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Old Oct 03, 2012, 04:44 PM
Diverted by planks
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South Florida
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Originally Posted by St. Martin View Post
BTW, anybody ever land in that lake?

heh heh


On purpose? Not that I know of -- not authorized.

Accidentally? Well, let's just say some tennis shoes have been known to get wet from time to time.

It seems such a shame to not be able to use it, since some of us have sea planes, but it's just too close to picnickers etc, so definite no go.
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Old Oct 03, 2012, 04:47 PM
Big gov never Works
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Skunk Water, Rhode Island
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I lived in PB county for 20yrs. Lot's of canals! Just keep an eye out for the Moccassins!
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Old Oct 03, 2012, 07:16 PM
Extreme CNC Alloy EDF
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Originally Posted by 91-ZULU View Post
I thought the whole primary purpose of using a lower IR Hi C battery is so that one could fly at 90% + throttle setting MOST of your flight without puffing your battery. At least that is why I go that route. It is a total waste flying in sea saw mode an entire flight. There is no fun in that. If I am flying a jet I should be able to fly full throttle for most of the flight with out smoking something. Is it just me ?
+1, I set my jets up so I can fly them at WOT for most of the flight if I want to, a jet is a jet, if I want to do aerobatics I will get out an aerobatic model. Fast passes in an overloaded airframe then tooling back upwind to do it again 3 more times then the battery is flat, not my idea of flying. I flew the F16 years ago with 4 different setups in it, 90mph, 110, 125, & 138. The most enjoyable setup was the 3W15 at 110mph and only 38A on 4s, WOT the whole time and fast enough to be fun but slow enough to actually enjoy doing yank and bank circuits, vertical climbouts etc. It was light and nimble too.

Batteries, end of the day it doesnt matter if I am using a 35c or 45c pack, all batteries will get hot depending on the constant C you are running them at. I try to set my jets up for a max of 20c constant, 15c is the ideal target. Its the quality of the cell that counts for me, not the C on the label, I use my own brand of course and they are assembled from some of the best cells available, grade 1 cells that can handle abuse and have long cycle lives. I use 2+ yr old 25c 4000 packs in the CS10 vampire and 35c 3200 packs in the CS10 F16. The F16 is a very slippery airframe and its doing a good 100mph at half throttle, so I can fly around at 1/2-2/3rds constant and it flies like a jet. I also run an 80% FSA thrust tube in the F16 without issue. The vampire is draggy, I fly it at WOT much more, its a nice model to do huge imelman turns and grass scraping flybys, fast enough to be enjoyable but still scale looking.
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Old Oct 03, 2012, 10:30 PM
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"I thought the whole primary purpose of using a lower IR Hi C battery is so that one could fly at 90% + throttle setting MOST of your flight without puffing your battery."

That is not actually entirely correct either.....
There is FAR MORE to it all than all the simplistic generalisations that abound.

For eg, if we went by your statement above...
I am using a CHEAP 20C battery in my Vampire. A 5S 3000mAH 20C that runs at 43A to 45A, (800-850W from memory) does 130kph (easily over scale speed) and I fly it pretty well at WOT all flight, because the Vampire is draggy and needs that level of power to keep it at that good looking 'scale' speed. 3000x20=60A capable (supposedly). IR will be higher than a Nano....
The battery comes down 'warm to very warm' hardly puffed. A temp I consider 'acceptable' for the battery.
So no low IR there..... but a totally fine system, to fly at WOT all flight if you want to. (Thus debunking that 'purpose of low IR' comment)

The IR does not set the heat. The IR only alters the combo's (load R and battery R) balance, and thus the current it will draw. Throw in a lower IR battery and you will get more current, and thus more power/thrust from that motor/fan - but also remember that the motor/ESC must also be able to cope with that higher amount if you want it to work/last). The higher current, even over the lower IR, means more battery heat anyway.

In that exact same plane and combo, the only difference the Nano (lower IR) will make is that it will run the combo at more power, due to that balance of load and battery impedances and then if you ran that at WOT you will end up in the same boat.....
All you have done is run a combo at a higher power level, and the battery can do that fine - no better than the lower C battery did at its lower equilibrium power level. The lower C (higher IR) battery "auto limited" its current supply because of the impedance balances anyway..... the only real difference of the two batteries is what power they WILL, not CAN, drive the system at.
And it just so happens that in this particular motor/load case given, the actual motor impedance lends itself well to create those two balances, that are both good end results.

If you had a more powerful motor, that for whatever design reason presents lower impedance to the system (battery), then the scale of currents will go up. It will still apply to any battery used.... whatever their IR is, will now drop more volts over it than the motor because this new motor has lower impedance (resistance). Your "Low IR" Nano will now run hot if used at WOT all the time, and so will the 20C (which will still only drive the system at a lower current level than the Nano anyway).
If you do go to the more 'powerful' motor (and impedance is NOT just about motor power) you will need to increase the C of either battery, Nano and cheap 20C.

You can ONLY find out the answer to this current need by TESTING.... because the motor impedance (somewhat dynamic and governed by its load/fan), and battery IR, can't be truly known in advance.
So you plug in a battery (hopefully that you guesstimated to be somewhat appropriate!) and check the Amps, and the battery temp as it runs, and then you will know if THAT battery is suited to the task.
ie You plugged in a 2650mAh 30C battery and the resultant current was 45Amps = all likely to be fine. If it was 75Amps then surely won;t be fine! LOL

If you grabbed a 2650 65c Nano then, because of its lower IR the combo will drive to a higher power level - guaranteed. Because the battery IR (impedance) is lower and thus the motor gets more volts over it. You again check current... Say Amps are 53Amps now... easily within the Nano's ability. But if (comparing to the 2nd numbers of the 30C test) it goes to 85Amps (was 75Amps at 30C), then you are still fine and within the Nano's specs.

The real question is WHICH DID YOU NEED?
If the plane flew great on the 5S 3000mAH 20C already, all the Nano will achieve is give more power, higher speed that you never needed (or wanted?), at over 3x the cost of battery.
If the plane was lack lustre on the 20C THEN you are in the realms of justifying the Nano - because you DO need more power/speed.

Correct and optimal battery choice is not about Low IR at all. It is about adequate power, achieved within the batteries specs..... and if you have monetary sense, then also including the most economical way to have that end result.
From what I have found a high C (Nano etc) is not very often the best answer to that equation!!
3X the price, to achieve little better.... in power or lifespan etc..... I would want to be seeing triple the lifespan from it!!

Just for a reference, I have tested a Nano in my Vampire and the power increase is 12%.
So you pay triple the price, for 12% more power, and power use does not translate into SPEED at all.... not even half. eg speed gain will be 5%, due to the squared law of drag.
So you paid triple the price for...??? 10kph?? And maybe a bit longer lifespan.
It is still MILES short of economics.
But if you WANT, or need the speed.... then it is the only way to get it - almost.....

Also take note......
The Nano in the Vampire, giving you that higher power (say 53Amps versus the 20C using 43Amps) means LESS flight time of course..... but I guess you got that 10kph more speed, LOL.
You also drove the motor harder... hotter.... thus its lifespan reduces - that might be fine, if it was still within specs anyway, so the motor factor result is not as simple as one sentence either. But it is a factor that rises in importance as a higher power battery is used.
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Old Oct 03, 2012, 11:07 PM
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Quote:
Originally Posted by Slaanesh View Post
I'm running a L2855-2100 on 5S in a HET ME-163 Komet. Sounds great, though it's not super-duper fast. Can hand launch no worries.

I'm also running a L2855-2300 on 5S in a Hobbyking/ProEDF composite F-16.
It's really disappointing! It weighs 1350g ready to fly but it certainly doesn't produce anywhere near that thrust - I would say more like 1100g or so as doing a vertical test (holding it vertical and letting go) results in it dropping. It flies nicely but is "not-fast"

From memory, I'm getting about 620 - 650W on these.

I haven't checked the battery voltage so maybe that's the issue. I'm using 2200mah 5S nanotech 45C in each.
Or it could be the ducting, especially on the F-16 - the EDF us located right in the middle - probably a good 12 inches from the in-take.
Thanks for the replies fellas.

What exhaust diameters are ya'll running? You might want to check this on your birds Slaanesh. I'm running the CS-70 10blade fan in my Phase 3 EF-16 on 5s with the Turnigy L2855-2100, a 61mm exhaust diameter and I'm getting 47amps, 810watts and 35oz static thrust.
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Old Oct 03, 2012, 11:39 PM
Always Fly 2 Mistakes High!
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Houston, Texas
Joined Mar 2010
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Trying to setup ChangeSun Fan with new ESC

I just bought new Cyclone Power 85 amp ESC with 5 amp switching BEC. I hooked up to my eflight delta v15 motor and 10 blade motor.

After hooking it up it just kinda turns forward and then back but not smoothly. It jumps back and forth. I switched wires...no effect. I went through the programming modes setting timing to auto (default), low timing, high timing and still no effect. These motors (I tried 2 of them) work great with other ESC's. I then put back to factory restore mode and same thing.

Any ideas?

Thanks in advance.

Russ
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Old Oct 03, 2012, 11:49 PM
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Are you using the CS Fan. If yes why are you using the V15 instead of the BL32 ? Just curious.
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Old Oct 03, 2012, 11:56 PM
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Australia, VIC, Melbourne
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Do you have another ESC to try? It sounds like it is being 'driven' to that pattern.... by flakey signals for some reason. A faulty ESC(?). Or slim chance of one of the motor leads flakey (solder joint?).
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Old Oct 04, 2012, 12:05 AM
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Canton, Michigan USA
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Quote:
Originally Posted by PeterVRC View Post
Do you have another ESC to try? It sounds like it is being 'driven' to that pattern.... by flakey signals for some reason. A faulty ESC(?). Or slim chance of one of the motor leads flakey (solder joint?).
PeterVRC is right to check the solder joints. Cold solder joints occur far too often with low cost electronics we get from China.

Also check to make sure bullet connectors are tightly fitted together. Size can very between the male and female. A lose fitting connector will cause problems with the motor and esc synching up.
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Old Oct 04, 2012, 12:10 AM
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Australia, VIC, Melbourne
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Yeah, even the solder joints on the ESC itself. Probably even more likely than your own joints.
Basically one phase to the motor (of the three) is likely to be not getting there 'intact'.
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Old Oct 04, 2012, 08:33 AM
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Quote:
Originally Posted by dpowellmeii View Post
Thanks for the replies fellas.

What exhaust diameters are ya'll running? You might want to check this on your birds Slaanesh. I'm running the CS-70 10blade fan in my Phase 3 EF-16 on 5s with the Turnigy L2855-2100, a 61mm exhaust diameter and I'm getting 47amps, 810watts and 35oz static thrust.
Something is out of whack, in the CS10 test results, the L2855 2100kv on 5S got 63 ounces (1.8kg) of thrust on a test stand. Way too big of a discrepancy. In my own testing on 6S, I am only able to get 1.6kg or so, and this is on medium timing (turnigy trust 70amp esc). My guess right now is that for some reason, the motor/fan rpm is too low.
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Old Oct 04, 2012, 08:43 AM
Always Fly 2 Mistakes High!
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Houston, Texas
Joined Mar 2010
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Esc

All of the solder joints are my own with 5mm connectors. It's gotta be a programming issue or just a bad ESC. I was hoping for someone with CP ESC that knew some issue with it that would be easily fixed. Rats! I hate to send back to PW-RC to Phillip and wait weeks in the process.

Thanks for the feedback.

Russ

P.S. A Power 32 would be preferable if I had one...just trying this setup out to see how it works.
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Old Oct 04, 2012, 08:45 AM
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Originally Posted by tracknoob View Post
I don't see PVRC's posts anymore, but based on replies I can imagine what you guys are up against, with him promoting use of low C batteries in EDFs.

Fact is, today I flew with some new 60-120C batteries in a plane that used to get 30C batteries, and man, I love it. Size and weight is about the same due to technology improvements, but the POWER, the FLIGHT TIME and the BATT TEMP all were synergystically improved. More initial power let me throttle back earlier, lower internal resistance also let the throttle stay lower, and also kept the temps down.

All in all, I'd say if you are going.to 'spec' in a battery as a replacement, don't EVER be a cheap charlie and get low C batteries, instead UPGRADE and enjoy the longer times, cooler temps, more on-tap power, and longer overall life (more charge cycles and less chance to puff or damage).

Knowing PVRC is out there somewhere fuming at you using those premium cells is just sweet icing on an already delicious cake.

Life's far too short to try to 'just get by'.
It all depends on the application doesn't it.

For example I have an EDF that draws 74amps at full power. I decided to go with a 4000mah 25C battery. 30 flights later, the battery still performs flawlessly. Comes down warm, never puffs and gives good flight times. A 65C pack would have been twice the price, and at over 250amps max discharge would have been overkill for my application.
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Old Oct 04, 2012, 11:15 AM
Diverted by planks
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Quote:
Originally Posted by nighthawk0077 View Post
It all depends on the application doesn't it.

For example I have an EDF that draws 74amps at full power. I decided to go with a 4000mah 25C battery. 30 flights later, the battery still performs flawlessly. Comes down warm, never puffs and gives good flight times. A 65C pack would have been twice the price, and at over 250amps max discharge would have been overkill for my application.
Sounds like you are not 'just getting by' -- sounds like a good setup for you.

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Old Oct 04, 2012, 12:25 PM
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Quote:
Originally Posted by nighthawk0077 View Post
Something is out of whack, in the CS10 test results, the L2855 2100kv on 5S got 63 ounces (1.8kg) of thrust on a test stand. Way too big of a discrepancy. In my own testing on 6S, I am only able to get 1.6kg or so, and this is on medium timing (turnigy trust 70amp esc). My guess right now is that for some reason, the motor/fan rpm is too low.
The test results in the spreadsheet were done on a test bench with the intake ring on and no obstructions in the ducting. My numbers were taken with the fan installed in my Phase 3 EF-16 with an ESC installed in the ducting and a 61mm exhaust diameter.

Anlucas re-tested this setup on the bench without the intake ring and this is what he came up with. Post #3754

Quote:
Originally Posted by anlucas View Post
Much more reduction than I expected(about 50% reduction)......here goes.....L2855-2100kv + CS10 without a lip

4S 4000mah 25c
15.8V
28Amps
485Watts
0.55Kg thrust

5S 3300 25c
19V
37Amps
700Watts
0.75Kg Thrust

6S 4500mah 25C
22.5V
50Amps
1100Watts
1.1Kg trust....


****CAVEAT - To anyone else reading this. These tests were without an inlet lip and cannot be used to indicate possible performance of the motor/fan combo.


Two things impressed me.
1. How much lower thrust one gets without proper inflow to the fan.
2. The white noise generated was awesome....

With the lip on, the fan is very quiet when balanced properly.
With the lip off, inlet turbulence noise is just a great white noise generator.


It may be worthwhile experimenting with inflow disruption to generate white noise....
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