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Author Topic: alternative motor for PF 1/2 A ?  (Read 1057 times)

Offline Vincent Corwell

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alternative motor for PF 1/2 A ?
« on: February 17, 2011, 01:06:32 AM »
What is the Turnigy ( cheap ) equivalent to the Arrowind 2210-25......1560KV motor please ?

intended for the Pathfinder 1/2 A airframe

thanks in advance

Vincent
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Offline Mike Anderson

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Re: alternative motor for PF 1/2 A ?
« Reply #1 on: February 17, 2011, 08:32:45 AM »
Quote from: Vincent Corwell on February 17, 2011, 01:06:32 AM
What is the Turnigy ( cheap ) equivalent to the Arrowind 2210-25......1560KV motor please ?

intended for the Pathfinder 1/2 A airframe

thanks in advance

Vincent

This one is pretty close:

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=5655

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Mike@   AMA 10086
Central Iowa

ChrisSarnowski

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Re: alternative motor for PF 1/2 A ?
« Reply #2 on: February 17, 2011, 10:02:03 AM »
That was my guess too, the C28-26 1650kv.

I also noticed an EMAX motor that looks right on EMAX BL2210/25 1560KV Outrunner

You can search for that on Ebay or where ever.

-Chris
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Offline Vincent Corwell

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Re: alternative motor for PF 1/2 A ?
« Reply #3 on: February 17, 2011, 03:35:18 PM »
Thank you, that takes me a step nearer

Vincent
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Offline Andrew Borgogna

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Re: alternative motor for PF 1/2 A ?
« Reply #4 on: February 18, 2011, 12:04:22 PM »
I too have a 1/2a pathfinder that is setup to fly electric.  I really don't think any 1/2a equivlent motor with fly the plane.  I have a 135w motor and would not want to fly the plane on anything less.  This is more like a .09 size IC engine. 

If you follow Larry Renger's conversion equation.  .061ci x 1.5(hp/ci)=0.0915hp / .8(for 80% efficiency)=0.114375hp x 746(watts per hp)=85.3watts.  Add in 10% loss for prop and you will need 93.8watts to equal a .061 1/2a engine. 

Maybe you can build a 1/2a Pathfinder light enough to fly on a 94watts, I can't.  If you take Larry's equation an insert a .09ci you get you get a 138 watts.  I am worried that mine will fly on 135 watts. If I ever get a chance to fly it I will let you know how things go.  I would like to go to a 150watt motor, but then the battery needed to fly a 5 minute pattern becomes a problem.  Oh well.
Andy
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Andrew B. Borgogna

Offline Larry Renger

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Re: alternative motor for PF 1/2 A ?
« Reply #5 on: February 18, 2011, 10:16:28 PM »
Actually, big stunt engines do 2 hp/c.i. and the small ones more like 2.5, not 1.5.  The Tee Dee .09 pumped out 3!  I suspect a Cyclon or other ultra performance motors run about 5 hp/c.i.

So, let's try that one again:  .061x2.5=.1525 hp  that, divided by 80% is .190 hp.  that comes to 142 Watts,  give another 10% for prop loss and you need IN FLIGHT power of 158 Watts.

My (only) data shows a drop to 77% from ground drain to flight; so that means a ground power drain of 205 watts!

Now 158 Watts for 4.5 minutes comes to ( 158Volt-Amp*.075Hour/11.5Volts ) 1.03 Amp-Hr.  We only want to use 80% of the pack capacity, so we need a 1300mAh 3s pack to complete the pattern.

Hope that helps!   (051)
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Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan
 BTW, Dracula Sucks!  A closed mouth gathers no feet!

Offline jim gilmore

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Re: alternative motor for PF 1/2 A ?
« Reply #6 on: February 19, 2011, 08:56:42 AM »
The term 1/2A is a misnomer.
But then again so is most of the terms used to quantify engine size.
While the 1/2A p/f is considered 1/2A I do not think of it as a true 1/2A. No babe bee or golden bee on missle mist or dukes fuel would have flown it. Though I often flew a baby ringmaster covered with nylon,and powerd by a golden bee on 25-30 foot cotton lines.
It flew loops and eights easily.
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Offline Andrew Borgogna

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Re: alternative motor for PF 1/2 A ?
« Reply #7 on: February 19, 2011, 01:06:07 PM »
Larry
Why for you no tell me the new data regarding ci to hp kimo-sabbie?  Now I am really scared about my pathfinder.  The motor I have has a continues amp rating of 12 amps.  That times 11.1v is 133 watts.  I can run my motor at 200 watts but it won't last very long.  Oh well it was cheap.
Andy
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Andrew B. Borgogna

Offline Larry Renger

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Re: alternative motor for PF 1/2 A ?
« Reply #8 on: February 19, 2011, 02:35:17 PM »
What does the PF weigh ready to go?  It should fly just fine on a .049 up to 12 ounces and an .061 up to around 15 ounces.  Adjusting line length can make up for a lot of power differences.  It will certainly go around in circles just fine, and we can work with it from there.

All we need now is some clear weather!
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Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan
 BTW, Dracula Sucks!  A closed mouth gathers no feet!

Offline Andrew Borgogna

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Re: alternative motor for PF 1/2 A ?
« Reply #9 on: February 20, 2011, 12:07:27 PM »
Larry
My PF has an all up ready to fly weight of 17ozs.  It is built as light as I can make an airplane.  The battery weight is 4.4ozs alone, it has clear dope only and the lightest wheels possible.  You have seen the plane, heck you gave me the uncovered frame, you know how light it is.  I believe it would fly great on a IC .061, I am just not sure it will fly with the current power package.  I have ordered an arrowind motor just like the one Dennis is flying in his just in case.
Andhy
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Andrew B. Borgogna

Offline Larry Renger

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Re: alternative motor for PF 1/2 A ?
« Reply #10 on: February 22, 2011, 09:49:14 AM »
All is not lost!  ;D  A good measure of performance potential is calculated by:   k = weight/ ( wing area * wingspan)

Your pathfinder works out as:  k = 17/(236*35) = .00205

You remember my baby Nobler?  It flies and corners just fine with k = 11/(160*28) = .00246

The smaller the k, the better the flyer!

Of course my new Sky Streak comes out at k = 6.7/(250*35) = .00077  but who's counting?   VD~
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Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan
 BTW, Dracula Sucks!  A closed mouth gathers no feet!

Offline Andrew Borgogna

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Re: alternative motor for PF 1/2 A ?
« Reply #11 on: February 22, 2011, 11:15:42 AM »
Aint it great to have a friend who when to MIT!!!  Thanks Larry, see you tomorrow.
Andy
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Andrew B. Borgogna

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