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Nitro flyer- new to electrics- help !!!

Old 10-29-2011, 05:31 AM
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deanz406
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Default Nitro flyer- new to electrics- help !!!

Hi-- I'm a long time flyer, have been nitro all of that time, started in 1978, and flew up until 1991, and then got busy, and sidetracked with "LIFE" and everything else. I'm retired now, and am "hungry" to get back on the sticks, and enjoy my "GOLDEN YEARS" (If that's what ya call it).
My brother bought me a Champ park flyer last Xmas, and I started flying it around the house this past summer, and he said I needed to start flying again, and "refresh" my flying skills again. Little did I know that I was going to have so much fun again. I was a bit skeptical about this little electric plane, and thought about it as a "kids toy", but when I flew it for the first time, I was hooked. I had so much fun with that little bugger, and flew the h ell out of it. Amazing how rugged it is, and had it into trees, my roof, side of my garage, neighbors barn etc. and only 1 little nick on the nose. I did manage to lose it a few times, but not that i couldn't see it, just that I wasn't used to electric power, and didn't pay attention(or didn'tknow) about the limited flight time. So, I stopped at my local hobby shop, and asked a few questions, bought a few more batteries, and learned a little more. I have a couple acres to fly on, and across the road is a huge open area, probably 8-10 acres, so I have a great place to fly.
What I did discover, was the pleasure of flying , without all the accessories, and huge field box that I used to carry, let alone the fuel, pumps, tools, cleanup stuff etc. Well-- "I'M HOOKED !!! BIG TIME !!!
I now have 6 new electric planes, mostly ARF- PZ Stinson, GP Mr Mulligan, GP T Craft- HZ Cessna 172, HH Pitts, and a Dynam Hawksky.
There is a lot of new "unknown territory" that I am unfamiliar with in the field of electrics, so I'm going to rely on some help in understanding all of it, especially for radios, and the electric power systems, ESC's, and how I understand how to convert a .61 glow engine, to a comparable electric motor. I will post a question on another thread, and continue from there. Any help or suggestions would be greatly appreciated. Thanks, Dean
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Old 10-29-2011, 05:46 AM
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Welcome, Sir! I know nothing about gas conversion but you'll find plenty of help here.
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Old 10-29-2011, 05:49 AM
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Originally Posted by deanz406 View Post
There is a lot of new "unknown territory" that I am unfamiliar with in the field of electrics, so I'm going to rely on some help in understanding all of it, especially for radios, and the electric power systems, ESC's, and how I understand how to convert a .61 glow engine, to a comparable electric motor. Thanks, Dean
Easiest way to do that as my own rule of thumb is I like about 100 watts per pound of all up plane weight. That will give a really good sport flyer with plenty of power.

Mike
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Old 10-29-2011, 08:05 AM
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Hi again, and thank you for the warm welcome. I have done some research on different forums, and have a few questions regarding this glow to electric conversion. Ok, let me start by giving you some parameters of one of the planes I want to convert.

Kit built(Pica I think), W/S-- 65"
Wt, w/o engine, fueltank, rcvr, batt, .61 2 stroke- but w/ air retracts, servos--
9#-- I think it was around 11-12# with the glow,fuel(16oz),rcvr,batt(1600ma)
The prop used was a 14-6 on nitro-flew well scale + a little extra if needed.

OK, here's the info I managed to dig up so far, so maybe someone can explain the different ratings on these motors, and what u think would be appropriate to fly this scale speed, or sport. I don't quite understand the KV ratings, and watt ratings, and how to apply them to a specific weight. Here are the motors I found, from Turnigy, recommended for a .60 size planethis plane could also use a 1.1-1.20 4 stroke)

Turnigy-G60- 300KV--- $52.00
" -G60- 400KV--- 51.79
" -G60- 500KV--- 52.00
" -G110-295KV--- 66.51-- 1.0-1.20 4 Stroke

These were listed for the .60 class airplanes-6.6- 14#-6S & 8S
Scorpion- S4020-8
" - S4020- 14
" - S4025- 12

Hyperion- Z4020-8

Hacker- A50-12L--2200W
" - A50-16L
" - A50-16SV2

I found something with this formula-- Power in watts = 2000 X cu.in(glow)-- Ok, can I assume that .60 X 2000= 1200 Watts ?? Now, how do u apply the KV rating on the motors to arrive at the desired wattage, and how does the battery cell count correspond to the power needed?? I think I saw something about a lower KV rating will make more power, how does that work ??? I am SOOOO LOST !!!

Please bear with me, I know someone out there will have a simple explanation of how this all fits together. Many thanks again-- Dean
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Old 10-29-2011, 01:30 PM
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One of the perks with electrics is you can play around with different size props and pitch to pull more watts and amps or less.

The lower the KV the larger the prop that can be used to pull out those watts and amps. The higher KV you would use a smaller prop. Don't forget to look at what is the largest diameter prop you can put on the plane and leave ground clearance so your not mowing the field with it.

Here is a great thread that I sometimes still go back to, and skim through on motors.
Lot of info in it to digest, but it has helped many of new folks out including me.
Selecting Electric Power Systems
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Old 10-29-2011, 05:08 PM
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Originally Posted by deanz406 View Post
Hi again, and thank you for the warm welcome. I have done some research on different forums, and have a few questions regarding this glow to electric conversion. Ok, let me start by giving you some parameters of one of the planes I want to convert.

Kit built(Pica I think), W/S-- 65"
Wt, w/o engine, fueltank, rcvr, batt, .61 2 stroke- but w/ air retracts, servos--
9#-- I think it was around 11-12# with the glow,fuel(16oz),rcvr,batt(1600ma)
The prop used was a 14-6 on nitro-flew well scale + a little extra if needed.

OK, here's the info I managed to dig up so far, so maybe someone can explain the different ratings on these motors, and what u think would be appropriate to fly this scale speed, or sport. I don't quite understand the KV ratings, and watt ratings, and how to apply them to a specific weight. Here are the motors I found, from Turnigy, recommended for a .60 size planethis plane could also use a 1.1-1.20 4 stroke)

Turnigy-G60- 300KV--- $52.00
" -G60- 400KV--- 51.79
" -G60- 500KV--- 52.00
" -G110-295KV--- 66.51-- 1.0-1.20 4 Stroke

These were listed for the .60 class airplanes-6.6- 14#-6S & 8S
Scorpion- S4020-8
" - S4020- 14
" - S4025- 12

Hyperion- Z4020-8

Hacker- A50-12L--2200W
" - A50-16L
" - A50-16SV2

I found something with this formula-- Power in watts = 2000 X cu.in(glow)-- Ok, can I assume that .60 X 2000= 1200 Watts ?? Now, how do u apply the KV rating on the motors to arrive at the desired wattage, and how does the battery cell count correspond to the power needed?? I think I saw something about a lower KV rating will make more power, how does that work ??? I am SOOOO LOST !!!

Please bear with me, I know someone out there will have a simple explanation of how this all fits together. Many thanks again-- Dean
Here is my method to select a motor for this plane.

Plane weight = 12 pounds

Motor watts based on 100 watts per pound = 1200 watts

Now for efficiency and motor life I want a motor around 1500 watts.

Select your prop, you stated 14x6.

I don't use Turnigy motors but I do sell Scorpion and Hyperion and you can't go wrong with a Scorpion. I also won't talk anyone out of buying a Hacker. Motor choice will be limited by your budget.

If it was me I would use the Scorpion 4020-14 or the 4025-12. We currently have 2 of those in use and have plenty of power. One is in a 6 pound Corsair and the other was in my sons 3D plane that was about 8 pounds. I like to use a lower kv motor because I can use more cells to get the RPM's up using the battery and can typically draw less amps.

The ESC will depend on which battery, prop, and motor you are using. If you run a 6s system the Castle Creations ICE 100 has served me very well on my 4020 powered systems. If you run a 8s system the Castle Creations ICE 120HV is my choice. There are cheaper ESC as well but budget and comfort level come into play here as well. I have seen at least a dozen cheaper ESC's catch on fire over the years and only a few Castles.

Hope that helps, Mike
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Old 10-30-2011, 08:29 AM
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OK-- Gramps-- Thanks a lot for ur reply, and i started reading that article, and am learning a little, but I know I will have to get really engrossed in it, and probably have to read it over several times before it all comes together. I guess the hardest thing I'm trying to get straight, is about the batteries, and the cell count, and how they are rated, as far as voltage and amps, and the count. It's still all greek, so I will keep reading.
The next thing is- what is the relevence of the motor ratings in KV, to the number of cells, their voltage, and watt rating?? I guess the thing I have a hard time understanding, is how this power relates to the torque that a given plane weight needs to fly. Let me try to put it to u this way-- When I fly nitro, I have a 9#, 1/5 scale Cub-- it flies fantastic w/ a .61 glow engine at 1/4 throttle, and has plenty of power to climb vertical at full throttle. This engine is rated at 1.2HP @ 12,500 RPM.
Now comes a little of the confusion-- How can I calculate an electric motors power output that would correspond to an output of 1.2 HP, or some kind of equivalence?? I've always been able to gauge my engine requirements for glow, by the displacement needed, and HP rating of any given motor, for a particular aircraft weight.
Sir Crash-- Thanks for ur input, and suggestions-- Just from some initial reading, am I correct in assuming that the motors u suggest-ie- 4020-12, & 4020-14 refer to the number of cells(12 or 14) that these motors need?? How do they arrive at the KV rating?? Maybe I'm thinking in the wrong direction-- do u measure the voltage of each battery in the cell in order to arrive at the total cell count for a given V x A= Watts ??
You also mentioned u like a lower KV to get more cells, which increase RPM-- Is it that the motors have a sort of unlimited voltage that they can take??

Maybe I should apologize for all the stupid questions, and try to find someone local who can explain it to me, but all of you have been gracious enough to give some guidance, and it is greatly appreciated. I'm going to go back to the article Gramps provided, and keep reading. I will however keep corresponding to this thread, and see if it will finally fall into place. I'm not ready to give up and go back to glow just yet. Many, many thanks again-- Dean
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Old 10-30-2011, 05:18 PM
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Originally Posted by deanz406 View Post
When I fly nitro, I have a 9#, 1/5 scale Cub-- it flies fantastic w/ a .61 glow engine at 1/4 throttle, and has plenty of power to climb vertical at full throttle. This engine is rated at 1.2HP @ 12,500 RPM.
Now comes a little of the confusion-- How can I calculate an electric motors power output that would correspond to an output of 1.2 HP, or some kind of equivalence??

Just from some initial reading, am I correct in assuming that the motors u suggest-ie- 4020-12, & 4020-14 refer to the number of cells(12 or 14) that these motors need?? How do they arrive at the KV rating?? Maybe I'm thinking in the wrong direction-- do u measure the voltage of each battery in the cell in order to arrive at the total cell count for a given V x A= Watts ??

You also mentioned u like a lower KV to get more cells, which increase RPM-- Is it that the motors have a sort of unlimited voltage that they can take??
If you know the horsepower then things are even easier. One horsepower is 750 watts so 1.2*750=900 watts. You also know the RPM's you want to spin a 14x6 prop so you can go to a calculator such as this one:

http://www.ecalc.ch/motorcalc_e.htm?castle

Then you can play with the motor you are looking at to find out how many cells you need and what size battery to get the run time you want.

Using the calc the Scorpion 4020-12, 6 cells, 14x6 APC E prop, and the Castle ICE 100 you will get 10752 rpm's, 1210 watts, at 57 amps.

On Scorpion the -12 or -14 is the number of turns of wire and the 4020 is the stator size. In this case the stator is 40mm in diameter and 20mm long wound with 12 or 14 turns of wire.

The kv is arrive at by running the motor with no load at 10 volts and seeing how fast it is turning. Then they take that number and divide it by 10 to get the rpm's per volt.

Voltage has nothing to do with cell count the way you seem to be thinking about it. Cell count is exactly what it says, if a pack has 3 cells in series it is a 3 cell pack, 6 cells in series is a 6-cell. The nominal voltage of a lipo is 3.7 volts so a three cell pack is 11.1 volts and a 6 cell is 22.2 volts.

So yes, V*A=watts. So 1000 watt using a 6 cell pack is about 45 amps.

Yes there is a limit but I personally have never run into that issue. That is a discussion for a different day. Most motors will run into heat problems from to much power going through them before voltage becomes an issue.

I like more cells with lower kv because it lowers amp draw and I can use a smaller prop. We have a 50cc Extra 260 using a Scorpion 5545-150 motor on 12 cells with a 25x12 prop spinning around 6000 rpms and it draws right at 100 amps. If I can go with 14 cells with a 23x10 prop spins about 7000 rpms at about 77 amps. Problem for me there is the cost of a 14 cell ESC.

Hope this helps, Mike

No such thing as a stupid question, keep asking.
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Old 10-30-2011, 06:56 PM
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Originally Posted by deanz406 View Post
Hi-- I'm a long time flyer, have been nitro all of that time, started in 1978, and flew up until 1991, and then got busy, and sidetracked with "LIFE" and everything else. I'm retired now, and am "hungry" to get back on the sticks, and enjoy my "GOLDEN YEARS" (If that's what ya call it). There is a lot of new "unknown territory" that I am unfamiliar with in the field of electrics, so I'm going to rely on some help in understanding all of it, especially for radios, and the electric power systems, ESC's, and how I understand how to convert a .61 glow engine, to a comparable electric motor. I will post a question on another thread, and continue from there. Any help or suggestions would be greatly appreciated. Thanks, Dean
Hi Dean
Electric powered model airplanes are no longer considered marginal underpowered devices. Those three phase brushless motors, along with their brushless motor drivers (ESC's) and new batteries have really revolutionized this hobby. I've heard comments from other club members that 60 sized glow engine powered models are starting to look like last years technology, as compared to a properly set up electric version. And, a number of my club members own electrics. One member has a $$$$ twin cylinder 150 cc gasser, AND a 50 inch wingspan wildly overpowered electric, along with a pile of other models. Often as not, he will be flying the little electric, and beating the heck out of it.

As for what's involved in converting a '60' glow engine sized model to electric power, take a look:
Thread on 70 size glow engine conversion to electric
http://www.wattflyer.com/forums/showthread.php?t=45222

As for electric motors, I'm an admitted Hacker nut with seven of them from a little A30 series, two A40 series, three A50 series, one A60 series, and am waiting for a Hacker A60-5 motor that's been on order from the LHS for over a month. A lot of other motors are also available, some are very good, some are not. Check around wattflyer to see what works.
Something else, check into those computer programs for electric model airplanes. One good one is www.motocalc.com. Only problem with these programs is the specifications of the motors as provided by the suppliers. Some of those specifications can be way off. Those $$$$ Hacker motors will perform as advertised. A electric Hacker motor equivalent to a four stroke 70 sized glow engine is their A50-16S motor running on six LiPos. (http://www.aero-model.com/Hacker-Bru...50-16S-V2.aspx) In fact, my Showtime 50 setup with the A50-16S motor, 16X12 prop and 7S2P A123 cells way outperforms a fellow clubmembers 70 sized four stroke Showtime 50. But, my flights are 6 1/2 minutes, the glow version can run for 10. (Those A123 cells can be recharged in 15 minutes with a high powered charger)

One good brand of ESC's (Electronic Speed Control) is the Castle Creations ICE series. These ESC's provide on board switching power supply type 5 volt DC power for your receiver and servos. They also include recording flight data that can be downloaded to a computer after one or more flights.

One very nice model well suited for electric conversion is the "Showtime 50" model. I've got one powered by a Hacker A50-16S motor, 16X12 APC-E (Electric) Prop, a Castle Creations 60 Amp ESC, and a 7S2P (7 series, 2 parallel) A123 2300 Mah battery pack. That power system will haul that model straight up out of sight at full power. And, going with LiPo batteries you could perhaps save 1/2 or 3/4 pound of weight.

I've been using those A123 cells now for four flying seasons. They don't seem to ever wear out. Several of my packs have over 250 flights on them, and have the same exact performance as when they were brand new.

Take a look:
http://www.wattflyer.com/forums/showthread.php?t=44686

You get much over a 1 kilowatt powered model setup like the Showtime 50 above, and the price of the equipment really skyrockets. I've got a model with a 3000 watt Hacker A60-16M motor, 12S2P A123 pack and a 19X12 prop. The model weighs in at 19 pounds, and flys quite well. But that thing takes a high powered charger like the Cellpro Powerlab 8, and two 120 Ampere hour deep cycle batteries to power that charger. I'm only getting a years life out of those deep cycle batteries before their ampere hour capacity drops to unusable levels.

These big giant scale electrics with 3000 watt brushless motors almost require a flying site with 120 VAC available.

Last edited by kyleservicetech; 10-30-2011 at 07:23 PM.
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Old 10-31-2011, 06:00 AM
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deanz406
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Hi again Mike-- OK, I'm starting to get a basic understanding of how this is all coming together. I'm still doing a lot of reading, and research, and will study the parameters of these motors, esc's, and battery specifications and requirements. As I mentioned, I have 6 electric ARF's now, and will probably at least stay with the model mfg's recommendations for the motor & esc that they supply. The 1st conversion that I really want to do, is the 65"W/S- 9# Mustang(empty wt), and see if it will fly. I did acquire a Hyperion Z4020-16, so do u think that will work in the Mustang?? I assume I can deviate a little from the 14/6 prop I used with the .61 glow engine.
The next step is figuring out what size battery pack I need(ma rating), like would I need to get something in the range of 5000 MA to get a decent amount of flight time?? Another thing, I still have to figure out which size ESC I would need, and exactly, what is the purpose of a BEC?? How do they work, and is that something that is a necessary part of the electrical system as a whole?? I picked up a few things this week-- a lipo charger, and wattmeter. I'll figure out how to use them properly.

Dennis--Thank you for the thread for the glow to electric conversion-- I printed it out, and will study it intensely. I have looked at the costs of motors, ESC's, battery packs, and it can be very expensive to fly some of the larger models- I mean like several hundred dollars for this stuff. I think a comparable gas setup would be a lot cheaper. I see that the Hacker motors u mention are sorta the Cadillacs of electric motors, and have a very hi quality, and dependability rating. I don't think I'm ready to assemble my own cell packs, so I'll just stick to the ready made ones for now, until I see if I'm going to continue in this direction. As I mentioned, I'm going to do at least one larger model for my 1st endeavor into a conversion. In the meantime, I'm going to build the GP Mr Mulligan, and the Stinson, and play with those for now.
I have a decent start on the Mustang as far as a motor now-- I have some 3000Ma packs, and I'll look at the Castle ESC's, and see what I need, and what they cost. I have upgraded my radios, and have 3 new Spektrum 2.4 TX & RX. I still have a few more radios to get, as I have about 30 planes- mostly 1/5 & 1/4 scale. I like the fact that these newer radio systems have multiple plane capabilities.
Still, there is so much more to learn, so I'll keep trodding down the path to try to have at least 1 successful electric flyer. Maybe u can elaborate a little on the purpose, and relevance of the BEC. My deepest thanks and appreciation for all ur suggestions and help. Dean
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Old 10-31-2011, 07:37 AM
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Originally Posted by deanz406 View Post
Still, there is so much more to learn, so I'll keep trodding down the path to try to have at least 1 successful electric flyer. Maybe u can elaborate a little on the purpose, and relevance of the BEC. My deepest thanks and appreciation for all ur suggestions and help. Dean
Hi Dean
Since you're quite familiar with glow powered models, you're familiar with the common Nih battery pack for the receiver and its servos.

These electric powered models also have a big high performance battery inside that powers the electric motor. This is a reliable power source, but unfortunately the voltage of these batteries is far to high to run your receiver/servo system. Connecting a receiver/servo package directly to a 6 cell LiPo battery will likely blow the receiver and every servo connected to it.

Some of the smaller ESC's (Electronic Speed Controls) have what's called a linear voltage regulator BEC (battery Elimination Circuit) to run the receiver/servos. But using these linear regulators on anything larger than a 2S Lipo battery IMHO might be pushing it. I've seen three crashes in my club this year because of it.

So, the higher powered models need a higher powered BEC that connects to the LiPo battery for its source power, and provides DC power at 5 volts DC to run the receiver/servos. These higher powered BEC's use what's called a switching power supply to run the receiver/servo package. Take a look at what's involved with a uBEC. http://www.wattflyer.com/forums/showthread.php?t=63779

I've used both the Castle Creations 10 Amp uBEC, and the Common Sense uBEC's. Both work well. The Castle Creations uBEC has a programmable output voltage that might be useful if your receiver/servos are rated for a five cell NiH battery pack. These uBEC's run about $25 or so, and save the weight, cost, and hassle of charging the receiver battery after a days flying.

And, as mentioned the CC ICE series of ESC's also include a switching power supply type of uBEC that also works very well.

As you've indicated electrifying a 1/4 scale model gets real $$$$ in a real hurry. Receiver power for these models IMHO should use redundant DC supplies, covered in this thread. http://www.wattflyer.com/forums/showthread.php?t=63794

The electrics can be expensive, but with zero vibration, no servo's being shaken up by that vibration, and no oil soaking through your model after a number of flights, your models will last longer.
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Old 11-01-2011, 02:50 AM
  #12  
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Originally Posted by deanz406 View Post
I did acquire a Hyperion Z4020-16, so do u think that will work in the Mustang?? I assume I can deviate a little from the 14/6 prop I used with the .61 glow engine.
The next step is figuring out what size battery pack I need(ma rating), like would I need to get something in the range of 5000 MA to get a decent amount of flight time?? Another thing, I still have to figure out which size ESC I would need, and exactly, what is the purpose of a BEC?? How do they work, and is that something that is a necessary part of the electrical system as a whole?? I picked up a few things this week-- a lipo charger, and wattmeter. I'll figure out how to use them properly.
Looks like the Hyperion will work for you. I shows about 1183 watts, 56 amps, and 9975 rpm's using a 6 cell battery with the 14x6 prop. Yes, you can change the prop if needed.

The calculator shows about 9 minutes of flight time with a 5000mAh battery.

The ESC selection is actually very easy and I always round up. In this case take 60 amps and add 25% or 15 amps which means you want at least a 75 amp ESC. It is a good idea to leave the 25% to avoid pushing the ESC to hard, some will say it is not necessary but like I said earlier it is all about comfort level for me. Push an ESC to hard and the smoke comes out (sometimes flames as well).

A BEC (battery elimination circuit) is used to eliminate the need for a separate receiver battery. Depending on the speed control you use you might want a separate one or use the one built into the speed control. I have used the built in BEC on the Castle ICE speed controls with up to 5 servos with a 6 cell battery with no issues at all. Once again some will tell you this is a HUGE NO NO on my part. Do you need a BEC no but you do need to power you receiver and servos using some method.

Mike
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Old 11-01-2011, 04:08 AM
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Originally Posted by Sir Crash-A-Lot View Post
A BEC (battery elimination circuit) is used to eliminate the need for a separate receiver battery. Depending on the speed control you use you might want a separate one or use the one built into the speed control. I have used the built in BEC on the Castle ICE speed controls with up to 5 servos with a 6 cell battery with no issues at all. Once again some will tell you this is a HUGE NO NO on my part. Do you need a BEC no but you do need to power you receiver and servos using some method.

Mike
Normally, using an internal BEC on the common ESC's with a 6 cell is a REAL no-no. That calls for one of those uBEC's a switching power supply type of BEC. These things can handle currents on the order of amperes continuously.

That said, the Castle Creations ICE ESC, as well as a few other brands do use a switching power supply BEC rated at something like 5 amperes. I've got five CC 10 Amp external BECs and two Common Sense BEC's. These have gone through 3 or 4 flying seasons, with zero problems or issues.

So, as Mike indicates, using the BEC in the CC ICE series ESC's is not a problem.
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Old 11-01-2011, 06:48 AM
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Dennis & Mike-- once again thank you-- Ok, I'm starting to get the picture about the ESC's and a BEC-- I see that the BEC is the method to supply power to the receiver, without having to use a separate battery for motor, and one for rcvr. You mention that the better ESC's (Castle) have the BEC built in to power the rcvr, but u also mention that a separate BEC can also be used. I guess with the setup I need to use for this plane will require at least a 75A ESC, but a 100 A ESC would be a better option, at least for protecting the planes electrical system. So the BEC, or uBEC gets it's power, through the ESC from the main battery source- is that correct?? Do these deteriorate the capacity of the battery pack, and or render some lower flying times, because they are also drawing power from the pack??
I'm now getting a picture of the system as a whole, but will work on the motor ratings, and requirements, and work on learning more about batteries and cell counts.
Many thanks again, and i have a few other questions to ask about some really decent servos for this plane, and how much power they draw. Dean
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Old 11-01-2011, 07:13 AM
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kyleservicetech
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Originally Posted by deanz406 View Post
Dennis & Mike-- once again thank you-- Ok, I'm starting to get the picture about the ESC's and a BEC-- I see that the BEC is the method to supply power to the receiver, without having to use a separate battery for motor, and one for rcvr. You mention that the better ESC's (Castle) have the BEC built in to power the rcvr, but u also mention that a separate BEC can also be used. I guess with the setup I need to use for this plane will require at least a 75A ESC, but a 100 A ESC would be a better option, at least for protecting the planes electrical system. So the BEC, or uBEC gets it's power, through the ESC from the main battery source- is that correct?? Do these deteriorate the capacity of the battery pack, and or render some lower flying times, because they are also drawing power from the pack??
I'm now getting a picture of the system as a whole, but will work on the motor ratings, and requirements, and work on learning more about batteries and cell counts.
Many thanks again, and i have a few other questions to ask about some really decent servos for this plane, and how much power they draw. Dean
These uBEC's do draw their power from the motor battery. However, under worst condition, the current pulled by my seven Hitec 645MG servos in a 19 pound model came out to be 14 amperes. That was a brief pulse of current that only lasted for a few milliseconds. Even at 14 amperes, the watts (power) pulled out of the motor battery would be Watts=Volts times Amps, or 5 volts times 14 amps. That comes out to 70 watts. The Hacker A60-16M motor is pulling 2500 watts out of the same battery pack, so the uBEC is taking 70/2500 or just under 3% of the battery power.

And, most of the time, that uBEC is pulling far less than 70 watts during a typical flight.

With this 2.4 Ghz radio stuff, you've got to be a little careful of voltage sag caused by overloading the BEC with your receiver and its servos. Even a millisecond long voltage sag can cause the receiver to reboot, resulting in no model control for a fraction of a second. Robust uBEC's can do the job far better than the much cheaper linear voltage regulators used in some of these ESC's. I've checked several of my Castle Creations 10 Amp uBEC's at loads up to 15 amperes and more. At these momentary currents, no voltage sag what so ever was noted with my Tektronix 2236 oscilloscope.

As indicated, I've got a Castle Creations 10 Amp uBEC running those seven Hitec 645MG servos, along with a two cell A123 battery backup system. This model also includes a undervoltage alarm that goes off if the receiver voltage provided by the CC 10 Amp uBEC ever drops below 6.0 Volts DC. After some 50 flights on this setup, it never has.

As for quality ESC controls, you can run the Castle Creations ICE series ESC's (with heat sinks) up to their maximum current rating without concerns. I've done it many times. That said, you CAN NOT EVER run an ESC over its voltage rating. That can result in instant smoke.

As for servos, for a 60 glow engine sized model, methinks any quality name brand servo capable of 6 volts and about 60-80 inch ounces of torque should work well. Hitec, Spektrum/JR, Futaba all make good stuff. When I personally buy new servos, they've been Hitecs.
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