Single MAD motor

A few things. First, you will need at least 3 of those batteries to handle the current required. that equates to a minimum of $2160 in batteries. There is less than $1300 worth of cells and bms systems in those packs, so if possible just make your own.

Also be really careful with those cheap ESC’s. Most of the time they cant handle weird fluctuations of current in these very large motors.

I must be missing something, according to the previous comments I understand flying an e-ppg takes “around 4.2 to 4.5 kilowatts” (I guess this is peak) so on a 72v battery pack it takes only 62A.
Which one of this kind pump-up ebike battery could handle.

Am I missing something? why would get in the trooubles of sending 200A in M40 motor to achieve 70kg of thurst when 20kg seems enough?

I’m new to e-ppg and only did a couple of flight with combustion ppg, but I built some other electrical stuff like eboat and ebikes and I am an electronic engineer with some spare time. So once I’m up to speed with your knowledge I would like to help to make a really afordable way to fly.

During takeoff and the initial climb most people want somewhere in the range of 100-130lb thrust which equates to something in the range of 12-15kw of real world power usage and they often need to hold it for minutes at a time. Also the cells being used in the battery pack(Panasonic nrc18650ga) don’t handle high currents well for very long without overheating and loosing efficiency. So in my opinion even 3 packs may be pushing it depending on your style of flight, location(elevation and terrain), and wing size.

The thing to realize about flight is that the boundary between the ground and the air is the most critical. Getting off the ground and to a safe height is a very challenging problem and continues to be a limiting factor. It’s a shame to have to spec an entire system around 1% of its operational envelope, but getting that wrong literally means a crash.

The upshot is that you want to climb hard and fast to an altitude at which you have breathing room. Once you’re there you can throttle back and enter cruise mode. But getting there is a slog, and it’s a long enough slog that you can’t assume peak power is different from steady-state power. By the time you’ve run your batteries/ESC/motors for 60-180 seconds, you’ve gotten pretty close to steady-state temps.

Yes I agree this is such a waste to dimension a system for 1/60of its use time! Wait… a very large discharge current is needed for a very short period of time… It sounds like a job for a supercapacitor! The supercapacitor will be used as an energy buffer when you need a current boost, and could be recharged in flight when you are not using the engine at full capacity.

To do a quick approximation:

  • @Bob27 said that we need full power of 15kW for 1 minute
  • let’s keep for the demonstration my basic ebike battery that can provide alone 4.5Kw
  • so the pre-charged supercapacitor needs to provide a boost of 10.5Kw for 1mn. this is J= 1000x10.5x60 = 630 KJ
    -A commercial super capacitor can hold 54 kJ/kg (15 Wh/kg https://en.wikipedia.org/wiki/Supercapacitor)
    630 KJ / 54KJ/Kg = 11Kg so You will need a 11kg today commercially available supercapacitor to do the job, too heavy but research in supercapacitor are going fast way faster that lipo battery capacity improvement.

But some research talk about energy density of 110 Wh/kg that should in our case be in a near future a super capacitor of about 1kg could help to reduce drastically the size/weight of the battery pack. No wonder why Tesla bought bought Maxwell a supercapacitor company for 218 Millions

If it helps the opinion of the MAD motor company, I just found that the SP140 is using a MAD M50 motor that’s not even in production yet.

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There is an M50 C35 PRO EEE on their homepage, but it is not linked under the paramotor category in the main menu (yet). Check: https://mad-motor.com/product/mad-m50c35/

Spec claims:

  • 91 kg max trust
  • 21 kW mx Power
  • 50-100V Voltage support
  • weight 4.2 kg

… and one picture on the MAD homepage can also be found on this page here :slight_smile:

Wow that took them a while to post it. I knew about the M50 a long time before even posting the previous comment. The one thing I didn’t know is that there is a 40kv version which should provide more usable rpm for a sub 60 inch prop.