Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- Boeing First Quarter Results Update: China is 10% of the backlog, with 500 in “Unidentified” April 24, 2025
- Boeing First Quarter Results: Tariffs, Return flights, $10.55bn asset sale April 23, 2025
- RTX Q1 2025 Earnings: GTF Talk Takes A Back Seat To Tariffs April 22, 2025
- Tariffs Tumult Takes Over GE Aerospace Q1 2025 Earnings Call April 22, 2025
- Boeing reports mixed results of latest employee survey, but middle management and officers remain key obstacles April 22, 2025
Bjorn’s Corner: Pitch stability
By Bjorn Fehrm
November 23, 2018, ©. Leeham News: In the spring I ran a series of Corners which dealt with aircraft stability on a basic level (April 13 to June 8). It covered the aircraft’s basic stability modes in normal flight and described the basic helper systems one finds on aircraft, such as yaw dampers and autopilots. But we did not go deeper into aircraft stability problems and more advanced helper systems.
Given recent events, it can be interesting to dive a bit deeper into the pitch stability of an aircraft and common helper systems.
Figure 1. The Boeing MAX 8 which introduced the MCAS system to help with pitch stability. Source: Boeing.
Bjorn’s Corner: Supersonic transport revival, Part 14
By Bjorn Fehrm
November 9, 2018, ©. Leeham News: In last week’s Corner we compared the GE Affinity, the Mach 1.4 engine for the Arion AS2, to the engine of the Concorde when both propel a Mach 2 Supersonic Transport.
We could see an engine must be designed for working at Mach 2. The Olympus, now a 50-year-old design, was more efficient in propelling a Mach 2 SST than the hypermodern Affinity. Now we design a custom Mach 2.2 engine.
Figure 1. A Mach 2.2 suitable SST turbofan modeled with GasTurb. Source: GasTurb.
Bjorn’s Corner: Supersonic transport revival, Part 13
By Bjorn Fehrm
November 2, 2018, ©. Leeham News: In last week’s Corner we looked deeper into the fundamentals of the Mach 1.4 engine of Aerion’s AS2 SST, the GE Affinity.
Now we start looking at engines for a faster SST, up to the Mach 2.2 of the Boom Supersonic project.
Figure 1. The GE Affinity medium bypass Turbofan for Aerion AS2. Source: GE.
Bjorn’s Corner: Supersonic transport revival, Part 12
October 26, 2018, ©. Leeham News: In the previous Corner we discussed the noise challenge an SST engine has. To be effective at Supersonic speed it needs a high Specific Thrust (a fast jet out the back) but this creates Takeoff and Landing noise.
We now look at some key data for SST engines.
Figure 1. The GE Affinity medium bypass Turbofan for Aerion AS2. Source: GE.
Bjorn’s Corner: Supersonic transport revival, Part 11
October 19, 2018, ©. Leeham News: In the last Corner we discussed the temperature challenges an SST engine faces.
Now we address an even larger problem for SST engines, the takeoff and landing noise.
Figure 1. The GE Affinity SST Turbofan for Aerion AS2. Source: GE Aviation.
Bjorn’s Corner: Supersonic transport revival, Part 10
October 12, 2018, ©. Leeham News: In the last Corner we discussed the challenges of the nacelle outlet for an SST (SuperSonic Transport). Now we will discuss SST engines and what are the key technical challenges for these engines.
We start this week by looking at some design constraints for the engine which we don’t have in Subsonic airliner engines.
Figure 1. A generic mixed Turbofan SST engine with ConDi nozzle. Source: GasTurb. Read more
Bjorn’s Corner: Supersonic transport revival, Part 9
By Bjorn Fehrm
October 5, 2018, ©. Leeham News: In the last Corner we discussed the challenges an efficient inlet poses for an SST (SuperSonic Transport).
Now we go to the back of the nacelle and look at the outlet.
Figure 1. The Concorde nacelle with intake and nozzles. Source: Google images.
Bjorn’s Corner: Supersonic transport revival, Part 8
By Bjorn Fehrm
September 28, 2018, ©. Leeham News: In the last Corner we started looking at the biggest challenge for an SST, the powerplant. We first discussed the most fundamental problem of the engine, the level of Ram drag for an SST engine.
Now we continue with the challenges of the Nacelle. This week we talk intakes.
Figure 1. The Concorde nacelle with its Multi-Shock inlet. Source: Google images.
Bjorn’s Corner: Supersonic transport revival, Part 7
By Bjorn Fehrm
September 21, 2018, ©. Leeham News: In the last Corner we looked at the heating of the aircraft when cruising at high Mach.
Now we will address the biggest problem for supersonic airliners, the engines and nacelles.
Figure 1. The Concorde engine and nacelle. Source: Google images.
Bjorn’s Corner: Supersonic transport revival, Part 5
By Bjorn Fehrm
September 7, 2018, ©. Leeham News: In the last Corner we looked at the drag hump which is created by several supersonic effects when an SST (SuperSonic Transport) passes Mach 1.
Now we will look at other aerodynamic problems facing an SST.
Figure 1. The Aerion AS2 SST with its main systems. Source: Aerion Supersonic.