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HomeRC & Power✈️Aircraft🚁HelicopterFlybarless Rotor Head SystemsAlign GPro › Gpro FBL Unit and Power Requirements
07-06-2014 11:32 AM  6 years ago
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coolice

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Gpro FBL Unit and Power Requirements
Hey All.

Flight control system power requirements in a model are often over-looked, more so when an already flying model is converted or has it's setup changed to new hardware and so is taken for granted that it will all work as before.

During a recent conversation with a UK masters pilot, it transpired that one of our fellow team members had experienced and inflight problem while testing his newly fitted Gpro into one of his working 700E's to give it a whirl. He was very impressed with it's performance I may add, however on the 3rd flight experienced what I have determined (going by the explanation of what happened and some new data) to be an inflight reset of the Gpro due to a drop in BEC volts.

Now this guy has been using a Kontronik Heli Jive ESC/BEC combination with another setup all ok, the BEC's output of 5amps continuous in my eyes is too low for a 700 class machine, but it was working and so was used as before.
This change to the Gpro has highlighted a potential problem with low rated BEC's again, in similar fashion to the 3GX as Align increased it's performance with new firmware releases and so current draw/demands increased.

Originally the owner was sceptical that the BEC could be at fault and as we all know, after a crash it's very difficult to determine the true cause, but based on the data he then collected after I'd spoken to him about similar issues the 3GX had, I think he's now resigned to the same conclusion.

Two identical models were compared only differing in their FBL units, in this case Align 700N DFC's, with the 1st using a Vbar and the 2nd was flown by Duncan Osbourn with the Gpro. The latter may have been flown harder perhaps, but the great difference in readings was substantial enough in my eyes to prove the theory that it was a power related problem.

Unfortunately I don't have an Eagletree unit to get some nicer readings, so a Watt Meter was employed to record the maximum amps drawn in flight.

The Mini Vbar returned a 3.88 amps max current draw and the Gpro (in Duncs hands) 14.66 amps max. A startling difference.

My purpose of this post is not to put blame on one unit, but to highlight the need to make sure the power supply setup to your servos fitted to your models is up to the job to avoid potential problems.
.

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters
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07-06-2014 01:10 PM  6 years ago
Eury

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That's a huge difference. I wonder what the Align is doing to have such higher draws.Nick Crego

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07-06-2014 04:54 PM  6 years ago
Busher

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That is a major difference, were the servos similar?, or could it be that the aligns are a bit of an amp hog?.
I was looking to get hold of a 700 this year, in your experience what would you use to power the new 700 dfc dominator with the hv servo setup?
By the way thanks for showing this difference as I was a firm believer in the kontronik becs, but I bet even that couldn't keep up with nearly 15amp.
Good catch
Good luck
Busher
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07-07-2014 01:33 PM  6 years ago
coolice

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Hey Guys.

I'm getting mixed replies to posting this information, so I thank you for your kind words.

Not 100% sure on servos, I think one set were definitely HV BL700 series and the other were the latest 800HV class.
I think it's common knowledge that the Savox and Align (naming the only two I've read about) draw a few more amps than certain others, at least that is what I've read as I've not done any personal testing to say either way.

The Gpro isn't alone in a higher current draw and is at the start of it's career, so will only get better with software revisions. Other FBL units have suffered the same in their early software releases, which have been worked on and refined to make better.
I do not know the in's & out's as to why, but it's just got to be the control loops and programming.
These values are upper limit, so average has got to be around 6 ~ 8 amps if pushed hard.
Unfortunately due to hardware limitations I cannot give more accurate and/or second by second readings, but these give us a good idea even if on the high side due to calibration differences.

I think the bottom line is with a capable power source, in this case a good quality straight 2s LiPo or high power BEC, you eliminate a potential problem spoiling your enjoyment.
Higher voltages reduce loads, but from memory there has been arguments for & against the benefits in the RC system being run at high voltages.

Edit; Removed misleading information to avoid confusion.
Ian Contessa
Team Robbe SchluterUK
Midland Helicopters
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07-07-2014 03:39 PM  6 years ago
Busher

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Thanks for that reply I don't know why you would get mixed replies to this, it a great heads up and from a pilot that knows what he's talking about. People need to do their own testing and show their results before disputing what is right in front of their eyes.
I guess its new tech, and the fact the servos are capable of a stall current of 20kg all that pull needs power behind it. The new system probably has a higher than average base load, as you mentioned will be fixed by further upgrades in the software if it proves to be a problem.
So I guess the favourite power supply will be a straight 2s lipo or similar with an opti power ultra guard in position for backup, and the load from the battery split across a couple of connectors to reduce volt drop.
Good luck
Busher
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07-07-2014 10:31 PM  6 years ago
Angelos

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but Angelos @ Spartan admitted his Vortex suffered the same in it's early software release
No Ian, we are not in the habit of burning customers servos. The post I made in RCHA was not an admission of a shortcoming as you interpreted it. I was for educational purposes so people understand what is happening in an FBL unit and how to avoid wearing our your servos unnecessarily. The Vortex has all required filters from day 1 and we constantly review power consumption of out algorithms when we tweak them.

Ref posts on RCHA: http://goo.gl/URq8YH and http://goo.gl/4v3KAv
Spartan RC R&D
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07-07-2014 11:41 PM  6 years ago
coolice

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Evening Angelos.

Sorry my friend, I'm generaling your own posting of increased current consumption in an earlier software compared to your latest version through development. The ins and outs for the causes are not in the spot light here, just what current figures could be seen and that with revisions to software improvements are made in the demands of the unit.

In no way am I implying servo failures or other in either flybarless unit, so I don't know why this would be mentioned.

While i may be confusing/misinterpreting some information posted, please let's not turn these posts into a competition between brands based on information shared.

Thank you for posting the link to your original posts.

Ian
Ian Contessa
Team Robbe SchluterUK
Midland Helicopters
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07-08-2014 12:40 AM  6 years ago
AWittleWabbit

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What an honest and informative post. I'm paranoid when it comes to BEC. This could explain why some people successfully fly on such low capacity BECs while I wouldn't fly a 450 on a 5 amp BEC.Heli-itis sufferer.
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07-08-2014 12:37 PM  6 years ago
coolice

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Northamptonshire, England

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What an honest and informative post. I'm paranoid when it comes to BEC. This could explain why some people successfully fly on such low capacity BECs while I wouldn't fly a 450 on a 5 amp BEC.
Thanks buddy.
.
Ian Contessa
Team Robbe SchluterUK
Midland Helicopters
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