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Author Topic: Recommendation for SMALL brushless....  (Read 10403 times)

dodgy geezer

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Re: Recommendation for SMALL brushless....
« Reply #50 on: August 11, 2009, 01:25:37 AM »

That makes sense, and would explain the difficulty in setting low speeds. I find that the throttle signal gets quite touchy, and if the ESC loses synch it has to restart with a little surge before coming back down to the bottom end speed again. So about 1000 rpm is a practical limit with sensorless - Nick-75au is doing well to run at 600!

From the weight and space point of view, 4 NiCads would be better than 6. I have seen 4 Nicad cell escs advertised, though, as you pointed out, never 2!

I would normally have gone brushed with a bec esc, but I became interested in brushless because:

1 - the price seemed to be very low; I could not get a brushed motor and ESC for 12
2 - if I can rewind a CD-Rom prices become even cheaper
3 - in small boats the small size and weight of a brushless motor is an advantage
4 - small EeZeBilt boats never had planing performance. Brushless motors would offer that
5 - small boats cannot carry big batteries, so suffer from endurance problems. High efficiency would help that. 

I imagined a small light boat cruising at a good non-planing speed for a fair time on 4 2200MAH NiCads or NiMH, and being able to shoot up onto the plane a few times - the whole thing for pocket-money prices. No complex charging regime or expensive power packs. In fact, I think we're most of the way there - the ability to go dead slow is not absolutely critical. Getting a good low-drain efficient run is important - this will depend on the prop as well as the motor, of course...
 
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Proteus

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Re: Recommendation for SMALL brushless....
« Reply #51 on: August 12, 2009, 03:55:31 AM »

you can get cheap, small  brushless speed controllers with reverse, and the work OK


http://www.r2hobbies.com/proddetail.php?prod=rcps81707_30


Proteus
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FullLeatherJacket

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Re: Recommendation for SMALL brushless....
« Reply #52 on: August 12, 2009, 08:40:57 AM »

Delivered price to UK is $38.05 = 23.19; you'll probably avoid the VAT, which should be on top of this. If HMRC do spot it and the Royal Mail have to collect then say cheerio to 15% VAT plus an eight quid "handling charge" from Postman Pat. A useful link but even tax-free it's a bit outside the parameters of 12 including the motor.

I'm still not sure if the objective here is primarily a cheap power train for an Ee-Zee boat, simple enough for kids to fit, or an experiment with brushless motors. If it's the former then it's a no-brainer; brushless just isn't there yet - certainly on the parameter of price. I would also be reluctant to accept that an average 12-year old might be capable of rewinding a CDROM motor when a fair proportion of adults seem incapable of wiring up a battery the right way round - even with a coloured diagram to show them how it's done.

Cynical? Moi?? Nope - just sadly wiser than I used to be.

FLJ
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kiwi

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Re: Recommendation for SMALL brushless....
« Reply #53 on: August 12, 2009, 09:13:09 AM »

Brilliant FLJ
But how true.

Even if I think DG is going in the right direction

vnkiwi
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stallspeed

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Re: Recommendation for SMALL brushless....
« Reply #54 on: August 12, 2009, 09:43:00 AM »

Now that I've had a look at the photos,I'm sure I have seen something similar to the 10 1/2 inch Terrier.
It was fitted with a 540 motor,7.2 racing pack and servo op. microswitch.Far from sinking the model,the 540 allowed it to skim along like a tunnel hull boat.
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dodgy geezer

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Re: Recommendation for SMALL brushless....
« Reply #55 on: August 12, 2009, 09:57:26 AM »

....
I'm still not sure if the objective here is primarily a cheap power train for an Ee-Zee boat, simple enough for kids to fit, or an experiment with brushless motors....
FLJ

Well, it's both, really. While I have been wasting my life away from modelling technology has changed a bit, and when I (was encouraged!) to put up a few pages in memory of the EeZeBilt range I wasn't sure where it would go. I couldn't work out if brushless would be a cheap possibility without a bit of experiment...

What I can see happening is a development in two directions. I would like to maintain and distribute data on the old EeZeBilt kits as a historical service. That means producing (saving!) original die-cut sheets and artwork where possible, and maybe some research later. All contributions gratefully received, by the way - I have Triton diecut sheets up, am working on reconstructing the sheets from a 1960s Terrier, and have a promise of a Curlew to come. If you want, you can now reproduce an original model from 12"x3" balsa, a cheap motor, a 4.5v battery, some brass tube and paperclips....

But a major feature of the EezeBilt kits, and others of this kind from Veron and elsewhere, was that they introduced young kids to the hobby cheaply. So it would be good to encourage that as well - several people have stressed that we have a gap in this area. Simply putting up the original die-cut sheets is of limited value to kids who aren't so interested in the history, because:

- People get different sized balsa today - why cut it down?
- You can't get the original propshaft/rudder
- You can get much better power units
- You can get cheap'ish' radio

so I thought I would see how we could 'improve' the range to offer what it used to do - a simple cheap introduction to model boating. This will be the '50+' range that I have been trying out - EeZeBilts for the 21st century! I would expect these to:

- Cost about 5 in materials
- Maybe another 5-10 for motor and battery
- Be big enough to carry lightweight radio
- Be just as easy to make, using the original EeZeBilt eggbox technique
- Be between 15"-20" rather than 10"-17"
- Offer lots of opportunity for simple mods and self-built accessories
 
These are probably where the brushless motors would come in. What I think I have found is that we are quite close - some end-of-line BL motors and escs are around the cost bracket, but cheapness rather rules out LiPos (with their costly chargers) and size limits the number of cells. So we are at one edge of an envelope. Which is always fun...


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dodgy geezer

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Re: Recommendation for SMALL brushless....
« Reply #56 on: August 12, 2009, 10:38:26 AM »

Now that I've had a look at the photos,I'm sure I have seen something similar to the 10 1/2 inch Terrier.
It was fitted with a 540 motor,7.2 racing pack and servo op. microswitch.Far from sinking the model,the 540 allowed it to skim along like a tunnel hull boat.

Sounds a bit like a shark - the boat will stay above the water so long as it's moving forward...!
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Proteus

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Re: Recommendation for SMALL brushless....
« Reply #57 on: August 12, 2009, 01:52:51 PM »

Delivered price to UK is $38.05 = 23.19; you'll probably avoid the VAT, which should be on top of this. If HMRC do spot it and the Royal Mail have to collect then say cheerio to 15% VAT plus an eight quid "handling charge" from Postman Pat. A useful link but even tax-free it's a bit outside the parameters of 12 including the motor.

I'm still not sure if the objective here is primarily a cheap power train for an Ee-Zee boat, simple enough for kids to fit, or an experiment with brushless motors. If it's the former then it's a no-brainer; brushless just isn't there yet - certainly on the parameter of price. I would also be reluctant to accept that an average 12-year old might be capable of rewinding a CDROM motor when a fair proportion of adults seem incapable of wiring up a battery the right way round - even with a coloured diagram to show them how it's done.

Cynical? Moi?? Nope - just sadly wiser than I used to be.

FLJ


I read the thread and saw he was after a reversing brushless speed controller but was told in reply 28 that brushless speed controllers don't have reverse so I was pointing out that you can and they are cheap .

Sol how many people who have bought from this sort of company small items have had to pay VAT, I have bought lots and never had to, he also sells them on e-bay.

Proteus
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dodgy geezer

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Re: Recommendation for SMALL brushless....
« Reply #58 on: August 12, 2009, 03:53:53 PM »


I read the thread and saw he was after a reversing brushless speed controller but was told in reply 28 that brushless speed controllers don't have reverse so I was pointing out that you can and they are cheap .

Sol how many people who have bought from this sort of company small items have had to pay VAT, I have bought lots and never had to, he also sells them on e-bay.

Proteus


Well, reversing would be nice. But originally, what I said was

"I thought there might be a lightweight aircraft brushless and ESC for perhaps 10-15 which would make it plane on 4 cells. Has anyone got any advice...."

I was looking for small, light and cheap. 4 cells turns out to be a bit of a problem for brushless, but there are cheap combos available as offers - 12 for a motor+esc was a good example. Once I get a cheap prop-shaft and connector I will be trying it out.

My understanding for purchasing abroad is that the magic number is 18 - the cost of the item must not exceed this. Once it does, you are liable to be assessed for tax, on the cost of the item + postage! In practice, single items frequently come through a bit higher without attracting attention, but this must depend a lot on the person on duty, whether a new policy is being enforced, and luck. I have never paid any extra tax yet, and have had items of around 30 delivered.

I suspect that if you go for specialist shipping you are more likely to be stung - I have heard stories about DHL and others in the past. The problem is that, as well as charging an import duty, your shipper is also allowed to charge you an administrative fee for collecting this money from you and passing it onto Customs. This is usually unspecified beforehand unless you ask about it, and, for a grasping commercial company it can be quite high! Royal Mail will also charge this admin fee, but the postie is usually uninterested in collecting it - they don't like the extra work involved in handling money. I have had a package with a 'money to pay' sticker just pushed through my letterbox while I was out, and no one came round later to collect anything...

There's lots more compexity, but you get the idea....


 

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