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transmitter, receiver, ESC, engine, battery, servos...

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transmitter, receiver, ESC, engine, battery, servos...

Old 03-01-2007, 07:32 AM
  #1  
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Default transmitter, receiver, ESC, engine, battery, servos...

One simple question.
How do I know what will work with what AND how do you connect them all together?
I guess thats really two questions
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Old 03-01-2007, 09:20 AM
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Okay, I am assuming you mean moter not engine

So basicly, pretty much all things are compatable, but you must whatch out for this:
1: Esc and moter must be matched, if you put to much power into the ESC you will blow it.
2:Athough not necisary, it is desireable to get parts of the same brand, because this eliminates the problem of having lots of different connecters, if you want to replace the conecters, Deans connecters are a good choice.

That is all that comes to mind, maby some of the experianced guys will post with some ideas.

PS: Pls Exuse the spelling
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Old 03-01-2007, 01:14 PM
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There are 2 major differences in radio gear. Futaba and Hitec are negative shift as a rule. And JR and Airtronics are generally positive shift. Watch out for this if you are going to buy your pieces seperate.

What gear are you looking at and it will be easier to tell you if it will work. There's way to many combo's to list.
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Old 03-01-2007, 03:23 PM
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Everything works together if you've bought the right stuff . Maybe ask some slightly more definite questions.

BTW the negative vs positive shift thing for radios only applies to 72MHz gear i.e. mainly North America. If you're anywhere else in the world you're probably o.k. mixing all makes of radio equipment.

Steve
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Old 03-01-2007, 04:42 PM
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Originally Posted by BatteriesIncluded View Post
One simple question.
How do I know what will work with what AND how do you connect them all together?
I guess thats really two questions
That is not a simple question and one that cannot be answered with out more information. There are literally thousands of combinations of the items you mentioned that will work together. Then of course you have to consider the propeller and airplane used with the items you mentioned.

If you are a beginner and are looking for a starter airplane, I would suggest that you purchase one that has all those questions answered for you.

If you have a specific airplane in mind, let us know and folks will be able to give suggestions. There are several threads on WattFlyer and RCGroups in the beginner areas that will help answer your questions in a general sense.

Provide some more info and folks can help.
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Old 03-01-2007, 09:58 PM
  #6  
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Same thing I wondered a few weeks ago. I'm starting to get an idea because after having an RTF I jumped in headfirst with a scratchbuilt foam plane and all of its electronics.

If there is a simple how-to that explains all the parts in sufficient detail for a newbie to explain, I've not seen it.

That's why once I'm finished my plane within the next several days I plan on making just such a guide with good images and labels and explanations of things so that a person who does not know anything about this can get a jump start I didn't have!
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Old 03-02-2007, 01:17 AM
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Is that your silver STC on RCG I seen under JWilliams2? That's one good lookin' bird.
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Old 03-02-2007, 03:39 AM
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Originally Posted by smokejohnson View Post
Is that your silver STC on RCG I seen under JWilliams2? That's one good lookin' bird.
That's it, hopefully it will stay looking decent once I've finished hacking the motor on etc. thanks!
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Old 03-02-2007, 05:45 AM
  #9  
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Originally Posted by Rabbitcreekok View Post
That is not a simple question and one that cannot be answered with out more information. There are literally thousands of combinations of the items you mentioned that will work together. Then of course you have to consider the propeller and airplane used with the items you mentioned.
I realize it's really an open ended question. I'm sure many of you could bedazzle us newbies enough to make our heads spin on this subject. I'm kind of looking for generalties in what to look for as I learn all of the electronics. Things like 72MHz negative/positive RX and TX are really helpful. Sticking with the same brand is also a sinple way to avoid problems
and checking motor/prop combos helps also.
BUT, In reality, I have not often seen anyone using all of the same brand electronics in their planes so that tells me there are things to look for that would give me an idea of what works with what. Hopefully, if enough of you leave tidbits of wisdom here it may gel in our little newbie brains to help us figure all of this out.
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Old 03-02-2007, 05:46 AM
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Originally Posted by JWilliams View Post
That's why once I'm finished my plane within the next several days I plan on making just such a guide with good images and labels and explanations of things so that a person who does not know anything about this can get a jump start I didn't have!
Now that would be cool!
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Old 03-02-2007, 05:52 AM
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Originally Posted by smokejohnson View Post
There are 2 major differences in radio gear. Futaba and Hitec are negative shift as a rule. And JR and Airtronics are generally positive shift. Watch out for this if you are going to buy your pieces seperate.

What gear are you looking at and it will be easier to tell you if it will work. There's way to many combo's to list.

What about those Corona receivers (RS410, 610, 810) that claim
"It auto-detects the positive
or negative shift, and is available with most transmitter, including
Futaba, JR, Hitec, SANWA, GWS, MULTIPLEX. RS410 uses UM-5 or
UM-1, which is a very small single conversion receiver crystal."

Is this for real? -> http://www.corona-rc.com/index.php?o...d=15&Itemid=33

Last edited by BatteriesIncluded; 03-02-2007 at 05:53 AM. Reason: added link
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Old 03-02-2007, 06:27 AM
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It's for real. I don't know anything about the Corona's but I use a Berg that does the same thing. http://www.castlecreations.com/products/berg_ms4l.html

Work's great for me and I like that they have a flat rate for repair or replacement if you damage their products.
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Old 03-02-2007, 06:27 PM
  #13  
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Regarding the transmitter, receiver, and servos, for a beginner the best thing to do is buy them as a set. You can commonly get a set with Tx, Rx and 2 servos. The servos do have to be matched to the plane: big enough to operate the control surfaces but not too heavy for the plane. For typical parkflyers up to about 16 oz weight, sub-micro servos like Hitec's HS-55 are a good match. For larger or faster planes Hitec's HS-81 are good. Other manufacturers have their own servos in the same basic size classes. So my advice would be to buy a combo (and any additional servos you need) from one manufacturer at first, then keep reading these forums and talking to people and you will learn an awful lot very quickly.

With that said, I've also used a couple of the Corona receivers with my Hitec Tx and they have been flawless.

Now on to the power system. This is basically independent from the radio/servos, with one exception. The power system consists of the motor, ESC, and battery. In selecting the ESC, you do need to make sure that your ESC can handle the number of servos you will be using. ESCs usually have user manuals available on line and you can look up how many servos your ESC can handle. Actually these ratings are usually conservative - if it says 3 servos you can probably use 4 as long as you aren't flying so aggressively that you are using all 4 servos at once.

Now here's everything else you need to know (well, everything I know anyway) about matching power systems:

Brushless DC Electric Power

Primer on Electric Terminology
Volts are a measure of electric “pressure”. Amps are a measure of current, or electric “flow”. Watts = volts x amps. Watts are a measure of power. What you really care about for airplane performance is watts, but to get watts you need to figure out the amps and volts.

What Determines How All These Things Go Together?

• Voltage is determined by the battery. Voltage and the motor’s Kv rating determine the no-load rpm. The motor will try to achieve that rpm even under load. It won’t succeed but will keep trying.
• The propeller diameter and pitch, plus model weight and speed, determine how hard the motor has to work, or how much power (watts) it has to produce, to try to reach that rpm.
• How hard the motor has to work, plus losses in the motor, ESC and wires (they are not 100% efficient), determine how many amps of current the motor will try to pull from the battery. Ideally, the motor will turn the prop at a speed that is enough to fly the airplane well without pulling enough current to overheat itself or exceed the current capability of other components.

The Power System Selection Process:

• Consider the plane’s weight, drag, desired speed and your expected flying style. Size the motor and select a battery voltage using the rules of thumb below. Size the ESC and battery to handle a little more current than the motor. Then choose the prop to stay within the motor’s current limits.

Sizing The Components:

• Rough rule of thumb #1: 4-7 watts per ounce of aircraft weight will fly a trainer adequately. 10-15 watts per ounce will fly a 3D aerobatic plane, sport plane or scale warbird. 15-20 watts per ounce will fly a fast prop jet or flying wing. Speed/power freaks will naturally want more. Both low-speed thrust and high top speed require power. All else being equal, increasing speed requires more power than increasing thrust.
• Rough rule of thumb #2: a brushless motor can handle 80-100 continuous watts per ounce of motor weight. High quality motors are at the high end and cheap motors are at the low end. Low speed, high-torque motors (700-950 Kv) are best suited to high-thrust low-speed or high-drag planes such as trainers, 3D aerobatic types and biplanes. High speed motors (1500-5000 Kv) are for ducted fans, prop jets, flying wings and similar types. Intermediate speed motors (950-1500 Kv) are for general sport planes, scale WWII fighters and the like. High speed motors and higher pitch props will draw more current than low speed motors and low pitch props.
• For most planes with brushless motors, the sweet spot in voltage is 8-12 volts. This is a 7-10 cell NiMH or a 3s LiPo battery. For small planes with moderate performance or if weight and cost are critical, a 2s LiPo or 6-cell NiMH is often enough. For bigger planes – larger than about 2-3 lbs - or very fast planes, more volts are called for.
• Brushed motors in general can’t handle as much power per ounce of motor weight. Not sure of their limit – maybe 50-70 watts/ounce?

So figure out how many watts you need. Choose a battery type and voltage. Divide the watts by the volts to get amps. Then choose a motor with the right Kv for your type of plane and a sufficient amp rating. Choose an ESC with an amp rating slightly higher than the motor's. Choose a battery amp capacity (mAh x "C" rating) that is also a little higher than the motor's. Last, choose a prop that will keep the motor within its amp rating. Search the forums for a review of your motor or check the manufacturer's web site - some of the best ones publish actual test results with different props. Some publish calculated data - this is not as reliable.

Reaching the Limits:

• Motor Size: If the motor is just too small for the plane, and the prop, battery and ESC are well matched to the motor, the whole system simply won’t produce enough power to fly the plane well. The motor needs to be upgraded, along with any other components that don’t have excess capacity.
• Motor Heat: If the motor can’t reach target rpm with the prop that is on it, it continues to try to pull more current. Up to a point, this is normal and good. Beyond a certain point (too big a prop), the motor produces heat faster than its metal parts can radiate it away. The motor overheats. Note – the heat produced due to motor inefficiency is proportional to amps, not watts as such. Increasing voltage will not increase heat directly, though increasing voltage does increase rpm, and that increases hysteresis and eddy current losses. At outrunner speeds this is not significant and only amps really matter.
• Battery Current Limit: The battery may not be able to generate all the current the motor tries to draw. Battery voltage will drop, and the battery may overheat. The motor doesn’t reach target rpm and the system doesn’t produce the expected power. Battery life is shortened.
• The ESC may not be able to pass all the current being drawn by the motor, or insufficient supply from the battery may affect the ESC’s capacitors. The ESC may overheat and shut down or be damaged.
• The wires and connectors may not be able to pass all the current being drawn by the motor. The wires may overheat, or may just limit the power reaching the motor. This can be caused by wires being too small, connectors being too small or not connecting firmly, or by bad solder joints.

Solutions:

• Change to a smaller diameter or lower pitch propeller, and live with less thrust or speed than expected. This will probably improve the system’s actual performance vs. the overloaded system, though maybe not to the point that you originally expected.
• Replace the battery with one of higher voltage. That will allow the same power with lower current draw, resulting in less heat. Or it will allow more power, since more volts help supply the current the motor is trying to pull. If you do this, also switch to a smaller prop until you are sure the motor and ESC can handle it. You can always put the bigger prop back on later.
• Make sure there's airflow over any part that is overheating. Make sure air can get both in and out. If necessary, cut holes in the fuselage to let air in or out.
• Replace whichever component is overheating with one of higher capacity. Then check the other components to make sure they are still sufficient.
• Make sure all connectors are rated for the amperage being passed through them. Check the condition of all connectors and solder joints.
• Flying technique affects the current draw. The motor will draw more current when the plane is climbing, the propeller load increases and the rpm drops. It will draw less current when the plane is flying level or diving and the motor can speed up with less effort. The maximum current draw occurs when the plane’s forward speed is zero, such as in a hover or at takeoff. If your system is marginally OK, it might help just to avoid hovering-style maneuvers and extended steep climbs.
• The ESC may allow different timing. Timing can be set to “soft” to reduce power and current draw.
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Old 03-03-2007, 02:14 AM
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Thanks Tom! Awesome Post! I appreciate the effort and time you took to share your knowledge in a way that someone new to this could understand. This post has really cleared up alot of the mystery of putting together power and electrical systems for me. I'm going to cut and paste your post into a word document to use as a reference later. For now, I think I'll stick to flight packs and sets until I get more practical experience and read more here on the forums.
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Old 03-03-2007, 03:58 PM
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Next Step?
Once you have your motor, propeller, ESC, battery, servos, and receiver chosen it all has to be put together. Most of the components come with good enough instructions to figure out how to connect things together and what channels on the receiver to use for ESC and servos (depending on your TX - negative or positive shift).

My uncertainty is about connectors rather than connections, so here goes.

To connect the ESC to the battery it seems that Deans ultra connectors (polarized) are the most popular. Does this mean that I have to change the stock plug on the battery to accomodate the ultra connector? For instance, say you have an ESC rated for a 2 cell LiPo battery. These batteries come with a JST connector. Will this connector fit in the ultra or do I need to change whats on the battery? OR... is there an adapter or extension that fits between the two? Can I solder a stock JST connector onto the ESC instead?

To connect the motor to the ESC, I've noticed that what is most popular for brushed motors is to solder the wires from the ESC directly to the motor or use a non-polarized ultra connector. For brushless everyone seems to go with banana plugs. I have a brushed motor EPS 350 with D gear that already has a connector on it. Do I cut this connector off and use the wires to solder it to the ESC wires? If I want to use components like ESC or a motor in another plane should I then cut off the connector on the motor and install ultra (non-polarized) to both the motor and ESC leads? Can I use bananas on brushed motors. HEY, Whats the best option here?
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Old 03-03-2007, 05:22 PM
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You can use whatever connectors you like. There is no "best option", everyone has their own favourites. And if you fly a reasonable range of models you'll find that it's not sensible to try to do it all with just one type of connector. For example :

For ESC to battery I use BEC/JST connectors for very small indoor stuff less than about 3A, 2mm gold connectors (they're not really banana plugs) up to about 20A and Powerpoles (Sermos) for over 20A.

For motor to ESC I mainly use 3.5mm gold connectors, because lots of the motors I like have them fitted as standard, or I solder direct depending on what the motor and ESC are and what I feel like at the time. And sometimes for small brushed motors like GWS IPS motors I stay with the BEC/JST connectors on motor to ESC simply because they're fitted with them as standard.

Steve
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Old 03-05-2007, 03:26 PM
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When does one use a BEC? This is somewhat confusing to me. Does a BEC replace an ESC or do I need both a BEC and an ESC?
I have the folowing:

Receiver = Corona RS410 RX http://www.bphobbies.com/view.asp?id...1&pid=A3067642

ESC = Blue Arrow 15-Amp ESC for Brushed Motors / 2-Cell Li-Poly (BA-PP-15B)
http://www.bphobbies.com/view.asp?id...06&pid=U723171

Motor = EPS-300C-2S/BB (2.80:1) Power System (GW/EPS-300C-2S/BB)
http://www.bphobbies.com/view.asp?id...41&pid=T257344

Servos = HS-55 Servo (31055S) Hitec/JR
http://www.bphobbies.com/view.asp?id...83&pid=S003806

I was reading the instructions that came with the Corona receiver
http://www.bphobbies.com/pdf/Corona/RS410_1_Page.pdf

It mentions:
"If not using an ESC with a built-in battery-eliminator
circuit (BEC), plug a 4.8V battery/switch harness into any
unused channel. If you are using all the channels for
servos, use a Y harness to connect the battery and servo
to one channel."

My newbie brain is fuzzed by this. This makes me a bit nervous. I think the ESC has a built-in BEC but I'm not really sure and I don't want to fry any electronics. So do I need a BEC or not? Do I have one and am too green to know it?

AND hey while I'm at it...
Can I use a mixer with this setup to run my servos? If so, is there anything I should look for when purchasing one?

Thanks again to all who share their knowledge so freely!
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Old 03-05-2007, 03:38 PM
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Batteriesincluded, I just threw this together: http://www.wattflyer.com/forums/show...024#post164024

I believe servos, if they will work with your receiver (and there are few incompatibility problems with these, I believe) will work fine with mixing, since it's controlled at the transmitter side of things and one servo does not care what another is doing.

That ESC you referenced has a 1 Amp BEC, so it will crank out about 5 Volts and tolerate up to 1 amp being drawn by the receiver. If you try and draw more, like run a thousand LEDs from it, then the draw would be too high and the BEC would fry.
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Old 03-05-2007, 03:56 PM
  #19  
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Most ESCs, including yours, have a built in BEC circuit. The BEC part of the ESC provides regulated power to run the receiver and servos. The main part of the ESC controls the motor.

It's mainly the very high power ESCs that don't have a BEC. If you have an ESC with no BEC circuit you either need to use a 4.8V battery to drive the receiver and servos or you can use an independent BEC i.e. one which is not built into the ESC.

Steve
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Old 03-07-2007, 09:24 PM
  #20  
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When working with connectors, is there a preference for which end (male or female) go on the ESC vs the battery?
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Old 03-07-2007, 09:33 PM
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Female on the battery. Less likely to short out.
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Old 03-09-2007, 07:05 PM
  #22  
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Tom1968, Thank's for the part about sizing components. You mention "C" rating, I've seen it listed on lipo's, but what about NiMH batterys?
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Old 03-12-2007, 03:02 AM
  #23  
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I'm afraid I've been using LiPos since I got started, so I don't know much about NiMH batteries. I do know that the individual cells that make up a pack come in different sizes, and the bigger cells can supply more current. Some are the size of AA batteries, and some are called "2/3A" which I think are the same diameter as AA but 2/3 as tall. Maybe someone with more knowledge can weigh in here.

BatteriesIncluded, thanks for your feedback. I actually keep that brushless power stuff in a Word document that I started after I killed my first LiPo and realized how much there is to know and how expensive it is not to know it It makes it easy to post the info whenever it seems helpful.
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Old 03-12-2007, 04:37 AM
  #24  
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Question Wiring ????

Hello, being new to the electric side of the hobby I'm wondering, I just received my DX-7 with a AR6100 receiver and no battery how do I charge the transmitter? Also I don't need to use the switch harness included do I ? Thanks!!
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Old 03-12-2007, 05:57 AM
  #25  
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Originally Posted by s-10promod View Post
Hello, being new to the electric side of the hobby I'm wondering, I just received my DX-7 with a AR6100 receiver and no battery how do I charge the transmitter? Also I don't need to use the switch harness included do I ? Thanks!!
Hello S-10

When you say no battery, I assume that you have a battery for the transmitter and a charger for the transmitter battery. The wall wart charger that came with the transmitter is used to charge the transmitter.

The power for the receiver usually comes from the battery that powers the motor in the airplane. The ESC (Electronic Speed Control) has a BEC (Battery Elimination Circuit) that provides power to the receiver and the servos without the use on a second battery. This reduces the weight and complexity of the airplane.

You may or may not use the switch harness, depending on your preference and the type on harness provided with the transmitter. The harness is probably designed to be used in larger glow or gas fueled models, not electric. The majority of electric models do not use a switch harness.
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