Acro Wot Kit

[Michael Little]

Hi all,

Im currently building an Acro wot, (My first build & IC Engine plane)

I have decided on an OS65AX & 14x6 prop with a 10 oz fuel tank (I hope big enough for decent flying time?), What spinner size are people using?

Also does this need standard size servos?

Sorry for the basic questions but its my first build and non foam rc plane!

And as i understand i will need to epoxy the fibreglass sheet to join the wings together, then just film over the rest of the plane?

Thanks

Mike

[ken anderson.]

hello mike and welcome from me.fit a spinner to suit the dia of the front cowling(off the top of my head 1.1/2--2".use a wing joining kit which will include a bandage for the joint.film will be fine for the model,use standard size servos(Futaba 148's-cheap and reliable)before you fit the top front deck to the model use any spare wing joining tape and some resin(do both at the same time-wing and undercarriage mounting area) with some reinforcement ready for some heavy landings..... hope that's clear for you.... if not ask as many questions as you want.

ken Anderson...ne...1 A/Wot kit dept.

[Keith Berriman]

Just a thought. A 65 ax for a new flyer may be on the powerful side do you have anything smaller ?

[Michael Little]

Posted by ken anderson. on 03/07/2017 15:31:32:

hello mike and welcome from me.fit a spinner to suit the dia of the front cowling(off the top of my head 1.1/2--2".use a wing joining kit which will include a bandage for the joint.film will be fine for the model,use standard size servos(Futaba 148's-cheap and reliable)before you fit the top front deck to the model use any spare wing joining tape and some resin(do both at the same time-wing and undercarriage mounting area) with some reinforcement ready for some heavy landings..... hope that's clear for you.... if not ask as many questions as you want.

ken Anderson...ne...1 A/Wot kit dept.

Thanks very much for the advise!

I think i may be too late by the sounds of it depending on what you mean by top deck, as I've completed most of the fuselage. Ill take some pictures when i get home so you know where i am in the build process. & Thank you i really appreciate your help I'm sure ill have many more questions!

Mike

[Michael Little]

Posted by RC Plane Flyer on 03/07/2017 15:38:26:

Just a thought. A 65 ax for a new flyer may be on the powerful side do you have anything smaller ?

No mate I've pulled the trigger on this already!

[ken anderson.]

ok mike-i'm talking about the area inside of the tank bay(the floor) the part where you drill the holes and fit the captive nuts for the undercarriage, this plate takes most of the forces when you land and if you come in too heavy it pulls out with the undercarriage still attached to it...so to give it a bit of extra strength it can be beefed up with a bit of bandage and resin...another fix is to use plastic/nylon bolts in place of the metal one's - they will snap instead of the plate getting pulled out...... not the end of the world if you cant get to it....

ken Anderson...ne..1 ....beefed up dept.

[Jon Laughton]

Hi Mike

I agree with Ken's suggestion of reinforcing the inside of the fuel tank bay and the firewall. Yes the model accepts standard servos but I think it would be way overpowered with a 65ax - in my model ten years ago I had a 55ax and that was more than enough. The bigger engine will make the model heavier and therefore it will have a faster landing speed/higher stall speed.

It's a great model and I am sure you will enjoy it!

Jon

[TIM Shaw]

I Love the Acrowot and have my sixth kit in the garage ready to start.

Definitely agree on reinforcing the tank bay floor / U/C mount area. Even if you have completed your fuz build you can still get at the area through the tank access in the former - bit fiddly, but perfectly doable.

If you're using that size motor I hope you followed the advice and moved the firewall (F1?) back a tad........

I've used a variety of engines over my association with this plane. First one had a Magnum 45 Pro in it, flew fine but really needed a pipe to perform.

I later tried an OS 70 Surpass, 4 stroke, but I had that one painted by a mate who gets a great finish. I didn't appreciate, up to that point, just how heavy paint can be and this, coupled with the weight of the engine, made it my least successful one.

Favoured power plant for me is a 61 2 stroke, I've used both OS 61 SX and Thunder Tiger Pro 61s with equal success. I'm sure a 55 AX would be fine, but I'd have no concerns about the 65 either - I think is actually lighter than the "smaller" (60 size)  engines, as they share the same mounts but there is a bigger hole in the larger capacity, and of course, you don't need to use full throttle all the time..........

I recall Chris Foss suggests putting a spar in the tailplane of the Wot 4 if you are fitting a big engine, but I don't know of any AcroWot tailplane failures myself.

As far as covering, I'd be happy with filming the wings, but I prefer either glass cloth or nylon for the fuz, as they do add a bit of strength you don't get with film.

Good luck with it, it's a great design and a super sport model.

Edited By TIM Shaw on 04/07/2017 10:20:31

[Cuban8]

My only bit of advice would be that seeing as this is your first non-foamy model and it's likely to have considerably more performance and weight than you might have been used to, I'd have an experienced flyer take it up to trim it out and allow you settle in with it at height with lower power settings. Give yourself ten minutes with it though and you'll be away. Explore it's flight envelope over several flights without rushing things and you'll have a superb model that will give you plenty of fun.

[TIM Shaw]

Hello Again Mike

Cuban 8 is spot on there- I credit the Acrowot with really teaching me to fly - sure, I'd become competent on a Tyro Major, Student and Wot 4, but I only really got it when I did exactly as he describes.

One other tip I forgot about earlier. The Acrowot has only a 1/8" LE IIRC, and the wing dowels tend to work loose in time, particularly if flown strenuously (and that is what it is for......)

So now, whenever I build a foam wing in fact, I epoxy the cores together, and line out the servo box, but then, before I apply the glass bandage, I sink a balsa sub-spar, maybe 1/8" or 3/16" thick and about 3" long right into the wing from the top about 2" back from the leading edge. It doesn't matter if you slice right right through the wing and slot it in full depth, the idea is to tie the top and bottom skins to the rear of the wing dowels.

Once set and sanded to fit I apply the wing bandage.

Then when I fit the dowels I make sure I drill through the LE and the Sub spar, and I haven't had a dowel come loose since. If you are really fussy, some people drill the LE and spar out slightly over size and fit tubes, so dowels can be replaced easily if necessary.

On the subject of easy repairs I am not a supporter of nylon U/C bolts - sure, they may save you ripping the tank bay floor out, but they may also fail when the structure otherwise would not have done, which usually results in a more awkward repair where the wheels have gone through the bottom of the wing.

Make sure you add plenty of shape and lightness by not skimping on the shaping of the fuz too - the Acrowot is not such a job in this area of some of the old pattern ships, but it's still an area where a bit of weight can be saved, and lighter is better!

Edited By TIM Shaw on 04/07/2017 12:27:33

[Richard Wood]

Good idea about the wing dowel reinforcement there Tim. Polystyrene foam wing cores
never give great confidence in being the ideal anchor for them, liberal use of epoxy or not.

Many people do tend to use metal u/c mounting bolts & an unfortunate sight after a heavy
landing is often a ripped out lower front fuselage with the u/c still firmly bolted to the
broken off ply mount.
Never personally had a failing nylon bolt in all but the heaviest 'arrival', which is why we use them.

Shaping a balsa fuse with razor plane & progressively finer grades of glasspaper is one
of the most enjoyable parts of building.

 

 

Edited By Richard Wood on 05/07/2017 11:47:36

[Keith Berriman]

Galaxy Models used the ply insert method in the wings on two models I built

[TIM Shaw]

Yep - watching an aeroplane shape emerge from a log is indeed one of the most satisfying bits, although it does tend to make a bit of a mess..Nearly got to that stage with my PB Bullet myself. I guess nylon v metal U/C bolts is a bit like whether to steer your noseleg or not - Marmite issues you have one view or the other on.

Never built one of Galaxy's offerings but I would have thought that ply would be a bit OTT, scrap balsa works just fine for me.

[Michael Little]

Hi all, sorry for the late reply! Just a quick update. So I've used fibre cloth and e-poxy to cover the fuselage. My next task is to try and reinforce the undercarriage. Where i orderd the OS65 they didn't have stock so i have canceled the order as per suggestions and i will order the 55 later on. Also on servos are the Futaba 148s plenty adequate for this plane then? 3.0kg and 0.22 seconds?

Since i have epode the plane is it easier to paint it now? if so how would i get rid of the gaps where the hinges are on the control surfaces?

And thanks For the Suggestions also Tim ill reinforce the dowels in the wings when i get to it!

[ken anderson.]

Michael---- 148's will do nicely ...one time they were the staple diet of most sports models.if the gap is large and the control surfaces are hinged/mounted use some good quality clear tape(deflect the surfaces and fit the tape to the top only)if its a small gap-forget about it...its only a sports model at the end of the day....I've seen allsorts of variations over the years of the Wot models...............

ken Anderson...ne....1.... variation dept.

[Michael Little]

Ok thanks Ken really appreciate it! i have just ordered the servos so should get them Tuesday, the fuel tank came Friday as well so ill look at that later! Cheers ill try and keep the gaps minimal then if i can to save adding the tape if it won't make that much difference anyway!

Thanks,

Mike

[Michael Little]

Heres the Acro Wot so far!Does anyone have any photos inside of the servos and the tail section where the rod/wires get to the rudder/elevator that i can see please?

Mike

[David Davis]

One aspect of the Acro Wot which has not been raised in this thread is its ability to fly slowly. I've had two of these, both of them bought second hand. I fitted several engines to them but my favourite was the OS 61SF. They flew beautifully but they both met their end through me landing them too quickly on a grass strip. In both cases, the undercarriage took out the F2 former, then the wings came off and took the servo mounting plate with it. Quite extensive repairs were required! I gave the silver one to a friend who has never repaired it, but then again, he has one in flying condition.

Rest assured they will fly very slowly on landing approach and loosing the undercarriage was entirely my fault. I must buy another kit next time I'm back in England.

Pictures of my two examples below.

[Glenn Philbrick]

These photos show a mod I have been doing to all my Acro wots and other similar models, most of our club also do this now. By replacing the the blind nuts with 6mm ones and using plastic bolts I have not torn out the bottom of this acro wot and fly it most weeks. The ply plate makes sure that when you break the bolts that there is enough bolt to be able to get out easily. I buy the bolts in bulk but it is better than trying to glue the plate back on when fuel soaked.

[edgar]

Here are some photos of my much flown, much crashed and much re-built version. It came to me second hand, I think its about 20 years old, it has a single central(ish) servo in the wing and off-set aileron torque rods (to match the off-set wings and tail), hence the offset cut out in the wing retention plate. I don't know how much help this is, mine has snakes instead of push rods, these were installed by a previous owner, I don't know why, I don't think there is anything wrong with push rods in this model. It still flies well despite its extra weight and slightly asymmetric build.

[TIM Shaw]

Hi Michael

It all looks pretty good to me - satisfying to create something isn't it?

I agree, 148s will be fine.

I tend to paint my models before I hinge the surfaces, I dry fit mylar hinges temporarily during the build, remove them again prior to covering, and only epoxy them inn after all covering, painting etc has been completed.

Then I pin them and I don't try and hide the pins - it gives me a certain amount of reassurance to be able to see them.

If you have already glued your hinges in then i guess painting will be a bit more difficult - is this what you mean by "gaps where the hinges are?"

David is quite right about the slow speed flight capabilitie, the Acrowot will happily fly backwards in a good blow, will land slowly and is very reluctant to drop a wing - although it will if you really provoke it.

Glenns idea is neat too, as anyone who has laboured with a heated screwdriver trying to extract the broken bit of a nylon bolt out of the nut will agree, and he is right about gluing back oil - soaked wood, That particular problem has caused me to give away at least three of my well-flown ( perhaps that should have been "much flown" ones to club mates after i got fed up of trying to make a success of it.

[Michael Little]

Hi all, Thank you very much for all your photos its made it a lot more clear to me viewing them now! i noticed Edgar the rudder isn't 2 wire lines to either side of the rudder (I'm sorry i don't know the technical term!) Is this common not to get with the wire system that is in the instructions?

Also im not clear what clip is needed to insert in the rudder for the spring to connect the tail wheel, is this something someone could link please?

And Glenns thats definitely worth thinking about, whats the purpose of the black plate may i ask that the undercarriage sits on?

Yes Tim its very satisfying! i have loved making it even though i didn't realise what a Kit was i thought i was basically what an ARTF is as i got it for £60 off eBay without looking into it but I've very glad i have done it so far!

Ive got all the Servos and picked myself up a AX55 today also from LMA Cosford show, looks like a really nice engine i want to hear her running now!

[TIM Shaw]

Hi Michael

The rudder control system you refer to is called a closed loop. Its just 2 wires, one from each side of the servo connected to each side of the rudder horn, and all the kits I have built have the necessary bits included.

As for the tail wheel, I think the original idea is to stick a pin into the base of the rudder and use a small rubber band to connect that to the arm on the tail wheel .

But I have found the ground handling id fine if you just fit a skid, TBH, and its much simpler.

There again, I don't do the whole taxying thing - I just head into wind, open it up and leap into the air.

HTH

[edgar]

Hi Micheal, I now remember that the original kit uses a closed loop (two wire lines) for rudder, mine has been changed. It is quite common for kits to require additional hardware like this but i don't know what is supplied in the the Acrowot kit, because mine was second-hand. There are various tailwheel designs available with different methods for connecting the rudder to the tailwheel, again I think the original kit just has a simple tailskid.

[Michael Little]

Ok thanks ill remember that! i guess ill stick to the closed loop then for now as i have all the correct items for that

oh ok it doesn't seem like the original would be that good but ill have to see it working before i comment i suppose!

Also does the wing need a spar to connect the two before sticking them together or is it literally just the epoxy holding the two together?

Thanks again for all your help it has been a great help to my build so far!!!

Mike