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Re: Veron Tiger Moth

Posted: Sat Jun 13, 2020 1:10 pm
by Colin
Well after a lot of expletives the wings are now joined ready for the building up of the centre section.
Wings Joined.jpg
Wings Joined.jpg (956.69 KiB) Viewed 4534 times
Initially I misread the plan when building up the panels. If you look at the image of the plan on the earlier post you will see that where the spars meet the centre section there is a clear solid line across the spars. I took this to mean that the spars were trimmed to this line.

When I came to do the centre section I found that the spars are intended to extend into the centre section and be butt jointed against the opposite spar. This meant cutting back the trimmed spars and adding in extensions.

Then when I finally got to join the wings I made the mistake of trusting the use of the trailing edge stock but found after the joint had dried that the sweep back was too great so I then cut them apart and remade the joint - hence all the little bits of off cuts. Looks a mess but the strength is there so it will be no different once sheeted.

Next step is to add the centre leading and trailing edges and the ribs and then I can start the sheeting.

One tip. If like me you are always chopping up bits of good balsa to make the wing tip dihedral supports when join wing halves, I have found a different method. Simply take one of the ubiquitous coffee stirrers or lollipop sticks and mark on it the correct wing tip height. Then tape the stick to the outer most rib with the mark lined up with the bottom of the rib and voila!
Wing Supports.jpg
Wing Supports.jpg (714.96 KiB) Viewed 4534 times

Re: Veron Tiger Moth

Posted: Wed Jun 17, 2020 11:15 am
by Colin
Well that was a traumatic session - firstly the sweep was the wrong angle, (through my trusting the triangular strip angles and not building over the plan), and then through misreading the instructions I joined the wings using the bottom wing dihedral. So both times I have had to cut the panels apart and re-glue.

So here they are ready for sheeting. Panel joint feels solid but prior to sheeting I will apply some bandage/epoxy just in case.
Top Wing Panels Joined.jpg
Top Wing Panels Joined.jpg (1.09 MiB) Viewed 4530 times
So having made the 8 strut fastenings for the wings, the next stage is to fit the 4 for the top panel and then do the sheeting.

I am starting to think about the modifications needed to add ailerons. I think it should be fairly straightforward if I plan carefully so that the aileron ribs are trimmed correctly.

Re: Veron Tiger Moth

Posted: Thu Jun 25, 2020 3:48 pm
by Colin
Well the top wing is now finished ready for covering at last...
Top Wing Uncovered.jpg
Top Wing Uncovered.jpg (1.06 MiB) Viewed 4494 times
So now onto the bottom wing and the first challenge is the bottom rear spar which is doing a good impression of a banana! Hopefully the warp will steam out, otherwise I'll raid my stock and cut a new one.

Re: Veron Tiger Moth

Posted: Mon Jul 06, 2020 9:40 pm
by Colin
OK - bottom wing now completed...
Both wings.jpg
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So now on to the fuselage and planning for cable control rather than the original pushrods.

Re: Veron Tiger Moth

Posted: Thu Jul 16, 2020 9:06 pm
by Colin
Now have the control sorted out. I'm emulating the full size by having a rudder bar going across the fuselage. Initially I was going to use a strip of fibreglass board but decided to go with ply for now.

Servo Installation.jpg
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The ply is doubled inside the fuselage for strength and will be brass bushed eventually.
Rudder Bar.jpg
Rudder Bar.jpg (636.89 KiB) Viewed 4235 times
I need to get the final control paths and supports sorted before I can complete the top half of the fuselage, so the next step will be to build the tail feathers so I can route the cables.

Re: Veron Tiger Moth

Posted: Sun Jul 26, 2020 12:27 pm
by Colin
Well it's been a while since I last updated, so here's an update.

In the previous post I reported that I had sorted out the rudder cable control bar, and since then I have worked on the elevator cabling. In the full size each elevator is cabled with the cables coming out 2/3 of the way down the fuselage and I have mirrored this. A dry assembly test has shown that the system should work OK.

So now back to the fuselage. In the instructions, the next steps are to do the wing cabane and the undercarriage but I am leaving these to last so I can focus on the top without them getting in the way.

So the next step was to work out where the battery hatch was going to go, and this has finished up between the front former just aft of the cowl, and the rear of the front cockpit. Extra formers where made to fit here and magnets installed for fixing. (Sorry - no pics of this bit.)

So now on to the top section of the fuselage.

The kit provides two thin plastic mouldings for this ...
Kit mouldings.jpg
Kit mouldings.jpg (777.79 KiB) Viewed 4077 times
but having used this approach in the past I knew that they would not be satisfactory as
  • I have trouble cutting to an exact fit
  • Heat shrink film is hard to use on them as bubbles cannot be easily removed
  • If you use paint rather than film, then getting an exact match is hard
So I decided to plank the fuselage instead.

First step - prepare a lot of strip balsa!

Planking prep.jpg
Planking prep.jpg (670.81 KiB) Viewed 4077 times

Re: Veron Tiger Moth

Posted: Sun Jul 26, 2020 12:54 pm
by Colin
Here is the progress to date ...
Planking so far.jpg
Planking so far.jpg (889.12 KiB) Viewed 4077 times
If you have not tried planking before and it puts you off, it is quite straightforward although can be tedious. I tend to do maybe half a dozen strips at a time then have a break.

Here is how I do it.

First of all prepare your planking strips. You need to decide the optimum width and thickness of the planking. Wider strips mean less planking needed - but each strip needs to be thicker so you can get the curve.

Thicker strips give you more leeway when it comes to final sanding, but add weight.

I have gone for 1/16" x 3/16" strips.

To avoid distorting the fuselage you need to plank evenly - so that means a couple of strips each side and a couple down the centre line.

You then work alternately adding a centre strip and a side strip on each side so that you slowly fill the gap.

To fix the strips I use CA and aliphatic, using the aliphatic down the length of each strip and the CA on each former, just doing a couple at a time, holding till set then the next couple. Doing this avoids the use of pins, and also keeps the CA away from the surface where it could cause sanding problems.

Of course the fuselage top is conical so in theory each strip should be tapered to fit, however there is an easy workaround in that you leave each strip full width as far as possible. You then line up a ruler against the mating strip and the new one and trim to fit. (Do this before any gluing and if not quite right you can adjust.)

Do this alternatively for the strip coming down from the centre and the one coming up from the side and you finish up with a neat 'herring bone' finish which will be hidden once covered and painted...
Fairing in strips.jpg
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One final thing - – if you have hatches, as I do – plank them at the same time, in situ, or you may not finish up with a smooth transition. However, every few planks cut through where the hatch is so you do not lose sight of the hatch formers!
Hatch cutting.jpg
Hatch cutting.jpg (702.95 KiB) Viewed 4077 times

Re: Veron Tiger Moth

Posted: Mon Aug 03, 2020 5:01 pm
by Colin
With the planking complete, it's now time to turn my attention to the cabane structure - a wire frame that eventually gets disguised as wooden struts.

One thing I had not realised is that the wires actually come up through the top longerons and so impinge on the hatch sides.
Cabane wires.jpg
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Not only did this mean that the hatch had to be cut into for the wires - it also meant the hatch cover was not so easy to remove. As a result the forward corners have been removed to be stuck permanently to the fuselage.
Hatch Mod.jpg
Hatch Mod.jpg (553.77 KiB) Viewed 3938 times

Re: Veron Tiger Moth

Posted: Mon Aug 03, 2020 5:04 pm
by Colin
So with the main structure done and only the undercarriage and minor fettling remaining before covering I'm now at the stage where the law says you have to put the bits together to see how it looks!
Has to be done!.jpg
Has to be done!.jpg (1.28 MiB) Viewed 3938 times

Re: Veron Tiger Moth

Posted: Mon Sep 21, 2020 7:06 pm
by Colin
Haven't posted for a bit but the model has been progressing.

The cabane structure as per the kit was not too successful. The instructions suggest epoxying a piece of balsa to the rear of the wires and then wrapping with gummed paper. Not having gummed paper I tried using self adhesive label stock, which did not adhere too well and I ended up cyano'ing each bit of the label in stages.
Cabane.png (84.42 KiB) Viewed 2924 times
The u/c shock absorbers are supposed to be the same but instead I covered them with a thin coat of filler, sanded them down and then doped on some tissue. We'll see what they look like once they are painted.

And so on to the covering. The top wing was done with silver Solartex. The lower wing was supposed to be the same but on cutting out the covering I found I only had enough for one of the the four panels required for the lower wing. Fortunately I had a large roll of silver Hobbyking film which matched 100% on colour, and unless you look closely you can't see one is a fabric covering and the other film.

So this is where we are at the moment.
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Next step is to finish the cowl and make the tail wheel assembly and then it's onto the detail work.