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Slingsby Kirby Gull scale 1/4

Let us all watch your new project progress.
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SedB
Posts: 36
Joined: 14 Nov 2019, 09:17
Location: Netherlands

Re: Slingsby Kirby Gull scale 1/4

Post by SedB »

Looks good, ready for a maiden on the 11th I guess :D !?

Daniel

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Bovin
Posts: 52
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Slingsby Kirby Gull scale 1/4

Post by Bovin »

Thanks SedB, I guess the maiden will be a bit later, we are all quite a time out of practice :(
There were some small things to do; inspection hatches; first I glued some balsa behind the ply, then I cut with a circular cutter through the outer layer of the ply,
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and added a "handle" from thinned down 2X3mm spruce.
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After staining it will be very visible (I hope)
I made a skid from laminated balsa with alminated spruce and ply as skid
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All the ply work was finished, it had to be stained, I like the staining to be quite light, "just out the factory", but its a matter of choice of course. I mostly use "Bister"an old water soluable pigment. Rembrandt used it. Its a powder, you can make it as dark as you like. Because its mostly water, it takes some effort to get it even, I use a brush and a sponge for even distrubution
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Right wing done,
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. Then 2 layers of dope with filler (porienfuller over here) and 1 layer of boatvarnish.
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Fuselage drying in the shed. Its the biggest I have made, I was quite pleased :)
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Vincent

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Bovin
Posts: 52
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Slingsby Kirby Gull scale 1/4

Post by Bovin »

After the varnish I put on the Diacov, a material I used on the Fokker FG-2 and pleased me very much.
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and put on a ply ring, just as a dummy inspection opening for the spoiler
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Then varnished the Diacov and had a bit mixed feelings about that, some less good varnishing at the bottom, not possible to change it :oops:
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I had also made a wooden device to protect the TE at the wing root, which is very vulnerable (Ifound out :( )
The CG which was calculated with ecalc , 72- 85mm behind the LE. I put it at 80mm. I had to put in more lead than I had hoped
IMG_1849.JPG
700 gr, making 950 gr ballast in total. poured in 24h epoxy, so it became a rigid block.
Reason for so much weight was perhaps the weight of the tailplane (145gr). Total weight of the plane is 5200 gr with struts (2 X 10mm carbon wingjoiners) giving a wing load of about 55gr/dm2 and 5600 gr without struts (2 x 10mm steel wingjoiners) giving a wingload of about 59gr/dm2.
After fitting the receiver and programming the transmitter I discovered a nasty problem :( , the ailerons didn't come well in their neutral position. Now I could put the CG alright and I had to put in more lead than I had hoped
/IMG_1849_126.jpg[/img]700 gr, making 950 gr lead in total. poured in 24h epoxy, so it became a rigid block.
Reason for so much weight was perhaps the weight of the tailplane (145gr). Total weight of the plane is 5200 gr with struts (2 X 10mm carbon wingjoiners) giving a wing load of about 55gr/dm2 and 5600 gr without struts (2 x 10mm steel wingjoiners) giving a wingload of about 59gr/dm2.
After fitting the receiver and programming the transmitter I discovered a nasty problem :( , the ailerons didn't come well in their neutral position.How did that come? To avoid problems with the steering cables I made the servo arm exactly as long as the rudderhorns. Because there was some friction in the pulleys and the servo arm was long , it didn't centre properly. What to do? I discussed it (at 1.5meter distance) with my friend Adri (from the anemometre on the Fokker) who had an identical problem already solved. He made a angled servo arm. I made a crude drawing and with a compass(?) I constructed the angle on the servo arm, sorry, its analog . In this drawing the servo arm is half of the aileron arm.
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I converted this angle om a circular servo arm and had to drill an extra hole
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Glad that I had made an inspection opening in the bottom of the wing root, so I could change the servo arm and adjust the steering cables. (after releasing the kwiklinks (or is it quicklinks?) its possible to slide out the servo and also to uncouple the steering cables from the rudderhorns, so they can be adjusted.
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To my big relief the ailerons worked nicely and returned now to their neutral position :D
Vincent.

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Bovin
Posts: 52
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Slingsby Kirby Gull scale 1/4

Post by Bovin »

Adri made the name sticker and the number on the wing (its modelled in the period before registration was necessary) now the Gull was completed. The sun was shining, so I took the Gull outside for some pictures
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You can see at my face (straight in the sun) that the Gull is quite heavy :(
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Just up to now all my building was already done, this is the actual situation and the Gull is waiting for its maiden. Hopefully that won't take to much time, but not this weekend!
Some things in hindsight, I built the horizontal and vertical stabilizer mostly in ply (like the real thing), maybe building it in balsa with the D-box in ply should have made a difference. Also having a scale interior made it impossible to put servo's more in the front. That could have saved (mostly by less ballast) maybe 500gr.
I am very curious how it will fly, I'll keep you informed!

Vincent.

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Philkiteflyer
Posts: 76
Joined: 17 Mar 2015, 21:53
Location: Invercargill, NZ

Re: Slingsby Kirby Gull scale 1/4

Post by Philkiteflyer »

Vincent, that is work of art. I am VERY jealous . . :mrgreen: :mrgreen: :mrgreen:
I wish you luck for your maiden.

Phillip C
New Zealand
"Keep it simple stupid"

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RobbieB
Posts: 568
Joined: 07 Mar 2015, 22:22
Location: North West

Re: Slingsby Kirby Gull scale 1/4

Post by RobbieB »

Vincent, what a fabulous model and a great effort.

Takes me back a lot of years to my Gull 3.

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Bovin
Posts: 52
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Slingsby Kirby Gull scale 1/4

Post by Bovin »

Philip and Robbie, thanks a lot for your very nice comments! I am also an adept of the KISS principle :)
I just received a mail that our field is opening again, first some practice with well known models and hopefully the Gull I can have its maiden this month.

Robbie, your Gull 3 is stil flying?

Vincent

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RobbieB
Posts: 568
Joined: 07 Mar 2015, 22:22
Location: North West

Re: Slingsby Kirby Gull scale 1/4

Post by RobbieB »

It is.
gull_3.jpg

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Bovin
Posts: 52
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Slingsby Kirby Gull scale 1/4

Post by Bovin »

Well, thats a very good looking Gull ! Is it the blue one like the cross Channel one, I presume. It's also pretty big, is it scale 1/3.5?
You have hills everywhere :) , its all flat over here, and not very much thermals as I live close to the sea

Vincent

Phill Tadman
Posts: 398
Joined: 18 Aug 2015, 20:38
Location: South Cambs

Re: Slingsby Kirby Gull scale 1/4

Post by Phill Tadman »

Incredible work!

Phill

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