Leeham News and Analysis
There's more to real news than a news release.
Bjorn’s Corner: Flight control, Part 4
By Bjorn Fehrm
1 April 2016, ©. Leeham Co: Last week we described the computer augmented flight controls that are possible with Fly-By-Wire (FBW) systems. We described the most common flight control laws by discussing the two most common control law implementations in the market, the Airbus and the Boeing ones.
Today we will finish the series by discussing how an autopilot, or as the OEMs call it, an Autoflight or Automatic flight system, is added to the aircraft’s control system. An autopilot is most of the time combined with a flight director and a Flight Management System (FMS).
We will mention how these fit in the picture but focus on the autopilot, once again to keep it simple and avoid trying to cover too much. The autopilot subject is large enough. Read more
Bjorn’s Corner: Boeing’s 787 and Airbus’ 350 programs, a snapshot
By Bjorn Fehrm
Introduction
23 April 2015, C. Leeham Co: It has been an eventful week for Boeing with Q1 results reported and with that an update on the 787 program. At the same time we ran into Qatar Airways CEO Akbar al Baker, while visiting Airbus the other day and could exchange a few words with him and his team re the A350. I therefore decided that this week’s Corner should provide a snapshot on where these two new aircraft projects stand right now.
A321neo configurations and A320 production
By Bjorn Fehrm
18 Jan 2015: As part of the preparations for the Airbus A321LR article 15 Jan. we saw a need to clarify with Airbus the production configurations for A321neo. There had been several iterations of what will be produced come mid-2018 when the A321neo variant is scheduled to roll off the FALs at Airbus in an enhanced Airbus Cabin-Flex (ACF) variant.
This variant features a three-door pairs layout that allows a raised max passenger limit by virtue of displaced door three and an addition of a second overwing exit. Recent media articles have suggested that both the initial four-door variant as well as the three-door variant would be available.
Airbus formally launches A321LR; we look behind the “LR” to see what’s there
15 Jan 2015: Airbus officially launched what to date has been called A321neoLR as the A321LR at their annual press conference Tuesday. The former A321neoLR name was formed by Leeham News on 21 Ocober 2014 when we could reveal the existence of a A321neo variant which Airbus had
started to present to airlines at the time. The final name kept the LR attribute used in the article to distinguish the longer range variant from the standard A321neo.
The A319 has used the LR designation but its use has been limited. The suffix is more commonly identified with Boeing, used as it is with the 777-200LR. Boeing has also commonly used the ER for extended range like 777-200ER, 737-900ER and 777-300ER.
Airbus reveals record orders at annual press conference
By Bjorn Fehrm
Toulouse 13 Jan 2015: Airbus today held their annual press conference where they among other things revealed their final numbers for orders and deliveries. The press conference was hosted by Airbus CEO Fabrice Bregier accompanied by COO Customers John Leahy, new COO Tom Williams and new Head of Programs Didier Evrard.
Airbus in 2014
Bregier started with pointing out that 2014 was a very eventful year for Airbus. Airbus did their customary end of year sprint and passed Boeing for net orders with 24 aircraft netting 1456 commands, Figure 1.
Figure 1. Airbus orders for 2014. Source: Airbus.
On the delivery side Boeing is ahead with 723 deliveries versus Airbus 629, Figure 2.
Figure 2. Airbus deliveries for 2014. Source: Airbus.
Further Airbus certified the A350 and delivered the first aircraft to its launch customer, Qatar Airways. It also launched the A330neo and got 120 orders during the year. Finally they flew the A320neo first prototype.
A380neo decision likely this year, triggering the next widebody engine project
Subscription required
By Bjorn Fehrm
Introduction
Jan. 12, 2015: One of the subjects which is sure to come up on Airbus annual press conference on Tuesday the 13th in Toulouse will be when and how Airbus will re-engine the A380.
Airbus Commercial CEO Fabrice Bregier vowed during the Airbus Group Global Investors Day last month that an A380neo is coming.
There is much speculation around this subject as the business case of re-engineering an aircraft that is selling at such low numbers is difficult to get to close. The business case is difficult to make work for Airbus (such a project will cost in the order of $2 billion) but it will be equally hard for the engine manufacturers to offer engines that have enough efficiency gain to make the overall project feasible from an efficiency improvement perspective.
Summary
- A380 Classic equals Boeing 777-300ER seat fuel costs.
- Boeing 777-9 beats A380 on CASM, an A380neo regains the advantage.
- Engine makers face hard choices to retain dominance or to broaden market penetration.
Fundamentals of airliner performance, Part 5; Approach and landing
By Bjorn Fehrm
Dec. 2, 2015: The time has now come to cover descent and landing in our articles around airliner performance. As many aspects of descent are similar to climb we will repeat a bit what we learned in Part 4:
- For high speed operation the pilots fly on Mach as this gives him maximum information around possible effects on the aircraft when he is close to the high speed limit, the maximum Mach number. Beyond this the aircraft gets into supersonic effects like high speed buffeting or unsteady flight.
- For operations under the cross over altitude for Mach 0.78 to 300 kts IAS the pilot flies on Indicated Air Speed (IAS) which gives him maximum information how the aircraft reacts should he go close to the aircraft’s lower speed limits.
Lets now start to go through the steps that our 737 MAX 8 performs after leaving its cruise altitude.
Happy Thanksgiving, 2014
Today we’re watching the Seattle Seahawks…Go Hawks!
We’re off until Monday.
Fundamentals of airliner performance, Part 4
By Bjorn Fehrm
Nov. 25, 2014: In our article series around the performance of a modern airliner we have now come to the climb after takeoff. We started with cruise as this was simplest because the aircraft is flying in steady state, then we looked at the modern turbofan and how this is affected by both altitude and speed. We then examined how this affects the takeoff and today we continue with the climb after takeoff.
Before we start, let’s sum up a few points we need for today:
- Drag is the one thing we always need to be aware of as this regulates how much excess power we have in different flight situations and therefore if we can stay on our altitude or climb.
- Drag diminishes with altitude as the airs density diminishes and thereby our dominant drag component, air friction against our aircraft’s skin. This is the major component of the aircraft’s dominant drag, parasitic drag.
- Our lift force is generated by forcing air downwards and this causes induced drag as this downwash cost energy to generate and maintain. Induced drag is mitigated by a wing with a large span.