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Series Hybrid into Plane, need help

14570 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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also for proof of concept or to see where i'm coming from minus the serial hybrid addition

When this guy first made this electraflyer-c it was just a DIY project

And this is the electric sonex
I'm liking where your coming from but before i go onto discussing parallel i'll give you the logic im working with at the moment

1.I figured i'd be using emrax 228 which hovers in 92-96% efficiency ( so thats pretty decent )

2.I barely thought of it going into the battery as a loss before , because i would be using about 110% of the generators output at cruise

3.I wasnt mentioning the rotary for just its sheer size , but more so for the fact that its small but has a higher cc equivalency, for example the 13b (1.3l) mazda is said to be the displacement equivalent of a 3+ Liter piston motor , yet makes its power over the course of a wide (higher rpm) power band. this all saves weight and cabin room since in a series hybrid i could tuck the mighty mouse rotary ICE motor in the back of the plane behind a shroud , which is typically a wasted awkard dimensioned trunk-ish space in the plane'

4.One of the major benefits of a solo electric drive motor is that during the annual inspection which charges by the hour , if you have a simple EV setup there is drastically less inspection points and things they can hassle you over.
inspections can cost anywhere from $500-$3000 depending on how small and simple or vice versa it is

Now on to the Parallel talk, I regret having put "series" hybrid into my threads title because i'm fairly open to the use of parallel but i'm not quite getting its benefits and execution quite yet , You said -

Hi Dadeemster

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

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
Are you proposing that i put both the Ac emrax and a Small Ice on the Same propeller drivetrain? like two motors literally parallel to each other, under the hood linked to the propeller via some chain drive or some thing? Sounds efficient but also like alot of moving parts and hot motors in close proximity to each other ( i'm sure there are cooling solutions tho). Also if the Ice engine has to spin the prop and the ac motor/regenerator wont that just put more work on the ice motor thus affecting efficiency rates ? and how could you use ice engine and electric at the same time and also recharge ?

and can someone please elaborate the whole Charging a battery with a generator/ motor of some kind ?

i'd like to know the different methods routes to take on this for example

Ice engine -> DC generator -> DC to battery
Ice engine ->AC Emrax motor->??Controller, inverter, converter??->DC Battery

which is best for recharging a lithium battery ? i figured a regular ice engine /dc generator would lose the least efficiency since its not going ac->dc to charge the battery but instead going directly to the battery
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DaDeemster, the planes you mentioned are questionable for being right for the electric conversion, except one the Sonex. All have flown with low power plants, but two are very slick and clean requiring more power than the minimum stated for them to fly well. I have followed two different builder forums and nearly everyone flying now has installed the largest power plant available. I have followed both of the planes, the Sonerai II, and the Pulsar for many years and they are both great candidates for making a good cross country airplane but bad electric conversions. Fast slippery planes need a good deal of constant power to stay happy, something the modified Sonex does not need or the motor glider. They both have longer than needed wings, high aspect ratio for greater lift at a given speed resulting in a low drag, medium speed performance airplane. Motor glider airframes would be the best candidates for conversion since they have the ability to fly for some time without power, so the loss of electric power is not an immediate concern. If you keep the weights correct and CG in the design envelope, one of them should make a very good conversion. Match the engine output rating to the factory recommended gas engine output, and keep the battery volume within weight limits, and you can have a great self launching motor glider that can stay aloft for a long time, then power back home. That is the best of both worlds. not sure how good a cross country flyer it would make if that is your goal, but a fun local bird for sure. Good Luck! :)

Thanks for the input , i'm also in florida so i was kinda looking for a state / just outta state touring plane . i thought the pulsar might have been ok because mpg wise its very comparable to the sonex and the pulsars have been known to use the 65hp rotax 582 whereas the sonex flew with the 80hp aerovee engines minimum

the emrax has the same capabilities and then some over the rotax and it uses less Kw to produce the same amount amount of torque and a higher rpm range . Another benefit of the emrax is that the torque is there right off the 100rpm line whereas the bigger aerovees dont hit peak torque until 2400rpm

my thoughts were , if rotax is smaller then aerovee and emrax is equal to or in some ways better then the aerovee then powerband wise i should be better off then both right?

Also motorglider and xenos ftw but they are both hard as hell to find used . whereas you can get a regular sonex/sonerai/pulsar anyday of the week if you look hard enough . a xenos you'll have to build and will start costing corvette money by the time your even lookin at motor options.

If i could even get 250-300miles without landing i'd be happy because its not like with a car where you just pull over, your up in the sky lol.

also lets say a sonex uses 2 gal over 3 hours and goes 60miles (high lift low speed) and a pulsar used 2 gal over 2:30 hours and goes 60mph ( fast and slick) although the slick pulsar has more trouble staying aloft wouldnt it boil down to mpg because more time spent in the sky doesnt mean i went farther?
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do correct me if i'm wrong, but what i feel is different with a plane and a car/truck is that planes usually run at fairly constant rpm. so a series hybrid will work for an automotive platform where you get the engine to run constant, while the motor does the peaks etc. however for a plane, since you only have one up and down "cycle" each trip during take off and landing, you're running most of it at a fairly constant rpm and hence fairly constant fuel consumption.

The parallel hybrid sounds interesting, and I havent put much thought into that yet. but to me, maybe sticking to an ICE engine all the way may be the easiest option altogether.
when planes are going up and going down and have 80 or less hp they are lots of times are at full throttle, dumping as much gas as possible to keep the rpms barely climbin (if at all) through the torque range.
which keeps the plane at a decent rate of climb. but gas motors typically arent very efficient at max load/max acceleration, well atleast i didnt think so.

a few other things, I'd rather the plane be all electric then not at all, and seeing as how building a DIY electric plane with the capability of of loading up 2 people and flying a couple hours seems far from impossible ( some first attempt successes have already been completed and flown, i.e the links i had posted previously), i kinda figured that if people could get additional range just by bringing a generator onboard of thier EV's whether it be a tow along or a 10-15kw in the bed/trunk. then theres no reason why i shouldnt be able to get the same effect especially if i am dispersing the custom gen-set's current into a large enough pack (to avoid battery stress/swelling/electrical heat loss)

The rotary design lets me take a more Capable (more kw/compact/less weight) custom gen-set up with me and because of its benefits i could use the weight savings to bring up a small fuel cell with me

excerpt--"Based on Diamond Aircraft's HK36 Super Dimona, the E-Star's propeller is powered by Siemen's 70 kW electric motor. A small Wankel engine, supplied by Austro Engine, acts as a generator, supplying juice to the electric motor. Siemens says that fuel consumption is exceptional due to the combustion engine spinning at reduced RPM. An on-board battery pack, provided by EADS, gives the lightweight aircraft a boost in power during takeoffs and climbs. That battery pack is then recharged while cruising. During initial test flights, the DA36 E-Star was airborne for two hours."
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Also this --

The idea is valid, but what really makes series hybrid worth it, is not a small amount of batteries but a large amount. Those days with expensive and heavy NiMH cells are over. Now it makes economically and technically sense to have 30-50 km of full electric range, and all hybrids should be made plug-in.

This also has the point most people forget to mention: if you buy a larger battery pack, you can get more power out of cheaper low-power cells. For example, if you built a pack that can run 2 km electric, you would need to buy special power cells that are more expensive. If you build a 10x larger pack with the same cells, you get not only 20 km electric range (actually a bit more!) but also 10x higher output power (for higher speeds & acceleration). In practice, if you don't need all that power, you can then switch to a cheaper cell -- from so called "power cells" to so called "energy cell", latter of which is optimized for low weight and low cost (EV use). Larger pack = better battery efficiency, more power (= better acceleration at higher speeds), less need for cooling, and what goes without saying, more range.

Also, the energy recoverable from regenerative braking and the benefit running the ICE at optimum RPM (traditional points of having a hybrid drive with a small battery pack) is not so much; you may lose it in the series hybrid losses. The large battery pack changes the game by making your car a plug-in car. Then you mostly drive with electricity from the wall and only need gasoline for longer trips, and even then only for a part of the trip.

Expect to spend $2000-$3000 in lithium battery cells and you'll get decent electric range and power. You'll get this investment back in about 5 years in saved gas. A proper lithium pack lasts for at least 10 years.

Well, to be really usable, your range extender would need at least 10 kW (13 hp) of electrical power. With your truck, that would probably have you go at maybe 60-70 km/h on average with gasoline. With a largish battery, this would truly be average speed; for example, it would charge the batteries while you stop for a break. (You could also charge from a public charging point at the same time.)

So I guess a 125-250cc motorcycle engine ain't enough, unless it's only for emergencies and you are fine with a "limp mode" or extending the range only a bit. I think you need to go up to around 500cc or more. The engine and the generator will weigh more than 100 kg.

Most seem to be, but I'm also thinking about converting a pickup to a plug-in series hybrid with a 10..15 kW generator and full electric range of about 50 km.
that came from --
If anyone doubts the potential for application of series hybrids, wiki has pretty credible section on it -

The electric driving motor may run entirely fed by electricity from a large battery bank or via the generator turned by the internal combustion engine, or both. The battery bank may be charged by mains electricity reducing running costs as the range running under the electric motors only is extended. The vehicle conceptually resembles a Diesel-electric locomotive with the addition of large battery bank that may power the vehicle without the internal combustion engine running. The generator may simultaneously charge the battery bank and power the driving electric motor that moves the vehicle. The battery bank acts as an energy buffer. An advantage is that when the vehicle is stopped the combustion engine is switched off. When the vehicle moves it does so using the energy in the batteries. This reduces kerbside emissions greatly in cities and towns. Vehicles at traffic lights, or in slow moving stop start traffic need not be polluting when stationary.
In some arrangements when high levels of power are required, such as in vehicle acceleration, the electric driving motor draws electricity from both the batteries and the generator. With the Chevrolet Volt if the battery bank is depleted the vehicle may run entirely with electricity provided only from the generator. Some prototype vehicle designs such as the Volvo ReCharge and Ford F-Series pickup have electric motors in wheel hubs reducing the need for a differential saving weight, space and power being sapped by the differential. Series-hybrids can be also fitted with a supercapacitor or a flywheel to store regenerative braking energy, which can improve efficiency by clawing back energy that otherwise would be lost being dissipated via heat through the braking system.
Because a series-hybrid omits a mechanical link between the combustion engine and the wheels, the engine can be run at a constant and efficient rate even as the vehicle changes speed. The vehicle speed and engine speed are not necessarily in synchronization. The engine can thus maintain an efficiency closer to the theoretical limit of 37%, rather than the current average of 20%.[3] At low or mixed speeds this could result in ~50% increase in overall efficiency (19% vs 29%). The Lotus company has introduced an engine/generator set design that runs at two speeds, giving 15 kW of electrical power at 1,500 rpm and 35 kW at 3,500 rpm via the integrated electrical generator.[4]
As the requirements for the engine are not directly linked to vehicle speed, this gives greater scope for more efficient or alternative engine designs, such as a microturbine,[5] rotary Atkinson cycle engine or a linear combustion engine.[6]
General Motors in 1999 made the experimental EV1 series hybrid using a turbine generator set. The turbine weighed 220 lb (99.8 kg), measured 20 inches (50.8 cm) in diameter by 22 inches (55.9 cm) long and ran between 100,000 and 140,000 rpm. Fuel consumption was 60 mpg-US (3.9 L/100 km; 72 mpg-imp) to 100 mpg-US (2.4 L/100 km; 120 mpg-imp) in hybrid mode. Depending on the driving conditions, a highway range of more than 390 miles (627.6 km) was achieved. The results were highly successful, and would have promised to be more successful if a smaller microturbine was used, yet the EV1 project was dropped.
Two problems I see with using the planes you mentioned to copy the idea of Diamond: 1) is weight. The 13B motor and needed accessories to make it work right in the airplanes you suggest will be far too heavy. You need a much smaller engine like a 5 hp Briggs to be dedicated to a generator. Locating much of anything beyond 30 pounds in the tailboom of most any airplane, without significant ADDITIONAL weight added (now more to lift) to the nose will make the plane not only dangerous to fly, but possibly uncontrollable. Look at most designs, not much of anything besides the necessary controls are in the tail boom.
2) The planes you are talking about require almost their full rated horsepower to maintain level flight which is why you climb at such a low rate and high speed. I own a Grumman AA1 with the speed wing and can tell you from first hand experience that it is NOT a plane you want to lose power with. Both of the other planes mentioned cruise at 5 to 6 gallons an hour when you add the needed fuel to climb to any decent cruising altitude. Both of those other planes have very low payloads; one of the reasons so many are for sale though the owners won't admit it. Once they get in with full fuel, no one else can go unless they want to fly dangerously over weight.

I suggested the sail plane type platforms, which is what the Diamond electric is copying-theirs, because the loss of the engine power does not mean an emergency. You can still glide for some distance, maybe to another airport even, where as the short wing versions of what you suggest will glide a few short miles; everywhere besides Florida that means ditching or landing somewhere you don't want to! The Sonex is even the longer wing version V-Tail for minimum drag and max lift so that the electric engine does not work as hard to achieve and maintain lift.
thanks for the great food for thought, I've actually been looking at the motor-glider styles, mainly the xenos (long wing stretch sonex variant) and the europa xp with Long wings aftermarket option which would also give me the engine out safety margin and high L/D ratio, coupled with distance at altitude.
automatically from the the suggested gross take off weights you can subtract two major contributors of the weight and replace them with EV components-

The Installed Ice engine weight- Alternator, water pump, radiator, reduction drive, Oil, fuel tank, exhaust, intake/carb. Think about approx 240lbs-340lbs. Which i'd like to highlight are all "efficiency losses" as well and that most Engines are given a slightly overestimated Hp rating at the shaft and do not account for any "efficiency/ power losses"

Fuel weight- gas weighs 6.1lbs per gallon so say at max 17 gallon tank with a 2-3 gallon reserve = 112-122-132. Keeping in mind some planes have much larger tanks

total- 350(doubtful)-440(likely) +520(still likely)

I didnt account for CoG for flight and no doubt that throws me off but not the idea isnt broken .

When i said small small rotary i wasnt thinking mazda whatsoever (other people made rotarys) namelys sachs ,aixro, rotron and i think uavenginesltd never stopped making them they all weigh drastically less and can be found here

I'd also like to highlight a few points of the ev adaptation such as weight and the goal that i'm attempting to achieve .

batteries and management wiring/ Controllers would be the bulk at 380-500lb
emrax motor- 24lb
emrax generator- 24lbs
Sachs 303cc with Carb Mod -24lbs

with a better L/D ratio , its still HIGHLY plausible albeit maybe difficult on the builder/engineer's part

these lsa/motorgliders are capable of gliding for 30+ minutes after cutting out the motor and 30+ miles , provided i can cruise at 110-115 for an hour if i slow it down to motorsoaring high altitude speeds that its design is centered around aka 60-85 i will get better power consumption and would easily be able cover larger distances, take into account the following Plane manufacturers capability speculation on the subject back in 2007-08 which btw is 5+ year old technology and with no range extender

And i would only use the Custom high capacity generator for the trips out of state. and even then i would use probably only say 4-6 gallons for power generation on such a small motor and because almost the entirety of the trip will have been from plugin electricity all those efficiency numbers only apply to the time the generator spends in operation, local trips , and 100 dollar hamburgers become teeny burger bites

Other points : I dont car bout silence, just use creative baffles for exhaust design or figure out how to get small wankel under the hood
-i dont care about speed , i'd prefer overall distance/ motorsoaring/ relaxed touring characteristics

" simplicity and reliability of a small aero engine" - ICE motors have alot of things that can "Just Happen". I love them as much as any gearhead but they arent perfect and teardowns are a pain and cost plenty of money and time
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a europa xp w/out all ICE Components - 6500-14,000 dollars
a europa Complete with all ICE components- 23,000-60,000

this means if i bought one for 7500-10k ( Value based on 3 ads from last 2 days) then i'd have 10k-14k of spending room allotted before i hit the base price of whats on the market today
Don't get me wrong, I'm far from being anti electric or pro ICE for the sake of it. I just think that as a project at the moment it doesn't stack up. You're adding weight, cost and risk for no additional gain. You're effectively cramming 3 power plants (ICE plus 2x 3phase generator/motors), two energy sources and two high power inverters and a lot of bracketry to tie it all together in in place of one ICE... I know they can go pop unexpectedly but which of those two options sounds more likely to develop gremlins and realistically, which is going to be heavier :(

Personally speaking as as a glider pilot and an electronic engineer, given your stated goals I'd go for a nice standard 'off the shelf' self launching motorglider if it's the flying you're interested in. Second choice, with a much bigger budget and pretty well purely for the pleasure in the project and for quiet flight I'd go for an electric conversion on an existing self launching motorglider. Sell the ICE to pay for some bits. Seems like an expensive option to me but then I think the regulatory environment is a little different over there. A battery fire would be my main concern, pretty much every other powertrain failure in an SLMG you'll walk away from.
i typed a great response but i swear this thing signs me out and erases whatever i have written...

i pretty much said- when people make it sound like such a draggg of a swap it loses it's allure lol.
Its really just an electric vehicle with a compact high output onboard generator that weighs only 70lbs more then the vehicle would in its solely electric form

24lb engine+ 24 pound generator +11 pound controller + 11 pounds of misc.

and electric planes are already flying in this ballpark flight time wise, if not farther (this is info from 07-08,first attempts ) -

Since your a gliding pilot and engineer i was wondering what your thoughts were on the Xenos by sonex and the Europa Xp with Glider/Long Wings? they both get 40-45+mpg on their best "economy" behavior and both sport engine out landing abilities. They also seemingly stay in theme within your electric self launch motor glider params
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'd have range anxiety in a plane too :)

Sent from my iPhone using Tapatalk 2
regen would be nice for dipping in and out of different altitudes for sight seeing, you'd also be able to probably recharge enough when gliding out of high altitudes for a guaranteed 'power on' landing
------ -------
*battery density is only a minute part of the grand scheme of things when you account for the fact that the battery pack in this electric setup are almost the only item that is of significant weight

*this weight however is >5x the size of the Gasoline storage weight of an ICE setup of which the gasoline only takes up non majoritive proportion of the weight therefore a full gas tank only goes >4x the distance of a full ev pack

*Gas motors aren't always that efficient under a high torque load such as propellers especially when you take into account changing wind fronts, bad weather, takeoffs, acceleration, stall recovery, reduction drives,alternators and water pumps. Also there are inefficiencies associated with ICE motor propellers since they are many of the time designed in a way that makes a (efficiency) sacrifice to obtain a combination of climbing (acceleration) and cruising power since its peak operating power is not achieved across the entire power band.

*any energy from grid is over 4x cheaper then gas fuel with a growing margin of separation, also if plugged into a solar/biogas powered home the incentives for using plug in power increases many fold
-Cleanly fuel source

**Last but not least the Hi Power low weight generator, is supposed to be a RANGE EXTENDER not the main source upon which the vehicle flys . The MAIN POWER SOURCE is the energy from the grid. by supplementing the smallest amount of gas needed for the trip you can essentially fly Solely on Cheap grid power. medium and and long trips would still be feasible on small portions of fuel (think in terms of 0.25-3 gallons of NON-AVIATION FUEL$$).
the small generator engine would work together with a low drag electric high efficiency generator aka small axial flux Ac motor. and due to lack of moving high load parts attached to the motor like in typical ICE setups, it would make more usable power and therefore more output energy

Yeah i'm pretty sure the idea would work fine . i'm going to do it in car first , then plane trials thereafter.

i was wanting input on how to operate max regen abilities with ac motor. Or in other words how to use its exclusively as a generator, and are they reliable when used in that way.
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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
not even on a glider? -
No problem. Just give it the proper command and it will generate all day long reliably. I've used ACIM drives as generators often and know PM types will also do the job.
thanks, its a pretty crucial component.

what is the max voltage one could charge a 20-25kw battery pack with?

for instance can i use a 30+ hp motor and charge the pack at 15kw-20kw while using 28kw at the motor?
sorry i hate to site from another source but in response to pitch efficiency, this is what i meant about the electric motor advantage (User is Synergy)-

One principal reason for a possible efficiency increase in the case of a multibladed fan of smaller diameter, in the case you describe, is that we can load the blades in a manner more similar to the way our best wings are loaded, and let them behave more as an airscrew in terms of their AoA range over a flight speed range. Instead of a uniformly high blade loading, we can let high advance ratio and greater blade area lower the blade loading (and resulting induced drag) at high speeds, and yet overcome the higher resistance of large blade area at lower speeds by way of the available torque at the appropriate slow RPM called for by a lower airspeed.

This creates an "always flying" blade condition of higher blade CL at lower speeds, like our wings, rather than what often happens when we put 'high advance ratio blades' on an ICE: Often, root portions are fully stalled, creating negative L/D and demanding that we create and accept a smaller blade area in order to swing the prop. Props with that condition start off spinning at a higher RPM, then suddenly 'bite' as the forward airspeed unstalls the blades. Often this results in a brief lugging of the engine until the prop aerodynamic efficiency increase accelerates the aircraft, and the blade Angle of Attack moderates toward its higher L/D range thereafter.

The bandaid to provide the same result for an ICE is, of course, variable prop pitch. It adds complexity and weight, but it works well enough overall to overcome the fact that twisting a rigid blade causes totally non-optimum blade lift distributions and a loss of aerodynamic efficiency. A rigid blade can only be designed for one advance ratio, and getting each blade station to the correct AoA (or lift coefficient) for a new advance ratio would REQUIRE a local change in twist or camber, which is not a trivial engineering challenge.

Electric motors simply don't need any of this workaround complexity on their backs; they can turn faster to go faster and slower to go slower, like a servomotor driving a ballscrew. Trying it with a prop designed for an ICE doesn't work any better than using a rubber nut on a bolt: too much slip.

To get to where most people agree and follow this key strategy for electrically-driven props (efficient blades that slice and bite) is merely step one in a five or six step, whole-systems engineering process that leads to electric airplanes with nothing to be ashamed of. (On commercially available, off-the-shelf energy storage.) Another is motors of this caliber, which are only the beginning. Only when we adopt a zero-tolerance policy toward 'adding things' will we be on track to overcome today's battery limitations.

(BTW, I'm not sure you described the status quo torque/RPM relationships for an ICE correctly, and responders have replied accordingly with a degree of confusion/disagreement.)
A glider with the brakes out (regenerating via the prop in your case) drops like a stone to maintain airspeed, maybe 800'/minute as best I can estimate for what I fly without actually timing a descent. You may do a little better given air brakes also spoil the airflow but I'd not count on it.
thanks for the 'real world practicality' food for thought

Earlier on you mentioned the generator engine making more power because there isn't a high braking torque applied (propeller). Perhaps I misread you but if there's not a high braking torque applied it's not making high power, it's just freewheeling burning a little fuel to overcome internal friction and pumping losses, you get nothing for free.
-You did not misread me , i was just WRONG about the brake torque part lol i had some wires twisted

-Your planned generator is still driving the prop (or the pack) albeit indirectly through a drive system that's a lot heavier and lossier than a simple reduction belt drive.
correct me if im wrong but i dont think all of thats necessary, why not just find peak ICE torque. find light scooter/vehicle PMAC with compatible regen rpm range. Turn up its regen to max. then have 3 preset throttle positions , hi, mid ,lo . then for motorsoaring short distances (<140mi) use no generator and then use the modes incrementally as needed to extend range beyond that.

using the standard that electric vehicles get a rough equivalent of 4x the mpg(e) of a gas vehicle; if a gas plane hypermiling gets 55-60mpg at around 65-80 then a ev could get a equivalent of 220-240mpg using Grid electrcity.

even if my generator only put out an equivalent 40mpg to a ICE with a propellers 60mpg i would still be highly advantageous because i would have barely used the generator during the trip.

If i had a battery pack that will go 240miles total, if i use my a range extender at roughly 40mpg for 2 gallons aka 80 miles i would get an equivalent of 106mpg for my trip of 320miles. and thats if my generator at peak efficiency was a 2/3 the efficiency of an ICE motor with propeller,water pump,alternator, with and wind conditions

A direct/belt driven alternator sized (and likely re-wound) for your generating requirements will be the simplest way to implement a generator, the control is simpler than for PMDC, the high voltages/currents are all handled by simple diodes, the controller is a low power device.
do you think that would be simpler,more efficient,more flexible then a PMAC In generator mode?

edit- i decided a bit ago that a second emrax is overkill for the generator unit but a smaller a lighter axial flux could easily do the job such as a perm motor- or atleast something like it

Doing it in a car is far easier, the added weight doesn't contribute to the losses or structural problems in anything like the same way. The pulsed power delivery is quite different too allowing undersized, overloaded parts cooling time. When it lets the smoke out you can walk away from it :eek:
true that but then your not flying lol and you cant drive a car over water or mountains or anything besides roads and some off roads
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That is further than any battery powered airplane has traveled on a single charge to date, isn't it? And you would be carrying the extra weight of the engine/generator.
its do-able, more so now then before, your probably thinking of cars, Planes are more economical. Also the battery pack is derated a few kw to make way weight wise for to 50lb genset (*real world weight)

*six year Old Motors, controllers and battery tech got the non economically designed waiex variant with a BLDC motor, 17kw, battery got-

"Range: 87 mi (76 nmi; 140 km) - range is 164 miles (143 nmi; 244 km) with auxiliary battery option" , with potential for farther -

* Oh and this one did it this year, 230mile range -

*250miles electric version- 750mile hybrid version

-there are others but you guys can troll through the net
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To stand any chance of operating with a system efficiency above that of a standard ICE (especially considering the additional drag caused by the system weight) you're going to have to operate your generator ICE at its peak efficiency. So far as I'm aware and I could be wrong on this that'll be around the peak torque (not peak power) RPM at full throttle for a gasoline engine. You dump power into the electrical system in bursts then shut it down rather than throttling back. The generator set is the brake maintaining sweet-spot engine speed so it needs to be controlled to give constant power out. In reality not there may not be much control needed, it'll depend to some degree on the shape of the ICE torque curve and the rate at which efficiency rolls off away from peak torque. A wound to suit PM generator and diode rectifier may be adequate so long as there's over-voltage protection provided to prevent overcharging. If active control is needed to maintain good ICE efficiency an alternator will be simpler and less costly/weighty to control. I doubt there's much efficiency difference between these two generator sets so long as they're properly optimized.
I'm afraid you lost me with the mpg(e) bit and 4x performance increase for electric conversions. I presume this comes form 25% efficiency chemical-mechanical for a thrashed ICE (and presumed 100% for electric, more likely in the 70-80% bracket).
*to clarify, i meant economical efficiency. In which Electric Grid power is actually more then 4x as cost effective as aviation fuel-

A gallon of petrol can be interchanged for 4.5*2.8= 12.6kWH of motor work which after losses comes from ~15kWH of battery work from an oversized battery (avoiding extremes of charge) of ~18.7kWH
An aircraft that will go 45mi on a gallon of fuel will still only go around 45mi on 18.7kWH of battery or whatever equivalent mix of battery and fuel you choose as an energy source. Swapping to electrical drive is no way ever going to yield a 400% system efficiency increase.
I agree with you here but with a few variables i see differently

-if i'm understanding you right, are you saying that the motor is operating continous at 84% efficiency? Because the emrax operating field for this application is 94-96%.Which is about 13% better. By new numbers you'd need 13.125kWH rounded to 13.25kWH to go 45-50 mpg @ 95-100kts or 113mph(averaged) and using your 4/5 oversize figure you'd need a 16.5kHW battery to charge in route

I would use atleast a 25-7 so no overcharging size is needed, sacrificing a few kW hours of battery would save weight and allow for the custom genset with fuel storage accounted for

-Your equation also previously stated 15kWH of battery power per gas Gallon(e) Not 18.7 so everything past 15kWH (Actually 13.25kWH) would attribute to additional miles

-I'd also like to go back to the above underlined text, 95kts-100kts is not best fuel consumption speeds. Its the average continous speed on a trip . By slowing down you get better fuel consumption. Especially if your using electricity. allow me to elaborate with visual aid

-I'd Also like to Mention another benefit to a EM motor and their lack of certain ICE motor constraints via a conversational snippet from two forum users

"User1- Running it at 4100 rpm is very bad for the engine. Aim for 4800 min.

Have you done a flight test to check if she will fly a go round at max pitch?"

"User2-55% power equates to 4300rpm and 28 mp, I normally run at 4800 65% power with 29mp, 75% is at 5000 rpm with 31mp
Running at such low mp as you are will cause possible crankcase cracking and
Severe wear to the overload clutch so don’t do it...."

A large modern glider with an L/D ratio in the mid 30s only needs ~3kW input (net after losses) to sustain level flight (calculated from l/d, speed and mass) at nearly 100kph. A mere 10kWH of battery now gets you toward 200km range in still air and level flight. I think this may point toward where we'll see electric flight going until energy density improves significantly.
Once again at 27:1 your not doing bad -

heres an EPROP -
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I did take a short 'troll' on the interweb looking for electric airplane range/record/flight distance/etc and found a mentions of 200 but nothing of 240 or more like you said. And that engine generator would hinder your battery range, significantly. My point is you're pulling numbers out of the air which are unrealistic. I suspect 240 miles will be realized, and hybrid electric planes as well. But it isn't happening now.

BTW, I wasn't thinking cars. I was talking battery powered airplanes.

You want to build your own HEV airplane.........great. You ask for help here. I offered some. Good luck with it.
Did not mean to come off offensive whatsoever. i was just trying to be quick to respond to both of you guys. I thought you must have missed some of the links i posted (or atleast thought i posted)

to the the above part in boldi'm curious as to Why? Especially if its used only for On Demand supplementation

and to the part Underlined, Heres some stuff that might not be quickly found

sportsar epos-
Max. take-off weight 600 kg (1,322 lbs)
Empty weights (withouth battery containers) 275 kg (606 lbs)
Max. baggage weight 15 kg (33 lbs)
Weight of one battery container 53 kg (116 lbs)

No. of containers 2 + 2

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You said

So if the battery powered plane can only go 240 miles, and then you add the weight of an engine and generator, your range will be less on the batteries, right?

But I fail to see where any electric 'battery only' airplane has achieved 240 miles on a single charge. And it appears there has been some significant (read expensive) electric aircraft development lately. But I do not believe or see evidence that the parts and equipment exist today which you could buy and assemble to fly 240 miles on a single charge. And you used that as a premise in your logic.

It is like me saying: If my electric car can go 500 miles on a battery charge, ......

But it is just a pissing match. I think you use a lot of funny logic trying to convince us of something which doesn't really matter. Like I said; build your hybrid plane and enjoy it, no matter how far it travels.
sounds good to me, i'll take your opinion into account with a grain of salt, as you should mine. I came for objectivity and constructive criticism. It can be greatly beneficial from an educational point of view to truly re-examine plausible options and objectives. thanks for the critique, and who knows if its successful maybe youll see the the idea flying high. If it fails i'm sure the components will make for a hell of a EV car
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