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Crossing over to the Dark Side

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Dai Fledermaus25/06/2012 08:17:16
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1057 forum posts
52 photos

Hello Fellers, I really would appreciate your advice.

I outlined in a previous thread, a month or two ago, that I was returning to the hobby after a 40 year absence. At that time I cut my teeth on control line models and diesel engines but now wanting to try my hand at RC, I had planned to build a Tyro Major with an IC engine because ARTF just doesn’t do it for me. A number of you were kind enough to reply with words of encouragement.

Since then I have felt increasingly drawn to the Dark Side – it’s a pretty dark subject for me at least and that is electric flight. I can see all the advantages, but I don’t really understand it. I always though Lipo was some sort of surgical procedure for fat people.

I’ve ordered a plan for a 52” span Basic Trainer for electric power called Versatility published recently in Radio Control Model Flyer. Yes magazines other than RCM&E are available. This high wing 3 channel with trike U/C is designed to fly quite slowly to give old geezers like me a fighting chance according to Ian Stockdale the designer. With a change of wing it also turns into a 4 channel intermediate trainer with ailerons.

There is also a low wing tail dragger version with ailerons on the same plan should I ever get to that stage. For the time being if I can get the basic version off the ground and back again without bending it, I’ll be more than happy

My problem is that a motor equivalent to a 20 size glow motor is recommended and I quote from the equipment list “ i.e. one drawing around 300-400watts and 900KV drawing around 30Amps” A Fusion FS3545/05 is suggested, but as far as I can see this particular motor is rated at 1100KV. Does this matter? Also this motor seems fairly cheap at about £30 when compared to say an E flight or an OS motor at about £55 to £60. Usually, but not always, you get what you pay for I’ve found. Unfortunately the weight for the 3 channel version is not given although the low wing 4 channel job is given a target weight of 3lb 12 oz. An ESC of 40A is recommended with a 3sx330mAh lipo.

Which motor would you get if you were me, and if you have any other helpful advice I would appreciate it.

Colin

GrahamC25/06/2012 09:08:06
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1240 forum posts
196 photos

Colin. With many brushless motors (but not with all) the number indicates diameter and length in mm. So a 3545 is 35mm in diameter and 45mm long.

The Kv rating indicates the rpm per volt. At this size of motor a 900Kv is a fairly low reving wind designed to turn a big prop slowly. (as opposed to a small prop quickly) In practice using an 1100Kv as opposed to a 900kv might mean a change of prop but it will probably work.

I've never used a premium electric motor, and before long you will discover that the motors at the mid to budget end of the market all look very (suspiciously) similar.

So for example, - looking at slightly bigger motors, this at the budget end of the market is very similar (in my opinion) to this at more mid market price, or even this at a higher price again.

In this case you might get what you pay for, not in the motor, but in terms of advice and support (and normally a spare shaft with the mid priced motor.) The final example will probably give you advice if you ring them, and sell you motor, ESC, Lipo and prop to suit your model, and they might help you if you have problems - so you get what you pay for. The first company are cheap, and good, but very limited when it comes to support.

I wouldn't go for the expensive stuff. I've never even seen an OS brushless so I can't really comment. I'm sure they will be very good indeed, but cheap motors are normally very good so....

In terms of advice, most of my electric purchases have been informed by the feedback on the items. I look for someone who has done roughly what I want to do and see what they used.

In terms of batteries, I have actually had a more expensive brand fail, and my cheap and cheerfuls have been fine. So again its not quite as simple as 'you get what you pay for.'

Hope this gives you something to help!

Graham

FlyinBrian25/06/2012 09:10:30
612 forum posts
4 photos

While it is true you usually get what you pay for most economy brushless motors are very good.

Something like this would probably suit Here

Dont forget you will need a decent charger, 12V versions are available for under £30 and dual mains/12V for around £60

Get yourself at least 3 batteries so you can get plenty of flying in, one battery flying, one ready to go and one on charge. I have found Gens Ace and Loong Max to be good budget Lipos.

Good luck

Andrew76725/06/2012 09:23:25
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809 forum posts
4 photos

Hi Colin

Some very good advice from Graham there. I started with an eflite 25 as this was the easiest way to match i.c but my eyes still water at the price i paid. Have a look at the 4-Max website as they have an equivalents chart. You can use this to either buy a motor from them or use their model number and match it to a Turnigy or an XYH/EMP from Giant Shark or Robotbirds as these motors are pretty much the same thing and save yourself some money. Like Graham i wouldn't bother with expensive items as there is enough information on the forums to point out which brands to avoid.BTW Turnigy Plush and Hobbywing Pentium/Flyfun are good escs for the price.

Best of luck

Andrew

Alwyn Gee25/06/2012 09:24:32
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194 forum posts
4 photos

I agree with what has been said already, I have some E-Flite RTFs with their own motors fitted and I have in the past paid the premium price for motors from them to fit other models that I have put together myself but I have also used the likes of KMS Quantum motors in a couple of IC conversions which were half the price of equivelent E-Flite and are still giving great service after two years. I've also used the JP Energy Pro motors with good resuslts. E-Flite and OS motors may be better quality than some of the mid range motors but they are certainly not twice as good as the price would imply.

Alwyn

Andrew76725/06/2012 09:25:36
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809 forum posts
4 photos

Ooops...Didn't see Flyinbrians post...Yes both Loong Max and GensAce are very good,outperforming some other more expensive brands.

Andrew

Josip Vrandecic -Mes25/06/2012 11:22:21
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2993 forum posts
260 photos

Dear Colin,I was hard core supporter of the IC systems(As a former F1C free flight champion)...but after discussion with moderator Tim Mackey,I was started using e-drive ,one year ago.This was the first time, (for me)I heard the term "dark side",by my forum friend Stephen Grigg.....lol.Today I use both systems,and I think that that the RC modeler must use all options,because You never know what brings happiness and satisfaction. face 1

All the best

Cheers

Jo

 

Edited By Josip Vrandecic -Mes on 25/06/2012 11:23:52

Dai Fledermaus25/06/2012 13:03:55
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1057 forum posts
52 photos

This is very helpful - thank you. I’m surprised by how inexpensive some of these motors are.

I had contacted George Worley at G-Max to ask him to recommend a motor,ESC, Lipo combination, but he keeps on asking for the maximum size of prop the model will take before he can recommend a motor suitable i.e. he’s asking for the distance between the centre line of the motor and that of the front wheel . At the moment I can’t do that because the plan hasn’t arrived. I’ve given him all the other information I have including the weight and the recommended prop dia which is 9”x 5” He says “He’s not interested in what the designer recommends” because “They ( 4-Max ) always try and fit the largest dia prop as these are far more efficient than a small one revving high, they also provide more thrust” Call me dense if you like, but I just don’t get it. It’s a good way of keeping the grass short on the flying field I grant you, but is the biggest possible prop for any model always fitted? I don’t think so.

Things were much simpler with my old AM25

Cols

Andrew76725/06/2012 14:16:53
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809 forum posts
4 photos

Hi Colin....George is right so hang on for the plan. I too found it strange at first moving from i.c but a .20/25 size electric motor can easily spin a prop that you would normally fit to an average .46 i.c. This is probably overly simple and others on this forum can offer a fuller explanation but never the less it works. Stick with it, you will understand when you've done a few....and once you move into the bright side, you'll never go back into the shade!!smile p

Andrew

Edited By Andrew767 on 25/06/2012 14:17:34

Tim Mackey25/06/2012 14:54:37
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20920 forum posts
304 photos
15 articles

Cant agree that that advice is right m'self - sometimes the model design and desired flying style needs a small fast revving prop, so its wrong to generalize IMO.

I do in principle agree that larger props are more efficient, and quieter as they work at lower revs.

I would suggest a power train of around 400 -500 Watts for your model Colin, and a 10 or 11"" prop, so a budget 1100 Kv motor would be something like THIS.

On 3s ( which is a popular size of battery ) you should get somewhere around 450 -500 watts.

I have propped this motor up to 12" @ 40A and it performed well.

50A or so ESC with BEC should be fine.on 3s.

PatMc25/06/2012 21:31:50
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4385 forum posts
524 photos

Colin,

I think you'll find that the Purple Power, Thumper & XYH motors are all badged versions of the same Turnigy motor at different prices. IMO the KV may be a little low for your needs unless you can either use at least a 12" prop or go to 4s lipo. I have an XYH3548/900 in my Magnattila driving a 12x6 using 4s lipo taking 460W at 31A , on 3s it's 280W at 25.5A.

There is an 1100V version of the XYH 3548 that should be more suitable if the prop dia is limited to 9" or 10". I haven't used one so can't quote any performance figures.

I'm using 2 of the Keda motors that Tim suggests in motor gliders using 3s lipo driving 11x8 folders for 330W at 30A. IMO the Keda is smoother running & has a more robust 5mm shaft against the 3548's 4mm shaft.

I think the E-Power 2826 in FlyingBrian's link is also a better option but unfortunately out of stock. I have one of these in a Druine Akrobat - 4s lipo, 10x7, 470W, 32A. Tested with 3s lipo , 11x7, 290W, 26.5A.

If your model comes in at the predicted weight of 60oz I think 280W will be adequate for a good performance. That's the equivalent to the realistic power of a decent 20 - 25 ic motor.

You might find it worthwhile downloading this Electric Flight Database to see what other forum members are using in a wide variety of models.

Dai Fledermaus28/06/2012 10:01:02
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1057 forum posts
52 photos

Thanks for your help everyone. The fog is starting to clear - a bit.

I guess it will make more sense when i get the project started

Colin

IanR30/06/2012 00:00:54
780 forum posts
4 photos

Pat

Purple Power, Thumper and XYH are all the same Turnigy motors? I mean, really, are they? Do you know this for sure?

Ian

moorer30/06/2012 00:47:37
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206 forum posts

Well,according to Giantcod/shark,XYH are the manufacturer of all of these motors including Turnigy and Wasp (also known as Strong Power) but, who knows? and do we really care as long as they work and they are CHEAP!! .....

Frank Skilbeck30/06/2012 08:23:21
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4684 forum posts
101 photos

Colin, if you are reasonably computer literate then download one of the motor programs, e.g. www.drivecalc.de they let you put in motor, battery and prop size and then calculate, rpm, current, thrust and speed.

It's a good way of comparing different combinations..

PatMc30/06/2012 12:43:37
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4385 forum posts
524 photos
Posted by IanR on 30/06/2012 00:00:54:

Pat

Purple Power, Thumper and XYH are all the same Turnigy motors? I mean, really, are they? Do you know this for sure?

Ian

The detailed specifications quoted in retailers adverts for many motors of the same size often seem to be cut & paste from Turnigy's originals. The motors themselves often have identical cases, except for the colour.

Motors made by other manufacturers are or have also been sold under different badges. For example I have 3 types of Overlander "Tornado" inrunners that AFAICS are made by Himax.

Pat.

IanR30/06/2012 12:59:49
780 forum posts
4 photos

Thanks Pat, Moorer,

Pat, I think that the fact that you've found a (Keda) motor that has a more substantial shaft, at 5mm as opposed to 4mm, may be a more significant factor in motor choice.

E-Flite motors are more expensive, but are they worth it?

Ian

PatMc30/06/2012 15:40:09
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4385 forum posts
524 photos
Posted by IanR on 30/06/2012 12:59:49:

Thanks Pat, Moorer,

Pat, I think that the fact that you've found a (Keda) motor that has a more substantial shaft, at 5mm as opposed to 4mm, may be a more significant factor in motor choice.

E-Flite motors are more expensive, but are they worth it?

Ian

IMO - no. I don't see that they are in any way superior to the cheaper options.

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