Converting a MONI motor glider to electric

[topspeed]

Munro claims the new Tesla battery will reduce the battery weight in half.

Well,.... He is wrong !

I kinda agree..it may be even heavier ?

 

[helno]

Munro claims the new Tesla battery will reduce the battery weight in half.

Half the empty weight of this aircraft is still to much to allow it to fly.

This is a conversion it is not a new build. The power system has to work with the weight and balance as is.

Luckily the original airframe had a large amount of ballast installed on the motor mount which means that this should be possible with no permanent airframe modifications

 

[mparker333]

I also have a moni that I plan to convert. Looked into it a few years ago but got sidetracked. Maybe something like this works for a motorglider like the moni.

3 Motors, 3 Motor Packs
100% Power 20.62 Kw 86% eff
Takeoff + Climb 10.00 min 5000' AGL
Climb Energy 1.33 KwHr
Energy left 4.66 Kwhr
Cruise Power 6.00 Kw 70 MPH
Cruise Duration 46.62 min
Distance 66.05666667 miles

I was thinking 75lbs of batteries, 20 lbs of motor (or (3) 6lb motors (Rotomax 150CC),
Belt drive to center prop shaft.
Think the Tesla battery packs are about 70Wh/lb but maybe a different design for flight would be lighter (different
requirements). I've gained about 20lbs since then, so gotta lose that (1.4KWh worth )

Never did finalize on what kind of prop though. Yes, the ground clearance limits the prop size. Thought about this one but it's probably way off.
Dia 39
Pitch 29
RPM 3000

Will be listening in to see how it goes. Best of luck!

 

[mparker333]

Nice motor (Emrax 188)! Weighs about the same as 3 of the rotomax 1500's, but it definitely has more than 3x the power.
How much do they cost? I'm cheap, think that's why I was thinking 3 big model airplane motors (about $500 each)

BTW, watch the weight and balance from the start. If you don't want to have too much trouble, plan on putting as much weight up front as the 2 cycle (25lb + 40lb ballast??). Since that motor only weights about 16lbs you should plan on at maybe 50lbs of batteries ahead of the firewall (is it still called that in an electric plane ). My gas tank is 6 gal so that's worth 36 lbs between your legs.
Where the rest goes is all up to W/B. I was planning on having about 85lbs of batteries because of cost (maybe $200/KWh)? However if I had more $ I would make room for "battery pods" to increase the flight time and place them appropriately. Think 85lbs would give you about 500-525 lb gross weight (with a 180lb pilot---which I will be again someday ). Going beyond that might be ok, but the g rating would go down (original rated for 6g? I forgot).

 

[helno]

Do you have a detailed W&B from the original builder? If you need a copy of the sheet to do the math I have the forms from the factory.

There is a lot of dead weight on the front end of a Moni since it was originally intended for a larger motor. The ballast in mine weighs more than the motor and double walled exhaust system.

 

[emotofreak]

I have a sweet electric package that would work perfect for you guys.

https://www.youtube.com/watch?v=rxfMx5OX_yk

 

[topspeed]

Aerolite looks very neat ultralite for electrics.

 

[mparker333]

Do have the W&B and all the paperwork. Figure about $5K for the batteries, motors, ....By the time I get to it there may be better options. Do think one tesla pack in front of the 'firewall' and one where the gas tank was. Dimensions, weight... look about right. Probably have to wait until I get the Glasair IIRG back in the air. Too many projects. That Aerolite looks cool, anybody knows what it uses? I'm more of a get up and go somewhere kind of flyer, but still nice just to get up there. Heard my boss on the radio leaving the company airport one time and asked him where he was going (as I was flying home). He said as soon as the wheels leave the ground he is there

 

[Solarsail]

The Emrax 188 PMSM at 23kW air cooled 29kW water cooled, I think would be the right motor for a glider / ultralight. I believe the price is about $3,500.

Here is an Emsiso H300 450V 300Acont inverter which I understand is a recent thing.

https://www.emdrive-mobility.com/portfolio/emdrive-h300/

There is also the Bamocar 700-80/160, which weighs only 4kg - which is half what other inverters weigh, but requires you to run at 5,000-6,000 RPM and go to 450V, to arrive at full power.

As for batteries, I suggest the Samsung 50E 5Ah 18.3Wh 21700. Rated at 2C cont. About 4 kg/kWh, and 55 cells/kWh. I figure with enclosure and BMS / controls, packs can be done at 4.25 kg/kWh. A 15kWh pack will be about 64kg (140 lb) and produce 30kW continuous power.

I am going with 14S modules, about 60V max each, which will be stringed in series and parallel to arrive at the right voltage and capacity. So if 240V max is needed, it will be 4 modules in series. I also plan to use the HV motor - not a fan of fat cables and connections getting hot. There is a reason why Nissan/Tesla are at 96S and Porche is at 140S.

 

[mparker333]

Think I'm going to go with the RotoMax 150 (2 of them). Just broke my motor/prop test stand. 30x12 prop, 6KW input (45V/133A), measured 52 lbs static thrust @ 5300 RPM. Then I cranked it up a bit, oops. 1/2" square steel tubing was fine, but the aluminum bracket holding one of the pullies bent, steel cable came off the track. Almost won the Darwin award New prop on order (30x12 and 32x12) for more testing. Think I will need to find a way to direct some of that airflow more through the motor. Those windings get pretty hot. Didn't get my final readings though, but pretty sure it was quite a bit more than 50 lbs (what I was looking for).

 

[mparker333]

Just adding some details (.pdf attachment) on my prop/motor combo test stand that I broke. A few mods (and new propellers) and will give it another go Will find out if the combo will run for 30-60 minutes at some reasonable power level (3-5 KW?). If so, will get serious and start on the retrofit plan (2 motors, cri-cri style, 2 Tesla battery packs, 2 controllers--all off the shelf), and custom control/display. No welding (a man has to know his limitations, that's one of mine ). Will need to learn something about fiberglass for the cowl mod (just the front 8" or so needs to change).

 

[kubark42]

Thanks for posting this. It's so great to be able to learn from others' progress, success and mistakes alike!

FYI to those who try the link, when it's copy/pasted there's an extra space which injects itself. The link is here: https://onedrive.live.com/?authkey=%21AJt1J3fSbH1zhPg&cid=1A41B552FACD70FE&id=1A41B552FACD70FE%2174176&parId=1A41B552FACD70FE%2154600&o=OneUp

 

[Giovanni LiCalsi]

Great topic! Love the Moni!
The new Tesla 4680 batteries will be salvageable from wrecked Tesla’s, by the end of 2022 and another battery manufacturer is planning to put a similar lithium battery into production, soon. Salvaged Tesla 4680 batteries should cost less than $100@KWr. That’s very affordable!
https://electrek.co/2021/02/25/tesla-4680-battery-cell-lg-korea-factory/
The new Tesla 4680 batteries use less space, are tab-less and are 16% more power dense. They develop less heat, as well.
The best way to get a proper size propeller is to increase height of the wheel struts, to be able to clear the larger spinning prop.
Keep in mind that solid-state batteries will be in the pipeline around 2025-6 and will reduce a lithium battery pack weight by at least 50% and require minimal BMS equipment, because they develop negligible heat. They can also be fast-charged and fast-discharged, without a burning passion!
Another industrial revolution, that will greatly affect aviation is Graphene carbon fiber, Graphene cloth and transparent Graphene/polycarbonate window glazing.
https://youtu.be/n82_NsFjj_8
Brushless motors have been going through new developments and are becoming much lighter and more efficient. It’s an exciting time to be designing an experimental aircraft!
I’m planning to build an updated version of the Facetmobile, using all of these new and upcoming materials and EV propulsion components.
Kind regards,
Giovanni

 

[mparker333]

Hi Giovanni,

I agree a bigger prop at the right RPM is ideal. However I'm presently planning on (2) motors, high reving props (~6K RPM) primarily for availability and cost.

Been a while since I posted, got busy at work....need to get a life Haven't rebuilt the fixture yet that I broke, but did acquire a Tesla 5.6KW battery pack (about $1K). I do need 2 so this spring will pick up another one and get serious. About 10Kwh@48V. Should be good to drive 2 RotoMax 150 motors. There are better choices out there, but not sure they are cost competitive yet. RotoMax+Prop+Controller is about $600. So, $1200 for the 'drivetrain', $2000 for the batteries, and probably $800 misc. Total ~$4K. Sold my unused 30HP 2 cycle (KFM 107 MAX) so that almost pays for the batteries. While a nice sheen of oil keeps everything protected I think I can do without it when I get the electric conversion up in the air. Should be a fun project. Was going to go off-the-shelf for the BMS and misc electronics, but can't help myself so that will be DIY. Probably will throw a Raspberry Pi in there (need to learn more about Linux) and a custom screen for monitoring/controlling the motors/batteries. More to come in the spring, it's a bit cold to be working in an unheated hangar (presently single digits, I'm a wimp .

 

[Giovanni LiCalsi]

Great plans!
Can’t wait to see it fly!
You may be able to use a Samsung tablet.
Good luck!