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1/7 Scale Blackburn Buccaneer All Composite Scratch Build

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1/7 Scale Blackburn Buccaneer All Composite Scratch Build

Old 10-16-2018, 10:44 AM
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JSF-TC
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Default 1/7 Scale Blackburn Buccaneer All Composite Scratch Build

For years I have admired the all-composite models with their level of surface detail and scale fidelity, along with their ruggedness (no wrinkled film etc.) and have long harbored a desire to build an all-composite model, rather than just assemble one from a kit.

About each year, the itch would return and I'd research materials, processes and prospective models for a week or 2, only to convince myself that it was too much work, too much new stuff and not worth the effort.

Late last year I had 2 solid, good flying models (DerJet Hunter and an Ultra Flash) and I was starting to think about my next possible project. None of the available kits (ARF's/ PNP etc.) really jumped out at me as must-haves. Lots of nice models to choose from, but nothing that really got my attention. I was looking for scale subjects and something different, not another sport jet.

Well, around November 2017 I started thinking about scratch building again and all of a sudden the light bulb went off and I convinced myself that I was going to do it and I had decided on a model - not after careful down selection of various options, but a sudden decision.

I was going to build a Blackburn Buccaneer - Decision made.



Old 10-16-2018, 10:59 AM
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Call me crazy, but I hadn't done anything more advanced with composites than glass the occasional wing, and here I was contemplating building an entire model.

I made the decision to design the model in CAD and try to use technology as much as I could. I found a detailed 3D model (from a flight sim) which I downloaded and converted into Rhino, but it was a mesh based model, not one with smooth curves, so my first job was to try to build a viable CAD model. The more I looked at the more inaccurate the first 3D model was, so I ditched it and reverted back to the traditional 3 view drawings as a starting point.

First off was to decide on a scale, and after running some different numbers, I settled on 1/7 scale, which would result in a fuselage 108" long and a wingspan of 75.5". I am holding a working weight of around 50lb and power from 2 x 100N class engines.

Initially, multiple different 3-view drawings gave different outlines, but I eventually settled on one master 3-view as it scaled well with a profile photo.


I started with the tailplane and decided to make that all the way through the design/ plug/ mold/ finished part first before moving on to more complex shapes.

The tailplane cap gave me a good opportunity to start small as it was about 12" long. After laying out the design I used the 3D printer at my local library to print the part in ABS.

Coated in Duratec surfacing primer and sanded up through 1200grit, I was really happy with my first part. I was determined to capture surface detail on my model, so I engraved panel lines and fastener detail, again experimenting as I went.


Last edited by JSF-TC; 10-16-2018 at 04:24 PM.
Old 10-16-2018, 04:32 PM
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Initially I planned to use polyester resin for the molds and then epoxy for the flying parts.

I used 5mm foam poster board for my parting planes, hot glued together, designed in the same CAD system and laser cut for an accurate fit.

My first attempt I used Fibreglast water based release agent instead of the tried and trusted wax/ PVA.

I set off laying down a tooling gel coat and multiple layers of chopped strand mat, waiting expectantly to open it up. Shocked when I opened it up that the gel coat had cratered and wrinkled, making the mold useless.



Old 10-16-2018, 04:36 PM
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Luckily the plug was undamaged, so I tried again, and again, and again........

I must have made at least 3 plugs and 6 mold attempts using polyester, but every time it would wrinkle. Gel coat not thick enough, gel coat too think, needs to be sprayed not brushed. Every time a different reason could be found.

I also switched to wax/ PVA as a release agent which worked so much better than the water based system.

In desperation, I decided to switch to an epoxy based workflow for the mold. Ordering some epoxy surface coat, heavy glass cloth and epoxy resin I tried again and instant success!!!!






Last edited by JSF-TC; 10-16-2018 at 04:45 PM.
Old 10-16-2018, 04:42 PM
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Now it was time to build my first part. First attempt was reasonable, but showed that I really needed to vacuum bag the parts to force the cloth down into the mold corners.

So, more research and I ended up building a compressed air driven vacuum pump and buying more supplies; vacuum bags and clamps, breather cloth.

First vacuum bag attempt worked well and I ended up with a usable fin cap.

Old 10-16-2018, 05:02 PM
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Pressing on, I built the tailplane using a traditional built up sheeted structure then glassed. The center bullet fairing was 3D printed.

Primed and then coated with a couple of coats of Duratec, again sanded down up to 1200grit, I engraved the surface details. Part way through I had a change of plan and cut out the tailplane flaps to mold separately.

The Buccaneer has an all-moving tailplane with tailplane flaps which I planned to replicate. The tailplane flaps are used when the wing flaps are deployed.

For the surface detail I used a scriber for the straight lines and a selection of hypodermic needle tubes in a Dremel for the rivets. To get the even spacing, I laser cut a set of rivet templates out of 1/16" ply.

I soon switched from the scriber to an set of small engraving tools to give a square cut groove. 0.6mm wide seems to give a reasonable panel line representation.


Old 10-16-2018, 05:06 PM
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Next to mold were the tailplane flaps, being relatively small parts, another step in the learning process.




Last edited by JSF-TC; 10-16-2018 at 05:17 PM.
Old 10-16-2018, 05:13 PM
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I designed the tailplane flaps in CAD and laser cut them from ply, with balsa blocks for the hinge points.

Forgot to mention that I was now spraying the mold with 2-part car primer to produce pre-primed parts in an attempt to conserve the surface detail and not have them be lost in multiple layers of final priming. That worked well from the beginning.

I laid up the tailplane with a layer of 2oz and 4oz glass cloth with a carbon strip for the trailing edge, all vacuum bagged.

Bonding in the internal structure I used a thickened mixture of epoxy, applied using a small zip-lock bag with the corner cut off, much like a icing piping bag.

I was really happy how the final tailplane flaps turned out.



Old 10-16-2018, 05:33 PM
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Awesome, I wish I had the CAD skills to do what you are doing. Keep it up with the photos. Good work.

Subscribed!

Gary

Last edited by Viper1GJ; 10-16-2018 at 05:36 PM.
Old 10-16-2018, 07:45 PM
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Wait til you see some of the rest of the molds Paul has crafted. Outstanding project.
Old 10-16-2018, 10:47 PM
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That is fantastic work. So good to see someone designing and making rather than just installing servos into a ready built. I am also delighted by your choice of the Buccaneer, a much neglected subject but it's a plane that is much loved by us Brits.
Old 10-16-2018, 11:49 PM
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Great job! I´ve been waiting for the Buccaneer for a long time! Good luck!

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Old 10-17-2018, 01:45 AM
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NICE !!!

The Buccaneer is one of my favorite cold war planes, its another one of the era's unique looking aircraft.

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Old 10-17-2018, 03:17 AM
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Thanks for the comments.

Gary - My CAD skills are entirely self taught and would probably make any self-respecting CAD professional cringe at my ham-fisted use of it, but I get there in the end, partially being stubborn and knowing that what I want it to do should be possible. Having and end-goal in mind certainly helps rather that just drawing something for learning sake.

Harry - I grew up in the UK and moved the the US nearly 20 years ago. Still have a soft spot for the UK aircraft and can remember seeing them all at the airshows during the 80's and 90's. Lightnings, Buccaneers, Phantoms, Harriers, Jaguars, Canberras, sadly now all gone.
Old 10-17-2018, 05:56 AM
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Looking great Paul! I can't wait to see it in the air. Go man GO!!!

Woody
Old 10-17-2018, 06:30 AM
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Very impressive work!
Old 10-17-2018, 12:03 PM
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Hey Paul,

Your CAD skills are pretty good,

The future of modeling might be with the people who can chop a model and send it to print seeing ... QUALITY ... nearly 2 foot print beds are around 600 dollars now

What 3d printer are you using at the library?

The Wanhao 3D printer has a 1 foot cube print space for around 500 -https://www.3dprintersonlinestore.com/3d-printers/wanhao-3d

A guy has printed 95% of a 1/6:5 L-39 with it, even printed the fan and wheels and landing gear with the Wanhao ABS printer. - https://www.rcgroups.com/forums/show...6-5-scale-L-39
Old 10-17-2018, 01:23 PM
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The Benbrook library has 2 PolyPrinter 229 3D printers, but I recently purchased a Prusa v3 printer for my own personal use, as I was starting to print some very large, multi-day print run pieces - more details to come soon.

I was surprised how (relatively) cheap the Prusa kit was and it only took me a couple of days to assemble.

Last Christmas I bought a 400mm x 600mm 50W laser cutter from Amazon - I wouldn't have been able to do most of what I've been doing without it to be honest. Generating the foam-board mold construction parting planes is simple and repeatable, plus they fit the parts like a glove with minimal wax gap filling. It has earned its keep cutting the ply and foam for the fuselage plug too.

I love the ability to work in the digital workflow direct from CAD to either the laser cutter or 3D printer - parts fit perfectly without any adjustments (assuming the design works in the first place).

Paul

Last edited by JSF-TC; 10-17-2018 at 01:31 PM.
Old 10-17-2018, 03:28 PM
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Paul,
Congrats on self taught CAD skills, I tried and failed, it was more that I could figure out during my airline trip hotel layovers. I had a chance to fly with the RAF Buccaneers in the first F-16 Maple Flag exercise in Cold Lake, CA. It was 1981 I think. Those guys flew lower than I had ever seen. I mean they were low! They were a great bunch of guys.
Gary
Old 10-17-2018, 04:04 PM
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Next up was molding the all moving tailplane plug, my most complex part so far.

Parting plane again was made from foam poster board. CAD representation shown along with the actual part.



Old 10-17-2018, 04:08 PM
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More photos of the tailplane mold construction. Microballoon filled epoxy was used to fill in some of the sharper corners on the mold before covering with glass cloth.




Old 10-17-2018, 04:11 PM
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I had to make the second mold side in 2 pieces because my parting plane was inadvertently offset from the centerline, so I would have an undercut trapping the part.

The recesses in the tailplane plug for the pivot/ mounting hardware and the servo hatches can be seen.

Old 10-17-2018, 04:17 PM
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With the molds successfully made, nexy was making the actual tailplane. Skins were made as the flaps with 2oz and 4oz cloth and a carbon tape along the main spar.

Sub-structure was made from 5-ply aircraft ply. I molded a c-section strip around the leading edge of the plug to form a larger bonding area for the upper and lower skins. I don't want the risk of the leading edge splitting and exploding the tailplane in flight.

Matching hinge pin holes were cut in the rear spar to align with the tailplane flap hinge points.







Old 10-17-2018, 04:23 PM
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The finished tailplane with flaps and cap positioned for a morale boosting photo.

I had some difficulty removing the peel-ply from one of the skins, due I think to excess epoxy in the sharp corners. As I have improved my technique, I may re-make the tailplane at a later time, but some filler and primer should cover the defects on this one.

Old 10-17-2018, 05:10 PM
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Awesome, I love following your process. Thanks.
Gary

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