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Old 11-18-2019, 06:15 AM
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A few questions about large electrics

Hey all, Haven't been around here for a few years but am back and am trying to apply some electric Heli tech into a large (50cc size) airplane. I am not new to giant scale, I've been a gasser for quite some time but I'm interested in trying my hand at large electric.
One of the questions I have is on Rx/flight pack batts.
I see several talking about using certain buffers and some redundant systems with external Bec's but I have several Scorpion Tribunus esc's (200 amp) with bec's and plan to run my Xpert heli cyclic servos in the 2 airplanes I have with gas now, converting to Dual fly GA 6000.8S in the first. I run Jeti equipment in my helis and Spektrum in my smaller (55-74") electric airplanes.
Jeti has the DSM ESC switch that ties the internal BEC to an extra Rx pack batt and am looking into trying that. I'm sure everyone has advice one way or the other but I've become quite accustomed to the reliability of the Tribunus esc and the never ending power supply amp-wise, that this esc has been pushed to with no faults.
I've never been around the Giant scale electrics so I'm asking for some input on setup in general.
I might also add as a MSHeli team pilot, we had access to certain components at team pricing, the esc's being one, but also Batts, so I have 24 sets of gens ace 5000mah 45c batts with 11 sets still new in box, so I'm planning 12s, 24X9 Falcon on this (estimated) 15.75lb airplane-Aeroworks Yak, and possibly the same system on a modified EG aircraft MX2.
More than willing to listen to suggestions on this venture and thank you for any help and advise.
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Old 11-18-2019, 07:03 AM
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Sounds like you're on the right track.
The Scorpion ESCs are solid and should work well with the GA6000. They also have a pretty capable BEC. Should be fine to use it, but I'd add a Scorpion Backup Guard as a redundancy.
Do you have the single shaft or 4-bolt hub? I prefer electric props on my three GA6000 motors.
The best place for giant scale electric power system feedback is the power thread on rcgroups.
https://www.rcgroups.com/forums/show...light-Fanatics!
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Old 11-18-2019, 05:12 PM
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There is some good reading in that thread-very long, but I jumped ahead quite a ways to more current info with newer tech.
I find it amusing the concerns of hot motors and hot Batts in some of those threads..:-))
Technology has changed a lot from original writings but very good information, appreciate you pointing me in that direction.


Instead of the scorp backup or Optiguard I was considering this:


http://www.espritmodel.com/jeti-elec...ual-power.aspx


Using a R3 Rx switch, this can be switched on/off from Tx without the magnetic plug when using Jeti systems.
The processor allows highest voltage to be used so if running a 2s lipo, set voltage to 8.2 and in hard maneuvers a voltage drop of .2v, the processor allows lipo input until load requirement drops then switches back to BEC. If BEC fails, it's all on lipo without fail and any size lipo you choose can be used.
Very similar to PCB on optipower optiguard sensing .5v drop and switching over.
Very curious if anyone has tried this setup.
Thank you for the help.


Edit: I forgot to add my first motor is the single shaft. Seems like a lot of demand from a single bolt/nut on a 22-25" prop but found several recommendations for single shaft.
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Old 11-18-2019, 05:54 PM
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Ken,
That Jeti unit is rated a 10a max continuous / 20a peaks. I'd aim a little higher.
Booma makes a unit good for 35a continous
http://www.boomarc.com/en/multi-switch
and there is also the Western Robotics batt buffer device good for 24a continuous (not switched though).
http://www.western-robotics.com/BBFR

There is no problem with the single shaft - I'm pushing up to 6800-watts through mine with a 25x12 prop on a 25-26# plane (120" Bushmaster)

For your lighter setup, a 23x10 to 24x10 at 5000-5500 watts will be fine (and more efficient than a gas prop).

Have fun and good luck!
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Old 11-18-2019, 06:29 PM
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Quote:
Originally Posted by KSKen View Post
Hey all, Haven't been around here for a few years but am back and am trying to apply some electric Heli tech into a large (50cc size) airplane. I am not new to giant scale, I've been a gasser for quite some time but I'm interested in trying my hand at large electric.
One of the questions I have is on Rx/flight pack batts.
I see several talking about using certain buffers and some redundant systems with external Bec's but I have several Scorpion Tribunus esc's (200 amp) with bec's and plan to run my Xpert heli cyclic servos in the 2 airplanes I have with gas now, converting to Dual fly GA 6000.8S in the first. I run Jeti equipment in my helis and Spektrum in my smaller (55-74") electric airplanes.
Jeti has the DSM ESC switch that ties the internal BEC to an extra Rx pack batt and am looking into trying that. I'm sure everyone has advice one way or the other but I've become quite accustomed to the reliability of the Tribunus esc and the never ending power supply amp-wise, that this esc has been pushed to with no faults.
I've never been around the Giant scale electrics so I'm asking for some input on setup in general.
I might also add as a MSHeli team pilot, we had access to certain components at team pricing, the esc's being one, but also Batts, so I have 24 sets of gens ace 5000mah 45c batts with 11 sets still new in box, so I'm planning 12s, 24X9 Falcon on this (estimated) 15.75lb airplane-Aeroworks Yak, and possibly the same system on a modified EG aircraft MX2.
More than willing to listen to suggestions on this venture and thank you for any help and advise.
If you're on Face Bk check out the "HV Aviation - electric powered aircraft group". Lots of good people knowledge and experience in there so far. (sorry can't post a link because FG is strange)
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Old 11-18-2019, 08:37 PM
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Hey, I appreciate the help here guys!
I have a somewhat unique situation here in that I'm at 3800ft elevation and I have 2 choices when selecting a powerplant for my aircraft. For 50cc size, I install a 70cc, for 35cc, I use a 50, etc.. What I've discovered on electrics is I can go with a bigger prop than suggested to get performance back without adding tremendous weight-OR-additional amps. This has become very attractive to me (the electric route) so I can fly the aircraft without fighting the extra weight of a bigger combustion engine. So it's so much better for me to just change props back to recommended if I fly at lower elevations. I'm theorizing the large scale will be similar to the smaller electrics I currently fly.
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Old 11-18-2019, 09:28 PM
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Quote:
Originally Posted by terryscustom View Post
If you're on Face Bk check out the "HV Aviation - electric powered aircraft group". Lots of good people knowledge and experience in there so far. (sorry can't post a link because FG is strange)
I see KD is admin for that site. He sees my request I may never get there :-)) such a small world!
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Old 11-19-2019, 07:03 PM
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I'm a big fan of the K.I.S.S. method. Your system should work perfectly well but I'll share what I do and why anyway.
I don't like to use built-in BECs as in most cases if an ESC fails it will not keep the internal BEC power supply and you'll lose control of the plane. Tribunus is a high quality ESC and probably has many failure protections (overcurrent, overtemp, etc) so maybe not a real concern for you.
For a 50cc size electric I really don't see the need to have extra rx pack and simply prefer to power the rx with an external SBEC (supplied by the main packs) and use a backup battery (I use the Scorpion Backup Guard) as redundancy in case of SBEC failure.
Since you already have solid built in BEC on the Tribunus, I'd only add a backup like the scorpion. Simple and light setup.
Ronaldo
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Old 11-20-2019, 01:55 AM
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Suds, Thanks for the input and wow, that Bushmaster at 6800w w/25x12 must have some serious authority!


Terry, appreciate the direction on the FB group, quite a few guys there that are friends-I didn't know that group existed there, I've been out of the loop too long, really appreciate the help there. I've picked up a lot here just reading-I won't just leave without updates, a lot of good peeps here.


Ronaldopn, kinda reminding me of the heli world there :-)) I love the idea, just not sure with the servos I'm using that I want to stretch my luck that far-not sure of the limits of the Scorp with 5HT servos, I know it's bulletproof with 3 @ 450oz w a 120oz on tail going crazy on a FBL system, just don't have that warm fuzzy running 5 at 450oz. I've abused that 200 Scorp with 3 min flights on an 800mm size heli on 12s pulling well over 200 amps without fail so I know the esc is tuff, just not sure where that line is on the bec. I need to research more, but thank you for the photos and ideas!
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Old 11-20-2019, 07:45 AM
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The Scorpion BG is just meant to act in the unlikely event of failure of your built-in BEC. It has enough capacity to allow you to finish an electric flight and land safely. You'll probably feel a difference in response speed at 5V if your servos are HV which will also be a helpful warning that something is wrong but 10A are definitely sufficient to fly and land safely a 50cc.
I believe Tribunus has data logging and telemetry so you could make a test flight to see exactly how many amps you'll be seeing in a typical flight.
Regarding external BEC, Castle has one at 20A and Hobbywing has a 25A unit if you're scared of the cheap HK stuff I use (YEP 20A).
Ronaldo
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Old 11-20-2019, 08:33 AM
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A few days ago I had a question on the Power Systems thread on RCG about the YEP 20A SBEC I use which was cool because it made me look at the log data which is always interesting. The discussion is here in case you want to take a look.

NOTE: I'm not sponsored or promoting HK stuff by any means just showing that you can go really simple on the setup. You're probably safer with a CC or HW SBEC.

The previous setup I showed with the HW 200A is for a new project I'll be running on 14S (that is why I opted for the XT90s). For 12S I recommend AS150 connectors or similar.

Below are 2 videos of my Fly Model Extra 330SC 50cc with the following setup:
Turnigy Rotomax 50cc rewound to 198kV
23x12 Aerostar electric wood propeller
12S 5000mAh 70C (CHL Graphene series)
CC Edge 160A
YEP 20A SBEC
Scorpion Backup Guard
JX PDI-HV7246MG 46KG Digital Coreless Standard Servo all around.
This is the 3rd flight of the plane, brand new:
Fly Model Extra 330SC 50cc Electric Powered - 3rd flight (5 min 45 sec)

This was made after a major repair, plane ended up too heavy and I sold it to a friend (sport flyer).
Fly Model Extra 330SC 50cc electric (22Jun19) (4 min 41 sec)
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