Two motors? From X4

You should be able to use 2 motors, 2 ESCs and 2 batteries from the x4, at 160amps you would be pulling 7c on the 22mah bonkas. I would personally upgrade to 100amp ESCs so at 80amps its 80% of ESC rating and would go with HV 25mah batteries. This would provide longer run time, more thrust and not be up against specs. Also if you skip folding or feathering props, retractable CF beam it should be a really easy build.

I wouldn’t go with 25mah batteries as they might get you 5 seconds of cruising. I would probably go with 25Ah batteries. Lol

Ha. Good catch. Was referring to these:

Hi, I am interested in building an electric foot launch powered hand gliding unit similar to your e-help. I looked at the your files (thanks for open sourcing your design) and I am wondering if it is better to use MAD M30 at 14S or MAD M40 at 24S. Which option will give me more efficiency and more flight time if I use a total of 4 Bonka batteries.

The bigger prop and fewer number of props will almost always be more efficient. So if you want max efficiency, go with the 43kv M40 or even 40kv M50(doesn’t cost much more). The one downside is that you would be working with much higher voltages. So make sure you really know what your doing or have help from someone who knows what they are doing.

Hey, I was just reading this thread and saw you also got M40 for your own electric paramotor. There are 2 versions of this motor 43kv and 50kv. Which one is better to drive a 125 cm prop. How many batteries do you use and what is your setup? Thank you!

nice2care - PM me if you want to have a call to discuss. In the meantime below is some additional info.

For an ehelp (hang glider unit) both the M30 and M40 will work. I’m selling the prototype in the video to a buddy at the end of the season and have already purchased a M30 100kv for my next revision which will incorporate a lot of other changes. With that mentioned, I think the M40 is overkill and you will need to get a custom wound motor from MAD. Reidar typically uses a 34x12 prop with a 110 or 105 kv rewound hobby king motor. I’m using a 36x14 prop and upgrading to a folding hub which would increase to 37". I wouldn’t go much bigger than that as pfactor will kick in. I have an old LD explorer (mosquito clone) and it was very unpleasant to fly with the big prop, the prop will also hang lower and likely be in grass during launch even with skid to keep it from hitting the ground. If you go with 14s the 100kv M20 or M30 will work without being rewound as you can just go to a smaller prop, you’ll need to figure out what works. On my Hobby Wing 200amp ESC the over current protection often kicks in at 162 amps on the ground when running consistently and sometime in air but not as often so you may want to upgrade to a 250-300amp ESC. However at 14s you’ll get more watts from lower amps so the Hobby wing ESC may still work, don’t know if they are watt sensitive or just current limiting. Motor limits for the M20 is 175 amps and M30 is 195amps don’t recall the watt limits but they are definitely power (watt) limited.

I would recommend starting with the following:

What what thrust are you looking to get? Are you going for more power or less weight? What rpm do you want to swing the prop at? Do you have any battery limitations?

Not sure what nice2care is looking for. However my goal was lowest weight and one climb to 1,500ft. Which I basically achieved with 22lb all in weight and 2 battery system (got to 1,200 ft / 20min flight time). Below is table with test stand data and flight notes from that setup on Falcon 3. The thrust gauge wasn’t working for the MAD 20 motor tests. My conclusion is 8k-9k watts should be target power requirement assuming efficiency isn’t that much different for various setups which I wouldn’t expect.

Which 2 batteries where you using?

Current setup is with the Tattu HV 25ah. 22lbs all in including batteries (excluding harness).

Okay. My thought was having a single mad M40 50kv motor (6 lbs), 47-51 inch prop (~1 lb), 24s 300a capable BMS (1 lb), battery container (~ 2lbs), a light weight 18s esc (sub 1 lb), and 12 ish lbs of samsung q30 or equivalent li-ion batteries in an 18s configuration.

The total weight without a harness or cage of any sort it would be about 23 pounds. The battery could hold up to about 1.35Kw or roughly 20% more power than 2x Tattu hv 25ah batteries. Also the M40 should be more efficient than an M30.

There’s also about 6-7lbs for the mounting system, CF tube, CF plate, wires, etc. You’re setup will likely be 30lbs when done. Also 47-51 inch prop is very big for a hang glider, too big for me. I cut my keel off for a 34in prop but for a 50" you’ll want limiting lines connecting harness to glider so you don’t hit wing. I have these on my LD Explorer. Not sure li-ion batteries can handle the current required I think the C rating may be too low but others can chime in on that, also what 24s 300amp ESC do you plan to use? I’m guessing that’s not cheap. With that setup you are sacrificing handling for efficiency and adding 8 more pounds which is noticeable in flight. My goal is to climb to a thermal; on a good day you could launch when i nice cloud is near then thermal out for a long flight.

Anyway if you build it please share results and cost. My setup is about $2,500.

That guy never gained one foot hight above his launch level
he only had enough thrust to keep level flight and may be he was also helped by rising hot air from desert

Wow great information! cwallen93117 and Bob27 thank you very much. I don’t have much experience with electric motors and my understanding is very basic. I would like to build a foot launch powered hang gliding unit with at least 50 kg of thrust for an easy take off. I would like to have maximum efficiency so I can have more cruise time under power. I am not worried about the torque. I flew a mosquito harness and the torque did not bother me. I am thinking of a scalable solution so I can fly with either 2 or 4 batteries.

The advantage of using M30 is that I do have 2 Bonka (7S) batteries and I experimented with this voltage on my X4 unit. The disadvantage is that I have to run a smaller prop (34-36") and loose efficiency. With M40 I can probably drive a 49" prop but I am worried about the high voltage (24S) and the risk of fire with 4 Bonka (6S) batteries in series.

cwallen93117 I didn’t know Amazon sells Mad motors. Thanks for the suggestion. It looks like even M40 is available on Amazon.

What do you think about this configuration?

I suggest you figure out what ESC you plan to use prior to buying the motor prop etc. MAD doesn’t have an ESC for their M30 or M40 ESC. The MGM might work but haven’t tested. Good luck and keep us posted.

Do you think I can use this ESC for my project?

I would be very careful with that ESC. The MFG site is here: I have twin ESC from APS which is just a rebranded Flier and I’ve had issues so stopped using. You are strapping this stuff to your back I would buy the best quality you can.

This may work: need to check ERPM. Or this:

I would disagree…

I personally have a mad 24s 200a esc. They also make a 18s 300a esc