de Havilland DH.50 - RAAF - 3D Printed Model Test Build

[Ed Russell]

The De Havilland DH.50 was built in relatively small numbers but there is an interesting variety of engine types and finishes. There are a couple of scratch-built efforts I have seen but no conversion, let alone a full kit is available.

Hobartville Hobbies have set out to remedy this deficiency with a 3D printed kit. I have one here to build and propose to do it as a RAAF floatplane.

 

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It has a bit of historical significance as in 1926, it was used in the first international flight made by the RAAF. The Chief of the Air Staff, Group Captain Richard Williams, and two crew members undertook a three-month, 10,000 mile round trip from their base at Point Cook in Victoria to the Pacific Islands.

 

My experience of 3D kits is limited but I have managed one reasonably successfully. As a result I have had some input into the design of this kit. Being a pre-production kit I will have to make up some of the steps as I go. Let the principle be - Let me screw up so you don’t!

 

 

There is quite a bit of DH.50 information available. There are threads here on BM, my Red Roo colleagues provided pictures and articles as did Juanita Franzi @Juanita of Aero Illustrations, which facilitated development of the kit.

 

The kit is very nicely injected with no scaffolding. There are a few spikes and divots as a result of the 3D process but no more imperfections than on a mid-range resin kit. There is no visible striation except under high magnification. The parts fir together with great precision.

 

 

Being a typical modeller I cannot resist tinkering with any kit, no matter how good, so I added a couple of extras. Maybe something will be seen though the rather slitty windows (probably not) but let’s add a couple of seats. The DH.50 was a four passenger plane but I assume the international and later survey flights would mean extra equipment might be needed. I added some boxes forward of the seats, all of which sit on the (invisible) floor. There is a semi-cutaway of G-EBFO which, while being a special DH.50J does give an idea of the arrangement.

 

 

The seats and boxes are almost in half-relief but they will give the right impression.

 

 

The kit cockpit detail has been added and an instrument panel crafted up – the kit will probably include a decal.

 

 

 

That should be enough to close the fuselage up. Better think about those windows first.

[Ed Russell]

The final form of the kit will probably come with a clear section for the passenger windows. In lieu of this perhaps the easiest way to do it is to make some frames and fill them with Kristal-Kleer. They are made of very thin styrene strip and fir into the recesses around the windows. As you can't mask them I will leave them off until much later in the asembly. Of course they will be cleaned up and painted silver before installation.

 

 

The wings are pretty good. They are scale thickness and, after much experimentation, they don't have the starved cow look of earlier efforts (and many present day injection moulded kits!) with the ribs protruding. In fact they are commendably restrained. The wings do have a few divots in the trailing edge and a gap at the end of the ailerons.

 

 

These defects can be remedied with gap-filling cyano and plastic shims. Note the faint striations in this very high magnification picture. They are invisible in real life and even more so after painting.

 

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[Ed Russell]

I have been making slow progress with this as other things in life get in the way. The wings have been cleaned up and are ready to attach. This picture shows some of the minor repair work needed.

The main problems are the gaps between the main wing and aileron but they are easily filled with plastic strip and finished off with some putty. I used Tamiya grey putty for some parts. Perfect Plastic Putty for fine gaps and Mr Surfacer as a finish. it sounds harder than it is.

The fuselage presented a problem unique to 3D printed kits. The join was near perfect but there was a little bit of cyano squeezed out. Very fine sanding removed it but caused almost microscopic delamination of a small part of the surface. All you can do is fill and sand  like any resin kit.

Here we have covered most of it but a little more sanding is needed

Now we have it pretty nearly right

It's worth putting in some effort as the finish will be polished aluminium and aluminium dope.

[Ed Russell]

The wings are now attached. There are substantial locating tabs which make it easy. As someone used to vacform and limited run injection kits, this is a luxury. it gets better though, as there are locating holes for spars in the upper wings - see later.

The wing has a 3 degree dihedral, which is accomplished with a 4.5mm riser block at the wingtip, made from a wooden Camembert box -  I will see if a couple of these can be included in the kit as i have plenty in my miscellaneous wood bin.

 

 

The tailpanes are later attached using a Lego jig. These fit nicely although you do need to drill out the holes for the tail as they are certain to be occluded with cyano. it's not difficult and the tail fits nicely.

 

I like to have propellers removable (or at least movable) to cope with transport. They are often vulnerable to damage if fixed. The kit comes with a stub on the radiator (lower one) and a hole in the propeller. I drilled out the radiator and insrted a piece of 1.6mm ID brass tubing and added a 1.5mm section of plastic rod to the prop.

 

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[bigbadbadge]

This certainly looks interesting and is going together well. Great work and a real honour to be involved like that too.

Looking good .

Chris

[perdu]

What Chris says and a rather wonderful start to the life of this kit.

 

Wondering if using UV setting resin might not be quite useful here as a repairing filler.

 

Anyroadup, watching this un.

[Brandy]

Looking good, and I'm happy to see the improvement in the wings over the A-W FK3.

You could also try resin as the glue, and cure it with a light pen. That is how @TheBaron has done it done on his Sea Vixens and it appears to work very well.

 

Ian

[Ed Russell]

On 4/9/2022 at 10:57 PM, perdu said:

using UV setting resin might not be quite useful here as a repairing filler.

 

On 4/10/2022 at 12:13 AM, Brandy said:

resin as the glue, and cure it with a light pen

Excellent idea and I do have this kind of glue. I will do a test shot and report back. In the picture is the wood I used to make the spacers. Of course anything 4.5mm will do the job.

 

[Andwil]

1 hour ago, Ed Russell said:

In the picture is the wood I used to make the spacers. Of course anything 4.5mm will do the job.

Good excuse for a King Island Camembert 

 

AW

[Bell209]

Very nice work, Ed. Should really look the goods when done!

[stevehnz]

On 4/9/2022 at 11:30 AM, Ed Russell said:

made from a wooden Camembert box

Oooh, that sounds a bit posh, I can only afford common or garden foil wrapped C'bert.   I did think it was a fine line of BS, the blurb on the box top, I'd buy one just for a copy of that.  

I do like the idea of a DH.50 that is not too labour intensive so I'm following this with ulterior motive, one with a wheeled U/C & some Kiwi decals would be right up my alley street. I could probably manage the decals.  

Steve.

 

[Ed Russell]

35 minutes ago, stevehnz said:

I'd buy one just for a copy of that.  

Haha - I'll make sure a full lid is in your DH.50 which will indeed have a wheeled option - Qantas and RFDS to start.

What does a Kiwi one look like? It could be an option for future kits.

 

Edit - There's one pictured here

https://www.britmodeller.com/forums/index.php?/topic/235048571-dh50-info/

Perhaps @Anthony in NZ or @k5054nz might have more. Or @TonyTiger66 or @VH-USB who contributed to the thread?

 

[Ed Russell]

The upper wings are an advance on previous HH kits. They are at scale thickness for a DH.50 and thus don't bend like the scale thickness FK.3 ones. The centre section has through holes for spars to fit into the wings which are pre-drilled, or at least marked for you. The 3D printing process does this with great accuracy. Silly me forgot to photgraph the ones I used but here's the top and bootom views of an earlier (too thin) iteration to illustrate the point.

 

 

 

The same 4.5 mm risers are used to set the wing dihedral and it is allowed to set until it is properly hardened.

 

 

The steel straight edge is used to make sure all three pieces are in a line.

 

 

[Derek_B]

Looking good Ed. I recently "blogged" about the three Western Australian Airways DH.50s which went in search of the Southern Cross in 1929 on the AHSA Facebook group. This looks like it will come together nicely.

Edited April 13, 2022 by Derek_B

[Ed Russell]

Turning back to the fuselage, it was given a light coat of Mr Surfacer 1500 to try and highlght imperfections.

 

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It looks a bit crappy but I was hesitant to spray it much heavier for rear of losing surface detail. After another light coat it looks better.

 

 

This DH.50 is in aluminium dope and looks fairly uniform in finish so not much scope for lots of different aluminium shades. Maybe the plywood fuselage, metal panels and fabric covering can be a little different but not much.

[k5054nz]

On 4/11/2022 at 8:08 PM, Ed Russell said:

What does a Kiwi one look like?

Something like this! It's an easy choice as we only had the one DH.50A, serial 135 of the New Zealand Permanent Air Force.

Note the above picture is my home airfield so building "135" is a no-brainer for me!

Edited April 18, 2022 by k5054nz

[stevehnz]

Super photos there Zac, most of them new to me as well. Thanks.

What is the in front of the hanger. Moth or Avian, or something else.?

Steve.

[bigbadbadge]

Looking forward to seeing the silver shades go on , that should look awesome. 

Lovely photos too @k5054nz.

Chris

[ianwau]

Following with interest Ed.  I have a dormant 1:48 scratchbuild DH50 in the shelf-queen section.  This might just give me the inspiration to resume...

[Ed Russell]

The first light coat of Model Master Aluminium showed lots of imperfections to fix. Sand, fill. repeat, repeat, repeat. It still needs more but it's looking better.

 

 

Those trailing edge divots are a lot harder to fix than I thought they would be. It's mainly getting the curvature right with a half-round file.

[Ed Russell]

On 4/18/2022 at 10:44 AM, k5054nz said:

Something like this! It's an easy choice as we only had the one DH.50A, serial 135 of the New Zealand Permanent Air Force.

 

Note the above picture is my home airfield so building "135" is a no-brainer for me!

I looks as though 135 was the constructors number and it was also used as a serial although not displayed on the aircraft. The "23" refers to something but we don't know what!

Info from the RNZAF Museum.

[k5054nz]

On 4/18/2022 at 5:10 PM, stevehnz said:

What is the in front of the hangar. Moth or Avian, or something else.?

I believe there were more than a dozen Moths present for the opening and possibly one Avian, along with the Cierva C.19 ZK-ACL, one of the local Avro 504Ks, and from the NZPAF an F.2B and up to four Moths (as well as the DH.50A). I'm only going by a very small number of photos and hoping to unearth more.

Edited April 24, 2022 by k5054nz

[Ed Russell]

The upper wing is also at a 3 degree angle and has similar divots but rather fewer.

 

 

We will try and minimise these in the production kit and also give you  a couple of spacers to set the dihedral.

 

 

They look a bit agricultural but will do the job.

[Ray S]

This is looking very good indeed, and will hopefully be a success for Hobartville Hobbies! They seem to be producing a good selection of subjects.

 

Cheers, and all the best for the rest of this build,

 

Ray

[Ed Russell]

The small parts are in the process of being painted. Very little clean-up, if any at all, is required. The struts are carefully packeged as the leading and trailing ones are different lengths. I have put one set of each per wooden painting block. Leading, trailing and float struts.

 

 

These kits are now commercially available.

https://www.redroomodels.com/product/de-havilland-dh-50a-1-72-scale/

If it says "Out of Stock" do not despair, as we will replenish the supply at regular intervals.