6 ms·

Definitely some extraodinary claims that will require extraordinary evidence to prove. Especially getting 20+ mpg for 4500 miles, while flying at 450mph, which

by qzw 6y ago

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 twin turboprops and a far shorter range and far lower claimed mpg. [0] https://en.wikipedia.org/wiki/Piaggio_P.180_Avanti https://en.wikipedia.org/wiki/Piaggio_P.180_Avanti

Retric 6y ago
The Piaggio II (https://www.aircraftcompare.com/aircraft/piaggio-p180-avanti-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 aerodynamic efficiency means lower HP requirements. Moving that weight savings to fuel can boost range even further. PS: Winglets are actually really old technology. It’s making the trade offs worth it including significantly increased weight at the wing tip that’s new.
- brunooo 6y ago
  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 so extraordinary.
  - snovv_crash 6y ago
    Turboprops are less fuel efficient, they just have a higher power to weight ratio than piston engines.
  - sunstone 6y ago
    I recall from the last time this plane hit the news cycle that it is designed to cruise at 60,000 feet where air density is lower and better fuel efficiency can be had.
    - VBprogrammer 6y ago
      To put that claim into context the manned single engine piston height record is held by a specially modified Rutan Long Ez and was around 35,000ft.
    - mediaman 6y ago
      Prop planes don’t work well at higher elevation. There’s nothing for the prop to work against. It’s why jet engines, with their compression, work better. Props work better than jets at low elevation where the span of a propeller can work against a lot of high density air.
nl 6y ago
Much of the improved efficiency comes from the engine[1], which claims "50% lower fuel burn compared to turbine engines in the same power category". The engine company is German and so we can make lots of jokes about German companies' fuel efficiency claims I guess. Nevertheless, it has been around since 2012 and is used in a few planes already, so presumably there is some measurable improvement there or they'd have taken the claim down by now? For comparison, this engine has a Specific fuel consumption of 210 g/kW/h, while a P&W PT6A-6 (older, slightly more powerful: 431 kW vs 368kW) has 0.408 kg/kW/hr[2] [1] https://red-aircraft.com/?lang=en https://red-aircraft.com/?lang=en [2] http://www.all-aero.com/index.php/contactus/64-engines-power/13099-pratt-whitney-canada-pt6 http://www.all-aero.com/index.php/contactus/64-engines-power...
- scarier 6y ago
  Still, a plane with half the aerodynamic drag and twice the BSFC is only getting 4x the fuel efficiency, not the ~10x they're claiming. Even if they're making a bit of "free" thrust from their cooling system (which has been a thing since WWII), I don't see what accounts for the rest, even ignoring that the Celera likely has a significant increase in frontal area due to the standing-height cabin.
  - brunooo 6y ago
    Re “free thrust/WWII”: Real Engineering recently did a great summary of the P47 Thunderbolt intercooler and general craziness of the engine at https://youtu.be/IwqTN5fhMR8 https://youtu.be/IwqTN5fhMR8
  - nl 6y ago
    They are claiming slightly under 10x fuel efficiency compared to a jet (2-3 mpg vs 18-25 mpg). That doesn't seem completely unreasonable. A Pilatus PC-12 (which is the turoprop competition here) NXG gets around 4.3 mpg.
desdiv 6y ago
>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.
- aidenn0 6y ago
  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.
  - qzw 6y ago
    $5k plus pilots (I’d want two for a transatlantic flight). And you’d still be stuck inside a very small space for 12 hours, with what’s likely to be a porta-potty level lavatory and minimalist galley. Oh, and a single piston engine, which is less reliable than turbines, over a lot of very cold water. Not sure that would be the best use case for this plane.
    - anovikov 6y ago
      Well, the size of aircraft certainly allows for fully enclosed, proper lavatory. CJ3 used for size comparison, has one.
    - kristopolous 6y ago
      Everything deserves to have a Version 1.0 I have high hopes for the future efforts
    - dzhiurgis 6y ago
      Plus airports, airspace, immigration, depreciation, insurance. So more like 20k.
VBprogrammer 6y ago
I'm calling bullshit. Compare it to the TBM900 which has a 900hp turbine engine and vastly similar layout. There is no way they can go 60 knots faster on 300 less horse power. And even if they somehow pull off that trick, that short skinny wing will make the MU-2 feel like a safe family minivan.
- asdfadsfgfdda 6y ago
  The layout/payload may be similar to a TBM, but I'm guessing the wing loading and cruise altitude will be higher. So it's definitely feasible to go faster on less power.
  - VBprogrammer 6y ago
    Aerodynamic drag is a square relation so the difference in drag there is about 40%. With 65% of the power. I think occam's razor applies here. Either the aerodynamics of reasonably modern aircraft designs leave a huge amount on the table or this startup is telling fibs. There are other reasons to be suspicious, modern diesel engines rely on a large amount of turbo charging to achieve sea level rated power, it's difficult to believe they are able to maintain this rated power to 50,000ft or 60,000ft. (In the case of the TBM the engine is actually capable of about 1300hp at sea level but is "flat rated" to what it can maintain at altitude). Finally, almost all high altitude aircraft have long wings (think the U2 as that is not far from what we are talking about here). Adding longer wings typically increases high altitude performance (there are aircraft with model variants where the wings got longer, like the twin commander). This aircraft appears to have borrowed a couple of surfboards.
    - Tuna-Fish 6y ago
      > I think occam's razor applies here. Either the aerodynamics of reasonably modern aircraft designs leave a huge amount on the table or this startup is telling fibs. Aerodynamics of reasonably modern aircraft designs do leave a huge amount on the table. Generally for good reasons, though. The 500L is clearly almost entirely a laminar-flow design, unlike conventional aircraft (including the one you linked). Experience from gliders have shown that a small laminar flow design like this can have less than a third of the drag of what a conventionally shaped design of roughly similar size. There are two major downsides to designing like this: Firstly, the shape is entirely determined by physics, leaving very little wiggle room for manufacturing or practical concerns. Without modern composites, cost-effectively manufacturing the frame is impractical. Secondly, the great drag properties are very dependent on the properties of the skin of the aircraft. Laminar-flow gliders can have their glide ratios halved after accumulating a few too many insects on the leading edge. If you want to fly very high, (as this plane seems to want to), better hope you have an amazing de-icing system, or even a very small amount of ice will trash your aerodynamics.
sgt101 6y ago
I think that the evidence can be really simple (not extraordinary) - just gas it up, fly it for 4500miles in about 11hrs.
aliswe 6y ago
Just a nitpick, extraordinary claims normally do not require extraordinary evidence. For example, to gather evidence that, for example, there is a man who could run for 50mph in short bursts, it would require nothing but ordinary evidence. Have a nice day!

by qzw 6y ago

Retric 6y ago

The Piaggio II (https://www.aircraftcompare.com/aircraft/piaggio-p180-avanti-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 aerodynamic efficiency means lower HP requirements. Moving that weight savings to fuel can boost range even further. PS: Winglets are actually really old technology. It’s making the trade offs worth it including significantly increased weight at the wing tip that’s new.

brunooo 6y ago
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 so extraordinary.
- snovv_crash 6y ago
  Turboprops are less fuel efficient, they just have a higher power to weight ratio than piston engines.
- sunstone 6y ago
  I recall from the last time this plane hit the news cycle that it is designed to cruise at 60,000 feet where air density is lower and better fuel efficiency can be had.
  - VBprogrammer 6y ago
    To put that claim into context the manned single engine piston height record is held by a specially modified Rutan Long Ez and was around 35,000ft.
  - mediaman 6y ago
    Prop planes don’t work well at higher elevation. There’s nothing for the prop to work against. It’s why jet engines, with their compression, work better. Props work better than jets at low elevation where the span of a propeller can work against a lot of high density air.

nl 6y ago

Much of the improved efficiency comes from the engine[1], which claims "50% lower fuel burn compared to turbine engines in the same power category". The engine company is German and so we can make lots of jokes about German companies' fuel efficiency claims I guess. Nevertheless, it has been around since 2012 and is used in a few planes already, so presumably there is some measurable improvement there or they'd have taken the claim down by now? For comparison, this engine has a Specific fuel consumption of 210 g/kW/h, while a P&W PT6A-6 (older, slightly more powerful: 431 kW vs 368kW) has 0.408 kg/kW/hr[2] [1] https://red-aircraft.com/?lang=en https://red-aircraft.com/?lang=en [2] http://www.all-aero.com/index.php/contactus/64-engines-power/13099-pratt-whitney-canada-pt6 http://www.all-aero.com/index.php/contactus/64-engines-power...

scarier 6y ago
Still, a plane with half the aerodynamic drag and twice the BSFC is only getting 4x the fuel efficiency, not the ~10x they're claiming. Even if they're making a bit of "free" thrust from their cooling system (which has been a thing since WWII), I don't see what accounts for the rest, even ignoring that the Celera likely has a significant increase in frontal area due to the standing-height cabin.
- brunooo 6y ago
  Re “free thrust/WWII”: Real Engineering recently did a great summary of the P47 Thunderbolt intercooler and general craziness of the engine at https://youtu.be/IwqTN5fhMR8 https://youtu.be/IwqTN5fhMR8
- nl 6y ago
  They are claiming slightly under 10x fuel efficiency compared to a jet (2-3 mpg vs 18-25 mpg). That doesn't seem completely unreasonable. A Pilatus PC-12 (which is the turoprop competition here) NXG gets around 4.3 mpg.

desdiv 6y ago

>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.

aidenn0 6y ago
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.
- qzw 6y ago
  $5k plus pilots (I’d want two for a transatlantic flight). And you’d still be stuck inside a very small space for 12 hours, with what’s likely to be a porta-potty level lavatory and minimalist galley. Oh, and a single piston engine, which is less reliable than turbines, over a lot of very cold water. Not sure that would be the best use case for this plane.
  - anovikov 6y ago
    Well, the size of aircraft certainly allows for fully enclosed, proper lavatory. CJ3 used for size comparison, has one.
  - kristopolous 6y ago
    Everything deserves to have a Version 1.0 I have high hopes for the future efforts
  - dzhiurgis 6y ago
    Plus airports, airspace, immigration, depreciation, insurance. So more like 20k.

VBprogrammer 6y ago

I'm calling bullshit. Compare it to the TBM900 which has a 900hp turbine engine and vastly similar layout. There is no way they can go 60 knots faster on 300 less horse power. And even if they somehow pull off that trick, that short skinny wing will make the MU-2 feel like a safe family minivan.

asdfadsfgfdda 6y ago
The layout/payload may be similar to a TBM, but I'm guessing the wing loading and cruise altitude will be higher. So it's definitely feasible to go faster on less power.
- VBprogrammer 6y ago
  Aerodynamic drag is a square relation so the difference in drag there is about 40%. With 65% of the power. I think occam's razor applies here. Either the aerodynamics of reasonably modern aircraft designs leave a huge amount on the table or this startup is telling fibs. There are other reasons to be suspicious, modern diesel engines rely on a large amount of turbo charging to achieve sea level rated power, it's difficult to believe they are able to maintain this rated power to 50,000ft or 60,000ft. (In the case of the TBM the engine is actually capable of about 1300hp at sea level but is "flat rated" to what it can maintain at altitude). Finally, almost all high altitude aircraft have long wings (think the U2 as that is not far from what we are talking about here). Adding longer wings typically increases high altitude performance (there are aircraft with model variants where the wings got longer, like the twin commander). This aircraft appears to have borrowed a couple of surfboards.
  - Tuna-Fish 6y ago
    > I think occam's razor applies here. Either the aerodynamics of reasonably modern aircraft designs leave a huge amount on the table or this startup is telling fibs. Aerodynamics of reasonably modern aircraft designs do leave a huge amount on the table. Generally for good reasons, though. The 500L is clearly almost entirely a laminar-flow design, unlike conventional aircraft (including the one you linked). Experience from gliders have shown that a small laminar flow design like this can have less than a third of the drag of what a conventionally shaped design of roughly similar size. There are two major downsides to designing like this: Firstly, the shape is entirely determined by physics, leaving very little wiggle room for manufacturing or practical concerns. Without modern composites, cost-effectively manufacturing the frame is impractical. Secondly, the great drag properties are very dependent on the properties of the skin of the aircraft. Laminar-flow gliders can have their glide ratios halved after accumulating a few too many insects on the leading edge. If you want to fly very high, (as this plane seems to want to), better hope you have an amazing de-icing system, or even a very small amount of ice will trash your aerodynamics.

sgt101 6y ago

I think that the evidence can be really simple (not extraordinary) - just gas it up, fly it for 4500miles in about 11hrs.

aliswe 6y ago

Just a nitpick, extraordinary claims normally do not require extraordinary evidence. For example, to gather evidence that, for example, there is a man who could run for 50mph in short bursts, it would require nothing but ordinary evidence. Have a nice day!