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Old Dec 05, 2011, 10:07 AM
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fly time's Avatar
Renton, WA, US
Joined Oct 2007
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Quote:
Originally Posted by pookielips1954 View Post
That is exactly why I use a seperate BEC on my multis. I like the Castle Creations 10 amp. Russ Farris
I do use a separate UBEC, but I think the low voltage cutoff (LVC) is a function of the ESC, not the BEC. Even if both ESC's are set to the same cutoff voltage, one will almost certainly activate a milisecond or two before the other, thus reducing the overall load and tricking the other ESC into thinking everything is fine. Looking back on my first accident, it could well have been the same thing occuring. I know some people advocate disabling LVC altogether on twins, and I'm beginning to see the wisdom in that
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Old Dec 05, 2011, 12:13 PM
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Quote:
Originally Posted by fly time View Post
I do use a separate UBEC, but I think the low voltage cutoff (LVC) is a function of the ESC, not the BEC. Even if both ESC's are set to the same cutoff voltage, one will almost certainly activate a milisecond or two before the other, thus reducing the overall load and tricking the other ESC into thinking everything is fine. Looking back on my first accident, it could well have been the same thing occuring. I know some people advocate disabling LVC altogether on twins, and I'm beginning to see the wisdom in that
Disabling is probably a good idea alright. I also bought (but didn't fit yet) a voltage telemetry unit
http://www.hobbyking.com/hobbyking/s...mp_mAh_V2.html
Hopefully this should prevent what happened to me. I'll let you know how it goes.
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Old Dec 05, 2011, 02:19 PM
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Renton, WA, US
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Originally Posted by Luke2000 View Post
Disabling is probably a good idea alright. I also bought (but didn't fit yet) a voltage telemetry unit
http://www.hobbyking.com/hobbyking/s...mp_mAh_V2.html
Hopefully this should prevent what happened to me. I'll let you know how it goes.
Pretty neat gadget

I think I will start by lowering the ESC voltage cutoff to the lowest setting and then be really good about watching my flight times. I think it is currently set for 3 volts per cell. If it goes a little below 3 for a brief period, that is ok. I don't ever fly at full throttle for more than a few seconds, and that is when you see the voltage drop to below 3 volts per cell. All of my newer batteries can handle WOT just fine, but the older ones cannot, especially after a few minutes of flying.
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Old Dec 06, 2011, 01:17 AM
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Guess I forgot to add that part - I disable the red wire on each esc, now the LVC for the motors comes from the UBEC, stopping both motors together. (I think!) I"ll experiment tommorrow with an old tired lipo to test my theory. I'm thinking this should work since the point of having LVC through the BEC is to perserve power for the RX and servos with the motors dead.

Russ Farris
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Old Dec 06, 2011, 05:13 AM
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Darwin Australia
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For everybody’s information.

The Low Voltage Cut Off (LVCO) is a function of the motor control section of the ESC. Its purpose is to cut the motor(s) so that the Main Battery Voltage does not get below that necessary for the receiver to function

The Battery Elimination Circuit (BEC) is a separate circuit that lowers the Main Battery Voltage to a fixed 5-6 Volts so that the Receiver is not supplied with a voltage that is too high. By doing this it eliminates the necessity to carry a separate 5-6 Volt receiver battery.

Ken
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Old Dec 06, 2011, 01:03 PM
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Renton, WA, US
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Originally Posted by kensp View Post
For everybody’s information.

The Low Voltage Cut Off (LVCO) is a function of the motor control section of the ESC. Its purpose is to cut the motor(s) so that the Main Battery Voltage does not get below that necessary for the receiver to function

The Battery Elimination Circuit (BEC) is a separate circuit that lowers the Main Battery Voltage to a fixed 5-6 Volts so that the Receiver is not supplied with a voltage that is too high. By doing this it eliminates the necessity to carry a separate 5-6 Volt receiver battery.

Ken
That is my understanding as well. There is no way to program a BEC to control the ESC's to have them shut down the motors when the voltage gets too low. All the BEC does is step down the voltage from the battery to the Rx while providing sufficient amperage to keep servos and Rx running. The ESC has a circuit that detects incoming voltage and adjusts output to the motors that is independent of the built in BEC.
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Old Dec 06, 2011, 04:52 PM
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Further information.

There is a stand alone devise called the SmartBEC that combines BEC and LVCO functions. This devise is plugged between your ESC and Receiver and has a direct Main Battery connection as well.

This devise can be used to ensure that two ESCs will function in LVCO mode at the same time.

http://www.dimensionengineering.com/SmartBEC.htm

Ken
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Old Dec 06, 2011, 05:05 PM
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Renton, WA, US
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Quote:
Originally Posted by kensp View Post
Further information.

There is a stand alone devise called the SmartBEC that combines BEC and LVCO functions. This devise is plugged between your ESC and Receiver and has a direct Main Battery connection as well.

This devise can be used to ensure that two ESCs will function in LVCO mode at the same time.

http://www.dimensionengineering.com/SmartBEC.htm

Ken
Nice....but with something like this you would not be able to use differential throttle. I have heard that some ESC's are capable of running two motors (Phoenix for example, but it's discontinued), which would give you the same result as using one of these.
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Old Dec 06, 2011, 07:34 PM
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Originally Posted by fly time View Post
Nice....but with something like this you would not be able to use differential throttle. I have heard that some ESC's are capable of running two motors (Phoenix for example, but it's discontinued), which would give you the same result as using one of these.
I have used a Castle Creations Phoenix 10 ESC, an Align 10 Amp ESC and a GWS 15 Amp ESC to run two motors on one brushless ESC. I no Longer use this system as I now use differential throttle steering on my twins.

Ken
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Old Jan 15, 2012, 02:58 PM
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Montreal
Joined Nov 2005
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My latest video with this bird

sorry comment are in French..."made in Québec"
with added comedy speach...

inverted flight + looping with Key chain HD onboard...

you`l find 1 link loss and 1 crash at the end... pay attention LOL

CL 415 au lac Brompton (5 min 43 sec)
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Old Jan 15, 2012, 03:43 PM
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Great video, great flying, but what a great house and place!

À bientôt

Luke
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Old Jan 19, 2012, 11:13 AM
Bob S.
France, Auvergne, Luneau
Joined Aug 2008
81 Posts
Hobbyking Canadair CL-415

Until now, I have been designing paper models on my OLD site www.bobscardmodels.com - NEW one is www.bobscardmodels.net76.net .
My first model (and love!) is the CL-415. I need a new challenge so I want to find an AFFORDABLE kit, which is apparently the Hobbyking kit. Anyone have any more experiences with the kit? What motors are advisable - electric or thermal? And, and, and ......
Bob
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Old Jan 22, 2012, 06:28 AM
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Originally Posted by Bo43 View Post
Until now, I have been designing paper models on my OLD site www.bobscardmodels.com - NEW one is www.bobscardmodels.net76.net .
My first model (and love!) is the CL-415. I need a new challenge so I want to find an AFFORDABLE kit, which is apparently the Hobbyking kit. Anyone have any more experiences with the kit? What motors are advisable - electric or thermal? And, and, and ......
Bob
Hi Bob,

Not sure what a thermal motor is, but I've used/changed a variety of motors with this and found these

http://www.r2hobbies.com/eng/proddet...prod=rcps81531
to be pretty efficient, quiet etc. I've also used cheaper Hobbyking motors and they're probably as good, the difference would be small. Too powerful I found can be a problem at the beginning. I used the cheapie orange servos from HK

http://www.hobbyking.com/hobbyking/s...4kg_0_09s.html

ESCs are HK also
http://www.hobbyking.com/hobbyking/s...idProduct=6460
in the body, just waterproof them and use petroleum jelly (vaseline) around the hatch if using on water, and a 2200mAh LiPo.
This plane flies great. Very scale like and controllable, I'd say even for a beginner with some time on a flight sim (important if you've never flown any rc before). Biggest problems I've had were actually associated with a DX6i transmitter that had a intermittently broken aerial cable at the joint where the thing bends. Otherwise, it's a fantastic plane to fly. It'll go off grass, snow or water with ease. When on water, you'll find that you'll eventually want some form of differential thrust to control direction when taxiing. That's when i ran into trouble!

If you want to save money, go to this site
http://hk.rc-international.info/swarm
It's all HK stuff, from HK but discounted with this buddy system. It doesn't have everything but everything they have is a small bit cheaper.

On those lines, I've been preoccupied with a Turnigy TGY9X transmitter that I bought and converted to ER9X firmware (software?). It can do just about anything but takes a while to figure, it's not like a standard transmitter with a section for flaps, section for inverse etc. but wow, it's good. With help from a dedicated site, I now have differential throttle that automatically reverts to normal after 25% throttle (or whatever I want), flaps that go down slowly and mix in elevator at the same slow rate. It really is good. Can't try any of that or my water drop system due to the weather.

Bob, go for it, you won't be dissapointed. Even if it crashes, it's simple to repair as it's almost always the nose that gets it so there is no alignment problems. Any problems, get back here.

Luke

BTW, that's a nice site you got there. I've been looking through it wondering if any could be made using depron. Can't find a wingspan for them tho???
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Old Jan 22, 2012, 06:39 AM
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BTW,

whilst looking through this site, I found this link

http://rc-buddy.com/post/BuddyPrice-...-for-chrome/63

It adds a background to Google Chrome when on the Hobbyking ite that shows if there's a "buddy code" to get it at a cheaper price. Wish I'd found it sooner.....or maybe I don't
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Old Jan 22, 2012, 10:54 AM
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Montreal
Joined Nov 2005
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Quote:
Originally Posted by Bo43 View Post
What motors are advisable - electric or thermal? And, and, and ......
Bob
foamies dont go well with thermal

ounce you taste the silent & power feeling of electric, you might
throw thermal ancestor to garbadge just kidding...

i use these motor +8x3.8 prop and have plenty of peak power = 300w & save lots of weight on the bird.

there are lots of mods to do also if you want a reliable bird :
--wing spar if you want ot get rid of wing steel support
--rear aileron servo move to inside
--carbon push rods
--differential throttle to get rid of rudder water fin
--heat shrink cut + aluminium tape over the ESC
flat heat sink to keep them cool inside the nacel
(i dont like to run 2" of noisy 3 phase wire and prefer
to pute ESC inside the nacel)
-- fully exposed motor will damage them from my experience...,
either need to create enclosed mount or modify the front hull
to reduce splash effect to motor

Most of crash with this bird happend because of motor or esc failure
and then lead to side twist to ground...
ask me why
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