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Diesel power -- not just for locomotives and heavy trucks and container ships, anymore

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Diesel power -- not just for locomotives and heavy trucks and container ships, anymore
Posted by Paul Milenkovic on Friday, October 29, 2021 9:40 PM

From Air & Space Mag The Celera 500L Just May Revolutionize Business Aviation | airspacemag.com | Air & Space Magazine

"A cruise speed of 460 mph at 50,000 feet, with a range of 4,500 nautical miles. And, the company claims, it will be five times more cost-effective and eight times more fuel-efficient than bizjets with comparable performance, thanks to the super-smooth laminar flow surfaces, high-​aspect-ratio wings, and an innovative, lightweight V-12 diesel engine. It’s more efficient than other turboprops too."

Maybe that V-12 engine could power the next generation of diesel multiple unit (DMU) trains?

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?

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Posted by 7j43k on Friday, October 29, 2021 10:17 PM

You might have missed out on the Budd RDC's:  diesel.

 

 

Ed

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Posted by BaltACD on Friday, October 29, 2021 11:11 PM

Aren't Jets in fact a form of diesel - they compress air to the point that when fuel is injected it burns and creates thrust.

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Posted by SD70Dude on Saturday, October 30, 2021 12:08 AM

Diesel engines designed for airplanes have been around since at least the 1930s (see Junkers Jumo 205).

Rather than replacing jets or turboprops, a far bigger effect would be the drastic reduction in the use of gasoline piston engines in airplanes, which are now the last large user of leaded fuel.

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Posted by rdamon on Saturday, October 30, 2021 12:18 AM

General Aviation is starting to move to diesel power running JET-A as 100LL AVGAS is becoming hard to get outside of the US.

http://www.continental.aero/diesel/engines/cd300.aspx

 

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Posted by Paul Milenkovic on Saturday, October 30, 2021 7:02 AM

SD70Dude

Diesel engines designed for airplanes have been around since at least the 1930s (see Junkers Jumo 205).

Rather than replacing jets or turboprops, a far bigger effect would be the drastic reduction in the use of gasoline piston engines in airplanes, which are now the last large user of leaded fuel.

 

 

The article is claiming that a diesel-engined prop plane that can cruise at over 400 MPH at a 50,000 foot altitude, seating 6 passengers in a cabin with an aisle that allows standing up, that such a craft could indeed replace small, business jets.  And do so with a small fraction of the fuel consumption.

Yeah, yeah and yeah, besides the diesel engine, the performance of this thing is dependent on on laminar air flow over both the wings and fuselage, where laminar flow has been known for a very long time in aeronautical circles but thought to be unachievable in everyday practice.  The article explains that even the slight bump from a countersunk rivet as used in conventional aluminum aircraft construction can cause enough turbulence to disrupt laminar flow.  This airplane use carbon fiber composites to have to necessary glass-smooth surfaces.

This prototype aircraft has no passenger windows, and maybe the seams of adding them will greatly increase drag?  Maybe laminar flow is the aerodynamic drag counterpart to radar-evading stealth technology.  Like stealth with military aircraft, this may require high maintenance costs to maintain the glass-smooth finish, what with bug strikes and scratches caused by whatever air crews or ramp workers use to remove snow on the ground under winter storm condiitons? 

But at least it is an important insight into what efficiency gains are possible, if as the article states, the designer doesn't listen to the conventional wisdom on what won't work.  It also suggests that the endpoint of fuel efficiency improvements for airliners is far from reached, which affects competitiveness with high-speed trains.

It also suggests that high-speed diesels may allow non-electrified high-speed trains.

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?

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Posted by Paul Milenkovic on Saturday, October 30, 2021 7:05 AM

7j43k

You might have missed out on the Budd RDC's:  diesel.

 

 

Ed

 

The generic type of diesel self-propelled railroad passenger car is called a DMU, of which the Budd RDC that is no longer in production is just one example.

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?

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Posted by Paul Milenkovic on Saturday, October 30, 2021 7:36 AM

The jet engine is patterned after the Brayton Cycle whereas the diesel is patterned after the Diesel Cycle.

True, that, the classical Diesel and Brayton Cycles add heat by burning fuel at constant pressure.  The difference is that in the Diesel Cycle, the volume into which the expansion is done is limited to the volume used for compression because they use the same cylinder and piston.  As a consequence, the exhaust valve opening (EO) even on a Diesel results in a "blow-down" of the sudden release of the residual pressure.

The Brayton cycle fully expands the gas charge to ambient pressure, so there is no blow-down.  Brayton's original engine used separate cylinders for compression and expansion; modern Brayton cycle engines use separate compressor and expander turbine blades to do this as in jet engines.

In the steam locomotive world, a piston steam engine has such a blow-down at exhaust opening (EO) whereas a steam turbine does not because there is no piston and no exhaust valve.

Furthermore, modern diesel engines follow more closely the Otto Cycle in that they inject their fuel quickly and at very high pressure, and combustion takes place nearly at constant volume.  This is a Good Thing (tm), because it improves diesel engine efficiency in relation to the original Diesel Cycle, where the fuel injection took place at a more constant chamber pressure and increasing volume owing to lower injector pressure or other factors.

Finally, diesel engines are compression ignition -- the fuel is chosen and the compression pressure is made high enough that the fuel droplets catch fire as soon as they leave the injector.  Especially with the much lower pressure ratios of the earlier jet engines, compression ignition is not possible, and maintaining combustion of a running gas turbine required maintaining some manner of a hot surface in the combustion chamber or other provision for flame holding.

But as a practical matter, Diesel engines require pistons and connecting rods and a crankshaft.  Unlike Brayton's original engine along with some attempts at jets in the 1940's, jet engines use continuous-flow rotating turbines.  This is an important distinction because with modern materials used in turbines, jet engines can operate many more hour than diesels before they need to be torn down and rebuilt.  Also, turbines are much more lightweight for use in aircraft where weight is more critical to acceptable performance than with a train rolling on steel wheels against steel rails.

It is one of life's mysteries as to why railroad locomotives still use piston engines when apparently pistons have been the steam locomotive of the aircraft world replaced by turbines.  Steam ships have long gone from reciprocating pistons to rotating turbines.  Turbines were supposed to rule, with everything from not only gas turbine ships to gas turbine cars, gas turbine trucks and buses and even gas turbine trains.  Not only has the diesel locomotive fought off the gas turbine replacement, it is my understanding that the current generation of container ship uses low-speed direct-drive double-acting two-stroke diesel engines?

And it appears technology is coming full circle that pistons (!) may start replacing jet aircraft?  What a world and a time to live in!

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?

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Posted by BEAUSABRE on Saturday, October 30, 2021 10:07 AM

Paul Milenkovic
Yeah, yeah and yeah, besides the diesel engine, the performance of this thing is dependent on on laminar air flow over both the wings and fuselage, where laminar flow has been known for a very long time in aeronautical circles but thought to be unachievable in everyday practice.  The article explains that even the slight bump from a countersunk rivet as used in conventional aluminum aircraft construction can cause enough turbulence to disrupt laminar flow.  This airplane use carbon fiber composites to have to necessary glass-smooth surfaces.

"  The North American P-51 Mustang was the first aircraft intentionally designed to use laminar flow airfoils. However, wartime National Advisory Committee for Aeronautics (NACA) research data shows that Mustangs were not manufactured with a sufficient degree of surface quality to maintain much laminar flow on the wing. The Royal Air Force (RAF) found that the Bell P-63 Kingcobra, despite being designed with laminar airfoils, also was not manufactured with sufficient surface quality to have much laminar flow."

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Posted by Paul Milenkovic on Saturday, October 30, 2021 12:18 PM

BEAUSABRE

 

 
Paul Milenkovic
Yeah, yeah and yeah, besides the diesel engine, the performance of this thing is dependent on on laminar air flow over both the wings and fuselage, where laminar flow has been known for a very long time in aeronautical circles but thought to be unachievable in everyday practice.  The article explains that even the slight bump from a countersunk rivet as used in conventional aluminum aircraft construction can cause enough turbulence to disrupt laminar flow.  This airplane use carbon fiber composites to have to necessary glass-smooth surfaces.

 

"  The North American P-51 Mustang was the first aircraft intentionally designed to use laminar flow airfoils. However, wartime National Advisory Committee for Aeronautics (NACA) research data shows that Mustangs were not manufactured with a sufficient degree of surface quality to maintain much laminar flow on the wing. The Royal Air Force (RAF) found that the Bell P-63 Kingcobra, despite being designed with laminar airfoils, also was not manufactured with sufficient surface quality to have much laminar flow."

 

The linked article mentions the laminar flow P-51 as not being all that laminar flow, but the designer of this new airplane claims to get it to work this time by using glass-smooth composite materials.  I guess we shall see.

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?

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Posted by Erik_Mag on Sunday, October 31, 2021 1:07 AM

Paul Milenkovic

Maybe that V-12 engine could power the next generation of diesel multiple unit (DMU) trains?

The Continental aircraft diesel engines have reccomended TBO's of 2,000 hours. I would expect that a DMU would expect to be in use for at least 6 hours per day, which means that the engines would be overhauled once a year. These overhauls can cost a substantial fraction of the price of a new engine. It probably would make more sense to use a truck engine.

I would think that a diesel-electric hybrid transmission would be great for a DMU, as the battery would help with accelerating to track speed and recover braking energy.

The Celera 500L reminds me of a Dymaxion car with wings. It also brings in mnd the "area rule" for transonic and supersonic aircraft. The fuselage shape looks like it will handle pressurization. A 50,000' cruise altitude would get the plane above almost all of the weather and traffic, but I would not want to be on a polar route flight during a geomagnetic storm.

As for the "laminar flow" airfoil on the P-51: An article in a 1944 or '45 issue of Popular Science stated that the airfoil was chosen for high speed performance, in that it would go faster in a power dive than most other contemporary aircraft. The folks at North American were probably paying attention to the XP-38's encounters with compressibility (AKA transonic airflow). The Grumman Hellcat would go into an uncontrollable dive if pushed past Mach 0.75 - best chance for recovery was cutting power and ride the plane down to warmer and denser air where the plane could slow down below M 0.75.

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Posted by Overmod on Sunday, October 31, 2021 9:31 AM

Paul Milenkovic
It is one of life's mysteries as to why railroad locomotives still use piston engines when apparently pistons have been the steam locomotive of the aircraft world replaced by turbines.

There is little mystery.  The answer lies in 'turndown' efficiency, as has been noted repeatedly here for the UP turbines and the TurboTrain PT-6 derivatives.

I first saw this stated succinctly in material from EPRI which indicated that below about 34% of capacity a positive-displacement peaking plant (I.e. large diesel genset) was more efficient than a gas turbine of any construction, with the heat recovery of GTCC even more severely affected (for the same sorts of reasons as on the Kitson-Still!)

Freight locomotives spend a great part of their lives idling, accelerating into a load, or operating at low notch to use the train's inertia efficiently.  Even passenger trains do not use high sustained  horsepower consistently until you get well above the 79mph range.  For most railroad services the most sensible turbine plant continues to be relatively small units run at constant efficient speed to help charge a traction battery... and this applies to a modern version of Kneiling's integral train or a HPIT just as it would to stack or loose-car operation.

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Posted by Overmod on Sunday, October 31, 2021 9:44 AM

Erik_Mag
It also brings to mind the "area rule" for transonic and supersonic aircraft.

But that would call for constriction  of the fuselage at the wing roots, just about the antithesis of what the Otto design appears to be doing.  I think they're designing by analogy to motorgliders, minimizing the wing-root blending and keeping the effect of airflow over the wing in that region interacting with the 'laminar' flow over the fuselage in a way as... well, 'laminar' as possible.  Whether this requires careful attention to AOA or cruise trim remains to be seen in practice; I wonder if there will be some analogue to instrumented yaw strings in that area in flight to guide the pilot in fine-tuning the attitude...

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Posted by Erik_Mag on Sunday, October 31, 2021 1:53 PM

Noted...

Based on the 6'2" inside height, I would expect the cross section of the fuselage would be over 30 square feet and the first 4 or so feet of the wing on each may add up to maybe 3 square feet... In essence, a minor perturbation. The design also reminds me of the Albacore hull, which set submarine speed records. I suspect the plane would require less enrgy per passenger mile than a train running at 220mph.

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Posted by rdamon on Sunday, October 31, 2021 2:59 PM

Forward visibility looks impared as well.  Maybe they need a Concorde nose :)

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Posted by Shadow the Cats owner on Sunday, October 31, 2021 5:24 PM

Or a wide angle array of cameras on the nose.  There's a push to eliminate side mirrors on cars replacing them with cameras on cars now.  

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Posted by Backshop on Sunday, October 31, 2021 6:34 PM

I doubt this plane will ever be a commercial success.

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Posted by kgbw49 on Sunday, October 31, 2021 9:31 PM

Not the first elongated flying egg. Just engines in a different location.

https://www.robertnovell.com/the-curtiss-c-46-the-airplane-history-has-forgotten-december-14-2018/

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Posted by CSSHEGEWISCH on Monday, November 1, 2021 10:04 AM

Shadow the Cats owner

Or a wide angle array of cameras on the nose.  There's a push to eliminate side mirrors on cars replacing them with cameras on cars now.  

 
I would hope not.  Depth perception and location judgment seem to be better with outside mirrors than looking at a screen inside the car.
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Posted by Flintlock76 on Monday, November 1, 2021 10:17 AM

CSSHEGEWISCH

 

 
Shadow the Cats owner

Or a wide angle array of cameras on the nose.  There's a push to eliminate side mirrors on cars replacing them with cameras on cars now.  

 

 

 
I would hope not.  Depth perception and location judgment seem to be better with outside mirrors than looking at a screen inside the car.
 

They are, at least in my case.  I rented a car several years ago that had a back-up camera and screen on the dash.  I thought it was worse than useless and did the old-school thing of turning around in the seat and using the "Mark-1 Two Eyeball Unit."

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Posted by Overmod on Monday, November 1, 2021 10:23 AM

Rear-view cameras for driving (as opposed to backup aids) are a disaster and the reason has long been recognized.  Mirrors focus the image at the apparent distance of the objects "in" them -- so drivers focusing on the sight picture ahead of them can check mirrors without shifting focus or haptic recognition.  Most screens or earlier CRTs require drastic shift in accommodation followed by reaction time to extract position from the flat image, and this is reversed when looking back ahead.  This leads to fatigue, not always directly realized, over time, and the problem is magnified in bad weather or at night when 'situational awareness' should be at its height.

I might add that I am pathologically unable to back up effectively with mirrors, but quite able to drive in reverse at road speed using the 'arm over the seat' position looking out the rear window...

What STCO mentioned is a standard approach for autonomous vehicles, using sensor fusion from the multiple cameras for machine vision.  A fascinating use of this is currently provided on some trucks and ag equipment, where synthetic vision of the 'sight picture' as if there were no engine hood or other structure in the line of sight is provided.  This is a dramatic advantage the first time you see it in action... but I continue to think it is better as a ground reference than a driving aid at high speed.

I would note that my old synthetic-vision stereo headset for AR over 30 years ago used the Reflection Technologies optics, which presented a clear image at the eye's far focus, and this would not suffer the accommodation problems if it were to be used for either rear-view or 'augmented' driving (e.g. with IR night enhancement).

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Posted by BaltACD on Monday, November 1, 2021 10:45 AM

Overmod
Rear-view cameras for driving (as opposed to backup aids) are a disaster and the reason has long been recognized.  Mirrors focus the image at the apparent distance of the objects "in" them -- so drivers focusing on the sight picture ahead of them can check mirrors without shifting focus or haptic recognition.  Most screens or earlier CRTs require drastic shift in accommodation followed by reaction time to extract position from the flat image, and this is reversed when looking back ahead.  This leads to fatigue, not always directly realized, over time, and the problem is magnified in bad weather or at night when 'situational awareness' should be at its height.

I might add that I am pathologically unable to back up effectively with mirrors, but quite able to drive in reverse at road speed using the 'arm over the seat' position looking out the rear window...

What STCO mentioned is a standard approach for autonomous vehicles, using sensor fusion from the multiple cameras for machine vision.  A fascinating use of this is currently provided on some trucks and ag equipment, where synthetic vision of the 'sight picture' as if there were no engine hood or other structure in the line of sight is provided.  This is a dramatic advantage the first time you see it in action... but I continue to think it is better as a ground reference than a driving aid at high speed.

I would note that my old synthetic-vision stereo headset for AR over 30 years ago used the Reflection Technologies optics, which presented a clear image at the eye's far focus, and this would not suffer the accommodation problems if it were to be used for either rear-view or 'augmented' driving (e.g. with IR night enhancement).

On my race car I have both forward and rearward facing cameras that I can edit into a combined finished video.  When watching the finished video, my 'initial reaction' of where I wll see a car(s) that are overtaking me is wrong - my mind is in the 'real world' of the forward facing camera, not the rearward facing camera.

With the finished video not giving me the opprotunity to 'put my arm over the seatback' to frame my vision things get turned around.

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Posted by rdamon on Monday, November 1, 2021 3:09 PM

Aircraft really just need  help finding the centerline of runways and taxiways. Not parallel parking percision.

Synthetic vision or HUD systems may work.

http://www.nexairavionics.com/hot-topics/synthetic-vision/

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