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First scrap build: the Funbat (questions)

teflyer

Full Circle
#2
well for the esc and the motor, I think that is fine. I don't think you meant to post the link for the 1500 HXT motor so many times. :)
 

Carbon

Elemental Madness
#5
alright, do you think a larger 3 cell will work as far as weight goes? how much time extra will say a 1000 mah give me?
 

colorex

Rotor Riot!
Mentor
#7
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Carbon

Elemental Madness
#8
Umm, looks like there are only two links...

But anyway, for that motor, the ESC is OK. Just notice that it is on backorder and that will delay your order indefinitely.

You could use the recommended props:

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=6225

Use 9 or 5 gram servos:

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=663

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=662

OK you say? is there a better option that will make the plane rock? like I said, I am just copying parts I've seen from other peoples stuff. Sorry so many questions, I just want to get it right before I buy anything.
 

teflyer

Full Circle
#9
a 10 amp ESC is okay for that particular motor because the motor only draws 7 amps on a 8x3.8 prop. f you want to continue scratchbuilding, I would go with a 15-18 amp ESC or a 18-20 amp ESC. How much does your model weigh as of now? and the 500 mah should be okay. You don't want to overload the ESC with too much current.
 
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Carbon

Elemental Madness
#10
I'm not quite sure what it weighs. It is a fairly small plane so it cant be much.
the motor will have enough power though? I don't necessarily want to hover or anything and I want it to be slow enough for me to fly. I do want to be able to climb quickly though.
for the esc, how about this:http://www.hobbyking.com/hobbyking/store/__6456__Hobbyking_SS_Series_15_18A_ESC.html

or, could I go with the suggested nutball parts and get these?
http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=2069&aff=247441
http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=18003&aff=247441
http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=10048&aff=247441
 
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#11
Yeah, it should fly as long as you used about 5mm foam and not overload with glue. the ESC looks good.
Now you can also use this battery if you want a little more flight time.

Turnigy 800mAh 2S 20C Lipo Pack (USA Warehouse)

Also, try to buy batteries from the US warehouse. I think that the batteries, since they are Lipos, have to get to the destination quick, so if you order it internationally, you will need to order it using EMS which is really expensive.
 
#12
ok so basically this is how I am determining what motor matches with which ESC with what battery. The motor has to draw equal or less current than the ESC can give. the ESC must be able to handle current equal to or greater than that of the battery. How you know how much current the battery outputs, you multiply C rating by the Amp-Hours or multiply the C rating by the miliAmp-Hours and divideby 1000. Essentially the same thing. The two different numbers on the battery for C ratings that shows up sometimes represent the C rating the battery normally ouputs and the C rating for a burst. How to calculate flight time is by dividing the Amp Hours by the amount of Amps being drawn and that gives you how many hours it will fly. Of cours that is with a perfectly efficient setup and since that never happes, you have to subtract a little time.
 

colorex

Rotor Riot!
Mentor
#14
for the battery, what does 2s mean?
Lipos are individual cells paired up and connected in different ways. 2S means two cells, two cells in series.

Each cell has about 3.7 volts in it. A 1 cell lipo would have 3.7 volts. A 2 cell lipo would have 7.4 volts. A 3 cell lipo would have 11.1 volts. A 4 cell lipo would have 14.8 volts. And so on.

Higher voltage means a faster motor. But you need to stay within the acceptable range for the motor.
 

Carbon

Elemental Madness
#16
thanks colorex. this thread has so far cleared just about everything up for me. if I am using a 2 cell, should I scale down the esc to save weight?

EDIT: if I choose to change to a 3 cell battery later on, will it affect the motor/esc?
 

colorex

Rotor Riot!
Mentor
#17
thanks colorex. this thread has so far cleared just about everything up for me. if I am using a 2 cell, should I scale down the esc to save weight?

EDIT: if I choose to change to a 3 cell battery later on, will it affect the motor/esc?
Well, all the ESC's I have learned to trust are out of stock - the Turnigy Plush and Turnigy Basic series. I would have recommended this one, but it's out of stock.

http://www.hobbyking.com/hobbyking/store/__4312__TURNIGY_Plush_18amp_Speed_Controller.html

Here is the other option that IS in stock; it's a 25 Amp, but more reliable than the Red Brick:

http://www.hobbyking.com/buddy.asp?code=5FB0AF2B-7046-4900-9A7F-AA9421FA7BF4

No need to get a smaller ESC. Getting a bit more capacity is good because then it will run cooler.

---------------

If you choose a 3 cell battery later on, you'll need to upgrade your motor to a 3S capable one (24gram 1300kv), but you can still use the rest of the stuff.
 
#18
You can keep the same ESC if you want but you can scale it down to a 15-18 amp ESC for a 700mah battery or to a 10 amp ESC if you are using the 500mah battery. If you notice the ESC has a certain range of volatage it works on.That is the only limitation on battery in terms of voltage. Current, however, is slightly different as shown above in oneof the previous posts
 

colorex

Rotor Riot!
Mentor
#19
The Turnigy Basic 25 Amp ESC posted above will give you expansion possibility, I have even used one of those in my Bixler. It has 2-4 cell capacity, so that shouldn't be a problem.

The following buddy code link should give you a small discount: (Log into HobbyKing before clicking it)

http://www.hobbyking.com/hobbyking/...uddycode=5FB0AF2B-7046-4900-9A7F-AA9421FA7BF4

---------------------------------

Remember that ESC's come without connectors. You might have to buy some of those. Sorry, but I can't help you here, as I haven't used those small red connectors.
 

pgerts

Old age member
Mentor
#20
I have about 10 minutes normal flight with 2 cell 400 mAh.
A 3 cell 850 mAh will fit fine with a 7" prop but then you might want to upgrade the motor and esc to
http://www.hobbyking.com/hobbyking/store/__4713__TowerPro_BM2409_18T_25A_BEC_8x3_8_Prop_Combo.html
and also add some more weight as reinforcements of the wing and from part of the plane.

With the 25 gram 2 cell 400 mAh you will fasten the battery with welcro in front of the wing but with the bigger motor and esc you will put the battery in the body under the wing.

There is not o lot of space in the body for a big RX and battery.