Kawasaki entering GA market

Longer range air taxi, maybe. Quad copter with small battery to fly 15-30 minutes, plus generator to recharge in flight. Just spit balling.
 
Salty said:
I don’t understand why people think hybrid makes any sense in aircraft. It only works in cars because of stop and go traffic and regen braking. You don’t stop or sit at lights in an airplane. Once the battery is drained you’re hauling dead weight. Stupid idea.
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yes and no. That is a very commonly held belief. However, Toyota is probably the world leading expert on hybrid motors in cars.
Toyota has announced the Renaissance engine which will be for what is known as a series hybrid. Basically a genset with a battery. The stated reasons why Toyota is doing a clean sheet engine is design are the following:
1. Car engines have high variable speed requirements when directly powering the wheels. The future to gain efficiency in engine design is all around engines designed to operate in very limited RPM and power bands.
2. The dual power train weight and complexity are now out weighing the additional battery weight along with the efficiency loss of energy from chemical to mechanical to electrical to mechanical.

I have seen a few articles by pundits saying Toyota is pushing the thermal efficiency from the high 30s to as much as the high 60s with super high compression in the new engine designs. Not sure what is believable since I have not seen any claims from Toyota except to say it is much more efficient. BWTHDIK?

Tim
 
Jim K said:
I was thinking that it might allow a smaller, more efficient, high-rpm, mogas engine (like the Kaw), operating a generator instead of having to have a PSRU to step down from 8500+ to 2700. However, by the time you add up the weight of the motor, generator, engine, and battery, it's much heavier than a good old Lycosaur.

An interesting suggestion from AI when I was working on this...a series hybrid. Instead of a high compression 200hp Lyco, a 150hp Rotax with a small motor to make up the difference on takeoff and climb. AI claimed it could be done with about the same weight as an io-360. Benefit would be mogas and higher efficiency. Downside is way more cost & complexity.

Every time I try to come up with a new way to skin the cat, the "antique" designs don't look so bad after all...
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Ai also told you 40 bucks to chrome valve covers.
 
Salty said:
I don’t understand why people think hybrid makes any sense in aircraft.
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In its basic format, efficiency and power output/weight. But don't quite follow why you think the battery would be drained? In the 2 projects I'm familiar with, the hybrid propulsion unit was basically a small purpose-built "APU" that provided power for ground movement and cruise flight at which time it would also charge the battery pack. The onboard battery pack provided initial startup and additional power requirements for take-off and landing phases plus it was the emergency power supply to land if the hybrid power system were to fail. The KW system used in the VoltAero project above does the same except adds another level redundancy.

So given a conventional aircraft recip power efficiency is around 30% compared to about 75% for a hybrid system, it opens a path to get more power at the prop from a smaller power package. Unfortunately, few to none of the hybrid systems will allow for any retro fits to existing aircraft for a number of reasons. People want new aircraft and want to use modern technology and this is the path that is getting all the money. Its also one of the reasons you see Kawasaki, Hyundai, Toyota, Honda, etc. all making moves to this side of the industry. Will it eventually work down to the recreational level? I think so just not tomorrow.
 
Jim K said:
I was thinking that it might allow a smaller, more efficient, high-rpm, mogas engine (like the Kaw), operating a generator instead of having to have a PSRU to step down from 8500+ to 2700. However, by the time you add up the weight of the motor, generator, engine, and battery, it's much heavier than a good old Lycosaur.
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I can see a genset running an electric motor. That *could* make sense from a packaging and weight standpoint. Insert a big enough battery in there to do anything and you're upside down in weight, at least the way I see it.
 
kyleb said:
I can see a genset running an electric motor. That *could* make sense from a packaging and weight standpoint.
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IT does make sense in certain situations and there are a number examples flying right now. With batteries its more than just weight but capacity as well which is the limiting factor. Hence the hybrid route became economically iable until battery technology or fuel cell tech can move to the next level. The one limiting factor to the hybrid side was most components were OTS units built for different purposes. Now that there are components built specifically for these type applications you will see a marked increase in their use.
 
Enjoy that extra 10 minutes of range with 300 pounds less useful load.

I guarantee you’d get more range per pound by adding more fuel than by adding an electric motor, battery, wiring, and control equipment.
 
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Salty said:
Enjoy that extra 10 minutes of range with 300 pounds less useful load.
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One version of hybrid is to use the battery (ala F1) in situations where a boost in power is needed briefly. Such as takeoff or landing, particularly for a VTOL system. I still don't know if that benefit justifies the weight.
 
Bell206 said:
Except you'll find the hybrid powertrain projects that are not funded by “green dollars” are the only ones that are succeeding and making to the certification levels. While green power is a selling point in some circles, its not the main reason driving the advancements from what I’ve seen.
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Perhaps the difference is that projects designed to garner "green dollars" (which I take to mean as environmentally motivated grant money -- often public funds -- rather than descriptive of the US greenback) are not motivated to produce a certifiable, marketable, viable, usable powerplant, but rather those projects have exhausted their purpose as soon as the grant check clears.
 
kyleb said:
I still don't know if that benefit justifies the weight.
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Except its not just weight per se but power density: hp/lb or kW/kg. So when you add in the efficiencies of an electric system the power density difference between a conventional recip and a hybrid start to expand. While most hybrids use turbine-generators its interesting Kawa is using a gas recip. However, I assume that has something to do with the H2 version if I had to guess.

DJTorrente said:
but rather those projects have exhausted their purpose as soon as the grant check clears.
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Basically yes. But while they were still motivated to produce a finished product, their design selection usually was not a viable solution to any underlying, non-climate directed problem. From my vantage point having been around the UAM concept well before climate initiatives started to fund green aircraft, there was always a core group of developers for eVTOLs, aircraft hybrid propulsion, etc. who were pursuing different goals and solutions for UAM. So it would have happened whether there were climate issues or not.
 
Bell206 said:
Except its not just weight per se but power density: hp/lb or kW/kg. So when you add in the efficiencies of an electric system the power density difference between a conventional recip and a hybrid start to expand. While most hybrids use turbine-generators its interesting Kawa is using a gas recip. However, I assume that has something to do with the H2 version if I had to guess.
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The other big advantage of electric power is engineering flexibility. Recip tilt rotors are so mechanically complex that only the United States has fielded operational aircraft, and those with only two rotors. Yet 4 or 8 tilting rotors driven by electric power is almost trivial.

However, all-electric aircraft are limited by battery weight, which is a function of the poor energy density of current battery tech, a point electrical aircraft detractors never tire of pointing out.

A hybrid approach might capture the best of both worlds. Electric power for ease of engineering. Recip generation for energy density. Small battery to buffer power demands for takeoff and emergencies.

Never say never.
 
DJTorrente said:
Perhaps the difference is that projects designed to garner "green dollars" (which I take to mean as environmentally motivated grant money -- often public funds -- rather than descriptive of the US greenback) are not motivated to produce a certifiable, marketable, viable, usable powerplant, but rather those projects have exhausted their purpose as soon as the grant check clears.
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Hybrids just make more financial sense for most people when considering a car; they have become so efficient.
And when you look at the direction hybrids are going, as I referenced above with Toyota, the focus is on making the ICE significantly more efficient since regen breaking and most other aspects have pretty much reached the point of diminishing returns.

To increase ICE efficiency, requires a fundamental change in approach and rethinking about how the ICE works, the system requirements... And this will take me way outside my wheelhouse. Note: I am going based on what I have read, and my limited understanding.

As long as the ICE has to have variable speed and power, there is an effective cap on how efficient the engine can be.
To address the thermal efficiency and make the ICE significantly more efficient, it will need new engine designs. High RPM, short stroke, wide bore, extremely high compression (I tried to follow one paper that suggested compression ratios as high as 50 to 1), high pressure fuel injection from multiple jets, multi spark/ignition, constant/single speed, full power...

Most of these attributes are the opposite of what makes a good ICE design for a car engine. However, you will notice that there is a very strong overlap with aviation and with gensets. I believe this is why you see Toyota, Kawasaki, Honda and others entering new engine markets. And also why John Deer, Kabota and other genset companies should be paying attention.

Tim
 
Ed Haywood said:
Electric power for ease of engineering.
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And scalability. They are currently testing 2.5 MW electric engines for aircraft hybrid propulsion systems. Thats 3000+ hp. And on the power side I believe they are at 1 MW for turbo-generators. I think you'll see the aviation hybrid power side get smaller more powerful and fill the gap until battery tech gets to the next level, or maybe even create its own class of aircraft.

tspear said:
To increase ICE efficiency, requires a fundamental change in approach and rethinking about how the ICE works, the system requirements...
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From what I've seen it depends on what part of that efficiency scale you're working on. For example, an ICE ran at a constant RPM will be a lot more efficient than an ICE that runs at a variable RPM. Or in the case of a turbine engine, you can increase efficiency by 20-30% simply by raising the combustion temps. So there still is a lot that can be done with existing ICE architecture efficiency-wise without a complete redesign.
 
Bell206 said:
From what I've seen it depends on what part of that efficiency scale you're working on. For example, an ICE ran at a constant RPM will be a lot more efficient than an ICE that runs at a variable RPM. Or in the case of a turbine engine, you can increase efficiency by 20-30% simply by raising the combustion temps. So there still is a lot that can be done with existing ICE architecture efficiency-wise without a complete redesign.
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Yeah, from what i have read over the last couple years, I will admit it is all from pundits, the justification from Toyota, Honda, and Subaru (pretty much all the major Japanese auto manufacturers, and I assume Kawasaki would have the same concepts) is that existing designs when converting have very limited efficiency gains which are well known. They are looking at fundamental breakthroughs to dramatically increase the thermal efficiency.

Tim
 
Bell206 said:
So there still is a lot that can be done with existing ICE architecture efficiency-wise without a complete redesign.
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For autos, the best thing we could do would be go hybrid with everything. Think of the F250's and Tahoe's in stop-n-go traffic wasting all that kinetic energy every time they touch the brakes. Regen braking and a modest battery would reclaim a huge portion of that.
 
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kyleb said:
For autos, the best thing we could do would be go hybrid with everything. Think of the F250's and Tahoe's in stop-n-go traffic wasting all that kinetic energy every time they touch the brakes. Regen braking and a modest battery would reclaim a huge portion of that.
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I get the appeal of Teslas. No water pumps, alternators, radiators, exhaust---none of that to deal with. The last thing I would want is to have all those potential points of failure with some hybrid system superimposed on top of it----even more complexity and more points of failure---no thanks.
 
I can’t wait to see it. Should be exciting to have something new on the market.
 
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