Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- Boeing’s 737 North Line and the Everett factory: in transition now June 9, 2025
- Bjorn’s Corner: Air Transport’s route to 2050. Part 25. June 6, 2025
- New RISE powerplant benefits from decades of GE research and development June 5, 2025
- Engine makers emphasizing durability, reliability June 4, 2025
- Boeing CEO: Lessons learned are key to certification of 737-7/10 and 777X June 2, 2025
Bjorn’s Corner: Aircraft lift
By Bjorn Fehrm
March 23, 2018, ©. Leeham News: In the last Corner, we finished our series about aircraft drag, by studying an airliner flying a mission and noting how the drag changed.
Before we leave the subject of airliner aerodynamics, we shall recap how lift is produced.
Figure 1. Computer Fluid Dynamic output of a Boeing 787 during cruise. Source: Boeing and Leeham Co.
Bjorn’s Corner: Aircraft drag reduction, Part 21
By Bjorn Fehrm
March 16, 2018, ©. Leeham News: In the last Corner, we looked at the drag of an airliner during cruise. We could see the thrust required to counter the drag in the thin air of 37,000 feet was low, about 4,000lbf per engine.
Now we continue with the drag created by the aircraft during descent and landing.
Figure 1. Drag of an aircraft at different airspeeds. Source: Leeham Co.
Bjorn’s Corner: Aircraft drag reduction, Part 20
By Bjorn Fehrm
March 9, 2018, ©. Leeham Co: In the last Corner, we started to go through a typical mission for an airliner and study which drag types are important when and why.
We went through the take-off and climb phases, now we continue with the cruise phase.
Figure 1. An aircraft’s drag profile as airspeed varies. Source: Leeham Co.
Bjorn’s Corner: Aircraft drag reduction, Part 19
February 23, 2018, ©. Leeham Co: In the last Corner we wrapped up the discussion on different drag types by discussing some less dominant drags.
To finish the series we will go through a typical mission for an airliner and study which drag is important when and why.
Figure 1. An aircraft’s drag profile as airspeed varies. The main part of Parasitic drag is air friction drag Source: Leeham Co.
Bjorn’s Corner: Aircraft drag reduction, Part 18
By Bjorn Fehrm
February 23, 2018, ©. Leeham Co: In the last Corner we discussed transonic flow and drag. Now it’s time to finish the drag type discussion by adding some less dominant but still important drag types.
Knowing their origin will help us understand why aircraft are made like they are.
Figure 1. Low-pressure (green) shows areas with high flow speeds for the 787 during cruise. Source: Boeing and Leeham Co.
Bjorn’s Corner: Aircraft drag reduction, Part 17
By Bjorn Fehrm
February 16, 2018, ©. Leeham Co: In the last Corner, we discussed supersonic flow and drag. Now it’s time to talk about the drag created by transonic flow on an aircraft.
Figure 1. Pressure distribution of 787 during cruise. Source: Boeing and Leeham Co.
Bjorn’s Corner: Aircraft drag reduction, Part 16
By Bjorn Fehrm
February 9, 2018, ©. Leeham Co: In the last Corner, we discussed some further aspects of supersonic flow. Now it’s time to talk about the drag created by supersonic flow on an aircraft.
We will start with the full supersonic case this week, followed by the transonic case next week.
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Bjorn’s Corner: Aircraft drag reduction, Part 15
By Bjorn Fehrm
February 2, 2018, ©. Leeham Co: In the last Corner, we discussed the basics of supersonic flow, to prepare for a supersonic and transonic drag discussion.
We will continue the supersonic aerodynamics discussion, however, as there are some further areas needing an explanation before we move on.
Figure 1. The first supersonic airliner, the Concorde. Source: Google images.
Bjorn’s Corner: Aircraft drag reduction, Part 14
By Bjorn Fehrm
January 26, 2018, ©. Leeham Co: In the last Corner, we discussed Induced drag after having covered Friction drag and Form drag. These are the main drag components of a subsonic aircraft.
As the aircraft flies over Mach 0.5, an additional drag is added, this time based on the air’s compressibility, transonic or supersonic drag.
Figure 1. The first supersonic airliner, the Concorde. Source: Google images.
Bjorn’s Corner: Aircraft drag reduction, Part 13
By Bjorn Fehrm
January 19, 2018, ©. Leeham Co: In the last Corner, we described how the boundary layer theory lead to the understanding of Friction drag for aircraft. The mechanisms behind Induced drag was understood about the same time.
Once again Prandtl was involved, but it was an English person who first postulated the physical root of induced drag, Fredrick Lanchester.
Figure 1. Focke-Wulf Condor, a high aspect ratio aircraft from the 1930s. Source: Wikipedia.