700 rx fbl servo supply help questions

[greekpilot]

Good morning fellow freaks,
I am about to get a 700 goblin, and I need some help concerning the power supply for the fbl unit, rx and servos.
I will be using the full kbar and high voltage servos (don’t know which yet).

Now I know that the safest way is to use an extra battery for supplying them, but I personally find this a hustle since u have an extra battery to take care of this way (charge-storage etc), plus more weight, and since this is not going to be my daily flyer, maybe 2-3 flights a week with it, I would rather go with an ext bec solution.

My question is, can the full kbar support the amp draw of hv 18-20kg servos at 8,4v?
I assume the full v-bar can, but has anyone tried this setup with the yellow kbar?
And what amp sbec should i be looking for?

Also, since I am new in the 700 size (my biggest bird is a stretched 550 gaui at 2.3kg auw) what servo torque should I be looking at for cyclic and tail? I do fly some 3d and my intention is to progress in that area, so I would like my setup to be sufficient for all maneuvers.
i understand of course that the more torque the better, but from what point on would you consider it an overkill.
Thank you very much for your help guys, and i would prefer opinions coming out of personal experience, not theory.

[Skidpad]

I'm not sure about the kbar, but there's a "setup" (sticky) thread in the Goblin 630/700/770 where dozens of us have posted our individual component selection, headspeeds, etc... You should be able to quickly see what people are running after a few minutes in that thread.

I myself am a receiver pack fan, but have seen plenty of guys running WR or CC bec's on various HV servos on Goblins.

Welcome to the family!

[rcflyerheli]

Like skidpad, I'm not sure about the Kbar, but I do know even full sized Vbars have issues with certain servos. All models of my Vbars would shutdown, have voltage error messages with BK servos.

The new Neo seems immune to the problem, and I switched from a 2s flight pack to a WR Hercules Super BEC Pro for my mini Vbar, which resolved all issues. It's a little pricey, but it does work and if it can save you the cost of a crash, you will have paid for it.

[Excalibur3]

I run a kbar and it works flawlessly on my 500l. But I would never trust it on a 700 class. Too risky brother. Vbars are going cheap these days on the forum. Just buy a used one and call it a day. (Fullsize)

Trex700Pro/Trex700LTop/Trex500L/14sgh T$3D

[greekpilot]

You said you switched to a Hercules super bec, I assume you are running the whole system on 6v? Or 7.4? I was actually thinking of doing sth like this, a yep 20amp bec running everything on 7v. I already have the kbar, so I am trying to find ways to make it work.

[ddhuans]

Originally Posted by greekpilot

Now I know that the safest way is to use an extra battery for supplying them, but I personally find this a hustle since u have an extra battery to take care of this way (charge-storage etc), plus more weight, and since this is not going to be my daily flyer, maybe 2-3 flights a week with it, I would rather go with an ext bec solution.

Trust me, if you can not get a good BEC like WR, so Rx battery is the best, safest way to power your helicopter.
The weight of Rx pack is nothing compare to 5000W power of the motor. I bet you cant feel the different. Just charge it and store it along with your main pack, just take you 10-15 minutes extra charge time. My Pulse 2250 2S Rx pack give me (4) 3 minutes flights full of 3D with RJX servos.

Please be careful with KBar, it's a clone, and may cause unexpected roll or tail blowout. The crash cost of single crash with T-Rex 700 can buy you 2 iKON units. There are many good used FBL units at a good price. Why risk your bird (and your life) like that?
Careful with the YEP BEC too. When it fail, it will pass the main pack voltage to your electronics and fry them. The same with CC BEC Pro.

[K2Freak]

+100! Stay away from the cheap stolen copy fbl controllers!

[greekpilot]

Well friends I understand your concern about the k bar, but I have been using the mini k bar for the last 2years on 3 different helis (450, 500, 550), without a single failure, Brown out or glitch.
I have been generally lucky with my electronics the 20 plus years I have been into rc, in fact the only times I had failures were- believe it or not- with the Futaba 6EX 2.4ghz on original rx's, getting glitches that basically led to totaling 2 warbirds. Never with orange or corona copies. Just luck probably, it just proves that no system is bulletproof.
So myself I have gotten over the brand name assurance, and if sth works well I don't care if it's original or a copy.
Nevertheless your opinions are greatly appreciated and I am thankful for then.

[greekpilot]

Originally Posted by ddhuans

Careful with the YEP BEC too. When it fail, it will pass the main pack voltage to your electronics and fry them. The same with CC BEC Pro.

That is really sth worth considering my friend... I guess the extra pack is a one way street in that sense..

[Skidpad]

Originally Posted by greekpilot

That is really sth worth considering my friend... I guess the extra pack is a one way street in that sense..

There are advantages & disadvantages no matter which solution you choose, it's definitely a personal preference decision. Me personally, I like using a receiver pack, and don't find keeping up with the battery a problem.

[ddhuans]

You have had any issue with them does not mean you will never had any issue with them. I willy use clone (ESC,Rx, FBL unit) on my 450, to save some bucks as I crash it oftenly, it's my beater, but it's not worth to use them on your big and high crash cost like T-Rex 700.
Yes, many of my clone stuffs are very reliable, but I simply dont trust them, and I just want to minimize the risk to crash my T-Rex 700, like I said, crash cost of a single crash can buy you many good and genuine things.
About the BEC, not all the BEC pass through the main pack voltage when they fail, like Kontronik internal BEC or WR BEC, but YEP and CC do that. So if you want to use BEC, try to get the best one.

Originally Posted by greekpilot

Well friends I understand your concern about the k bar, but I have been using the mini k bar for the last 2years on 3 different helis (450, 500, 550), without a single failure, Brown out or glitch.
I have been generally lucky with my electronics the 20 plus years I have been into rc, in fact the only times I had failures were- believe it or not- with the Futaba 6EX 2.4ghz on original rx's, getting glitches that basically led to totaling 2 warbirds. Never with orange or corona copies. Just luck probably, it just proves that no system is bulletproof.
So myself I have gotten over the brand name assurance, and if sth works well I don't care if it's original or a copy.
Nevertheless your opinions are greatly appreciated and I am thankful for then.

[jazsop]

What kind of flying will you be doing. Sport or all out 3d

[jazsop]

I fly KST 725mg and a KST 525mg on the tail of my trex700. They work great and gearsets are cheap.

[greekpilot]

3d is what really interests me, I wanna get as good as I can in it..