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Oct 09, 2014, 11:46 AM
Late for work again!
Gary Binnie's Avatar
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Finally got to the model shop to buy some laminating resin and lightweight glass cloth for skinning. Also bought a box of powder free rubber gloves from the chemist, they always look at me strangely when I ask for them!!

The glass cloth reinforcement for the wing centre join is supplied with the kit, I had visions of an ugly bump with all the layers but there's hardly a bump at all in the end, I was probably thinking of when we used actual cloth bandage and PVA glue!

Quite a messy job, it pays to have all tools and materials ready to go, as it was I had to mix a little bit more resin up halfway through (used 50 ml in all).

Pictures show the process though I didn't take any during the job as the camera would have got a bit sticky!

Yesterday I messed about with the cowling and cheek fairings, just opened up some holes and added balsa backing to the cheeks for more gluing area.

GB
Last edited by Gary Binnie; Oct 09, 2014 at 01:47 PM. Reason: Forgot a caption
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Oct 13, 2014, 12:38 PM
Late for work again!
Gary Binnie's Avatar
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A little more progress today.

Drilled the wing dowel holes, has to be done by twisting the drill by hand, slow but you get there in the end! The dowels are pre-cut and in the hardware pack, I made a mistake and cut them from the length of dowel provided for the elevator pushrod.

The ply undercarriage plate needed a chamfer on it to clear the wing, radius sanding on both sides and two 'T' nuts fitting.

Fitted the plate with epoxy and left to set overnight.

I've weighed everything and it comes to 5.5 lb, guessed the weight of the engine and rc equipment and arrived at 8.5 lb. Must have forgotten something as 10.5 lb is normal finished weight, we'll see.

GB
Oct 13, 2014, 01:41 PM
Registered User
Mine was 9lb 3oz with the OS120AX and all gear in it apart from fuel. Add the weight of covering and you'll maybe get up to that weight.
Oct 13, 2014, 06:05 PM
Late for work again!
Gary Binnie's Avatar
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That's quite good, my last one was 10.5 lb but not very well built (second hand).

I'm probably going to glass it all over against Chris's advice which won't help.
Oct 15, 2014, 02:26 PM
Late for work again!
Gary Binnie's Avatar
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Hinges and stuff


Couldn't put it off any longer, had to do the hinges!

Really wasn't keen on using the Mylar strip supplied hinges so the choice was Kavan flat pinned hinges or Robart point hinges.

I find the process of hinge slotting and digging out balsa a bit brutal, Robart hinges are easier to use IMO as it's just a single drill hole for each but they have to be exactly aligned which has caused me problems in the past.

Been borrowing a Robart drill jig from a friend and thought it would be a good idea to get one of my own, 7 is a bargain! I modified it after reading a forum thread, just glued strips of 240 grit on the faces of the steel bars to stop it slipping, works a treat.

Another forum thread showed a tip using hole transfer punches to transfer the hole positions to the control surface which is an excellent idea. Couldn't find anything like that in the UK so I used pointy grub screws and thin nuts, works just the same.

With the hinges drilled the facing strip of the ailerons needed chamfering to allow movement. I had a handy sanding tool that came with a Goldberg Ultimate but it was taking ages, made a bigger version of it which worked very well (still took ages though!!).

Doing much the same to the tailplane at the moment and having fun tapering the elevators from 3/8" to 1/16"!!

GB
Oct 15, 2014, 06:41 PM
Late for work again!
Gary Binnie's Avatar
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Just found some photos of my dead Xtra Wot, I kept the wreckage for a while then sawed it up as it was taking up too much room!
Oct 16, 2014, 12:47 PM
Late for work again!
Gary Binnie's Avatar
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Was dry enough today (but not for long!) to put it all together again in the garden, getting there.

Today's building has been hinging the rudder and lining the aileron servo bays.

Nothing tricky about hinging the rudder apart from the middle hinge goes through the stern post and the fin, I drilled it without the fin and wondered why the hinge wouldn't push in when I put it all together!!.

The instructions say to cut out the aileron servo recesses but they're already done, hoorah! Just need to line them with balsa (not forgetting to open a hole for the servo lead) and sand flush with the wing veneer.

On the first one I was a bit mean on clearance around the servo, I increased it on the second one. Not sure how much vibration gets out here but I like to let the rubber servo grommets damp it out.

They will have hardwood rails fitted for the screws on final assembly.

A related job was fitting the triangle ply reinforcing plates for the control horn (same job was done on the rudder).

GB
Oct 22, 2014, 12:35 PM
Late for work again!
Gary Binnie's Avatar
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This week I have been mainly glassing!

Ailerons and fin are done, not weighed them yet to see what the increase was but I did my best to be economic with the resin.

Have to work quickly with the wing, a large area to get covered before the resin starts to set (I don't thin it on veneer).

A tricky problem is how to hold the wing for glassing, I discovered that I could fit it to the fuselage in the wrong bolt hole (offset to one side) then I realised that I could just clamp the side not being worked on between the foam beds and weight it down with batteries.

Not the best weather for glassing, cold and damp, so once I've got a panel done it comes in the house to harden (more tough stares from 'the management'!!).

GB
Last edited by Gary Binnie; Oct 22, 2014 at 12:50 PM.
Oct 22, 2014, 01:23 PM
Registered User
What prompted you to glass it, and what weight glass are you using? I used Solarfilm (or Solarspan, can't remember which) on mine, and I normally only use glass on models that need the extra strength, or which I want to paint.
Oct 22, 2014, 02:52 PM
Late for work again!
Gary Binnie's Avatar
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Just thoroughly fed up with Solarfilm. it's almost a brilliant product.

Fuel getting under it, even using 'Clearcoat, seams lifting ('Prymol' treated) and bubbling in the sun (especially in the car) which is probably the most annoying problem.

I believe Profilm/Oracover is better but would be quite expensive for a model this size.

My Wots-Wot was glassed all over and spray painted with full-size aircraft primer and two-pack, not the lightest but it flies well. Next year it will be 20 years old.

Deluxe Materials 0.6 oz/24 g/m2 is the cloth that I use with either Z-Poxy or Aerokote resin.

If the wing comes out super heavy I might swap to tissue and dope on the rest of the parts.
Oct 22, 2014, 03:29 PM
Registered User
Ah yes, I'd forgotten about that fuel stuff But I don't seem to get many wrinkles these days.

I was just curious about the weight of cloth, for I'm about to glass the fuselage of a mosquito I'm building. I couldn't make up my mind between 25g or 50g -- I think I'll go for the latter, for the fuselage is planked and then sanded down quite a lot to get it smooth, so the balsa is quite thin now so needs some strength adding.
Oct 22, 2014, 07:33 PM
Late for work again!
Gary Binnie's Avatar
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The majority of the weight increase is from the resin, I mixed about 50 g (2 oz) for each panel (one side, top or bottom) but quite a lot got scraped and blotted off or was left in the mixing tray.

I'm using Z-Poxy's instruction method of paint the surface, lay the cloth and squeegee (the other way is to lay the cloth then push the resin through it). The resin is getting sucked up by the veneer so things are quite dry when the cloth goes on needing more resin over the top.

I don't mind the resin soaking into the veneer as it will toughen it but I might try a sealing coat of dope on the balsa parts and see if that makes a difference. Didn't use dope on the wings because of the small risk of dope getting to the foam and melting it.

Some people swear by 'Poly C' but its water base can wrinkle veneer skins, a mistake that I made once before (wet and dry sandpaper used wet!).
Nov 21, 2014, 03:54 PM
Registered User
Wot would be better gas engine for this: 20 or 30 cc
Nov 22, 2014, 02:39 PM
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Gary Binnie's Avatar
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Was wondering that myself, probably the 30 cc.

Build is still going, just glassing things and waiting for a surge in funds to equip it!
Feb 11, 2015, 10:23 AM
Late for work again!
Gary Binnie's Avatar
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Still going!


Meanwhile, two months later...!

Have not done much building as such, just some glassing of bits and pieces.

I've mainly been biding my time searching for and buying the engine and related parts.

I found a 'new' OS120AX on a well-known auction site and snapped it up (just under half retail price). The owner did say that it had run once on the bench, I had worries about the condition of the crankshaft bearings after reading about this engine so I took the back plate off, sure enough the main bearing was toast.

I completely stripped and rebuilt the engine (everything else was 'as new') and it started first time on the test stand and runs very nicely.

Missing was the 90 degree exhaust adaptor, easily replaced.

I decided to go for OS's dedicated aluminium engine mount which also took a while to find and get hold of (you could buy a small engine for the price of one of these!!). It was NOS from another modeller so the price was much better than retail. It is quite heavy compared to a nylon mount, if the model ends up nose heavy I will have a rethink.

Another essential part of the jigsaw was the fuel tank, I like the SLEC square tanks and a friend gave me a brand new one (the black-fronted 14 oz/420 cc 'Maxi', the biggest one!).

So...I have everything to push on with the engine and tank installation.


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