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Scratch built Pilatus B4 to 1/4 scale.

Let us all watch your new project progress.
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B Sharp
Posts: 736
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: Scratch built Pilatus B4 to 1/4 scale.

Post by B Sharp »

I’ve been focusing on some of the fiddly bits today. I started with the canopy frame as I am expecting to get my newly pulled canopy mouldings back from Barry at Sarik in the next few days. It’s constructed from 3.5mm ply, held in place at the front with a 6mm dowel and at the rear with 4 x 10mm button magnets. The instrument binnacle has been shaped with balsa block and has then had 0.7mm plasticard wrapped round the shape to give a good flat surface and a slight overhang to the instrument panel.
I have started on the undercarriage doors by bending a piece of 1.0mm aluminium sheet round a form to achieve the curve of the bottom of the fuselage. I have created lips inside the fuselage front and rear of the opening so that the ali sheet sits flush with the fuselage surface. Once I have formed the hinge seats inside the fuselage I will cut the ali sheet in half to create the two doors.
Brian. :) :)
Attachments
Cockpit frame in place.
Cockpit frame in place.
Undercarriage doors during fitting process.
Undercarriage doors during fitting process.

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Peter Balcombe
Posts: 1141
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Scratch built Pilatus B4 to 1/4 scale.

Post by Peter Balcombe »

Very nice Brian :)

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B Sharp
Posts: 736
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: Scratch built Pilatus B4 to 1/4 scale.

Post by B Sharp »

Its been a couple of weeks since I was able to show any progress on the B4. In the background I have wet & dry sanded the fuselage and the wings following the glass cloth and epoxy session.
I have also fitted the canopy glazing to the frame and painted it up. It is just as well that I ordered 2 canopy mouldings as I made a right pigs ear of fitting the first attempt! The trimming and fitting process went ok and it all looked good. However I used “canopy glue” to attach the glazing to the frame before taping it down securely – I THOUGHT! When I undid all the tape it was a right mess. Bits of the glazing were coming away from the frame, some sections had pulled squint and I ended up ripping it all off. :x :x :x I decided to use good old Evostik contact glue for the next attempt and it worked just fine. :?
I have a bit of cockpit detail still to do but I can see “PAINTING” approaching quite soon and I’m not looking forward to that. :cry: :cry:
By the way the more observant of you may have noticed that I have installed a new worktop to my workbench. I had to use Plywood as I couldn’t get hold of 18mm chipboard anywhere. Is chipboard the new toilet paper? :? :?
Brian.
Attachments
The completed canopy.
The completed canopy.

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Barry_Cole
Posts: 1394
Joined: 10 Mar 2015, 09:30
Location: Hampshire UK

Re: Scratch built Pilatus B4 to 1/4 scale.

Post by Barry_Cole »

Is chipboard the new toilet paper? :? :?

I really hope not..............

:cry: :cry: :cry: :cry:

BC

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B Sharp
Posts: 736
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: Scratch built Pilatus B4 to 1/4 scale.

Post by B Sharp »

Life is rough Barry!
Brian.

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B Sharp
Posts: 736
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: Scratch built Pilatus B4 to 1/4 scale.

Post by B Sharp »

I see that my last post was at the end of June so I am due an update. Plenty has happened with the build since then but not a lot of progress. I shall explain!
The wings and fuselage were covered with glass cloth and epoxy and all sanded back with 120 and 240 wet and dry. I was very happy with the finish as it was nice and smooth with very few blemishes. I applied a coat of white primer to everything and that’s when things started going wrong. The primer showed that although the surfaces felt smooth in fact the cloth weave was showing through. In addition there were masses of pin holes in the finish. Stupidly I applied a second coat of white primer and that didn’t improve matters one small bit. At this point I suspect that if Chris Williams is reading this he will be shaking his head and having a chuckle.
I bit the bullet, got out more 240 wet and dry and started rubbing down once again. When all the primer was gone I re-coated the whole airframe with another thin coat of epoxy followed by more rubbing back. This time when I resprayed the airframe with white primer there was no weave showing at all but there was still a lot of pin holes – out with the filler! There then followed several days of fill followed by sand back and gradually the number of pinholes was reduced. Finally I applied a further coat of primer followed by three coats of white gloss. By this time my right bicep was bulging and my shoulder aching.
In the last week or so I have got the ailerons fitted and servos installed. The elevator servo installed and a small moulded hatch created to cover the hole in the fin. It had to have a moulded bulge to clear the servo arm. The rudder was added and the servo installed in the fuselage. I have also created in interior for the cockpit including a natty little seat. This afternoon I have inserted the sockets for the wing retaining system and also the hinges for the undercarriage doors.
All photos below!
Brian.
Attachments
The fished painted wing with aileron attached.
The fished painted wing with aileron attached.
Aileron servo installation.
Aileron servo installation.
Servo well cover fitted.
Servo well cover fitted.
Elevator servo well cover.
Elevator servo well cover.
Rudder servo installed.
Rudder servo installed.
The cockpit installation.
The cockpit installation.
Wing retention system installed.
Wing retention system installed.
Undercart door hinges glued in place.
Undercart door hinges glued in place.

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Peter Balcombe
Posts: 1141
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Scratch built Pilatus B4 to 1/4 scale.

Post by Peter Balcombe »

Very clever fish in your part off the world Brian :lol:

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chris williams
Posts: 1164
Joined: 10 Mar 2015, 10:50
Location: Blandford Dorset

Re: Scratch built Pilatus B4 to 1/4 scale.

Post by chris williams »

(chuckle, chuckle)

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B Sharp
Posts: 736
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: Scratch built Pilatus B4 to 1/4 scale.

Post by B Sharp »

My Pilatus B4 build is now complete!!!
I have been working away quite steadily for the last few days on the installation of the undercarriage, the aerotow release and radio gear.
This morning I was able to assemble the model and check that everything waggles correctly and in the correct direction. The CG positions were recalculated and the model mounted on the balancer. I say positions (plural) as I always start with a “safe” slightly forward CG position for the first flights and then gradually move the CG rearwards until I get the aeroplane handling the way I want. I calculated the forward CG position using a static margin of 15% and a rearward CG position using a static margin of 10%. This placed the two CG locations 12mm apart on the wing root. A total of 473gm in the nose was required to achieve the forward CG position. However 130gm of lead can be removed incrementally to move the CG back to suit my flying taste. The total weight of the model came out at 5.20 kg – 11 lbs 6oz in old money.
I am rather pleased with the finished model and now only require a suitable day for the maiden flight.
Brian. :D :D :D :D :D
Attachments
The completed Pilatus B4.
The completed Pilatus B4.
The completed Pilatus B4.
The completed Pilatus B4.
Detail of the cockpit and canopy area.
Detail of the cockpit and canopy area.
Who's a happy bunny then?
Who's a happy bunny then?

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Cliff Evans
Posts: 262
Joined: 29 Dec 2019, 15:13
Location: Bristol
Contact:

Re: Scratch built Pilatus B4 to 1/4 scale.

Post by Cliff Evans »

Looks great Brian except, for the 4th pic! :lol: :lol: :lol: :lol:

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