Would anyone be interested?

[AH-1 Cobra Pilot]

18 minutes ago, jaylw314 said:

Compared to other true hybrids sedans, it gets better mileage, to the tune of about 41 mpg to 35 mpg.  So better, but not dramatically so.

My diesel Jetta gets over 50 mpg.  (It was even better before the "fix".)  Makes the hybrids look pretty crappy, I think.

[N201MKTurbo]

The hot setup would be a fuel cell powered airplane. 

A carnot heat engine can only do about 30% effiency at the temperatures humans live at. Fuel cells operate at efficiencies in the 90% range and modern electric motors can get effiencies in the 90% range too. You could extract about twice as much energy from a gallon of hydrocarbon fuel or more from pure hydrogen. 

The problem with fuel cells is they are wickedly expensive and fragile.

[AH-1 Cobra Pilot]

40 minutes ago, mooniac15u said:

Energy density is an interesting factor but it's not actually relevant until it becomes a constraint.  If the batteries provide enough range/endurance and allow for enough useful load for the mission it doesn't matter whether you could have accomplished the same with less total mass of fuel.  For example, a primary trainer that carries a student and CFI and never travels more than 20 miles from the airport.  I spent many hours training in a Cessna 172 that carried around about 200 extra pounds of fuel and several hundred pounds of unused useful load that I was never going to need during training.  A battery powered electric trainer would have been fine.

For longer range applications hybrid-electric fills the gap.  Running a liquid-fueled generator to power the electric motor allows both the internal combustion engine and the electric motor to always operate at peak efficiency.  DIesel/electric locomotives have been demonstrating this principle for decades.

The problem most people have in comparing energy technologies is that they tend to dismiss alternative technologies that are not a complete 1:1 replacement for fossil fuels.  The long term solutions will vary by application.

 

Please do the math before you respond like this.

To fly for one hour burning 6 gph of AVGAS:  6 gal/hr * 6 lb/gal * .453 kg/lb * 46.4 MJ/kg = 757.7 MJ/hr.  That is what a C-152 burns in gasoline at full power for one hour.  To determine how much battery you need to supply that energy, a lithium-ion battery has, at best, 0.875 MJ/kg.  Thus, 757.7 MJ/hr ÷ 0.875 MJ/kg = 865.9 kg = 1909 lb of batteries just to make a one hour flight.  I did not even factor in the conversion efficiency of electric power, which would make it even worse.  What percentage of aircraft weight is devoted to fuel?  Factor that in, too.

So 36 lb of AVGAS vs. 1909 lb of batteries?  My old C-152 held 26 gallons, or 156 lb.  That equates to 9.3%.  Using batteries would make for an airplane weighing over 20,000.  That would be one shitty airplane that no one would want to buy, except for people wanting to brag how 'green' they are.

As for hybrids, they are lousy on the highway, which is analogous to how we usually fly.  They are only good for city driving with lots of starts and stops, with the engine shutting down regularly.  Not at all applicable to airplanes.  You are far better off to avoid power losses from conversions and use a direct drive for your prop.

Train engines are diesel-electric for other reasons, mostly to have one engine drive several motors.  This may be applicable to multi-rotor craft, i.e. quad copters, but not airplanes.

[AH-1 Cobra Pilot]

49 minutes ago, mooniac15u said:

I guess you should tell these guys that they are wasting their time:

http://money.cnn.com/2017/11/28/technology/electric-plane-siemens-airbus-rolls-royce/index.html

https://www.reuters.com/article/us-aerospace-hybrid/boeing-backed-hybrid-electric-commuter-plane-to-hit-market-in-2022-idUSKBN1CA16A

 

 

They might be doing research, which may be a good expenditure of their time, but I oppose them wasting money, which is worse in that it probably comes from taxes.  Ask them what subsidies they are receiving for this nonsense.

[mooniac15u]

5 minutes ago, Ah-1 Cobra Pilot said:

Please do the math before you respond like this.

To fly for one hour burning 6 gph of AVGAS:  6 gal/hr * 6 lb/gal * .453 kg/lb * 46.4 MJ/kg = 757.7 MJ/hr.  That is what a C-152 burns in gasoline at full power for one hour.  To determine how much battery you need to supply that energy, a lithium-ion battery has, at best, 0.875 MJ/kg.  Thus, 757.7 MJ/hr ÷ 0.875 MJ/kg = 865.9 kg = 1909 lb of batteries just to make a one hour flight.  I did not even factor in the conversion efficiency of electric power, which would make it even worse.  What percentage of aircraft weight is devoted to fuel?  Factor that in, too.

So 36 lb of AVGAS vs. 1909 lb of batteries?  My old C-152 held 26 gallons, or 156 lb.  That equates to 9.3%.  Using batteries would make for an airplane weighing over 20,000.  That would be one shitty airplane that no one would want to buy, except for people wanting to brag how 'green' they are.

As for hybrids, they are lousy on the highway, which is analogous to how we usually fly.  They are only good for city driving with lots of starts and stops, with the engine shutting down regularly.  Not at all applicable to airplanes.  You are far better off to avoid power losses from conversions and use a direct drive for your prop.

Train engines are diesel-electric for other reasons, mostly to have one engine drive several motors.  This may be applicable to multi-rotor craft, i.e. quad copters, but not airplanes.

Your math is faulty.  The fuel contains that much energy but piston engines are only about 15% efficient in converting that energy to motion.  Electric motors are closer to 80% efficient.

http://www.pipistrel.si/news/wattsup-the-new-2seat-electric-trainer-took-its-maiden-fligh

 

[AH-1 Cobra Pilot]

2 minutes ago, mooniac15u said:

Your math is faulty.  The fuel contains that much energy but piston engines are only about 15% efficient in converting that energy to motion.  Electric motors are closer to 80% efficient.

http://www.pipistrel.si/news/wattsup-the-new-2seat-electric-trainer-took-its-maiden-fligh

 

You are right,  I did make a mistake.  Let us calculate it again.  125 hp * 1 hour * 3600 s/hr * 746 W/hp ÷ 0.8 ÷ 0.875 MJ/kg * 2.205 lb/kg = 1057 lb of battery to equal 6 gallons of gas , and the C-152 replacement would be 11,370 lb. (This is using the maximum energy density for the battery.  If you use the low number, multiply by about 2.4.)  [BTW, I had the Sparrowhawk conversion.]

As for your link, a 17 kWh battery can only power a 85kW motor for 12 minutes at full power, (114 hp).  Their rosy picture is of a one hour recharge.  How many 'touch and go's can you do in a day with that?  Not much of a replacement for your typical trainer aircraft.

Edited February 15, 2018 by Ah-1 Cobra Pilot

[jaylw314]

17 minutes ago, Ah-1 Cobra Pilot said:

Please do the math before you respond like this.

To fly for one hour burning 6 gph of AVGAS:  6 gal/hr * 6 lb/gal * .453 kg/lb * 46.4 MJ/kg = 757.7 MJ/hr.  That is what a C-152 burns in gasoline at full power for one hour.  To determine how much battery you need to supply that energy, a lithium-ion battery has, at best, 0.875 MJ/kg.  Thus, 757.7 MJ/hr ÷ 0.875 MJ/kg = 865.9 kg = 1909 lb of batteries just to make a one hour flight.  I did not even factor in the conversion efficiency of electric power, which would make it even worse.  What percentage of aircraft weight is devoted to fuel?  Factor that in, too.

So 36 lb of AVGAS vs. 1909 lb of batteries?  My old C-152 held 26 gallons, or 156 lb.  That equates to 9.3%.  Using batteries would make for an airplane weighing over 20,000.  That would be one shitty airplane that no one would want to buy, except for people wanting to brag how 'green' they are.

As for hybrids, they are lousy on the highway, which is analogous to how we usually fly.  They are only good for city driving with lots of starts and stops, with the engine shutting down regularly.  Not at all applicable to airplanes.  You are far better off to avoid power losses from conversions and use a direct drive for your prop.

Train engines are diesel-electric for other reasons, mostly to have one engine drive several motors.  This may be applicable to multi-rotor craft, i.e. quad copters, but not airplanes.

Did you include in the 6 gallons of Avgas the conversion effiency of energy in a gasoline engine?  I think the theoretical maximum is something like 25-30%, while electrical generation is about 80%.  That being said, if you take put energy in a battery and then use it to generate power, that's 80% twice, so maybe about 65% actual efficiency but still pretty darned good in comparison.

Hybrids can be good in all phases.  The Accord Hybrid I drive gets about 41 mpg on the highway and up to 49 mpg on the city roads.  A hybrid drive train would allow the gas engine to run at higher efficiency on the highway, too, by running at higher MAP instead of the typical low MAP during highway driving.  The extra power is pumped into the battery, and then the electric motor becomes the primary power source once the battery is charged up.  The gain is not as large as on city roads, but 41 mpg on the highway is significantly better than almost any equivalent pure gasoline car.

But yes, the battery issue is big, especially since the battery remains dead weight even if there is no juice in them.  You can't easily offload batteries to decrease weight like you can with fuel.

Anyone know how little fuel cells could weigh in theory?  If they could be made light, that would be ideal--they'd be far more efficient, 80-90% IIRC?  That means less fuel needed and you could offload uneeded fuel.  I suspect, though that fuel cells are super heavy since I only see them in buses...

[AH-1 Cobra Pilot]

27 minutes ago, jaylw314 said:

Anyone know how little fuel cells could weigh in theory?  If they could be made light, that would be ideal--they'd be far more efficient, 80-90% IIRC?  That means less fuel needed and you could offload uneeded fuel.  I suspect, though that fuel cells are super heavy since I only see them in buses...

The only fuel cells I have seen were used in spacecraft.  They were one-shot deals, with the benefit that the water could be drunk in an emergency.  (It was a nasty looking brown, but people who tried it said it tasted OK.) 

[1964-M20E]

On 2/14/2018 at 12:14 PM, Dream to fly said:

I'll take a leap and put this out there.  Would anyone like to form a group that pushes our Mooney planes forward into new technology?  Maybe we could meet in the Midwest at some fly-in diner and brainstorm and see what materializes.  Nothing like bucking the system and forcing change.

Back to the original question with 2 solid suggestions to improve our planes.

The mid-west is too far for me to fly for a day meeting.  However, magneto and electronic ignition have come up why not push for one of these?

E-mag and replace both left and right mags.  Would 30 of us going to E-mag enough to push harder for an STC?   The problem is we are probably looking at 5AMU installed.  Currently it is $2.6AMU for two E-mags themselves.  They would know that they could sell 60 E-mags.

http://www.emagair.com/pricing/

How many here would be willing to commit to approximately 5AMUs for full electronic ignition?

 

Second one would be the EFII.  Again the down side would be approximately 10AMUs installed with the current system running about 5AMUs alone.

http://www.flyefii.com/products/efii-systems/

How many here would be willing to commit to approximately 10AMUs for full electronic ignition and fuel injection?  This would get rid of the carburetor or mechanical fuel injection as well as the magnetos.  They claim somewhere around 4% efficiency increase????

[KSMooniac]

A few years ago there was a proposal for a "primary non-commercial" category under part 23 that would do wonders to revitalize our fleet. It would allow owners like most of us to modify and maintain our planes ourselves, so long as they're not used in commercial ops. We would be free to install the experimental avionics, autopilots, etc as well as do our own inspections and maintenance. I think we need to keep pushing for this!

Sent from my LG-US996 using Tapatalk

[Yetti]

Oh no we went to math.   So my Kubto tractor turns a max of 3000 RPM which last I checked was the same as a mooney prop.    I looked up the weight and it was alot more than the Lycoming A1A.    I would have to guess an aluminum block with replaceable steel sleeves like a big detroit could be made to the same spec

http://www.kubotaengine.com/products/engines/vertical-diesel

Improved upon old technology can be good too.

 

[Dream to fly]

Back to the original question with 2 solid suggestions to improve our planes.
The mid-west is too far for me to fly for a day meeting.  However, magneto and electronic ignition have come up why not push for one of these?
E-mag and replace both left and right mags.  Would 30 of us going to E-mag enough to push harder for an STC?   The problem is we are probably looking at 5AMU installed.  Currently it is $2.6AMU for two E-mags themselves.  They would know that they could sell 60 E-mags.
http://www.emagair.com/pricing/
How many here would be willing to commit to approximately 5AMUs for full electronic ignition?
 
Second one would be the EFII.  Again the down side would be approximately 10AMUs installed with the current system running about 5AMUs alone.
http://www.flyefii.com/products/efii-systems/
How many here would be willing to commit to approximately 10AMUs for full electronic ignition and fuel injection?  This would get rid of the carburetor or mechanical fuel injection as well as the magnetos.  They claim somewhere around 4% efficiency increase????

I'm in. All the way.

Sent from my E6810 using Tapatalk

[carusoam]

Interesting topics...

From engine’s to components.

From fuels to fuel cells.

From Classic materials to some pretty modern coatings on high tech castings.

From regulations to regulators, there has been a lot of modernization.

Keep the discussion flowing...

Wether it is here, or at a Mooney fly-in nearby, or a really cool fly-in in Florida...

Change is coming...

It is better to be prepared, thought through it, discussed it, before she gets here.   

Best regards,

-a-

[AH-1 Cobra Pilot]

19 hours ago, jaylw314 said:

The Accord Hybrid I drive gets about 41 mpg on the highway and up to 49 mpg on the city roads.  A hybrid drive train would allow the gas engine to run at higher efficiency on the highway, too, by running at higher MAP instead of the typical low MAP during highway driving. 

Very interesting.  If a hybrid gets better mileage in town than on the highway, this tells you something. 

The perfect scenario is when an engine's most efficient output is equal to the drag, (combination of friction, aerodynamic drag, etc.), and you are on level ground.  All of the engine power is devoted to pushing the vehicle forward; none goes to recharging the battery.  A higher speed results in extra power, all devoted to propulsion, not recharge.  Since your mileage is better in town, the greater part of energy produced is consumed in aerodynamic drag at the speeds you drive on the highway.  An 8 mpg difference is pretty substantial.  You must usually drive at least 30 mph above that magic 'best efficiency' speed.

This also shows why a hybrid airplane is silly.  Most of the distance people normally fly would be at a particular power setting, mostly at or above the point of maximum efficiency, meaning there is no 'waste' power to recharge a large battery bank.  The only scenario in which a hybrid might make sense is for a trainer specifically made to stay in the pattern doing T&Gs.

Again, using one engine to drive a generator/alternator to drive multiple electric motors can make sense in a quadcopter.  It depends on the size of your payload.

[N9201A]

Electric!

[N201MKTurbo]

One scenario where a hybrid might make sense in an airplane would be the elimination of a gearbox. You could have a small high reving Diesel engine driving a generator and then an electric motor driving the prop. This would eliminate the main barrier to using diesel power.

How about two small diesel power plants. One in each wing root. Multi engine redundancy with single engined safety.

Edited February 16, 2018 by N201MKTurbo

[mooniac15u]

22 hours ago, Ah-1 Cobra Pilot said:

You are right,  I did make a mistake.  Let us calculate it again.  125 hp * 1 hour * 3600 s/hr * 746 W/hp ÷ 0.8 ÷ 0.875 MJ/kg * 2.205 lb/kg = 1057 lb of battery to equal 6 gallons of gas , and the C-152 replacement would be 11,370 lb. (This is using the maximum energy density for the battery.  If you use the low number, multiply by about 2.4.)  [BTW, I had the Sparrowhawk conversion.]

As for your link, a 17 kWh battery can only power a 85kW motor for 12 minutes at full power, (114 hp).  Their rosy picture is of a one hour recharge.  How many 'touch and go's can you do in a day with that?  Not much of a replacement for your typical trainer aircraft.

You are definitely getting closer but there are still some problems with your calculations.  Let’s start with the battery.  Tesla has an 85kWH lithium-ion battery that they use in vehicles today that weighs 1200 lbs.  That would power the 85kW motor at full power for an hour so that part of your calculation was very close.  There are some new types of battery media that are in development that do better than that but let’s stick with an actual battery pack that exists today.  Your calculation is based on driving the motor at full power but you keep citing 6 gph for your C152 which is the fuel burn rate for 75% power.  So, for a fair comparison we only need 75% of the battery capacity which is about 900 lbs.  You have also failed to account for the different engine weights.  The C172 uses a Lycoming O-235 weighing in at about 250 lbs.  The engine in the Pipestrel weighs about 30 lbs.  Since the 30 lb engine is about the same weight as the 6 gallons of fuel that’s a wash and we can just subtract the 250 lbs from our 900 lb battery weight and we are at 650 lbs differential.  There’s probably some other weight to subtract like starter, alternator, vacuum pump but let’s just go with 650 lbs.

If the empty weight of a C152 is around 1100 lbs then the “full fuel” weight of the electric “1-hour” version is 1750 lbs and with 2 passengers it’s up to 2150 lbs. which is only about 500 lbs over the current max gross.  Since we’re talking about a new composite airframe rather than an actual C152 there should be some weight savings in the airframe.  It’s also not clear that you need that much battery because at “idle” the electric motor not only uses no power it actually generates power from the spinning propeller.

I’m not sure where your 11,370 lb calculation came from.  Based on the Tesla battery it looks like we need at most 900 lbs of battery per hour.  An 11,000 lb plane would have about 10 hours of endurance.  I think that’s more than your C152.  If we assume 4 hours endurance is needed that takes us from 2150 lbs to 4850 lbs.  That’s less than half your estimate and less than a quarter of your first 20,000 lb estimate.  I don’t think a 4850 lb aircraft is practical but let’s stay away from hyperbole in the estimates.

Also, the stated mission was not a full C152 replacement.  It was a trainer that did short hops in the vicinity of the airport.

[1964-M20E]

Well with regard to the hybrid aspect.  I could see where a smaller turbo charged engine diesel or gasoline as the main power source sized for cruise at max power and a smaller battery and electric motor that would give you a boost on takeoff for shorter takeoff run and faster initial climb out.  The electric motor would then become dead weight during the flight. Utilizing a sprag clutch arrangement it would allow the electric motor to be used in an emergency to extend glide ratio so you may end up being able to make an airport or avoid a particular obstacle during an of airport landing.  Detailed design would tell you how many T&G you cloud do before the battery power was used up for takeoff runs and you would need to fly around to let the battery recharge.

 

[AH-1 Cobra Pilot]

1 hour ago, N201MKTurbo said:

One scenario where a hybrid might make sense in an airplane would be the elimination of a gearbox. You could have a small high reving Diesel engine driving a generator and then an electric motor driving the prop. This would eliminate the main barrier to using diesel power.

You would be trading a gearbox for a generator and a motor.  I suspect the weight of the two would be more than the weight of the gearbox; plus, the efficiency losses would make it undesirable.

[timpercarpio]

How about a spray on coating using nano technology to keep ice off the airframe as well as the propeller?

[jetdriven]

16 hours ago, Yetti said:

Oh no we went to math.   So my Kubto tractor turns a max of 3000 RPM which last I checked was the same as a mooney prop.    I looked up the weight and it was alot more than the Lycoming A1A.    I would have to guess an aluminum block with replaceable steel sleeves like a big detroit could be made to the same spec

http://www.kubotaengine.com/products/engines/vertical-diesel

Improved upon old technology can be good too.

 

The biggest one there I could find was 74HP gross intermittent, which says not continuous duty. And it weighs 650lb and it’s CRDI and turbocharged which means complex. Make the block of aluminum and it won’t last as long, either. Tractor engines are reliable and long lived because they are massively overbuilt for their job  

 

http://www.kubotaengine.com/assets/documents/Brochures-Engines Tier 4/2016 June/07/v3307_cr_te4b_tie4b.pdf

[steingar]

Still a big problem in all this.  Once I fly my airplane for its full range I can land, fill it full of gas and take off again.  Not os certain how that's going to work with an electric.  As far as hybrids, 2 engines for every one sounds heavy, and it also sounds like 2 failure points for every power plant.  Enjoy the new stuff gents, I'll happily keep flying old school.

[jaylw314]

 

 

 

5 hours ago, Ah-1 Cobra Pilot said:

Very interesting.  If a hybrid gets better mileage in town than on the highway, this tells you something. 

The perfect scenario is when an engine's most efficient output is equal to the drag, (combination of friction, aerodynamic drag, etc.), and you are on level ground.  All of the engine power is devoted to pushing the vehicle forward; none goes to recharging the battery.  A higher speed results in extra power, all devoted to propulsion, not recharge.  Since your mileage is better in town, the greater part of energy produced is consumed in aerodynamic drag at the speeds you drive on the highway.  An 8 mpg difference is pretty substantial.  You must usually drive at least 30 mph above that magic 'best efficiency' speed.

Really, ANY engine should give you worse mileage on the highway than in town, since you are going faster and there is more drag.  That's the same problem with aircraft, right?  The only reason city driving comes out worse is because of the need to brake repeatedly, and that's true for all cars--hybrids just are not hurt as much by this as other cars.  THAT problem is not relevant to aircraft.

This is a fundamental problem with gasoline engines, in that their BSFC is generally worse at low throttle.  Since highway cruising often requires only 30-40 hp, only cars with pitifully small engines can be at their most efficient on the highway, if they can make it onto the highway in the first place!  Think old Volkswagen beetles.  Hence the reason for hybrids--you can use a more powerful (and more useful) engine, but still get better BSFC.

2 hours ago, Ah-1 Cobra Pilot said:

You would be trading a gearbox for a generator and a motor.  I suspect the weight of the two would be more than the weight of the gearbox; plus, the efficiency losses would make it undesirable.

The weight of a transmission is not trivial.  My subaru WRX transmission weighs about 350-400 lbs.  The Tesla sedan brushless electric motor weighs 70 lbs.  I'd trade 350 lbs for 140 lbs any day.  Also, gearbox efficiency is not 100%--depending on load, it can vary between 50-80%.  That's comparable to the 60% I guesstimated above for the generator-battery-motor efficiency.

 

 

[jaylw314]

3 hours ago, 1964-M20E said:

Well with regard to the hybrid aspect.  I could see where a smaller turbo charged engine diesel or gasoline as the main power source sized for cruise at max power and a smaller battery and electric motor that would give you a boost on takeoff for shorter takeoff run and faster initial climb out.  The electric motor would then become dead weight during the flight. Utilizing a sprag clutch arrangement it would allow the electric motor to be used in an emergency to extend glide ratio so you may end up being able to make an airport or avoid a particular obstacle during an of airport landing.  Detailed design would tell you how many T&G you cloud do before the battery power was used up for takeoff runs and you would need to fly around to let the battery recharge.

You wouldn't need a clutch, the motor could simply be directly connected to the main motor and the prop..  Today's brushless electric motors can run throughout the range of propeller RPM's without a problem, and the power controller can be set to "freewheel" the motor when no output or input power is used.  Teslas and some other electric cars use one brushless electric motor with no gearbox--the motor runs through the entire range 0-155 mph in one "gear". 

[AH-1 Cobra Pilot]

29 minutes ago, jaylw314 said:

Really, ANY engine should give you worse mileage on the highway than in town, since you are going faster and there is more drag.  That's the same problem with aircraft, right? 

No, just as in aircraft, you have several friction/drag curves and the engine has its own efficiency curve.  Where these curves meet, essentially, is the best speed vs. fuel burn.