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The potentially revolutionary Celera 500L aircraft

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Re: The potentially revolutionary Celera 500L aircraft

#161

Post by ppf »

sirk1882 wrote: post #123
jacobwilliamroy wrote: post #118

Earlier quoted context omitted.

Because COVID has completely rejiggered the economy. Airlines legally are not allowed to pack hundreds of people into a cramped cabin. They're selling fewer tickets at lower prices, and they were already losing money on poor passengers to begin with. Plus, the oil crash is still coming. Fracking has delayed it for a short time, and the covid lockdowns also have slowed consumption, but it is still inevitable. Before f…

Which is why companies like this are going to be doing what Musk is doing with Electric vehicles. Now, if they could make these for 2000-3000km flights and they ran on 250kWh to 350kWh electric they'd be what the future entails. Especially if they weren't piloted and were fully automated.

Removing your energy source (fossil fuel) and replacing with energy storage doesn't fix anything - where does the energy to fill that storage come from? In some hypothetical future where renewable energy is very cheap, it will still be more efficient to use that energy to produce liquid fuel for planes.

Re: The potentially revolutionary Celera 500L aircraft

#162

Post by rm445 »

With a supposedly 10x improvement in an important metric (fuel consumption, together with reasonable speed and carrying enough fuel for range), there must surely be a big idea driving the change. Something that stands out.

I can't quite follow what specifically makes this aircraft special. I mean, it's an odd shape, and it has a piston engine. But what's driving the huge improvements? Improvements in CFD software driving aerodynamic design? Automotive technology bringing engine efficiencies? Some trade-off of stability that has previously been avoided but new avionics have overcome? The comparisons are all against business jets - is it in some way a well-designed propeller aircraft sitting in the space where the utility of jets versus propeller craft starts to cross over and small jets become inefficient?

I suppose it's not impossible that it sits in an unexplored area of the design space - a clever designer starting from a clean sheet of paper and ending up with something that works really well. But it would be extremely unusual after a century-plus of innovation. I don't like that breathless articles are written about this plane without any attempt to describe what the special sauce may be.

Re: The potentially revolutionary Celera 500L aircraft

#163

Post by redis_mlc »

I read this article threads, and once again HN comes up short on aviation knowledge. Here's some actual facts:

- Germany is always producing diesel piston-engine companies. The previous one was Thielert, which folded in 2008, and is now owned by China (Avic):

https://en.wikipedia.org/wiki/Thielert_Centurion

- diesel engines are popular ideas because most of the world doesn't have avgas available (including Africa, Far North, etc.)

- jet engines work most efficiently at high altitude (thermo equation), but pistons generally work best low density altitude. Pistons are generally twice as efficient as jet engines historically.

A key method of boosting power in WW2 was cooling combustion with combinations of water and alcohol, which is how they approached and exceeded 2000 HP.

- Scaled Composites made mostly military prototypes, so irrelevant for civil uses. Sold to Northrop Grumman in 2007.

https://en.wikipedia.org/wiki/Scaled_Composites

- regarding "jokes about German companies' fuel efficiency claims" - all auto makers fake efficiency and emissions results to get around government regulations, or blend results from one model with another to average it down. Volkswagen just got caught.

- regarding "planes for rich people", I doubt if this engine will be used outside charter operations, IOW for commercial revenue use, like a tractor. Boom will never see the light of day - it's just a vanity project for the designers.

Source: commercially-rated airplane pilot.

Re: The potentially revolutionary Celera 500L aircraft

#164

Post by cerebellum42 »

justinclift wrote: post #152
qzw wrote: post #129

Earlier quoted context omitted.

Sure, there are all kinds of trade offs between speed, range, useful load, altitude, burn rate, etc. But it’s really the combination of 450, 4500, and 20+ that would make this plane revolutionary . Otherwise it wouldn’t be all that interesting. And if we are to take seriously their claim of competing with commercial aviation, then it would really have to perform pretty close to all three of those numbers at the same…

Well, from London to New York is apparently about 3500 miles, and a 15 hour journey for that sounds reasonable.

A single engine plane is most likely not going to be used for ocean crossings regularly, for safety reasons, even if it is technically capable of it. Additionally, I'm not sure it has enough spare fuel reserves to make the trip with enough margin for error or unforeseen circumstances.

Re: The potentially revolutionary Celera 500L aircraft

#165

Post by richthegeek »

justinclift wrote: post #152
qzw wrote: post #129

Earlier quoted context omitted.

Sure, there are all kinds of trade offs between speed, range, useful load, altitude, burn rate, etc. But it’s really the combination of 450, 4500, and 20+ that would make this plane revolutionary . Otherwise it wouldn’t be all that interesting. And if we are to take seriously their claim of competing with commercial aviation, then it would really have to perform pretty close to all three of those numbers at the same…

Well, from London to New York is apparently about 3500 miles, and a 15 hour journey for that sounds reasonable.

Especially if you're saving time at either end by skipping all the Heathrow delays (long security checks, baggage check, etc)

Re: The potentially revolutionary Celera 500L aircraft

#166

Post by usrusr »

baybal2 wrote: post #49
Stevvo wrote: post #30

It seems a bit dishonest to compare it to a jet, when the obvious competition is a single engine Turboprop like a TBM or PC-12. On paper it beats those aircraft, but by a far less impressive margin when you consider engine TBO, which is currently 1250 hrs on the EASA cert. With the inherent unreliablilty of piston engines, a PT-6 might look more appealing. I'd love to see this aircraft come to market, but I fear it m…

Big guesstion, do they have one, or two engines? A combiner gearbox does not fare well in aviation, as history show. I have a hard time believing they can get to such speed with just 500hp.

That advertised speed seems to be ground speed, the trick is that they designed this thing to fly very high where the corresponding IAS is much lower. What's new (and a truly surprising as impressive technological achievement!) is that they do this on a piston engine which are notoriously less capable at high altitudes than jets or turboprops.

An implication of this is that short-haul applications will see neither the speed more the mileage advertised. I still want to see the general design principles applied to the problem of regional feeder flights, it won't be quite as over the top impressive but it would still be the closest to "slow steaming" available

(speed really doesn't matter on feeder connections where boarding alone takes longer than the flight, but it's very hard for aircraft to trade speed for efficiency once non-negligible payloads are involved)

Re: The potentially revolutionary Celera 500L aircraft

#167

Post by fluffything »

rm445 wrote: post #162

With a supposedly 10x improvement in an important metric (fuel consumption, together with reasonable speed and carrying enough fuel for range), there must surely be a big idea driving the change. Something that stands out. I can't quite follow what specifically makes this aircraft special. I mean, it's an odd shape, and it has a piston engine. But what's driving the huge improvements? Improvements in CFD software dri…

> had a maximum cruising speed of at least 450 miles per hour and a range of over 4,500 miles

Given the shape of the airplane, I'd guess the 4,500 miles range is not at 450 miles per hour, but much much less. Also, it needs to fly very high, so you need to correct the time it takes to travel with this with the longer take off and landing times.

It wouldn't surprise me if the "effective" velocity of this plane for long distances was more like 200 mph. I hope I'm wrong.

Re: The potentially revolutionary Celera 500L aircraft

#168

Post by cerebellum42 »

littlestymaar wrote: post #145
generatorguy wrote: post #108

Earlier quoted context omitted.

When it is hot out Air is less dense so the wings don’t generate as much lift. I believe engines make less power when the air in is hotter too as there is less delta T. Something something Carnot cycle

The engine indeed makes less power, but since the air density is lower, you also have much less drag. (I know that for cars, the drag reduction dominates the power efficiency). For airplanes take-off, the lift is the issue I'd say.

Yep it's lift and for some planes power loss due to less oxygen in the engine, but that highly depends on the kind of engine. You do get faster easier due to less drag but you also need to be faster until you have enough lift to take off. So maybe the takeoff run won't take that much longer, but you'll have covered a lot more distance.

Re: The potentially revolutionary Celera 500L aircraft

#169

Post by nabla9 »

The revolutionary part is to use V12 turbo-diesel piston engine for high cruise altitude instead of turboprop or jet engine.

Aerospace experts are skeptical https://www.thedailybeast.com/this-weird-plane-could-be-the-...

>Juan Alonso, a professor in the Department of Aeronautics at Stanford University, has his doubts. A 30 percent improvement in fuel-efficiency is possible in an airplane with a new, more aerodynamic wing design, an ultra-light airframe made from high-tech composite materials and a super-efficient engine.

>But an 800 percent improvement? “Unlikely,” Alonso told The Daily Beast. The Celera 500L’s rear-mounted propeller is a good choice for a more fuel-efficient plane, Alonso said. But the egg-like fuselage probably is less fuel-efficient than the narrower fuselages on planes such as the PC-12, he pointed out.

>Mark Drela, an MIT aeronautical engineer, is equally skeptical. “The 500L looks fairly well-designed,” Drela told The Daily Beast, “but I cannot say whether it’s close to optimum, or whether the diesel engine makes sense.”

> To say for sure, Drela said he’d need to know how much the Celera 500L weighs and how efficient its engine is. Since Otto isn’t talking, Drela can only guess. And he’s guessing that the Celera 500L isn’t nearly as efficient as Otto hopes it will be.

Re: The potentially revolutionary Celera 500L aircraft

#170

Post by VBprogrammer »

cerebellum42 wrote: post #164
justinclift wrote: post #152

Earlier quoted context omitted.

Well, from London to New York is apparently about 3500 miles, and a 15 hour journey for that sounds reasonable.

A single engine plane is most likely not going to be used for ocean crossings regularly, for safety reasons, even if it is technically capable of it. Additionally, I'm not sure it has enough spare fuel reserves to make the trip with enough margin for error or unforeseen circumstances.

Single engine aircraft with a range of around 800 miles are regularly ferried across the Atlantic. Now, I'm not for a minute suggesting that this is an everyday pleasure flight, it's something which takes planning, preparation and additional equipment. However, all I'm pointing out is that range would be the least of your problems if any of the claims prove true.

If you are interested this site gives a good overview of the routes and the legs involved http://220kts.com/ferry-flights/atlantic-ferry-routes.html

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