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Old Aug 16, 2014, 01:05 PM
Vertical approach specialist
potshot's Avatar
Northeastern Illinois
Joined Mar 2009
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Quote:
Originally Posted by goldguy View Post
deadhead:

Check out the HK US warehouse for SK3 motors or here....... http://www.strongrcmotors.com/Motors.htm for the KEDA brand.

You'll have way less problems with motors that use the back plate 'X' mount.

Frank
Does that Keda 2370 have the same whistle as the BWs? I have four blue BWs that I could use on a quadcopter, but don't want to quadruple the whistle.
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Old Aug 17, 2014, 07:32 AM
flyin' fool
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Vancouver Island, Canada
Joined Jul 2003
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He KEDA 2730 is still blue and of better quality than the HXT/Turnigy version. I've still have one and it doesn't whistle, although it's been rewound.
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Old Aug 19, 2014, 02:01 AM
Registered User
Los Angeles, CA
Joined Mar 2004
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I have a 28 inch on the bench made with FFF foam.

What sizes motor and ESC will I need?
Where is the good CG spot?

Thanks
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Old Aug 19, 2014, 05:17 AM
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Marlborough, Massachussetts, United States
Joined May 2002
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CG at 25% = 7"

Motor/esc/battery depends on weight of airframe. You want at least 1:1 thrust to weight. Thrust is more important than speed, so go for a motor that will spin a big prop, at least 8".
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Old Aug 19, 2014, 09:57 AM
flyin' fool
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Vancouver Island, Canada
Joined Jul 2003
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Got my HK NutBall kits. Very nicely done and a cool little motor too. All I need are some small lipos and to get the bench cleared.
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Old Aug 19, 2014, 09:58 AM
flyin' fool
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Vancouver Island, Canada
Joined Jul 2003
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Quote:
Originally Posted by lv2soar View Post
I have a 28 inch on the bench made with FFF foam.
What sizes motor and ESC will I need?
Where is the good CG spot?
Thanks

What have you got in the way of motors, ESCs and lipos, or do you need to order something? Also, you'll need no less than a park size servo.
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Old Aug 19, 2014, 10:47 AM
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Los Angeles, CA
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Quote:
Originally Posted by goldguy View Post
What have you got in the way of motors, ESCs and lipos, or do you need to order something? Also, you'll need no less than a park size servo.
I haven't weight it yet
I have some HXT 9 grams, some 10 and 18 amp ESCs, but no motor.

Was thinking of the Turnigy or HXT 2730 - 1500kv. I used that motor on most of my 32"EPP plane. You think that will work on my 28" Nutball?
Thanks
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Old Aug 19, 2014, 11:09 AM
chuck
santa barbara, CA
Joined May 2009
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Quote:
Originally Posted by lv2soar View Post
I haven't weight it yet
I have some HXT 9 grams, some 10 and 18 amp ESCs, but no motor.

Was thinking of the Turnigy or HXT 2730 - 1500kv. I used that motor on most of my 32"EPP plane. You think that will work on my 28" Nutball?
Thanks
the hxt900 are perfect.

10 or18 will be fine depending on motor.

i use a 40 gram motor on my 28 " er ............ cg is much easier to get w/ the weight up front and i like the power using 1000 2 cells . some of this depends on the weight and current balance point of your bare airframe . the heavier the airframe (for it's size) the more weight behind the 25% cg you have that must be offset by motor weight ( and or battery)

the 2730 will work but power will be down , for sporty performance .

chuck.
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Old Yesterday, 12:32 AM
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Ashford. Kent. England
Joined Feb 2005
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+1 to that post 12605 reply.. the gear you use should suit the final weight of your model..
At 28" it can go either way... its more likely to be a border line model, if the model comes out light (10oz) then what you have is fine, if its a lump like I usually end up with ( at 14oz+) then a bigger motor and small metal geared servos will be better..

Aim at a high thrust to weight ratio for best performance.. a 1.5:1 thrust to weight will be great... 1:1 is ok ...a lot less than 1:1 will fly a nutball but it wont sparkle...
I have flown a 32" on that motor... it flew ok, but was only suited as a trainer, very slow and docile ..
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Old Yesterday, 02:42 AM
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Los Angeles, CA
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Quote:
Originally Posted by davereap View Post
+1 to that post 12605 reply.. the gear you use should suit the final weight of your model..
At 28" it can go either way... its more likely to be a border line model, if the model comes out light (10oz) then what you have is fine, if its a lump like I usually end up with ( at 14oz+) then a bigger motor and small metal geared servos will be better..

Aim at a high thrust to weight ratio for best performance.. a 1.5:1 thrust to weight will be great... 1:1 is ok ...a lot less than 1:1 will fly a nutball but it wont sparkle...
I have flown a 32" on that motor... it flew ok, but was only suited as a trainer, very slow and docile ..
Dave
Just to clarify, the weight is the airframe only, correct?
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Old Yesterday, 10:55 AM
flyin' fool
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Vancouver Island, Canada
Joined Jul 2003
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That would be total or flying weight. My 26 incher weighs in at 15.5 ounces (4 oz. per sq. foot) RTF and I ran out of servo power with HXT900s and switched to GWS 18 gram 'park' sized servos. That was doing extreme flying. If your just cruising around you may get by with nines.

Weight 'rules of thumb' or light is might......................

#1........ one ounce is equal to one volt. Add one ounce and lose one volt in performance, lose one ounce and add one volt in performance. Voltage is RPM and RPM is thrust.

#2........ one ounce at the back end is worth three at the front. That would be more or less depending on the CG.
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