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Old Jan 30, 2013, 06:15 PM
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Originally Posted by PAT-T View Post
i decided to run my pushrods under the wing for flaps and ailerons, no bending or whatever, and cover them with fairings.

Pat
That looks like the easy set up for sure. Think I'm gona try to make the internal routing work,, I have a couple ideas,, manager at hobby store where I bought the mystique said slightly bent the flap linkage and enlarged opening and cut a slight groove in trailing edge spar reinforced it with Ca said he gets about 60deg flap travel
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Old Jan 30, 2013, 07:43 PM
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Just tried my first motor prop combo out on wattmeter,, using E Flite BL 25 1000kv motor out of e flite yak part no. EFLM3700 bout same size and weight as reccomended power 25
870 KV motor except this is 1000kv,, using carbon cam aeronaut 13x6.5 blades with e flite spinner,, figured I'd have to prop down with that higher KV motor,, this motor designed for a front mount so no issues with wires and no prop shaft reversal ,, NICE!! My friend had one laying around so he gave it to me ,, but at $69.99 I don't know why e flite didn't reccomend this motor in first place. :-). So,,, the test : runs very very smooth TONS of POWER,, got 54-55 amps at 550watts,,, should pull this plane up pronto!!! Battery and speed controller after about 1 1/2 -2 min running static got a little warm but not much, motor got slightly hot,, but not unreasonably so,, plus in the air with air flowing over it will be cooler and when prop unloads in air maybe amp draw down to about 52-53amps,, well within limits of ESC that barely got warm,, so be interesting to see what she'll do in the air with this motor prop combo. So for those who don't want the hassle of reversing prop shaft and trying to not have motor wires rubbing with the reccomended motor,, this motor : e flite BL25,, EFLM 3700 is a drop in replacement,, you'll need to get 13x6.5 blades ( got mine at esprit models) and they fit fine in e flite spinner
Here's a link to somebody that sells that motor. http://www.redrockethobbies.com/E-fl...p/eflm7300.htm
Oh,, and if you don't want to use E Flite spinner,, the aeronaught 40mm turbo spinner with a 42mm yoke fits fine too,,, but the e flite spinner IS nice looking and about 1/2 oz lighter than aeronaught spinner
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Old Jan 30, 2013, 08:59 PM
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I found this substitute by value hobby (850kv version):
http://www.valuehobby.com/power-syst...ner-motor.html

Its lighter by 30 gms or so, and has a better price. My experience with G force motors has been good, and 2 other RCG'ers have told me the same thing.

Lower kv with larger prop means that it will have a lower top speed but will accelerate more quickly, powerfully. Something that suits gliders well. And its only going to be on 30 secs to climb...

Thoughts/opinions?
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Old Jan 30, 2013, 10:20 PM
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Originally Posted by coolgg View Post
I found this substitute by value hobby (850kv version):
http://www.valuehobby.com/power-syst...ner-motor.html

Its lighter by 30 gms or so, and has a better price. My experience with G force motors has been good, and 2 other RCG'ers have told me the same thing.

Lower kv with larger prop means that it will have a lower top speed but will accelerate more quickly, powerfully. Something that suits gliders well. And its only going to be on 30 secs to climb...

Thoughts/opinions?
Basicly my understanding and thoughts,, others correct me if I'm wrong : lower KV motors in same size equal lower amp draw but higher torque but lower rpms
So lower KV motor maybe more effecient for given torque but other factors in play also like drag of plane. So if I may highly overgeneralize,, the lower torque lower KV motor maybe a little more effecient getting to a particular altitude in a certain amount of time but higher KV motor may get you there more quickly, ALOT will depend on the precise motor prop combination used in each particular circumstance. Did I make that too complex???
The KV and size of that motor look good,, my only concern would be the motor wire placement and mounting in this tight front mounted application. The sailplane specific outrunner motors have wires either mounted in back out of the way of spinning motor can or,, as in case of the hyperion sailplane motor wires are mounted far away from spinning motor can . That's one of reasons I liked the E Flite BL25 motor cause even though its not SPECIFICALLY designed for sailplanes it is designed to be front mounted so wires are out of way of spinning motor can
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Old Jan 31, 2013, 09:18 AM
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Originally Posted by coolgg View Post
I found this substitute by value hobby (850kv version):
http://www.valuehobby.com/power-syst...ner-motor.html

Its lighter by 30 gms or so, and has a better price. My experience with G force motors has been good, and 2 other RCG'ers have told me the same thing.

Lower kv with larger prop means that it will have a lower top speed but will accelerate more quickly, powerfully. Something that suits gliders well. And its only going to be on 30 secs to climb...

Thoughts/opinions?
I think one of reasons that motor is lighter is it has a 4mm shaft as opposed to the 5mm shafts that most of these motors in this size,, I don't know if that's important or not,, just an observation
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Old Jan 31, 2013, 09:36 AM
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Going to a lighter motor will only save weight in the plane if you are placing weight in the tail or can remove weight from the tail. But if the plane balances properly with the heavier motor then you will have to make up that weight with lead in the nose, or a larger battery or something.

Saving weight in the nose often does nothing to save weight in the plane unless it allows you to take weight out of the tail too.

(this has been edited to fix a mistake that was pointed out later)

Save 30 grams in the nose and you need to take 5 to 10 grams out of the tail to balance.

If the CG is more forward than you wish, then saving weight in the motor might make it easier to shift the CG rearward AND make the plane a bit lighter too.
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Last edited by aeajr; Jan 31, 2013 at 12:11 PM. Reason: Correcting error on tail weight to nose weight ratios.
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Old Jan 31, 2013, 10:31 AM
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Originally Posted by aeajr View Post
Saving weight in the nose often does nothing to save weight in the plane unless it allows you to take weight out of the tail too. Save 30 grams in the nose and you need to take 75 to 150 grams out of the tail to balance.
Actually exactly opposite, 30g nose = maybe 10g in tail

Zb/Esprit Model
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Old Jan 31, 2013, 10:40 AM
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Read Light vs. Legs.
That was a good read...thanks for the link.
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Old Jan 31, 2013, 12:09 PM
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Originally Posted by Esprit Model View Post
Actually exactly opposite, 30g nose = maybe 10g in tail

Zb/Esprit Model
OOPS! you are exactly right. My mistake. I will go back and edit my earlier post so as not to confuse people.

Thanks for picking up that mistake.
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Old Jan 31, 2013, 12:37 PM
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Got my rudder and elevator linkages and servos hooked up and centered,got motor and prop installed and tested,, next up: the dreaded wing servos !! Yikes. :-O
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Old Jan 31, 2013, 02:36 PM
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Originally Posted by Airman74 View Post
Got my rudder and elevator linkages and servos hooked up and centered,got motor and prop installed and tested,, next up: the dreaded wing servos !! Yikes. :-O
The standard EFL25 was recommended as the model needs the nose weight, it is slightly heavier than teh YAK 25. You may have to add a ounce or 2 using QQ's motor however it should work fine.

I appreciate the exploritory nature of the soaring community, keeps me thinking :-).
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Old Jan 31, 2013, 02:46 PM
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Whats the weight of the E Flite BL 25 1000kv motor ?
Couldnt find the specs on horizonhobby or eflite's product page.
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Old Jan 31, 2013, 03:01 PM
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Originally Posted by coolgg View Post
Whats the weight of the E Flite BL 25 1000kv motor ?
Couldnt find the specs on horizonhobby or eflite's product page.
On my scale at least QQs yak 54 motor the BL25 weighed about 12 grams more than the reccomended power 25 870 KV I'm hoping that won't be too much additional weight in the nose maybe moving the battery a bit. Will get it,, or if I need more weight in nose I can always use the aeronaut spinner as its about 12 grams heavier than the e flite spinner,, I've got options!! Coolgg,, on my scale reccomended power 25 870 KV weighed about 187 grams and QQs power 25 1000kv weighed 200 grams,, it looks a little beefier too. In the yak we routinely use 4s pulling well over 800watts as measured by my wattmeter ,, so I don't think the 560-570 watts on 3S I'm measuring with it using 13x6.5 prop will hurt it. ;-)
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Old Jan 31, 2013, 03:03 PM
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Originally Posted by coolgg View Post
Whats the weight of the E Flite BL 25 1000kv motor ?
Couldnt find the specs on horizonhobby or eflite's product page.
Its a replacement motor for e Flites yak 54,, so I think it'll be hard to find exact specs on it
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Old Jan 31, 2013, 05:35 PM
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Originally Posted by coolgg View Post
I found this substitute by value hobby (850kv version):
http://www.valuehobby.com/power-syst...ner-motor.html

Its lighter by 30 gms or so, and has a better price. My experience with G force motors has been good, and 2 other RCG'ers have told me the same thing.

Lower kv with larger prop means that it will have a lower top speed but will accelerate more quickly, powerfully. Something that suits gliders well. And its only going to be on 30 secs to climb...

Thoughts/opinions?
Just looked at that motor again,, if that drawing with demensions are accurate then I'd say the bolt holes in front of motor have wrong spacing to be a drop in replacement I measured twice the center to center spacing on both E Flite motors at 18mm so that could possibly be a problem.
In their drawing they say center to center spacing of holes on that G Force motor at 15mm.
Guess you could always turn the motor a little and drill new holes,,, the yak motor is an EASY drop in install,, no shaft reversal, no hassle with motor wires,, and you saw Pete said it would work
Just be sure to use 13x6.5 blades cause the motor is higher KV , and it seems to be a VERY powerful motor
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