How big BEC for FBL?

[Helipsyko]

I have just ordered 3xAlign DS610 for my stretch 650, it has a Rotoworkz HFE frame, originally with mini servos direct to swash, but as I want to put a FBL system on it, probably V-bar, I will mod the frame to fit standard size servos, still direct to swash.
I have read that the DS610 is very amp hungry, but what does it really mean?

So with 3xDS610, V-bar and a S9254 for the tail, svinging 690 blades, how big BEC do I need to be safe?
Mounted today is a Hercules HV BEC, 3.5A continous, not even used! but probably to small.
http://www.helidirect.com/western-ro...age-p-4667.hdx

I do not want a extra lipo pack, I run 2x5000 12s, so plenty of mah.
Do I really need this? http://www.helidirect.com/western-ro...ak-p-11292.hdx
Anyone?

[OnTheSnap]

I plan to eventually go FBL as well. I have about 40 flights on the CC BEC Pro, and I've been very happy with it. And it's very reasonably priced. It has way more capacity then you need for your setup.

[Helipsyko]

Thanks!
Had totally forgotten the new CC BEC, nice!
Was pissed after buying the Herc 3 days before it was released.
So, I will get it anyway
It still would be interesting to know the amp draw of a setup like this, what to think with.

[lavi]

[quote=OnTheSnap;1539113]I plan to eventually go FBL as well. I have about 40 flights on the CC BEC Pro, and I've been very happy with it. And it's very reasonably priced. It has way more capacity then you need for your setup. [/quote]
+1
i had it installed on a logo600 12S and on trex600.6S.
on 12S it goes down somewhat hot, but i guess this is why the heatsink is there. make sure you install it someplace it'll get plenty of airflow...

[teshreve]

I have about a hundred flights on this BEC:
http://www.readyheli.com/Western_Rob...wrl-hbechc.htm

Perhaps I am pushing it and perhaps the WR unit is very conservatively rated... probably both.

I am also using the Align 610 servos, but only 10S.
The 3.5A output of the unit you linked to is unlikely conservatively rated enough

There is this option as well:
http://www.readyheli.com/Western_Rob.../wrl-hbecs.htm
It is heavier and way more expensive than the CC unit, but I had terrible luck with the CCBEC, so unlikely to try again with another BEC from them.
Only after significant positive user feedback would I consider the BEC Pro.

[Mike66]

Originally Posted by Helipsyko

I have just ordered 3xAlign DS610 for my stretch 650, it has a Rotoworkz HFE frame, originally with mini servos direct to swash, but as I want to put a FBL system on it, probably V-bar, I will mod the frame to fit standard size servos, still direct to swash.

I have the HFE and HFX frames, and I am not sure you can (or should) modify the HFE frames to accept the larger servos. The HFX frames come with more hardware to support the output shaft of the servo.

[Helipsyko]

Thanks for all replyes.
I am replacing the top "servo frame" with 2.5mm carbon sheat, i make it a bit longer so it includes the 2 screws for the boomblock. I have KDE metal bottomplate, 8mm plexi battery tray, metalbearingblocks and several extra suport rods. I do not se the problem at all.
Why?

[Mike66]

It sounds like you have resources available to you to make the parts fit, which I do not. The larger servos are a tight fit in the HFX frame, which is about 4mm taller than the HFE frame to accommodate the extra space required. Good luck!

[Helipsyko]

Tight, YES. Have not done it yet, so it will be a challenge, though you meant that it was not strong enough, as you wrote "should".
The opening in the main frame is 5 cm high, the space from the holes in a standard size servo is also 5 cm, the shaft will be in the middle giving only, lets say 3.8 cm, or 1.9cm on each side, free space between the frames, so it is a challenge allright.
Needs spacing and massage.

[Flexis]

After hearing some horror stories about CC bec's I'm steering way clear of them. For my Logo 500 I went with the very tried and tested workhorse of all bec's. As already mentioned before the WR Hercules 5A. I hear someone tested it to 20A before if eventually failed. So i'm guessing this bec is rated very conservatively.
It would probably be just fine on your setup.

[OnTheSnap]

Yes, the old 10A CC BEC had some quality issues, which were addressed in later revisions (so I hear). It's funny that we all use their ESC's, but then freak out about a simple DC/DC.

So far I've found the CC BEC Pro to be of extremely high quality, using all the ESC knowledge they've acquired since the 10A BEC. It's an outstanding product that reasonably priced. I give it a 10/10 after many hard flights on it with my 600E.

[Helipsyko]

I have the CC Bec 10a on my 450, and have ponded it to the ground close to 50 times with no problem at all. Using 3s, 4s and 5s setups on it.
Would not worry at all about CC quality.
Will order a CC Pro asap.

[teshreve]

I would. I have burnt 3 and a buddy 2.
The fact is that the WR units are way more tested and have been around way longer. I have not heard of a single WR failure and have heard of (and experienced) many CCBEC failures.
If, given this info, you are still OK with trusting your megadollar heli to an unproven product with a bad track record, sweet!
I still run one, actually, but on 3S. And not in a heli.
It seems to be 6S that kills them.

[OnTheSnap]

It's really not fair to say the BEC Pro has a bad history. It's the CC BEC 10A that had the issues. There is nothing in common between the 2 designs as far as I can tell other then 2 years of learning and product releases from CC.

I trust my CC85HV and my CC35. So why not the CC BEC Pro?

With out a doubt there is no history on this product, and there is risk of failure(just like every piece of electronics). I can only convey my own experience as an early adopter. I understand the personal prejudice you have against CC BEC's due to your bad experience with them. They're also using a very modern buck controller and high quality FETs. I couldn't ask for much more then this.

BTW, a higher input voltage is way more stressful on a BEC since it has to run at a lower duty cycle. So I'm not suprised 6s caused a problem. The BEC Pro looks way over engineered and CC isn't planing to repeat it's old mistakes as far as I can tell.

[Flexis]

Well, if the ESC fails, then the ESC fails. With a little luck you can auto, buy a new ESC, end of story. If your BEC fails however, your doomed, and if you are really unlucky your electronic are toast too. And that's expensive!
I run CC ESC's on both my heli's but I only use a proven design for the BEC. If in a year no one has had failures on the CC BEC PRO, I consider it proven, untill then I'll stick to what I got.

[Helipsyko]

Originally Posted by Mike66

I have the HFE and HFX frames, and I am not sure you can (or should) modify the HFE frames to accept the larger servos. The HFX frames come with more hardware to support the output shaft of the servo.

After some cardboard cutting, testing and adjusting I can say that the mod will be no problems.
The hole in the main frame is large enough to fit both the full size servos, the one for elevator have to be mounted standing like the 9650, and the ailron/pitch will need a 5mm spacer to clear the main shaft with 1mm.
Then put the Rotoworkz servo arms on the inside of the servo wheel of the ailron/pitch and put on a medium long link ball.

[Mike66]

Originally Posted by Helipsyko

After some cardboard cutting, testing and adjusting I can say that the mod will be no problems.
The hole in the main frame is large enough to fit both the full size servos, the one for elevator have to be mounted standing like the 9650, and the ailron/pitch will need a 5mm spacer to clear the main shaft with 1mm.
Then put the Rotoworkz servo arms on the inside of the servo wheel of the ailron/pitch and put on a medium long link ball.

Good job! You should send Charley a picture of your design when you are finished.

[Helipsyko]

Originally Posted by Mike66

Good job! You should send Charley a picture of your design when you are finished.

Thanks! Good idea.
Have a question regarding the servo "saver" parts on the HFX frame, is it bolt on, on the servo, as in can be used on "any" servo? Or? I mean the S-shaped arms to the left on the picture.
Do you have any close up pictures of them on the heli??

[Helipsyko]

"Have a question regarding the servo "saver" parts on the HFX frame, is it bolt on, on the servo, as in can be used on "any" servo? Or? I mean the S-shaped arms to the left on the picture.
Do you have any close up pictures of them on the heli??"

Never mind, found them on the Rotoworkz webpage.

[Mike66]

I haven't assembled my HFX frame yet, but I fly the HFE frame. I don't know if you have seen them, but here are two Finless Bob videos on the RotorWorkz frame assembly:

HFX

HFE