Flamingo 3.5metre by Chris Williams - scratch build

[Peter Garsden]

Before any more filler goes into the nose I attached 3 pieces of lead for nose weight. I simply copied Chris's photos so hope it will not be too much - a complete guess. Will let you know. Screwed in with self tappers. This space will now be covered in filler.

[Peter Garsden]

This shows short self tappers attaching 3 sheets of lead for ballast as suggested by Chris in his photos. No idea what will be needed so just a guess. They cannot be removed because the nose is filled with P38.

[Peter Garsden]

This is the shoe horn sander which is really effective for sanding down the filler. You have to be careful not to go too far. There are a few holes that will need filling and re-sanding but a lot of weight has been removed.

[Peter Garsden]

On with the elevators - you can see that there are many parts to the trailing edge so I marked them with numbers. There is a layer of 3mm, then 1.5mm ply then another 3mm balsa layer. The ribs slot onto the ply. Cyano is best as it sets fast though I did experiment with Superphatic which I do prefer. Think I will use it for the ribs.

This is the finished trailing edge which you make before attaching it to the pinned down trailing edge and the tip rib.

[Peter Garsden]

You can see the filled and sanded nose in the foreground and inside the cockpit I have removed the temporary formers F2,F3, and F4 and the temporary middle spar. This leaves a fragile hole which Chris advises should be lined with fibreglass and resin, the outside having been filled with P38. He recommends polyester resin which not only stinks but also seems to set too quickly for my liking, so I always use epoxy resin as here. The secret is to always dab the cloth with the brush and not try to stroke it as all you will do is pull and distort the fibreglass threads and pull it out of shape.

[Peter Garsden]

Having offered up the tailplane support sides and marked the shape on the middle keel, then filed away the excess to give the shape of the bottom curve of the tailplane, I cut away the rear 40mm which will allow movement of the elevator horn with the connection within.

Then one glues in and lines up front and back and clamps into position. After it is dry I will cut away the excess.

[Ron Gray]

I’m guessing that you put the filler on first as the temp formers give the fuse strength for the subsequent sanding, otherwise I would have thought it more logical to glass the inside then fill the outside?

[Peter Garsden]

Posted by Ron Gray on 16/10/2020 08:53:04:

I’m guessing that you put the filler on first as the temp formers give the fuse strength for the subsequent sanding, otherwise I would have thought it more logical to glass the inside then fill the outside?

Yes indeed Ron. Filler first before removing temporary formers so as to provide strength. The other issue is that when applying the filler some seeps through the cracks which are then sanded down before applying the cloth and resin. The formers all came out without too much difficulty.

[Peter Garsden]

Chris recommends sanding down the trailing edge whilst the elevator is still pinned down to the board. I found a scrap piece of 6mm balsa and applied with 60 grain emery cloth with Pritt Stick glue on both sides. Works really well.

[Peter Garsden]

I glued the tips to the elevators and sanded them down. I tried them against the tailplane. The leading edge of the elevator is meant to nestle inside the trailing edge of the tailplane. It needs quite a bit of reduction so as to fit the robart hinges.

Before we glue on the rear .8mm plywood the mounting for the tailplane, holes for the bolt and positioning pin, the elevator horn, and the elevator pushrod with servos have to be added.

This bit is quite important because the tailplane has to be in the correct position relative to the under tailplane support, it has to sit centrally, and the tailplane has to be in line. I first of all drilled the holes in the tailplane and clamped it in position so it wouldn't move when drilled. Maybe it is better to drill right through both at once?

The plan suggests using 2mm threaded steel rod, but I decided instead to use carbon rod as is common. When installed, I was concerned that they were enlarging the balsa holes so spread on some cyano which hardens up the balsa nicely.

I wasn't happy attaching the 5mm clawed nut to the balsa which I thought was too flimsy, so I attached the nut to a piece of 6mm balsa. I still wasn't happy so laminated it with a piece of 1.5mm ply which you can see. The underneath was not level so I packed it up with a balsa wedge. After several trial runs I mixed some epoxy with some microfibres, covered the bolt with Vaseline and screwed the whole thing tight to set, first checking that the tailplane was level with where the fin would be. I did this by placing a steel rules in front of F5.

[Peter Garsden]

In this picture you can see the elevator horn which is a small rectangle of 1mm brass plate reinforced with copper wire (should be thin brass sheet) and 2mm piano wire soldered to it at right angles. This was something I had never done before and was a challenge. I used my soldering jig to hold the wire, plate and tweezer to push the copper wires into position and heated the plate underneath to melt the solder, firstly having cleaned any oxide off the pieces, and used some flux to key the surfaces.

I then had to drill holes into the brass to take the tiny 6mm screws. They screw into a layer of 1.5mm ply which is glued to the leading edge of the elevator. All very delicate and small scale.

The idea is that a 2mm ball link on the end of the 4mm carbon push rod slides over the rod to operate the elevator.

To allow rearward movement one has to file down a slot in F18. The whole area will be much strengthened by the .8mm ply shroud which cannot be attached until the servos are in place and the elevator control rod attached. In order to keep the rod at the right height in the fuselage one puts in place a balsa support in the fuselage.

[Peter Garsden]

The next excellent tip is to use a round sanding cylinder to put round the head of the bolt and make it easier to remove because of course the fin will be in the way of any screw driver.

The head of the plastic 5mm bolt was slightly too big, so I put it in my power drill and filed it down slightly then glued it in position with cyano.

[Stephen Belshaw]

Your build is coming along nicely Peter, and very quick!

I'm close to finishing Chris's A-Spatz which features similar build techniques, the tailplane for example is identical and uses the same elevator mechanism. The Spatz is a much easier build though, having a slab sided fuselage and no gull wing, but as you say a very enjoyable process - challenging but ultimately very satisfying.

What are you planning to cover it with?

[Peter Garsden]

Thanks Stephen. As you say always better to learn new methods of working and skill and get out of your comfort zone.

So you ask about covering. I am going to follow guidance Chris gives in the RCM&E article and use matt clear Hobbyking film on the built up areas of the wing, elevator, and rudder, whilte solarfilm with trim on the rest of the wings and white Solartex on most of the fuselage, filler on the tricky areas to match the Solartex such as the wing joining box etc then paint to match - white with either blue and yellow trim or red - I have not decided yet.

I did order Solartex Natural but it has a cream tinge so I am going for the Hobbyking version which has to be ordered frrom Hong Kong with a delivery charge of, I think, £15. Not available sadly in the UK

[Peter Garsden]

Before closing up the fuselage we have to link up the elevator, so first of all there is space for standard size Futaba 148 servos 2 abreast no less. There is limited space, but as F5 is angled one can get my handy manual drill in the gap. The rear screws have to be drilled at an angle with 1.5mm drill.

It is very difficult to line up Beech 6mm bearers in a curved fuselage, so I create 12mm balsa support blocks by copying the curve to the side of the blocks and cutting out slots for the bearers to slide into. It helps line up front and back level.

[Peter Garsden]

This is the connecting ball link that the servo activating 2mm rod fits into. I cut off the 2mm studding rod to length to give an overlap of about 40mm, then mixed up some 20 minute epoxy to give enough time to position, adjusted the ball link into position and pushed the controlling rod through the hole then attached the tailplane into position. I taped the elevator into neutral position, once having ensured that the servo arm was at neutral position. It then had to be left to set in position.

To keep the elevator pushrod in position whilst the tailplane is attached and to avoid it dropping out of reach into the bottom of the fuselage one has to build a balsa cage in order to hold it both vertically and horizontally. One also has to make sure that the ball link does not bind the top on full up elevator or come off the bar on full down, so half way up is the ideal.

I lined it up with the point shown on the plan which was perfect when tried with the transmitter. The bend on the rod gives some automatic differential which is also clever as the recommendation is 25mm up and 15mm down.

[Peter Garsden]

I also made up the fin which consists of 2 trailing edges glued together, 4 ribs, the bottom one at an upward diagonal angle and a 2mm false leading edge. The structure is held together with cyano then I cut the 0.8mm sheets to cover each side. One has to make sure the shape is correct so as to tie into the rear fuselage sheeting. It is also important to glue both sides at once and clamp into position until the aliphatic resin sets.

To this has to be added the 6mm leading edge and the rudder.

Edited By Peter Garsden on 21/10/2020 22:12:48

[Ron Gray]

Excuse my ignorance Peter (my kit arrived a few days ago but I'm not allowed to open it until tomorrow as it's a Ruby wedding anniversary present from my wife!) but I assume that the tailplane is made so that it can be removed, hence the sanding drum stuck to the bolt head. How to you ensure that the elevator horn wire locates in the ball joint connector in the pushrod when you assemble it? I was wondering about using a small tailplane mounted servo for the elevator, similar to the ones I use in my F5J models (Bluebird servos) as they are both lightweight and powerful.

[Peter Garsden]

That sounds like a good idea Ron. Didn't think of that. I assume it is a weight argument, though I know the Bluebird servos are very light. Also, using the intended plan method, the linkage is hidden for scale purposes.

I think that as long as there is as little play as possible in the elevator pushrod then it will stay in position to allow you to install it. I was thinking of a length of 2mm rod to line up the ball inside the link. If you then push the elevator to the up position, you can squeeze it in.

And CONGRATULATIONS on getting to Ruby. You must have rationalised your "flying your toys again" arguments to a fine art.

[Peter Garsden]

Here is the assembled rudder apart from the front block.

I found that a rough flat file was better to thin down the trailing edge then the long home made sanding block for the leading edge and ribs. As I am using matt clear film I need to remove the brown laser burn covering..

[Ron Gray]

Thanks Peter, we're no making too much of it but the kids are!

I was thinking of mounting the Bluebird servo on the underside of the tailplane with a small cut out in the fuse. It would then be hidden as would the control linkages. Of course I won't know until I'm allowed to get at the plans!

On the covering front I was thinking of either laminating film or Diacov.

[Ron Gray]

Thinking more about the elevator servo, I'm now hoping that it could be mounted on top of the tailplane hidden within the fin 'shroud'.

[Peter Garsden]

Never used either of the products you mention Ron, but would be interested to know more. Have read the blog on the subject, but my Hobbyking film has now arrived quickly from Hong Kong albeit at a price. That is what Chris recommends for the built up panels. I have sent the natural Solartex back again at a price because it has a cream tinge to it which will not match the white solarfilm I intend to use on the sheeted areas of the wing.

Edited By Peter Garsden on 24/10/2020 15:04:48

[Peter Garsden]

Posted by Ron Gray on 24/10/2020 14:38:44:

Thinking more about the elevator servo, I'm now hoping that it could be mounted on top of the tailplane hidden within the fin 'shroud'.

That is certainly possible assuming you can connect it underneath to a horn somehow in the centre of the elevator connector, or maybe use a metal connecting rod for the elevators and attach it to that? Or just use the existing horn?Must be possible with a bit of thought. I just follow plans I am afraid.

[Ron Gray]

Horn above elevator, hidden in shroud?