Tamiya 1:72 Mosquito FB Mk.VI

Tamiya 1:72 Mosquito FB Mk.VI

Author
Discussion

ftypical

457 posts

117 months

Saturday 6th June 2015
quotequote all
A wooden Tornado? Interesting... smile

dr_gn

Original Poster:

16,140 posts

183 months

Saturday 6th June 2015
quotequote all
ftypical said:
A wooden Tornado? Interesting... smile
Don't ask why they ended up as spares and why they've had the fronts sawn off. My social worker says if anyone brings the subject up it could put me back months.

Lotus 50

1,009 posts

164 months

Sunday 7th June 2015
quotequote all
This is going to look amazing when finished, but, at risk of being pedantic (well, OK not "at risk" just being pedantic!) weren't Mosquitos more or less completely covered with fabric over the ply skin before painting? - So in effect wouldn't an unpainted airframe would simply be an off white, linen colour?

I can very strongly recommend the DH museum by the way. Lots of DH aircraft you can explore as well as several Mosquitos in restoration etc. They also had a section of the ply fuselage that you can pick up and look at - it is amazingly light.

Edited by Lotus 50 on Sunday 7th June 08:58

dr_gn

Original Poster:

16,140 posts

183 months

Sunday 7th June 2015
quotequote all
Lotus 50 said:
This is going to look amazing when finished, but, at risk of being pedantic (well, OK not "at risk" just being pedantic!) weren't Mosquitos more or less completely covered with fabric over the ply skin before painting? - So in effect wouldn't an unpainted airframe would simply be an off white, linen colour?
Come on..keep up! wink

dr_gn said:
I realise that this would never be possible (or extremely unlikely) in real life due to the way the aircraft was assembled and finished, but the idea is to give an impression of the different materials used in construction.
As far as I can tell, the bare surface wood (which whould be peppered with thousands of white dots where the screw heads were filled flush) would be covered with cloth/dope, then given a primer layer, then an aluminised paint for uv protection, then the final paint coats.


Lotus 50

1,009 posts

164 months

Sunday 7th June 2015
quotequote all
Ah, OK, apols read your post too quickly! I think you're right re the finishing. Aside from the light weight the other thing that amazed me about the construction of the skin was the relative thickness of the different woods - a very thin inner and outer skin (can't remember which wood was used for this) with a relatively thick balsa core so the overall skin is quite thick.

Anyway, looking forward to seeing the final result!

Edited by Lotus 50 on Sunday 7th June 09:36

dr_gn

Original Poster:

16,140 posts

183 months

Sunday 7th June 2015
quotequote all
Lotus 50 said:
Ah, OK, apols read your post too quickly! I think you're right re the finishing. Aside from the light weight the other thing that amazed me about the construction of the skin was the relative thickness of the different woods - a very thin inner and outer skin (can't remember which wood was used for this) with a relatively thick balsa core so the overall skin is quite thick.

Anyway, looking forward to seeing the final result!

Edited by Lotus 50 on Sunday 7th June 09:36
I think it was Douglas Fir veneer sandwiching Balsa wood. Exactly the same concept as carbon/foam sandwich in more modern applications: The skins take most of the loads, the low density core keeps them separated giving more stiffness:weight.

Incidentally I still can't find any comprehensive diagrams showing the complete break-down and orientatons of the outer skins, so I'm having to make some assumptions.

Lotus 50

1,009 posts

164 months

Sunday 7th June 2015
quotequote all
FWIW in "Mosquito: the original multi-role combat aircraft" there's some info on construction that may help:

"The prototype's wing, with a span of 55 feet 10 inches (slightly smaller than on later production machines), was manufactured in one piece from tip to tip It was built up around two wooden box spars with laminated spruce flanges and plywood webs. To develop compression in the birch, plywood double skins were used separated by spruce stringers. A false leading edge, built up of nose-rib formers and a D-skin was attached to the front spar. The whole structure was screwed glued and pinned before being finally covered with fabric over the plywood. They hydraulically operated slotted flaps, fitted between the fuselage, engine nacelles, and ailerons were also of wooden construction. Ailerons were metal framed and skinned, incorporating controllable trim tabs..."

"The oval-section fuselage, was also constructed from wood which offered the advantage of jig-building in two halves complete with seven bulkheads. The fuselage was built up from laminations of cedar ply, separated by a layer of balsa wood. At the point where the bulkheads were attached the balsa core was replaced with a spruce ring. For local strengthening, where attachments were made to the skin, a bakelite plug was inserted into the balsa with a plywood flange glued to the inner surface to spread the load. The join line was along the vertical centre plane, the two halves being scarfed together with fee notches reinforced by ply inserts above and below and an additional overlapping ply strip on the inside of the joint... ...The underside of the fuselage was later cut out to accommodate the wing, which was attached via four massive pick-up points with additional bolts passing through the bottom flanges of the inner ribs. The lower portion of the fuselage was then replaced after assembly, the whole structure covered with Madapolam, doped, then painted."

"The tail surfaces were conventional in desing, but all fixed surfaces were wooden structures consisting of two box spars and stressed plywood skins, while the rudder and elevators were aluminium with fabric covering."

The book isn't that clear on what changed in the production versions but things that it does mention are - the lengthening of the engine nacelles, strakes along the fuselage to strengthen it, metal skinned ailerons replacing fabric. In a later section on construction the author says that the inner and outer fuselage skins were birch ply separated by balsa with laminated spruce strengthening around the bulkheads etc... The description of construction is very detailed so it might be worth getting (you can get it on Kindle etc) the spec for doping (for the version produced in Canada) the fabric cover was to use a red-brown dope then grey filler followed by wet sanding, finally using two coats of aluminium cellulose. In finishing this was then covered by two coats of sea grey then the fuselage was masked at "83 degrees tangent" and the top surfaces sprayed with 2 coats of ocean-grey and two coats of olive-grey then camouflaged.

There's lots of photos of the construction process which may help but sadly no plan showing surfaces...

Lotus 50

1,009 posts

164 months

Sunday 7th June 2015
quotequote all
FWIW in "Mosquito: the original multi-role combat aircraft" there's some info on construction that may help:

"The prototype's wing, with a span of 55 feet 10 inches (slightly smaller than on later production machines), was manufactured in one piece from tip to tip It was built up around two wooden box spars with laminated spruce flanges and plywood webs. To develop compression in the birch, plywood double skins were used separated by spruce stringers. A false leading edge, built up of nose-rib formers and a D-skin was attached to the front spar. The whole structure was screwed glued and pinned before being finally covered with fabric over the plywood. They hydraulically operated slotted flaps, fitted between the fuselage, engine nacelles, and ailerons were also of wooden construction. Ailerons were metal framed and skinned, incorporating controllable trim tabs..."

"The oval-section fuselage, was also constructed from wood which offered the advantage of jig-building in two halves complete with seven bulkheads. The fuselage was built up from laminations of cedar ply, separated by a layer of balsa wood. At the point where the bulkheads were attached the balsa core was replaced with a spruce ring. For local strengthening, where attachments were made to the skin, a bakelite plug was inserted into the balsa with a plywood flange glued to the inner surface to spread the load. The join line was along the vertical centre plane, the two halves being scarfed together with fee notches reinforced by ply inserts above and below and an additional overlapping ply strip on the inside of the joint... ...The underside of the fuselage was later cut out to accommodate the wing, which was attached via four massive pick-up points with additional bolts passing through the bottom flanges of the inner ribs. The lower portion of the fuselage was then replaced after assembly, the whole structure covered with Madapolam, doped, then painted."

"The tail surfaces were conventional in desing, but all fixed surfaces were wooden structures consisting of two box spars and stressed plywood skins, while the rudder and elevators were aluminium with fabric covering."

The book isn't that clear on what changed in the production versions but things that it does mention are - the lengthening of the engine nacelles, strakes along the fuselage to strengthen it, metal skinned ailerons replacing fabric. In a later section on construction the author says that the inner and outer fuselage skins were birch ply separated by balsa with laminated spruce strengthening around the bulkheads etc... The description of construction is very detailed so it might be worth getting (you can get it on Kindle etc) the spec for doping (for the version produced in Canada) the fabric cover was to use a red-brown dope then grey filler followed by wet sanding, finally using two coats of aluminium cellulose. In finishing this was then covered by two coats of sea grey then the fuselage was masked at "83 degrees tangent" and the top surfaces sprayed with 2 coats of ocean-grey and two coats of olive-grey then camouflaged.

There's lots of photos of the construction process which may help but sadly no plan showing surfaces...

dr_gn

Original Poster:

16,140 posts

183 months

Sunday 7th June 2015
quotequote all
Thanks for that ^^ I'll have a read through it later. I'm intrigued by the angle/masking comment. I wonder if it's something to do with getting the right degree of feathering on the demarcations? Mosquitos do seem to have less well defined edges than Spitfires or Hurricanes of the same era.


dr_gn

Original Poster:

16,140 posts

183 months

Sunday 7th June 2015
quotequote all
So this illustrates the problems I have with oil paint woodgrain (and why I was keen to try decals):



The first panels I did (the lighter ones) were masked off and more oils applied in another direction.

1) It's very difficult to judge the amount of oil paint to remove during the graining process. The second panels are much darker than the first, even though I assumed they'd look similar. As it stands there is too much contrast for my liking.

2) Even though I used Liquin drying medium again, the paint hasn't dried. The first panels went matt within a few minutes, whereas these look like they could take weeks to set, judging by how similar they look to my SE.5a parts did (in terms of sheen). Obviously there can be no masking before the oil is fully cured.

So there you go. I wondered whether to try using enamels instead of oils for the grain, after all its a dissimilar paint to the acrylic basecoat, and has the same thinners, but they dry predictably...so why not? In fact why use oils over enamels in the first place - it's not like oils are widely used in model aircraft modelling to start with?

A long way to go with this one I think.



AER

1,142 posts

269 months

Monday 8th June 2015
quotequote all
dr_gn said:
Incidentally I still can't find any comprehensive diagrams showing the complete break-down and orientatons of the outer skins, so I'm having to make some assumptions.
This might help some - https://www.facebook.com/pages/Mosquito-Aircraft-R...

dr_gn

Original Poster:

16,140 posts

183 months

Monday 8th June 2015
quotequote all
AER said:
dr_gn said:
Incidentally I still can't find any comprehensive diagrams showing the complete break-down and orientatons of the outer skins, so I'm having to make some assumptions.
This might help some - https://www.facebook.com/pages/Mosquito-Aircraft-R...
Good references there, thanks very much thumbup

dave-the-diver

243 posts

185 months

Monday 8th June 2015
quotequote all
"the lengthening of the engine nacelle"

The prototype is currently in pieces at the de Havilland Aircraft Museum (formerly the Mosquito Museum), and the outline of the original, shorter, nacelles is clearly visible. I think there might also be brackets left over from a dorsal turret mock-up still visible?

Just to add to the recommendations above, the museum is a really good place to visit, good exhibits, nice people and a very worthwhile cause.

http://www.dehavillandmuseum.co.uk/

David

dr_gn

Original Poster:

16,140 posts

183 months

Friday 12th June 2015
quotequote all
I'm still figuring out the subtleties of woodgrain (Alex from UvdR has been very helpful with this), so in the meantime I made a start on cleaning up cockpit parts and assembling the engine nacelles etc. There are a few ejector pin marks still to fill in the wheel wells, and I'm not sure if the ones in the cockpit are covered by random bits of office furniture or not, but it looks OK so far:




EskimoArapaho

5,135 posts

134 months

Saturday 13th June 2015
quotequote all
4321go said:
It might just be the photo, but those props don't look the same. Each sprue seems to have one broad-chord prop and one with a narrower chord and more pointed tips.
I agree, and my guess: the two different types of propellor are supplied to allow the builder to do either an accurate static model or an accurate in-flight model. Because de Havilland put that clever variable pitch thingummy* in the Mosquito.

Dr_gn - I've got half a dozen random photos from the museum - I could email if you like?

* Sort of like an early version of VTEC, right? wink


dr_gn

Original Poster:

16,140 posts

183 months

Saturday 13th June 2015
quotequote all
EskimoArapaho said:
4321go said:
It might just be the photo, but those props don't look the same. Each sprue seems to have one broad-chord prop and one with a narrower chord and more pointed tips.
I agree, and my guess: the two different types of propellor are supplied to allow the builder to do either an accurate static model or an accurate in-flight model. Because de Havilland put that clever variable pitch thingummy* in the Mosquito.

Dr_gn - I've got half a dozen random photos from the museum - I could email if you like?

* Sort of like an early version of VTEC, right? wink
Sure, I'd love to see the pics - please pm me and I'll give you my email.

Yes, 4321 was right, they are different: Early and late versions. The physical shape of the blade wouldn't change with pitch, each blade just rotates about it's axis.

EskimoArapaho

5,135 posts

134 months

Monday 15th June 2015
quotequote all
dr_gn said:
Sure, I'd love to see the pics - please pm me and I'll give you my email.

Yes, 4321 was right, they are different: Early and late versions. The physical shape of the blade wouldn't change with pitch, each blade just rotates about it's axis.
PM sent. I thought the photo might be showing the same blade shape just presented at a different angle to the camera. But I sit corrected. smile

jamieduff1981

8,022 posts

139 months

Monday 15th June 2015
quotequote all
dr_gn said:
Lotus 50 said:
This is going to look amazing when finished, but, at risk of being pedantic (well, OK not "at risk" just being pedantic!) weren't Mosquitos more or less completely covered with fabric over the ply skin before painting? - So in effect wouldn't an unpainted airframe would simply be an off white, linen colour?
Come on..keep up! wink

dr_gn said:
I realise that this would never be possible (or extremely unlikely) in real life due to the way the aircraft was assembled and finished, but the idea is to give an impression of the different materials used in construction.
As far as I can tell, the bare surface wood (which whould be peppered with thousands of white dots where the screw heads were filled flush) would be covered with cloth/dope, then given a primer layer, then an aluminised paint for uv protection, then the final paint coats.
That's correct. The first coat on top of the Irish linen was dark red. The silver went on top of that, then whatever paint scheme on next. All plywood skins glued and screwed to frames/ribs/spars beneath.

Wing, flaps, fuselage, tailplane and fin were wood. Nacelles, ailerons and elevators metal skinned, rudder fabric skinned. smile

dr_gn

Original Poster:

16,140 posts

183 months

Monday 15th June 2015
quotequote all
EskimoArapaho said:
dr_gn said:
Sure, I'd love to see the pics - please pm me and I'll give you my email.

Yes, 4321 was right, they are different: Early and late versions. The physical shape of the blade wouldn't change with pitch, each blade just rotates about it's axis.
PM sent. I thought the photo might be showing the same blade shape just presented at a different angle to the camera. But I sit corrected. smile
I get what you mean now. I've not seen a kit with those options although a few kits have separate blades that you could pose in different positions.

sad61t

1,100 posts

209 months

Friday 19th June 2015
quotequote all
Hi dr_gn,
There's a brief shot of a part built Mosquito at a Canadian museum here:
https://youtu.be/ZE8d3ChFuAM?t=17m10s

At about 17:20 it is shown in what looks like bare wood finish, they are using all the actual materials and an authentic manufacturing process. More info here: http://www.ch2a.ca/#!mosquito/c1tsl