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Flamingo 3.5metre by Chris Williams - scratch build

RCM&E Free Plan Build -

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Peter Garsden21/10/2020 21:53:53
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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.

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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 Garsden21/10/2020 22:12:19
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1815 forum posts
1419 photos

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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 Gray24/10/2020 10:55:01
2452 forum posts
992 photos

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 Garsden24/10/2020 13:09:35
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1815 forum posts
1419 photos

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 Garsden24/10/2020 13:19:51
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1815 forum posts
1419 photos

Here is the assembled rudder apart from the front block.

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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 Gray24/10/2020 13:50:20
2452 forum posts
992 photos

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 Gray24/10/2020 14:38:44
2452 forum posts
992 photos

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 Garsden24/10/2020 15:03:22
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1815 forum posts
1419 photos

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 Garsden24/10/2020 15:32:55
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1815 forum posts
1419 photos
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 Gray24/10/2020 16:00:49
2452 forum posts
992 photos

Horn above elevator, hidden in shroud?

Peter Garsden26/10/2020 17:48:30
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1815 forum posts
1419 photos

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How to form a template for the rear section of the fuselage with a cut out for the fin and tailplane?

First of all I tried cardboard from an office file but found it too stiff. Maybe thinner card might do, but in the end I resorted to paper which is much easier because it bends over the shape easier. Whilst it worked with the front ply sheet, the more acute bend at the rear was too sharp.

  1. I ran my fingers over the join with the other ply shroud and made a mark in the paper. Having roughly cut the paper to size and butted the front up against the front ply, I made a mark for the middle to line it up properly.
  2. It is important to pin it in place to stop it moving whilst the remainder of the marks are made.
  3. I shone a torch behind the paper so I could see the structure through it. This helped me mark each side where the join is made with the horizontal spars.
  4. To mark a line for the edge of the tailplane join I used a 4B pencil and rubbed a mark over the join.
  5. Remember to leave an overhang of about 20mm at the rear to grip the fin and provide a shroud for the Rudder Robart hinges.

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I have always used Deluxe Materials Aliphatic before which has a better grab coefficient I think than Titebond. I made the mistake of getting the standard glue which isn't waterproof so bought this instead. I think it probably sets a bit quicker but is not as gloopy. The jury is out at the moment. I probably should have bound the ply onto the fuselage with masking tape as Chris shows in his pictures. I will try and insert it before it dries completely.

Edited By Peter Garsden on 26/10/2020 17:50:35

Peter Garsden26/10/2020 17:56:51
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1815 forum posts
1419 photos
Posted by Ron Gray on 24/10/2020 16:00:49:

Horn above elevator, hidden in shroud?

Not a lot to attach to in that the joiner is only 6mm balsa, unless you used 2 piece of wire instead of balsa with a piece of flattened brass tubing Also the fin post would get in the way, so you would have to make a hole in it so as to provide some clearance

Peter Garsden27/10/2020 20:48:27
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1815 forum posts
1419 photos

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In this photo one can see that the rear upper sheeting has held well. As for Titebond, I like it but one has to put quite a lot into the joint on both service I would suggest and clamping is more important. It does, however sand well. I have filed down the sides to accomodate the tailplane with flat and round files. I tried it in situ and it is level - relief.

The fin has been offered up to the fuselage and it fits. In error I cut too much back but it matters not. One can see the robart hinges and the slots cut into the rudder to accomodate the pivots.

In order to check that the fin is vertical one clamps a ruler to F5 in line and line it up with the fin.

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Peter Garsden27/10/2020 21:02:04
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1815 forum posts
1419 photos

I have also put together with cyano, the framework for the fin shroud that hides the tailplane bolt head and trims it in line with the tailplane. One then gets a piece of .8mm ply in the cut out parts which has to be steamed and bent round the former.

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This is a bird's eye view of the top of the tailplane support showing the join of the plywood, holes for the plastic bolt and the 2mm carbon positioning rod.

One can also see the ball link into which the control horn rod for the elevator must slide. The whole thing does fit together, just. The important thing is to make the control rod so that it is held in position but is not tight so it can move freely.

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Peter Garsden28/10/2020 23:06:06
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1815 forum posts
1419 photos

The Fin shroud which hides the head of the bolt, is detachable, and fits over the sides of the fin is a clever design, as i is the whole plane. It is made tight enough to slip over the fin, stay in place and not slide off.

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I had to throw away the first attempt at a shroud because as I was trying to mate it with the leading edge where the curvature is very acute, it cracked and snapped partially leaving a tear. As there is quite a lot of .8mm spare, I made another one by drawing round the original.

This time I took the ply skeleton to the kettle and bent the ply round the former in situ. The glue recommended is cyano so the steam did not dissolve it as it would have done if PVA was used. I got it into position so that gluing it up was easy and involved little stress

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I glued the ply in position with 5 minute epoxy.

I have lined up the fin and epoxied it to the rear of the fuselage. It lines up nicely with the ruler at F5 but the height of the cover has meant that I have had to lift up the fin about 6mm so it will slide on nicely. I have added some balsa at the bottom of the fin, and glued it into position until it dries. I will then trim it to shape.

Edited By Peter Garsden on 28/10/2020 23:08:18

Ron Gray29/10/2020 09:35:20
2452 forum posts
992 photos

I'm beginning to think that a permanently attached tailplane would make life a lot easier!

Peter Garsden29/10/2020 21:02:07
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1815 forum posts
1419 photos

Actually Ron, now having glued on the fin and attached the tailplane a few times it honestly isn't that hard. Much easier than I predicted.

Peter Garsden31/10/2020 06:29:22
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1815 forum posts
1419 photos

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This shows the rear lower paper template glued with pritt stick spots onto the .8mm ply. They have been outlined by taping them to the fuselage sides and marking the outlines with creases by pressing on them then marking the creases with a 4B Pencil. I have abandoned the cardboard. Works well. Important to keep a right and left with little markings to show the inside and outside.

Before gluing on one has to make the hole or holes for the rudder controls. I am using closed loop as intended by Chris so have purchased some outers from SLEC. At the outlet one creates a slot then glues to the inside some 3mm balsa doublers.

Peter Garsden31/10/2020 19:35:54
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1815 forum posts
1419 photos

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Before attaching the lower rear sheeting one has to thread the closed loop tubing through the holes in the formers eventually exiting into the cockpit, to be trimmed back later.

Peter Garsden31/10/2020 19:52:04
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1815 forum posts
1419 photos

Next I decided to attach the control horns to the Rudder. Chris advises to use 3mm Multiplex horns which I have never come across before. The plan mentions wooden dowels drilled out to take the threaded horn base. Chris says, however that he now uses carbon tube, so I invested in some 5mm outer, 3mm inner tubing.

I drilled a hole which has to be angled towards the hinge so that the pivot for the closed loop attachments are on the hinge line.

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I will glue the horns in when the covering is on.

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