Yeah, I don't really understand why they would use different rubber for the Revos and the Slicks in the first place and then also not provide any indication that they do... Italians... :D.

Oh, I actually meant whether the front wing downforce would be high enough to compress suspension to the point the chassis/ front skid plate would touch the road; I think that would a good recipe for crashes, so I really want to avoid that... Anyway, maybe I'm just overthinking and should just get it out and test a bit.

I think it's cool how you just drive with traffic, I don't really have the guts to do so, which does limit driving options a lot. Not so many empty, long, straight and smooth roads out there :).

@ ruud: yes, new toy! :) just getting started with it, some more info here.

Love those scorpion (XXL) buggies. The 1/10 looks like a sweet retro kit too.

That XXL is a tempting buggy, i've seen your movie on youtube, in a quest for the XXL, without knowing it was you.

An overpowered 1/10 2wd can be tricky, but this 1/7 looks like pure fun, it's like it's running in slomo. Very predictable so it seems.

Video isn't mine, it's not driving yet, needs some mods first :).

I just got a reply from GRP about the tire compounds:

'More lifetime' means harder compound, which equals less traction, right?

I just looked into my old mails, the last treaded ones I bought were from November 2014, not early 2015 as I first thought. If it is really true that the 2015 tyres all have the same compound then I guess I can ditch my Slash after I've gone through the last set I have from 2014 :(

Can't imagine we're the only ones being disappointed with the new compound, maybe they'll change it back next season. I did see something about ROAR and US market though, hope that was just about the wheels and not the compounds (don't what part would actually be regulated). In the meantime, maybe S1 comes close.

Dr.T: There was also somebody on the Traxxas forum who noticed the same with the slicks.


Finally, I received a package from Alienpower.

But somehow, the ESC is not repaired like Bruno told me before. Also, the motor was not touched although he told me he would replace a broken sensor. Instead, there is a new ESC in the package. But an un-sensored one. And the Program Box (that wasn't delivered when I bought the set) is still missing but there is another USB Adapter.

Definitely not recommended.

http://i54.photobucket.com/albums/g1...pseeggfjft.jpg






And my VESC has been repaired.

The FET Driver has been replaced, now it's working again. Benjamin already did a no-load test with my 1717, runs well according to him. He also wanted to do more tests under load, very cool. Why the driver failed is unclear, Benjamin said it could have been a short somewhere. Well, I'm pretty sure there was no short, but who knows, maybe I sprinkled some solder somehwere and didn't notice. Next time I'll definitely make sure that there are no shorts.


Here is a video of the repair :)

[youtube]O7vaW27kdLo[/youtube]

Crap of your bad experience with APS... What are gonna do? Get sensors off and try what it does sensorless? The extra poles should make it slightly smoother than a 4-pole under same roll-out.

I guess the more people complain, the more likely it is they'll make some changes again for next year. I think they update their compound almost yearly anyway, no?

Not sure yet. Maybe I'll just put it in the XO-1 and sell it. Now that my twin runs, I think I won't drive it very often anymore, it's annoying to find a perfect road. Then I could put the Trackstar (that didn't seem to like the Turnigy 5682, cogging like crazy) in the Savage, maybe it will work better with the 1515 in the Savage.

Yeah, I think they update it every year or almost every year. I'll write them a mail too :)

Put a TPPower 4070 3Y 1440kv in the Slash. Heatsinks are from Dr. Mad Thrust Hobbyking. 30t pinion and 36t spur should give 184kph (114mph) theoretically calculated with 3.7V per cell and (measured) 1550kv.

Tried it out today and reached 172kph (107mph) :D

[youtube]QtvF6btCq0c[/youtube]


Motor ran great, but not too long :(

During the first battery, suddenly the motor spooled up but the car wouldn't move. First thought broken slipper or loose pinion, but after looking more thoroughly, it's weird: The rotor can be turned with almost no resistance, there is no magnet drag at all (before, magnet drag was very strong) and there are grinding sounds. I don't think it's de-magnetized, checked motor temps ofen, never got higher than 52 celsius. Since the motor spooled up, but the pinion wouldn't spin, I think the only explanation is, that the rotor somehow came loose from the shaft?

http://i54.photobucket.com/albums/g1...psz3wzsprt.jpg
http://i54.photobucket.com/albums/g1...psnp1kpish.jpg
http://i54.photobucket.com/albums/g1...ps3owvex9q.jpg
http://i54.photobucket.com/albums/g1...psxwqxlyce.jpg

My rotor came loose from the shaft once. I used the hard core permanent locktight and it worked. I think the color was green

Linc used to always want to play that game with me.:oops:

Nice speed! Crap to hear about the rotor detaching... You got it directly from TP Europe? Let us know how they deal with your warranty claim please.

Can you tell if the 5 mm shaft is a turned down 8 mm, or 5 mm all the way through? Back looks 5 mm too, right? I'm thinking of getting another one soon too, but not sure wheter to get the 5 or 8 mm...

Those heatsinks fit nicely! I might have to steal that idea from you :).

Yeah, I've already mailed TPPower Europe, they answered they will forward my mail to one of their engineers.

The shaft seems to be 5mm all the way through (assuming it's not bigger diameter behind the bearings which probably wouldn't make sense). Not sure if that is good, atleast some Leopard 4092's had problems with vibrating shafts when spinning over 25k rpm or something.

But I think I remember somebody on URC saying that the 5mm versions actually have 8mm shafts, but turned down to 5mm. Maybe they changed something again with their motors? Man this is so annoying with those TPPower guys, you never know what you will get, probably they have no clue themselves what comes out of their factory ...

It is a total different motor, but my original Caste 1717 5mm shaft is turnded down from a 6mm, so the bearings etc use 6mm holes.
I think this is because they had a 6mm heli version, so they had a lot of rotors, and it was cheaper to turn the original ones down to 5mm then make a lot of 5mm ones, maybe that is the case with TP to?
That they had a lot of 6mm or 8mm rotors laying around, or already being made for other motors?

My 1717 XO-1 version is the same 6mm shaft turned down to 5mm. Hard to tell if the shaft diameter is for technical reasons (e.g. vibrations or whatever) or if it's just because for a given type of application there is a "defacto-standard" like 6mm for some Helis or 5mm for 1/8 scale cars.

I got an answer from TPPower China (TPPower Europe forwarded my mail to them) in the meantime, they asked me some infos about my setup which I gave them. We'll see ...

Next fail.

Tried the TPPower TP5840S 1600V on 6s geared for 184kph (same as with the TP4070) in the meantime. Motor weighs 765grams.

First test was with Torque Control set to 4.5 (like with the 1717 and TP4070). Didn't accelerate very well and maximum speed was just 135kph. Temps were around 50C after the pack. So obviously, Torque Control set way too low. What's weird, because the 4070, 1717 and 1515 required pretty similar values, all around 4 or 5. At first I thought it's because of different motor design or pole count and set it to 8.0 (Which is basically "off", with my other motors, everything above 6 becomes pretty much un-noticeable).

With that setting, acceleration in low and mid rpms was very good, lots of torque, alot more than the 1717 and 4070. Cogging from a standstill was also alot better when compared to the 1717 or the TP4070. But it ran hot pretty fast (72C after a few mins) and I could only reach 165kph, had the feeling torque diminishes faster with higher RPMs than with the 4070 or 1717. The 4070 got 172kph with the same gearing. Also the 10AWG battery cables and EC5 connectors got quite warm, never had that happen before. ESC was also over 60C after a few minutes, usually it never goes above 50C, even in summer after a full pack.

So it looks like that thing draws crazy amounts of current. Since a much higher torque control value was needed to get (nearly) the same topspeed, I think it is drawing those high currents mostly at high RPMs? I.e. it is inefficient at higher RPMs. Maybe another test with lots of hard acceleration but driving no faster than around 130kph will show if it's the RPMs that are causing this. If it stays cool then, I'd say 6-Poles are not for "higher" RPMs (that "losses get too high above 60k ERPM thing" Vedder talkes about on his Blog). Bummer, since I need around 35k RPM in the Slash because I can't gear taller.

Little bit offtopic, but I like how you say you "just reached 135" :)

Wow, what a puzzle... I can't believe (won't accept :D) our big motor theory being blown to pieces...

Can't make any sense out of it yet. Patrick explained that the TC value is the Voltage drop (Current x winding Resistance) across the motor. So a higher TC value allows a higher motor Voltage drop before limiting Current... not sure where this story is going yet...

Another thing Vedder said when talking about the power rating of my 4092: https://endless-sphere.com/forums/vi...esc&start=1000
The bold piece is what I don't really want to hear, given the no-load current of my TP5660 6D for instance is ~10A... What wind is your TP5840S, Y or D?

Like I told you, coincidentally, I'll gear my TP5660 for 184 kph no-load too, so will be very interesting to see how things compare. Just need to find a better spot to drive it.

On a positive note though, the TP4070 actually did remarkably well, performance wise. Hope they'll send you a new one with better shaft soon.

Its a Y-Wind. Regarding the bold text: Not sure if the load was too low? Considering that it reached only 165kph instead of 172kph with the same gearing, I'd say it was loaded enough?

Yeah, that comment was more in general and not specifically about your motor. The troubling part of that quote of Vedder is that it makes it seem that more powerful motors will just run hot anyway, even at lower loads. Maybe not as hot as an overgeared small motor, but still hot...

Your experience with the TP5640 still puzzles me, I think the difference between loaded RPM and unloaded RPM should indeed, like you said, indicate how 'loaded' the motor is, the bigger the load, the bigger the RPM drop... unless..., there's something else going on and it's not the motor that's the bottleneck, but the batteries that cannot provide the over-dimensioned amounts of juice the over-dimensioned motor needs to rev up to where it wants to go? There's some similarities with 0verkill's 4S mini 8ight that also does not go as fast as expected, based on gearing and motor alone, although his over-dimensioned motor (TP29-something) stays cool.

Re the braking we talked about earlier, I think the difference in acceleration and braking distance can be explained from the fact that all the forces (drag, rolling resistance, driveline friction) the motor has to battle during acceleration, are helping it during braking. Not sure how well it holds in practise, but theoretically, the motor Torque is proportional the the motor Current (x 1/kv). So if the motor shaft really would have to endure higher Torque at braking, that should somehow show in the Currents. My XL2 does not seem to log negative Currents, but my EagleTree does, and I've never seen my braking Currents go much past 40A in the 8ight-T set-up that pulls 200+A at acceleration. Now, I don't exactly understand how braking works, as I think braking Current can be divided between a regenerative part, sent back to the batteries (that part is measured by my logger), and a part that is just dissipated in the motor by the ESC shorting the motor windings (that part cannot be measured by my set-up). I think you and Vedder talked about that once, but I did not pay enough attention then to recall exactly :).

Edit:
Without a way ahead this would be too shit of a post :D... So, would be cool if you could find a way to log some stuff. Not sure if you want to use your Monster X on this, but seeing the Currents, ripple and Voltage sag, would definitely help solving this mystery :). Were you running a low-Voltage alarm that could have indicated major sag? Maybe hard to hear the beeps when high-revving metal gears pass by at over 100 mph though :D

Maybe it is a stupid thought of me, but if the batterys where the limiting factor, should it be accelerating more slowly, but once on speed, in will be no issue, to get that current?
I havent seen logs, and I don't know much about it, but isnt accelerating the highest draw part, and once at speed not so much, just like in 1:1 cars or horses pulling a car?
In the beginning you would have to pull hard, but once it rolls?

Yes, that is also my understanding. That's why my theory right now is that the motor must be pulling too much current at high RPMs (or maybe at all RPMs). I went 172kph with the same batteries and gearing with the TP4070. If the TP4070 can do 172 without stressing the batteries too much, why not the TP5840 then.




For me the question is, why does it draw so much current in the first place? Gearing was the same, the car is only about 100g heavier with that motor compared to the TP4070 and traction is limited so it shouldn't draw alot more power if I understand the underlying principles right.

Also I have read on boating forums, that the big 6-poles have much lower RPM drop under high load when compared to 40mm 4-poles. But maybe that comparison doesn't hold true for my case, because of the big length difference (5840s = shortest 58mm motor, 4070=longest 40mm motor).


I think in reality, rolling resistance and driveline friction is negligible, and drag becomes negligible below somewhere around 80kph :)


Like you say, the current is either not being logged or not being sent back to the batteries. But it is there (and the torque proportional to it).
Vedder said as far as he knows, hobby ESCs just sort of short the windings and have zero percent regen, but maybe that's only true for really simple/cheap hobby ESCs.

Regarding logging with the Monster X: No, I'll use it in the Kyosho buggy first, want to make sure it works reliably with a "normal" setup before I take it to the extremes. And I think logging won't help much, I have no baseline to compare with anyway. If everything get's hot and the batteries are drained very fast, I know without logging that it must be high currents. If the performance is not accordingly, it must be low efficiency :)

Yeah, crap... seems you guys are right and I'm trying too hard not to have to accept bigger might not always be better. There goes my theory of everything RC... did I say crap already?

The question for me is, is it really bigger motors, or is it just that I chose kv wrong for 6-poles?

Othello once ran a TP5850 600kv Y-Wind in his Losi 5t on 8s and it seemed to do quite well. Got a little warmer than the 2028, but considering that the Losi weighs 17kg and the TP is smaller than the Castle I guess that's okay. The guy that he got it from uses it on 10s normally and another knowledgeable guy on the offroad cult forum also runs them with those low kv values in large scale cars. 35k RPM with a 4-pole would be 23k RPM with a 6-pole. 600kv on 10s would be 22k RPM ...

I also remember a guy on the Traxxas forum some time ago who said the TPPowers he tried got hot in the XO-1 and he had better luck with the Leopard 5692, IIRC he also chose fairly high kv.

The 5670 also got fairly warm in the 3 minutes or so the Alienpower ESC lasted ...

Hi,

I think the 6Pole need lower kv than a 4Pole to work efficient. The Losi has much lower KV than you Motor. I mean the Castle 540 2Pole has more rpm than the 4Pole Version at the same Voltage. I have the some problem with the Tenshock on 4s. This Motor has a lot of torque but with the Xerun 150A definitively a lower rpm than a identical 4Pole Motor. I tested with three motors in the same car etc. The Tenshock has the best start power but on high rpm it get very hot and I misst 3k rpm.
Based on my experience I like a 4Pole Motor in a 1/8 scale car more.

Yeah, I have asked myself the same question about the Tenshocks some time ago. What I find weird is, that the Tenshocks are offered with about the same kv values (around 1800-2200) as other 4-pole motors. If they really get inefficient with higher RPMs (and they need the same electrical RPMs as 4-Poles to stay in their efficient RPM range), that would mean one has to use around 1000-1200kv on 6s with 6-pole motors. But Tenshock doesn't even offer motors in that kv range. Really weird, I mean, if it's true, Tenshock must know this (?) Or maybe they know this but offer the "wrong" kv anyway?

Here is a video with a short comparison between a Tenshock 2200kv and a 1515 2200kv both with same gearing in the same car, the Tenshock is 10 degrees hotter after the short run:
[youtube]NoKjoi3nr-o[/youtube]

Interesting stuff; if it is really the case that 6 poles need lower RPM to be efficient, I think it should somehow show in the no load Current, which is indicative of the non-copper losses - if those grow disproportionally beyond a certain (E)RPM, so should the no load Current.

Temperatures aside, I think it is still weird though that a 6 pole TP5840 apears to have a bigger RPM drop than a smaller 4 pole TP4070, under same load.

Ahh, so it can be tested by just spinning it to different rpms and logging the current?

Here is a comparison somebody did, the 6 poles have a quite high no-load current.
http://www.in-racing.de/forum/Vergle...02011-02_k.png

I think so. I asked Vedder once how much he thinks his 60k ERPM 'rule' can be generalized outside of the ~60mm 14 pole outrunners he has most experience with, but he did not really address that yet. Measuring the Io for different RPMs, should give some insight in beyond what (E)RPM range the part of the non-copper losses caused by the rapid EM switching becomes dominant. I posted some simple test I did on my TP5660 once in my GT2 thread, but without reference, it does not say so much, other than that the amount of no-load losses, compared to my TP4070, did worry me a bit already.

That table you psted is a very nice overview; it does show the motors with higher Io also have higher delta T (which I guess represents temperature increase after certain time running unloaded). It is hard though to translate these figures to loaded behavior, as then the (load dependent) copper losses (indicated by winding resistance) also start playing a role. My Turnigy motor for instance had fried windings, suggesting it was the load dependent losses that fried it, and not the RPM depentent losses.

So big challenge I think is finding the right balance between the copper losses (high at start-up, high load; and higher for low kv motors, because more turns means higher winding resistance) and non-copper losses (high at high (E?)RPM, low-load).

Yeah, since almost all of that energy is being converted to heat and not mechanical energy (the torque needed to keep the rotor spinning is just the torque to overcome the friction of the bearings), higher no-load current also means more heat.

The test was done by spinning the motors for 60 seconds, then waiting for 90 seconds, then taking the temperature.

Finally got my TP4070 back. Was a long story, at first they wanted to send me a new special 5mm rotor which is 8mm in the center and 5mm at the ends. But I didn't manage to get the old one out.

Then I sent back the motor to TPPowerEurope to have them change the rotor. Now I got the motor back with a 8mm rotor from end to end. Not sure why that is, didn't get an email or an explanation about that. The exchange took quite long because TPPower China forgot to include the correct bearings. And they wanted me to pay around 35$ for shipping.

So now I waited about 1 month and had to pay 35$ for shipping the rotor from TPPower China to TPPower Europe and around 15$ for shipping the motor from here to TPPower Europe. Not very cool considering that this is almost half the price of the motor.

But atleast, I should (hopefully) have a reliable motor now with that 8mm shaft from end to end.

So you had to pay because they forgot something?
That doesnt sound correct to me?

But I'll cross my fingers for you!

No, they wanted the money for shipping the rotor from china headquarters to TP Power europe in holland. The 2nd shipment for the forgotten bearings they apparently paid for by themselves.

Not my understanding of how warranty should be handled, considering that I bought the motor in europe. Communication was nice and polite from their side, but somehow a little weird and chaotic.

That's stupid they made you pay for their internal transportation. Could be a sign the TP EU and TP US distributors are not related as directly to the factory as name would suggest? Bruno put me into contact with the factory and at the moment things seem like they will turn out well with my warranty thing *knock on wood until everything's final*.

Hope the motor is good now and Godzilla Slash will finally be operational again, and stay that way. You can't go much faster though, or it'll be too hard for me to keep up :). You gonna run 8mm pinions or turn down shaft?

Yeah, I guess TPPower Europe is more a distributor than really part of TPPower.

Bruno told you the motor came like that from the factory?

Not sure on the shaft yet, I'm not very keen on hours of grinding. With the 32t 8mm bore Kershaw pinion I have I can get no-load speeds from 185kph to 207kph, I hope the 185kph gearing is going to be okay for running through a whole pack then I don't need to grind it down.

Yeah 185kph gearing sounds good, same as you ran before, no? Would be good if you can avoid the extra work and risk.

Yeah, at first I was sceptical too, but Bruno was right and TP (factory) took full responsibility for the state of my rotor, apologized and is handling it now, very satisfactory so far, but I'll share final conclusion when I actually have the stuff in my hands again :).

They really sent out such a motor? WTF. I mean, a worker having a bad day, okay, can happen. But this looks more like they re-used some old stuff and didn't do it right or in a hurry. Or while riding a rollercoaster or something, judging from the grinding work they did there.

Before I had 30/36 = 183.6kph, now I'm going to run 32/38 = 185.6 kph, close enough :) But I don't really like the heavy Kershaw pinion.

Lol, yeah, seems like it was done blind-folded... Looking at the mods done to the shaft, I think it might have been a rotor from the old 92mm length can 5660s, adjusted to fit the new 80mm cans; maybe it was a quick-and-dirty test sample that got mixed up with actual production stuff,... or maybe I'm just a bit naive thinking that :).

I'm very curious though on the retaining compound they normally use between rotor and shaft. In my bad rotor it looked like it was just some glue... I got the loctite 648 you suggested, seems exactly the right stuff for that purpose, but I'll probably only use that if my new rotor would detach again.