Originally Posted by Extreme_RC

The CS rotor is a high load, doesnt matter what the motor is "rated" for, fact is this rotor needs a V8 with torque behind it, not a 1.4L TSI engine from volkswagen Think long can inrunners with a decent amount of mass.

Or think 36mm outrunners with 5mm shafts in the 2k kv range, mounted behind the fan.

Originally Posted by Knife Liddle

Or think 36mm outrunners with 5mm shafts in the 2k kv range, mounted behind the fan.

+1....
This would be a hot idea, the motor would have to be balanced but the torque excellent. The large diameter motor in the airstream would run cool and the airflow would not suffer in a proper exhaust tube as physics works with us in that the airflow will just speed up arround the motor. Albeit there will be drag losses but it is definitely minimal compared to available power.

Eric B.

Originally Posted by James Frolik

I tested the CS70 fan with a HET 2W-20, 3s Zippy 2800, and Cyclone Power ESC-60A-SBEC controller on a vertical thrust stand. The stand's digital scale has zero-centering (to offset the stand's weight) and measures up to 3 kilograms in 1-gram increments.

I could only run the CS70 for about 15 seconds because the amps were too high — and the battery was not even fully charged. A full LiPo would be bad; this is not a good setup for the 2W-20 motor.

CS70
Note: This was not a freshly charged battery.
Load Voltage: 10.36 after 15 sec.
Watts: 774
Amps: 74
Thrust: 1148 grams

Watts and thrust on my test stand are nice, but the amperage is not.

Compare that to my 2W-20 test results (below) using a WeMoTec MiniFan with the same 3s Zippy 2800 LiPo, but now it's freshly charged. Here the input is over 1 volt more than with the CS70 (and a used battery). Thrust is only 20% less but the amps drop by nearly 50%. Interestingly, the watts drop by 46% without sacrificing too much thrust loss.

WeMoTec MiniFan
Note: Freshly charged battery.
Load Voltage: 11.78 after 30 sec.
Watts: 418
Amps: 37.9
Thrust: 917 grams

James, thanks very much for the measurements.

Although I don't have measured numbers, it appears that there are some differences between your measured amp-draw and what flylow2011 and myself observed (see post 3658). I have been flying CS-10 with 2W20 and 3S 3000mah, Thunderbird 55 for over 2 months now. Even with a good percentage of WOT, the battery was only warm after the flights.

Could you do 1 more test with the same 2w20 on WeMoTec Minifan with 4S, to see if the current is around 50A?
Thanks in advance with your help.

Originally Posted by AirX

+1....
This would be a hot idea, the motor would have to be balanced but the torque excellent. The large diameter motor in the airstream would run cool and the airflow would not suffer in a proper exhaust tube as physics works with us in that the airflow will just speed up arround the motor. Albeit there will be drag losses but it is definitely minimal compared to available power.

Eric B.

Hey Eric, I posted these pics earlier, but it`s a long thread and easy for stuff to get lost or missed.

This is a stock Turnigy 3126-1600 with a long shaft added and an extra bearing at the front. I`m using an aluminum collet style adapter for the 5mm shaft and it runs super smooth all of the way up.

I`ve used two diff CS-10 rotors on it and didn`t have to ballance or clock either one. I checked them for static balance and they looked good, so I just bolted them on and ran them. I`ve had the rotor on and off dozens of times and it runs smooth every time I put it on.


I just tested it today.......on 8s

29v
80a
2.32kw
44k rpm
245 mph efflux
?????? thrust

They make a 2200kv but HK doesn`t carry it. That should be the magic number for 6s, or 1850kv for 7s. .

I posted this stuff about 12 pages back, but now I see my pics were the last ones posted so now I`ve posed them twice, oh well, sorry.

I finished up my ERC alloy CS10 with HET 2W30 and tested it..... (with ERC spinner too)

I used 90deg extruded alloy for the flanges and 'splayed' them open by about 5degrees to get them to align accurately across their mounting plane. This is because a plain 90deg flange, fitted to a cylinder, will not give you a straight line across the mounting surfaces... you need something like 95deg per flange in this 70mm housing sort of case.
I was going to polish them up to match the fan, and will do that some time eventually, but I was too eager to test it all !

Results were pretty good, but not as 'amazing' as I would have liked/hoped.

HET 2W30-2200KV 6S 4000mAH 30C
63A 1260W for 1.9Kg thrust (after stabilising)
That was pretty well no better than the L2855-2100kv gives. Fractionally better. Same Amps, same Watts, but 100g more thrust for the HET. So I guess that shows it was a little bit more efficient.

HET 2W30-2200KV with 2x (paralleled) 6S 4000mAH 30C = 60C approx
71.7A 1520W for 2.15Kg thrust (after stabilising) (peak was 2.25Kg)
Now that is at least getting something of 'benefit'.... being able to go over 2.0Kg.... but you are still paying for it in Amps (of course), to much the same levels as the cheapie motors are doing anyway.
I don't have a 2x 4000mAH test on a L2855-2100kv for some reason, or even a 5800mAH 30C test for it, so I will go and do those soon to get more cross references.
I am guessing it is actually going to head upwards to results somewhat like the HET. Probably just a bit more Amps again - though by that power level (1500W) you are really pushing the L2855-2100 well over its limits, so it might not quite do it. And even if it does, it is never going to last long term! They don't even really like 1250W long term.

So the biggest advantage of the HET (or Leopard, TurningXK, Tacon etc) is that they will do the job 'easier' - far more near their truly capable specs - and last longer.
But also, if you want 2.0Kg, or more, the L2855's are not going to cut it.... for long, if at all. So you really want to aim those for uses of 1.8Kg (needs 1200W) or less.

At $77 for a HET, and $13 for the "limited ability" L2855's, I think I would rather the TurnigyXK's (50mm series or even better the 60mm series) - IF they had them! Because they are doing HET jobs for $32 or so. Basically half price or a bit under. Once you go to Tacon or Leopard, you are getting pretty well to HET prices anyway..... and I suspect HET come from Leopard really anyway. It is not the same Leopard series, but could be made for them by Leopard and just different can ends and small changes they requested.

And for aircraft you are happy with 1.8Kg (1200W) use or lower.... nothing can match the L2855 $13 price!

And Knife's 36mm idea is still an extremely good one for higher power results, at very good low costs, too. But you will need to do a fair amount of engineering yourself, which I think the majority of people are not going to be able to do.
I could do it, but even I cringe at the idea of all the effort, hehe
How about "Knife's CS10 36mm Power Systems" for a business name.... LOL
...
..

Oh yeah.... Once again the testing shows how pathetic battery specs are....
"4000Mah 30C sustained" = 120Amps ability... yeah sure. Pairing two of them up gives 10A more, showing that the single battery was not capable of even 70A at all, let alone sustained. (Which the Volts sag also shows).

Of course it is well known to aim for 1.5x the Amps rating you really want... but not even that is being met. When just over 50% of the claimed Amps ability is being met, under notable battery duress (volt sag), the number you really need is more like TWO TIMES the Amps you want.
Which is also of course why many people do push out to 60C+ batteries for good power systems.

Basically.... take any listed C rating as HALF of what it can truly do.

So I am sure that ALL of my tables of results could push out more thrust.... but would also need more Amps for that too.
As long as the tests list what battery (or batteries) were used, and all the specs of items used, that is all a potential user needs to know for what THAT total setup WILL actually do.
Though still not an -in-plane result, which will depend on what plane it is.....

I would say that for all my tests, whatever I get for PEAK values (which I have but never list) is what a 65C battery would very likely sustain (with its own higher initial peak).
So for CS10's, as a general number to throw onto it..... add 200g thrust if you are going to use a 65C, and my test was with a single battery. That will be pretty close in the ballpark.

Originally Posted by eliu

Post #4518

James, thanks very much for the measurements.

Although I don't have measured numbers, it appears that there are some differences between your measured amp-draw and what flylow2011 and myself observed (see post 3658). I have been flying CS-10 with 2W20 and 3S 3000mah, Thunderbird 55 for over 2 months now. Even with a good percentage of WOT, the battery was only warm after the flights.

Could you do 1 more test with the same 2w20 on WeMoTec Minifan with 4S, to see if the current is around 50A?

Sorry, I have no 4s packs and I do not plan on buying any, either. I plan all my models based on a maximum 3s power supply.

My Zippy 3s 2800mAh LiPo is rated at 30C and I do not recall the battery temperature. But after only 15 seconds run time it likely wasn't anything noticeable.

The POWatt Meter is not highly accurate, hence it's inexpensive price. But it's a good ballpark figure. I will add that, although my CS70 fan sounded okay, I have not balanced it.

Originally Posted by James Frolik

Sorry, I have no 4s packs and I do not plan on buying any, either. I plan all my models based on a maximum 3s power supply.

My Zippy 3s 2800mAh LiPo is rated at 30C and I do not recall the battery temperature. But after only 15 seconds run time it likely wasn't anything noticeable.

The POWatt Meter is not highly accurate, hence it's inexpensive price. But it's a good ballpark figure. I will add that, although my CS70 fan sounded okay, I have not balanced it.

James, one possible reason for your higher amp draw is if you have high timing set.

Originally Posted by PeterVRC

Results were pretty good, but not as 'amazing' as I would have liked/hoped.

I suppose its good thing you didnt spend $160.00 on a TJ70 housing then!

Not sure what the TJ housing part meant there? It doesn't seem related to the quoted comment at all.

I would get the same result from the stock plastic housing of course. The only real use of using an alloy, or CF, housing is some more rigidity for coping with higher powers. Alloy for a bit of cooling aid - but it is not much really. And a bit of a sound difference - it actually sounds more 'metallic' and I expect it has less 'plastic flex reverberations' occuring of course.

The housing itself is only $45 and a beautiful bit of workmanship, worth that cost - the bigger question is do you need it? At 2.2Kg thrust, not needed really. But if you like technically sound things better, I guess it is the perfect answer for that. Seeing it is pretty much the same weight as doing it in plastic anyway - close enough not to matter.
Note you would have to buy a CS10 also, to get the rotor and shaft adaptor etc, so the total would be $60 for the fan/housing parts.

I will get at least one more, to modify into outrunner use (needs the motor mount area machined appropriately) and then do some bench and flight tests with that. Mainly for sound and vibration/reverberation reasons. If that proves to be of good use than that would add another reason to possibly use them, versus the extra cost.

Knife's "36mm Outrunner via extension" idea is another one that would do well with the alloy housing, as you are heading to quite high power by then. But the 3126 would need to run on 8S for that! It could probably do 2000W OK I would think. So about $90 total for 2000W to do that idea! (or just stop at 7S). There is probably some good and cheap 2200kv 36mm somewhere (?) that would be better for 6S use.

Originally Posted by PeterVRC

Not sure what the TJ housing part meant there? It doesn't seem related to the quoted comment at all.

I was comparing the prices of housings. Wasn't hard to figure it out from that comment?

I would get the same result from the stock plastic housing of course. The only real use of using an alloy, or CF, housing is some more rigidity for coping with higher powers. Alloy for a bit of cooling aid - but it is not much really. And a bit of a sound difference - it actually sounds more 'metallic' and I expect it has less 'plastic flex reverberations' occuring of course.

No you would not get the same results using a third party housing compared to the stock housing. Stator design has an influence on redirecting the flow and swirl coming off the blades, therefore the efficiency. Others on these forums will tell you the same.

If your running a 'hot' set up you'd want every bit of cooling. It adds to longevity. Unless your using an outrunner.

The housing itself is only $45 and a beautiful bit of workmanship, worth that cost - the bigger question is do you need it? At 2.2Kg thrust, not needed really.

That's contradictory.

A 70mm fan pushing 2.2 kg of thrust is a high powered fan IMO. The forces exerted on those blades are enormous. I don't think i'd trust a flimsy plastic housing to contain debris in the event of an FOD, even if it's installed in an airframe.

Knife's "36mm Outrunner via extension" idea is another one that would do well with the alloy housing, as you are heading to quite high power by then. But the 3126 would need to run on 8S for that! It could probably do 2000W OK I would think. So about $90 total for 2000W to do that idea! (or just stop at 7S). There is probably some good and cheap 2200kv 36mm somewhere (?) that would be better for 6S use.

Which 70mm airframe is going to take 8s? Most have room for 4s, 6s max.

Honestly, i've been watching this thread for a while and I get the feeling that you're setting your expectations too high.

Lets just clarify: 2kW and 2.2+kg of thrust for 70mm fans is on the high end of the spectrum. Most airframes aren't going to have that sort of power available to them. Most are running a typical 4s set-up with 1.5kg of thrust. Quality motors aren't going to give you significant boosts in performance. They're just going to run closer to their stated specifications.

Has anyone compiled a list of vendors to purchase this fan from? Thinking of buying one to do a 800w 4S application for my F-18.
Also any vendors sell these balanced with a motor attached based on requested specs? Obviously that service wouldn't be hobby king priced, but I think that would be ok for someone not skilled at balancing fans and wants a heart transplant for their plane, like myself

Thanks for posting your results Peter, that is very informative. Couple of questions, is the Turnigy L2855-2100 a drop it into the CS-70 or do I need some adaptors?
And can you post a link to the TurningXK you mention please?
Thanks!
E

Originally Posted by earaoz

Thanks for posting your results Peter, that is very informative. Couple of questions, is the Turnigy L2855-2100 a drop it into the CS-70 or do I need some adaptors?

Drop fit. Nothing needed. Just make sure you have the 4x M3x6 screws.