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Old 11-26-2019, 08:09 AM
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Going 4S on apprentice

My dad who lives in Tx. got an apprentice last year along with a couple batteries. I am purchasing a Timber X that I will be taking to Texas to do some flying with him. My question involves using the 4S packs for my Timber X in his 3S apprentice. What do I need to get to make that work? We don't need more power or anything like that. I only want to use one battery between the 2 planes. I thought we only needed an ESC but one of the electric guys at the field said the motor had to be changed as well. I don't fly electric so this is all new to me. Any tips would be appreciated
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Old 11-26-2019, 08:23 AM
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I used a 4S in my Apprentice. I think I saw somewhere that the speed control can handle it but not sure the motor will so I limited the throttle endpoint on the transmitter to 75%. I flew it several times this way with no problem but I don’t know what the long term effect would be.
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Old 11-26-2019, 10:18 AM
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Maybe use a smaller prop to put less load on the motor? Maybe a certified electric expert will chime in.
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Old 11-26-2019, 10:39 AM
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Smaller prop, or limit the throttle, depending on Tx used.

If the prop is a12x6 on the Apprentice, drop prop size down to an 11x5. You will be lowering the Amperage across the board. Should be able to use full throttle, with the 4S packs.

Best to get a Watt meter to check your amperage on 3S and 4S.
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Old 11-26-2019, 10:51 AM
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Good news, so basically just go easy on her and everything should be ok. I am still using buddy box to teach my dad so we will basically set the throttle to cruise power and leave it alone.Thanks everyone.
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Old 11-26-2019, 01:20 PM
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Muttdog, from reading your posts over the years, I don't think you can go easy and leave it alone, ha ha ha. (All in fun) Apprentice is a great trainer. Hope y'all have fun.
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Old 11-26-2019, 01:39 PM
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Quote:
Originally Posted by Texastbird View Post
Muttdog, from reading your posts over the years, I don't think you can go easy and leave it alone, ha ha ha. (All in fun) Apprentice is a great trainer. Hope y'all have fun.

That's why I bought the timber X LOL.
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Old 11-28-2019, 08:02 AM
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Quote:
Originally Posted by Bunky F. Knuckle View Post
... Best to get a Watt meter to check your amperage on 3S and 4S.
Without a watt-meter you are in the dark. Until something starts to glow

Quote:
Originally Posted by Muttdog View Post
... My question involves using the 4S packs for my Timber X in his 3S apprentice. ...
Target: keep pitch speed and power drawn the same.
  • Pitch speed is proportional to rpm, and therefore propotional to voltage, and proportional to pitch.
    It would increase by factor 4/3. To keep pitch speed the same, pitch should change by factor 3/4.
  • Current drawn is proportional to voltage squared.
    By going from 3s to 4s, current wants to increase by factor (4/3)=1.7.
    Extra current with one or two cells added, simple table
    A.k.a. "Why did my motor and/or controller and/or battery go up in smoke ??? .
  • Current drawn is also proportional to pitch
    The changes in voltage and pitch together result in a total change in current by factor (4/3) 3/4 = 4/3.
  • Power = voltage current
  • I have to go, not finished yet. I'll be back!
  • ... ...
  • Safety: can the prop handle the higher rpm?


Vriendelijke groeten Ron
• Without a watt-meter you are in the dark ... until something starts to glow •
e-flight calculatorswatt-metersdiy motor tips&tricksCumulus MFC
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Old 11-28-2019, 10:44 AM View Post
3DJP
A moderator felt this post violated the following rule: Trolling (Provocation). It is temporarily hidden while 3DJP edits it. Show it to me anyway.
Old 11-29-2019, 05:57 PM
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I think we'll just get another 3s battery.
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Old 12-01-2019, 09:28 AM
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Quote:
Originally Posted by Jackdl View Post
I used a 4S in my Apprentice. I think I saw somewhere that the speed control can handle it but not sure the motor will so I limited the throttle endpoint on the transmitter to 75%. ...
Although not the case in your system ...
If current at wide open throttle is too high for the controller then reducing throttle to get current below ESC max.current is not a good idea. In fact, it is even harder on ESC than to keep overamping at full throttle. Better to prop down a bit to reduce current.
See:
Prettig weekend Ron
• Without a watt-meter you are in the dark ... until something starts to glow •
e-flight calculatorswatt-metersdiy motor tips&tricksCumulus MFC
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Old 12-01-2019, 09:16 PM
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What a character!!
I said the same thing he did, without all the tech talk.

I have seen guys use 6S on a 5S system. Know what they did?? Lowered the high throttle point from 100% to 75%.
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Old 12-02-2019, 11:51 AM
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Weather is SE Texas is getting decent again. Come on over, MD.
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Old 12-02-2019, 04:31 PM
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Weather is SE Texas is getting decent again. Come on over, MD.
Can't wait. I'm headed to Round Rock in the Austin Area for Christmas to see my parents. Wish I could fly with you guys but TX is just so big that everything is just too far away. I was searching the classifieds in Tx for an electric plane but everything was a 3-6 hour round trip. I settled on bringing the Timber as it can be put back in it's OE box and shipped home.
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Old 12-02-2019, 05:06 PM
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Gettin better 1 [email protected] a time!
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But will it hover?
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