Short S23 Empire

[AdrianMF]

Hi All,

 

I started this in the Flying Boats and Float Planes II GB and didn't finish it, so I've brought it across here. The full story is here and there's a summary below.

 

The S23 C-Class Empire Boat was designed in the 1930s in response to an Imperial Airways requirement for an aircraft to transport airmail and passengers across the far-flung British Empire. At the time a long flight consisted of a series of relatively short legs, and along the routes there were neither runways nor infrastructure to support land planes, so seaplanes were preferred because they could use existing facilities in harbours. Shorts decided to build a modern monoplane, it is said, after watching the DC-2 and DH-88 in the McRobertson Air Race to Australia.

 

Shorts produced a number of related designs: the S30 (re-engined Empire Boat); the Maia (a design based on the Empire Boat to launch the Mercury sea plane); the S26 G-Class (a larger version of the Empire) and the S25 Sunderland military flying boat. The Sunderland had the similar wings and tail surfaces to the Empire, so in preparation for this build I hunted down a cheap "spares or repairs" kit on Ebay:

 

The tail surfaces were cut down a tad to represent the S23 tail and the mounting structures were borrowed too:

 

The engines from the Airfix Sunderland are of their time (1958) and took a lot of work (and a cast of a FROG Blenheim engine) to knock into shape. I wasn't fancying doing four of them! At SMW, Wonderland Models were selling scrapped Italeri sprue trees in a big rummage box - quite by chance I found and bought a couple of Sunderland sprues with modern engines and other details for £4. Still can't believe my luck! You can see the original and modified Airfix cowlings at the top:

 

I briefly thought about modifying the Sunderland fuselage to make the S23 but, like the man said when asked for directions in Ireland, "I wouldn't start from here".  So, out with the one set of trustworthy plans and start cutting plastic:

 

Mark the bulkhead edges with a sharpie, stick them on the profile and fill with balsa:

 

Then start filling it out to shape with two part car body filler:

 

And get sanding!

 

I really hadn't thought about what to do after that. So I decided to use the form as a male vacform mould, this being the simplest approach. My teeny weeny canopy vacform box (about 3" square) wasn't going to hack it, so I placed an order for some A3 1mm/40 thou card and built a vacform box to match - 280 1.5 mm holes and lots of internal struts to stop the box sucking in:

 

I drilled some holes in the valleys and inside corners around the float surfaces on the mould to let the plastic suck into the hollows, and on the later attempts, oiling the mould with peanut oil really helped to reduce mould damage and ease separation. Staples and heatproof tape to hold the plastic in place and lots of attempts of varying levels of success (well 5 actually because that's how many sheets of A3 1mm plastic I bought):

 

So, that's the work to date.

 

Since then I've been doing bulkheads:

 

I am making this build up as I go along - I might do windows and doors next, or wing spars, or cockpit, or something else...

 

Thanks for looking,

Adrian

 

 

[Greg Law]

Pleased to see this here Adrian.  Good luck with it. It is an epic project. 

[Hamden]

 

Interesting project, thanks for showing the process of constructing the mould master.

Will follow along and learn more if you don't mind?

 

                Roger

[Gorby]

I fully intend to build myself a vac-form device this year so it's been very interesting reading through your post on this remarkable project.

How did you heat such a large sheet of plastic?

[Jonners]

Keep it up, Adrian; it's looking pretty epic! I especially like the philosophy of making it up as you go along. Might be doing some of that myself...

Jon

[bigbadbadge]

Hi Adrian

Good to see this brilliant build carry on , great work on the fuselage and bulkheads . Can't wait to see this develope.  

 

[Unfinished project]

I will be following this with great interest. The Mercury and Mia used to leave from The River Tay at my home town of Dundee

[woody37]

That’s amazing Adrian, looking forwards to following your progress, this takes home vac forming to a new level

 

 

[Pin]

Very cool, Adrian.

Ever considered selling a conversion kit? Some people may be interested

[Ex-FAAWAFU]

Chuffed to see this one moving over here; it was the main (& eventually only) reason I kept going back to the GB pages

[Pin]

Another concern - if you do a "father" mould, do you consider the thickness of the plastic and thermal shrinking? If your master is to the scale your mould will be slightly (or not slightly) off 

[AdrianMF]

4 hours ago, Hamden said:

Will follow along and learn more if you don't mind?

I've heard it said that learning by other people's mistakes is the best way!

 

4 hours ago, Gorby said:

How did you heat such a large sheet of plastic?

I use a paint stripping heat gun for canopies but that is nowhere near powerful or uniform enough for large areas (A3 is 420mm x 297mm). My domestic oven grill gets hot but it still isn't very uniform, so I have been warming the sheets in the oven at 120 deg C (fan) to get them almost up to temperature, then I switch to the grill for the last 30 seconds to get it properly floppy.

 

It's all a bit of a panic really, and timing is me counting while switching on the vacuum cleaner and getting ready with oven gloves etc. the stripey moulding is where I got it very wrong and the plastic sagged down onto the oven shelf! The plastic does need to be hot because it has to go down all the way to the bottom of the "top" side, which is a sheer wall rising from the vacuum bed. My main problems have been: webbing along the top seam (plastic not hot enough to get pulled down all the way); and mould damage caused by plastic getting too hot (definitely alleviated and possibly cured by a coat of groundnut oil). So I'm stuck between a rock and a hard place in that respect. Given that I've only had five goes at it, I don't have a foolproof recipe (yet?).

 

4 hours ago, Jonners said:

making it up as you go along

I was doing that on my Airfrog Beaufort project, so I'm not too worried (yet). Glad to see Airfix took the hint.

 

4 hours ago, bigbadbadge said:

bulkheads

With all those arched doorways I was having flashbacks to helping my daughter with some school castle project...

 

3 hours ago, Unfinished project said:

The Mercury and Mia used to leave from The River Tay at my home town of Dundee

I didn't realise - I always assumed that it would have been Southampton. That must have been a sight!

 

3 hours ago, woody37 said:

takes home vac forming to a new level

er, Mrs MF has said that to me. Frequently. And not in a good way.

 

3 hours ago, Pin said:

Ever considered selling a conversion kit

Not sure how durable the master is going to be. If I get further down the line with this (so I can see if it works or not) I might bash out a few more just to see if I can get the cooking time right. But...

 

I am always happy to post the odd spare part to fellow modellers, and other people have been similarly generous to me. However, doing something this big could get non-trivial quickly in terms of time, attention, postage and materials, and if I start asking for money that means I have customers with expectations (possibly higher ones than I can fulfil). So I need to make sure I don't turn an enjoyable hobby into bad industry. Let's see if I'm barking up the right tree first. 

 

2 hours ago, Ex-FAAWAFU said:

GB pages

I have really enjoyed the GBs I've participated in this year - I guess it depends on whether the theme resonates. Maybe if we have an "Unjustifiably Unloved Unwinged Things" GB you would be keener

 

1 hour ago, Pin said:

do you consider the thickness of the plastic and thermal shrinking? If your master is to the scale your mould will be slightly (or not slightly) off 

I did not. At one point I naively thought I could build a female mould for it, but then reality set in. If I measure my model against the plans, the width is 43.5mm against 10ft in reality (42.333mm, plan is dead on), and the height at the deepest part is 70mm, against 69mm on the plan. I'm not even thinking about the length yet because I will be re-shaping the tail from a blob to a set of finely-pointed fin and tailplane fairings. So it's about 1mm over scale. That's before sanding it down (there will be a lot of sanding) and adding a few coats of primer (there will be a lot of that too). I don't mind it being 1mm over in width and height. I can't see the difference when I look at it, and I intend to display it floating in the water, so it will be hard to judge the height anyway. For me, there are more important visual issues, like restoring the crisp edge between hull and planing bottom, which is rounded out because of the vacforming process.

 

Which comes back to your conversion kit question. I know my current customer (me) doesn't care about 1mm either way. And if I'm sending out a spare I can ask the recipient to use it or bin it with no obligation either way. But supply for money changes everything. I don't know.

 

Regards,

Adrian

 

 

[Ex-FAAWAFU]

1 minute ago, AdrianMF said:

I have really enjoyed the GBs I've participated in this year - I guess it depends on whether the theme resonates. Maybe if we have an "Unjustifiably Unloved Unwinged Things" GB you would be keener

I have nothing against GBs as a concept - it’s just that at present my rate of building is glacial, a likely to remain so until retirement.  The concept of modelling vs a deadline would probably tip me over the edge completely!

 

There was a Sea King STGB at one point, and I didn’t even partake in that: QED!

[hendie]

3 hours ago, Ex-FAAWAFU said:

Chuffed to see this one moving over here; it was the main (& eventually only) reason I kept going back to the GB pages

 

likewise.  I'm always a sucker for a how on earth is this going to turn out build - the more scratching the better I say.

 

Adrian - I've caught a few builds of yours over the years... you don't like doing things easy do you?

 

 

1 hour ago, Ex-FAAWAFU said:

The concept of modelling vs a deadline would probably tip me over the edge completely!

 

not unless there was a 10 year deadline - and even then I'd probably still be pushing it!

 

 

Have you thought of doing a multimedia build ?  You could capture that bottom form of the boat hull and sharp edges easily with resin and it could provide a nice solid base to attach the fuselage sides to and build from.

[tomprobert]

This is such a great project - I’m glad we can continue to follow your progress. 
 

Tom

[AdrianMF]

55 minutes ago, hendie said:

you don't like doing things easy do you

Well I like to build a few "good" kits a year (this year the Revell X-15, new Airfix Spitfire 1 and Tomahawk) but frankly it's just sticking bits together after a while, so doing them as blitz builds adds a bit more enjoyment. I like a bit more fettling than that, but not so much that I want to start with a block of balsa for everything. A good build for me starts off scary and ends up finished!

 

I'm going to glue some stretched sprue runner round the edges and blend it in with some solvent-y filler like Humbrol before I start sanding the exterior, so hopefully that will give me my sharp edges back.

 

Regards,

Adrian

[fjaweijfopi4j48]

9 hours ago, AdrianMF said:

I did not. At one point I naively thought I could build a female mould for it, but then reality set in. If I measure my model against the plans, the width is 43.5mm against 10ft in reality (42.333mm, plan is dead on), and the height at the deepest part is 70mm, against 69mm on the plan. I'm not even thinking about the length yet because I will be re-shaping the tail from a blob to a set of finely-pointed fin and tailplane fairings. So it's about 1mm over scale. That's before sanding it down (there will be a lot of sanding) and adding a few coats of primer (there will be a lot of that too). I don't mind it being 1mm over in width and height. I can't see the difference when I look at it, and I intend to display it floating in the water, so it will be hard to judge the height anyway. For me, there are more important visual issues, like restoring the crisp edge between hull and planing bottom, which is rounded out because of the vacforming process.

I am absolutely with you on this.

The difference can't be appreciated at all.

No kit I have or ever had is spot on. And then there is the issue of plan accuracy, sources disagreement, printer distortion, humidity, etc.

The difference is absolutely negligible, and your work is monumental, fantastic, and truly impressive.

Please keep delighting us with this splendid job.

Cheers

[Bandsaw Steve]

Nice! Have only just discovered this and am impressed with your ambition. Great subject!

[Bandsaw Steve]

Oh yeah - where did those lovely plans come from?

[Pin]

7 minutes ago, Bandsaw Steve said:

Oh yeah - where did those lovely plans come from?

Second to this question. Any chance there is Maia as well? 

[AdrianMF]

2 hours ago, Pin said:

where did those lovely plans come from?

There is a man called Brian Cassidy who has done an awful lot of research on the Empire Boats. He was involved in pulling together a set of plans from the fragments of information left after Shorts decided to dispose of their design archive in the 1960s or 70s. There is a copy of the plans available for download on the site http://www.seawings.co.uk/, which is a very interesting and useful site. 

 

The Harborough publishing company (of Aircraft of the Fighting Powers fame) drew up many plans in 1/72, including one of Maia, of which I have an electronic copy, but I'm not sure how accurate it is. I have never seen a 1/72 plan of the G Class. Not sure offhand if there are any plans in AotFP.

 

I imagine there must be typically tiny plans of Maia/Mercury and the G Class in the Putnam volume on Short Bros aircraft, but they are probably too small to be useful, and Brian Cassidy did point out some errors in the Empire Boat plans in that book.

 

I will have a look in my Putnams and AotFPs when I get home.

 

Regards,

Adrian

[Bandsaw Steve]

Thanks Adrian. 
 

Well done Mr Cassidy. What a great shame the original plans were destroyed.

 

 

 

 

[AdrianMF]

One of my colleagues went to Portugal for Christmas and brought back some fancy chocolates. The box is perfectly clear food grade polystyrene about 1mm thick. That’s the windows sorted:

 

 

 

[spaddad]

Adopt, adapt & improve.

[AdrianMF]

FWIW, the Putnams books (Shorts and British Seaplanes) have tiny line drawings of C-Class, G-Class and Mercury/Maia. There is nothing in any of the AotFP volumes.

 

Janes World Aircraft 1941 has some tiny black silhouette drawings of the C-Class.

 

One of the huge downloads in http://therealmidori.com/Multiviews/ has a plan of the Maia in it which looks to be copied from a 1/72 or 1/144 Harborough-style drawing 

 

Regards,

Adrian