Projects New RC Project that has me stressing

[Derek]

oh wow! confused again.

you said to use an Rx pack...it's just a 5cell, not S. I thought that I 5S lipo was a 5 cell. Please correct me if I'm wrong.

Yes, 9 servo's is a lot of draw. I'm doubling the servos on the ailerons because each aileron will be 60" long, so that's 4 servos right there.

I have a BEC, my first experience with an external BEC, on my 60" wingspan motorglider and all works well. If I use a BEC on this BIG plane, why would I need an extra 2s or 3s battery?

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I just read the details on that BEC that you suggested. I see that the BEC has it's own battery hook-up. On my motorglider, I have my external BEC soldered to my main lipo pack. That's why I was confused about that part. There is just so much that I don't understand but I'm really glad that I'm still building this plane because of all the other stuff that I'm learning.

Thanks Tony and I'm sure that I'll be back to harass you some more.

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You said, "If you want to use a BEC, then you can run an extra 2s or 3s battery as big as you want. Just make sure the bec is rated for the amp draw of your servos. 9 servos is a lot of draw so do your math." A lot of the servos that I've looked at recently don't say anything about amps. What am I missing? I'd like to be able to do my own math, but I honestly have no idea what it is that I should be looking for. it's probably something simple that I'm overlooking.

 

[Derek]

Hi Tony! I just wanted to update you on a bit of progress. I did order that Tacon motor, Hobbywing ESC, and 10 servos for my plane. All have arrived and I'm running the servo wired through the wings right now. I still need to order a BEC and a pair of lipos. This monstrosity is coming together nicely...slowly, but nicely. I've gotten some fantastic encouragement from friends, family, and co-workers and I am just stoked to see this plane finished. I'll upload some pictures or a short video when it's a bit further along.

I appreciate you helping out a rookie (me) in his endeavor to make such a plane.

 

[Tony]

It's my pleasure bro. I can't wait to see this thing in the air. Glad to see you didn't scrap it.

 

[Derek]

Hi there, Tony! I forgot to mention that instead of getting the Tacon 110, I did get the Tacon 160 motor. This thing is HUGE!!! ***all smiles***

I'd like to talk with you more about the BEC issue. You were talking about using an Rx pack. How does this work? In a previous post, you said something about using a 2-3S pack, as big as I want. Would the 2-3S lipo take the place of the BEC or would a BEC still be needed?

Also, how does the Rx pack plug into the Rx? I have Deans plugs on all of my lipo's. I'd need to make an adapter, right?

 

[Tony]

A Rx pack is actually totally different from your lipo's. For the 600 nitro, Gaba sent me a LiFe pack that is made for these heli's. It has not only the deans plug on it for charging, and the balance port, but it also has another plug coming off of it to plug straight into the Rx. If you use a Lipo, use a BEC. The Rx can only handle 8v max in most cases and if you hook up a 3s to it, it will smoke it. If you get the life pack, you will just plug it into the Rx. Or you can use any other voltage regulator to bring it down to 6v or 4.8v, whatever your servos will handle.

 

[Derek]

It wasn't until about 3 hours ago, I just learned that the Rx pack that you were referring to weeks ago was actually a totally different thing...as you just mentioned in your post above. I thought I could just use one of the 3S lipo's that I have, already. However, due to what I read today and with your comment echoing what I've read, I finally understand that part. It's a darn good thing that I keep checking back before getting an end result of FIRE FIRE FIRE and my whole beastly project is one giant pool of melted foam, wires, and hopes.

Now...this part has me completely confused and there are few parts to my mass confusion. How do I get a "for sure" (or even relatively close) reading on the amp draw that my intended servos will pull? I'm asking this, for 1, because it would just be nice to learn this fact, for 2, on the Castle Creations website, they illistrate a diagram for using multiple BEC's because the servo's used in their example will pull 2.2amps each on a heli...so just for the cyclic servos, you've got 6.6amps then add on the draw from the tail, gyro, and Rx. So, they illistrate how to wire up two 10amp peak BECs. Here is the link for what I"m talking about if it would help:

Castle Creations | CC BEC Usage Advisory #1

Now..I'm planning on using 10 servo's on my plane. You and I did talk about this before and you said that the 8-15amp BEC that HobbyPartz sells would be sufficiant. I'm not doubting you at all. Your experience vastly outweighs mine. I'm just trying to understand how all this works.

Then...In your post above, you are saying that I can just get a LIFE pack and I can just plug that into my RX. Going this route, I wouldn't even need to bother with getting a BEC? Is this correct?

I do hope for your continued patience with me on this, Tony. It's very frustrating and down right aggrivating that my ONLY source to learn this stuff is through messages on a forum like this, but I'm very glad that you are here to help out. As I've said before, the guys at my local hobby shop are always less than eager to be helpful with my questions unless they can get a "big sale" from me and even then they are very vague.

Ok, I've rambled enough for this post. I look forward to your response. I'm almost starting to think that this "idea" of mine has become a huge waste of time and money.

 

[zenmetsu]

This BEC matter concerns me for one of the planes that I am putting together. I couldn't find a decent BEC that could handle high loads. I will probably go the multiple-BEC route in the end.

 

[Tony]

Bro, don't even think that I'm not more than happy to help you out. Projects like this are why I love this hobby. The people at your LHS are just ass holes that don't really want to earn customers, they just want money. Maybe in the future I will be changing this fact with more than just a forum. If you ever have a question, you don't have to apologize for asking it. I'm happy to help bro.

The LiFe pack can be plugged straight into the Rx. It's 6.6vDC so make sure your servos can handle that voltage. And as with lipo's, as long as the C rating will support the servos, then you will be fine. And you are correct, running a LiFe battery, you won't have to run a BEC.

Figuring out the draw of a servo is the hard part. Some sites will show the draw of the servo, but most do not. If you figure 2 amps of MAX draw per servo, that should get you in the correct area of a C rating or amp rating for a BEC if you wish to use one.

Hope this helps. Again, never hesitate to ask anything on here.

 

[Derek]

Ok, I just rechecked the specs on my servos, it says Input is 5-7volts. So, using a Life pack would be very possible and it sounds like the most simple solution.

Here is the link for the servos at Hobby King, if you'd wanna see:

HXT 10kg Servo (metal gear) 55g / 10kg / .16sec (USA Warehouse)

Ok, now that we have that pretty well figured out, what size Life pack should I be looking for? I do remember the formula you were talking about with the Lipo's. Would the same rules apply here? Since we know that I am using 10 servo's and you are saying 2amps of MAX draw per servo (being 20amps MAX), I'm guessing that I should be getting at least a 2000mAh pack...most likely bigger.

If I had one of those Multi-function Watt Meters, would I be able to hook up a servo to the Rx and esc, then operate the servo and have the Watt Meter tell me an amp reading?

 

[Tony]

Watt meter will only measure the motors, not the servos. And I see you have posted the question on the little area below the ad. Unfortunately I think the only answers you will get are going to be hit and miss. The people that run the site could care less about the questions and never check them unfortunately.

And you need to figure out the c rating to compare the amp draw. 20amps is about right to calculate. If you purchased a 1000mah lipo, you would want a 20c minimum. 10c on a 2000mah and so on. And I would get at least a 2000 mah. After each flight, charge the life pack and see what kind of power you are using per flight. That will give you an idea of how many flights you cna run on a charge after a few flights.

 

[Derek]

ok, I just got home from work and it was a less than pleasant night at work, so let's recap what we've discussed lately.

1. I'm going to be using two 6S lipo's as the power source, in parallel, at least 3000mAh each, probably 25C or maybe a bit more (prices pending, of course)
2. I "definately" don't to get a BEC because now I'm going to be using an Rx pack, instead, that is 2 cell, 6.6V, at least 2000mAh 10C
3. I need to stop apologizing for repeatedly asking for help, lol

Got it!

I remember you talking, briefly, about using an Rx pack in our previous discussions and I think I just disregarded the idea completely because I am "somewhat" familiar with using an external BEC because I have one in my motorglider. For that application, the BEC is probably better than an Rx pack because it's much lighter. However, since I understand what you are saying a little better now, it sounds like then Rx pack is surely the way to go for my big plane. The specs on that Tacon 160 say that the 160 is suitable for a plane that weighs roughly up to 27lbs and I am almost sure that my plane won't even weigh 20lbs so the extra lil bit of weight from the Rx pack won't mean much.

Let me ask you this...on the Castle Creations website, they show the literature from the packaging of their BEC's and there is a paragraph that says:

Servo connectors are not intended to carry more than 5 amps continuously. If your application draws more than 10 amps continuously, please replace these connectors with a connector rated for your amperage.

Is this for real? Do I need to change out the servo connectors? Or is this meant that servo connectors are not intended to carry more than 5amps continuously, each? We kinda figured that there would be 20amps MAX being used here.

 

[Tony]

They are talking about each connector. You are fine on your servo wires, however you will more than likely need to run dual power wires from the Rx battery just to be safe. My LiFe pack has two connectors on it just for this reason. another option is to run dual Rx batteries, but if you have a 20c pack, then I would just solder on another set of wires. YOu are just wanting to split the load between two or more wires.

The issue this brings in is lack of space in the Rx. You will more than likely have to run saddle Rx's to handle all of the servos and plug in's. I can't remember exactly what these are called but they have been discussed on here in depth before. Wish I could remember. I'm sure someone will lol.

 

[breeze400]

If he looks through my f7f build tread they are discussed there. Remember I have 14 servos it that plane. I think they were match boxes weren't they?

 

[Derek]

oh boy....another "something new" to learn, lol. Saddle Rx's??? you are saying to solder on another set of wires...having two power supply wires from the Rx pack to the Rx? If the discharge plug from the Rx pack is the Futaba (based on what I see on Hobby King website), ...........actually, I'm lost again.

I see what "breeze400" has posted below about something called "match boxes." I'll look around for that.

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Hey there breeze400. I'm having trouble finding the f7f build thread that you are talking about. If you could find and send me the link, I'd appreciate it. I'll keep looking. I'm curious to see how you have yours set up with 14 servos. That's quite a few.

 

[breeze400]

Here is the link.

F7F Tigarcat.

 

[Derek]

Thanks breeze. I did find the thread and I did read through it. Your plane looks very impressive! Did you get it up and flying?

I did see where the "matchbox" was briefly discussed, but nothing in detail. I tried to Google it, and couldn't find anything in detail.

I am very much a rookie at rc flying and I probably shouldn't even be building this plane that is stuck in my head but with the encouragement from my wife and counsel from Tony, this plane is kinda starting to take shape. I'm just having troubles understanding what is now being suggested.

 

[breeze400]

I won't be finishing my plane till after the new year. No time. Still have two projects ahead of it. Lol.

You can find the match boxes at horizon hobby. Bacicly you run your say aileron servo wire to the match box. Power the box with a RX battery, and split off your aileron servos from the box. You can also reverse a servo too if needed. Like say my elevator it has two servos running it. If powered thru the RX, the right side would go up, the left side would go down. You reverse a servo through the box and both go up or down.

If you need help understanding this concept, pm me with your phone #. We can chat on the weekend when I am home with the plane and parts in front of me. Then I can concentrate and not strain my brain while driving down the road. Lol.

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I won't be finishing my plane till after the new year. No time. Still have two projects ahead of it. Lol.

You can find the match boxes at horizon hobby. Bacicly you run your say aileron servo wire to the match box. Power the box with a RX battery, and split off your aileron servos from the box. You can also reverse a servo too if needed. Like say my elevator it has two servos running it. If powered thru the RX, the right side would go up, the left side would go down. You reverse a servo through the box and both go up or down.

If you need help understanding this concept, pm me with your phone #. We can chat on the weekend when I am home with the plane and parts in front of me. Then I can concentrate and not strain my brain while driving down the road. Lol.

 

[breeze400]

Here is a link for the jr match box.

http://www.horizonhobby.com/products/matchbox-servo-matching-power-system-JRPA900

 

[Tony]

You are right Sam, it was your thread where I first heard about these and we discussed them. I think we did more talking on the phone than anything lmao.

That is what you will need to run. They are a little expensive, but if you are building a large bird, and you are, they are well worth it.

Bro, don't ever give up on this. This is an EPIC build and "I" want to see this bird in the air! I'm only awake over nights, but if it comes to it, we will have a chat on the phone to help you out.

And when I said you will have to use two leads to handle the power, you will pretty much solder two leads to the board that is in the LiFe pack. This will split the power between the two theoretically doubling your amp rating of the wire. You could also run larger wire, but then you are getting into custom plugs and such and we are not going to go there lmao.

Bro, just take a breath and take it one day at a time. It will come together. Your wife wants to see this in the air and that is more than most of us have on this site. My wife supports me in all that I do, but it's my site so she kinda has to lmao. It's my life. Others on here have a wife that would love it, *ahem* LOVE IT!!! if all of their toys were tossed in the trash and never looked at again. They think we are just over grown kids with toys. And it's so much more than that lol. Give her a kiss for me just for supporting you in this hobby! She is one of the rare women out there and I respect fully any woman that supports this hobby!

Any questions you have, don't be afraid to ask. And if you need it, as Sam stated, you can PM me and I will give you my number. But as stated, I'm only awake at night and really early in the morning.

 

[breeze400]

The match boxes are lots cheaper if you buy the 3 pack instead of one at a time. And you plug in your aux. battery into the box. I'm not sure that you would have to use two leads. Depending apon how many boxes you will need. You can use y battery connectors also.