CFM announces the RISE engine program

June 14, 2021, © Leeham News: GE and SAFRAN took to the stage today to announce the extension of their CFM joint venture to 2050 and the CFM technology program RISE.

RISE stands for Revolutionary Innovation for Sustainable Engines, and it elevates previous work to new levels and introduces some news.

Figure 1. The RISE Open Rotor engine as presented by CFM. Source: CFM.

Open Rotor revisited

RISE (Figure 1) takes the GE/Avio developed single Open Rotor concept from Clean Sky project IRON (Figure 2) and marries it with SAFRAN’s open rotor knowledge. The result is a new start for Open Rotor with the market’s largest engine OEM, CFM, behind it.

Figure 2. The Clean Sky IRON project’s GE/Avio Open Rotor engine. Source: Leonardo.

We have presented the base concept, the tractor single Open Rotor with second stage de-swirling vanes here. It was then part of the EU’s Clean Sky 2 program. People in Clean Sky tipped us that this was something new and smart, so we visited the IRON program’s headquarter in Turin last year to discuss the concept.

It keeps the advantages of Open Rotor but simplifies the mechanics to a single rotor from previous projects’ two. In its base, it is not more complicated than a turboprop engine with added variable incidence de-swirling vanes.

What’s new is GE and SAFRAN will fully develop this concept in their CFM joint venture. CFM is our largest engine OEM today, both in terms of delivered engines (over 30,000) and engine deliveries (several thousand CFM 56 and LEAP engines per year).

Hydrogen version

The development will span some 15 years, with engines ready for prime time by the mid-2030s. The RISE engines will be developed in Jet fuel/SAF and hydrogen burning versions. The latter is the real news in the announcement.

Making a gas turbine run on hydrogen is straightforward (read about it here) and is the shortest and most realistic way to lower air transport emissions of greenhouse gases. It eliminates CO2 emissions and reduces NOx emissions by 80%.

Another technology we have written about is the motor-generator that will be integrated into the new engine core. To call this “hybrid technology” is a bit of a stretch. Previously it was called “an integrated starter-generator,” which is what it is.

It’s an elegant way to combine the engine air starter and the engine-driven aircraft generator into one. Its placement on the core’s main axis can help the engine during revving up and down. This allows the engine’s internal aerodynamics to be further tuned towards efficiency. It can also deliver electricity to the aircraft but so can the generators on the engines of today. They are just placed on the engine’s auxiliary gearbox.

Easier aircraft placement

The final twist of the engine is an optimization of the rotor towards a smaller diameter. It has two advantages: It eases the installation of the engine on the aircraft. Whereas the large rotor of previous projects prescribed a rear placement, the smaller diameter version now enables more placement alternatives (Figure 3).

Figure 3. The smaller diameter Open Rotor of RISE eases aircraft integration. Source: CFM

The second advantage is the engine is less sensitive to higher speeds. The reduced diameter reduces the engine’s bypass ratio (in technical speak it increases the specific thrust). It puts the RISE engine’s high-speed characteristics closer to high bypass turbofans, which in turn makes the engine suitable for airliners that fly longer routes, up to our typical single-aisle routes.


So is RISE Open Rotor revisited? Yes, but in a positive way.

The RISE Open Rotor is further tuned for simplicity and reliability, and the bypass ratio is moderated to retain thrust at higher speeds. It also comes in a hydrogen-burning version which is the announcement’s real news.

Hydrogen fueled Fuel Cells feeding electric propulsors might be the ultimate future hydrogen propulsion architecture, as this eliminates the NOx emissions in addition to CO2. But their development for airliners will be long and difficult. Hydrogen-fueled gas turbines are a practical and vital step towards our ambitious 2050 goals for lowered emissions for air transport.

58 Comments on “CFM announces the RISE engine program

  1. Wondering if there have been advances in the containment of the propeller since the
    7J7; IIRC that was at least a claimed sticking
    point then.

    Also: might there be a loss of propulsive efficiency
    from the new, smaller propellers?

    • ‘loss of propulsive efficiency from the new, smaller propellers?’
      Graphics arent everything but there seems to be more blades

      • It’s a relative term I think. Half the blades are variable incidence stator blades and the other half(approx.) are variable incidence rotor blades. Is the rotor the propeller or is the whole thing a propeller?

        The technology might do well in the e-VTOL field.

      • OK, I think I get you. Your saying blade area has stayed the same as previous proposals.

    • Both from the point of view of passenger acceptance and the effect of a propfan blade disintegration the tail mounting would seem to be best. Having said that a passenger was killed on a DC-9/MD80 because they did cram a passenger seat there. The concept model however doesn’t show that.

      • I had a seat back there one time. Asked for a Window and got a grand view of the front of the engine! (and noisy, sorry I was)

        That said to do a tail mounted engine costs heavier structure and that all has to weigh in on the overall package of an Open Rotor as just test stand efficiency does not cover the package

        And as noted elsewhere, a one off engine choice does not sit well (given Boeing has done it but the CFM-56 was an amazing engine reliable and SFC wise) still have to see how the LEAP compares long term.

        You can gain SFC and loose on the maint or reliability end or both.

        When P&W made a decision for a tech jump, they went with GTF not open rotor. I think that says a lot about where it goes.

        I am not against government support for tech, but when it directs the tech in a specific direction then you no longer have a open decision.

        The last NASA studies I saw all were GTF based.

        • Interestingly if you look closely at that model by Leonardo you see the engines mounted in pods suspended of the stabilizer. Look closer there is what looks like camber on the stabilizer. Is there an attempt to overcome the disadvantages of tail mounting by creating lift? Doesn’t make sense from a stability point of view but at least the stabilizer does double duty.

    • yes, lower propulsive efficiency (see statement about specific thrust in the article and bjorn’s corner series on turbofans, the whole point of increasing fan diameter in UHB turbofans is increasing propulsive efficiency at the expense of specific thrust)

      but “lower” is a relative term, it will still have much higher propulsive efficiency than even the best of the current shrouded turbofans

      • But how much and is it enough for other offsets?

        All good thoughts and questions.

        I have watched it since the 80s and don’t see the case. Not the first time I would be wrong.

    • Look up GEs previous open rotor design, this seems to be a development on that design with changes mentioned.

      • Another repackaged blast from the past with loose ends tightened. One may read all about the story of PropFans’ hyped genesis, evolution & ultimate abandonment, like the trough of disillusionment of the Gartner’s Hype Cycle, in the 1980s which doomed the Boeing’s 7J7 and effectively cleared the way for the rise & dominance of the Airbus’ A320 family in the narrow body market.

        • > Another repackaged blast from the past with loose ends tightened. <

          I see it similarly: lots of PR floating around today, in many areas. Thanks for the link to that book, which I'll likely buy.

        • “which doomed the Boeing’s 7J7 and effectively cleared the way for the rise & dominance of the Airbus’ A320 family”

          you really think that that had significant causality linkage?

          • Ted:

            If its got gears then no longer Open Rotor it becomes a variation of a Turboprop, much like the A400 that has (and chose) those.

            Turbo Props while more efficient also have their maint aspects so like all of it, there is a balance and where it falls gets to be trade offs.

            Prop maint on top of the engine itself and more complexity.

          • Possibly, the early proposals for what became the A320 did start of as open rotor propfans and maybe scimitar props, fortunately they were abandoned by Airbus.

            According to Wikipedia
            “During the A320 development programme, Airbus considered propfan technology, backed by Lufthansa.[12] At the time unproven, it was essentially a fan placed outside the engine nacelle, offering speed of a turbofan at turboprops economics; eventually, Airbus stuck with turbofans.”

            Reference 12 is “Aris, Stephen (2002). Close to the Sun. London, UK: Aurum Press Ltd. pp. 119–126. ISBN 978-1-85410-830-2.”

            Thankfully Airbus abandoned this waste of time.

  2. This reads like a pure PR statement (aka Boom)

    I am not buying it. Still an open rotor or a turboprop and people do not like those.

    Add in placement (rear structure beef up makes it heavier than pylon wing)

    Like the Hydrogen program, the only reason its happening is the EU putting money into it as a tech program.

    I am willing to get that like RR on the Ultra Fan its got a lot of internal tech from the Advanced that can be used regardless and free research money.

    • > This reads like a pure PR statement (aka Boom) <

      Maybe not a coincidence: there's typically lots of new vaporware around as things fall apart.

      show me

    • “Still an open rotor or a turboprop and people do not like those.”

      To be honest, that’s mainly an American ‘thing’. The rest of the World has no issues with turboprops.

      • I will disagree, though I grew up with props and have no problems with them.

        But if Alaska Airlines has a problem with a Turbo Prop between the two largest Alaskan Cities (small) in a place that is seriously into Aviation (by far more aircraft than anywhere else), then it gives me pause.

        While ATR is doing ok, Airbus does not want to put anything into it as its low sales. I see more and more regional jets being sold.

        It would be interesting to see the totals though right now trends will be disrupted.

        • So you disagree that it’s “an American thing”, then cite an American example…

          The fact is that turboprops are used around the World without any of the reluctance that we see in America.

          • Stealth66:

            I did, so why the aggressiveness?

            Turbo Props are used in the US a great deal. But its smaller operations.

            Have you ever seen anyone design a A320/737 with Turbo Props?

            Airlines also look at this and there are other trade offs maint and complexity wise for a turbo Prop.

            You don’t see ATR or DH selling massive numbers do you?

            What I am saying and being polite about it, is look at the number of say Embraer in the E series vs ATR and DH.

            Alaska Airlines recently cut a lot of Dash 8 (about half) and shifted to Embraer. I don’t think it all is passenger preference.

            You need to get into the weeds on TBO on the Turbo Prop, prop maint, gear box added and then the cost of a Jet engine.

            Airbus won’t put money into ATR for a new Turbo Prop (and my take is the move on hydrogen is because of government money pushing it there.) I don’t fault Airbus but it gets interesting when a solution is imposed that way.

            I think people world wide take what they can get and in some cases a Turbo Prop is it.

            But production number and investment wise, its has been and I don’t see it changing to jet engines as the first choice for airlines and the airline mfgs put there money into jets.

            The A400 is an exception but that is a tactical airlifter and the military requirements are the driver performanceT wise not the same as economics.

      • ‘stealth66’ said “The rest of the World has no issues with turboprops.”


        Turbofan airliners fly the world for airlines not based in the US.

        Perhaps you mistake frontiers for big cities. Northern Canada has many turboprop services because demand is low and to significant extent they can use shorter runways. But for long distances, like YEG-YRB, the 737 is king. Dozens of twin otters service small resorts on the coast of the Maldives, but the country is building more big airports to jet tourists into the country.

        You sound like you have an anti-American bias that overcomes epistemology.

        Harry Binswangers book ‘How We Know’ is recommended for people who want to get things right.

        • Seriously, dude?

          I was talking about the American (as in USA) irrational aversion to turboprops. But thanks for pointing out that Canada isn’t America.

          There’s zero anti-american bias, so maybe take your own advice?

          • “I was talking about the American (as in USA) irrational aversion to turboprops. But thanks for pointing out that Canada isn’t America.”

            Precision is good in aviation communication.

            Last I heard, Alaska was ‘American’, many turboprops there but also turbofan airliners.

            One place turboprops were better than 737s was Dutch Harbour, tricky airport to fly into with winds and a late turn onto final. scraping tip or pod is not a good thing, both happened. Need slow, extra responsive on controls and thrust (single shaft engines like the Electra’s were good.

    • People don’t like cramped aircraft with non-reclining seats and no amenities either, but Ryan Air ¯\_(ツ)_/¯

      If an open rotor aircraft has 20% better fuel burn AND avoids carbon landing fees the saving will be enough to get passengers on board.

  3. The bypass ratio increases more than the rotor disk diameter as the air just outside the fan is accelerated as well. Containment is an issue but I assume those fans will be life limited and rotate pretty slow. Might be a good engine for a A400M-neo.
    I think CFMI will investigate how to best use the LH2 cooling capability in the core engine and that will take time. You don’t want to design 2 new core engines all the way to certification and be delayed with unknown certification requirements on new cooling schemes. Still with EU money you can design and test 2 different core engines for the same LP system. Being able to use LH2 cooling in the Fan reduction gear, HPC stators, HPT Nozzle Guide Vanes, HPT Active clearance control system and bearing compartments gives performance benefits as the heated LH2 then goes into the burners that can be shorter than todays combustion chambers and thus make the engine lighter and stiffer.

  4. Contrary to the impression given by the convivial photos at the G7 summit last weekend, the US and EU still disagree strongly on the subject of trade with China. The EU is sick to the teeth of having its trade with other countries impeded by an ever-growing list of “de facto” US export barriers (Iran is a case in point). At this rate, JVs such as that between GE and Safran are at risk of hitting a dead end — there may not be any CFM left to bring this project to fruition.
    It seems that many of the world’s blocks have realized that they have surrendered autonomy to an unacceptable extent in favor of globalization. Lots of disentanglement on the horizon — energy, semiconductors, rare earth metals…and aviation.

  5. Both GE and Pratt were researching independently on the Unducted Fan (UDF) concept from the 80s. GE teamed up with NASA on their demonstrator GE36 mounted on the 7J7.

    Well, Pratt decided to go the way of the GTF instead.

    Apparently, there was a stretched and un-stretched of the 7J7, with only the latter un-stretched version powered by the GE36.

    The name RISE reminds me of this song (All Rise by UK boy band Blue,, for those who remember.

    The verdict will out on GTF versus UDF. We will “rest our case” when RISE comes out.

  6. Noise at takeoff may be the most difficult issue to solve. If this can get solved with a closely integrated fuselage design, I do not see any issue to realize this concept.

  7. On the subject of hydrogen in aviation:
    (not off-topic, since the RISE press release mentions hydrogen)

    “Airbus to develop hydrogen fuel tanks for aircraft at new development centres”

    “Airbus has setup development centres at its sites in Bremen, Germany and Nantes, France to develop hydrogen fuel tanks for its future aircraft, and scheduled the first flight tests of the new fuel systems for 2025.

    The Zero-Emission Development Centres (ZEDC) aim to develop Airbus’ capability to manufacture the cryogenic hydrogen fuel tanks that will be required for future hydrogen-fueled aircraft. The centres will also look at the design and integration of the tanks into aircraft.
    brought to you by Element Aerospace

    The technology developments will cover the full product and industrial capabilities from elementary parts, assembly, systems integration and the cryogenic testing of the final liquid hydrogen tank system.

    Both ZEDCs will be fully operational by 2023 to build liquid hydrogen fuel tanks with a first flight test scheduled for 2025.”

    • Saw report that Rolls Royce said no to H2 -sometime after 2050

  8. Technically this project is far from the Unducted Fan (UDF) tests in the eighties, which sported 2 counter rotating unducted fans. This is basically a single fan & vanes to turn the un-swirl wake from the fan. Technically much simpler and probably less noisy (no shock waves from the blade tips hitting each other).

    Essentially it’s more a big turbo prop like TP400, than a turbofan..

    • Big question is none of the air flow and props are new.

      So they dropped the 2nd set of blades due to complexity. But those were there for a reason of efficiency needed to compete with a full on install of a pylon mounted jet.

      And if its so slam dunk, why has this not been done before and avoid the Turbo Prop gear box aspect?

      They have been working with advanced blades since WWII and the final determination was that there was nothing you could do to compete with a jet engine.

      • The time is getting right for high power high efficiency power gearboxes, now on the PW1100G, soon on the RR Ultrafan and this one for CFMI. Another development are 3D woven fanblades and the CFD tools making possible to get both low noice and high efficiency at high cruising speeds/T-O. So the progress makes it possible today. Now the CO2 issue are pressing for higher efficiency that mainly is bypass ratio and compressor exit pressure. We will see if there will be one new core engine optimized for SAF fuel or two with the other optimized for LH2.

  9. read in aviation week that they are claiming a 27% reduction in fuel burn vs CFM56-7B.

    the Leap engine for the 737 is already 14% better than the -7B and the GTF another 3% or so better than that.

    so we are talking maybe 10% improvement vs the current baseline? that just barely gets you into “re-engine a current design is looking attractive” levels of improvement, and nowhere near “design a whole new airplane” levels.

    • Thank you, I did not have the latest Av week but that ratio has stayed the same pretty much all along.

      And that is fuel burn alone, not the overall package of install.

    • I believe the Otto Aviation Celera 500 is the most innovative aircraft in terms of efficiency today by far. The fuselage is a classic egg shaped ‘laminar flow’ type with a reflexed tuna fish tail for pressure recovery with a cross sectional profile like the ‘laminar flow’ wing on a P-51 Mustang.

      Because of the Celestra fuselage has the surface smoothness of composite skinning and because of suction of the pusher prop will provide laminar flow control of the tail section (where laminarity normally breaks down) the reduction in drag is significant.

      It strikes me that a propfan would ideally be placed in the tail of the aircraft.

      Twin engines with individual drive to a coaxial counter rotating prop might even get some kind of ETOPS rating. If not then podded engines under the wings could do this and this kind of ‘trimotor’ would be free of ETOPS restrictions.

  10. Will a smaller diameter reduce noise emissions by reducing the whipcrack-sound produced when the blade tips go supersonic and form shock waves?

    • no. in fact smaller diameter requires faster rotation to achieve equivalent thrust. the blade tips will be supersonic and they will be interacting sonically with the open stators.

      however, increased fundamental understanding of how the noise is generated, how to mitigate it and modern design and sim tools should make it possible to greatly reduce the amount of noise produced vs previous designs.

      things like blade shaping, using different prime numbers of blades and non uniform spacing of stators can set up self cancelling sound patterns in certain regimes, but you are just not going to get as quiet as you could if you combined that with a nacelle. it will never get to GTF levels of quiet.

  11. Presumably swirl vane development at CFM has now advanced to a point where the thrust and efficiency gain is sufficiently close to theoretical max. So from that point of view seems like a good idea to simplify things.

    But how is cruise affected by the switch to only one rotating fan?

    Also, am guessing this significantly & reliably helps address the vibration issues (causing shortened component life, noise, whatnot) of the 80s designs.

    As for hydrogen compatibility, seems a no brainer really, assuming it doesn’t affect SAF fuelled efficiency/reliability/maintainability/cost?

    • As Bjorn pointed out it is more than hydrogen compatibility. Hydrogen allows for increase in efficiencies in a number of ways:
      * cooling of turbine blades
      * cooling of the compressed air
      * use of superconducting materials in generator/starters/boosters

      My prediction is while there may be a simple “compatible” version there will also be a dedicated hydrogen core that takes advantage of those opportunities.

      • Efficiency gains from pre and intercooling may be a key advantage of cryogenic hydrogen engine but to what degree will the hydrogen version of the RISE engine use cryogenic precooling & intercooling?

        I have been tracking PtL (Power to Liquids) carbon neutral fuel development back to 1990, it actually has a long history going back to the 1970s if not earlier. We can say that for direct air capture of CO2 the upper limit of practical efficiency is probably 60% and that for CO2 capture from concentrated ‘unavoidable’ sources such as cement or aluminium production its 65%. That’s based on reasonable assumptions and experimental work.

        If one built a plant right now direct air capture would be about 45% efficient.

        Cryogenic hydrogen production via electrolysis (using the same level of technology) would struggle to reach 60% but it looks likely that the whole process from electrolysis to liquefaction could one day achieve 80%.

        So its reasonable to say that cryogenic hydrogen will probably only require 75% as much energy as PtL. The recovery of energy for the hydrogen engine looks more efficient though.

        However cryogenic hydrogen is more difficult to handle and efficiency is not as important as cost. It may be cheaper to to produce and transport PtL from remote regions of the world than hydrogen. We don’t know.

        I sense that hydrogen will not be as big in air transport as Airbus is suggesting. Hydrogen will be big in industrial process, a part of land transport, domestic and commercial.

  12. > engines to enter service around the mid-2030s.

    If you believe in perfidious Europe you can see this announcement as a well played card in the “air wars”. How can Boeing develop one much less two new aircraft for entry into service before the mid 2030’s knowing an engine with 20% better fuel burn is coming? One that can’t be retrofitted to an airframe optimized for a turbo-fan. Even the tie up with GE is brilliant, prevents US gov from calling any subsidy an unfair subsidy of a EU company.

    And of course the timeframe is perfect for Airbus.

    • No addressed is the specific engine mounting involved.

      Boeing has made that work with the CFM alliance but Airbus has gone with two engines on the A320.

      The mounting package is so specific and putting it on the wing looks to be a huge stretch for so called open rotor (makes it a Turbo Prop with no gear box ?)

      So someone has to design a specif wing at least as rear structure adds cost that negates its fuel advantage (assuming there is one over an updated GTF)

      I thought at one time open rotor was very possible but it keeps bumping 10 years down the road.

  13. “But if Alaska Airlines has a problem with a Turbo Prop between the two largest Alaskan Cities (small) …”

    Um, what?

    Anchorage and Fairbanks are a ways apart, and want fast service to the lower 48 states. Similarly with Juneau, the state capitol which is not reachable by road. And it is a hike from Fairbanks to Barrow. And a hike to the settlement near Russia, I don’t know what flies there as I have brain fade on the name – the place where caribou disappeared over a century ago.

    • Anchorage Fairbanks is 350 air miles (more or less). Solidly inside the Turbo Prop sweet spot.

      AK replaced the Dash 8 (and I do like that airplane) with the E(175 I think)

      Anchorage – Juneau is a bit on the far side of the Turbo Prop sweet spot (750 Miles?) Only TP flying there is FedEx and the ATR freight ops (nothing in between it and their 757s)

      Fairbanks Prudhoe (Barrow is not very big, the Oil Patch is) is 350 miles but a lot of the flights are a contract 737.

      As far as I know the Caribou are still out in Western AK, Nome being the closest to Russian on Land (Little Diamede closest period). Herds rise and fall but none gone as far as I know.

      • TW, fact-check:

        Over a century ago people in the area of Nome AK were in trouble for food because caribou had disappeared, at a time when salmon population was low and there were few whales nearby.

        Some people helped them by arranging for reindeer to be herded from Russia.

        Long afterward the original caribou strains returned.

        Then there was a bureaucratic problem, obsessive laws treat the sources of caribou differently, yet they mingled, the tribal people had no need to differentiate, reindeer=caribou, and caribou don’t know about such legal foolery. Bureaucrats have cost locals much work.

        (Caribou do move, several years ago a herd of tundra caribou in northern Canada disappeared. Tribal elders tried to tell eco-flappers like David Suzuki where to look, eventually someone got off their duff and there they were – where they’d been before.
        Otherwise caribou shift locally, some of the only herd in Canada with declining population probably moved to that furrin land next door where herd population has increased. Ilegal immigrants?)

        Today we have airplanes to quickly transport aid to people or carry them out of harm’s way, yet a certain mentality attacks productive aviation using false claims about runaway climate warming that is not and cannot happen.

        As for flying to Nome, only 4000 people but it is waaay out there near Russia. Only local roads. Make sure navigation good, Nome is on the Seward Peninsula but there is a city named Seward in southeast AK.

        • Actually, I spoke of tundra caribou. Herds of forest caribou are declining, they are smaller (probably because food is not as plentiful/rich). Lifestyle/environment are not sustainable.

      • Sigh.

        The story of reindeer brought to the Seward Peninsula of Alaska is known: REF identifies the movement of ‘reindeer’ from Russia to Alaska in 1891, it omits that salmon populations were down at that time.

        (Not to be confused – hah! – with the settlement of Seward in SE AK. Nome is the main settlement on the Seward Peninsula today.)

        Beware that some maps mis-represent populations by omitting ‘semi-domesticated’ herds they call ‘reindeer’, only showing what they call ‘caribou’ – same species (tundra sub-species in both cases).

        Huge problem for Inuit on the Peninsula is that when the original caribou came back they and the semi-domesticated ones mixed, and some of the latter migrate east with descendants of the original caribou.

        Some local Inuit are able to reduce losses by feeding the ‘reindeer’ goodies and keeping them corralled part of the year, I presume including in rutting season. Otherwise they leave them on the range much of the year as done with cattle to the south, chasing them back to corrals for harvesting, neutering, and innoculations. As for convincimg gummint bureaucrats which animals are from which origin, they do use tags, and perhaps now using basic DNA screening – but the proper solution is for eco-goons to get out of their way. (A ‘wee problem’ is the two origins interbreed, naturally.)

        Interesting story of a helicopter pilot who risks herding them from the air, he is a descendant of the herders who came from Russia with ‘reindeer’. He says pilots need cowboy smarts, claims easier to teach a cowboy flying skills than a pilot cowboy skills.

  14. Elsewhere in the unshrouded propulsor world, an interesting little charter flying service.

    All props, including a Bellanca Scout for scouting – good visibility, slow, …

    In the news because they were chartered by a pair of clever stupid’s who flew from Vancouver BC to Whitehorse, then violated quarantine to fly several hundred miles to a small tribal settlement where a visiting mobile clinic was vaccinating all resident comers. Exposed because while claiming to be working temporarily at a nearby motel they tried to mooch a ride the 2 miles back to the airport. They had booked vaccination in advance, lying all the way including to the flying service and the local airport.

    (Just broadening the education and perspective of people in this forum. 😉

    [A lesson pertinent to all the PR about electric aircraft startups, noting the failure of one of the electric truck startups that was exposed as dishonest (NOT Lordstown that is also failing financially). Among the other one’s capers was filming a supposed prototype rolling downhill, labelled hydrogen but actually using CNG.

    Bjorn, beware of hype.]

  15. Not pushing the edge I suppose, given decades of turboprops with fatal results of blade failure.

    Such as a C-130 sliced apart by a blade that escaped because of corrosion missed in overhaul inspection. Blade went through top of fuselage on its way across the airplane, fuselage broke up.

    Of course shrouded fan blades have hurt airliners recently. Airframe designers are increasingly providing resiliency such as by routing cables and wiring separately for parallel redundant systems. And perhaps

    Direct shielding is heavy, prop airliners like the DC3 had padding on outside of fuselage to reduce damage and noise from ice coming off of prop blades. Preferably keeping cockpit out of line of blades (the Basler turboprop conversion lengthened forward fuselage for balance so achieved that).

    Rigor is of course needed, this reminds me of Boeing MCAS fiasco:
    “slammed the company for proceeding with the launch “based on ‘impressions’ and ‘assumptions,’ rather than procedural checks and positive affirmations.”

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