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

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.

Maybe use a smaller prop to put less load on the motor? Maybe a certified electric expert will chime in.

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.

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.

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.

Originally Posted by Texastbird

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.

Originally Posted by Bunky F. Knuckle

... 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

• To trust is good
• To calculate is better Will get you to say within 10%, i.e. IF the input is ok.
  e-flight calculators & propdata (compilation)
• To measure is a must
  Without a watt-meter you are in the dark. Until something starts to glow
  A watt-meter will more than pay for itself, several times over, your battery, ESC and motor will love you for it. After calculating, always check current when you have a new/changed setup. Will also help you find optimal setup. And it's a great tool for debugging your power train.
• Keep battery-/watt-/multi-meter wires short
  too long wires batteryside will kill ESC over time: precautions, solutions & workarounds
• close out sale Hyperion Emeter II, with optical and electrical tach, servo tester, local&remote logging - RCG
  originally 200+ $

Originally Posted by Muttdog

... 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)²=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)² × 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 calculators • watt-meters • diy motor tips&tricks • Cumulus MFC •

I think we'll just get another 3s battery.

Originally Posted by Jackdl

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:

• Explanation by Bruce Abbott:
  looking for a 6S small motor. Ideas? - Page 2 - RCG
• Martyn McKinney, Steve Neu and Bruce Abbott also wrote some clever answers in this thread, also addressing input capacitor temperature and why life is easier on a controller at WOT (wide-open-throttle):
  ESC efficiency questions - RCG

Prettig weekend Ron
• Without a watt-meter you are in the dark ... until something starts to glow •
• e-flight calculators • watt-meters • diy motor tips&tricks • Cumulus MFC •

Originally Posted by 3DJP

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%.

Weather is SE Texas is getting decent again. Come on over, MD.

Originally Posted by Texastbird

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.

But will it hover?