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Old 04-10-2012, 09:22 AM   #1
Swanj
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Default Recommended motor & RPm for a flying wing

I need a little advice pse.I'm sort of a newbie not being too familiar with rc motors.I have built a hot wire foam cutter and am intending to make a flying wing.It will have about 40" wing span,but am not too sure of iits weight.I intend on using a 3 cell 2200mah battery! Can anyone recommend a good motor for it and motor size. I understand it must be high Rpm also.I would like to use a Turnigy motor since they are fairly cheap. I would like to see between70and 90 mph if possible.Of course I will buy a brushless. Can anyone recommend a motor size and Rpm for my flying wing?
Thanks anyone!
SwanJ.. calif...

I may not be the best at what I Do! But, if I try my best, I certainly won't be the Worst !
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Old 04-10-2012, 04:35 PM   #2
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Hello, and welcome to R/C flying.

1) You NEED the final weight to determine what motor you will need.

2) You NEED experience BEFORE you fly ANY airplane that will go 90mph

Is this a serious post? I can tell you for sure that if this is your first R/C aircraft, you WILL quickly crash. A flying wing, in particular one of this speed, will require first learning to operate a trainer airplane safely.

Maybe I'm taking the newbee part wrong.

With all that said, I have a wing of about that size and an all up weight of 16.5 ounces using this motor....flies great. I'm using an APC 7/6 prop. This is about a 210 watt setup which is over the motor limit, but hey, it is a $10 motor with lots of cooling. No problem with over 100 flights.

http://www.headsuprc.com/servlet/the...ushless/Detail

Cliff
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Old 04-10-2012, 05:59 PM   #3
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Default Recommended Motor for flying wing pwr&Rpm

Hi Chiffl..
Thanks for the information and also the link to the-max CF 2812 motor.Yes Iam serious ! I've been flying for about 2 yrs now. an F4u cosair and a t-28 trogan.. planes I have purchased have always came with the stock motors. they were always 480's in size.I just built a foam cutting table and wanted my first foamie to be a flying wing. So, not being to familliar with RC motors, I didn't know what exact size and rpm of motor I needed. I assume my finished wing will weigh approx the same weight as yours.15 oz or so. My only problem will be determining the CG,wich will be determined on its maiden flight. Since our flight strip has plenty of high weeds that I will launch over in case of an immediate nose in, it won't be damaged so much. Thank heavens for the tall weeds, since they have saved many a crash with no bad damage, etc.I have plenty of ESC's and servos, so the motor will be the only thing I will have to purchase for the wing.I am a retired carpenter of 45 yrs , so making the wing templets won't be any problem! so Thanks for the link and advice there Cliffl..
Appreciate it much, there fella!

Swanj.. Calif

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Old 04-10-2012, 06:23 PM   #4
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Okay there Swanj, I guess I had overestimated your "newbie" staus

The starting CG should be about 1/3 back fron the leading edge at the "point" of the wing, or the root. Like all planes, moving back gives more manuverbility, moving forward is more stable.

90mph will require a higher kv motor than I have suggested here, but this motor is still very fast with a 7x6 prop, and it is cheap.

Expect about a 20 amp draw with a 3S lipo, so get a 30C 1,300mah (around this anyhow) battery for long life.

Have fun!

Cliff
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Old 04-10-2012, 10:53 PM   #5
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Default recommended motor& rpm for flying wing

Ok Cliffl

Thanks again for the info.Well! I really feel like a Newbie, since I surffered a minor stroke back in June.It sure hasn't helped my orientation at all I sure have had my share of crashes.I'm sure 1100kv is fast enough for me.I can always upgrade to a larger KV if I want. I fabricate my own motor mounts, etc, so experimentation with different motors is no sweat. Thanks for the cg measurments.I'm sure that will get me in the ball park for my first launch.

Ta Ta and take care there Fella!
Swanj.. calif where the weather has been like spring all winter long. Nice for flying,and no hazards of meeting Rattle Snakes while retrieving crashed planes in the high weeds.thats the only downfall of where our flight strip is located.

I may not be the best at what I Do! But, if I try my best, I certainly won't be the Worst !
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Old 04-10-2012, 11:20 PM   #6
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This wing CG calculator has worked for me several times.
http://fwcg.3dzone.dk/?wing_span=38&...ow_mac_lines=0
When you click in the boxes a line will appear showing what to measure.

HK is becoming a pain. HeadsUpRC gives service, fast cheap shipping, AND support + information. Either of these motors (for the pusher Easy Star) will work fine:
http://www.headsuprc.com/servlet/the...R--dsh-/Detail

fly
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Old 04-11-2012, 02:38 AM   #7
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With a 6x5.5 on 3s this might get you to 90mph: http://www.graysonhobby.com/catalog/...tor-p-585.html

but you'll need 400W+ to get that sort of speed with a 40" wing.
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Old 11-14-2012, 09:10 AM   #8
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you want a hk funfighter brushless 2825kv motor. turnigy 4s 1000 nanotech battery. apc 5x5.5 prop 20amp esc, hxt900g servos. 100 plus easy. build it like a usa tuffwing with spars, lots of tape on nose and wing edges and coreflu box(property sign). mount servos on top on their side. set the elvons to point up slightly by sight. elvon movement 9mm up 9mm down set . rates so you have 100% movement> lots of stick movement little action< find a big wide open park, slight breeze ok. if it dives when launching give elvons more up....any one can fly these even without experience.just dont go full throttleuntill you are used to it or pointing straight up? Its the settings that will distroy it more than you. once in the air you can cruise or scream around....Height is your friend?
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Old 06-14-2014, 09:11 PM   #9
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Hi,
I dont mean to hijack your thread here but I thought this could be constructive. I have been looking to build a FAST flying wing. I have chosen the "Flitetest Versa wing" which has a 38" wingspan. I built one for a friend, it just went together so well I decided to cut out another one for myself.

So here's my question:
I have been looking at some very high kv motors (3900kv). For a 16-17 oz. wing, what watt motor should I use? Will such a high kv motor even work on a wing? I intend to run on a 2200mAh 3s or possibly even 2 in parallel.

The wattage of the 3 motors i have narrowed it down to are 220w, 300w, and 400w. I guess it all depends on how long I want to fly because each one will make this thing a rocket-ship!!

220w:
http://www.hobbypartz.com/96m04-car-2040-3835.html
300w:
http://www.hobbypartz.com/96m270-2838-3900kv-17t.html (My first choise!)
400w:
http://www.hobbypartz.com/96m31-car-2848-3900.html

Thanks guys,
Pat
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Old 06-16-2014, 03:11 AM   #10
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http://www.headsuphobby.com/Power-Up...otor-E-610.htm

my reccomendation. 2950kv, 108mph on a fun jet. should fly on 3 cells and a flying wing, plus with $2 shipping and great customer service.

That motor is capeable of 600 watts on 3 cells, and if you get bored with it, you could always try it on 4 cells.

good luck, and let us know how it goes.

slow stock prop reversal. it flies! easily! 543 watt dual motor bipe slow stick. push-me-pull-you. 242 watt 3 channel slow stick. 365 watt mini ultra stick. 415 watt mini contender. 810 watt ultra stick .25e. 220 watt alpha 450 sport (retired).
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Old 06-16-2014, 12:46 PM   #11
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Hi there Hayofstacks,
I've been reading up on some forums and read somewhere that a lower kv will actually be faster than the 3000+ kv because it can over power the airframe drag better. So I set my search for slightly lower kv and found a sweet looking turnigy motor.

http://www.hobbyking.com/hobbyking/s...dproduct=18117

I was thinking this on a 6x5.5 - which still has a prop speed of 144 but also more torque to get me there. 600w seems a little much for my application; i was going for a high powered (fast) wing for FPV but also fun to fly LOS. Im putting this motor on a FT Versa wing and 400w is more than enough!!

-Pat
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Old 06-16-2014, 02:38 PM   #12
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Originally Posted by Rotor_Freak_RC View Post
Hi there Hayofstacks,
I've been reading up on some forums and read somewhere that a lower kv will actually be faster than the 3000+ kv because it can over power the airframe drag better. So I set my search for slightly lower kv and found a sweet looking turnigy motor.

http://www.hobbyking.com/hobbyking/s...dproduct=18117

I was thinking this on a 6x5.5 - which still has a prop speed of 144 but also more torque to get me there. 600w seems a little much for my application; i was going for a high powered (fast) wing for FPV but also fun to fly LOS. Im putting this motor on a FT Versa wing and 400w is more than enough!!

-Pat
Not sure where you getting your more torque idea from. The power up motor recommend has higher amp rating than that sk3. Higher amp rating at the same voltage simply means you can fly it with a bigger prop. It's not that a motor has lower kV that allows it to overcome drag better but it is because a lower kV motor can ( usually ) handle a bigger prop. Bigger prop equates to more thrust. It's that extra thrust that does the work.
Keeping that in mind, the power up and sk3 are both capable of running the same prop. The power up can handle more power at a higher kV. That means that with the power up motor you will go faster and with more thrust.
Trust me when i say that you will be much happier with the power up from hurc.
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Old 06-16-2014, 07:45 PM   #13
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I read the faster torque thing on a rcgroups forum. It makes sense if you think about it:

If you have an airframe that has x amount of drag and a 3900kv motor on it, the motor has the capability to go faster, but not enough torque to accelerate it past a certain speed barrier (basically a semi-stalled prop). If you have the same airframe with a slightly lower kv motor (say 3000-3500) of the same power and same pitch prop, it will have more torque to get the airframe past that barrier you were hitting before.

I guess it is a specific situation but It may have some truth to it.

Anyway, I am concerned about flight time on the wing as well. Would that power up 600W allow me to fly 2x 3s packs in parallel? AUW would be close to 19 oz. with one battery and 26 oz. with two. It is a 38" wing with a moderate chord.

I calculate at about cruising throttle, I would get about 4 min on a single 2200mAh and obviously about 8 min on 2x 2200mAh.

Thanks so much for your help!!

-Pat
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Old 06-16-2014, 09:34 PM   #14
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You can also get more thrust and lower the pith speed to give you the exact same results...

a larger motor spinning a larger prop is more efficient then a small one screaming away. you also have a throttle. your not going to use 600watts unless you want to. more likely then not, you will be under half throttle and using less then 300watts the majority of the time your flying. then if you feel the need, you hit the throttle.

prop down when you want a long flight time, if you don't want to fly as fast because your worried about stalling the prop, prop down. use the prop that suits your flying style and the plane best.

with 38+ oz of thrust and over 100mpg pitch speed and 16-20oz of weight, you'll have no problem surpassing 90mph.

slow stock prop reversal. it flies! easily! 543 watt dual motor bipe slow stick. push-me-pull-you. 242 watt 3 channel slow stick. 365 watt mini ultra stick. 415 watt mini contender. 810 watt ultra stick .25e. 220 watt alpha 450 sport (retired).
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Old 06-16-2014, 09:36 PM   #15
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Btw, my dad has a 32" wing on a 1300mah battery pulling over 400watts and it flies for over 8 minutes with average throttle and weighs more then 20oz due to tape and repairs. I'm sure your plane would fly fine on the heads up motor i linked to.

slow stock prop reversal. it flies! easily! 543 watt dual motor bipe slow stick. push-me-pull-you. 242 watt 3 channel slow stick. 365 watt mini ultra stick. 415 watt mini contender. 810 watt ultra stick .25e. 220 watt alpha 450 sport (retired).
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Old 06-16-2014, 09:45 PM   #16
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Also, the auw ive seen for a funjet are all around 20oz, and i ASSume the funjet is a much draggier airframe then just a flying wing. think of the thrust as torque and the pitch as speed. if your plane can't handle the pitch, then prop down a size and try again.

slow stock prop reversal. it flies! easily! 543 watt dual motor bipe slow stick. push-me-pull-you. 242 watt 3 channel slow stick. 365 watt mini ultra stick. 415 watt mini contender. 810 watt ultra stick .25e. 220 watt alpha 450 sport (retired).
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Old 06-16-2014, 10:16 PM   #17
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Great!! Thanks for all your help, I only have a couple planes right now; Im more of a heli guy (you'd never know by my username ).

Im ordering the 600w right now!!

Thanks again,
Pat
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