Serial / Series Hybrid Tracker

[NeilBlanchard]

An interesting use for a serial hybrid:


(click on image for link)

The technology, which is intended for later use also in large-scale aircraft, will cut fuel consumption and emissions by 25%, compared to today’s most efficient aircraft drives, according to Siemens.

Based on Diamond Aircraft’s HK36 Super Dimona, the E-Star’s propeller is powered by a 70 kW electric motor from Siemens. Electricity is supplied by a small Wankel engine from Austro Engine with a generator that functions solely as a power source. A Siemens converter supplies the electric motor with power from the battery and the generator.

Fuel consumption is low since the combustion engine always runs with a constant low output of 30 kW. A battery system from EADS provides the increased power required during takeoff and climb. The battery is recharged during the cruising phase. The plane is able to start noiseless with the electric drive and can fly over long distances. During test flights, it was airborne for about two hours.

[Emphasis is mine.]

[rmay635703]

Originally Posted by dcb

Dude, do an accounting of the losses of a series drivetrain, just once, without the rose colored glasses. The "efficiency envelope" for an ICE is also much larger than steady state cruise. This seems like a very unbalanced viewpoint you have.

Yes all drivetrains have losses, but driving the wheels directly gives the volt a 15% boost in efficiency, so that should be a clue as to how sloppy series is.

Military turbines top out at 56% eff, single RPM dc generators top out at about 95% eff, dc charge controllers top out at 98% eff depending on load, battery charging tops out at 80% eff with power to the wheels not having this loss.

So lets see, EVEN IF we charge the battery instead of directly driving the electric motor you end up with a minimum 28.8% EFF charging batteries and a max EFF of 52.1% driving the electric motor.

Why don't I take the motor loss in account? Because all of the ICE BS never does either, ICES also run 0%-35% real world EFF depending on load

Cheers
Ryan

[jamesqf]

Originally Posted by NeilBlanchard

An interesting use for a serial hybrid:

Had a little trouble believing that one, until I read this in the linked article: " The partners are presenting the two-seater motor glider..." So it has the motor running & recharging the battery when a normal motor-glider would be soaring with engine off.

I've also seen pure electric self-launching sailplanes.

[dcb]

Originally Posted by NeilBlanchard

...which is intended for later use also in large-scale aircraft

not sure about motor glider here.

Originally Posted by NeilBlanchard

, will cut fuel consumption and emissions by 25%, compared to today’s most efficient aircraft drives, according to Siemens....supplied by a small Wankel engine

Cut consumption by 25%, in the same breath as "Wankel"? My BS alarm is going off.

Electric airplanes are also a bonehead move, that is the one application that would benefit most from liquid fuel, preferably of the renewable variety. Energy density/energy to weight of electric is atrocious by comparison, and size and weight are bad for airplane efficiency.

[dcb]

Originally Posted by rmay635703

Military turbines top out at 56% eff, single RPM dc generators top out at about 95% eff, dc charge controllers top out at 98% eff depending on load, battery charging tops out at 80% eff with power to the wheels not having this loss.

So lets see, EVEN IF we charge the battery instead of directly driving the electric motor you end up with a minimum 28.8% EFF charging batteries and a max EFF of 52.1% driving the electric motor.

Why don't I take the motor loss in account? Because all of the ICE BS never does either, ICES also run 0%-35% real world EFF depending on load

What? So you are going with %56 engine efficiency now? and %95 for generator efficiency, and %98 efficiency for the controller? And no mention of motor efficiency? Can you put your hands in your head?

Are you also assuming that you have to have a series electric hybrid to use a turbine? Turbines have been powering wheels for a long time, i.e. the hydrokinetic transmission in an M1 tank.

How does any of this apply to a "modder" anyway? You going to put a turbine on your citicar?

[bwilson4web]

In hybrid electrics, I've found examples of:

• electric power <<< engine power - examples are GM's and other autostop, BAS, systems, ~5 hp EV vs. ~170 hp ICE. These are 'greenwash' systems such as the Chevy Malibu.
• electric power torque assist << engine power - examples are the Honda hybrids, ~15 hp EV vs. ~100 hp ICE. Because the engine torque provides the bottom end, a substantially smaller engine can still provide adequate driving experience.
• electric power drive < engine power - examples are the Toyota drive hybrids, 30 hp EV vs. ~70 hp ICE (NHW11.) The car has a non-trival amount of electric power, enough to handle slow speeds, ~25 mph, for distances up to a mile.
• electric power drive ~= engine power - examples are the Toyota plug-in hybrids. I don't have the EV vs. ICE power ratios (too lazy to lookup) but they extend the EV distances to 10 miles and speeds up to 50 mph.
• electric power > engine power - examples are the GM Volt and several concept cars including the Jaguar C-X75. Sometimes called extended range EV, the only production version is not so impressive on gas power.

That a hybrid electric can be built does not mean it should be. In the case of the Jaguar C-X75, this is an experiment investigating the limits. I support experimentation but there is a big gap between what can be built, a lab experiment, and a practical hybrid electric.

One serious flaw of the Volt is not so good gas assisted mileage. What this tells me is there is an efficiency problem in that design. Without a Volt to test, I can not diagnose the problem(s) but the gross mileage numbers indicate they are not able to equal the Toyota efficiency. It is not even close when the vehicle volume and non-electric, miles per gallon. But it is also GM's first production hybrid of merit ... the Precept was the unbuilt, GM prototype of the Volt, 10 years ago.

Bob Wilson

[dcb]

here is more info on that airframe and the stock 80hp engine
Diamond HK36 TC Super Dimona performance and specifications

I understand the concept, but a motor glider isn't the best example (especially since the prop can feather). I have little doubt that pulse and glide in this plane would simply blow away any cockamamie gizmo designed to automate away skill, and not bother anyone "behind" you.

And I have to think that a second engine (or extra cylinders anyway that can disengage) would solve the problem of right sizing the engine for best bsfc constant cruise and acceptable takeoff/climb power with less weight and size and cost penalty. That is what Rutan did with the voyager.

[jamesqf]

Originally Posted by dcb

Electric airplanes are also a bonehead move...

Not so bonehead for the self-launching sailplane application. You only need 10-15 minutes run time, and you don't have to mess with gas, starting, noise, vibration... It's basically all the advantages of my electric lawn mower over a gas one.

Might also look at how many electric RC airplanes (and helicopters) there are out there.

Cut consumption by 25%, in the same breath as "Wankel"? My BS alarm is going off.

In my experience (a lot of long-distance drives in a Mazda RX-3, back in the '70s), the Wankel isn't at all bad at a constant, fairly high RPM. It would cruise down the interstate for hours at 70+, but the varying speed & load in city driving would kill the mpg.

[dcb]

Originally Posted by jamesqf

Might also look at how many electric RC airplanes (and helicopters) there are out there.

That is what I do for a hobby actually, I prefer the non powered sailplanes personally (i.e. bungee launch). I have done fuel planes, and they ARE far superior in power to weight, as well as run time, and sometimes cost, but they are also toys, so spilling nitro in your back seat takes a lot of the fun out of it. And they also don't generally have a payload like real planes do. You are advocating convenience over efficiency here, and the larger scale of a commuter plane means greater losses to avoid something as routine as refuelling a car.

It makes sense for a 10 minute for fun RC flight to carry batteries, but it doesn't make sense if you are serious about efficiency on a larger scale.

[NeilBlanchard]

This is the Siemens serial hybrid airplane:


(Click on image for link)