Electric PPG - ONE motor project -

Hello , as anticipated we are not professional builders but mine background and the technology I can access is high standard thanks to my previous job ( for my luck I have many many friends worldwide). Back to your question, I know well the manufacturers and the fantastic products you mentioned they are excellent indeed more… I have no ambition to overcome them but my product has an advantage that they cannot offer and exactly the fact of being an open source project DiY .
My idea when tests ( hope corona virus leave early ) will be finished and published (we will build a dedicated WEB page) is to freely distribute the project for which want build himself, sell the individual pieces ready to assemble or sell the complete engine…

We are not professional builders and profit does not interest us … but we are interested in divulging our experiences to everyone as we love electric flight

keep in touch my friend



Ugh, that sucks, but not completely surprising. I poked a teensy whole in MAD’s offering, Single MAD motor, but your testing blows it wide open. So sorry about the wasted time and money.

I love your ambition in this project, and am looking forward to the results. Are you looking to create a self-launching PW5? Keeping weight down in an FES-style glider application is so much more important than in PPG, and so if the PW5 is your primary target I’m even more excited to see what the results will be.

P.S. One thing that makes LMT motors so good is that they use a press to compact the windings in order to cram more copper in. I don’t know if the claimed increase of packing factor of ~40% is true, but in any case it can only do good. I wonder how easily a DIY person could compact the coils? Maybe with vacuum instead of a hydraulic press?

You have the wrong specs for the mad m40 80kv

This says it should have 30 magnets

With the Lehner Torquestar, the copper fill level is actually slightly more than with industrial motors. compared to china rc motors, the difference is actually up to 40%! that is true. the advantage of the size can be kept somewhat smaller in diameter. the disadvantage of this is that the heat is difficult to get rid of. so i was trying to build an LMT -eppg with a water-cooled version. But it didn’t make any sense despite the high-end cooling system etc. for e-aircraft motors , the degree of filling is not the only decisive factor. in the picture you can see a system that is still one of the best in the world, even though the development is now 15 years old. the efficiency is over 90% when working with a well-adapted esc.

since enough air can pass through the coils, the cooling is very efficient. but also with other systems with a high degree of filling such as rotex, hacker, e-glider etc. that use the air centrifugal effect, the cooling works well because the copper constantly transports and distributes the heat.

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Hi Bob27 you right , unfortunately I was one of the or the first in Europe to buy M40 and specs was wrong this was strong points con convice PayPal to refound me…

Hello , do you have different view pics ? Thanks

Interesting to know. My instinct is that it’s better to avoid generating the heat than it is to try to remove it, but it sounds like you’ve got real-world experience and that beats hunches every time.

What do you see as the decisive factors in e-aircraft motors?

BTW, very nice looking motor. What is it?

you can download pics from the net. it is a part from a hpd 10. the hpd 10 and other versions have patent rights. http://www.ecolight.ch/Images/Flytec.pdf

Hello , my project started in early 2011 when I bought the firts PW-5. For a long time I was looking for a Silent OP or CLUB to transform into FES, as you know the Silent is very difficult to find and its price is out of the market. So I start on my PW, unfortunately the nose of thisglider is too low and it is not possible to lift it from the ground as there would be problems with the incidence of the wings.
In December 2011 I became GM and sent to Shanghai to establish the branch of my company, then I was also given responsibility for our branch in the Detroit area, at which point
no time available and I sell the PW to Polish friends. Arrived at the end of January 2020 I have the opportunity after 42 years of work to retire and dedicate myself to my passion, then I find another PW (D-2177) and I start again with the project.

New motor after bench test will be installed on a hang glider more safe then glider for tests.

Idea for PW is install two REMOVABLE motors on wings with foldable props similar but not the same of this: https://www.youtube.com/watch?v=cqUQfJMkd84

2011 my first PW-5 test :



What is the point of the big flat hub with no vents? Why not leave it fully open, for cooling ? The idea of trying to water cool something that drives a prop and sits in the wind is ridiculous - you’ve got all the cooling you need, right where you need it, all the time.

You mention magnet ratings, but no mention of the steel grade in use - that makes a huge difference.

Did you know you can double the flux of magnets by arranging them in a halbach array? The increased spacing would also do wonders to resolve heat issues.

Please be very careful about making assumptions about other people’s usage scenarios. Please also be very careful about making assumptions about how much heat you can dump into the free velocity stream. Thermal issues are some of the absolute hardest to solve when it comes to power elex, and if you go into a R&D project not knowing how you’re going to handle them you will either need to spend a lot of money or you’ll need to derate significantly.

There’s a reason why even jumbo-jets can only run full power for 60-180 seconds. It’s not because we think it’s fun to spend more time close to the ground.

PPG mean PPG. You don’t do water cooling for the same reason you don’t use a car engine. That’s common sense, not an “assumption”.

If you can’t dump your heat into the air on an motor driving a prop, you have made a mistake in your design of the motor. It really is that simple.

I get that this guy wants to make something “general” so it can be used elsewhere, but, there’s a reason we don’t use a car engine…

I’m not sure the value of arguing about this. Seeking a level of purity in an online community and imposing that as a litmus test seems counterproductive to the general interests. Anyone is welcome to fly and equip any way they want, laws of physics and limitations won’t change.

Ultimately, motor power output is limited by heat. No matter if it’s heat because of eddy currents, hysteresis, bearing drag, or winding losses, the maximum power we can push into that prop is limited by when the motor suffers thermal failure.

There’s a neat aspect to e-flight: the question of whether we can run at high power continuously isn’t really relevant if we don’t have enough battery to run for more than a few minutes. So spec’ing for continuous operation at high power is wasting money, efficiency, and adding mass.

Let me repeat that: if your battery-powered glider is capable of being cooled completely at max power then your design has left something valuable on the table.

That being said, leaving into a design phase anticipating that you will achieve thermal shutdown at the precise moment when batteries reach 20% SoC (or whatever min number you’d like to pick) is foolhardy. So you need some tools in your pocket to be able to help your design over the inevitable thermal hump.

One tool is to overspec the motor. It’s easy and is well-understood with graceful flight failure modes. But it’s not the only way.

The ONE style design offers a potentially interesting way to be more liberal with the motor spec and yet not risk project failure. Water cooling adds significant thermal capacity without adding much mass. Water outperforms copper, alu, and steel by 4-5x. The upshot is that 1kg of water can allow a motor to run at continuous output for 4-5x longer, before even considering the effect of air convection.

Furthermore, the MAD M40 style design offers vapor cooling as a trump card which we can play, knowing that we can solve the problem forever for what amounts to a teensy spray bottle of water. It might not be ideal, but it means we can experiment with smaller lighter motors and that opens the door to cheaper flight with longer fight times and softer landings.

Or are we somehow against lighter, higher performing systems?


I call BS. Put some numbers on the table. Cooling is very heavy math, but it sounds like you’re using an armchair here.

I recently found a nother motor that has the same type of cooling system as the MAD M40


I also started looking for all the things that where pointed out as low quality on the M40 motor.

On big concern for many people was the tack/ resin used to balance the motor. Being big on drones I looked at all the motors on the drones I have around. I found that every single one of my high quality motors include motors from from emax, DJI all are balanced with this exact resin. I then looked up some other motors, and I found that other top of the line motors such as hacker and t motor use it on many of their motors, so I no longer see it as unprofessional as the best in the industry do it.

Hello my friends happy new year from Italy.
Finally after many tests (not completely finished yet) I am back. Regarding the balance with the resin I will not go into the merits, but having worked worldwide 42 years in the 5-axis machine tool sector for the Aerospace / Defense sector, I would like to say that I have NEVER seen any motor or mechanical system balanced with the resin and this is not an opinion but a fact. In terms of cooling my motor, it is equipped with a liquid cooling system that has never been used until now as the performance required so far does not require it, but in the future it is not known and I preferred to foresee it. Now I am working on a new winding and segmented stator, my project will continue with the “closed” motor technology as the stress tests performed have given better results than the FEM calculation for this I continue on this path. In these days of complete lock down in Italy not being able to reach my hangar I thought of developing my own WEB site to promote the project if you want to visit [https://www.onemotor.Ltd] even if it is still under development. Thank you for all your welcome comments both positive and especially negative about my project. Your support is really appreciated!


Very cool project ITGlider! I will be following.

It’s interesting to think about where eppg will go. The two main components that matter are the motor and the batteries. The batteries are progressing rapidly from industry and we get to enjoy the benefits of that.

For motors I felt like we are at the mercy of industry as well, but the problem is that other than large drones, there is not as much pressure to improve mid-sized electric motors like ours. Motors with enough power and low enough kv to be useful for ppg are just barely there now. It seems like openppg had to work with Mad to make a motor specially for this purpose?

What I like about your project is: I didn’t think that making a brushless motor from scratch was within reach of hobbyists. Very cool. Will you share more on how you did the winding? What software did you use to do the FEM analysis?

Edit: now I’m down a youtube rabbit hole of diy motors. Cool stuff. https://www.youtube.com/watch?v=YsSm65DAcCg

Keep up the work. If you can get a 15kw continuous motor that is sub 4kg I might be interested in buying one from you for testing.

Hi Bob, nice to met you , 15Kw motor is under test , unfortunately due to Covid everything is late, I think anyway I can finish the tests by mid-February as soon as available I’ll contact you, in the meantime if you want please consider to register on my website www.ONEmotor.Ltd in order to have fast communication, Gianni from Italy

Hello, www.onemotor.ltd 15Kw continue 3.8Kg still in progress …
in the mean time take a look on the motor 3D

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