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Kyosho Inferno GT2 VE - Big-Block Edition
Hi all, I'd like to share my ongoing Kyosho GT2 build here. Already burnt up the Turnigy XK 5682 - 900kv motor within running 3 batteries, so currently looking for a good replacement to fit the big-block motor mount. Hope you like it, recommendations are very welcome. I am not aiming for any speed-run records, I'm just trying to build a hassle free ~100 mph set-up that can be ran for an entire pack without having the electronics melting down.
Set-up
The Looks: http://www.rctech.net/forum/members/...photo-2-28.jpg If Batman had a GT2 :) http://www.rctech.net/forum/members/...photo-1-28.jpg Under the Hood: http://www.rctech.net/forum/members/...photo-3-21.jpg http://www.rctech.net/forum/members/...photo-2-15.jpg Gearing a 900kv motor on 6S required some creativity... More info on that here: http://www.rc-monster.com/forum/showthread.php?t=32150 http://www.rctech.net/forum/members/...hoto-2-100.jpg Traxxas Revo spur on IG108 2-Speed Shaft (use with use the IG101 100mm Center/Front Driveshaft) http://www.rctech.net/forum/members/...photo-1-17.jpg First attempt at some DIY parts http://www.rctech.net/forum/members/...-photo-5-7.jpg Shortened Mamba XL2 with stronger heatsink clamping and bigger fan. CF bottom plate to help support the part that pushes the foamie on the brainboard. http://www.rctech.net/forum/members/...photo-4-11.jpg All mounted up http://www.rctech.net/forum/members/...photo-4-12.jpg Fans are 24V, wired through balance lead extension, so I can switch easily between 6S and 7S. This way also prevents the internal BEC of the XL2 from putting power on the fans when using the Castle link. Something that seems to cause potential issues: http://www.offroad-cult.org/Board/lo...40.html#289268. The UBEC is connected to the ESC battery leads, but it has a power switch, so it can be turned off when using the Castle link. With hindsight I should have just gotten a HV servo, and power it from the balance leads as well, in order to avoid the whole need of an external BEC. |
The Testing
Wet road test drive, skip to 3:24 for stupid-gearing/low-speed Mamba XL2 cogging test. [YOUTUBE]eQOeAabA_4o[/YOUTUBE] Weird thing is that the logs show peak motor RPM to be ~25k, which would translate to roughly 1100 kv @ ~100-120 A load. In the zoomed part in the third pic below, you can see the motor RPM going from 0-25k in 0.8 s; with current gearing, that 25k motor RPM corresponds to ~188 km/h wheel-speed... I know I spun the wheels a lot on the wet road, but that seems impossible. In the fourth pic below it seems like it almost takes a second for the ESC to lock commutation after throttle going through neutral. Then with smooth throttle build-up, according to the ESC, the motor revs up gradually from 0 to ~24600 RPM (with this gearing 185 km/h, 115 mph wheel-speed) in 3.3 seconds at 21.5 V, pulling 110 A. 24600 RPM / 21.5 V =1144 kv. Maybe the motor was on its way out already? http://www.rctech.net/forum/members/...first-test.jpg http://www.rctech.net/forum/members/...-test-zoom.jpg http://www.rctech.net/forum/members/...test-zoom2.jpg http://www.rctech.net/forum/members/...test-zoom3.jpg |
Cremation of the XK 5682 motor
I guess when Hobbyking is blowing off stuff for peanuts, there's probably a very good reason for it. In all fairness though, the motor was only rated for 106A, so maybe I just had it coming. Log partial with dry road testing shows ~50 A average, ~190 A peak. I thought I could get away with it with some good cooling, but the winding resistance appears just to be too high, causing them to heat up too quickly. On a positive note, it means I'll be looking for a nice replacement motor. RPM in log was unexpectedly high again. Footage: [youtube]PXOLQ-FTYfE[/youtube] http://www.rctech.net/forum/members/...photo-3-22.jpg http://www.rctech.net/forum/members/...-test3-all.jpg Also tried the new GRP slicks, and as Lizard already mentioned in his 1717 Slash thread, they're less grippy than the older treaded versions... The rubber already feels less sticky and it seems they wear down differently too, the slicks appear to stay smoother (pic below is both S5 compound, used on same surface, same conditions). Contacted GRP about it and here's the reply: Quote:
http://www.rctech.net/forum/members/...1-photo-15.jpg |
Search for new motor
Maybe I should have looked into it a bit earlier, but after burning up the Turnigy, I got my crayons out and made some graphs to get a better understanding of how much Power is actually required to obtain a certain speed, within a certain time, or distance; thought I’d share it here for later reference and for anyone interested. Basically there are 3 types of Forces at play when accelerating to a certain speed:
Power = Force * Velocity, so from these Forces, we can get an idea of the Power requirements. The first graph below shows the Force and Power components as function of speed for a 5 kg RC, with 30cmx15cm frontal area, accelerating at 10 m/s^2 (based on Lizard’s 1717 Slash: 0-150km/h in 4 seconds) through standard airmass. Drag coefficient, Cd, is guessed to be 0.35, same as the default in BrianG’s online calculator. Combined friction and rolling resistance coefficients are the biggest ‘fudge factor’ in the model. I chose them to have the Drag and friction/resistive Forces cross-over at ~50 km/h - just a shot from the hip, no idea how valid that is. The model is just a very simple and straightforward approximation, based on constant acceleration to top-speed (been way too long since I bothered with differential equations :D). In reality, the maximum traction Force the tires can put on the road is limited obviously, so the net longitudinal Force that is available for acceleration, will be limited and, in addition, will reduce with increasing speed due to the growing part of the velocity dependent components. Dashed lines in the graphs are the individual components (acceleration: a, Drag: D, friction and rolling resistance: f&r), solid cyan lines are the totals; solid magenta lines are totals minus acceleration, so representing the constant velocity Force and Power requirements. You can see how much the acceleration part actually contributes to the total Power requirements, and this model does not even take into account the (acceleration of) rotational masses (just needed a quick fix, might look at that later… well, probably not :D). Accelerating slower would lower Power demands, but running-space would become an issue then quickly. Even with 10 m/s^2 (about 1g), it takes about 100 m to accelerate from 0-160 km/h (100 mph). 0-200 km/h would take ~155 m… so accelerating slower would leave very little time for driving at top-speed (and getting a good reading of it out of a flimsy 1 Hz GPS logger to brag around with on the interwebz :D). http://www.rctech.net/forum/members/...86-powest1.jpg Next step is taking into account system efficiency, also a bit of a ‘fudge factor’. After some tweaking and comparison with results of BrianG’s calculator model, I put efficiency at 69%. Main difference with the scriptasylum model is that that model seems to levy the friction and rolling resistance into the "overall efficiency" (from battery input Power to usable output Power). If I put the friction and rolling resistance coefficients in my model on zero and take an overall efficiency of 63.7%, it seems to produce the same results as the online tool with electrical efficiency set to 85% and 4WD drive configuration - at least for the couple of speeds I checked, in the range that I’m interested in. The graph below shows the electrical Power and Current (@6S) requirements as function of speed. Based on these approximations, at 6S, it would take about 217 A to get the 5 kg example car (which happens to closely resemble my GT2 of course ;)) with 10 m/^2 to 160 km/h; sustaining that speed would only take 72 A. Continuing up to 200 km/h would take 315 A , plus/minus ~30 A for a kilo more or less and 135 A in steady state. Seems that beyond 160 km/h, things are becoming a bit more tricky. http://www.rctech.net/forum/members/...87-powest2.jpg Long story short: I guess it takes at least a 220-250A motor to be able to do 160 km/h (100 mph) comfortably and reliably with a low-profile 5 kg car on 6S, which also explains the premature death of my 106A Turnigy... good thing it was only 10 bucks. Feedback and motor recommendations are appreciated. Bear in mind the approximations above are based on a lot of simpliciations and assumptions, I have yet to check it with some logs I have of my 8ight-T to see whether it all makes sense :). |
Well, first off I would say you need to go up to 8s with the XL2 esc, or higher if you can find a controller to do it... Higher voltage means less amp draw for the same load.
Next, you want a motor that will turn at least 40k rpm, and preferably higher, like 60k. So you will need to go to a very well made (expensive) motor such as a Neu or whatever else is out there that is made well and balanced (4 poles design). A better motor will be more efficient and the higher rpm will allow for shallower gearing, and that will lower your amp load throughout the speed range. Your 900kv motor died due to overgearing... If you had put 12s through it may have survived (half the amp load) and your pinion could have been half the size thus startup load would be greatly reduced. You could probably do this with a Neu 1527 with kv around 1800kv on 8s will give around 50k rpm max and should have enough torque and mass to endure what you are throwing at it.... It would be nice to know what the horsepower (wattage) requirement would be to get to speed, and then to maintain speed. A that point it would be easy to determine the voltage needed with the amp capability of the battery and motor and esc that are available. But I know that higher voltage and more motor rpm range, and thus lower gearing is the way to go. |
Neu ftw
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Thanks for the feedback guys! Neu, or Lehner of course (go Europe! :)), sounds nice, maybe one day,... after selling one of my kidneys :). 6S use here was because the motor was only rated 6S (due to excellent rotor quality I quess). Also I'm a bit paranoid of frying my XL2 and want to give it some head-room, also under heavy breaking Voltage bumps (pdf alert). I do have a 7S pack already though, just no >6S charger yet. Might only be a marginal gain in Current reduction, but better than nothing.
You guys really think the kv is the problem? In the end what counts is the Power a motor is able to deliver right? Kv just determines over how wide of an RPM range that Power is spread out. I can't imagine a big fat Castle 2028-800kv, spinning below 30k RPM max, would not be able to pull even taller pinion/spur combos than what I used? I think main factor the motor died was just the poor quality. If you look at a snip out of one of the logs posted above, you can see that the load with that gearing, even at start-up, actually isn't all that high: 60 A average, 160 A max... should be peanuts for a proper motor, no? http://www.rctech.net/forum/members/...test3-snip.jpg I already have a 1527-1500kv size motor (TP4070 - "poor-man's Neu 1527") in my truggy. It's geared for ~91 mph no-load nominal and it needs very careful throttling and rolling starts to stay under 200 A (6S); it's pulling over 220 A frequently with that gearing (logs below), but it holds up well. I'm really impressed with the performance of that motor, but I more-or-less built the GT2 around the big-block motor mount, so it needs a 56 mm diameter motor :). TP56xx are likely candidates, but not sure yet about kv and size (weight). Would have been nice if Castle had a motor between 1717 and 2028 size. http://www.rc-monster.com/forum/show...06&postcount=8 http://www.rctech.net/forum/members/...150307-v-t.jpg http://www.rctech.net/forum/members/...27-35-expl.jpg |
Now that you had bad luck going with the low KV/RPM route maybe really try the opposite? The newer TPPowers seem to have higher RPM ratings, even the 5860 can go up to 50k. I'm wondering if those reinforced magnet holders the MBP-RC guy is talking about on his page are now being used again for all TP motors or only the MBP-RC versions. Maybe get one from him if you want to be on the safe side with high RPMs.
Oh, and there is a guy on a german forum who got a TP4070 2200KV and is running it on 6s with an XL2 in a Robitronic Hurricane. Seems to hold up so far but not too much info there about gearing, temps etc. |
Hmmm..., so here I was thinking I had it all figured out and wanting to prove the world my jumbo pinion was not a stupid idea... LOL... Maybe it is indeed better to go a bit higher kv...
A motor that spins twice as fast, needs to deliver only half of the Torque in order to put out the same mechanical Power (Torque*angular velocity of shaft). Torque is proportional to I/kv, in other words, Current is proportional to T*kv; so with half the Torque and double the kv, the Current actually stays the same. The difference however is that the the higher kv motor, has less windings / turns and thus lower copper resistance (which adds up more when it's a quality motor)... So from a copper (I^2*R) losses point of view, RPM should indeed be as high as possible. Non-copper (core and mechanical) losses however, increase with increasing RPM, so the big question is: where's the sweet-spot? Bruno actually has a 2200 kv TP5670 on sale, that needs a 400+ A ESC for full potential... so maybe not :). MBP has what seems to be an old (yellow 3 piece design) TP5840S-4Y, 1600kv (31 V max, 270 A, 715 g). There's also a TP5660-6D 1420 kv (old specs: 35V max, 285 A, 835 g) I'm considering. 36/36 gearing will probably be a bit too tight, but 36/40 and 40/40 light and cheap Revo gears will fit and give nice speed range: http://www.rctech.net/forum/members/...1-gt2-rev2.jpg Have to sleep on it :). |
What seems weird looking at all the specs is that D-winds seem to not only have higher Rm (D winds need sqrt(3) times more turns to get same kv as Y winds), but also higher Io (indicating higher magnetic losses), both indicating less efficiency, no?
Edit: Skrew it... just ordered the TP5660-6D 1420 kv (old specs: 50k RPM rotor, instead of 53k); 160 bucks shipped seemed like an ok deal at APS; the one at MPB would be 30 bucks more and from TP EU 40 bucks more (US still has low prices, but shipping and customs would ruin that). Now let's just hope I get the right one :D. Edit 2: Thought I'd just post this first myself... for the record, the 56 millimeters are not ribbed :). [youtube]qqaKi9NTzS4[/youtube] |
Great, can't wait to see how it goes. I really hope you get what you ordered, according to TPPowerEurope, the 6D is 1260kv.
But why no cooling fins version? You wanted to have something that is in stock? |
Sorry if it is a stupid question, but if you have a bigger pinion then spur, aren't you going away from the 1:1 ratio again?
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http://www.rctech.net/forum/members/...013-tp5660.jpg Bit of a gamble, but we'll see. It's no custom work, so if I get a different motor, I'll send it back. Quote:
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Hmm, you mean the last number is rotor length and the finned ones have shorter rotors? Now that would add another layer of confusion :)
Always thought they were the same because in the data tables they are listed both in the model no. column. I think same weight is just wrong, that would be a too unlikely coincidence that two motors with different cans and endbell designs etc. have exactly the same weight. |
Yeah, maybe their motor designations just don't make any sense...
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Ah, did not think of it that way, that sounds good indeed.
I hope the new motor serves you well! May I ask wich Eagle tree you use? And where did you buy it? And am I correct to see that you have a mill? If yes, May I ask wich one? Because I want one myself soo bad :) Keep up the good work! |
Thanks!
Got the EagleTree at a lucky eBay auction, was sold by a shop in Italy. It's the 150A version; I added 8AWG shunts to improve Current rating and lower Resistance (more info): http://www.rctech.net/forum/members/...photo-4-51.jpg It's not a real mill unfortunately. It's simple Lux/Wolfcraft drill stander with 2-axis coordinate table (no idea how to call those things :), see pic below). It can be used for very simple milling though, I used it to mill down the battery tray I bought to better fit my needs. Turns out that POM material is quite easy to work on; might try and make a new tray for my 8ight-T by myself. If you really want to make your own CNC mill, there's a thread on URC by Bill Delong about that. http://www.cn-gaming.net/feuerteufel2/gallux141213.JPG |
Thanks for the info man!
Is it the V3 version? Maybe CNC later, I like the hand crafted work mote somehow. Maybe to show to the older generation that there are kids out there that love to get dirty hands, and make nice things :) |
No, v4 even; not sure, but I think v4 has bigger memory for longer logging. Been wanting to get that nice 10 Hz GPS sensor for it, which should be big improvement over my 1 Hz bicycle logger, but too many other projects needing money more urgently :).
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Ah, that was a good deal then indeed!
Keep up the good work, thanks for all the info! |
Received the motor. Seems to be the correct one, even has new 2 piece can, so size-wise it's same as current TP5660s: 80 mm long, instead of the 92 mm of the old specs. Measured kv with the XL2 to be ~1500, so even slightly hotter than spec. Will do some more tests to get a bit of a feeling for timing vs no-load Current later.
Pics below show how much more copper the TP has over the Turnigy motor. Despite having same size and lighter (vented) can, the TP weighs ~70 g (9%) more. There's also a comparison pic of the motor wires, the cutted piece on the bullet connector is from the Turnigy, looks kinda poor compared to the TP's; I actually had to dremel-out the holes on my 6 mm bullets a bit to get the TP wires to fit. But, in all fairness, the TPs cost about twice as much as the Turnigy would have at regular price. Hope the TP can live up to the expectations raised by specs and appearance :). Still intrigued by the similarity of the appearance and specs of the Turnigy XK5682 and Leopard 5682. Would be interesting to see if anyone has some nude pics of the 56xx/58xx Leo motors. http://www.rctech.net/forum/members/...172-tp5660.jpg http://www.rctech.net/forum/members/...photo-2-29.jpg http://www.rctech.net/forum/members/...-vs-tp5660.jpg http://www.rctech.net/forum/members/...photo-3-23.jpg http://www.rctech.net/forum/members/...photo-4-16.jpg http://www.rctech.net/forum/members/...-vs-tp5660.jpg http://www.rctech.net/forum/members/...8-photo-16.jpg |
Did some simple no-load testing of the TP5660; used the XL2's datalogging only, which appears to have a bit too low of a Current resolution for accurate figures, but I was too lazy to solder TRX-to-XT150 adapters for my Power meter and you probably get the picture.
Seems those D-winds are pretty power-hungry compared to Y-winds indeed, with quite high no-load Currents. Compared to my TP4070 with identical kv, but Y-wind, I measured this TP5660 D-wind to have about 2.5 times higher no-load Current. Measurements seem to correlate more-or-less with the new TP5660 specs though (although I'm not sure what the reference Voltage is in those specs). First plot shows max throttle response @ 14.1 V, for 0, 2, 4, 6, 8, 10, 12, and 14 deg timing. Second plot shows some DIY step response with a 6S pack at storage Voltage, for 0 (left) and 5 deg (right) timing. Last pic shows numeric summary of the datalog plots, plus a rough plot of the relationship between the no-load Power and RPM. Interestingly, it seems to take more Power (I*V) to spin the motor with a certain RPM at 14.1 V than at 22.2 V. As I translated the differences in Io already to Power, they should be fully comparable, so can't make any sense of that yet... maybe the ESC is involved in these differences too? http://www.rctech.net/forum/members/...iming-test.jpg http://www.rctech.net/forum/members/...ming-test2.jpg http://www.rctech.net/forum/members/...ming-test3.jpg http://www.rctech.net/forum/members/...0-newspecs.jpg |
Seeing your interest in wires, recistance, winds etc I am thinking you should find a long outrunner and rewind that yourself?
The difference seems to be huge indeed, but I think that is what you pay for to, the material? Copper is expensive ( at least here in The Netherlands it is ) |
Great pics thanks!! What a massive motor, my god. I can confirm that y- an d- wind motors behave kind of different. And what I have read and what I have experienced is that they react differently regarding timing. My TP motor d-wind works best with 7,5 degree. I think aveox, Castle motors have only y-wind for a long time now (dunno if that's true).
With what timing are you running the TP's? |
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Alright, time to get some life in this again. Stumbled on the Basher BSR Rally / Team C GT8LE-RA's 42T spur gears on Hobbyking, and thought they might work as a nice cheap and lightweight pinion/spur combo.
Having seen Lizard's disappointing results with the TP5840 and the resulting philosophizing about how a theoretical max efficient ERPM would translate into lower preferred RPMs for 6-poles (aka, I might have chosen the wrong kv again :D), I got rid of the my cool-looking, but not so smart DIY CF motor spacer, so the motor-mount is mounted directly onto chassis for better heat transfer. Gap between motor and chassis is filled with thermal pad, which also nicely helps cushioning vibrations. As this will only be used on-road, I won't seal up the venting holes as I did with my TP4070. Still need to add some o-rings to the center-dogbone dirve-cups, as there's a bit too much vibration in those still, but getting close to driving again. http://www.rctech.net/forum/members/...gear-mount.jpg http://www.rctech.net/forum/members/...-photo-1-2.jpg http://www.rctech.net/forum/members/...-photo-4-3.jpg http://www.rctech.net/forum/members/...-photo-2-4.jpg http://www.rctech.net/forum/members/...-photo-1-4.jpg http://www.rctech.net/forum/members/...-photo-5-1.jpg http://www.rctech.net/forum/members/...-photo-1-5.jpg http://www.rctech.net/forum/members/...-photo-2-5.jpg http://www.rctech.net/forum/members/...gearing-v2.jpg |
Had a little test-drive today: motor power has evolved a bit faster than my driving skill and it was a very big switch to get used to after having mainly played low-speed off-road lately :D.
Ran 42/42 gearing for a no-load speed of 185 kph @ 3.7V/cell on 6S, based on measured 1510 kv. Wanted to run 2 6S packs and 1 7S pack, but had to stop halfway the second 6S pack, because the gears (both pinion and spur) came loose and got chewed-up a bit. Had some throttle glitches in the beginning, with sudden brake pulses while accelerating, which might have been a contributing factor to that, but I think all-in-all the tiny M3x6 screws holding the gears to the spur mounts are just too small. Have to see how I fix that. On the spur-side, I can add lock-nuts, but on the pinion-side there's not any space for that... to be continued... Anyway, the important part: managed to get it up to 160 kph; motor wasn't breaking a sweat: max temp I saw was 48°C @ 17°C ambient, but I was changing settings a lot and not driving continuously. When everything is dialed in and with some more space and practice, I will be able to push it harder and temps will obviously rise, but from what I can tell so far, I think this motor won't become the bottleneck and I will be killing my batteries before the motor. Looking at the log data, I think I never really reached steady-state speed (need a bit more space and guts for that); data shows peak RPM was about 29-30k. Taking into account the Voltage sag (from ~3.9 to 3.4 V/cell) in the data from the 160 kph run (see below), it means the motor was running at ~94% of it's no-load kv under ~150-160A load, I think that's pretty good performance, and I am a bit relieved I did not immediately run in to the 60k ERPM mother-of-all-efficiency-walls. I started with 4 degree timing (found some info from Neu on timing settings, although not sure whether 100% applicable to 56mm dia 6-poles: http://www.neumotors.com/NeuMotors/FAQs_%26_setup.html), but switched back to 0 after I experienced some glitches in throttle response, which I thought might caused by the timing; turned out it wasn't, but left the timing at 0 nevertheless, as it ran well and I already had all the speed I could handle. @ Lizard: what timing did you run on your TP5840? Maybe wrong timing could be a factor in your resluts with it? Having seen how my TP5660 roars, I can't imagine yours not being able to top the TP4070, unless it's faulty. What is a bit bothersome is the ripple Voltage under throttle ramp-up. I thought the amount of Current draw is what causes ripple, bit it seems it's more the combination of high draw, low duty-cycle... maybe I should practice ramping throttle up quicker, in order to get to higher duty-cycles faster, but then peak Currents will increase again, and there's only so much power the wheels can put on the road anyway before losing traction... so I'll also see if I can fit some more caps easily. Gave the 2015 GRP tires another try (S3 compound this time), but they really suck balls and caused many near-misses and very high blood-pressure, in a bad way :), even hit my new camera tripod again, skating over the asphalt... luckily no major damage, but driving with those tires on a narrow street, is more scary than fun. Doing burnouts until they started to melt helped a bit to increase stickiness, but as soon as they got cold again it was back to drifting. Hope they go back to 2014 compound next year, or introduce some S0s. Anyway, pics or it didn't happen: New personal record: http://www.rctech.net/forum/members/...-photo-2-6.jpg Whe needs a body when you can have THIS instead: http://www.rctech.net/forum/members/...-photo-1-6.jpg 160 kph run, with Torque Control on 5: http://www.rctech.net/forum/members/...tc5-160kmh.jpg 150 kph run, with TC on 4: http://www.rctech.net/forum/members/...tc4-150kmh.jpg Loose gears: http://www.rctech.net/forum/members/...-photo-3-6.jpg http://www.rctech.net/forum/members/...-photo-4-5.jpg Throttle glitches (sudden brake pulses out of nowhere...) http://www.rctech.net/forum/members/...ttle-noise.jpg Settings: http://www.rctech.net/forum/members/...2-settings.jpg Small video - not much but at least gives a bit of an impression of how it drives: [YOUTUBE]-u0wiBMkxmE[/YOUTUBE] Also realized I hadn't even bothered to check ESC temps: http://www.rctech.net/forum/members/...60kmh-full.jpg |
I had timing set to 'low' don't know how many degrees that is from tbe top of my head now, I think 5?
But are you sure it's looking good? I mean 48C at 17C ambient with a big fan on it and no hard driving is not that good or? Almost 70C for the ESC also looks too high. Somebody on the offroad-cult forum said he had good results with removing the silicone stuff and the fabric and replacing it with this: http://www.conrad.de/ce/de/product/1...-Kerafol-86600 Edit: Regarding the glitching: I have seen that on the XL2 too, but it was glitching in forward direction. Also something is weird with the ms values, it shows min 0.500 and max 2.500 sometimes, although your calibrated endpoints are around 1.000 and 2.000. Maybe an optical insulation thing like Vedder suggested for the VESC would help? |
Regarding the screws, why not try red loctite?
Looks like everything is steel, so you can heat it up when you need to loosen the screws? The previeus owner of my Muggy "glued" the pinion on the shaft with red loctite, and dunked the setscrew in it, but with a pencil flame it came lose pretty fast. |
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XL2 temps are on the high side indeed, and I'm wondering whether that's mainly caused by the Current draw, or whether the high ripple Voltage is a factor in that too. Completely forgot to pay attention to temp of the caps. Thanks for the info on the throttle glitching, didn't know it might be a common thing for the XL2. The glitches happen both forward and reverse, in the plot with the 150 kmh run there's three in forward direction, also exceeding what the Tx/Rx can put out as throttle range... Quote:
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Oh, yes sorry, I am used to "normal" steel pinions :)
Maybe CA glue will help a little? Why spend money when you have something laying around that works as well :) |
Time for a déjà vu... upon inspection, I noticed the shaft of my TP5660 is loose too... :(.
It's not as bad as with Lizard's TP4070, there's still no "rotational play", but the shaft moves forwards and backwards a couple of millimeters under pressure, while the rotor does not move. I can see the rotor is fixed to the shaft with two grub-screws. APS, the shop I got it from, tells me I can fix it myself with some epoxy and just tightening the grub-screws. Have to look at that in the weekend, but, because the motor does not have a removable front end-bell, my main concern is I'll be damaging or knocking out the front bearing with the motor shaft, when the rotor is sucked in while putting it back... Alternative would be shipping it back to UK and have APS do it. Seems evidence undermining my love for TP is piling up lately. Did you get your TP4070 apart already Lizard? |
What I do, is put the front end bell flat on your working space, and then grab the rotor with a good pare of pliers of vice grips and some rubber or foam to protect the shaft, en sink it in slowely.
Now that I read that again, no pun intended :) But wouldnt epoxy unbalance the rotor? |
Ok, thanks, I'll try; I just know that with the couple of motors I took apart and put together again in the past, I did not really manage to control the rotor once it sucked itself in, and this would be the biggest rotor I have worked on. Magnet drag is actually less than with the Turnigy 5682 though, so maybe there's less iron in the stator to make my job difficult.
I think he only meant a little layer of epoxy between shaft and rotor, like some do with locktite on shaft/pinion too, shouldn't upset the balance too much I think. |
Yes, I had that to with my NEU's en Plettenberg, but if you have some vice grips, that clamp good on the shaft, you have a lot of control.
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I was just thinking, what if you use button head screws or countersunk screws on the motor gear, with the head towards the motor.
And then get a locknut on the aluminium plate? But you probably already thought about that? |
Thanks Ruud! I'll try and fiddle around with it a bit to see what can be done. I did get one of these already: http://www.ebay.de/itm/151846972547?...%3AMEBIDX%3AIT, in order to run the Traxxas Revo gears as pinion on 8 mm shaft as an alternative. It's a nicely made adapter, design and finish looks more professional than the single-speed Traxxas gear adapter I got for my center-spool in the past.
It's been a while, but I finally had some time to disassemble the motor. What I found was rather disappointing though. The shaft was very poorly secured to the rotor (no proper retaining compound: used 'glue' was soft/sticky and not hardened) and the shaft seems to have been modified or used/intended previously for a different rotor/motor (shaft seems to be shorted too, in what appears to be a DIY-manner). In the pics below, you can see additional flat-spots have been made on the shaft to attach it to the rotor in this specific way, as if the shaft/rotor combo was originally intended for a longer motor can. These flat spots are poorly done and are very uneven (you can compare them to the factory-made flat spots in the pics), making them unsuitable for proper attachment of the rotor and, in addition, disturbing the balance of the shaft. During bench-testing I already noticed the motor vibrated more than what I'm used to with other motors; I didn't pay much attention to that at that point, but seeing the shaft now, it I think the additional flat spots have ruined the rotor balance. You can see ring-shaped wear marks on the shaft caused by fretting on the edges of the rotor, induced by movement of the loose shaft under vibrations (remember, I only ran the motor once). I'm still talking to the seller about how to deal with this; I cannot imagine the motor left the factory this way, that would be very poor quality work in my opinion, so it seems some sort of customization has been done, although not executed very professionally. Anyway, what do you guys make of this? http://www.rctech.net/forum/members/...-photo-1-9.jpg http://www.rctech.net/forum/members/...-photo-2-8.jpg http://www.rctech.net/forum/members/...-photo-3-9.jpg http://www.rctech.net/forum/members/...-photo-4-6.jpg |
Wow, that was really Modellbaupirat's work? I'm stunned. That guy has a good reputation in german boating forums, wonder where that reputation comes from after seeing this.
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No, my TP4070 was from MBP, this one was from same place you got your 5670 from...
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No Question! Send it back. This Motor will not last long.
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