New tool Mossie from Revell

[Edgar]

Trying to inject a little sense of proportion, here. The fin was made of wood, covered in wood, covered in fabric, and built by (though mainly skilled) a workforce normally employed in making furniture. Also, when Tamiya were researching for their models of the Mosquito and Beaufighter, they were seen crawling (figuratively speaking) all over airframes, preserved in UK museums, and they were using a camera which took measurements at the same time as the photos. Any possibility that the one that they measured might have had a fin slightly taller than another? In today's precision environment it pays to remember that the Mosquito was built, largely, with hammers, saws, screwdrivers and spokeshaves.

Edgar

[jenshb]

Good point Edgar. All things we make needs certain tolerances, so things will always deviate from the nominal. However, you always strive to make things as close to design intent as possible, hence the use of templates and jigs to minimise variation (and therefore deviation from the nominal). It would be interesting to measure preserved Mosquitos that haven't been rebuilt or had a tailfin replacement to see what variation you would get. To me a variation of 4 and a half inches sounds too much even if they used simple hand tools to make the plane.

Jens

[Edgar]

:) Putting my smarta--- hat on, 1.5mm = 2.8" in 48th scale; still a touch excessive, I grant you.

Edgar

[KOG7777]

So we don't know for sure yet which version of the Mosquito Revell will be releasing first? We just know that they are releasing 'a Mosquito'?

[Notdoneyet]

So we don't know for sure yet which version of the Mosquito Revell will be releasing first? We just know that they are releasing 'a Mosquito'?

It's a B Mk IV see Revell sprue shots here

HTH,

Ian

[KOG7777]

It's a B Mk IV see Revell sprue shots here

HTH,

Ian

Oh, thank you for the clarification.

[RKic]

I wonder if they'll scale down to 1/72. It would be nice to see that price an quality in the small scales.

The 1/72 Tamiya kits weren't bad, but they're becoming hard to come by

[Jennings]

Trying to inject a little sense of proportion, here. The fin was made of wood, covered in wood, covered in fabric, and built by (though mainly skilled) a workforce normally employed in making furniture. Also, when Tamiya were researching for their models of the Mosquito and Beaufighter, they were seen crawling (figuratively speaking) all over airframes, preserved in UK museums, and they were using a camera which took measurements at the same time as the photos. Any possibility that the one that they measured might have had a fin slightly taller than another? In today's precision environment it pays to remember that the Mosquito was built, largely, with hammers, saws, screwdrivers and spokeshaves.

Edgar

In a word: no. Airplanes are not built to specs that loose. They wouldn't fly if they were. Tamiya did not have access to any Mossie factory loft drawings when they did the kit, and going from photos and 3D measurements is never as good as going from factory production drawings. I know this to be true, since a friend of mine is an archivist at the NASM in Washington. When Tamiya were there sometime after the Mossie came out (looking at other things), he told them that NASM had a full set of Canadian production plans for the F-8 Mosquito. He said the Tamiya designer who had done their kit lost all the color from his face when the translation was completed. He nearly had kittens, not having had any clue to look under "F-8 Mosquito" when he was searching files.

I absolutely guarantee that all Mosquitos had vertical fins the exact same size, probably to a tolerance of 1/8" or less. You just can't build production airplanes with 4 1/2" tolerances on things like that.

J

[Edgar]

Obviously you know more about the factories, here in High Wycombe, than the men who worked there, so there's nothing more to be said. One small point, though, according to de Havilland's records, there was no such Mark as an F.8 Mosquito; a B.VIII, and a PR.VIII can be found, but no F.8.

Edgar

Edited November 6, 2008 by Edgar

[jenshb]

The only thing reliable about factory drawings are their dimensions unless the drawings are generated from 3D models - highly unlikely in the 1940s:) The drawings should also include tolerances on the components.

One of my ex colleagues worked for BAe and the flap for the Nimrod MR.4 conversion, and from what he said, the wings had to be built to fit specific fuselages as the wing attachment points varied by about 4 inches. True? I don't know, but given that the tolerance stack for a fuselage is longer than for a single component, I wouldn't be surprised if it was...

Jens

[Jennings]

Obviously you know more about the factories, here in High Wycombe, than the men who worked there, so there's nothing more to be said. One small point, though, according to de Havilland's records, there was no such Mark as an F.8 Mosquito; a B.VIII, and a PR.VIII can be found, but no F.8.

Edgar

No Edgar, but I've been around airplanes and engineers a lot. You simply don't build airplanes with *interchangeable parts* with 4 1/2" 'slop' built into them. It's impossible. How could rudders be interchangeable (much less balanced) if there was 4 1/2" difference in their height? For a mass production airplane, that's simply not possible. I'm sorry if that flies in the face of what someone told you, but I invite you to ask any engineer, production line worker, or aircraft mechanic about it (outside of High Wycombe apparently) and see what they tell you.

And yes, there was a Mosquito F (dash) 8, not an F (dot) 8. The USAAF had a whole bunch of F-8 Mosquitos from Canadian production. They were photorecon airplanes.

J

[Edgar]

Why this continual reference to 4.5", when 1.5mm is equivalent to less than 3", and has no-one remembered that Monogram's kit has a too-high fin, as well? Any chance that both companies measured the same airframe? With the Americans using "F" for photographic (and they complain about our spelling!) the Mark would have been, originally, the P.R.VIII.

It's no good applying modern tolerance limits to wooden aircraft of 60 years ago; talk to Paul Monforton, who's found up to 2" variation in some Spitfires, and they were not wooden. One workman told me how he was confronted with a mismatch, on a Mosquito wing, of over 1/2", which he was normally supposed to fill with a hand-made shim of spruce. He was in a hurry, so he just poured glue into the gap, and let it set. When it was discovered he was taken to the foreman, who was in the process of tearing him off a strip, when someone came in, and said that they'd discovered that his "bodge" (as it's known in the furniture industry) was stronger than the usual method, so it was decided that the same idea could be used in future.

Edgar

[jenshb]

The reference of 4.5 inches is to the scale difference in height between the Tamiya Mosquito's tailfin and the actual (measured) height, I don't know where the 1.5 mm comes in as the difference scales out to 2.4 mms, not 1.5. Anyway, tolerances must be seen in relation to the part being measured and the method used to fabricate it. A 1 mm difference on a 10 mm diameter turned part is huge, but few would be able to cut a 1metre piece of wood within 1 mm with a hacksaw. If the Spitfire varied with 2" over it's entire length, then that particular airframe could have had a combination of parts that were on the upper end of the tolerance and the tolerances add up. I doubt that he would have found a cockpit door or cowling panel with a 2 inch gap for example.

Jens

[thom]

Don't want to come down too heavily on either side of what's shaping up to be a very interesting discussion, but from what I remember reading about Spitfires the ones built at Castle Bromwich had to be serviced with Castle Bromwich 'parts', not Supemarine's own bits, because the jigs used to build them were slightly different. There simply wasn't time during the war to set up standardised production across several production lines (especially with rapid evolution), so aircraft from each line had their own quirks.

I imagine the same is perfectly plausible for Mossies, assuming the production was carried out in more than one place. That having been said, the Mosquito evolved more slowly than the Spit, and was produced in far smaller numbers, so standardisation of plans and production might easily have been achieved.

Is there a fence-sitting emoticon?

[jenshb]

Interesting point thom. The Mossie was made in Canada as well, so there may well have been differences in fixtures between the Canadian and UK built aircraft. The only way to check is to measure Mossies that are original.

Jens

[airjiml2]

I really can't speak to the tail height issue, but to be clear with the designations, Edgar is correct there is no such mark as a F-8 Mosquito in RAF, RCAF, or DeHavilland terms. But Jennings is correct that the F-8 was a USAAC designation. (Makes sense that the Smithsonian would file the plans under the U.S. designation.) I'm pretty sure most of the F-8s were build as B.VIIs or B.XXs and then converted to F-8 status, btw.

For more on Canadian Mosquito production see this excellent photo gallery:

Downsview Mosquitos

and/or Joe Holliday's book "Mosquito!"

Jim

[mossieramm]

Don't want to come down too heavily on either side of what's shaping up to be a very interesting discussion, but from what I remember reading about Spitfires the ones built at Castle Bromwich had to be serviced with Castle Bromwich 'parts', not Supemarine's own bits, because the jigs used to build them were slightly different. There simply wasn't time during the war to set up standardised production across several production lines (especially with rapid evolution), so aircraft from each line had their own quirks.

A few years ago I spoke to a mechanic at Duxford, and I asked him if he ever noticed the numbers along the fuselage on the Bf-109 ?? Apparently it’s so that if a panel needs replacing all you need is a number. I was wondering if British aircraft were standardized like that. He said no, any panel or part that needed replacing got made specifically for that particular aircraft. So any in discrepancy in dimensions is to be expected.

David.

[Edgar]

Several years ago, I was talking to the Westland historian, when he visited our local model shop, and he said that, when Westland did Spitfire repairs, they were able to take the panels/covers off a Supermarine, or Westland-built, airframe, and throw them in a heap, knowing that they could fit them to any similar airframe, but Castle Bromwich-built Spitfires had to keep their panels with them, because they would never fit any other.

You really must get rid of these romantic notions that everything was exactly right, during the war. Remember that any damaged part, on a Mosquito, couldn't just be unbolted, and replaced, they were glued, and screwed, into place. For speed, the broken part was sawn off, then the new one fitted, re-covered, and painted. Our IPMS treasurer delights in telling us about a man, who came up to him, at a show some time ago, who said that he'd worked at a repair depot, on Lancasters. One regular repair was to replace a wingtip, and, to save time, they were sent a drawing, to make their own. When they came to use one, they found that the drawing dimensions had been made from the wrong rib, and each tip was 12" wider than it should have been. They couldn't afford to waste time, making new ones, so the tip was fitted, with a matching extra-wide tip on the other wing, to balance things. This meant, he said, that some Lancasters flew with 2' greater wingspan than the spec. Shrug your shoulders, if you like, and dismiss it as nonsense, but stories used to abound about similar make-do occurrences.

Edgar

[Anthony in NZ]

This is actually a great discussion guys.

It brings me to an interesting point. I have visited Glyn Powell and also the Avspecs team who are building/rebuilding a Canadian FB26 Mossie KA 114 for Jerry Yeagen many many times over the last few years.

Whilst Glynn was building up the fuselage he had to decide which co-ordinates he was going to use as the variation between the British, Canadian and Australian built ones was remarkable. He showed me by placing an Australian made nose cap up against a British built one and there was just over an inch difference in dia (Aussie one smaller) and the Canadian one was slightly bigger(only just). Glynn decided to go with the UK built specs. Although an inch dosent sound like much, when you see them side to side it was amazing. The AvSpecs guys tapped the nosecap of KA 114 to shrink it down (amazing craftsmen) and made it fit.

I am not taking sides here as I like both your arguements, just thought it was interesting. I have been involved with our local museum for over 20 years as a volounteer and we have the remains of 2 FB-VI's NZ 2328 (TE758) & HR 339 (an ex 487sqn combat vet EG-J and 'H'. Earlier this year I was away on business and came across a huge pile of brand new Mossie parts in someones garage(including brand new perspex glazing for the canopy with 1944 stamps on them). What a haul! It has gone a long way to helping our project thats for sure.

If you get a chance check out Avspecs website to follow the progress on Jerrys Mossie, the workmanship is stunning. She will be completely stock again with Cannons and machine guns etc. Stu is slowly updating the site at the moment and so some more updates should be up soonish. http://www.warbirdrestoration.co.nz/current.html

Also there are some shots of her taken more recently at this cool site (one of my favourites actually if you like NZ aviation) Drop by http://rnzaf.proboards43.com/index.cgi and look up the preserving NZ aviation and look under P-40C & Mosquito update.

Cheers

Anthony

[Steve N]

I was talking to the one of the guys restoring the Bolingbroke at the Canadian Warplane Heritage a few years back. They're trying to combine several different airframes to get one flyable aircraft. I was told that their problem wasn't so much dimensional differences, but the fact that the locations of screw/bolt/rivet hole varied so much between airframes. He said they were hand-drilled using measurements, rather than jig-drilled..so even under fairly strict tolerances, there were still enough variations to make it difficult to interchange large airframe components.

I'm not weighing in on the Mossie tail issue..I work in 1/72, and not knowing enough about the bird, the Tamiya kit looks fine to me (just wish is had more detail in the bombay.)

SN

[Jennings]

Edgar - I've not doubt whatsoever that cases of oddball size things being jammed onto airplanes happened. I stipulate to that unconditionally. But there's a big difference between that and 4 1/4" tolerances on the size of vertical fins. Until someone shows me photos of Mosquitos with different size vertical fins and rudders, I simply cannot accept that deHavilland were incapable of holding airplanes inside a tolerance of over 5%. Maybe 0.5% I'd buy, but not >5%. Bolt holes in different places? Yes. Stamped sheet metal fairings of slightly different dimensions? Maybe. But jig-built major structural members that have a direct effect on aerodynamic performance? No way. Just not buying it, even from a British manufacturer making airplanes out of wood.

You can continue to argue this until everybody is blue in the face, and we'll probably never agree. But can you imagine for just a moment that Tamiya came close on their model without the aid of actual factory loft drawings (a fact, and they got remarkably close), but that the real thing is actually slightly different from the kit? Would your world collapse if that were the case? If so, why?

J

Edited November 7, 2008 by Jennings

[Grant in West Oz]

I'm just annoyed they've opted to ignore the long overlooked 2 speed 2 stage engined versions.

Who needs another Spitfire Mk.Vb or Mustang IV, they've been done to death.

Give us a variant that has yet to be adequately moulded.

Please.

Or do a 1/48 scale Beaufort VIII.

As for accepting 2.8" or 71mm variation in fin height. Plastic aircraft don't fly, so a model doesn't matter. A full sized wooden one simply wouldn't fly well. Ever heard of a 'Dutch Roll'? A constant instability which was un-trimmable. Completely unacceptable no matter the urgency.

G

[kozlok]

My best guess is that it's measurement differences combined with differences in the actual parts. I've seen people use sub-micron accuate coordinate measurement machines to measure the exact same part twice, and get millimeter size variation in measurement (the operator didn't know it was the same part). Due to the way things stack up depending on the accuracy of a specific locating surface, it's easy to wander way off (you're not measuring perfect square surfaces, so where's 0?). I'm going to guess that you and the Tamiya guy used different reference datums, and the way things stack off of those datums probably results in both measurement error and part-to-part variation.

[Heraldcoupe]

Anyone know which airframe(s) Tamiya measured? Given that many restored Mosquitos have somewhat checquered histories, a non-flying restored aircraft could have a tail built to any standard imaginable. Tamiya's Beaufighter includes many features appropriate to a certain resotred example, but which were never seen on any aircraft in service.

While interpretation of airframe shapes is highly subjective, actual dimensional inaccuracies are pretty rare in Tamiya aircraft kits made in the past 10 years. The tail may or may not be right for an in-service Mosquito, but I feel it's likely that it matches a rebuilt Mosquito somewhere in the world.

Cheers,

Bill.

[jester292]

Or...

If you think the tail of the Tamiya/Revell kits are too tall, fix 'em. If not, leave 'em...

Interesting discussion however.

Aaron

As far as "Dutch Roll"... Thats a swept wing issue...

Edited November 11, 2008 by jester292