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New to Electric AND RC

Old 12-31-2020, 06:07 AM
  #1  
RKTLaunch
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Default New to Electric AND RC

New is an understatement. I've been designing and scratch building free-flight for a long time. Using those for wing and rib shape research. I came up with some insteresting lessons, and had intended to go RC with what I learned....a long time ago.

I'm jumping straight to scratch designed twin EDFs? I have a lot to learn about how all of the electrics are hooked together. Finding schematics, or even the connectors and what they are called has been difficult so far, but I am making progress.

At the moment I'm trying to make SURE I connect the EDF, battery, ESC and servo tester together correctly...so I don't mess something up. I need to verify both EDFs work. I bought them first, as the whole model is designed around them.... specifically.

I'll try and post a photo tomorrow and see if I'm making any beginner mistakes.

Among a few other things, the basics are twin JP Hobby 6s 70mm EDFs, Castle Talon 90amp w/20a BEC. A servo tester, Admiral 6s 3500, 30C battery. Ev-Peak charger... Futaba 6J transmitter + receiver....some odds and ends....scroll saw...watt meter on the way.

Hello everyone!

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Old 12-31-2020, 03:42 PM
  #2  
firemanbill
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hey there and welcome aboard! Good luck with your project. Looking forward to hearing more about it.
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Old 12-31-2020, 04:52 PM
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quorneng
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A twin 70 mm EDF is certainly a big jump from free flight.
In you list of equipment I assume you mean two Castle Talon 90amp ESC w/20a BEC. You can test each EDF one at a time from one ESC and they should be tested before installation but remember they are powerful and generate a lot of thrust.
When you set up both EDFs to run together you should disconnect the red wire on one ESC. It can cause a problem if both BECs are connected.
Look forward to the pictures.

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Old 12-31-2020, 05:03 PM
  #4  
pmullen503
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Welcome.

A single 3500 mAh battery for two 70mm fans is asking a lot from one battery. Theoretical maximum current for a 30C, 3500 mAh is 105 Amp for the battery and your two fans could draw more than that. I have a (4) 70mm fan model (it draws around 270 Amps static) with (4) 5000 mAh batteries that are rated at 70C. I can fly for 5 minutes and the batteries come down warm but not hot.

Be careful when you run up your fans. You may need bigger, better or more batteries. A watt meter is a good investment.
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Old 12-31-2020, 05:35 PM
  #5  
RKTLaunch
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Originally Posted by quorneng View Post
A twin 70 mm EDF is certainly a big jump from free flight.
In you list of equipment I assume you mean two Castle Talon 90amp ESC w/20a BEC. You can test each EDF one at a time from one ESC and they should be tested before installation but remember they are powerful and generate a lot of thrust.
When you set up both EDFs to run together you should disconnect the red wire on one ESC. It can cause a problem if both BECs are connected.
Look forward to the pictures.
Yes, 1 ESC per motor. One motor at a time. What RED wire?

Originally Posted by pmullen503 View Post
Welcome.

A single 3500 mAh battery for two 70mm fans is asking a lot from one battery. Theoretical maximum current for a 30C, 3500 mAh is 105 Amp for the battery and your two fans could draw more than that. I have a (4) 70mm fan model (it draws around 270 Amps static) with (4) 5000 mAh batteries that are rated at 70C. I can fly for 5 minutes and the batteries come down warm but not hot.

Be careful when you run up your fans. You may need bigger, better or more batteries. A watt meter is a good investment.
I just purchased the one small battery to check the EDFs. I know I'll need a bigger one, or even possibly two, one for each motor. It depends on weight.

In circle #1, this connector fits. I just have to solder it.

Circle #2, This connector fits also, and there are polarity markings on the servo testor, but not on the plug from the ESC. Can't call Castle, they aren't there. Does the in side of the servo tester have to be plugged into something?

Circle #3

The motor connectors do NOT fit into the ESC. They're either 5mm or 5.5mm....again, can't call Castle to find out.

Seem like dumb questions, but I can't make a mistake and ruin something. The connectors are either hard to find, or not in stock. And I don't know what they're called.
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Old 12-31-2020, 06:22 PM
  #6  
pmullen503
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Originally Posted by RKTLaunch View Post
..... What RED wire?.........

In circle #1, this connector fits. I just have to solder it.

Circle #2, This connector fits also, and there are polarity markings on the servo testor, but not on the plug from the ESC. Can't call Castle, they aren't there. Does the in side of the servo tester have to be plugged into something?

Circle #3 The motor connectors do NOT fit into the ESC. They're either 5mm or 5.5mm....again, can't call Castle to find out.

Seem like dumb questions, but I can't make a mistake and ruin something. The connectors are either hard to find, or not in stock. And I don't know what they're called.
The red wire is the center wire on the small 3 wire lead. It provides 5v (typically) for the receiver and servos. If you have two ESCs you typically disconnect one of the red wires.

#1 Those look like XT60 connectors. It's a good idea to plug a matching (not connected to a battery) connector in during soldering so the metal contacts don't move from the heat. A typical 25 watt soldering iron won't be enough you'll need 60 watts or more.

#2 The "in side" supplies 5v to the tester and connected servos. A battery, UBEC, or another ESC connected to a battery can supply the power. You may not need the in side power at all for just an ESC with a BEC circuit as it can provide the 5v, depends on the servo tester.

#3 Those are bullet connectors. You typically have an extension between the motor and ESC so you'll have to make those with appropriate connectors on each end. Get yourself some silicone wire when you buy your connectors. 14 gauge wire will work. 12 gauge is overkill unless the wires are long and it weighs more. Generally, you want the battery close to the ESC with extensions to the motor if possible.
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Old 12-31-2020, 08:19 PM
  #7  
RKTLaunch
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Originally Posted by pmullen503 View Post
The red wire is the center wire on the small 3 wire lead. It provides 5v (typically) for the receiver and servos. If you have two ESCs you typically disconnect one of the red wires.
I understand, but what if each BEC connector is going to a servo or receiver that's completely isolated from the other?
...or scratch that, because all the servo's power comes from the receiver?

Originally Posted by pmullen503 View Post
#1 Those look like XT60 connectors. It's a good idea to plug a matching (not connected to a battery) connector in during soldering so the metal contacts don't move from the heat. A typical 25 watt soldering iron won't be enough you'll need 60 watts or more.es.
Fortunately my soldering gun is 100 watts. That's a good tip...to keep the connector from warping, but these connectors are very shallow. Those wires have a ball of solder on them. Just melt that ball and shove them in, then crimp after cooling, or do i need to put a little solder inside the terminal also? I'm really tempted to purchase pigtails and just cut and solder the wires together. I'm used to terminal connectors that come apart.

The servo tester is GT Power RC, and has no specs or instruction.

I did get 10awg wires for the EDF to battery. I need longer wires. Is that a mistake? Maybe 18 inces long?

Last edited by RKTLaunch; 12-31-2020 at 09:01 PM.
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Old 12-31-2020, 09:23 PM
  #8  
quorneng
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RKTLaunch
This video shows how to use a GT Power RC servo tester.

As you are finding out there is no guarantee that components from different manufacturers have compatible connectors. In general if you look at ther web site the connector type/size are given. About the only thing common (most of the time) are the servo plugs.

Using two completely separate radios and servos is possible but I am not convinced it adds much if anything overall. RC components are so reliable that simply 'doubling up' increase the component count and actually increases the chances of a failure.
Creating true redundancy is done a big expensive planes but it does make things still more complex.
Most systems now have 'fail safe' facilities so any loss of signal sets all the controls to a predetermined level.

Can you wreck anything? Certainly.
For example.
Plug a live BEC connector into a receiver the wrong way round it just wont work but plug it in 'off set' so only two pins connect and there is every chance the receiver will be toast in a micro second!
Make a mistake and connect a LiPo the wrong way round (it shouldn't be possible unless you make a mistake soldering on a new connector) and something will instantly fry and/or burst into flames.
If something gets sucked into a running EDF you have just a fraction of a second to switch it off before something else will be permanently wrecked (the EDF is likely wrecked anyway). A LiPo packs a lot of power in a fault condition.

I am not trying to put you off but power electrics/electronics need care, attention and double checking before physically connecting the battery. .
.
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Old 12-31-2020, 09:33 PM
  #9  
pmullen503
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There is a common 5v bus inside the receiver, so plugging in both ESCs connects their 5v outputs. The problem is that with a switched BEC (built in to your ESCs) the 5v output is not smooth like a battery. There may be a slight ripple and two BECs could theoretically interfere with each other.

10 AWG wire is good for ESC to battery connections. There can be a problem with long battery to ESC wires which can cause the ESC to fail prematurely. The fix would be extra capacitors at the ESC. Castle should be able to advise you if extra caps are needed.

Tin both sides of a connection when you solder and you'll probably have to add additional solder. No crimping required but remember to put some heat shrink tubing to insulate those connections.
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Old 12-31-2020, 10:18 PM
  #10  
RKTLaunch
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Originally Posted by pmullen503 View Post
There is a common 5v bus inside the receiver, so plugging in both ESCs connects their 5v outputs. The problem is that with a switched BEC (built in to your ESCs) the 5v output is not smooth like a battery. There may be a slight ripple and two BECs could theoretically interfere with each other.

10 AWG wire is good for ESC to battery connections. There can be a problem with long battery to ESC wires which can cause the ESC to fail prematurely. The fix would be extra capacitors at the ESC. Castle should be able to advise you if extra caps are needed.

Tin both sides of a connection when you solder and you'll probably have to add additional solder. No crimping required but remember to put some heat shrink tubing to insulate those connections.

I did watch the video. So I need power in, but I'm a little confused about the BEC. That goes to the "OUT" of the servo tester, but I also need to power it up with something from the battery? I was thinking the BEC is a power source. Am I wrong about that? It can power the receiver and servos. Right? My confusion is the servo tester's IN side and OUT side. I'm certainly hoping to power everything with the main battery(s). At least with this EDF test.

The battery(s) will be close to the ESCs, but I actually got the 10awg for the EDF motor wires going to the ESCs. That's what needs to be 18 inches.

I will take time and read both posts carefully before responding to the rest of it.

Haha, I'm also off-grid and on battery power at night, so unless I crank up my generator...I'm stuck reading on my phone.

I appreciate this info a lot.

Last edited by RKTLaunch; 12-31-2020 at 11:48 PM.
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Old 01-01-2021, 12:34 AM
  #11  
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The transmitter, receiver and servos will be Futaba...and they have to be specific to the Futaba 6J. I found that on their website.
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Old 01-01-2021, 09:46 AM
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The servo tester can either be powered from a separate source when testing a servo but when you are testing an ESC it will take its power from the BEC if one is fitted.
The centre and earth pins on both sides of the servo tester are connected together internally so it will work with a power input from either the IN or OUT side.

I would expect Futaba to say you should use one of their servos. You don't!
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Old 01-01-2021, 03:28 PM
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RKTLaunch
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Originally Posted by quorneng View Post
The servo tester can either be powered from a separate source when testing a servo but when you are testing an ESC it will take its power from the BEC if one is fitted.
The centre and earth pins on both sides of the servo tester are connected together internally so it will work with a power input from either the IN or OUT side.
Yes thanks, I was coming to that conclusion. Confirmation helps.

Originally Posted by quorneng View Post
I would expect Futaba to say you should use one of their servos. You don't!
Certainly, but I would tend to use theirs unless they're just overly expensive and I was sure others would work.
Thanks
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Old 01-02-2021, 08:17 PM
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quorneng
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The most important issue with any servo it to pick one suitable for the duty it has to perform and the capability of the power supply.
A more powerful means both more weight and more amp draw.
The last thing you need is for the servos to cause a voltage sag which cuts out the receiver and that usually happens when you are in the air! . .
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Old 01-04-2021, 05:21 AM
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RKTLaunch
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Originally Posted by quorneng View Post
The most important issue with any servo it to pick one suitable for the duty it has to perform and the capability of the power supply.
A more powerful means both more weight and more amp draw.
The last thing you need is for the servos to cause a voltage sag which cuts out the receiver and that usually happens when you are in the air! . .
Only ailerons, elevator and rudder. I don't believe any of which will take much force....torque. The model is basically 30 x 36". Not very large.
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Old 01-04-2021, 05:12 PM
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Originally Posted by RKTLaunch View Post
Only ailerons, elevator and rudder. I don't believe any of which will take much force....torque. The model is basically 30 x 36". Not very large.

That's not that large. You might be able to get by with smaller EDFs and lighter batteries. It depends on the performance you are looking for.
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