SP140 Max Continous Power

Power System
1

First time post. Thanks for any help.
I’m a 250 lb pilot flying at a field elevation of 5200 ft. My 4 stroke trike weights 255 lbs so with 5 gals of fuel I’m at 535 lbs. My engine produces 28 Hp at sea level but only 23 at takeoff with my elevation. I use about 20HP for level flight cruise. I fly a 37 Meter Gin Condor. I can fly at this altitude but performance is not stellar. Also, my measured thrust is about 160 lbs.

So I’m thinking of an SP140 with a light (30 Lb?) trike. With the large batteries it looks like my takeoff weight would be about 360 lbs. and I would have more power than my current set up. Sounds too good to be true?

The SP140 says it produces 25 Kw and 175 lbs of thrust. I’ve read that that is not a power setting you can do continuously due to battery overheating.

My questions are:

  1. What is the max continuous power (Kw) I can safely expect from an SP140?
  2. Given the comparison with my current trike, it looks like flying an SP140 with a light trike should give me a decent performance gain. (Using my current wing). If this is true I’m ready to pull the trigger. Am I missing something?

Thanks.

1 Like
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Where where you getting the 20hp cruise from? All your other numbers appear accurate, but 20hp for a cruise seems really high even for such a heavy rig. On the other hand, I have seen people fly with full speed bar at 45mph and using about 17 horsepower with less than 250 pounds all up, so it’s definitely possible.

3

Hello @deadwood, welcome to the Forum!

I have been flying the the SP140 with a light Trike (AirOne Unique Single) a couple of times now.

OpenPPG SP140 on AirOne i01
OpenPPG SP140 on AirOne i01922×1046 471 KB

OpenPPG SP140 on AirOne i02
OpenPPG SP140 on AirOne i021248×1134 797 KB

The real world weight of the SP140 including the large battery and Dudek harness - ready to fly, but without wing and rescue is 35,1 kg / around 77 lbs. The AirOne is 18 kg / 40 lbs and the Rescue adds another 2.5 kg / 5 lbs => 123 lbs + your wing + you is roughly your minimum take off weight.

There are trikes that have a few libs less. I did consider some of them, but took into consideration how much they have to absorb on a not so gentle landing.

The main challenge you are facing is the continues power draw from a single large SP140 battery. According to a post from Paul it is rated for up to 10 kW continues power draw (@Pdwhite Please do make this fact more visible by adding it to the manual :wink: - especially for the small battery with it’s 5kW rating). 10 kW does match the fact that the DALY BMS used in the battery is a 100A BMS.

Drawing more than 10 kW is OK for a short period of time, e.g. during take off.
The obvious problem here is that we don’t know how long “short” actually is. Some vendors even define max continues power draw as 180 seconds, which is ridiculous.

Your only way to be on the safe side is flying with two or more large batteries or another battery setup.
Please do not take the risk of overloading the components by flying at >15 kW all the time. Stuff might fail on you while smoking.

If you add another battery your flight time will also be more than the sum of two single batteries due to the fact that batteries can deliver more energy in total on a lower draw rate.
Just as an example take a look at “discharge engery” of the Samsung INR21700-40T 4000mAh measurements publicly visible at lygte-info.dk. Higher average draw results in less energy deliverable before hitting the low voltage threshold + less voltage sack due to less load per cell.
I am not sure what cells the SP140 is using. The effect is way worse for some other cells.

My flight time with the SP140 and the large battery and a 31sm Dudek Boson 31 is up to 26 minutes when being very gentle on the throttle.
Then the BMS cuts the connection, most probably due to the fact that one cell group hits the low voltage protection threshold.
This is clearly less than it should be.

As I can keep the altitude at around 5-6 kW (SP140 throttle values) with trimmers closed, I should have better flight times if my battery would be OK. I am currently waiting for a replacement battery, which should be in snail mail delivery at the moment.

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Additionally the motor is limited to about 10kW continuous itself, so additional batteries wouldn’t help much.

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My level flight cruise is 3200 RPM which, per the MFGs RPM to HP curve is 23.4 HP. Corrected for altitude (-1% for every 300 ft) that’s 19.4 HP

6

Nice trike set up I like it. Seems like lots of room for extra batteries.
Thanks for the help. because of the 10 kW limit it looks like I would be marginal at best, even with an extra battery.

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Since I have been flying e-trikes with a total mass of 170 to 230 kg for a few years now, I would recommend you to use a motor and controller that are specially designed for trike operation, as well as at least a 150 cm ( better 160 cm ) 3 blade propeller. if you use a setuo like the sp140, which was developed for foot launch, you will always have a poor level of efficiency with a trike. it would be like thinking of getting the same performance with a top 80 engine as with a moster 185. of course you can also fly trikes with the top 80. but it’s not as fun as with a moster 185. i fly a dudek boson 34 for xc flights . this enables good speed with very little motor power. an important point with the e-trike is a suitable wing. i think your gin condor is ok. for your projekt.

it is important to me to mention. the sp140 motor is well suited for eppg.

it is pure physics that you can only run a certain amount of current through the motor without the efficiency being low. Regardless of the brand of motor, the copper cross-section of the cables means that only a certain amount of electricity is available. therefore you have to have a higher consumption as with the trike, for example, choose the motor and esc correspondingly larger.

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@Bob27 I doubt this is correct.
I have been pushing 15-20kW (readings based on SP140 throttle display = no accurate measurement) for two minutes on takeoff. ​
Can you please provide more info on where that claim that the motor is limited is based on?
What exactly do you mean by “is limited”?
Limited as in physically not capable, or as in won’t survive the higher load for longer than XYZ minutes?

The manufacture of the MAD M50C35 PRO EEE suggests in his specs that the motor is not limited to 10 kW.

If this is wrong for real, than I prefer to learn this on the ground rather than in the air :sweat_smile:

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You can push the MAD M50 motor up to about 20kW real world output power for short periods of time, but if you hold much over 10kW for long periods of time, you risk overheating and damaging the motor. The real limitation of continuous power is the rate at which the motor can dissipate the heat.

Because of this, I’m interested in having MAD motors modify some of their M50 motors for me by adding some cooling fins onto the inside portion of the stators like they do on all their other M series motors and slightly modify a few other aspects of the motor for better cooling.

IMG_20200430_103725524~2
IMG_20200430_103725524~23120×4160 2.17 MB

If done right I think we could get a few more kW continuous output with minimal weight increase. It would definitely increase cost, but for my needs it would be well worth it.

1 Like
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Yes, I’m a little surprised that they advertise a 25 kW motor, which got me interested, but now I find out I can’t use more than 10 kW continuously, regardless of if its the motor or batteries or both as the limiting factor. Disappointing.

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Thanks Bratwurst. I’m very familiar piston and turbojet engines, but these electric ones are all new to me. I have a lot of learning to do. That’s why I was looking for a turn key system. Looks like this may not be it.
I was working with MGM to develop a system for me, but by the time they were done with it all they wanted 46,000 EUR!

12

I would like to point out that 3,200 rpm on your engine doesn’t necessarily translate to 19.4 horsepower. If the propeller is different in any way than that table was made with or if you have a different reduction, that number could be way off as it changes engine loading at that rpm. Additionally the engine running at 3,200rpm producing static thrust will be a higher horsepower number than 3,200rpm in-flight as it changes the engine loading.

There is still a chance that the sp140 would work great for you. You are shaving almost 200 pounds off your all up weight which will significantly reduce power consumption and I imagine a light weight trike for the sp140 would have significantly less drag than your current 250+ pound trike. In the end, 10kW may be more than enough power for you to fly around and I’m sure the 75% higher power to weight ratio of the sp140 would be really nice for your takeoffs and climb-outs.

If I would recommend talking to Paul personally as he knows this unit better than anyone else and see what he thinks.

13

Thanks for the explanation @Bob27 .

Maybe that depends a bit on where you use or test the motor. It might be a different story in sunny Texas than over here.
During my last flight the air on the ground was about 3° C / 37° F. I don’t think that this leaves the motor any chance to get hot.

Before flying with the SP140 we have been testing the MAD M50 with the VESC 100/250. In contrast to the ADP ESC the VESC supports a temperature sensor for the motor, which we installed into the motor. We have not been able to push even to 50° C / 122° F with a 140cm prop mounted to it (at less than 12kW). Besides the installed sensor we took external measurements which confirmed the sensor readings.

MAD M50 Temp Test
MAD M50 Temp Test912×796 222 KB

Of course the temp might increase significantly at 20kW.

If you have some measurement data at 15 or 20 kW load it would interesting to see it.

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Its shaft HP on the chart. Prop and reduction system has not changed.

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you can request a price list for all parts for an e-trike from geiger. the prices are very similar to those of hacker, or mgm / rotex for a plug an play setup. I deliberately do not put any prices in here because I am independent and install and fly hacker, rotex, mgm and geiger products myself. I am therefore neutral. all systems work very well.

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Dan, whats the field elevation where you are flying?
Did you get your battery problem fixed?

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My usual take off is at 180 m / 590 f MSL.
No, my battery problem is not fixed yet, but this should change soon. Getting stuff from A to B internationally takes quite some time at the moment.