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Old Nov 06, 2012, 12:36 AM
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Whiskey Whiskey: thank for sharing, I like the looks of that sequencer. I'll wait and see if BH sents me the right retracts. Have not make up my mind about the stock ESCs yet.
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Old Nov 06, 2012, 03:45 AM
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Australia, VIC, Melbourne
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Back to the Su-repair/upgrade again today.....

After putting back all the nose gear, steering etc, I headed to the battery/RC area and ESC area to do some repositioning and tidying up of things there.

I cut away some of the "V" central foam in the ESC area, so now the ESC's stand 'vertical' instead of forced to lean, by that prior "V" central shape. Because I use a pair of 90A ESC's they were just a bit too big to be on the angle - which makes them "taller" overall. I did 'clamp' them in with the grille plate, but now it is all a proper tidy fit.

Next was the RXes and BECs.
Originally I had one BEC and one RX per "side area" or the battery tray. That all worked fine, it seemed, but I don't really like having an SBEC right near/against an RX !! So I shifted the two BECs into the rear end of the battery tray, and left the two RXes where they had been - one per side.
(You can just make out an RX per pic - one is white, one is black).
The two BECs have their toroids against the very rear of the battery tray, and the 'clean' RX power feeds go out through slits in the rear end of the battery tray.

Then I went over all the TX mixing.... which is a major 'rats nest' of interacting functions/mixes!! I actually need a pre-flght checklist to show me what does what!! I have a laminated A4 page for that!! So I have to read that and go over the functions on the TX prior to flight to re-familarise myself with that plane (as per I have to do on a few others too!). Though it can also be flown in "basic mode" controls too.
Every servo/function has its own channel, and every possbile control surface configuration is availaible - most switchable on/off.
eg Ailevons(?), elevators and elevators in unison, whether elevator instigated, or aileron instigated. Flaperons (Pot), spoilerons (Pot). Tailerons. All the same again with/without TV. "Rudders in" air brakes. A take-off mode mix (a few degrees of up elevator and TV - and some flaperon or spoileron, yet to be determined).
About 20 mixes in total.
Pretty much half a wast of time.... but I may as well have every possible configuration! LOL. And once I decide which are useful, or not, I will trim some off.

.....
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Old Nov 06, 2012, 04:08 AM
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How do you use 2 becs together. I have aleays wanted to do that but read that they would fight each other.
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Old Nov 06, 2012, 04:25 AM
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No.. I have two BECs... one per RX unit. An 8Ch and a 6Ch.... for 14channels used.

There are a few ways you can use two BEC's.....

1) As a fallover to each other.
If they are fed out each via a diode, in theior Pos lead, to the common joint after that, the 'dominant' BEC will be the one providing the current flow. And if one fails, the other will become the 'dominant' one.
BUT you will lose 0.7v of the BEC voltage due to the diodes. That means you will need to select 6V, and will only really be getting 5.3v for the system. Which is still fine in most cases anyway.
That is the cost of getting two to work together.

2) As an increase in current capability.
Servos just need "Volts from somewhere" - it does not have to be the same source as any, or all, other servos come from. But on RXes the Pos and Neg are on a common "rail" and thus go to each servo plug.
You can make up a modded loom so that X amount of the servos still go to the RX, which is powered by one BEC. And the rest of the servos take their power from the second BEC.

To do this, you make a loom of X amount of servo sockets - handy is to cut them off servo extension leads! (you will use the other ends later...). Common up all the Pos leads from those, and all the Neg leads from those. So now you will have ONE Pos lead, ONE Neg lead, and X amount of still individual servo SIGNAL leads.
Those two 'grouped' Pos and Neg are fed from the second BEC (more about this soon...)

You wire up all the signal leads back into plugs, that you had cut off plugs from the prior extension cables, and they go to the RX just as per each servo would have before. From the plugs (it doesn't need to be from all, but I would do from all), which will still also have a Pos and Neg wire out of them, join up all the Negs and join those into the Neg from the second BEC. This is done to COMMON all the Negs across your whole system.
On those plugs cut the Pos wire off flush at the plugs of each of them.
You could 'common' the Negs with just one wire - but if you use the Neg from every plug, that will add stength to the leads - rather than some just having the one signal wire out of it only = thin and weak wire.

Presto... you now have X of your servos and the RX running from one BEC, and all the remaining servos (retracts or whatever) running from the second BEC. Thus sharing the total required current load across the two BECs.
You can decide how to make up the two groups of items, to keep both BECs approx equal loads (tho that is not critical to be perfectly even).
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Old Nov 06, 2012, 05:00 AM
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Pape: Low amp ESC's ~50amp with linear BECs can handle most parallel setups.
Switch BEC can't be put in parallel. The rest is debated by many.

Under the strain of several servos, 11+ servos, retracts, battery under load high EDF load, BECs seem to be vulnerable to nearing a limit.

From further research, the question keeps coming up why do BECs work fine for the Quad prop guys etc. Apparently they're not under the same strain and usually not at the same amp draw levels.

So with EDFs drawing down hard on the battery and ESC, BECs in parallel start getting iffy and have these cases of burning out under the fluctuations.

FW and others run a lot of there ESC BECs in parallel so there is some success and the occasional fail.
But the tell for me is the same FW ESC used on single EDFs have a lot less reports of BEC like failures.
So its just safe practise to by pass the unknowns with a good BEC.
Not sure if the ones Pete added have the power regulator protection since a few talked about it earlier. But then it might be just lighter and more dependable to go with a single RX Lipo batt and CC BEC.
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Old Nov 07, 2012, 01:11 PM
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Since I'm waiting for parts decided to balance the fans. Have both the Du-Bro and Top Flite balancer. Neither one's shaft with go threw the (dome) front part of fan. What to do????
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Old Nov 07, 2012, 01:44 PM
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Used the dubro prop balancer and it worked fine for me.
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Old Nov 07, 2012, 02:10 PM
Wats the worst that can happen
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Quote:
Originally Posted by PeterVRC View Post
1) As a fallover to each other.
If they are fed out each via a diode, in theior Pos lead, to the common joint after that, the 'dominant' BEC will be the one providing the current flow. And if one fails, the other will become the 'dominant' one.
BUT you will lose 0.7v of the BEC voltage due to the diodes. That means you will need to select 6V, and will only really be getting 5.3v for the system. Which is still fine in most cases anyway.
That is the cost of getting two to work together.

You can try using a germanium diode instead to achieve a 0.3V drop instead of a 0.7V drop incurred by silicon diodes.
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Old Nov 07, 2012, 04:55 PM
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I only use Australian diodes!! LOL

I didn't know they still existed! Ahhh, the good old crystal radio......
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Old Nov 07, 2012, 05:04 PM
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Originally Posted by PeterVRC View Post
Ahhh, the good old crystal radio......
Crystals... good?
Not in this life.

Cheers!
Jandro.
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Old Nov 07, 2012, 05:34 PM
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Drilled out the dome( don't know the correct name ) to fit Du-Bro balancer. What are a good replacement servos for the elevators???
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Old Nov 07, 2012, 05:38 PM
Should've, Would've, Could've
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Its called a spinner . Once balanced correctly she'll sound better than a non balanced plane. Some don't take the time to balance and just throw the fans on.
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Old Nov 07, 2012, 09:18 PM
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Quote:
Originally Posted by R. Mike Neely View Post
Drilled out the dome( don't know the correct name ) to fit Du-Bro balancer. What are a good replacement servos for the elevators???

Hitec HS-82 MG. No slop, fast and lots of torque with metal gears. Just a little slice with the knife to squeeze them in the stock plastic mount.
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Old Nov 07, 2012, 10:21 PM
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Spinner, I knew that! (getting more senior momments these days) Received my electric retracts from Banana hobby this evening. Have to use set screws and short shafts from old ones. Need to take apart the old front steering gear to remove shaft and then take apart new one to put it in. Wish me luck!

acesimmer: thanks, back to hobby shop.
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Old Nov 07, 2012, 10:35 PM
Should've, Would've, Could've
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Originally Posted by acesimmer View Post
Hitec HS-82 MG. No slop, fast and lots of torque with metal gears. Just a little slice with the knife to squeeze them in the stock plastic mount.
+1 on that, that's what im using.
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