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Flamingo 3.5metre by Chris Williams - scratch build

RCM&E Free Plan Build -

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Peter Garsden17/11/2020 07:24:56
1836 forum posts
1446 photos


At first I couldn't understand what these jigs were as it doesn't say so in the article. Then I looked at Chris's photos and realised these jigs hold the wing for the top sheeting being applied. They are higher than the jigs being used now and come later on. The jig from R9 to the tip has to be made out of 2 pieces of 36 inch sheet so good idea to buy 48 inch which doesn't come in the pack incidentally. These jigs are home made and a bit of a challenge using a long piece of angle aluminium as a guide.

Peter Garsden20/11/2020 07:16:45
1836 forum posts
1446 photos


The routine advised was to insert about 6 webbing plates out of .8mm ply along the wing to give it some rigidity, but omit at this stage R2 until the webbing was glued either side of the spars between R1 and R3. This is done with the wing still on the jig shown earlier. I thought I could put all the webbing this way but the advice is correct to take the wing off the jig and glue it in from the bottom with better access.

Before inserting R2 in its 2 halves, one has to glue in with epoxy the dihedral ply mount shown here. NB you have to be careful to ensure that the brass box fits the gap. For instance I found the part 3mm too long where it should butt up against R3 and it had to be trimmed a little at the back and top and bottom so that the brass box would slide in easily.

With hindsight, should I have glued it in now or does it slide in and be glued later? Have I made a boo boo?

Edited By Peter Garsden on 20/11/2020 07:27:49

Edited By Peter Garsden on 20/11/2020 07:29:18

Edited By Peter Garsden on 20/11/2020 07:31:15

Peter Garsden20/11/2020 07:23:46
1836 forum posts
1446 photos



This shows the gull break at R9 where one is advised to glue in some wing webbing - incidentally with the grain running vertically not horizontally as usual. I am also going to bridge the joint in the balsa false leading edge with some 3mm as advised.

This picture also shows the extra half ribs R8A and R10A glued in place to take the piece of sheeting which spans this gap later on.


This shows the tip of the wing, some selected webbing glued in, and the overlap of the spars for cutting off when set. I know this is pretty obvious but it is worth saying. To cut them to size, I rested the spar on some block balsa then used a razor saw to avoid an unclean joint.

Also trimming the aileron spar and false leading edge to correct width will be tricky. I will use my razor plane and the handy long sanding tool mentioned earlier. Works very well.

Edited By Peter Garsden on 20/11/2020 07:25:32

Edited By Peter Garsden on 20/11/2020 07:32:59

Peter Garsden21/11/2020 08:36:29
1836 forum posts
1446 photos


This photo shows the butt joint in the aileron spar which I have reinforced with a piece of 1.5mm balsa and the main spars which are reinforced each side (unlike the rest which are clothed only on the front face) with webbing..The join would otherwise be weak.

Peter Garsden21/11/2020 08:40:33
1836 forum posts
1446 photos

So to the sub spar which only sits to the front of the main spar outside the webbing and ends between rib 21 and 22. I found there were not enough 3mm square spruce lengths in the wood pack so have ordered 8 extra. This may be slightly too much but better to have too many etc.


First I used my handy Tamiya saw to cut the edge of the notch on each rib by lining up an off cut of spruce.


Then my handy 3mm Permagrit file which I use a lot - don't know how I used to manage without it.

Peter Garsden24/11/2020 07:00:55
1836 forum posts
1446 photos


Chris advises that the bending of the spruce spars can distort the wing thus a straight edge should be clamped to the aileron spar in order to keep the structure true. I used a piece of angle aluminium which worked a treat. The pictures show clamps to hold the sheeting down but there is so little to grab that I found pins better - the Graupner pins have such sharp points that one can make them stick in the spruce. Masking tape at the front is best to hold the aliphatic until it dries. This is the underneath of the wing which one covers first before jigging up from underneath..

Peter Garsden24/11/2020 21:22:39
1836 forum posts
1446 photos


Not mentioned on the plan as far as I can see but referred to in the RCM&E article is reinforcement of R2 which serves to strengthen the mounting of the 3mm brass tubing to take the incidence pin. You can see here that the undercamber of the wing means a straight edge just won't do.


So I got out the laser cut scarp and drew a line on the 0.8mm ply so as to trace the correct shape.


Glued in place but first of all drilled with 3mm - also R1. Not altogether clear is that R1 will also be capped with 0.8mm ply - much needed for strength. The brass tube will be reinforced on all sides with 3mm and 2.4mm balsa and lashings of epoxy.

Peter Garsden24/11/2020 21:29:21
1836 forum posts
1446 photos


In this photo one can see the slightly bent with steam to follow the curve 6mm x 6mm balsa reinforcements top and bottom which dictate the edge of the 1.5mm sheeting top and bottom. For now all sorts of detritus have to go into the wing before the top sheeting such as wires for the servos, and here 2 x 3mm ply blocks (plan say 3mm but I don't think that will be deep enough - I used the discarded F1 to F4 3mm ply parts rather than throw them away) for the wing retaining hooks to screw into.

The question is - should I use 6 pin multiplex plugs or not? I do favour them. It saves time faffing around with 4 plugs and sockets.

Edited By Peter Garsden on 24/11/2020 21:29:52

Ron Gray25/11/2020 06:24:21
2533 forum posts
1013 photos

Gradually getting there Peter and a great reference article for when I start mine.

Peter Garsden25/11/2020 13:52:09
1836 forum posts
1446 photos

Thanks Ron. Trying to concentrate on the pitfalls and learn from where I went wrong.

Anyway, have decided to use the Multiplex plugs. I will build a step for the plug to sit on and to stop it falling into the gap between R1 and R2 - next job I think.


Whilst Chris's photograph showed this underneath sheeting missing when jigged up, I decided to glue it in to provide a full rest for the wing when on the jig. Otherwise there would be a 1.5mm gap.


I also installed the capping strips under R18, and 26 which is where the 4th and 5th jig supports sit for the same reason.

I am going to reinforce the jig sitting under R9 as that takes the most weight and can snap under the weight. I am also going to attach 6mm x 6mm legs to keep them upright as you will see next.

Ron Gray25/11/2020 15:59:39
2533 forum posts
1013 photos

For multi servo / wing connections I either use Sbus or Maxlock connectors, as per the Multiplex connectors it results in just the 1 lead going to the RX.

Peter Garsden29/11/2020 11:58:30
1836 forum posts
1446 photos

Thanks Ron, I have ordered some Maxlock connectors and they have arrived. Just the ticket. I didn't even know they existed. Thanks. I have attached a female plug to the wires I have inserted into the wing.


I was intrigued about the wing root profiling part that was in the kit of parts. It is 1.5mm rather than .8mm which is the thickness shown on the plan to line the end of the wing. I wanted to check, however, that the brass tube I had drilled a hole for was in the right place. When I compared it with this rib you can see it is slightly out by about 4mm. I checked the part against the plan and it was correct. I also measure the plan - again the distance from the trailing edge that I had drilled the hole was correct? Mystery. I can only assume that the undercamber of the wing toward the trailing edge is the culprit.

Anyway, I filled in my hole with P38, attached this part to the wing with spots of cyano and drilled the hole in the right place. It is also not half way up the rib but slightly off centre to take account of the positive incidence of the wing - 1.5 to 2 degrees.

There would be no point unless the distance between the wing joiner and this incidence pin tube was correct.


When the top sheeting is on, I will draw round the wing root onto .8mm ply and attach it. Hopefully everything should line up then. The part curiously isn't included in the kit.

You can also see in the picture the Maxlock connector. They do them in 3,6, 9, and 12 pin configurations and are supplied by 4 Max. See the link **LINK**

Peter Garsden29/11/2020 17:30:13
1836 forum posts
1446 photos the wing top sheeting. I had read Sussex Soaring Blog about this stage which I was not looking forward to it. I did a few trial runs and it was tricky to keep the wing in place on the narrow jigs under ribs 1, 8, 10, 18, and 26. So I decided to not only reinforce jig under R8 with 3 pieces of 3mm balsa (as recommended in the very good blog - here is the link - **LINK**) but also to make feet for all the jig supports - essential so you can pin them down first in position over the plan.


You can see the amount of lead needed to make the wing sit on the jigs. Here are my tips

  1. Clamp a piece of hardwood to the trailing edge near the root as otherwise the weight needed will buckle it.
  2. Pin the jig supports down with pins before you start. Otherwise you will not be able to pin in the supports because the wing will restrict access - especially at the tip and root where it is closest to the bench.
  3. Start at the root with the top l/e sheeting glued down first. I used a combination of clamps with one of the flat pieces removed to catch the piece of 3mm square spruce. Even so they leave a bit of a mark on the balsa. Also many pieces of masking tape which glue well to the sheeting underneath.
  4. Attach the long piece of top sheeting to the tip 2nd making sure you use enough masking tape to seat it properly and weight it down. I used a large piece of lead, and a pot of paint. Chris in his pictures show several batteries.



You can see the reinforcing pieces here and the feet out of 6mm square. I also used pieces of 12mm x 3mm


You can see here the piece of lead placed on the middle of the gull join over R8 to 10 and the reinforcing pieces of hardwood I used.

Edited By Peter Garsden on 29/11/2020 17:31:59

Peter Garsden03/12/2020 00:06:48
1836 forum posts
1446 photos


So on with the spoilers - they are 2 pieces of 1.5mm balsa either side of a piece of .8mm ply with cut outs for the hinges - don't make the same mistake as me - fail to check if the square cut outs in the ply are big enough for the hinges - they weren't for my hinges so I have had to cut down the hinges - do that before you assemble them. This is the plan for the other wing.


Here you can see underneath where the servo and connecting rod will be installed. You can see that the hinge is angled down and lined up so that the top of the spoiler is flush with the top of the wing - about 2mm below the surface.

There is a 6mm balsa frame that is inset into the ribs and lines the spoiler hole. The ribs have to be recessed about 2mm to let in the spoiler.

Cap strips still to go on also a balsa surround for the servo and rails for attachment.

Peter Garsden03/12/2020 00:12:14
1836 forum posts
1446 photos

Finally before adding the root ply facing rib, we need to add the leading edge out of 6mm balsa. Fortunately I had some spare 12mm x 6mm strip which I used. I laminated 2 pieces of 3mm x 6mm for the rest of the length which I also had lying around. Not enough 6mm from the woodpack left.


I know this may sound obvious but I always line the sheeting adjoining the leading edge with masking tape to protect it from chipping with the plane. When I take off a strip of masking tape I know I am down to the level and do the rest with sanding paper having removed the tape.


You can see in this picture the ripped masking tape which means stop planing.


Edited By Peter Garsden on 03/12/2020 00:12:58

Peter Garsden04/12/2020 15:11:52
1836 forum posts
1446 photos


Butt jointed to the trailing edge of the wing is the additional fairing, which is a piece of 1.5mm ply included in the CNC pack. It is a bit flimsy and narrow on its own so I glued a piece of 3mm balsa to the front face. This provides thickness and gluing area. I epoxied it to the T/E by holding it with a piece of masking tape.

The next job is the .8mm ply root facing piece, which I shaped by standing the wing on its end and drawing round the profile - don't sand down the 3mm T/E laminating piece of balsa like wot I did. It should remain proud so as to provide a bit more thickness to the T/E which you can see here is filled in with scrap balsa.


This is the root facing piece - so what glue to use - so as to avoid getting excess glue on the incidence pin brass tubing or the wing support rectangular box I used aliphatic, though I did contemplate epoxy. Obviously it needs clamping in place with masking tape.

I also cut off the brass box to size (I had to file out the ply hole so it was a loose fit to push in and glue finally).

After I had attached the root profile ply rib, I decided to also glue in the brass box. I worried about epoxy bunging up the hole, and thought of pushing in the steel blade at the same time. It is a tight fit so won't need much, so in the end I used Super Phatic which is water based and thin. I used the piece of 1.5mm balsa strip to apply the glue to the inside of the hole and coated the outside of the brass, once having filed it to create a rough surface. It will need some filing down but is fine.

Ron Gray04/12/2020 15:19:15
2533 forum posts
1013 photos

Excellent detailed and ancillary information Peter, I, for one, really appreciate the trouble you’re going to to document this build as it will help me with mine (as I’ve said a few times before!)

Peter Garsden04/12/2020 15:22:39
1836 forum posts
1446 photos

Pleasure Ron. I have tried to concentrate on my mistakes so you don't make them, and bits not covered by either Chris's photos which are excellent, and the magazine article, which obviously can't cover everything. How to apply this ply root profile is a good example of what I mean.

Edited By Peter Garsden on 04/12/2020 15:23:27

Peter Garsden05/12/2020 17:19:45
1836 forum posts
1446 photos


Well, onto the aileron which is all built up. What I didn't realise was that the leading edge is angled inwards to create an angle for the top hinging which is very clever. I was worried that by the time I chamfered the edge to suit there would be no width left.

What it does mean, however, is that the bottom edge of the leading edge spar has to be chamfered to take account of the angle.

First one pins down the trailing edge and attaches 3 ribs, one at each end and the middle with some cyano or Superphatic as I used.

Note the judicious use of engineers squares to ensure the ribs are vertical, and Superphatic which was great.

I then pinned the leading edge to the ribs and left it to dry.

I returned to glue in the intervening ribs all the way along


Then one inserts the cross pieces from 1 to 19. They do not have to be an exact fit.

This was reasonably easy in comparison to what has gone before.

Finally I have planed the top of the leading edge to suit the angle of the ribs, ready for hinging and covering. First of all we need to add the tip blocks and line up the aileron to make sure it fits in position.

Edited By Peter Garsden on 05/12/2020 17:21:00

Peter Garsden10/12/2020 13:19:01
1836 forum posts
1446 photos


This is the finished aileron or nearly as it needs blocks for the horn and some trim pieces on top in .4mm ply on the joints since I am using clear matt film. In order to cope with the change in angle at the root one adds a sheet of 3mm balsa which can then be sanded to fit the join in 3 dimensions.


The wing tips have been added so the port wing is more or less, subject to the above bits finished. I still need to install the servos for the aileron (Corona Metal Geared Flat Wing Servo) and spoiler (An Emax MG 9 gram servo).

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