls (“fly by steel wire”) and Fly-By-Wire (FBW or “fly by electrical wire”) we this week discuss the Flight Control System’s authority to execute maneuvers by its different parts and why the authority of these parts is a fundamental parameter when designing the system.
Figure 1. Embraer Phenom 300’s Yaw damper rudder. Source: Embraer.
Bjorn’s Corner: Fly by steel or electrical wire, Part 3
By Bjorn Fehrm
August 9, 2019, ©. Leeham News: In our series about classical flight controls (“fly by steel wire”) and Fly-By-Wire (FBW or “fly by electrical wire”), we this week turn to the actual Flight control system after covering the infrastructure needs last week. We could see the FBW required a higher redundancy Hydraulic and Electrical infrastructure. Why we will come to.
Now we look at the control principles for classical control systems like the Boeing 737 system and FBW system like the Airbus A320 system.
Figure 1. The control axis and control surfaces of a 737. Source: Boeing.
Bjorn’s Corner: Fly by steel or electrical wire, Part 2
By Bjorn Fehrm
July 25, 2019, ©. Leeham News: In our series about classical flight controls (“fly by steel wire”) and Fly-By-Wire (FBW or “fly by electrical wire”) this week we cover the difference in system infrastructure the two controls methods call for.
We will use the Boeing 737 as the classical control example and the Airbus A320 as the FBW example.
Bjorn’s Corner: Fly by steel or electrical wire?
By Bjorn Fehrm
July 25, 2019, ©. Leeham News: Last week’s Corner which dealt with Airbus’ issue with an updated A321neo Fly By Wire (FBW) and how it was unrelated to the issue of the Boeing 737 MAX, gives a good segue to a Corner series about the possibilities of FBW versus classical flight controls when it comes to tuning an airliner’s flight characteristics.
The two different control principles present the designer with very different challenges and possibilities.
The Fly-By-Wire Airbus A321XLR. Source: Airbus.