The motor peaks around 3k rpm when loaded with a prop and the prop is limited to 140cm by the frame. Other than that, everything in the power train can handle about 35 horsepower for up to a few minutes at a time. Because of this it would be pretty hard to overload the motor and you could use almost any prop you feel like. Of course different props will have different efficiency characteristics so I would be careful with that, but it should handle almost any prop you throw at it.
Thanks for your great response Bob, however is this 40KV motor limited to 3000 rpm by programming parameters into the ESC or is it how it tends to be automatically limited to the 3k rpm when loaded with a prop ? By the way, I like the way you put it that it can handle any prop you throw at it
~3500k rpm is how fast the motor will spin without any load. So when you put a prop on the motor 3000 rpm will be the average fastest the motor can spin the prop. Because of this some small props could spin closer 3200 rpm with a full battery and the high pitch multi-blade props might be closer to 2750 rpm peak, but 3,000 rpm is just the rough peak rpm you will see at full battery with a typical prop.
Congratulations! am really impressed by so much performance. we in europe are certainly 10 years behind in eppg development. but that doesn’t matter, our weak projects are also enough to fly a little
Technology wise I think the E-ppg companies in europe are actually ahead of us in the US because they need to be. The big difference is that we can use higher voltage and lower current power systems. This means that we can draw about 60% more power while having the same heat build up as the european competition. So at 25kw power the motor in the sp140 is dealing with about the same heat as the motor in the Exomo at 15kw. The downside is that the higher voltage systems are more dangerous to build and work on.
this posting does not apply to bob.
Here is a note to everyone who is interested in electric drives:
There are motors that are designed for voltages of around 45 to 70 volts by adjusting the number of turns and the coils.
there are motors that are designed for voltages of around 80 to 120 volts by changing the number of turns and the winding of the coils.
the possible power throughput is almost identical for both with the same motor weight. the more volts, the smaller the possible amperage.
the efficiency is on a very similar level. plus / minus 1-2 percent. A high-voltage system has one small advantage.
The connection from the battery to the esc can be done with thinner cables.
a disadvantage of high-voltage systems is screeching in certain speed ranges, which is difficult to control even with adapted timming.
With both systems whether 60 V or 120 V it is the same that a wrong propeller can destroy the system in seconds.
there are only a few propellers that can be used for extremely loud high speed eppg systems above 2500 rpm. That is the reason why highly efficient quiet eppg have been using speeds below 2300 rpm for over 10 years.
if you do not use an esc that has a real active safety protection you should be extremely careful if you want to test other propellers and pay attention to the phase currents in the live telemetry on the pc.
or contact a professional and before you destroy your own system it is better to ask which propeller is suitable.
Thanks a lot for your very insightful comments, I am absolutely delighted to be learning so much out here.
One question however, you mentioned 2300 rpm as optimum, so why is the SP140 running at 3000 rpm’s , and further is it possible to control the motor rev’s by programming the ESC ? perhaps a dumb question
The idea is that they wanted more power for the sp140. So when using their big 3 blade prop, it should still cruise at the same 1800rpm range as all the other high efficiency E-ppg and it should climb at about the same rate as the other E-ppg at 2300rpm. The difference is that it has an extra ~60% power advantage over the competition. This means that when the E-ppg from Europe put their max 15kw into the prop it will only spin at about 2300rpm, but when the sp140 puts it’s 25+ kw power into the same prop, it can swing it in the 2800 rpm range(or smaller props at about 3000rpm). So at full throttle the sp140 will be very loud compared to other E-ppg, but at the same power level the noise will be very comparable.
The one downside to their high power system is that they are loosing about 3% efficient due to the higher motor kv. But due to the higher voltage, it is still nearly identical to the motor efficiency other E-ppg.
yes you can set the max rpm limmit with many esc.
A setup as an example is ideal: the motor and porpller are coordinated in such a way that 2350 rpm are possible at full throttle without limmit, briefly as long as the volts are high enough, but the current value should not overload the motor and esc, for example 11.5 kilowatts are it.
the esc is then set to a maximum of 2200 rpm. the esc and motor then have a large safety reserve and require around 10 kilowatts of input power. this power can be used for a few minutes at the start without having to worry about a little overheating.
the positive side effect is: the voltage from the battery goes down very far at the end, that is, the motor can no longer bring the full speed. but since a reserve is programmed by resetting the max rpm. the pilot does not feel this very much. in the end it will still have almost 2100 rpm available. that’s enough to fly over obstacles. Setting this type of setup has proven to be very effective for the general public. Professionals can also fly limmit without rpm if they handle the gas gently.
in this variant you can get the highest efficiency potential from a drive, since if there is no rpm limit the esc has fewer switching cycles at full throttle. if a setup is set in this way ds for example.
when starting from foot 25 kilowatts flow into the drive, the pilot has to be one of the best and fly an extremely small wing.
the battery has to be huge (approx. 30 kilograms minimum). therefore all real pilots fly the foot start with a maximum full throttle output of around 15 kilowatts.
with a few exceptions. there is the myth of 25 kilowatt eppg like many other myths that only exist on paper and some people dream of it on the pc.
I am learning so much of you blokes, and I am so impressed that you all have so much knowledge and experience to share with newbies like me. Good on ya man ! Good to hear that ESC can be programmed to limit motor rpm’s.
BTW I have been receiving some great advice from Bob27 as well and I have the same question for you, do you have a home build project for a throttle for the e ppg ? something that blokes like me with limited knowledge can put together ? cheers mate
Let’s be honest, bratwurst knows a lot more than I and has a ton more real world experience, so I would recommend getting whatever knowledge you can from him.
Retracted - thx.
Hey Austin, that claim of yours may be or maybe not true, however you have hands on experience and I highly value and respect that, so please do not stop showing the way, sharing and making flying affordable for all of us. thanks heaps mate
Hi all of you contributors, here are the specifications of the 3 blade prop manufactured by E props. used on the SP140 setup
Reference number T-J63L-140 PLUG - 3 diameter 140cm Electric engine 6M-6d50
price around 560 euros incl of VAT
Thanks. That looks like the prop that is on the Air Conception Nitro 200, correct?
It looks like the prop, but it is different one.
The T-J63L-140 has a higher pitch, even higher than the props used on the Tornado.
You will get different results if you mix them up. You probably get less thrust on the SP140 and reach a higher prop RPM if you uses the Nitro Prop.
Thanks for that explanation. So is there a US source that I can order the 3 prop? Want to make sure I get the correct one.
E-prop is making them, they dont have a ton of stock and production is backed up. We will have extra stock coming in this week. Ill add the props to the site so you can order there. I don’t think there is any one it the US that would stock the props we use. We have bi-blades in stock right now if you need, just message me but i am putting up them up on the site.
@Pdwhite Do you have any test results or experience to share with 2 blade vs. 3 blade prop?
The 3 blade version should give you a bit more thrust, but also drain a bit more energy.
Can you feel that additional trust subjectively?
Flying a full battery with a similar setup - any noticeable difference in battery live?
Efficiency between the two seems about the same to me. The biggest difference between the two is the thrust and vibrating. The tri-prop feels smoother and has about 20% more thrust. They seem to cruise at the same power for me.