Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- 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
- Digital twin is a key to JetZero’s hopes for Blended Wing Body entry June 2, 2025
Bjorn’s Corner: Twins or quads?
By Bjorn Fehrm
11 December 2015, ©. Leeham Co: The debate over two or four engines for long range aircraft is as old as the jet airliner. A number of myths have been pedaled over the years over the virtues of the one over the other. The myths have even been presented by airline CEOs as “facts that are known in the industry.”
Having done several in-depth comparisons of two-vs-four engined long range aircraft, we can’t find the patterns that these myths propel: that a quad is less efficient than a twin and should have higher maintenance costs. What we see is that it is all dependent on what one compares and to what technology generation the one or the other aircraft belong.
When we didn’t get the same results as the myths on a number of areas, we started to wonder what could have created the myths in the first place. Looking at what four engined airliners could have been the source of the rumours, we started to see a pattern. It was a pattern of apple-and-oranges being compared and wide ranging conclusions being drawn.
Here is what we found. Read more
The turbo-prop conundrum: small market, high costs
ATR Turbo-prop. Photo via Google images.
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Introduction
ATR and Bombardier are incumbents. China has a home-market offering.
Indonesia and India want to create a product.
It’s the 60-seat and up turbo-prop market.
It’s too many companies chasing too-small a market.
Summary
- The 20-year demand for 60-99 seat turbo-props is small.
- Developing a new, clean-sheet design is costly.
- There is a solid demand for an inexpensive 19-34 seat turbo-prop—but nobody is interested.
Bjorn’s Corner: MRJ90 first flight
By Bjorn Fehrm
13 November 2015, ©. Leeham Co: Mitsubishi flew their MRJ for the first time this week. I could have added “finally” because it is two years late compared to the original time plan. But who cares when the aircraft is finally ready to fly and everything goes well? (Well, the customers do, actually.)
It was a big moment for Japan, a nation with a sizable aeronautical industry. Japan has been a major partner to Boeing in their larger airplane programs over the 757/767 to the 777 and 787. For the Dreamliner, they even designed and made the hottest item, the high-tech Carbon Fibre Reinforced Plastic (CFRP) wing.
Despite having such a capable aeronautical industry, Japan has not built an own civil aircraft since it closed the production line for the YS-11 twin engined turboprop in 1973. Since then it has acted as sub-supplier and has worked on certain military programs like the Mitsubishi F-2 fighter, based on the Lockheed Martin F16.
The Mitsubishi corporation flew the MRJ90 for the first time Wednesday from the Nagoya Airport in Japan (screenshot from video from Mitsubishi). Most of the flight testing will be done in Moses Lake (WA), USA, where four test airplanes will be based.
Moses Lake is blessed with open skies, little air traffic, a long runway and good weather. It has a long history of flight testing, serving as a test-base for Japan Air Lines 747 pilot training for decades. Boeing also uses Moses Lake for flight testing.
We analyzed the MRJ90 and its main competitor the Embraer E175 in a subscriber article the 25th of January. We will revisit the main characteristics and then comment on what could be seen from the first flight. Read more
Bjorn’s Corner: Engine rubbing
09 October 2015, ©. Leeham Co: Last week an Airbus A320neo prototype with Pratt & Whitney’s (PW) GTF had a problem while testing hot and high conditions at Al-Ain airport in Abu Dhabi. The engine suffered a rubbing problem and PW and Airbus decided to replace the engine before returning the A320neo to Toulouse.
I had the opportunity to discuss what happened with PW people at ISTAT this week and decided it makes for a good follow up to our two other engine Corners to write about what happened and how serious it was.
The problem was compressor blades rubbing against the compressors stator wall. PW knew that this engine individual could have that problem. They saw when assembling the engine it was a bit tight in the compressor area. PW said they told Airbus there was a risk with this particular unit, and sure enough, there was rubbing to be seen when they boroscope checked the engine after the test.
Here what it was all about and what to do about it. Read more
Evaluating airliner performance, Part 2
By Bjorn Fehrm
Subscription required.
Introduction
Sep. 24 2015, ©. Leeham Co: In the second part of our series about comparing and evaluating economic and operational performance of airliners, we look at the parts beyond fuel that make up the Cash Operating Costs (COC) for an airliner.
While fuel consumption, crew costs and aircraft maintenance costs can be evaluated in a way which closely resembles reality, other costs in the COC are too complex to model in their true form.
This is the case for underway or airway fees, landing fees and station fees. Here, just about every country/airport in the world has taken the liberty to invent its own charging principles and formulas. With several hundred different formulae for these charges, the way out is to use industry-accepted approximation for these costs.
Summary:
- We establish how crew cost are modeled for our evaluation missions, taking into account the complex world of work time regulations for pilots and cabin crew.
- We also describe how we handle airframe and engine maintenance costs and how these get allocated to our missions.
- Finally, we describe how the complex underway and landing/station costs are modeled with the accepted approximations these require.
Bjorn’s Corner: USAF Tanker program
By Bjorn Fehrm
25 September 2015, ©. Leeham Co: When Scott Hamilton asked me to give my view on his article “Pontifications: Duelling refuelling tankers” I accepted. I was not involved in the project and was only following it casually over the years.
I will also not give my view on what would have been the most suitable tanker for the US Air Force. I simply don’t have the relevant military competence for that, having never operated my fighters with aerial tanking nor been in an aerial tanker aircraft.
Where I have relevant competence is in writing military specifications for important aircraft procurements and the excerpts I have seen from the tanker RFQ on key specification points don’t impress. Let me explain.
Bjorn’s Corner: Engine efficiency
18 September 2015, ©. Leeham Co: The debate around the market’s two single aisle combatants is quite heated, with fans of the one side saying “the limited space for a high bypass engine on the 737 MAX will cripple it forever” and the other side saying “the tighter design of the 737 will make it highly competitive against the A320neo, it is the A320 which has a weight and size problem”.
One of the arguments is that each inch of engine fan diameter brings 0.5% in increased propulsive efficiency. Therefore the A320 with up to 81 inches fans will win against the 737 MAX, which has a 69 inch fan. Having all the tools to check out if this is really the truth, I fed our airplane model with all the facts and looked at the result. It’s not so easy, guys…