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Oct 15, 2019, 10:45 PM
Summit Model Aeronautics
Steve85's Avatar
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I keep finding things to do that allow me to put off installing gear and wiring, like starting to carve the plug for the Bolly’s distinctive canopy and navigator’s greenhouse. It seems the original Mark I Blenheim had a completely different cockpit greenhouse, and the next production version, the Mk IV, introduced a longer, more streamlined nose with more space for the previously neglected navigator. Unfortunately, the longer glazed nose obstructed the pilot’s forward view during take-off and landing, so Bristol scooped out the left-hand side of the top of the nose to give the pilot a better view forward. The Canadian-built Bolingbroke was essentially a Blenheim Mk IV, and it got the unique asymmetrical forward glazing too.

Unique and asymmetrical sounds cool, until you decide to mold one. After looking at a bunch of photos of the Bolly’s nose, I decided that the best way to proceed was to mimic the Bristol designers and start with a symmetrical plug and then “scoop” the left side to shape. Having tried a number of different vacuum forming plug materials, I opted for balsa for a good balance of ease of shaping with durability. I had a nice block of straight-grained 10 pound balsa, and an hour of measuring, drawing and careful sawing turned it into an square-sided blank that fit on the fuselage for detailed shaping.

Steve
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Oct 16, 2019, 09:40 PM
Summit Model Aeronautics
Steve85's Avatar
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With the balsa canopy plug rough-shaped into planes and simple curves, it was time to jump into the deep end and start carving some compound curves. I added a few guide lines to keep me onside, and started by rough rounding the top of the forward part of the nose. Next up was cutting the windshield panels and then carefully blending in the top of the navigator's forward canopy. Having got that done without digging a bunch of divots into the plug, I put it away until tomorrow when I'll start fresh and scoop out the left side of the nose.

Steve
Oct 17, 2019, 03:21 AM
Registered User
balticS2's Avatar
Very nice illustration of deconstructing a complex shape. This is going to be a huge bonus if you get round to kitting these.

Alec
Oct 17, 2019, 06:41 AM
So I'M meant to be in control?
Colonel Blink's Avatar
....and I often wondered by the port side was concave!!!
Oct 17, 2019, 10:27 AM
Gorilla glue rocks
Spit100's Avatar
I just like all the balsa chips on the floor and the wine glass in the background. Nice work!

Jon
Oct 17, 2019, 11:39 AM
Registered User
AntiArf's Avatar
Quote:
Originally Posted by Colonel Blink
....and I often wondered by the port side was concave!!!
Insight. They knew it would make it more complicated for modelers sculpting molds in the future.
Seriously real nose glass will really make the model, and is yet another reason the subject isn't modeled much. Fake windows just don't get it for subjects where the nose glass is a major detail area.
Oct 17, 2019, 04:32 PM
Summit Model Aeronautics
Steve85's Avatar
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Thanks, guys. Alec, "deconstruction" is a very apt description of my mental process as I tried to figure out the best (any?) way to approximate the Bolly's nose shape. Colonel, I confess to having taken advanced technical training in the UK while I was still in the service, and I continue to be amazed by the sheer inventiveness of that most fascinating of oxymorons - "British engineering"... AntiArf, I couldn't have built the model with painted on windows, that just wouldn't have been right. Of course, assuming I can pull a decent canopy from this plug, I'm going to have to make an effort on the cockpit interior too. No good deed...And Jon, while the carving process didn't need any lubrication, the carver sure did...

Before going any further, I have to caveat the effort by saying that I'm building a sport scale model, and that while I have quite a bit of documentation (and access to a full-scale restoration effort), no micrometers or laser imaging radars will be used in the fabrication of this canopy. TLAR will be my motto.

That said, I've posted a couple of photos of The Real Thing that I've found quite helpful. The "work in progress" photos are from the ongoing Bolly restoration at the Greenwood Military Aviation Museum in Nova Scotia, but I've forgotten where I found the excellent photo of a fully restored Mk IV forward fuselage. Having studied my references carefully over a glass of suitable lubricant, I carefully attacked the balsa plug with my cordless drill and sanding drum attachment. I'm quite happy with the result so far, and I'll probably fiddle with it a little more until it looks about right, but the next step will be to add some more balsa infill to the adjacent fuselage sections and then tackle the very front end of the fuselage.

Steve
Last edited by Steve85; Oct 17, 2019 at 08:56 PM.
Oct 18, 2019, 01:43 AM
So I'M meant to be in control?
Colonel Blink's Avatar
Wow! As we used to say when I was an apprentice - 'Bloody good work, fella!'
Oct 20, 2019, 10:25 PM
Summit Model Aeronautics
Steve85's Avatar
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Thanks, Colonel! I can only ponder and plan for so long before I get the urge to just pick up a knife or a sanding block and see what comes out!

When I drew up the plans a few years back, I confess I didn't think through the details of attaching and fairing in the canopy greenhouse to the rest of the fuselage. Of course, it would be easy enough to simply glue the canopy edges to the covered formers and stringers of the fuselage, Guillow's style, and there would be nothing wrong with that. Having watched modellers like Fuzz St. Martin, Longhorne and AntiArf neatly fair canopies into their fuselages, however, I decided I'd give it a try on my Bolly. This meant quite a bit more inset sheeting on the nose, starting with the sections of the fuselage adjacent to the eventual canopy. I needed to add the rough blank for the forward nose before I could start filling in the lower forward fuselage, and ultimately decided that I might as well fill in the entire lower nose back to the bomb bay hatch, adding strength in an area where extra weight won't exact a penalty. This was where a bit more foresight on my part would have been helpful, since I wouldn't have scalloped the middle former.... I'll have to fill the resulting crack with some spackle.

Tomorrow I'll rough sand the whole shebang and that classic Bolly nose should emerge.

Steve
Oct 21, 2019, 12:25 AM
Res Ipsa Aviatur
Longhorne's Avatar
Heya, Steve--the Bolly looks great! I have a soft spot for the Bristol bombers. I roughed out the CAD shape for a Beaufort a few years ago and got the chance to photograph the one at the RAF museum in London. Some day

I wouldn't sweat that pesky scalloped former. The gap is so small that you could cover right over it. Or fill it as you have planned.

Paul
Oct 21, 2019, 01:20 AM
Big gov never Works
St. Martin's Avatar
Quote:
since I wouldn't have scalloped the middle former.... I'll have to fill the resulting crack with some spackle.
Heck..I still do it! I usually strip of a piece balsa the width of the stringer space, bulkhead thickness, and round the end of the strip to match the kohllop(the proper name). Med CA it to the bulkhead and trim/sand. Viola'!

Fuzz
Nov 09, 2019, 05:56 PM
Summit Model Aeronautics
Steve85's Avatar
Thread OP
Life has allowed only a little time for modelling during the past couple of weeks, but I've whittled away (a Dad pun, my boys would say...) at the Bolly as time has permitted. The work has been gratifying, but not quite spectacular; infilling, sanding, spackling, sanding some more, lacquering, repeating as necessary. The forward fuselage (less the plug) is now pretty much ready for covering, and I've moved to infilling and prepping the seat of the dorsal ("mid-upper" in British parlance) turret and the wing fillet. More photos to come!

Steve
Nov 09, 2019, 09:00 PM
Big gov never Works
St. Martin's Avatar
Hi Steve

That has a nice vertical outline. Kind of D'Havillandish. I have built planes, because of the vertical shape alone. ahhhh...Watco...is that gloss?

Fuzz
Nov 09, 2019, 10:51 PM
Summit Model Aeronautics
Steve85's Avatar
Thread OP
Hey Fuzz,

Yeah, now that you point it out, the tail does look like something Geoffrey de Havilland might have drawn. Maybe British aircraft designers in the '30s all used the same French curves... The Watco lacquer is satin, just like you recommend.

As mentioned in my earlier post, the dorsal turret seat is now prepped, as are the bases for the wing fillet extensions behind the wing trailing edge. I've had good results building wing fillets out of pink foam like I did some years back for a Guillow's Spitfire, but I'm leaning towards using lacquer while covering, so foam is ruled out this time around. I decided to try the built-up balsa sheet wing fillets that others have used, but didn't pay enough attention to the actual shape of the fillets on the real Blenheim before getting started. The resulting fillet was much larger than it needed to be, so I started over on the other side of the fuselage. This time I got a result much closer to scale, so all I need to do now is sand and fill, and then do it again on the left hand side (after ripping out the first attempt).

Steve
Nov 10, 2019, 03:16 AM
Father by day, hacker by night
JornWildt's Avatar
Lovely set of stringens


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