By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by CML

Possibly going all electric, which motors should I use?

All Topics | Latest Posts

Search for:  in Thread Title in  
Foxfan25/08/2019 22:24:05
avatar
800 forum posts
6 photos

Trevor, I'm a great fan of foam. I've made a Skystreak 32 in Depron for when I can fly well, simply because I love the shape and had a KK Skystreak 26 as a kid on the top of my wardrobe. Never forgot it.

But there are few plans available for a quick Depron build. I have a Vulcan plan with a pusher, but it needs making more scale-like for my tastes. A square section Vulcan tends to grate, even if a pusher is invisible when it's flying.

But I like your comments about times of flights.

BTW, except where it occasionally states it in the ad., how does one know what wattage a motor is?

Cheers,

Martin

Kim Taylor25/08/2019 23:58:48
274 forum posts
53 photos
Posted by Foxfan on 25/08/2019 22:24:05:

BTW, except where it occasionally states it in the ad., how does one know what wattage a motor is?

 

Cheers,

Martin

Hi Martin.

I too came in to electrics 'cold' and struggled with the numbers (or lack of) in the adverts, so my advice is to treat ALL the figures quoted as suspect until you test them yourself. However to give yourself a chance of getting it right first time, this is my understanding of how it all splices together:

You can get a notional maximum wattage by multiplying the maximum rated amps of the motor by the voltage being applied by the Lipo. So for instance a 30A motor on a 3s Lipo would be a notional 330w, but it all depends on the prop load which you put on it.

That's why having a means of measuring the absorbed current when the prop is turning at WOT is important - so that you know (a) what the current (and wattage) is and (b) you're not overloading the motor or esc.

Kim

eta

With regard to the original question regarding the Wot4, I would challenge anyone to get a full size ARTF Wot4 electric below 5lb in weight (with a sensible powertrain, that is). I've checked at length on various threads and most come out at 5.5lb or more with a 4 or 5s setup. My own, with a 3000mAh 6s was a smidge under 6lb.

A build it yourself may be lighter, but I've got no experience (yet) of the kit version.

Kim

Edited By Kim Taylor on 26/08/2019 00:06:27

Foxfan26/08/2019 14:38:42
avatar
800 forum posts
6 photos

Kim, I know the old Watts equals Amps time volts formula, but apart from a statement of recommended ESC amperage, there is rarely a mention of the ACTUAL amperage of a motor, so it's still difficult to assess a likely wattage, which is as you said to some extent dependent upon model size, prop size, etc.

I didn't ask about a Wot4, btw. I hate them! Ugly pigs.

Martin

Mike Blandford26/08/2019 15:08:03
avatar
522 forum posts
22 photos

What radio gear do you use? I ask as I use FrSky and have recently started to use the FrSky Neuron ESC. This provides all the telemetry data for the motor, such as voltage, current and RPM, as well as the possibility of setting a maximum current to protect everything.

Mike

Foxfan26/08/2019 15:12:16
avatar
800 forum posts
6 photos

Mike,

I have very basic Spektrum DX5e Tx., so no computerisation, screen or any of that stuff that would befuddle me anyway, just servo reverse and elevon mixing. I couldn't cope with all that telemetry stuff.!

Martin

Kim Taylor26/08/2019 16:39:26
274 forum posts
53 photos
Posted by Foxfan on 26/08/2019 14:38:42:

Kim,

I didn't ask about a Wot4, btw. I hate them! Ugly pigs.

Martin

Sorry, self inflicted confusion compliments of the River Spey!!party

If the info on the motor doesn't give some indication of maximum amps or watts, I'd be wary of buying it.

Maximum amps is a pretty fundamental figure which the user HAS to know or risk burning the motor out.

All i.m.h.o. of course.smiley

Kim

Bob Cotsford26/08/2019 17:56:59
avatar
7931 forum posts
436 photos

Yes, the specs should either state max amps or watts, and ideally it should state whether those are continuos ratings or for example 15 seconds. There's a lot that's a compromise and/or approximation with electrics, and generally we start from the expected weight of the model and how it will be flown. I'm sure there's something on electrics for beginners to be found in either the electric power or beginner forums.

Foxfan26/08/2019 19:18:47
avatar
800 forum posts
6 photos

I'd better go searching for that, Bob.

I've just spent the afternoon counting my 5s, 2s and 1s and I can afford a s/h 4 stroke! Now all I have to do is find one, a smaller one. I will, I think have a mixture of aircraft, some electric (probably more) some IC, to go with the engines I have (and the dreamed of 4 stroke!)

Martin

Foxfan26/08/2019 19:41:23
avatar
800 forum posts
6 photos

Kim, I was thinking probably all the mentions of 4-Max had put a Wot 4 in your mind.

As it happens the club trainer is a Wot 4 and I made arrangements with our instructor to learn on it this morning. Oh well it looks easy to fix!

Martin

Bob Cotsford26/08/2019 20:59:25
avatar
7931 forum posts
436 photos

See if this link works

Foxfan26/08/2019 22:09:51
avatar
800 forum posts
6 photos

Thanks, Bob. I'll read that tomorrow morning before the Memsahib rises and all is quiet.

Cheers,

Martin

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of RCM&E? Use our magazine locator link to find your nearest stockist!

Find RCM&E! 

Support Our Partners
Addlestone Models
Wings & Wheels 2019
electricwingman 2017
Slec
CML
Cambridge Gliding Club
Pepe Aircraft
Gliders Distribution
Advertise With Us
Sarik
Latest "For Sale" Ads
New Poll - Sticky situations...
Q: How often - when using superglue - do you end up with it on your fingers?

 Every time
 Occasionally
 Sometimes
 Rarely
 Never
 Wear rubber gloves

Latest Reviews
Digital Back Issues

RCM&E Digital Back Issues

Contact us

Contact us