Leeham News and Analysis
There's more to real news than a news release.
Bjorn’s Corner: Analysing the 737 MAX crashes
October 25, 2019, ©. Leeham News: To better understand what went wrong in the Boeing 737 MAX crashes I have over the last half-year run Corner series around aircraft Pitch stability and Aircraft Flight Control systems and how these attack the problems of today’s airliners need for stable characteristics over a very wide flight envelope.
With this as a backgound, we will now in a series of Corners go into the Lion Air final crash report which is issued today, to understand what happened and why.
Bjorn’s Corner: Fly by steel or electrical wire, Part 13
October 18, 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 continue our discussion of pitch stability augmentation systems when we have a mechanical (“fly by steel wire”) pitch control system.
Figure 1. The pitch moment curve of a modern airliner. Source: Leeham Co.
Bjorn’s Corner: Fly by steel or electrical wire, Part 12
October 11, 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 continue our discussion of pitch stability augmentation systems when we have a mechanical (“fly by steel wire”) pitch control system.
Figure 1. The typical pitch moment curve of a modern airliner. Source: Leeham Co.
Bjorn’s Corner: Fly by steel or electrical wire, Part 11
October 4, 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 pitch stability augmentation systems when we need to improve the pitch characteristics of a mechanical (“fly by steel wire”) pitch control system.
Figure 1. The pitch moment curve of a modern airliner when circling before landing. Source: Leeham Co.
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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.