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Aug 11, 2015, 02:17 PM
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Discussion

suggestions to repower .40 size trainer


I have an old RC Modeler magazine Fledgling.
It is a traditional high wing trainer designed for a .40 ish glow engine.
Oddly, I have never flown it and now I would like to repower with electric and I am looking for any tried and true options out there.
Thanks
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Aug 12, 2015, 08:18 AM
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come on folks
Help an electric nube out please.
Aug 12, 2015, 08:43 AM
Registered User
What's the wingspan and weight?
Are you going to use Lipo batteries? Do you already have existing Lipo's to utilize?

Is it similar to the Eflite Alpha 450?
Look into the Eflite 480 motor. It will use a 3s Lipo and a 30Amp ESC. It will work fine if your aircraft is less than 2.5lbs.
Last edited by philakapd; Aug 12, 2015 at 08:51 AM. Reason: adding example
Aug 12, 2015, 11:09 AM
Registered User
Quote:
Originally Posted by philakapd
What's the wingspan and weight?
Are you going to use Lipo batteries? Do you already have existing Lipo's to utilize?

Is it similar to the Eflite Alpha 450?
Look into the Eflite 480 motor. It will use a 3s Lipo and a 30Amp ESC. It will work fine if your aircraft is less than 2.5lbs.
Also, do you know the wing area? And what is the largest diameter prop that you could comfortably use on it?
Aug 12, 2015, 12:14 PM
Registered User
I converted a Sig Kadet LT 40 to electric. High wing trainer 70" WS.
Here is my setup:
Firepower 40 Speed brushless motor. 800kv 198 grams 5mm shaft
Sky Power 60amp ESC w/switchmode BEC
Rhino 3700mah 4S battery
Motor and ESC are from Headsuprc.com and the battery is from HK
Takes off smoothly and I get 7 min flights at half throttle plus.
Does loops and HUGE rolls! Good setup for a trainer. Lots of fun.
Aug 12, 2015, 06:09 PM
Registered User
plane weight 43 oz empty
no electronics at all right now and has a wing span of 55 inches and an area of 550 sq inch.
looks bigger than the alpha 450
from the prop center line to the ground is about 7 and a half inches.
Thanks
Aug 12, 2015, 08:01 PM
Registered User
scirocco's Avatar
3S pack around 3300-4000 mAh
Turnigy G32-770
12*10 APC-E
Turnigy Plush 60 ESC.
That will give close to 400W with capacity to near 500W with 13x10, or up to about 650W on 4S for future endeavours.
Aug 12, 2015, 08:30 PM
Registered User
Well you could go with a Tacon .32, 4s battery, 60 amp ESC.

Motor
http://www.hobbypartz.com/96m604-big...520-770kv.html

ESC
http://www.hobbypartz.com/07e06-proton-60a.html

Battery
http://www.hobbypartz.com/98p-25c-3300-4s1p.html

Run a 12x6 APC E prop. Motor calc says it should have about 84 ounces of thrust at 600 watts.

As an E noob, please please please take the prop off any time you are going to plug the battery in while it is on the bench. Power and prop will equal lots of pain and suffering. Off to full power in less than a blink of an eye.


Buzz.
Aug 13, 2015, 09:25 AM
Registered User
thanks everybody!!!!
Aug 13, 2015, 04:47 PM
Registered User
I am not disagreeing with any of the setups offered, but I think they may be a bit of overkill for a trainer type plane. Let me offer a more modestly powered setup:

Turnigy G10 810kv
3S battery, 3300mAh or so
40A esc of your choice
APC 13x8 TE prop

I assumed the all up weight of the plane at 4 pounds. This setup would provide roughly:

350 watts of power. That gives 88 watts/pound
55 ounces of thrust. That gives a thrust to weight ratio of 0.85
32 amps at WOT, so a 40 amp ESC should suffice.

It won't have unlimited vertical, but that would give very spirited performance for a trainer type plane. Just another thought.
Aug 13, 2015, 07:17 PM
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scirocco's Avatar
Up to about the 13x8 suggested, the G10-810 is actually a slightly more powerful setup than the G32-770.
The G10-810 would make a better choice if a) the model was looking like being nose heavy and b) there was no prospect of wanting much more power.
If, like a lot of glow conversions a fair bit of weight is needed in the nose to replace a. 40 glow + muffler, then the bigger less stressed motor with capacity for growth makes better sense. This highlights that there are many ways to achieve the desired prop rpm, so other considerations like balance can be tailored without adversely affecting performance.
Aug 13, 2015, 07:36 PM
Registered User
Quote:
Originally Posted by scirocco
Up to about the 13x8 suggested, the G10-810 is actually a slightly more powerful setup than the G32-770.
The G10-810 would make a better choice if a) the model was looking like being nose heavy and b) there was no prospect of wanting much more power.
If, like a lot of glow conversions a fair bit of weight is needed in the nose to replace a. 40 glow + muffler, then the bigger less stressed motor with capacity for growth makes better sense. This highlights that there are many ways to achieve the desired prop rpm, so other considerations like balance can be tailored without adversely affecting performance.
That's a fair point. I have no idea what the balance considerations may be in this particular case. I do see many glow to electric conversions where it seems the power used is pretty over the top. And many of these "glow equivalent" marketed motors don't seem a reasonable replacement for the glow motors they are named after. But then it depends to a great deal on what size prop is used and at what rpm. That is largely why in a case like this a "40 size" plane can be powered quite well by a "G10" motor. The whole "glow equivalent" concept is nice from a marketing standpoint, but in reality it is not that straightforward - unfortunately for newbies.
Aug 13, 2015, 07:46 PM
Registered User
scirocco's Avatar
Quote:
Originally Posted by Yoda466
That's a fair point. I have no idea what the balance considerations may be in this particular case. I do see many glow to electric conversions where it seems the power used is pretty over the top. And many of these "glow equivalent" marketed motors don't seem a reasonable replacement for the glow motors they are named after. But then it depends to a great deal on what size prop is used and at what rpm. That is largely why in a case like this a "40 size" plane can be powered quite well by a "G10" motor. The whole "glow equivalent" concept is nice from a marketing standpoint, but in reality it is not that straightforward - unfortunately for newbies.
Absolutely! The "glow equivalent" labelling and that's all it is without all the other elements such as prop and battery specified can be downright misleading. Imo it's best to ignore any labelling whether glow related or stator dimensions or whatever and focus on 2 key items.
1. Weight - is it big enough to handle the power my model needs. 2. Kv - is it the right Kv to work with my battery and intended prop.
Aug 15, 2015, 08:07 AM
Registered User
I have the Tacon 46, 5s 13x6 prop in a 46 sized aerobatic plane. I pulled a YS .63 out and pout this setup in. It has about the same power, maybe a touch more. I knew the 46 would rip the wings off the trainer.

For a more sedate setup you could always go with the Tacon 25, 3s battery. Thrust is in the high 60 ounces, less than 40 amps at 350 watts.

Buzz.
Aug 19, 2015, 01:29 PM
Registered User
It depends on what you want to do with it. My plane is a little smaller than yours. But I wanted a plane that I can train with, as well as use for our funfly competitions (which requires a more power for the maneuvers).

This setup has worked well for my plane http://headsuphobby.com/Emax-BL3526-...otor-A-274.htm

With this setup I get unlimited verticals at the end of the battery, along with 7-8 minute flight times. And great performance. Just what I wanted.


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