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Old Nov 23, 2010, 12:13 PM
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Originally Posted by TANGOSIERRAROM View Post
Maxthrottle if the kV of the moter stays the same and you add 3.7 volts the fan will spin faster and the amperage will go up, not down. You will need a bigger ESC if you are marginal at the moment.

If you reduce the motor kV, to get to the same rpm as the original set up achieved, but with the additional voltage then the amperage will go down but then the performance will not alter very much. Although there maybe a slight reduction in wing loading but I think that would be marginal as a bit of extra endurance is alluring so most of us do not reduce the battery capacity any more than is required to get back to the original pack's weight.

Could be of course that I have missed your point?
You are holding a constant where I was not. I said increasing the volts, if you can find a motor that can handle it. Meaning that I wasn't talking about keeping the same motor with the same KV.

Not sure what you are arguing or correcting especially when your comments from the second paragraph on supports what I said.
He also wasn't looking to get the same performance but to increase which is usually better served by increasing from 3S to 4S.
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Old Nov 23, 2010, 06:03 PM
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Originally Posted by snivilous View Post
I agree, easy flying airframes can get boring My F-4 was from a couple years back, so recent brushless systems are a lot better than that one had. It may fly fine, it's just my 64mm F-4 was horrible, but that may have been just me or a poorly designed airframe. Good luck with it though!
I plan on putting a Sapac motor in my F4. My 64mm F4 I'll just keep as is.
I'm happy with the way it flies & sounds

F-4 Phantom 70mm EDF (Repainted) (2 min 4 sec)

Jolly Roger F4 Phantom (64mm) (3 min 50 sec)
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Old Nov 24, 2010, 03:16 AM
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dubai
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Quote:
Originally Posted by Maxthrottle View Post
You are holding a constant where I was not. I said increasing the volts, if you can find a motor that can handle it. Meaning that I wasn't talking about keeping the same motor with the same KV.

Not sure what you are arguing or correcting especially when your comments from the second paragraph on supports what I said.
He also wasn't looking to get the same performance but to increase which is usually better served by increasing from 3S to 4S.
hay max as u know i'm still new beginner so i just try to understand.
from this equations
RPM = Kv * voltage
torque = Kt * current
Kt * Kv = 1 (IN THE MKS SYSTEM) or some crazy constant in other systems.
power = torque * RPM = volts * current (with some constants to fix units of measure)
i can see that if i change the kv for the engine and that for the engine can handle more voltage its mean oalso the current will be high also . or not???
or u mean when i will get the higher voltage i will not need in that case the high current ?!!
can u explain more bro ?
and what about if i used battery with 3000 mah wiyh 30c instead of the 2200mah with 25c . if that will effect the power and the speed or just to make the flight time longer ?
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Old Nov 24, 2010, 09:35 AM
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Have a quick look at the figures Don gets with his motors. Compare 3s in the GWS 55mm on this link with the 5400kV motor,http://donsrc.com/cart/index.php?act...d&productId=50
with the 3s and 4S in this link in the same fan with the 4800kV, http://donsrc.com/cart/index.php?act...d&productId=52

For performance go for the 4800 on 4s but you will use a few more amps but not many for about a 17% performance gain over the 5400kV motor.
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Old Nov 24, 2010, 11:40 AM
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dubai
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Quote:
Originally Posted by TANGOSIERRAROM View Post
Have a quick look at the figures Don gets with his motors. Compare 3s in the GWS 55mm on this link with the 5400kV motor,http://donsrc.com/cart/index.php?act...d&productId=50
with the 3s and 4S in this link in the same fan with the 4800kV, http://donsrc.com/cart/index.php?act...d&productId=52

For performance go for the 4800 on 4s but you will use a few more amps but not many for about a 17% performance gain over the 5400kV motor.
hay bro thanks alot it was really helpfull info i jst dont have enough place for the 4s even the 3s with 2600 mah is longer so can i use the 3s 2200 mah 25c or no ? and if so so haw many minets will be the flight if i'm doing now 6 min with the twin 2315kv and twin esc 20a ?
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Old Nov 24, 2010, 12:59 PM
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Originally Posted by will3kgt View Post
I plan on putting a Sapac motor in my F4. My 64mm F4 I'll just keep as is.
I'm happy with the way it flies & sounds
Your Phantoms fly awesome, very very smooth flying. I might be picking your brain later with the 70mm set-up if you don't mind.
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Old Nov 24, 2010, 01:05 PM
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Quote:
Originally Posted by TANGOSIERRAROM View Post
Have a quick look at the figures Don gets with his motors. Compare 3s in the GWS 55mm on this link with the 5400kV motor,http://donsrc.com/cart/index.php?act...d&productId=50
with the 3s and 4S in this link in the same fan with the 4800kV, http://donsrc.com/cart/index.php?act...d&productId=52

For performance go for the 4800 on 4s but you will use a few more amps but not many for about a 17% performance gain over the 5400kV motor.
Quote:
Originally Posted by bikaso View Post
hay bro thanks alot it was really helpfull info i jst dont have enough place for the 4s even the 3s with 2600 mah is longer so can i use the 3s 2200 mah 25c or no ? and if so so haw many minets will be the flight if i'm doing now 6 min with the twin 2315kv and twin esc 20a ?
Guys just catching up. Think T illustrated what we were both talking about. Bikaso you've highlighted the other side is fitting it into the model and like I started with can the wings support the setup to make it worth it.

There are a number of calculators for this sort of stuff (http://www.s4a.ch/eflight/fancalc_e.htm) that can make it easiers (See also; http://www.rcgroups.com/forums/showthread.php?t=606703).
Some calculators estimate flight time, thrust to weight etc but generally if your drive setup is efficient.

This thread is about and EDF check list not specifically the F-14 so we can take it over to the main 55mm F-14 thread or the thread Bikaso started.
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Old Nov 24, 2010, 06:29 PM
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HK edf motors chart.
With data in HK site.


Manuel V.
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Old Nov 25, 2010, 08:31 PM
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4s with 14.5Volts projection

4s can be used with the other marked with yellow
The cream is well marked and will be very reliable to 4s.
Those marked with pink pre-tests can be used with caution.
Those marked in red should not be used,

Manuel V.
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Old Nov 26, 2010, 12:00 AM
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Thanks Manuel V
Did you put those together yourself or you got them from HK?

Either way Bikaso if you look at the 4S chart compared to the 3S chart, the 4S has more watts/gram but the amp draw is generally close to the 3S. Its just harder to find small 55mm 4S motors.
The bigger models use this lower amp draw to reduce the weight, cost and need for very High Amp ESCs, while keeping the system cooler.
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Old Nov 26, 2010, 01:19 AM
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Max

H King put in your home page:a KV, thrust ,ampers to 11.1 v., RPM with load, and not load,

In the prediction to 4s is 1.61 * ampers 3s.
consideri 11.1 to 14.5 Volts.

Im using 2610 motors for GWS55 with 3s and 4s. around over 40,000 rpm.

But i like to rewind all my motors., even EDF motors.
http://www.rcgroups.com/forums/showthread.php?t=1185976

Manuel V.
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Old Nov 26, 2010, 02:07 AM
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Ah not sure what you are comparing but using your 2610-4500 motor for the increase of 17amp (27-44) going to 4S you more than doubled the watts. The Watt/gram went from 5.99 to 12.59. Not sure if you guys are understanding when I say less amps. Relative to the final watts, rpm and the watt/gram increasing the voltage comes out better since its lighter, cooler and doesn't need a heavier expensive high amps ESC.

I'm running an ARC 2858-1 in the 1.7W range on 6S but with under 80amps pushing a 70mm wemo to 2.5Kg of thrust. You can't get a lower Volt motor with just higher KV to get near that efficiency, power, rpm and lower amps. The amps are so high it starts melting solder and the windings etc.

What kind of thrust do you get from the 3S vs the 4S off the GWS55? You mention both 3S and 4S over 40K but you don't say which one is achieving this. And what are the amp for either on that fan under load?

Either way I think I'll be looking over the Starmax F-14 70mm instead. I can add rotating retracts to it.
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Old Nov 26, 2010, 02:53 AM
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What kind of thrust do you get from the 3S vs the 4S off the GWS55? You mention both 3S and 4S over 40K but you don't say which one is achieving this. And what are the amp for either on that fan under load?

Ok i have a GWS55 with 3s and 4s. but:

Motor 2610
29,000 rpm, 7.89V, .84A, Kv=3675.

3s: 35,600 rpm, 11.06V, 16.58A 183 Watts. Kv Ratio 87.5%
4s:41,800 rpm, 14.02V, 23.86A 334.5Watts. Kv Ratio 81.12%

for over 40,000 rpm i needed highy kv with 3s.
REGULARITY I REWIND WITH LESS TURN FOR THE TARGET.

Of course an engine works best at a high voltage. and in these cases of EDF's always better to increase volts and decrease amperes.

The problem is that a motor can not increase the voltage while sustaining the load because the engine ended up burning.
so that row is in pink and others in red. reds are useless. 4s these engines can be used only up to 10 watts per gram.

Manuel V.
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Old Nov 26, 2010, 12:56 PM
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And as you know the Voltage levels of a motor is dictated by the winding and construction so as I originally recommended to Bikaso, get the best of all options by finding a motor that can handle the higher volts and over all you should come out with a lighter setup drawing less amps, run cooler but outputing higher power. Which is what he asked for.

There are several others in the list that you presented in 4S that are doing well over 183watts with much less increase to the amps than would be found if you just increased the KV.

I'm gonna stop writing as I keep forgetting this is way off topic for this thread.
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Old Nov 29, 2010, 12:00 AM
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I just took my first foamy edf for a test spin today. The weather sucks; horizontal snow fall gusting to 45mph.

Something to add to the list, consider your flying fields. In my case I have pasture land in the summer and in the winter I take a tractor and blade off a dirt road. Had I realized that the F-15 was prone to kicking up rocks into the intakes, I would have gone with something different. Also, I plane on doing some hand launching and belly landing so something like a F-16 would not suit me well.

It was a good excuse to do some balancing of the chipped up fan and reinforce the fuse after a hard landing.
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