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Jun 14, 2012, 10:08 AM
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Tamjets's Avatar
Originally Posted by tracknoob View Post
self-censored, after looking up the history of the source.

Folks, do please check the post history of folks before you bother with answering any contentious posts -- you might just find they LIKE to mud wrestle.

I will take my energies in other directions.

Cheers, and remember everyone HAVE FUN! We are playing with toys, after all!

Cool, expensive, somewhat dangerous and complex toys, but at the end of the day.... toys.

I had to edited my post just clear the miss commucation on other party had no clue what happen. But the party is wrong is ok for him breaking rules.
I take the high road and like you put my energies to the fun.
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Jun 14, 2012, 03:51 PM
You are a "go" for reentry
Maxthrottle's Avatar
Originally Posted by Flip Flop View Post
Hey Max its just about 1:1, it will hold itself up for a second or two before falling slowly.
I'm gonna have to look back at your setup but its nice to see you got past the supposed complications others thought they had with the CS that duct and motor.

Does it accelerate any slower with that weight?
Jun 14, 2012, 05:56 PM
Registered User

62A 22.1V 1377W for 1.9Kg Thrust

56A 21.2V 1188W for 1.68Kg Thrust

It is pretty well dead equal to the L2855-2100
It just weighs more.... costs more.... MIGHT be a better motor construction-wise overall, and thus last longer. But I guess it shows that both do their KV rated jobs fine and I would think that shows that is about what any 2100kv motor numbers will be approximately. Plus or minus a bit for ESC, leads etc variations.
But basically looking at about 1.7Kg thrust ongoing (the 1.9Kg peaks).

Meanwhile, the L2855-2300 had done 1.9Kg Thrust ongoing at 67A, which is in-line with thes results too, so it can do those numbers (and any 2300kv likely to also) within its stride.
So if you want 6S 62A area draw.... go 2100kv, or for 6S 67A draw (more thrust of course too) go for 2300kv.

Keeping the XK2850 within it listed specs needs 5S, and that gives:
44A 17.6V 777W 1.32Kg Thrust ongoing. (peaks were about 1.5Kg area)
But with the heatsionk on it 6S seemed it would be fine - but of course must reduce bearing lifespan.
Jun 14, 2012, 06:28 PM
The best in EDF since 2005
Extreme_RC's Avatar
Originally Posted by PeterVRC View Post
56A 21.2V 1188W for 1.68Kg Thrust
Meanwhile, the L2855-2300 had done 1.9Kg Thrust ongoing at 67A, which is in-line with thes results too, so it can do those numbers (and any 2300kv likely to also) within its stride.
So if you want 6S 62A area draw.... go 2100kv, or for 6S 67A draw (more thrust of course too) go for 2300kv.
You got any rpm figures Pete? Would be helpful to judge all the numbers.
The 2W30 pulls around 65A for 2.1kg thrust which gives you a good benchmark to work off.
Jun 14, 2012, 07:07 PM
Registered User
I have to check the vid's but it was around 36k rpm... though I still don't know what I can trust in the KV meter and that is why I didn't include RPM readings.

I used 4 pole (meter set to "2") and if that was wrong, it would mean any other setting would give a hugely different number - that would be quite a way outside of any correct range.

What RPM was that 2W30 giving those numbers at??
And I would assume that is a peak number of 2.1Kg. The XK2850 (and L2855 too really) peaks are shorts and of course vary according to battery, so it wouldn't be hard to get "2.1Kg" with a better battery.
And I guess the ongoing output would be better in that better battery case too.

So a problem in results is also what battery/ESC was used.... and I would expect if I ran a HET test it would still be close to these other motors.

Part also is that I am using 'so-so' Turnigy batteries. But also as my numbers are leaned towards the weaker side, eg not "peakest of peak" split second etc because that is a useless number for real-world application, and anyone will get at least those same numbers as mine at worst - and for 'ongoing' - but even a bit better with a better battery or better ESC.
So it is sort of an "Anyone will get at least these numbers guaranteed" from the CS10 and this motor (on a bench).
And the main use of that is they can know the minimum starting point they will have, and then just guesstimate what the in-plane will hopefully give due to losses there.
But also good for direct comparisons of the various motors and cells I have tested them on.
Jun 14, 2012, 07:19 PM
The best in EDF since 2005
Extreme_RC's Avatar
My figures are from a 60 second test using a 1.5yr old ELITE 5000mah 35c pack. RPM is over 39K and stable. I dont ever post peak numbers. Always use the same ESC for testing, an HW80 that has been in use for 2+ years now, so its well run in LOL

36K rpm is around 1.7kg thrust, so we can roughly calculate your loaded Kv to 1700. Mine is 1835 on the old 2W30 with 3.17 shaft, the new ones with 4mm shaft gave different numbers when I last built one but I didnt have my good E-meter connected, only a cheap meter/controller, need to recheck one of these.
Jun 14, 2012, 08:13 PM
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Flip Flop's Avatar
Originally Posted by Maxthrottle View Post
I'm gonna have to look back at your setup but its nice to see you got past the supposed complications others thought they had with the CS that duct and motor.

Does it accelerate any slower with that weight?
The acceleration, top speed and vertical is good, it did not seem to notice the extra weight that much.
This is the third setup I've tried on this jet and is by far my favorite as far as power and efficiency goes.
Jun 14, 2012, 08:18 PM
Registered User
Originally Posted by houstonderk View Post
Well here is my presetup. Probably not going to be done before leaving for 6 months but nice to look at nonetheless. I had this setup with the stock 50 amp and motors and was just a beast, so now fully pursuing this plane setup with more power.
Sweet, what A-10 is this?
Jun 14, 2012, 09:12 PM
Registered User
Well, that HET is 100kv (140kv) higher motor... so those higher numbers are what it should do.
And the L2855-2300 does the linear enough step upwards of those other three motors too (Xk2850-2100, L2855-2100, HET 2W30-2200). Plus allowing "KV spec tolerance".
So that would suggest they are all coping with their loads totally fine, and attaining the RPM they 'should' (loaded kv).

The HET Amps being just a little bit lower. 3A or 4A area it seems. Overalll a bit better.... but 5x the cost of the L2855. And would hopefully last a LOT longer.

For the XK2850, At $32 I guess it should be a better motor than the L2855... though results-wise it is identical really. You would hope it would be doing that job 'easier' than the L2855 and thus last longer. But only time would tell that.
It is half the price of a HET, and it probably is worth about that 'half step' that it costs from L2855 to HET.
I would only rate it, recommend it, above the L2855's IF it proves over time that it lasts at least 3x longer (bearings? or whatever). Because that is what it would need to do to recover its extra cost.

At $12 the L2855 is virtually a disposable item... pretty much like batteries... though a typical 6S used is more like $70 area. So $12 is easily even further into 'disposable' area.

I should have logged my Meteor's L2855-2300/CS10 5S flights... it is still going, but occasionally has an 'odd' noise at lower RPM. It would have to be over 30 flights at least. And pretty well 90% WOT minimum all flight. So.... hmmmm.... for $14 (inc freight) I would hope to get 100 flights from the motor, to call it 'value', and then any more is a bonus. LOL
I am going to up it to 6S to see how it flies with that (I have to upgrade its ESC for that), and also try to gauge what the motor thinks about that !! (heat tests/checks). Or run that one until it fries....
And the CS10 should sound even better than it does now, with the extra RPM.
Jun 14, 2012, 09:16 PM
Registered User
I "want" to buy a HET.... just for testing/use curiosity. And to see if I can conclude it is worth its extra cost, or not. But so far, even from other results and 'educated guess' thoughts about it, it just doesn't add up that it could total up to be worth it.
If the L2855 did not exist..... THEN there would be a far narrower margin to all other motors available. But this $12 'value wonder' is messing up the motor world. lol
Jun 14, 2012, 10:40 PM
The best in EDF since 2005
Extreme_RC's Avatar
Quick test of a current motor gives me 1899 under load. You would need to check the HK motor to see if it is actually 2100 or not.
Jun 14, 2012, 11:00 PM
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gchrisgo34's Avatar
what is thermal paste used for, with these edf units?
Jun 14, 2012, 11:45 PM
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Michael Paxton's Avatar
Originally Posted by gchrisgo34 View Post
what is thermal paste used for, with these edf units?
It's put between the alloy center housing of the shroud and the motor to transfer the heat.
Jun 15, 2012, 12:29 AM
Registered User
Or also between the heatsink and motor, if that is all you have (eg for a plastic fan housing).
You can use computer thermal paste, there are some useful 'thickish' grey types. eg Arctic Silver etc.
Not the thinnish white cheap stuff.
Jun 15, 2012, 12:36 AM
Registered User
With the load RPM, that will also drop more if the motor is not truly capable of driving the load. Magnets not large enough, strong enough. Windings etc.
eg Looks like the HET can do that better than the other three, which all fall into similar loaded RPM sequence.
But those other three are also specced lower than the HET, so you would expect they are made that bit 'weaker' too.
Still not bad to get 10% less specs, for 80% less cost! hehe (and probably 1/5th the life, LOL)

As for lifespans... that would be interesting because I would think the main item in the motor of 'lifespan note' would be only the bearings. As long as you aren't frying the windings or magnets (glue) then they would probably go on doing their jobs fine for a very long time anyway.
And I don't think any of the bearings used (cheap or HET) are made for the high RPM being used really... though 'better' bearing brands will last longer at the level of duress.
So again, it just comes down to cheap motors being a disposable item.... not even worth spending $6 or $8 on better bearings really. Spend $12 on a whole new motor eventually....

As for bearings..... they themselves are probably the MOST important reason for balancing fans well !!!
A somewhat unbalanced fan will most likely survive physically... housing, rotor... but a bearing being pumelled at 30k to 40k RPM, with varying rotational loads due to the fans imbalance at those high centrifical forces, will wear at a much much faster rate! (than a balanced fan's motor bearings).

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