Ripmax ARTF Wots Wot

[Paul Marsh]

I've a Thunder Tiger 91 four stroke in mine.

[Phil 9]

Posted by Jim Purcha on 15/04/2017 22:30:14:

Thanks, whatever the material is, the girls in the shop do a btter covering job than me.

What's everyone using for an engine? This is my first biplane.The look seems to cryout 4 stroke.

The snow and ice have left the field, and flying is being here in Winnipeg, Canada. I have to finish by Hawk for next weekends "Show and Tell" at spring club meeting.

Jim

Edited By Jim Purcha on 15/04/2017 22:30:55

Edited By Jim Purcha on 15/04/2017 22:32:59

it cries out for a Laser

[Bob Cotsford]

Laser 80 is on it's way for mine. I'll be interested to see what options there are for the exhaust to exit the cowl with a minimum of cutting.

[Hangar 9 nut]

Saito 82 in mine flies great !

[Bob Cotsford]

Looking through the instructions (I know it's not done but it's a damp Bank Holiday) and I see the spinner to bulkhead distance is shown as 127mm. The Laser web site shows the length of the 80 as 135mm, so I need to bring the cowl forward around 1cm to avoid an ugly gap between it and the spinner yet still allow the carb room to breath. How far does the cowl go over the fuselage using the stated 127mm? I'll add some hardwood mounting blocks to the front of the bulkhead for the cowl to screw onto, assuming that the cowl will still overlap the fuselage!

[Concorde Speedbird]

Fits okay. Mine has a cowl-spinner gap, but you could mitigate that with the method you described. My one is currently serving as an engine test bed for a Saito 82 for another aeroplane, should be interesting to compare it to the Laser.

[Bob Cotsford]

Thanks for putting up the picture CS. It looks to be about 1cm overlap in your picture. If I wasn't so lazy I'd go and measure the cowl

[Bob Cotsford]

The Laser 80 arrived this morning (thanks Jon) so it would have been rude not to offer it up. Being a cheapskate rather than buying the IC additional parts kit I used what I had to hand. I found a set of mounts that fitted along with a 12oz tank - more is better isn't it? With a couple of areas of the side sanded back a shade the existing front mounting bolt holes line up and I should end up with a 5mm gap behind the spinner and 5mm clearance for the carb and exhaust. A smear of epoxy over the grooves that I've put in the side/firewall and jobs a good'un

[Jon H]

No worries Bob. 12oz should keep you flying for at good 20 minutes. I use 12oz on the 155 and still have 10 min flights

For your cowl, can you not shuffle it forward a few mm to close the spinner gap? That said 5mm is not exactly a gaping hole is it.

[Phil 9]

Is that side monted bob?

[Bob Cotsford]

Jon - from measuring the cowl it looks as though there is next to no overlap on the fuselage. I can live with 5mm or so.

Phil - yes, it's side mounted using the pre-drilled bulkhead holes and some ex-Acrowot mounts acquired from my nephew (he's re-engined his AW with one of my OS SF61s after his SC46 sheared it's crankpin, that will be interesting).

I had a good look at the wings and tail this morning - I've never seen such wrinkled covering!  It's not just gone slack as per most ARTFs, it's wrinkled like a prune. 

Edited By Bob Cotsford on 20/04/2017 12:20:10

[Bob Cotsford]

It flies - but it needs some lead in the left wing to balance it up. One deadstick on the second take-off, but I think it was because I hadn't let the engine warm up enough before take-off. Deadstick at 20' just as it crossed the hedge boundary, luckily the field beyond has just been seeded so was relatively smooth for a blind landing with no damage.

The Laser 80 will lift it off at half throttle with ease, vertical looks to be unlimited but with a 14*6 it doesn't try to rip the wings off on the level.

Now I can fit the cowl as the Laser idle mix is perfect as it came out of the box

[Tim Flyer]

Interesting fun model Bob I thought the 80 might go well , a good little brother for your Wots Wot XL. I will be interested to see how much lateral balance you need as my Wot 4 needed a fair bit tooI buried an old broken steel 4s exhaust adaptor in the wing😉. . The laser 80 is great in my Wot 4 . I did have to lean my idle in on both my laser 80s as they were running in so it might be worth a double check? In my Wot 4 I stuck with a 13x7 prop which seems unlimited but I think a 14 x 6 might be similar but with a bit less top speed...pleased I have air brakes...they work well!

[Bob Cotsford]

Hi Timothy, unfortunately the XLs will have to go once I steel myself to advertise them so this one will be a replacement at a size that I can handle, also it will fit in the back of the car in one piece. Yesterday I made a couple of wedges to go under the engine mounts, reducing the side thrust by half and adding a degree or so of down thrust.

Because the tank cant go level with the carb (the centre cabane mounting gets in the way) the engine's having to suck a bit harder to get the fuel hence the 'rich' setting out of the box is pretty close for the setup. If I wasn't lazy I'd have mounted the engine at 135 degrees to get the carb level with the tank. Luckily the engine doesn't care and seems happy enough inverted and through outside loops as it is.

I'll reckon it will need 20-30 gms in the wingtip to balance, with luck I will be able to drop it through from the root rib cutouts and it will get all the way to the tip so I won't need to take a knife to the wingtip. I'll get the wing off and check later, apparently my priority this morning is to go shopping for cat food.

[Bob Cotsford]

25 gms of lead plus a good goop of epoxy in the left upper wingtip has the wings level when balanced on the top wing join. I've also swapped the aluminium spinner for a plastic one to lose some weight from the nose. It would probably benefit from some lead in the tail but it's close enough for now.

[Jon H]

Low is better than high when it comes to tanks Bob so i would not be concerned.

As for the deadstick, you must have upset it somehow

[Bob Cotsford]

Posted by Jon Harper - Laser Engines on 04/05/2017 16:20:52:

Low is better than high when it comes to tanks Bob so i would not be concerned.

As for the deadstick, you must have upset it somehow

'fraid so Jon, for the second flight as soon as the engine fired up a kindly club member offered to carry the model to the strip for me and the engine didn't get time to warm up properly. Mea culpa .

I reckon that the 12 oz tank is good for at least 20 minutes of mixed running, that's comfortably exceeding my attention span

[Tim Flyer]

Good to hear Bob . You will get at least 20 minutes in that tank. I use the same size on my Laser 80s and it provides a long flight....that's useful as my young son often takes over for a while on each flight too . I will have to laterally balance my XL too ....still haven't done it yet despite side mounted engine😳.I think that little Wots Wot is a great plane. Lots of the guys fly them at our club and they are nice even with some of their slightly "ropey" old two strokes 😊 . With the Laser 80 it will be like an everyday Bentley Turbo😊. The big Wots Wot is a bit of a faff sometimes I agree as its big and needs a lot more shunting around and fiddling on each outing which is a pain when it's cold and windy. That's one if the reasons I too enjoy "80 FS " sized planes as they are at that sweet spot for me of practicality and cost. Even so I still have space in the hangar for a few XLs😉. Happy Flying ...Tim

[Bob Cotsford]

Both XLs are on their ways out of the door . Didn't take long on fb groups! I was getting queries within minutes, it's the power of social media in action

[Neil James]

Finally got mine flying after months of faffing about. There’s some interesting suggestions on this thread which I will take up. First impressions are that it flies great on the recommended motor/battery setup, but assembling it was a pain.

I’ll be replacing the interplane strut bolts with clevis pins and R clips, already found some on eBay to save me having to mess about drilling holes in a 3mm bolt! Secondly the aileron connecting rods aren’t up to much either: the plastic clevis is very poor quality and the bend at the other end is only just long enough for the swing keeper to hold it in position so I’ll be replacing those with new rods with a ball joint on each end.

[Chris Walby]

Neil,

WARNING (as I assume yours is electric).

THERE IS A MAJOR DESIGN FLOOR WITH THE BATTERY TRAY

IMHO the keyhole on the battery tray is the wrong way around...pull hard into vertical, stall turn and you may be met with the battery hanging out of the plane! I got 3/4 around the field and then the lipo departed from the ESC EC5 connector at about 40ft up. Brings a new meaning to dead stick. Lucky to get away with just ripping the wings off the fuselage.

Fix can be battery tray with just a hole or (my option) a button that drops in the keyhole and is held captive by the screw head.

Great model, but pity so little thought was given to the electric conversion. PS the battery cover is pants as well!

I'll post a photo of the "button"

Edited By Chris Walby on 26/09/2017 14:45:25

[Neil James]

Thanks for the warning!

I agree the battery tray could be better secured, I’ve only had a couple of flights but each time I’ve made very sure that the securing bolt was done up tight. It’s a heavy battery to be restrained just by friction though so I’ll be interested to see what you do, I’m certainly keen to improve it. I was think of adding a peg in the fixed plate to mate with a hole in the removable one and this would then take the sliding forces. 

As far as the battery hatch is concerned, it was such a poor fit that I decided not to bother with it!

Edited By Neil James on 26/09/2017 15:44:40

[Chris Walby]

Neil,

I thought long and hard about re-engineering the battery tray a fool proof way of locking it in and in the end came up with this:

Its simple and fool proof and requires no modification to any existing other parts.

Just inset battery,

Drop plug in (photo is with plug upside down).

Inset and lightly tighten screw down

Go have some serious fun! hope this helps

[Neil James]

Thanks Chris, that looks like a simple fix, certainly easier than trying to drill matching holes in things now it’s all glued together!