PARKJET MOTOR BENCH TESTING

Discussion in 'Electronics' started by e3_Scott, Jul 6, 2013.

  1. If you are not afraid of pulling the motor apart and taking out the shaft that's the cleanest way to cut it and not leave any debris in the motor. Or tape up the motor really good to seal it the use your cutting wheel to trim it down.

    You are running it on 3S?


    Cheers
    Jeff
     
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  2. Nakul

    Nakul Ace Pilot

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    Thanks Jeff, yes 3S for now :)
     
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  3. Nakul

    Nakul Ace Pilot

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    Funjet with Paidiss 3500kv 3s 25 - 50c lipo, Low passes :)

     
  4. :D :D :D :D that's awesome. .
     
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  5. Nakul

    Nakul Ace Pilot

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    :D
     
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  6. e3_Scott

    e3_Scott Top Gun

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    Hi Nakul -

    Well done, very fast on 3S:) What is the Mah capacity of the battery you are using? I would suggest the 25-50C is a bit low, even if you are using a 2200 Mah battery in my experience. From what I have seen from other fellow's testing, you might need something that can easily handle delivering 60+ amps on 3S depending on the prop you are using. Understandably, you have a buffer with the burst rating, but if the normal delivery capability of the battery is only about 55A for a 2200 for example (2.2 x 25C), you could be pushing the battery to it's max quite often. Additionally, as the battery runs down and the Mah are depleted, the ability of the battery to provide proper amps is depleted, but the motor continues to want to be fed lots of amps, putting even more strain on the battery.

    I know from experience relying too heavily on the burst rating too often will shorten a battery's life very quickly:oops: I found that with the really high performance motors, it was always safest for me to have 15-20% amp overhead for what my motor/prop combo requires, regardless of the burst rating. The burst rating adds in a bit of safety buffer, but not something I have found that is safe to rely on all the time unless I want to replace my batteries far more regularly.o_O

    Well done, your plane really covers real estate in a hurry:cool:

    Cheers,

    Scott
     
  7. Thanks to Dave I did learn that the mah works with the C rating to calculate the amp discharge rate. Probably the reason for a few bad batteries from pushing the burst rate to often. ;)
     
  8. Nakul

    Nakul Ace Pilot

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    Hey Scott, good to hear from you.. Yeah it was quite fast and also my jet weighs around 420 grams with this new motor and all electronics without battery, so weight to thrust ratio must be crazy. The problem i face now is to land this funjet, it glides forever and comes in really hot, should try flaps maybe. The battery i'm using are Gens Ace 1550mah 25C. iknow the C rating is quite low. got 2 of these, have also got 2200 wolfpack batteries (seems like a local brand of a famous rc store here) but they do not deliver enough juice for these motors. i have ordered 4 new batteries as my sister is in the states at the moment and she will bring them back for me, surprisingly since a year or so Hobbyking stopped delivering Lipos to India completely, hence its next to impossible to buy zippy/turnigy lipos here locally, the only ones available are Gens Ace & Tatu which also come in very limited variety in terms of C rating and at 2 - 3x the cost :( Anyways ill have my hands on 4 new batteries by 10th feb + some master airscrew props, and loads of other goodies that i cant buy or get shipped here. Have ordered Turnigy 40C & nanotech 35 - 70 C batteries, all 2200. In the meantime im also looking for 60C rating batteries if i can buy here locally. Only recently i got into this speed flying and hence i need to get totally different set of batteries as you mentioned, right now im just making use of what i have available.

    In short will i be good with the new 40C & 35-70 C batteries with Paidiss and Ntm 3000kv motor ? if not which one do you recommend ?

    Let me know and as always thanks for your input. Having a blast with this motor right now and my jet bounced 3 times upon landing last 3 flights, minor repairs on the nose and im good to go. :)

    Also happy new year everyone here :D
    N
     
  9. By Dave's explanation of how to calculate the batteries your's have a constant discharge rate at 38.75A . Most of my batteries are 40C 2200mah which gives me 88A, I just ordered some new ones, 3S & 4S all 60C now.
     
  10. Nakul

    Nakul Ace Pilot

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    ok noted, thanks.
     
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  11. e3_Scott

    e3_Scott Top Gun

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    Hi Nakul -

    You should be OK, but not knowing exactly how many amps your motor and prop combo are going to draw, I can't say for sure.

    While you will have theoretically 88A (for the 40C 2200) and 77A (for the 35C 2200) when they are freshly charged, as you take power out of them, I think it makes sense that the equation changes. I run my 2200 batteries to about 3.7V per cell on each flight and after monitoring them closely, I end up with about 950 Mah remaining after a flight needing between 12-1300 Mah to recharge them.

    So if towards the end of the flight my "tank" is down to .95A times 40C, the battery may only be able to deliver 38A which is why with the bigger motors you really experience that reduction in power late in the flight. This is fine for the smaller 2212 2200 and even the 2212 2700 Kv motors, but as you take the big step up to the more powerful motors, I think you have to be more cautious, especially if it is so difficult for you to get suitable batteries at a reasonable price.

    I recently wrote a couple of articles on the NAMC blog summarizing the techniques that I use to maximize my battery life and my theories now on choosing the batteries to suit my current favorite power setups. I am running some 2200 3S that are over 3 yrs old and although they are tired, they still work really well for the lower power motors.

    Article 1 - essentially all the mistakes I made early on:oops:

    Article 2 - lessons learned and techniques I have been using for the last 3 years. These theories may differ from the mainstream, I don't know, but they have all worked very well for me and I fly a lot and put a lot of cycles on my batteries.

    Good luck:)

    Cheers,

    Scott
     
  12. Nakul

    Nakul Ace Pilot

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    Going through your articles now thank you, i found this test video of the paidiss 3500kv motor, he tested it on 3s + 4s and the numbers are pretty good,
    3s 2200 40C - 5x5Tgs - 1260 g thrust - 68A - 755 W
    4s 2700 60C - 4.5x4.5 - 1650g thrust 77A - 1142 W

     
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  13. I have a few of those little 5" and 4" props and tried them and I don't think the speed was anywhere near what it does with a 6X3 prop. probably safer for the motor though. ;)
     
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  14. Nakul

    Nakul Ace Pilot

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    Ok noted again. i only tried with 6x4 prop so far, this weekend im going to try with 5.5x5.5 4.74x4.75 & 5.5x4.3 speed props mostly apc styles, lets see what happens! I guess this is the fun part of trying out new engines :p
     
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  15. Nakul

    Nakul Ace Pilot

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    Really nice articles! Glad i've been already following most of your tips in there. I always balance charge at 1C and store them at storage voltage, i use the imax b6ac v2 which does the job really well for charging, since i have limited batteries the moment i charge them at the field as well but at 1c only. i think 9 - 10 months in they are doing fine and no sign of puffing. Next job is to collect some good 40C+ rated batteries :))
     
  16. Nakul

    Nakul Ace Pilot

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    Hey @e3_Scott & @Wildthing,

    Been wanting to try 4s set up on ntm 2836 3000Kv.
    As i am not sure if i want to seriously get into 4s this will be more like a trial kinda thing, will def order a good 75c + rating 4s battery, the question is will it be good enough with this esc ? I have been using Hobbywing skywalker 40A & 50A esc's and they work flawless. Today i tried the paidiss 3500kv with 50A esc and 4s 75c battery and the esc and motor did get very hot, prop was 5.5x4.3 speed prop apc style. I will try 4.75x4.75 next, so planning to get the skywalker 80A esc, it has burst rate of 100A for 10sec, will this be good enough to use with ntm 3000 kv on 4s ?

    Product link: http://www.banggood.com/Hobbywing-S...C-For-RC-Airplane-p-1039600.html?rmmds=search
     
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  17. Hi Nakul
    I run a TGS 6X3 prop using the 4S battery not sure how that would compare to the 5.5x4.3 you used. 50A esc is ok on 3S and even then I usually use a 60A one but on 4S I put in an 80A esc. If I remember right (NTM 3000KV) on quick WOT throttle it would pull around 95A and about 1350 watts, so after some quick burst and speed runs you have to give it a few cool down laps. The Paidiss motor pulls just about the same but doesn't seem to stand up to as much punishment like the NTM.
     
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  18. I did play a bit measuring some motor data using different props on the NTM 3000 motor but it was before I had a thrust stand so it was just amps & watts. I didn't do the same for the Paidiss motor, on 3S the Paidiss has and seems very reliable plus great speed out of it using the 6X3 prop. With a 6X4 it does get somewhat hot so back to cool down laps. :D For the Paidiss using 4S you could try a 4.7x4.25 APC prop, on 4S with the NTM it dropped about 100 watts and 10 amps compared to the 6X3 prop .
     
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  19. Nakul

    Nakul Ace Pilot

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    @Wildthing thanks a lot!
    will order the 80A esc to be on the safer side as the peak burst rating is 100A. This is how i usually fly 2 WOT passes and later 2 slow glides, let the motor rest till i plan the next low pass haha Also thinking better to have 80A esc to later try the 4s + the esc for maybe an EDF project? Single edf, maybe one of shumates super bandit edf parkjets or anything like that.. i like to go slowly one step at a time :)
    Yes Paidiss is quite reliable on 3s, i used it with apc 6x4 and 50A esc, motor was barely warm and everything was running cool with great performance, i tried the same with 5.5 x 5.5 speed prop, worked great, with 4s everything got super hot but we did only 2 rounds with no WOT. just as a test, which clearly shows 4s is no go on the paidiss. But i hope NTM can handle the punishment :D Today something really strange happened, the paidiss motor's x motor mount broke at 2 spots and the motor got disconnected from the firewall and was hanging on 2 wires :O :( Luckly my funjet glided very smoothly and i could land it with only a minor scratch on the motor + the prop broke. :/

    Planning to get the tatu 4s 1800 mah 45 - 90 C battery for the NTM. 90 burst rate they say, will it be enough or i should go for higher c rating ? limited options here :/
     
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  20. Just lately I have had 2 mounts break also, I use some blue loc-tite and try not to over tighten the screws.

    That 5.5x5.5 I think is just to much pitch, you are so close to being a 6" prop plus you stepped up the pitch quite a bit. To much pitch and you find the motor will stall out at the high rpm and you really don't gain any performance.

    Right now I have mainly all 40C rated batteries but I think I have abused them a bit to much this year ;), I did have to retire a few. I just received 6 more yesterday and these are all 60C. This is including my 3S batteries too.
     
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