Leeham News and Analysis
There's more to real news than a news release.
Bjorn’s Corner: Why is the real range of an airliner always shorter then what the OEM says?
By Bjorn Fehrm
07 August 2015, ©. Leeham Co: Now that we have explained the range consequences of weight and fuel limited airplane operations, we might as well explain the last important part of the range of an airliner: Why the practical range is always shorter than what the OEM says.
When an airliner OEM gives the design or brochure maximum range of an aircraft, they do that with an aircraft in a “show-room” configuration and which is loaded with a filled cabin only; no cargo is included in the calculation. Further, in the cargo area, there is only bulk-loaded passenger bags. Container loading of the bags would have cost tare weight for the containers used and weight is to be avoided when stipulating the maximum design range.
In practice, we would have to consider tare weight for bags containers and possible cargo when discussing what practical range an airline can plan for a certain aircraft model. But this is far from the whole story. Here is what has to be considered in addition.
Bjorn’s Corner: After weight or fuel limited we examine weight or volume limited
By Bjorn Fehrm
31 July 2015, ©. Leeham Co: Last week we explained what fuel limited meant and how that differs from an aircraft that has big enough fuel tanks so it can operate weight limited for its missions.
This was for fuel and it dictates to a large degree how the aircraft will behave on long range missions. When we block off seats to fly further, is it to allow more fuel in our tanks or is it to make the aircraft lighter to fly further with tanks already filled to the brim.
A similar phenomenon appears when we load the aircraft with its payload; an aircraft can take-off volume or weight limited. Here is how it works.
Bjorn’s Corner: Weight or fuel limited, what is this all about?
By Bjorn Fehrm
24 July 2015, ©. Leeham Co: In recent articles around the Ultra Long Haul (ULH) needs of Singapore Airlines, there have been many references to aircraft being either fuel or weight limited. It is not so evident what this all means and what the practical consequences are of one or the other limitation.
Let’s go through what it all means with a practical example and show how it will affect the performance of the aircraft and what one can do about it.
As an example we will pick Boeing’s ULH 777-200LR. It is known as the Worldliner since it can connect almost any two cities in the world with its ultimate range of 9,300nm. In practical use, the Worldliner has often been configured for less range. In such configurations it runs out of fuel tank space before it reaches its Max Take-Off Weight. This is “fuel limited.” Here is how it works.
Bjorn’s Corner: hot summer, hot engines
By Bjorn Fehrm
17 July 2015, ©. Leeham Co: It is summer in south of Europe and we have had over 30°C/86°F for weeks. It makes one realize the conditions where the engines have to work over their flat rating point in the Middle East.
Aircraft engines are a bit fidgety. They don’t like temperature although they are made to sustain that their hottest parts, the nozzle and first turbine after the combustor, gets scalded to 1700°C/3,092°F or more.
Go down to the very back end of the engine and we come to where the key engine parameter, EGT (Exhaust Gas Temperature), is measured. It determines a lot of things, among them the time the engine stays on wing. Things are typically 700°C/1,832°F cooler here and this is where a reliable temperature measurement probe can be placed. Based on its values, the total health of the engine’s core is determined. It is also a key input whether the engine shall be throttled back in a hot take-off like in the Middle East.
Bjorn’s Corner: Electrical flight, how real?
By Bjorn Fehrm
10 July 2015, ©. Leeham Co: We have just witnessed the first solar electrical aircraft, Solar Impulse 2, cross the ocean from Tokyo to Hawaii. Today, Friday, Airbus Group will cross the English Channel with a battery powered electrical aircraft, the E-Fan.
How real is electrical flying? Real enough to make demonstration flights like the one to Hawaii and to Calais. Both these aircraft are technology demonstrators but it is symptomatic that they do these hops now, 2015.
Airbus Group’s E-Fan aircraft is preparing to cross the English Channel. Source: Airbus.
We live in the years when electrical cars have gone from exotic one-offs to serial produced products, still expensive but more and more practical. Why should not the aircraft industry follow? Read more
Bjorn’s Corner: Bandit mask explained and nonexistent IFE boxes.
By Bjorn Fehrm
2 July 2015, ©. Leeham Co: Having aircraft as your interest exposes you to thousands of photos of your favorite subject. In general I find exterior photos of airliners a bit dull; there is no variation in their configuration or physics except for the livery of the operator. Some photos are a bit extra though. Read more
Bjorn’s Corner: What Paris Air Show taught us about East and West.
By Bjorn Fehrm
25 June 2015, © Leeham Co: With a few days in the office one can look back at Paris Air Show with a bit of perspective. So what are the impressions?
It was surprising how many orders Airbus and Boeing landed. Both had played down the expectations, telling that it will be a decent show but nothing close to record. Yet both were booking orders or commitments which were better than expected going into the PAS. Read more
Bjorn’s Corner: Paris Air Show review
By Bjorn Fehrm
June 18, 2015, c Leeham Co: With the industrial part of Paris Air Show over (the public portion continues through the weekend), one can start to summarize impressions. I have over the years participated in around 10 Paris Air Shows or Farnborough International Air Shows. This was one of the first where one could see that people were stopping and looking up to observe the aircraft which were quiet.
Bjorn’s Corner: Hot competition in Middle east.
By Bjorn Fehrm
- Boeing needs hundreds of 777 orders to bridge the production gap is now open to all Readers.
By Bjorn Fehrm
Introduction
12 June 2015, C. Leeham Co: Earlier in the week we had an interesting interview with Sir Tim Clark, , president and COO of Emirates Airline. We discussed Emirates’ requirement for a twin aisle medium/long range complement to their Airbus A380 and Boeing 777 fleets. The competition is between Boeing’s 787-10 and Airbus’ A350-900. So far the assumptions have been that the 787-10 will be hard to beat on pure costs per seat for mid-range requirements in the 300-seat segment.
The 787-10 seats 323 passengers in Boeing’s old-fashioned IAC three class seating and 331 in our more modern, normalized two class seating with 60 inch angled lie flat in Business and 32 inch economy section. The A350-900 has so far seated 313 seats in the same normalized seating standard. Recent cabin changes by Airbus can now increase that to close to 330 seats. The configuration changes were originally conceived for A350-1000 but we believe Airbus will offer these to Emirates and they will make it into the -900 catalog.
The 787-10 is lighter and would therefore be more effective on fuel but the difference is small, given the A350-900’s more modern engines. So the overall discussion was that 787-10 had found its ideal customer, in need of many seats, a solid mid-range performance and lowest cost. That was until Monday’s interview with Clark.