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An Eleccy WOT4XL - with a twist!

An electric conversion of an electric conversion of an IC model!

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stevan Lewis 119/09/2018 17:09:50
59 forum posts
2 photos

BTW BEB, the spinner looks like the Turnigy Turbo spinner from Hobbyking, they have cap head bolts.

Steve

Biggles' Elder Brother - Moderator19/09/2018 17:28:18
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Thanks for that info Steve. I do like that arrangement.

BEB

Biggles' Elder Brother - Moderator19/09/2018 18:08:49
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So, today was supposed to be "ESC fitting day" - but when I got into the shed I realised that I was just dodging a job here. You see doing the ESC is easy, sorting the battery isn't!

"So let's all go and do the ESC?" No, let's be grown up, grasp the nettle, and sort this battery. I can't properly site the ESC, with the right length leads etc., until I know where the battery is going to be anyway!

Basically its going in here:

wot4xl-16.jpg

The fuel tank bay. I'd love to get it right up in the cowl - but it's just not possible. The cowl is too narrow and there is no space between the standoffs etc. So the fuel bay it has to be.

For some reason there is a whopping big thick chunk of hairy balsa there - epoxied in. Oh joy! I don't know why, it only held the old ESC which, although large, wasn't that heavy! I need to get this block out, its taking up space I want to use for something else.

Boy it was a job and a half! It was stuck in there never to come out and of course access was tricky. But a combination of a scalpel, stout knife for levering and eventually a pair of long nosed pliers finally won the day!

wot4xl-17.jpg

I have it back as it was originally!

So, why am I so concerned to lose this block? Well, after much squinting and eyeing up, I think that if I cut a hatch in the top of the black covered fake windscreen I could get a 6s battery in though there! It couldn't be a long hatch, or wide, but it is deep giving us maneuvering space. So battery nose down first and than wiggle it into position. If that works there would be no need to take the wing off to change the battery!

So I marked out the position of a hatch on some masking tape over the "windscreen":

wot4xl-18.jpg

Took a fresh scalpel blade and a very big breath,..... and started cutting - the moment of commitment. You have to do this very gently I find, using very many light strokes - you don't want to dig in. I was surprised at how thick the top wood was, I had to swap over to a longer scalpel blade at one point. But eventually I got there!

wot4xl-19.jpg

And here is the hatch cover,... basically the cut out piece!

wot4xl-20.jpg

You can see how thick it is. I now need to trim that a bit - it's a very tight fit! - and fit some pegs and catches to retain it.

Does it work? Can I get the battery in? You bet yer!!

wot4xl-21.jpg

You could hold a dance in there!

So, pleased with that, once we get it fitted probably we can look at battery retention but I don't foresee any big issues there.

Phew! Time for a bottle of Spitfire I think and a nice sit down!

BEB

Ron Gray19/09/2018 18:41:15
1050 forum posts
273 photos

C’mon BEB, my standard size WOT4 has 6 cell batts in it, the XL should swallow them! (yes I know mine are only 3000Mah). I made a battery tray that allows the batt to be slid in and out, much like the leccy conversion but longer.

Devcon119/09/2018 19:21:47
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1311 forum posts
438 photos

Not at all disappointed about no twist as the suspense would have been too much for me.

We must be telepathic as I'm at a very similar stage on a standard Mk 3 build hence following with interest.

I notice from the instruction that Chris Foss advocates, for those brave enough, an option to cut rectangles out of the foam cores to remove some excess baggage. Not sure if this is referenced for it's bigger brother.

Kim Taylor19/09/2018 19:47:45
196 forum posts
53 photos

No foam wings on an XL, like its normal sized artf sibling, it's a built up wing.

Kim

Geoff Sleath19/09/2018 20:06:53
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218 photos

That IS a thick piece of balsa but, presumably, fairly soft balsa? That's LOT easier than removing the wing each flight for 'refuelling'.

I know I'm obsessed with getting batteries as far forward as possible but couldn't you neaten up the hole in the firewall so you could push battery through if needed to get the CoG right?

Geoff

Biggles' Elder Brother - Moderator19/09/2018 21:15:10
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I have looked Geoff, believe me I'd like to get the battery up there as well. But the frontal area on the WOTTY is surprisingly small, this means the standoffs are very close together - at motor spider pitch - and there isn't really much opportunity to build a two stage mount with a wider forst stage because of the small area. I think we are stuck with what we have. I don't think the battery will be far enough forward to eliinate all the lead, we may still end up with at least a little.We'll see.

One thung about this model is it's built for IC and its an old design, so it's massively over engineered for electric power. The wood in the structure is thick and heavy. More modern IC models are made of CNC cut interlocking ply. This gives them the strength to withstand the vibration of IC without the bulk and weight. Compared to them this aeroplane is rather "agricultural" in design!

BEB

Edited By Biggles' Elder Brother - Moderator on 19/09/2018 21:15:37

Edited By Biggles' Elder Brother - Moderator on 19/09/2018 21:16:49

McG 696919/09/2018 21:29:39
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Just very probably a totally daft 'novice' question again, BEB.

... but that fuse is looking huge on your pics, so wouldn't it be possible to enter the Lipo more 'vertically' just behind the firewall???

If that's physically possible, or even being 'tilted' at the maximum available angle, the battery's CoG would be closer to the front than in a full horizontal position.

... I guess I'll just grab my coat now. blush

Cheers

Chris

Biggles' Elder Brother - Moderator19/09/2018 21:56:47
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It's a good question/suggestion Chris - but sadly my lipo's are just about10-15mm too tall if placed at the front. They might fit further back, but then there would be no advantage over just laying it flat. sad

BEB

McG 696919/09/2018 22:09:15
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Well, at least, not totally daft then, BEB.

Even if it doesn't help you much further. sad

Cheers

Chris

Biggles' Elder Brother - Moderator19/09/2018 22:21:07
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Suggesions are always welcome Chris!! Ideas from members of this forum has saved my bacon on more than one occassion! smile

BEB

Bob Cotsford19/09/2018 23:49:34
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7462 forum posts
421 photos

Since converting the WotsWot to electric I've started using the tray system from that for all my 6S models. Would that help by a) mounting the battery at an angle effectively bringing it forward a smidgeon and more importantly b) make it easier to fit the battery with no scrabbling around for velcro straps inside the nose? I hate those straps with a vengance, it's like trying to tie knots in live eels using just two fingers. Not that I've tried that you understand, honest!

Geoff Sleath20/09/2018 00:08:21
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Posted by Biggles' Elder Brother - Moderator on 19/09/2018 21:15:10:

I have looked Geoff, believe me I'd like to get the battery up there as well. But the frontal area on the WOTTY is surprisingly small, this means the standoffs are very close together - at motor spider pitch - and there isn't really much opportunity to build a two stage mount with a wider forst stage because of the small area. I think we are stuck with what we have. I don't think the battery will be far enough forward to eliinate all the lead, we may still end up with at least a little.We'll see.

One thung about this model is it's built for IC and its an old design, so it's massively over engineered for electric power. The wood in the structure is thick and heavy. More modern IC models are made of CNC cut interlocking ply. This gives them the strength to withstand the vibration of IC without the bulk and weight. Compared to them this aeroplane is rather "agricultural" in design!

BEB

So, do away with the stand-offs and build a smaller ply mount with a bigger 'firewall' at the end to suit the motor?

Just thinking aloud without the benefit of actually seeing problem in real life. I know I'm teaching my Granny to suck eggs (not that I ever saw her doing that).

Geoff

Shaun Walsh20/09/2018 06:11:00
61 forum posts

I know it involves extra expense but could you fit 2 lower capacity 6s batteries in parallel or 2 3s batteries in series vertically right up against the firewall it looks like you have enough room for 2 batteries side by side they just need to be short enough to fit under the hatch?

Biggles' Elder Brother - Moderator20/09/2018 06:44:15
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Thanks for all the ideas chaps - brilliant stuff.

Bob - yes I did the sloping battery tray trick with my Chipmunk conversion, so that might well help and I'll certainly have a look. As you say the impact on the CoG would be very small, but the convienience, in terms of getting the battery in/out and snuggled down securely, is potentially considerable.

Geoff - the fundemental problem is even if I could open the space by re-designing the mount and just about get the battery in betwen the actual firewall and a back plate to the motor it would have to be vertical - I've recently done exactly that on a BlackHorse Sea Fury. But in this case the battery is taller than the depth of the cowl so it wouldn't fit! I never really realised hown much the front of a WOTTY tapers. The bottom of the fuselage comes up quite sharply and that line is continued by the cowl itself and so you end up with a surprisingly small cowl and frontal area for what is a fairly "chunky" model!

Shaun - I don't have any higher capacity 3s batteries, but I do have a number of 6s 3000mAh batteries and two of them in parallel to make a 6s 6000mAh might well be a possibility as they may be short enough to go vertical against the firewall - thus reprising Chris's idea above. I could also slightly stagger them in the stack - as I say the floor slopes upward to the front in a taper. I shall look at that as well.

Thanks again chaps - all ideas much appreciated.

BEB

Martin Roberts20/09/2018 09:34:36
87 forum posts

Hi BEB, very interesting so far....pick up price - very enticing

Nigel R20/09/2018 10:23:24
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" even if I could open the space by re-designing the mount and just about get the battery in betwen the actual firewall and a back plate to the motor it would have to be vertica"

how about,

ditch the standoffs; build a ply motor box - larger than the lipo - sides of this box to extend back to wing LE if needed for strength

cut a big hole in the existing firewall, the size of the motor box

the lipo can slide forward into the motor box, almost up to the motor then, while laying horizontally

ESC can be strapped to underside of the box, in the cowl

Excuse the quality of my top view diagram:

box top view.jpg

Biggles' Elder Brother - Moderator20/09/2018 12:47:27
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I have been spending some of this morning fiddling with different battery arrangements and combinations.

The two 6s 3000mAh solution won't go, basically I can't get two packs through the hatch and even if I could, while they are each slightly narrower than a 5000mAh they are not much shorter.

I thought I'd include a few photos of the battery in context so you can see the issues better. Sorry these are not wonderful quality but they were taken on my phone held and operated in one hand while my other hand held the battery in place!

The first picture shows why the battery can't go vertical in the cowl:

wot4xl-22.jpg

And the next photo shows that it can't go upright in the fuel tank bay either:

wot4xl-23[1].jpg

Now it could go on a slope - as Bob suggests:

wot4xl-24[1].jpg

wot4xl-25.jpg

So far that looks my best option.

Your suggestion is good Nigel, I have done something very similar to that previously - see the photos below. I started with a motor box:

chippie 8.jpg

Then cut a big hole!

chippie 14.jpg

And installed a "poke through into the cowl" sloping battery chute:

chippie 24.jpg

chippie 26.jpg

The problem is,...call me lazy,....but it is a lot of extra work for a winter hack!

If I end up with the CoG too far back and need too much lead I can revisit this and do it if I have to. But for now I'll hold that in reserve!

BEB

Edited By Biggles' Elder Brother - Moderator on 20/09/2018 12:50:28

Kim Taylor20/09/2018 16:36:48
196 forum posts
53 photos

I did something similar to your 'sloping' option on mine

dsc_0057.jpg

As you can probably see, I also positioned the esc on the motor stand offs to get the weight forwards and it pretty much balanced (complete fluke).

I did my top hatch the same as the 'normal' size Wot4 artf, i.e. I sliced the whole 'windscreen' area off after carefully cutting down the relevant bulkheads, but your way is doubtless stronger.

Still watching with interest - I'm beginning to wish I'd persevered with mine now, rather than going over to petrol.

At least the battery hatch made it easy for me to place the cdi unit and battery.

Kim

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