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Series Hybrid into Plane, need help

14578 Views 39 Replies 8 Participants Last post by  DaDeemster
Hello all, after spending a decent bit of time polishing back up on my electrical knowledge i decided i'd finally move on to the public feedback stage of my plan, this is my first post On this awesome forum. I'm aware of this not being an airplane forum , but with this being the goto place for all things "electric vehicle" i figured it couldnt hurt

The objective of this build is try and find a clever way to shoehorn all the necessitys of a typical series hybrid into the plane without the plane tipping the scales, and cost effectively.

Ok so the build is to be based in one of the following (its not important to have alot of plane backround knowledge) they are 20k and under planes with relatively a decent positive history

Sonex aircraft -
Pulsar Xp -
Sonerai II -

**The Ac electric motors i'm leaning towards** are the Enstroj Emrax motor and the Hpevs ac51-76.
But since the Motors are comparable and the Emrax has a drastically better power to weight i'm gonna go with it (22lbs roughly) i was considering possible two so as not to stress the motor , unless new affordable alternatives have been released SO-

Emrax 228 -

** Motor For Generator ideas** - (thinking compact, powerful (for when i need to bump the rpm's up to get the batterys some immediate juice

**This is the Dyno of a ICE motor that is slightly more powerful then it needs to be for the drive motor application -

-The motor im wanting to use to power the On Board Dc Generator is a ar741 rotary wankel motor from ( thier site is semi down)
i was able to find one on the internet
-i was also able to find a 30-40 horse sachs rotary motor, pull start
-i also found some running vintage snowmobiles that have the 38hp Sachs rotary motor

^^ will these motors suffice my generator power needs? direct Hp to Kw conversion wise they do even at peak torque range but is that all that matters?

Which brings me to my next dilemma, and this is where things start getting hazy- My Dc generator needs be able to directly convert as close to 100% of the rotary engine output power as possible but i dont know what dc generator make/size is best for matching it to the motors above. or if i need to run a reduction drive (i'm thinking not)

Secondly, is it really as simple as hooking the rotary to the generator and then finding a way to hold it at preset throttle positions for different charge rates
Can it go straight from the Dc Generator to main battery terminals? and if not then what is the direct most way. Also does Generator need modifying

Also has anyone had any experience with foreign batteries? I've only heard non educated guess'. The deals are amazing and look well put together



And based off of someones post in this forum and the recommended voltage range for the motor i'm thinking the second battery link option would be best since its more voltage mediocre amp hourage , but since i will be so many batteries above the voltage i need to make it to run consistently so i can just enjoy the benefits of a big pack with so-so amp hours (around 180-220lbs)

Also i'd probably use the Medium- High Voltage motor controller options that they have available on thier site

But to stay in theme, if anyone has alternatives that i could use. and also thoughts on using one heavy duty controller for Dual Emrax motors. They said its not what they would recommend but i'd like to know more anyway. two motors sounds like less wear on each motor plus it would give me a instant additional power range without putting strain on a single motor. but i'm kinda confused on this . If im applying 20kw continuous from the controller to the motor will it perform the same with dual motors under the same 20kw contin' on dual motors? and if not what would be different besides more potential torque? Would i need 40kw from the motor controller to get the same desired rpms? or would the dual motors be suffice with same 20kw from the controller?

P.S i know i'm new and i pretty much wrote an article but feel free to take your guys time responding, i have a feeling i'm gonna be on this site for awhile lol
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Hi Dadeemster

Why serial hybrid?
Each time you convert energy the gods of thermodynamics take a bite

Fuel - mechanical power about 30%
mechanical power - electricity - about 85%
electricity - mechanical power - about 85%
(If it goes into a battery then there are another two bites taken out)

The two 85% together are 72% - so you are losing 28%!

(And NO you will not get a large increase in efficiency using a smaller motor)

Better would be to use a parallel hybrid

With this you would use the IC engine to drive an AC motor/generator and the prop

In cruise the AC motor/generator would be effectively just a driveshaft

For more power use the electric motor, to recharge the batteries use the motor as a generator
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The only serial hybrids I am aware of are trains and BIIIG trucks (mining trucks)
And these are serial because of advantages in the drive train (lots of wheels to drive) despite the inefficiencies!

Now Parallel hybrids are common, Prius, Volt

For a plane you could use a smaller IC engine and use battery power to augment for the take-off and climb

All electric motors are also generators (some are easier than others)
For a plane I suspect brushes will be a NO NO - so you are stuck with AC
(all the brushes do is convert DC to AC)

I envision your IC motor back in the middle of the plane
You will have a long driveshaft to the prop (possibly with a gear down system)
Your electric motor will be in the middle of the long driveshaft

Take-off and climb
The IC engine will be on full power and the electric motor will also powering the driveshaft and the prop

The IC engine will be driving the prop - the electric motor is just there for the ride

Re-Charge - if you want to, cheapest is to plug it in back home
The IC engine is running a bit more than cruise and the motor is vampiring a bit of power off it to recharge the batteries while most of the power is going through to the prop

Not at all sure it is worth the extra complexity

You could have something like the Voyager (Bert Rutan) with a tractor prop at the front powered by the IC and a pusher prop at the back powered by the electric
No re-charge with that setup
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If anyone doubts the potential for application of series hybrids, wiki has pretty credible section on it -

Credible - BUT wrong
Those efficiency figures are nonsense -
It's like comparing a 1960's V8 with a modern 4 Cyl,
Restricting the speed range MAY buy you a 10% increase in efficiency

The only way it will get you a 50% increase in efficiency is if the engine was very poorly optimized in the first place

Also note
The Volt and Prius are both parallel hybrids - NOT series
Don't forget regen during descent! You have to bleed off a lot of speed; why use drag when you can recharge for your next takeoff?
I think you will find most aircraft continue to use power to;

Flatten the glide slope
compensate for the extra drag of wheels/flaps

So there is nothing left to re-gen
You are swapping range/glide angle for re-gen power

You pay energy to climb - and you can get some of that back on the descent

But it's a bad deal as every time you convert energy the gods of thermodynamics take their cut
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