Flamingo 3.5metre by Chris Williams - scratch build

[Peter Garsden]

I am now on with the starboard wing so I won't repeat the above. The only photo I didn't take was to show the spar jig supports for the wing, which I have kept and reversed from the port wing. It is wise to pin them down in position first before laying over the wing.

I did try to steam bend the 3mm spruce spars but it was not very successful. In fact I snapped the upper spar. Fortunately it is exactly the right length now for the sub-spar which runs along side the top spar for extra strength. I wasn't going to risk re-gluing it and trying to bend it across the join as it would be too weak.

[Peter Garsden]

Just thought I would show you how I reduce the thickness of the false leading edge without breaking the ribs with my plane. On the port wing I sanded it down with a file but I ended up with dips between the ribs where I had applied pressure so for the starboard wing I stretched masking tape along the edge and planed until the masking tape started to rip. I was then down to the right level. This saves ripping the plane into the ribs and breaking them.

Apologies if you already know this trick but it is a good one.

[Peter Garsden]

You can see that I didn't make the same mistake on this wing to omit the brass wing support box and leave the slot open. It is much easier to glue in the box at this stage whilst one has the 3mm ply open and slap some epoxy into the joint. It will be closed up with 2 long grain webbings made out of .8mm ply like all the rest. You can see the other webbings to the right of the image.

This makes for a very strong yet light construction.

Next of course are the sub spars to be added outside and at the front of the spar and webbings to double up and give you 6mm spars all the way to R22 where it is ended in a diagonal cut. A spar goes top and bottom. I showed how I cut the slots earlier.

[Peter Garsden]

Sorry there have been no posts for a month but I have been building the other wing, which is duplicated work and therefore not worthy of posting again. Both wings are nearly now complete as you can see

[Peter Garsden]

I have spent today installing the flat wing servos - Corona as recommended on the plan. They basically sit on 2 rails at right angles with the aileron leading edge. You can thus see that they are slighly askew from the main spar and sit between R16 and R17.

You can see that I have mounted the rails in 2 supports made out of 3mm balsa to ensure they sit in the right place and at the right angle. I did this by putting the discarded rib sheets over some 3mm balsa sheet and drew round the outline, then cut them in half before cutting out slots for the rails then glued everything in place, the rails with epoxy, and the supports with cyano

[Rich too]

Sub’d 👍

[Peter Garsden]

Next to figure out were the spoilers. I have never built a model with spoilers before and the physics of their operation defied me. Setting them up, I found a challenge. When closed, the spoiler must sit flat, and when open, vertical and at right angles to the top surface of the wing...hmmm.....

1. I was going to use metal clevis as I normally do but they are too long. Chris shows plastic clevises on his photos which are shorter, but two of them I found too long, so I used one plastic clevis and one ball joint, which is even shorter still.
2. One must put the horn about 10mm from the leading hinge edge so that when open, the control rod sits against the edge of the spoiler.
3. Don't do what I did and line up the closed spoiler with the tip of the control horn. One must line it up with the pivot screw of the servo. This puts the control rod at an angle when closed. When open it lines up in a straight line with the extended servo horn. Then it works.
4. Due to my stupid error, I had to discard my first set of rails and extend the control rod slightly...Duh...

You can see the angle of the closed rod, and the stubs of the first position I glued in the rails.

This picture shows that the pivot screw of the servo lines up with the hole of the control horn below,.

The control horn is a cut off Futaba standard servo control horn 3 holes from the end. I then cut a slot in the spoiler and glued it in, having roughed up the plastic first. This leaves just one hole showing for the clevis.

Edited By Peter Garsden on 17/01/2021 20:35:37

[Peter Garsden]

I meant to add to the above post that the middle of the horn is positioned 10mm from the leading edge of the spoiler

[Peter Garsden]

I have been adding the hinges for the ailerons today. The plan shows 3 but maybe 4 would have been prudent. No matter. I apologise if this is basic stuff but this is the first time I have added flat pinned hinges to a top hinged aileron so I thought I would share my experiences. I have only ever used mylar tape covered with flocked paper before.

One has to make a gap for the hinge in the moving part - in this case the aileron. Chris suggests taping the top surface to hide the gap. I think I will use Blenderm Tape as I am using see through Hobbyking film.

The hinge has to be recessed about 1/32" from the top of the aileron to allow for the thickness of the hinge but as you can see angled downwards on both sides to give it more purchase. If you slotted at right angles there would be too little thickness to hold the hinge.

[Peter Garsden]

Now for the bit I have been dreading - lining up the wings at the correct incidence and cutting the holes for the wing joining tube and incidence pin. Fortunately one only has to cut through .8mm ply rather than thick fibreglass as I did with my Jart.

First, a handy template to mark the correct position of the wing joining tube is marked on the plan so I cut it out. One rests it against F5 edge of the canopy and lines the base up with the join of the fuselage plywood - not such a reliable line IMHO but nonetheless cut away one must.

Obviously one reverses it for the other side. Next job is to make sure the wing will line up with the tailplane. So I attached the tailplane and the elevator with the servo horn to make it solid. I then put a long length of steel bar and tube through the slots to line it up. A tiny bit of adjustment was needed.

[Phil Cooke]

Looks good to me Pete, great work and a major milestone in the build!

[Peter Garsden]

Next one needs a pair of fairings which are made of a face of 1.5mm cut out from the wood kit and fairing pieces out of 3mm lite ply. They are glued with cyano at right angles down the middle and under the holes for the wing joining tube and incidence pin. Make sure you make an opposite pair!

One then slides one side over the wing joining tube, having cut both the bar and the tube to length leaving about 2mm pudding each side which can be filed down later to fit when glued.

Now the wing has to be set at 1.5 to 2 degrees of positive incidence to the tailplane. One uses an incidence meter.

The Incidence Meter - fortunately I have one. It is digital made by Elite Models. I have attempted unsuccessfully to use it before. First I clamped a piece of 6mm balsa to the tailplane and elevator to ensure it was level and at zero. I then attached the incidence meter to the tailplane and set it at zero. It doesn't have to be level as I had assumed because you can zero the meter to set a level.

Difficult to see but the read out is 0.00 degrees. Carefully then one removes the meter keeping it in the same orientation (don't ask me how I know!) and places it over the wing clamping it in position

I put a piece of carbon rod into the incidence tube sticking out about 20mm to feed into the hole in the fairing and hold the fairing roughly.

Again difficult to see but this is set at 1.7 degrees of positive incidence. It is surprisingly easy to adjust the wing until it is correct. Holding a bottle of superglue in the other hand one pushes the wing against the fuselage and runs a rivulet of superglue down the join until set.

Edited By Peter Garsden on 25/01/2021 23:36:47

[Peter Garsden]

I just thought I would have a little assemble because before filling up the fairings with balsa the wings have to be attached to ensure you don't distort the 1.5mm ply out of shape.

[Peter Garsden]

Next job is to fill up the fairings with balsa which needs a bit of shaping to fit. I used the ply cut outs of the formers to mark out the correct curve.

Filling is needed top and bottom. I put the grain vertical in the middle and horizontal at leading and trailing edges.

One starts in the middle with 2 pieces either side of the brass wing joining tube with epoxy then work outwards, I used cyano which seemed to work well. I have ordered a brass large hole maker to hollow out the balsa and ply on each side.

The other thing is that I inserted 2 short lengths of brass tube to house the incidence pins. I pushed them onto the ends of the carbon rods to mark their correct position for the holes to be cut.

[Peter Garsden]

Next the tow release. This is a simple device from Multiplex which involves a wire being retracted from within a tube to release the tow line.

It has two ridges which can grip onto a balsa or foam nose cone but in this case we have a polyester resin solid nose so it is necessary to file down the ridges which are 12mm down to the 10mm hole which I drilled. I put it in my pillar drill and attacked it with a metal flat file.

The instructions require a 3mm od and 2mm id tube (I used an inner from a Sullivan snake) which fits into a hole in the rear of the release and a piece of 1.3mm piano wire. Fortunately I happen to have some in stock.

I filed down the tube then roughed up the surfaces to provide a key for epoxy mixed with microfibres having attached the snake inner. One must make sure that the front does not protrude from the nose and is flush.

The tube will have to be trimmed and the servo attached to the side of the fuselage with a piece of shaped balsa, and some epoxy once we have attached the control wire to the servo control horn in the correct position. One has to make sure by adjusting the hole on the servo that the movement is no more than 10mm.

The idea is that one has a loop on the towline which fits under a bar at the front through which the control rod slides locking it in position. It is released when the control rod withdraws backwards

[Peter Garsden]

Next the tow release. This is a simple device from Multiplex which involves a wire being retracted from within a tube to release the tow line.

It has two ridges which can grip onto a balsa or foam nose cone but in this case we have a polyester resin solid nose so it is necessary to file down the ridges which are 12mm down to the 10mm hole which I drilled. I put it in my pillar drill and attacked it with a metal flat file.

The instructions require a 3mm od and 2mm id tube (I used an inner from a Sullivan snake) which fits into a hole in the rear of the release and a piece of 1.3mm piano wire. Fortunately I happen to have some in stock.

I filed down the tube then roughed up the surfaces to provide a key for epoxy mixed with microfibres having attached the snake inner. One must make sure that the front does not protrude from the nose and is flush.

The tube will have to be trimmed and the servo attached to the side of the fuselage with a piece of shaped balsa, and some epoxy once we have attached the control wire to the servo control horn in the correct position. One has to make sure by adjusting the hole on the servo that the movement is no more than 10mm.

The idea is that one has a loop on the towline which fits under a bar at the front through which the control rod slides locking it in position. It is released when the control rod withdraws backwards

[Ron Gray]

Some more good work there Peter.

[Peter Garsden]

Thanks Ron. I am trying to concentrate on areas not covered by Chris in his photos or RCM&E write up.

I had to choose a servo for the auto-release. The Multiplex instructions said use a decent servo even though there is not much pressure upon it. I looked in my supplies and found that I had a surfit of Hitec 85mg servos which is a good metal cogged high torque servo. Bearing in mind that the control rod is at quite a bend, I decided to use it instead of a low torque cheap servo which had been the intention.

I used laminating epoxy mixed with microfibres as opposed to epoxy glue to attach the servo to the ply mount so as to make it easier to remove, once having roughed up the surface.

I then had to decide how far from the nose I installed it. The plan showed it under the front ply floor of the canopy but that gave it quite a bend to one side and thus strain. As I was using a powerful servo I decided not to mount it further back and thus at a less acute angle.

The instructions say that the connection to the servo horn should be at 12 o'clock rotating backwards to 8 o'clock to release the tow release. The length of the Z bend had to be shortened to avoid contact with the servo pivot.

Edited By Peter Garsden on 01/02/2021 18:47:24

[Peter Garsden]

This is the cockpit instrument pinnacle with dials printed out on glossy photograph paper. and glued to the .8mm ply facia and painted.

[Peter Garsden]

Interestingly, the above photo was taken on top of the BMFA article from the mag on taking achievement tests.

Next was to make a pair of headphones for my pilot. I made them out of lengths of 30Amp fuse wire and balsa wiht the microphone made from Micro Putty.

[Peter Garsden]

In order to level up the wing join one uses P38 Polyester Filler. One has to make sure to run a knife down the join before it sets - quickly.

Incidentally I have given the ply a coat of Balsaloc so that the White Solartex will adhere to it.

[Peter Garsden]

I have now moved onto covering. As recommended by Chris, I am using Oratex painted white and red for the fuselage, clear Hobbyking film for the open structures on wing and tailplane with red trim on the tips or wing tail and fin.

I had to order the Hobbyking film from China. I am very impressed by it and it goes on very well. Unfotunately it exposes all errors and white filler of which is there is fortunately "not a lot".

To get the right shape for the wing, I made three paper templates. I will also use them cut down for the outline of the white. I am, however, going to paint the joins with Covergrip by Deluxe Models to smarten up the adherence of the joins. As Chris recommends one has to turn the iron down slightly - I think to 100 degrees celsius to stop the edges shrinking and wrinkling when the heat is applied.

Edited February 11, 2021 by Peter Garsden

[Peter Garsden]

I have finished covering the wings and will post some images later. I am now onto the fuselage which will be covered in White Oratex for all areas other than the nose, wing fairings and parts of the skids underneath which are difficult to cover without creasing. The whole fuselage will be painted with white undercoat then airbushed. The uncovered areas will be painted with 5 or 6 undercoats to hide the edges of the Oratex flatted down then finished with a top coat and varnish.

 

Meanwhile the canopy. This model is supplied with the 5 metre version of the canopy which is much larger. Only the front third is used the rest discarded.

 

 

One can see here using good quality nail scissors to pair down the canopy bit by bit with the covering still attached to protect it from scratching. Once it was paired down to a reasonable size, I taped it to the fuselage and taped thin masking tape to mark the cutting lines.

 

 

Once cut to size, I laid the canopy onto the fuselage, the frame having already been painted, and used Zap canopy glue to attach it. I will leave the glue to dry clear overnight then remove the tape.

[David Ashby - Moderator]

Looking terrific Peter ?

[Peter Garsden]

Thanks David. I have to say this is quite a challenging but still rewarding build.