What WOT 4 (ARTF electric)?

[jeffrey cottrell]

Hi Guys

Thanks to everyone who ventured an opinion, but I'm not sure if it answers my question.
I originally asked whether a 3s 1185 Kv would be enough to power the 52" Wotty, and the general consensus seems to be 'only just' if at all.
Given the power train will be lighter as well, I'm back to the old problem of a light model with big wing area and limited power struggling in the wind.
So, I'm leaning towards the 43" version, but that's where I opened a can of worms.
Trying to find a wing chord, so I could get approximate wing loading, so I toured the internet looking for a shop that could measure it for me.
Couldn't find one, but I did find differences in the specs according to who I looked at.
One shop said Span of 43.1" and fuz length of 41.5".
Another said span of 47" but same fuz length. The 47", I believe is the foamie.
No more foam for me, explain why in a minute.
So, 4" bigger span but same fuz length sounds wrong to me.
Tried to call Ripmax direct but no-one answered the phone.
On the Ripmax site I did find a picture of the kit contents taken from directly above, so I scaled up the dimensions from that.
Using a span of 43" as a baseline gave me a chord of 8.16" which sounds about right, but scaling up the fuz length came out at only 33" or so.
The Ripmax site also gave the o'all weight as 50.5 oz, or 3.15 lb however given the discrepancy with the fuz length, not sure if I trust this either.
So, did some static tests with my Limbo Dancer using the same prospective power train.
Tethered down WOT consumption measured at 48a.and voltage at 11v. This gives an overall wattage of 528. Bob, I believe you predicted 490, so you win first prize.
Using the quoted weight, that gives 167 w/lb. That should scare the horses.
Not sure how much credence should be given to this. I only use full power for verticals, and most of the flight is spent a 1/3 throttle or less.
Flying for a set time and then measuring how much the charger puts back in gives an average real-time current of 18a or so.
That's a more realistic figure I believe.
Also, using the chord I scaled up from the photo, gives me a wing area of 2.47 sq ft
and a wing loading of 20.44 oz/sq ft.
So, conclusions:
W/lb sounds high to me, but it was based on unrealistic figures, and I can always fly throttled back. Wing loading sounds in the ball park. Maybe a little high, but one of my club members who has one reports it difficult to slow down for a landing, which would tend to support that.
So, I think the smaller one comes out on top, provided I can find one. If anyone has a 43" model and could check the fuz length that would help.
Other than that, your thoughts?
Oh yes, why no more foamies.
Took my WotsWot out for a play this morning. Bit windy for it but flew ok. Hit a wind gust on landing, caused a tip on to the nose. No biggy, everyone's done that.
Not so with mine. Broke the fuz clean in half just under the cabane mountings.
Might get repaired sometime, not sure yet.

Jeff

[Old Geezer]

Jeff, I've been away from this thread for ages, but in the interim I bought a Blue Wottie. I was never really happy with my BW, yes, it flew alright but somehow it wasn't the same as the larger artf airframes, it certainly "felt" heavier when I flew it and was definitely more difficult to get back onto the ground. I have a dreadful confession to make, I tip stalled a Wot4 - yes, the BW, on the downwind leg ( windy, turbulent - honest ) of the landing approach. Just dropped out of the sky like a grand piano. Fuselage beyond repair - well for me anyway - scrapped it. Wotties are funny planes, each one is different. My first built from a kit was brilliant and tough, and pretty lively on a cooking 40 ( Fuji, Enya etc ), my first artf went really well with a big Axi and a 4s 4500 under the wing ( much much easier to take off the wing rather than the later battery hatch set up ). My latest Wottie was a disappointment despite exactly the same motor - battery - prop set up. Eventually I resurrected an Irvine 46 and hung it on the front of Number 3 - apart from a bit of noise and a smudge of (synthetic) oil No.3 then went just like No.2, if you want to be picky the throttle response is a bit lethargic compared with an outrunner, that's all.

Your only problem will be finding an artf Wottie - having flown both the i/c:ep artf and the blue artf ep I would definitely go for the "dual fuel" airframe - and if you go for the ep option, as many watts as you can get, that wing will carry them. If going with a big LiPo you might change the battery mount and load it through the big 'ole under the wing - much easier.

Gurth.

[Old Geezer]

Jeff, I've been away from this thread for ages, but in the interim I bought a Blue Wottie. I was never really happy with my BW, yes, it flew alright but somehow it wasn't the same as the larger artf airframes, it certainly "felt" heavier when I flew it and was definitely more difficult to get back onto the ground. I have a dreadful confession to make, I tip stalled a Wot4 - yes, the BW, on the downwind leg ( windy, turbulent - honest ) of the landing approach. Just dropped out of the sky like a grand piano. Fuselage beyond repair - well for me anyway - scrapped it. Wotties are funny planes, each one is different. My first built from a kit was brilliant and tough, and pretty lively on a cooking 40 ( Fuji, Enya etc ), my first artf went really well with a big Axi and a 4s 4500 under the wing ( much much easier to take off the wing rather than the later battery hatch set up ). My latest Wottie was a disappointment despite exactly the same motor - battery - prop set up. Eventually I resurrected an Irvine 46 and hung it on the front of Number 3 - apart from a bit of noise and a smudge of (synthetic) oil No.3 then went just like No.2, if you want to be picky the throttle response is a bit lethargic compared with an outrunner, that's all.

Your only problem will be finding an artf Wottie - having flown both the i/c:ep artf and the blue artf ep I would definitely go for the "dual fuel" airframe - and if you go for the ep option, as many watts as you can get, that wing will carry them. If going with a big LiPo you might change the battery mount and load it through the big 'ole under the wing - much easier.

Gurth.

[jeffrey cottrell]

Hi Old Geezer

Certainly been a while since we spoke. Great to hear from you again.
Agree with what you are saying. If all things were equal, the full size Wotty would be my choice, probably built from a kit.
However all things are not equal (are the ever?).
First of all, I am recently retired so money is not as free as it used to be. Makes no sense to make the sizeable investment in a 4s set up, and leave brand new equipment in the shed gathering dust.
Also I have recently downsized, so storage space and build area are at a premium.
Mind you the whole discussion might be academic anyway.
As I understand it, Ripmax have recently moved their warehouse and ran down their stocks prior to the move.
Might be a while before any of the artf's are available. One shop is quoting March 2020. Don't want to wait until winter is almost over before I buy a winter hack.
Ho hum.
My next post might be to ask if anyone can suggest an alternative, similar size and layout, that might be more available

We'll see

Jeff

[Old Geezer]

Jeff, I know the feeling ( retired, fixed income, asset rich and cash poor!). If you're looking for a sub-40 sized Hack model, i.e. 25-32 i.c. or the e.p. equivalent, you could do worse than look at Pegasus' website - they have quite a few kits which can be either IC or LiPo powered in that size range, and being balsa with ply doublers and foam wings, they're pretty strong. The Wasp is on my list as it has the look of an old Mick Reeves "Gangster" about it! And if you wanted something a bit less demanding there's always a Uno-Wot.

Gurth

[jeffrey cottrell]

Hi Old Geezer

Thanks for the idea of Pegasus. They certainly do have quite a range, but nothing really floated my boat. especially when you look at how many they actually have in stock.
Did phone them to clarify something, and ended up having a long chat with a very helpful guy. He had a different take on why Ripmax has no stock. Sounded plausible to me.
Anyway, no help to me, guess I'll have to hold my nose and get a Riot.
Ho hum.
Being a 'glass half full' kind of guy I did see one advantage.
The Riot shares most parts with the Ruckus, which means I can buy one, airframe only, and transfer the gear from that rubbish Ruckus lying dead in my shed.
CenturyUK have an E-Bay site, so they can do me the airframe post free.
Turns a £159 mistake into a 'mere' £100 one.
That's my excuse anyway.
Meanwhile, had a look at the Wasp. see your point, definitely Gangster'ish.
Instead, wonder if you might have looked at one of these:
https://www.probuild-uk.co.uk/index.php?route=product/product&product_id=5130&search=bullet
So much prettier, imho.
Certainly when I get a build area sorted, a Mini Kosmo is going on the list:
https://www.pegasusmodels.co.uk/product.asp?type=&maingp=RC+Aircraft&prodid=1011705#.XWAytXt7mzc
That's a real model.

Jeff

[Old Geezer]

Shame about the non-availability of the artf Wot4s - had a look at the Bullet, it does appeal but a) when it first re-appeared the revue published in one of the comics was less than enthusiastic, and b) a Bullet with it's u/c hanging out in the breeze just looks wrong except when landing or taking off ( as does any warbird ) and our patch isn't exactly retractable u/c-friendly*. Anyway, I've promised myself a Wasp now as I've managed to pick up a 2nd hand 32 that should fly it very nicely.

* I know some folk will use the retractable u/c to get their pride and joy into the air (like a sailplane's dolly) then pull the wheels up and slide it in dead stick on it's belly, but I get the feeling that eventually it would all end up in tears.

[Bruce Collinson]

There are no ARTF Acrowots either. Apart from the one I bought from Just Kits at last weekends Winterton open day (flying the flag for the UKCAA). They had one at the shop and went back for it.

They had a Wot 4 too. Very nice helpful people, in Hull.

BTC

[Lima Hotel Foxtrot]

Posted by Old Geezer on 24/08/2019 08:51:22:

Shame about the non-availability of the artf Wot4s

Addlestone Model Centre have some in.

**LINK**

[Shaun Walsh]

Posted by jeffrey cottrell on 23/08/2019 19:43:27:

Hi Old Geezer

Thanks for the idea of Pegasus. They certainly do have quite a range, but nothing really floated my boat. especially when you look at how many they actually have in stock.
Did phone them to clarify something, and ended up having a long chat with a very helpful guy. He had a different take on why Ripmax has no stock. Sounded plausible to me.
Anyway, no help to me, guess I'll have to hold my nose and get a Riot.
Ho hum.
Being a 'glass half full' kind of guy I did see one advantage.
The Riot shares most parts with the Ruckus, which means I can buy one, airframe only, and transfer the gear from that rubbish Ruckus lying dead in my shed.
CenturyUK have an E-Bay site, so they can do me the airframe post free.
Turns a £159 mistake into a 'mere' £100 one.
That's my excuse anyway.
Meanwhile, had a look at the Wasp. see your point, definitely Gangster'ish.
Instead, wonder if you might have looked at one of these:
https://www.probuild-uk.co.uk/index.php?route=product/product&product_id=5130&search=bullet
So much prettier, imho.
Certainly when I get a build area sorted, a Mini Kosmo is going on the list:
https://www.pegasusmodels.co.uk/product.asp?type=&maingp=RC+Aircraft&prodid=1011705#.XWAytXt7mzc
That's a real model.

Jeff

I can recommend the Riot, have been flying one for about a year now and it has had a few heavy landings and visited two trees with only minor damage, it's pretty robust. The only niggle I have is that the battery box is pretty small, I had to cut away the bottom to fit a 3S 2200 in and the plastic clips either side of the hatch break easily, I reinforced them with thin piano wire epoxied behind them to act as torque rods.

Recently re-motored with a 4-Max 3541-1070 giving it about 400 watts it will climb vertically .

[Bruce Collinson]

Jeff,

Can you really not find a Wot 4? Modelshop Leeds had them in about a fortnight ago.

ProBuild, PB Crescent Bullet, almost certainly not in stock. I ordered one online about 15m ago and the order was refunded. My understanding at the time was that it's a smallish classic patternship, some way removed from a Wot 4 or indeed a Ruckus/Riot from what I've seen of those.

BTC

[jeffrey cottrell]

Hi Bruce

Thanks for your thoughts, but:

Agreed Leeds do have the Waot 4 kits in stock, but my question was regarding the ARTF versions, specifically the smaller 43" built up one.
These are distributed by Ripmax, who seem to be having an issue fulfilling orders at the moment.
If you happen to know of a shop that has that specific one in stock, I'm all ears.

The reference to the Crescent Bullet was in answer to a post from Old Geezer, who suggested Pegasus Models as a possible source of an alternative to the Wot 4.
In the post he mentioned the Galaxy Wasp model as being similar to the old Gangster.
I mentioned the Bullit as being also Gangster'ish, but a lot prettier imho. That's where it came from.

Jeff

[Bruce Collinson]

Jeff,

If I'm guilty of not reading backwards to the start of the thread then please forgive me; I can only plead full-time (self) employment in mitigation. My dim recollection was a requirement for an all-round hack.

Never having had the smaller Wotty, but on my third ARTF with the 4th awaiting reaching the top of the must-do list, hopefully before the third needs the hangar again, having had 2.5 foam versions (Wot Frankensteins), my initial thought was that the standard size ARTF is a far better overall option than either the smaller one or the foamie. Whilst they all have an undoubted place, the foamies fly worse with age, each time the Foamtac has to be applied, and I can't see the smaller one handling autumn and winter weather and grass strips.

I think everyone has kits, as I believe Chris Foss wholesales those, not Ripmax. I thought a decent batch of ARTFs from Ripmax landed about two or three weeks ago and that MS Leeds still had some, allegedly with some discolouration to the outer box as a presumed result of sitting on some Far Eastern quayside for too long (didn't do the full size Mosquito any good either). Certainly Just Kits in Hull had one on their stand at Winterton a week ago and as they have minimal web presence it's probably still there.

George Worley at 4 Max will spec the entire powertrain but the largest of his LiPos I can squeeze in mine (Wotty that is) is 4.5A, whereas an Overlander 5A will fit but is less tolerant of full-chat hooning as my firm belief is that George's C ratings are deliberately cautious. Still does 7 minutes of semi hooning all the same.

On my second Acrowot, there's a gulf of difference between the two and I suspect the Bullet and the Ruckus are closer to the Acrowot. I try to summarise the difference as being three seconds; that's the difference between how long either needs a positive control input to avoid gravity, terra firma etc. Wotty far more tolerant, high wing.

Hope you come to the right decision. Of course if you have the time and skills, both of which are in short supply here, you can do much worse than build one of Cross Fish's kits with lots of scope for beefing up the u/c plate, adding gratuitous GRP skinning etc.

Do keep us posted!

BTC

[Jonathan M]

Just an update on my 53" Balsa ARTF Wot4:

I now see that 4-Max has significantly upgraded their power-train spec for this model! **LINK** now with their 5055 595kv motor.

My current Wot4 is powered with their earlier spec smaller motor, the 3547 800kv, which is just adequate but has proved less than satisfying!! I still have the Overlander 4250 800kv from my original airframe which crashed on its fourth flying session (due to RF failure of my old RC transmitter) so I'm going to swap this back in.

Jon

[Jonathan M]

And another update - and a question.

The 4250 is back in, but with a power of 182W/lb I now find it too much for my taste! I was considering limiting the throttle (ESC) to 90% or thereabouts, so that it only pulls about 165W/lb, which is an easy enough thing to do. The previous motor, the 3547, only pulled 135W/lb which proved just that bit too weedy for the model (especially at our exposed site).

BUT I've been having such an excellent time with my IC Boomerang, a bigger heavier beast with more loading (23oz/sqft compared to 20 for the Wot 4) so good penetration and stability in a blow, fine on an OS 46 FX despite pulling only 135W/lb - all of which meant that I've been flying in a much more confident way which I've never enjoyed with the electric Wot 4! So I'm now wondering what the Wot4 would be like with a SC40 in it (projected peak power of 165W/lb)?

I know I'm swimming against the shoal here (everyone is busy converting IC to electric!) but am I being unrealistic to expect the way the Wot 4 flies to change in any way just because of a change in engine type?

Or just accept that the Wot 4 isn't the right hack for my flying style and location...?

Jon

[Kim Taylor]

Jon

Are the numbers which you quoted above actual measured figures, using your own battery and prop, or just a number derived from the max published wattage of the motors.

The reason I ask is that at 135W/lb, I'd have thought that the Wot4 would be adequately powered for normal (not 3d) aerobatics. My own (now deceased) Wot4 flew more than adequately on around 650W (measured).

Having said that, if I build another, I would use a 4250 size motor, propped to 650 - 700W which I know from experience would give me unlimited vertical performance (admittedly at the expense of a bit of top end speed).

You can change the feel of the model by changing the prop, either up in dia down in pitch for static thrust, or t'other way around for more speed but maybe slower acceleration. I think that the beauty of the Wot4 is that it can be all things to all people IF you power / prop it right.

Others may of course feel differently

Kim

[Martin Arnold 1]

The best thing I did to my electric Wot 4 was to install a Saito 56 Four stroke in it, so much more feel to it.... IMHO

[conrad taggart]

Posted by Martin Arnold 1 on 22/10/2020 21:02:41:

The best thing I did to my electric Wot 4 was to install a Saito 56 Four stroke in it, so much more feel to it.... IMHO

Was that the ARTF Wot4 version - have one and just mulling over which engine to fit ?

Thanks

Conrad

[Jonathan M]

Good question Kim. The actual draw for the bigger 4250 motor with a 4s LiPo was originally measured with the watt-meter, and recalculating the results now I realise the figs I quoted above were theoretical and therefore excessive, the actual figs are:

14x7 prop, max static draw 54A, @ 16.8v (full charge) = 907W, @ 5.38lbs AUW = 169W/lb

13x8 prop, maxed static at 50A, @ 16.8v (full charge) = 840W @ 5.38lbs AUW = 156W/lb

I'm currently using the smaller coarser pitch prop (which would possibly explain the hideous whine I often get when opening up to full throttle - as the prop cavitates?) so one option would be to try the bigger finer pitched one, and/or other variations.

I never measured the actual draw when I had the smaller motor fitted, but let's roughly assume that it works out at no more than say 130W/lb. To be fair that was fine in relatively calm weather and pulled the Wot 4 though all manner of normal aeros. But my particular problem is that our site suffers from an exposed hill-top location with slope lift/sink on 2-3 sides plus major turbulence from the non-slope directions in anything above 12mph - when the Wot 4 really struggled to penetrate without the extra power.

Being honest though, I don't get any real enjoyment out of it or make any satisfactory progress with aeros when the breeze is up whichever motor I'm using - the small one doesn't have enough poke, the big one overwhelms me at full chat, and the model still rocks around and/or shoots up/down like a paper bag in the messy air.

Perhaps the answer is simply that - for me, at our particular site - its more of a model to fly only in fair weather...?

Might still try the SC 40 though. The IC accessory pack is only £15 and while it won't change the basic characteristics of the model, it might - as per Martin's experience with his Saito 56FS - animate it differently...?

[Kim Taylor]

My one had an E Max 4020/09 (50mm can dia, so similar to current (sorry)4 Max recommendation). The kV was iirc 470 and using a 6s LiPo I found that a 13x6.5e prop was the sweet spot for me. It was way smaller than the motor was capable of turning, but for me it was ideal in the Wot4.

I originally used the motor in a Wot4 XL and using a 15x8e prop it was producing around 1400W, so , as I said, way below potential but it didn't matter, it was 'free' as I already had it when building the smaller model.

Interestingly, when trying to replicate the power train for use in the Wot4's replacement - a Seagull PC-9 - I used a 500kV 4250 motor on 6s but it wouldn't turn the 13x6.5e prop as fast as the larger, but lower kV motor as the watts were down. I settled on a 13x8e for that one which despite my best efforts, is still flying.

I also fly from an 'interesting' field (on the South Downs near Brighton) which suffers from turbulence from the surrounding hills, etc. unless the wind is directly up or down the strip, which of course it rarely is. I find that the PC-9 is easier to fly in such conditions than the Wot4 was, although if asked to quantify that statement I would struggle to explain - it just feels nicer!!

Kim

[Jonathan M]

Posted by Kim Taylor on 22/10/2020 22:35:32:

I also fly from an 'interesting' field (on the South Downs near Brighton) which suffers from turbulence from the surrounding hills, etc. unless the wind is directly up or down the strip, which of course it rarely is. I find that the PC-9 is easier to fly in such conditions than the Wot4 was, although if asked to quantify that statement I would struggle to explain - it just feels nicer!!

Kim

That's what makes this such a fascinating hobby - so many theoretical factors to gradually understand, let alone the technical and craft skills to learn and flying skills to gain, and then it just comes down to "feeling nicer"!

[Martin Arnold 1]

Posted by conrad taggart on 22/10/2020 21:25:14:

Posted by Martin Arnold 1 on 22/10/2020 21:02:41:

The best thing I did to my electric Wot 4 was to install a Saito 56 Four stroke in it, so much more feel to it.... IMHO

Was that the ARTF Wot4 version - have one and just mulling over which engine to fit ?

Thanks

Conrad

My Wot 4 is a kit built MK2 classic that I originally set up many years ago before lipo batteries were about, it ran on 21 sub c cells !! With an Astro Cobalt 40 motor at about 750 watts. It was very much like trying to fly a Wot 4 with a house brick on board !!

With regard to IC, a couple of my club mates have the Wot 4 ARTF with Saito 56's in them and they are an excellent combination also.

Quite a number of our club are into converting electric models to IC (particularly four strokes), another popular one is the Wot 4-E wood (that's the 80% size one) that goes very well with something like an OS 40 Surpass installed.

[Jonathan M]

I've gone and done it now! Just ordered the IC pack, will fit the NIB SC40 and see whether - or how - it transforms it for me.

Jon

PS When I asked my mate Andy for his view, he replied - "Having considered the matter at length (at least 3 minutes), my view is this: you like engines, and you've never been completely happy with an electric Wot 4. I've flown a Wot 4 and even with a low power 35/40, it's quite nice. So if I were you I'd go for it. Don't forget to fuel proof everywhere." So I had to do it!