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The potentially revolutionary Celera 500L aircraft

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Re: The potentially revolutionary Celera 500L aircraft

#111

Post by aidenn0 »

desdiv wrote: post #100
qzw wrote: post #58

Earlier quoted context omitted.

Definitely some extraodinary claims that will require extraordinary evidence to prove. Especially getting 20+ mpg for 4500 miles, while flying at 450mph, which is near the top end of what piston/propeller aircraft are capable of. For reference, the P51 (one of the fastest fighters of WWII) had a comparable top speed. The Piaggio Avanti [0] has a somewhat similar design and top speed (460 high speed cruise), but has t…

>Especially getting 20+ mpg for 4500 miles, while flying at 450mph That's not what they're claiming though. They're claiming that: 1. 20+ mpg 2. maximum speed of 450 mph 3. range of 4500 miles are possible individually, not that 1+2+3 are possible all at the same time.

TFA did not say maximum speed 450mph, it said "maximum cruising speed of at least 450mph" Still doesn't mean it gets 18-25mpg at 450.

If it can realistically do half of 4500 miles at 450mph, there are a lot of interesting routes (Gets you as far as Tel-Aviv from London, Boston to Phoenix, or Los Angeles to Miami).

Using that completely-pulled-out-of-my-ass number of half the range at 450, and assuming quadratic drag, the full range would be at about 300mph, so a roughly 12 hour flight from New York to London at a cost of $5k.

Re: The potentially revolutionary Celera 500L aircraft

#112

Post by rossjudson »

dmix wrote: post #102
karlkatzke wrote: post #80

Earlier quoted context omitted.

3300 feet in balanced density conditions. You’d better not bet on 3300 feet in Phoenix during the day time most of the year. Or Denver for that matter.

Sorry for the amateur question, but why does it take longer to take off in hot places? Doesn’t heat generate lift, like in gliders crossing hilly terrain? Or is it the heat offsetting with the cooler ground that helps, so you’d need a greater amount in hot places?

The term you're looking for is "density altitude".

Re: The potentially revolutionary Celera 500L aircraft

#113

Post by snovv_crash »

brunooo wrote: post #101
Retric wrote: post #89

Earlier quoted context omitted.

The Piaggio II ( https://www.aircraftcompare.com/aircraft/piaggio-p180-avanti... ) is missing several modern aerodynamic and efficiency features like winglets and gets 15MPG and has a 1600 Mile range. Significantly beating it’s fuel efficiency at similar speeds seems reasonable just eyeballing the two designs. Getting the full 20MPG at 450MPH might be a stretch, but it’s not all that unreasonable. Also, higher aerody…

I’m not sure those mpg numbers are correct: the more fuel efficient Piaggio EVO update, with winglets etc, in the extended range version can hold about 450 gallons of Jet A and has a 1770nm range, so even with plenty of reserves that doesn’t get it anywhere above half of 15mpg (from what I can find IFR reserve comes out to 75 gallons, thus 4.72mpg nautical or 5.4 statute). Which is why the jump in efficiency would be…

Turboprops are less fuel efficient, they just have a higher power to weight ratio than piston engines.

Re: The potentially revolutionary Celera 500L aircraft

#114

Post by jacobwilliamroy »

romski wrote: post #35
jacobwilliamroy wrote: post #33

Earlier quoted context omitted.

Commercial airlines have a future? In the near future, only the wealthiest people will be able to fly, and good luck denying them windows. As for everyone else, Im thinking theyre taking the windows out because they are planning to convert over to cargo flights or something.

You can fly right now if you want to - flights are very cheap! What point are you trying to make?

You can buy a cheap ticket on an empty plane. Do the math. This is a passing thing, and airlines are either going to raise prices or go out of business.

Re: The potentially revolutionary Celera 500L aircraft

#115

Post by KMag »

generatorguy wrote: post #108
dmix wrote: post #102

Earlier quoted context omitted.

Sorry for the amateur question, but why does it take longer to take off in hot places? Doesn’t heat generate lift, like in gliders crossing hilly terrain? Or is it the heat offsetting with the cooler ground that helps, so you’d need a greater amount in hot places?

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 Carnot efficiency does drop as T_c increases, so all else being equal, for the same amount of fuel being burned, you'll get less energy. However, more importantly, at higher temperatures, a given volume of air at the same pressure contains less oxygen. All else being equal, at higher ambient temperatures, you're burning less fuel. For a turbocharged engine, you could increase boost to counter-act the reduced density, but that increases both mechanical and thermal stresses within the engine.

Anyway, I think the reduction of oxygen density is the primary driver for reduction in power as ambient temperatures rise.

Re: The potentially revolutionary Celera 500L aircraft

#116

Post by sirk1882 »

karlkatzke wrote: post #81
baybal2 wrote: post #49

Earlier quoted context omitted.

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.

One engine, a turbocharged V-12.

And as others have mentioned, it's taken advantage of newer technology that allows six of pistons to be turned off.

The engine basically sounds like two in-line six cylinder engines that share many common single engine features but with the ability to shut off one side and use power from the remaining side.

So hypothetically, you fly up to altitude and climb using all 12 cylinders, then cruise on six.

That could be where the fuel efficiency is being notched up versus burning all 12 cylinders at all times.

Kinda like how people are still amazed variable displacement engines took them from 10mpg to 18-20mpg. It's also likely the engine has a number of other more recent innovations included too. Variable valve timing, etc, etc. A lot of new rather exciting new engine technology has come out in the last 20 years.

It's much like when we went from naturally aspirated aka carbs to electronic fuel injection/ignition.

Re: The potentially revolutionary Celera 500L aircraft

#117

Post by KMag »

Stevvo wrote: post #37
gregschlom wrote: post #27

Earlier quoted context omitted.

Ok, but so what? Is there something bad about diesel engines?

Not at all, without question it's a superior fuel to leaded avgas.

It has higher energy density, higher flash point (less prone to fire or explosion), less volatile (doesn't evaporate as quickly), and less toxic.

However, it's difficult to make a diesel that gets as much power/weight or power/volume as a comparable petrol engine.

There are trade-offs. It's not a universally superior fuel.

Re: The potentially revolutionary Celera 500L aircraft

#118

Post by jacobwilliamroy »

smabie wrote: post #42
jacobwilliamroy wrote: post #33

Earlier quoted context omitted.

Commercial airlines have a future? In the near future, only the wealthiest people will be able to fly, and good luck denying them windows. As for everyone else, Im thinking theyre taking the windows out because they are planning to convert over to cargo flights or something.

Why do you think that?

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 fracking, the U.S. army expected peak oil to happen sometime around 2015. Keep in mind, fracking is less efficient than old methods of oil extraction, and produces fewer barrels for the same amount of energy, and the energy for that extraction process comes from... oil. So we're burning the house down from both ends. Airlines don't stand a chance, in their current form.

Re: The potentially revolutionary Celera 500L aircraft

#119

Post by scarier »

thunderbird120 wrote: post #99
scarier wrote: post #86

Earlier quoted context omitted.

All of that helps, but a pilot flying an unpressurized experimental can still get up to 17.5k' VFR on oxygen. Assuming the Celera cruises around FL250, you're talking the difference between ~300KTAS and ~350 KTAS at 200 KIAS. I'd be shocked if they cruise much above FL300, regardless of how high their service ceiling proves to be--for anything other than a really long-distance flight, they'll spend too much time clim…

Their patent application implies that it is optimized for cruising at 50,000 feet. [1] https://patentimages.storage.googleapis.com/3b/f3/9a/928c862...

I mean, their patent application also claims an SFC of ~30-42 MPG at 460-510 mph...

A design cruising altitude of FL500 implies that they're seeing nearly all of their efficiency improvements due to the thin air at altitude (flying around 200 mph indicated, which isn't totally unreasonable for 20 mpg in a small-ish piston-prop), but I doubt they have the climb rate to actually reach that altitude in anything short of a transcontinental flight.

I like to think they crunched the performance numbers once or twice, but if they're off by the same amount they were with their initial SFC calculations, there's no way they'll reach an acceptable cruising altitude during an average flight.

Re: The potentially revolutionary Celera 500L aircraft

#120

Post by sirk1882 »

Someone1234 wrote: post #44
mortenjorck wrote: post #21

Earlier quoted context omitted.

Wow, this is a literal nightmare for flight anxiety sufferers.

Only if they don't replace them with even larger digital "windows." There's also been work towards electronic windows in aircraft.

Yeah but it'd be cooler if the sides were completely digital "windows".

What should these be called? Dindows? Digidows? Digdows?

I live in the arctic and I was thinking of building a home without windows but with same idea. It allows you to remove convective heat loss from windows almost entirely. Not to mention it's much cheaper than shipping up glass windows.

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