Acro Wot Laser

[Chris Walby]

Following the demise of my trusty BH Speed Air (my fault) the search for a replacement airframe for my Laser 70 commenced.

Suggestion of a Acro Wot mk2 ARTF seemed to tick all the boxes and hence a call to Inwoods secured a "to be collected" note.

The rational is something good in less than perfect conditions, aerobatic and low cost.

Should end up looking a bit like this, although I am sure there will be a few snags on the build path!

First question to all owners of acro wot mk2 ic ...any know issues?

[Keith Berriman]

Hi a fellow flyer using an Irvine 53 and stunting around the sky found he needed to add a ply plate to each side of the fusalage to to touch the former of the tank bay and follow part of the curve of the wing seating as it showed signs of cracking in this area. I did mine as a matter of safety

[Bruce Collinson]

Mine's electric but the i/c ones at the club all appear to have had the same issue as mine; the u/c plate isn't strong enough. If I built (OK assembled) one for i/c I'd start by rebuilding the area from the firewall back to the l/e and putting it back a good bit stronger, then with nylon u/c bolts. Presumably the mod above could be done simultaneously.

There's a small patch of yellow film in the box; I recall it's Oralcover so easy to match up.

BTC

[Chris Walby]

Thanks guys, I'll look to incorporate the mods suggested.

I thought the wing to fuselage tang seems a bit lame and sort of remember someone at the club having issues following lots of dis and reassembly he fitted a couple of dowels.

I was thinking of transporting mine complete to save the faff of fitting the wings so will need to consider access to the RX battery although I have a couple of options depending on initial C of G.

Any idea of AUW for the ic powered versions?

[Richard Wills 2]

Chris, had one of these for 2 years now with an OS 55 AX up front. 1100 life pack next to the tank no lead required. Been thrashed to within an inch of it's life since day one, no mods all standard fittings used, it has been absolutely perfect one of my favorite models normally always in the van if I go out.

[jeff2wings]

Acro Wot+Laser 70= well,mine was,just slosh poly/epoxy resin in the tank bay .Here are a few pics of my install

hope that helps !

[Chris Walby]

Jeff,

Very nice job of the carb scoop, how did you get the matching finish?

What stops the tank sliding back and is it in the original position (height wise)?

And lastly where did you mount your tank vent?

Cheers

[jeff2wings]

Not in the picture, the tank was held in place by elastic bands,I glued blocks with hooks each side,think I may have lowered the tank 1/2" ?The scoop was epoxy coated +paint and the vent......

[Chris Walby]

Thanks Jeff and lastly a master class on the cowl very impressive! I think mine will be a bit more oval

Lots done at the weekend so in summary

• Canopy, ailerons and wings glued together with no issues
• Aileron servos installed and control horns fitted...no doubt there will be a comment about the use of plastic clevis's
• U/C looks the same as the wots wot.. expect a springy landing if its not quite right
• Tail wheel seems quite nice
• Cyano the horizontal stabiliser (seems a bit wobbly to me compared with epoxy, so epoxied the vertical fin in and stiffened both up
• Elevator and rudder fitted with control horns
• Extra ply on the fuselage sides as per recommendation + fuel proofed tank bay
• Fitted the servos..oops wrong order!
• What a laugh first getting the elevator rod in and then the closed loop for the rudder
• All connected up and then messing around with the tank
• Fitted the engine using supplied mounts and fixings – looks like the prop is too far to starboard, I’ll leave as is and adjust the cowl to suit and see how it flies
• Throttle linkage redirected, external switch, BEC and RX battery fitted – might go for RX battery in the tank bay if I can sort access out access (yes I know the battery bay (electric versions) cut out is available), more on that later
• Install fuel tank fitted
• Prop fitted and C of G, close but needed 50g up front to get it spot on (without the cowl)
• Control throws, fail safe and build checks completed

Off to the field for range check and engine run test/setting up – only minor issue was the tank vent being installed upside down, but soon corrected.

So still the cowl to do although I think I’ll maiden it without it and then fit it. That way I can see if the C of G need adjusting and it the 50g of lead is better than a brass spinner nut (not prop nut – club requirement to have them double nutted).

[Chris Walby]

Jeff, I have put a 13x6 APC on it, but was just wondering what you have on yours and was it noise tested?

Cheers

[Rich too]

I very nice combo, and refreshing change to all the leccy builds

That's lovely work Jeff.

[jeff2wings]

Chris,same prop and passed noise test but I have a different exhaust setup to you,btw I had a flat Rx pack under the tank and no lead up front.

[Chris Walby]

Rich, the idea is to promote (to those that don't have the experience) that there are easy routes into IC flying without the need to spend hours on the building board or spent trying lengthy periods trying to get the thing to run correctly. Basically a good all rounder and winter hack.

Jeff, No where near as good as yours, but functional

Busy day, Shuttleworth then noise test and maiden if I can....

[Jon H]

i wanted to go to shuttleworth but the weather makes it not worth the drive for me

[Chris Walby]

Time for an update, well I got around to breaking out the battery door and made a couple of pins/catch for it. Now the RX battery sits under the tank so easier to replace rather than cable tying it next to the RX. More on this later

I have been having a few issues with the engine running a bit odd (like randomly stopping at tick over - most likely a result of be burying the Speed Air at near full speed - testament nothing appeared damaged on the engine).

With a nice Saturday up at the club it was time take the cowl off and do a proper job of setting the engine up. The result was much improved (it was running too rich at the bottom end, my gaff) and discussion ensued with Dave (one of our instructors) regarding the 30g of lead on the front of the engine. Decision was to remove it and it balanced about 3mm further back than previous (as the RX battery had moved forwards).

Next flight and it was even better tracking, landing seemed easier and on high rates the roll rate is truly like a corkscrew!

Only one thing to do, refuel and ask Dave if he would like a go! Well needless to say we got a cracking display of precision aerobatics only spoiled by the low vertical dead stick.

Due to the noise yesterday I did another tune today and it was on the lean side so would this have been the cause? Once retuned I gave it my best and couldn't get it to die.

[David Davis]

Any views on mounting a Laser 80 to this model?

[Chris Walby]

Hi, Best ask Jon!

The 80 is 110g heavier than the 70 and mine has no lead (but as much forward as possible).

Having said that mine only weighs 2.5Kg and lands very slowly now I have upped the elevator throw and cut back the expo a bit.

If you only have a 80 and no home for it, want a winter hack, nice aerobatic model and something super fun then go for it !!

I know nothing about design, but judge a good model as one that that can be flown tame to bonkers and has no vices (this ticks all of the boxes).

PS Above my standard, but Dave seemed to enjoy flat spinning it and some very low big loops (starting less than 10ft). I have a spare RX with giro and sort of considered putting it in for the really windy days, but if I drop the rates and don't land it directly cross wind it might not be worth the effort...time and weather will tell.

[Jon H]

Posted by David Davis on 22/10/2018 06:29:41:

Any views on mounting a Laser 80 to this model?

wont fit

This is a different design to the old kit version and the engine bay/cowl is much shorter. Unless you want to get creative its not very easy to get it in.

All that said, the 70 offers plenty of power so the 80 is not really needed

[David Davis]

Thanks Jon.

I'll put the 80 into my BE2e when that finally gets built, and I'll put a 70 into the Acrowot. I have three 70s to chose from, two of them brand new and un-run!

[David Davis]

Having wrecked the Fun-Fly because the negative cable from the battery failed last Sunday, the obvious replacement is the ARTF Acro Wot kit I've had lying about for a couple of years. As I have three Laser 70s sleeping in their boxes, and as I have been boring my French clubmates about how good Lasers are, it's about time I put my money where my mouth is and showed them one in action.

However, many assemblers have reinforced the fuselage from the firewall back to second former, just in front of the servos. The fuselage is made out of fretted-out plywood which is covered in balsa wood sheet. So a few questions for you.

1. When reinforcing the sides between the two formers have you simply glued plywood to the fretted out ply fuselage sides or have you filled the recesses first? If so, presumably you've used balsa.
2. I can see no way of reinforcing the fuselage sides of the tank bay and the undercarriage mounting without cutting away the lower sheeting, replacing it and re-covering it. Is this what we do?
3. Would fibre glass and epoxy be just as effective? If so would you recommend epoxy resin or could I get away with PVA?

Picture of my virgin Acro Wot fuselage below to assist you.

[Bruce Collinson]

David,

You either do it now by disassembling it in controlled circumstances or later when the almost inevitable ensues. I have only experienced the latter but as I recall posting above, next time I’ll retaliate first.

i suspect there’s little to be gained trying to fill in the cutouts but lots of epoxy in the joints might help, then ply, and I would glass and epoxy it too. Also triangular stock in the joints.

Jon H posted a pic which I tripped over earlier, showing a sacrificial u/c plate with nylon bolts instead of the design steel bolts. That prompted a reply that it would lead to collateral damage to the wing or tail as the cart clouts them on the way past; struck me I’d rather patch yellow Oralcover than rebuild the bottom of the fus. Also mitigates the problem of getting the nylon stubs out of the T-nuts if they shear flush.

great all rounder, love mine to bits.

BTC

[Chris Walby]

I just added some balsa sheet to the sides of the fuselage where the wing rests to add a little strength and epoxy fuel proofing that was all.

IMHO The 70 really suits the Acrowot if you keep it light. Okay its a little quick to land when its dead still, but how often is that?

I use mine in all weather (except when no one else will fly) and that's because I have something else far more expendable, but the key aspect for me is its light but still seems very stable if windy.

If you start adding weight it will land faster and you risk doing more damage. Its like putting a 80 in it, okay it will pull unlimited vertical and the additional stress of throwing it about will cause other issues.

I like the idea of the Nylon U/C screws, but other than that mine is standard and AUW is 2.9 kg

Good luck and post how you get on with your build.

[Chris Walby]

I just added some balsa sheet to the sides of the fuselage where the wing rests to add a little strength and epoxy fuel proofing that was all.

IMHO The 70 really suits the Acrowot if you keep it light. Okay its a little quick to land when its dead still, but how often is that?

I use mine in all weather (except when no one else will fly) and that's because I have something else far more expendable, but the key aspect for me is its light but still seems very stable if windy.

If you start adding weight it will land faster and you risk doing more damage. Its like putting a 80 in it, okay it will pull unlimited vertical and the additional stress of throwing it about will cause other issues.

I like the idea of the Nylon U/C screws, but other than that mine is standard and AUW is 2.9 kg

Good luck and post how you get on with your build.

[Tim Flyer]

I’m well into my Acrowot assembly with a Laser 70 . I have also added a side scoop/cutout for carburettor clearance. I’m making a ‘custom’ out the bottom exhaust too as clearance against firewall is insufficient on my version and I’m not going to cut the firewall . I added interior balsa fillets. In the tank bay and firewall I’m adding fibreglass and epoxy the rest of the inside will just have a light coat of epoxy as I usually do on my models . Will be good to compare our set ups . I will post some photos later. This should certainly build a fair bit lighter than my Acrowot kit version so will be interesting to compare how the two fly.

[Chris Walby]

Hi Tim,

I don't quite understand why your exhaust is too tight to the bulkhead when I managed to get mine in ok?

Although I am using one of those rubber angled deflectors it does point nicely through the cowl.

I fuel proofed and add a little balsa, but nothing else.

PS the photo is pre-inlet scoop.