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Flamingo 3.5metre by Chris Williams - scratch build

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Peter Garsden22/09/2020 14:22:50
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20200922_133305.jpgI have decided to build a scale glider as I already build PSS models. This one, however, will involve some building challenges I have not encountered before such as steaming thin ply round fuselage formers, gull wings, and, hopefully, a crack at some aerotowing.

This glider caught my eye as a free plan in RCM&E because it said it could fly in most weathers. I thought I would be able to slope it as well as trying towing it up from the flat field.

My wife ordered the short kit from Sarik for my birthday. It arrived with voluminous quantities of beautifully laser cut balsa and ply as well as some strip wood, and a wood pack of 1.5mm and 6mm sheet. Lots to have a go at.

The plan came on 4 sheets. I worked out that I would have to tape together the fuselage side view from 4 separate sheets. I didn't fancy that so contacted Chris Williams and asked if he had a one sheet plan. He most helpfully and generously let me have not only the one sheet version with both halves of the wing, but also a set of build photographs which I am sure I will find most helpful.

I sent the pdf files off to Derick at Model Plan Printing - **LINK**l . He printed off just what i needed immediately and sent it next post - great service Derick. Thank you.

I already have the article from the back copy of the magazine which has been studies copiously, so I am about ready to start.

Edited By Peter Garsden on 22/09/2020 14:23:16

Peter Garsden22/09/2020 14:25:47
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I forgot to mention the massive canopy. It is huge and is really for the larger 5 metres wing span version. I thought I had the wrong one but if you read carefully it tells you that you just cut down the large one and use that from the front and top - note to self - read carefully.

Huge sheets of ply and also the large plan laid out ready for cutting up.

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Peter Garsden23/09/2020 08:16:14
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Flamingo 3.5m Glider

This is what the glider should look like when it is finished. I hope mine looks as fine. This is the red and white version. Chris Williams flies a white yellow and blue version.

Peter Garsden28/09/2020 15:38:14
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I have made a start. Always an ice breaker.

Chris has kindly sent me his collection of build photographs which are invaluable and very helpful. In fact I asked questions which he answered promptly, some of which I could have worked out from the photographs.

This is his overview of the first half of the fuselage which you build over the plan.

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The entire fuselage is covered in 0.8mm ply so one has to glue 6mm border pieces to give the edges something to attach to

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You can see in the bottom right a piece of 6mm square which are added after the formers and the keels go down as well as a 6mm piece of triangular which is attached to the wheel axle mounting piece of 3mm ply. All formers are ply.

My mistakes:-

  1. The false centre keel should end before F5 whereas mine continues through it which is wrong and makes F5 slightly out of line. The shaded piece should not be there

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  2. Between the last 2 formers from the tail should go the tailplane support piece whereas I stuck a piece of 6mm square. Wrong. Not a problem though, I will just glue it to the outside and carve the support piece to suit. I have put crosses on the offending piece.

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Peter Garsden28/09/2020 16:21:29
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I have ordered a Proxxon circular model saw to cut all the 0.8mm and 1.5mm ply parts there are as one gets 3 large sheets. In the meantime I am cutting my ply with a Japanese saw which cuts on the back stroke and has fine teeth - very useful tool. Not easy however with a big sheet.

I did the following measurements:-

  1. Each plank should be 9mm
  2. From F5 to F1 one has to lose some width because of the curve down to 6mm.
  3. The curve starts at F3 which is 176mm from F1.

I used a bendy ruler to form a curve. I will match the next one to it.

I used some steam to form a curve in the first piece of ply - helps a lot, then used aliphatic to glue the first piece down - PVA is a bit old hat now. You can see that I used a mixture of masking tape, spring loaded clamps, and masking tape.

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My friend Keith gave me this planking bending machine which I am going to give a try. It is used in boat building to curve ply keep pieces. Might negate the need to use steam - we will see?

Nick Somerville28/09/2020 17:56:29
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Hi Peter, lovely choice of model and a practical size too. I have seen many of Chris’s gliders fly over the years and cam attest to their flying qualities. His building skill and speed considering he scratch builds is also something quite remarkable. I am slightly surprised at the use of .8mm ply for the fuselage. Although I haven’t built any of Chris’s models I built a number of Cliff Charlesworth designs and also a John Watkins designed Kirby Kite. All at 1/4 scale and fuselages skinned with .4mm ply. Cliff’s technique was to add 3/32nd balsa thickener to each of the half ply formers to increase the glue land. Thin card is used to make a template for each bay to be Covered and then scissors are used to cut the ply with the pattern traced on. Adhering the panels can be done either with superglue, or just as effectively evostick. My DFS Reheir At 4.75 m not only had .4mm ply for the fuselage but also the entire wing was sheeted with .4mm. Lightweight glass cloth on top prior to painting. A friend built the RehIer at the same time and planked the fuselage with 3/32 balsa and sheeted his wings with 1/8 balsa, then covered with either silk and dope or Solartex (can’t recall) The differing Weights of our two models were negligible. I have some pictures of these models in the building state so send me a pm if you are interested in seeing them.

Edited By Nick Somerville on 28/09/2020 17:57:51

Peter Garsden30/09/2020 14:50:14
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Thanks Nick - very interesting. This is my first scale glider and it is a building skill learning curve for me and one which I am enjoying. I have never worked with as much ply sheeting though have planked a fuselage in 3/32 balsa which is a lot easier because it bends. This is hard but worth it as it will produce a hard fuselage. I see what you mean though .4mm ply would be a lot easier to work with. So far so good. We will see. I will pm you re the other photos.

Good point about the planking method. Certainly another builder of the same model used 3/32 balsa instead of ply as he thought it would be easier. 

This is another excellent blog to cross reference - https://slopesoaringsussex.blogspot.com/2020/05/flamingo-hw-4.html#comment-form

Edited By Peter Garsden on 30/09/2020 14:59:15

Peter Garsden30/09/2020 14:57:11
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Well I have done the forward fuselage 1.5mm planking and turned the fueselage over without taking any pictures - sorry!. Will do some on the port side.

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You can see that I have supported the fuselage on scrap blocks of foam. The parts are so accurate that it goes together very well and easily.

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You can see that I am using a 6 inch steel ruler to make sure the formers are straight and perpendicular.

I have used cyano to glue in the edges of the formers where they join, and aliphatic resin to glue on the 6mm square support pieces to the top and bottom keel. I decided I would do it as I went along to provide the formers with more support rather than adding it at the end when the spruce spare was on.

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Slight deviation from plan which I think works. I added a piece of light 3mm ply additional support to the middle join. This keeps it straight nicely and provides support where it would otherwise be a butt joint. The rest of the formers are supported with cross pieces of 6mm square as you will see when I am further into the build.

Peter Garsden07/10/2020 20:22:35
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The next step is to plank the remainder of the fuselage to fill in the bottom to the keel.

It is one thing to plank with balsa which bends but another entirely to plank with 1.5mm ply which doesn't. I found that putting a bend in the ply to follow the curve with steam from the kettle and hands protected by rubber gloves helps a lot.

Lots of clamps and wrapping with masking tape helps keep the ply in position. Very difficult to pierce 1.5mm ply with pins into 3mm ply. I have bent quite a few.

Gaps do not matter because there will be a thick layer of P38 Car Filler to smooth out the surface, and a layer of fibreglass on the inside.

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Peter Garsden09/10/2020 20:43:15
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You can see that the fuselage is upside down to finish off the planking. Fitting the last piece is a challenge, inevitably. So I made a paper template which was then glued onto the plywood with Pritt Stick and cut out.

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Ron Gray09/10/2020 21:49:05
2378 forum posts
965 photos

I had forgotten that you had started a thread on this model Peter but pleased that you have as I have just placed an order for the glider and will be following in your footsteps.

Did you use the plank bending tool?

Edited By Ron Gray on 09/10/2020 22:01:03

Peter Garsden10/10/2020 10:13:01
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Thanks for the follow Ron. In answer to your question no I didn't use the bending tool. Reason was that I am using planks of 27mm wide rather than 9mm as suggested by Chris. Each plank is scored into three with 2 score marks so as to bend the ply over the curve of the formers.

I used steam to bend each plank with more bend towards the nose. I think this works best.

I do recommend Ron Chris Williams photos of the build and the article from RCM&E which I can send you if you PM me.

Peter Garsden10/10/2020 12:33:11
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This is the final piece for the other side of the fuselage showing the bend I managed to get with some steam. It makes gluing it in position so much easier as I am using aliphatic and a bit of cyano for the inner formers. Mainly masking tape however as you can see.

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The paper template is still glued to the part but does peel off.

 

Edited By Peter Garsden on 10/10/2020 12:51:18

Peter Garsden10/10/2020 12:47:22
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Next the tailplane. Here I encountered a bit of a quandary and had to email Chris. The plan doesn't show the size of the trailing edge but it is 6mm square. The tailplane, however does taper in height towards the tips only underneath so one makes it upside down with the bottom sheeting being added last using jigging supports.

The point is that I presumed that the height of the trailing edge should also taper from say 6mm at the root to about 3mm at the tips. I asked Chris and he confirmed, so before I pinned it down I marked the taper and used my circular sander to sand down the taper.

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The ribs are all very accurate, small and 1.5mm balsa.

First I pinned down the trailing edge flat with the taper uppermost and attached the ribs to it using cyano. They are so thin that instant bonding is better IMHO. I then attached again with cyano the false 1.5mm leading edge which also tapers from root to tip.

Finally the middle solid balsa infill using aliphatic resin and pinned in place again it has to be sanded to follow the contour of the ribs - before is better and easier than after gluing in place. Scrap can be used.

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Also worth mentioning is that the upper and lower sheeting overlaps the trailing edge spar by about 6mm leaving a gap into which the rounded elevator will fit and rotate using the robart hinges. It isn't very clear on the plan but Chris kindly confirmed that my understanding is correct. To be fair the photos of the build confirm this. Here is the photo of the finished tailplane to confirm

p1050348.jpg

Edited By Peter Garsden on 10/10/2020 12:49:03

Ron Gray10/10/2020 13:14:12
2378 forum posts
965 photos

Coming along nicely Peter and I certainly appreciate highlighting the 'gotchas' which will hopefully make my build a bit easier.

PMd you btw.

Peter Garsden11/10/2020 16:30:59
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1781 forum posts
1367 photos

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One takes the open structure off the board in order to attach the top sheeting first as this is flat whereas the underneath is tapered. As the sheeting is bent at each side one must use clamps (or use cyano I suppose but I don't like the instant grab of it)

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In order to attach the bottom sheeting one attaches 3 jig supports supplied in the kit of parts to the centre and each tip bottom sheeting. In order to encourage the curvature I painted ammonia to one side which curled up the 1.5mm sheeting nicely. I then glued with aliphatic and weighted it down. Not show here are the clothes pegs to the leading edge to give extra adhesion.

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Here you can see one of the tip jig supports supporting T8 and the bottom sheeting with lead atop.

Peter Garsden11/10/2020 16:33:56
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Next F1A which sits against F1 to provide support for the front of the canopy. Having glued it in one must put 1.5mm ply on top to cover the gap before doing the car filler mega spread.

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I used the sanding disc to take the edge off the top side and sandwich it against F1 at an angle to give more gluing area.

Peter Garsden12/10/2020 19:01:54
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I ummed and awed as to whether to bend the plywood round the top of the fuselage at this stage or whether to cover the front plywood with car filler P38 first. I decided that a more rigid structure was better and decided to make the plywood top cover first.

One has to make a cardboard template and cut it to size so that the join is in the right place.

How then to bend it into shape. I found that steam was best to tease the curves into shape, but first of all using some wide masking tape to hold the bend in position. I also wet the outside and used an iron to help the bend stay in position

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I then smothered the balsa and ply frame, which had been sanded back to follow the curve of the formers, and bent the .8mm ply round the formers, turning it upside down to hold the ply in position with lots of clamps and clothes pegs.

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Peter Garsden13/10/2020 14:36:48
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When glued in place the ply looks ace. Very difficult to line it up perfectly, best way is to mark the middle both on the fuselage and the sheeting and line both up together (I didn't!)

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Peter Garsden13/10/2020 14:46:50
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As F1 only stretches the inside of the 1.5mm ply, one has to glue a layer of ply in small pieces over the top of F1 and F1A It will all be covered in filler anyway.

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This photo shows that I have put on a layer of P38 Filler. Needless to say I used the dregs of my small 250 gram pot of filler which I realise is past its best - gone lumpy - DON'T as it doesn't spread. My new pot of 600 gram is much runnier and more fit for purpose.

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Here you can see the awful lumpy top, and (if you look carefully enough) the smooth right side which is the old and the new P38. You can't mix enough to cover the whole fuselage at once and will have to mix in several portions. It dries very carefully.

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