Bjorn’s Corner: New aircraft technologies. Part 26. Airliner development program

By Bjorn Fehrm

August 18, 2023, ©. Leeham News: We started last week to look at how to make the development of a new airliner family more efficient.

First, we describe how development projects are phased and how many people with what competencies are engaged in each phase. Then we can start the discussion of what changes can be made and what would be the consequences.

Figure 1. The JetZero Blended Wing Body that USAF partially funds to prototype. Source: USAF and JetZero.

The development program

Before we discuss how to make the traditional airliner development program more efficient, let’s look at what phases a program has, what is done, and how many people are involved at the OEM in each phase, Figure 2.

In addition to the OEM’s people, there are thousands of employees at suppliers working on the project once it gets going.

Figure 2. A typical new airliner family development plan. Source: Leeham Co.

Conceptual design

A development program starts with a Conceptual design phase. It can be from a year and up to several years in length. Typically it transforms a continuous company research into new technologies and configurations to a more focused analysis of a few design candidates and how well these respond to the market segment needs that the airliner project shall satisfy.

The market segment needs are built by the OEM’s market and sales department in cooperation with customers, typically in a Customer reference board that is established as a project enters a conceptual design phase.

Let’s assume we shall develop the next-generation airliner for the heart of the market segment, today served by the Boeing 737 MAX 8/10 and Airbus A320/A321.

In the conceptual phase, you test different concepts and technologies against the market specification that the project shall meet. You also present the concepts to the Customer reference board to get feedback.

We could, for instance, have one conceptual candidate that is a BWB concept (now that the US Air Force has part-financed a prototype BWB from JetZero that shall fly in 2027. This will forward this technology from a “yes, but…” situation to a real candidate for future air transport projects. Good stuff!), and we want to know if airlines could accept such a concept and what problems to its introduction they would see.

Other presented candidates would be conventional tube and wing, with folding wingtips and a third a Truss Braced Wing concept. How these fulfill market segment requirements is discussed with the customers, and their feedback is collected.

In the concept phase, the concepts are analyzed by a small group of people (in total, around 50 engineers, plus many more at sales and marketing) using preliminary design tools. We will discuss the tools and work methods for each phase in the following articles.

Preliminary design

After Conceptual design, one or two candidates go to Preliminary design. Now the performance and cost data for the candidates are developed so that performance guarantees and prices can be established. These are presented to the Customer reference group and to potential launch customers.

When the information is solid enough, and customers are ready to order the aircraft, an “authority to offer” and program launch is done. In the preliminary design phase, the team has expanded to hundreds of specialists in different disciplines. Data is still on an aggregated level but detailed enough so the aircraft with its different systems can be specified. The data would include;

  • Aerodynamic performance
  • Engine thrust needs
  • System configurations with overall specifications
  • Cabin and cargo area layout and capacity
  • Weight data on a build group level
  • Estimated cost for each build group and system
  • Operations and Maintenance characteristics for aircraft and systems
  • Production costs for the aircraft

After launch, the preliminary data goes through different refinement steps, which culminate in an aircraft design freeze.

Detail design

The freeze triggers the largest work item, detail design. A modern airliner is made of about four million parts. Some of these are standard parts like fasteners, tubes, etc., but most are custom designs. Thousands of designers start the arduous job of designing all structural parts in CAD and enter all the design data for parts and systems in the PDM (Product Data Management) database.

The software for the different systems, which is an ever-increasing part of a design project, gets developed.

Sub-suppliers are chosen and start their design work to adapt existing system components or design new ones for the aircraft.

Prototype manufacturing

Once the detailed design has converged to a “release for test or prototype production” stage, the parts for the aircraft OEM’s systems rigs or prototypes are ordered.

System parts go to system rigs where the aircraft’s different systems, like air conditioning, hydraulics, electrical systems, avionics, landing gear, etc., are tested.

The parts for the prototypes are assembled by hundreds in mixed engineering and factory teams, which gradually build the prototypes.

Testing and certification

When the testing in the system rigs has reached a sufficiently mature state and the prototypes have been tested and flown by the company to a level that is ready for certification, the regulator’s teams are invited to test the aircraft to verify it complies with the specifications, and test plans the OEM and regulator have agreed on.

Production preparation

All the parts for the aircraft are analyzed for serial production suitability by production engineers. When testing of systems and prototypes has shown the designs to be ready for production, the production-level specifications are sent to suppliers. This starts the production phase of the program.

Entry into service and fleet support

The training and service departments prepare the hundreds of simulators, manuals, and databases that have to follow the aircraft at Entry Into Service, EIS. The operational aircraft start their journey in the tightly surveyed maintenance phase, where all operational data is collected and worked on to identify any changes needed for later deliveries.

Discussion around each phase

We will go through these phases and look at the work done and the tools used. Then we will discuss what possibilities there are to speed up the work using new techniques and methods and what problems must be overcome to do such changes successfully.

36 Comments on “Bjorn’s Corner: New aircraft technologies. Part 26. Airliner development program

  1. There are almost always cost and weight reduction programs popping up a few times changing the design. Requirements creep where different sales managers promising airliners more makes design freeze a floating issue, letting cost and time glide away. Late flight testing problems adds to the mix and often money starts to runs out and you need to reduce the headcount too soon. It sound like the PW1100G and its cousins are a good case study of all this.

  2. One thing I would add is that it’s not necessary to go through all these stages step-by-step for an entire aircraft in one go – large sections or components may go through their own conceptual/protoyping/testing stages to try things out before they become an option for a new or upgraded aircraft.

    In this way there may be many, many different ideas for wings/engines/undercarriage/etc. going through many different stages of the design process completely outside of an aircraft programme – but some will end up being chosen for new/upgraded aicraft. Their development may already be largely complete by this time so stages can be skipped or reduced during the aircraft programme.

  3. I’m thrilled that the USAF has ordered a full-scale prototype of the JetZero Z-5 BWB airframe! – Super exciting!

      • Interesting aspects Northrup Grumman is a supporter of the BWB.

        NG has different divisions of course, so some is possible weapons support and Scaled Composites supposedly take a major role.

        Why the strange lash up I have not see anything on.

    • JetZero has 46 employees.
      Is it planning on pinching vast numbers of employees from other aerospace players (using funds that it doesn’t have)?
      Or is it going to outsource development and manufacturing to some other entity (which currently doesn’t exist)?

      Sounds a lot like Boom (150 employees)…

      • @Bryce

        Agreed. Reviewing JetZero website they’re based in LGB, California. It’s an extremely tough environment to recruit top talent in this market with the cost of living/taxes.
        The logistics of designing/building/certification are enormous. I wish them luck but IDK.🤷‍♂️
        When I see the self induced problems an established company such as Boeing has incurred the last 20 years it will be interesting to watch JetZ.

        I do like this BWB concept much better versus this dream of a TBW that Boeing is conceptualizing especially for airline ramp operations.

      • They might let Northrop/Scaled Composites do all the work for a Northrop “Epsilon”. Most likely do they have lots of BWB experience from the B-2 and B-21 that they can carry over. Its a demo, not a fully analyzed/optimized airliner with 1000’s of engineers and purchasing/productions specialists involved spending $2bn/year. That will come later if they succeed this time around.

        • also, remember it doesn’t need a commercial certification. it is an X plane, it will get an FAA Experimental cert.

      • all the engineering and manufacturing is going to be done by Scaled Composites.

        Jet Zero is a marketing entity with a couple Chief Engineer types.

  4. Bjorn,
    I hope that you have a whole chapter on supplier selection, supplier capability and capacity, and supplier management. While not publicly acknowledged, the costly delays in 787 program were in-part due to inability of suppliers, especially specialty fastener manufacturers, to ramp production to support initial build and rate increases, and the lack of capability in tier 1 and sub-tiers in composite materials and processes. MBD and digital twin techniques have their place but are no panacea. Business 101 is making sure that your suppliers can execute what they are tasked to do.

    • There is a big difference of which suppliers you choose especially if they will design their parts. Boeing top program management back then seems to have been unaware of how much control Boeing engineering and project mgmnt was needed at suppliers and their key suppliers to make sure they delivered per contract.

  5. I would amend a couple of parts of the report.

    While it is airlines who order, its also their perfection of what the public will accept that gets involved and that is a tough call. RISE with the prop would be one.

    While JetZero is creating a test article, I don’t even know its a true prototype.

    And the major aircraft mfgs don’t really do prototypes, they are early builds and if they can, are sold. Boeing had a couple 787s that they did not sell (too much odd stuff).

    Airbus sold all the early A350 though at hull 18 the A350 underwent a lot of changes.

    • Spell check does not catch a right spelling and I won’t use the context thing as I tried to force me into Microsoft Dark Side of what it thinks is right.

      Ergo, perfection should have been perception.

      • I dunno, the Airlines have pretty much perfected their ability to sell the worst possible product that the market will bear.

        • That is one of those, sort of.

          They have perfected the art of getting people to pay as much as they can, with an offer of cheap seats to start with.

          Ergo, those cheap seats are filled one way or the other, upgraded if possible, if not, then cheap, planes are full.

          But, if people won’t fly in a prop job? Then you fill few if any seats.

          And there in is the issue, would people fly in a TTWB? BWB (maybe more likely). If it looks different, then we get into the chicken and egg thing where is any airline willing to see if they can get a egg to be a chicken. Or if the chicken is a rooster you ain’t getting no eggs.

          We know people don not like prop jobs and may well shift to an airline that offers jets (they might even pay more)

          Its going to take a brave airline to be the first.

          Once you prove something, then next is no issue but will someone volunteer to be first?

          Of does Boeing offer a free TTBW to an airline on a trial basis?

  6. I thought Airbus had a blended wing option for heart of the market replacement? With some work in the Netherlands?
    Not in this report?

  7. One of the reasons given against BWB designs is that they are not easy to stretch, but is there any reason why the fuselage fore and aft of a BWB centre section could not be used, to allow those sections to be adjusted in length to suit requirements?

    • I was wondering the same thing, how could they offer different sizes. I think it would depend on seating configuration inside, but since the body is a lift surface, you would likely have to do more work to ensure the aerodynamics are the same vs a traditional plane. Personally seems like a bridge too far to go from tube and wing right to this but I suppose if it’s more efficient by a long shot maybe. TBW seems like a middle ground especially if it used turbofans then the RISE type prop-fans. I also wonder how much cargo it would take and how much parking space it would occupy, right now cargo is more of a shape byproduct whereas the plane would have to be thicker to support the same volume, maybe it would change the flight trajectories or the cargo market?

      • They slice along the longitudinal axis of the air frame and insert a fillet to make it wider. The analogy would be to make the span (of the wing) longer.

        A greater problem (with the configuration shown) is at high alpha, the air going into the engines would become turbulent. Work was done here in the UK to address this; the solution was to bury the engines in the frame and perfect boundry layer ingestion to feed the engines clean flow at any alpha, even stall.

        • Or they just scale it, making fuselage and wing bigger. With robotic composite build and plugs in the lay-up tooling for the ATL machines. Keeping engines, cockpit, doors, APU, Air cycle machines, electronic boxes, actuators and landing gears almost the same bolting them into similar fittings in the bigger shell/wing structure.

      • @Scott

        Thanks for this history.
        Ok but the TBW is the future 🤷‍♂️

        I know I know….. think outside the box. 🙄
        Then again NASA is paying the bills.

      • I am frustrated that the work of NASA’s Albion H. Bowers et al is never given the attention it deserves. He proved Prandtl’s lost thesis that spanwise distribution was not the ideal lift solution. He named his solution the Prantl-D wing.

        His wing and the resultant elimination of adverse yaw, actually introducing proverse yaw, eliminates the requirement for a tail/rudder assembly. The tail plane assembly on a B737 weighs around 3.5 tonnes. The resultant aircraft has quite a long wingspan with up-wash at the wing tips but absent of a tail-plane, is otherwise fairly convention (no pedals in the cockpit though) but at least a 12% more efficient wing with a total machine efficiency increase of 69%. The wing tips can be manipulated to create thrust, overcoming the asymmetric thrust condition problem.

        The same theory applied to propellers results in the same thrust but much less noise and similar efficiency gains.

        You can buy RC model gliders with Prantl-D wings, it works, I have three.

        A Prantl-D winged airliner, perhaps with Prantl-D props is the most elegant solution for any new airliner.

  8. For the Boeing 787 conceptual design, preliminary design, detail design, prototype manufacturing, supply chain realization, testing and certification and production preparation costed about $20 Billion/ 8 years.

    This JetZero Blended Wing Body is much more innovative, challenging, so would probably cost more and take longer. But that’s for the real world only 😉

    • except this is an X plane, not a certified civil airliner. a one off prototype, and will be built by a company (Scaled Composites) who’s only business is building one off prototypes for shockingly little money.

      • That is not correct.

        Jet Zero is the prime, Scaled Composites is a associate or a sub contractor (depending on what the NG relationship to Jet-O is.

        I also do not think the BWB is more challenge, its different, but high wing truss braced aircraft are new for a LCA.

        No one has done a TTBW either.

        • Jet Zero has 48 employees, most of whom are executive types, they are not building _anything_.

          they have a couple (very experienced and capable) chief engineer types who may be driving the high level design, but detail design and fabrication will all be done by Scaled.

  9. Great to see JetZero’s BWB and Boeing’s TTWB.

    -> 2 different solutions/proposals for the next 60-70 years. Aeronautics and American industry are finally reborn.

  10. The engine configuration of the JetZero Blended Wing Body showed above, probably makes it hard to certify it as a twin engined aircraft, because of the risks an uncontained engine failure taking out the other engine too. And there a ton of other inconvenient requirements that prevented BWB’s passing the concept phase over the last 70 years.. But when there’s billions of stupid capital & environmental fear in the market, amnesia kicks in everywhere.

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