De Havilland Mosquito

[Hobbes]

Hi Joe,

According to the Sharp / Bowyers book (supposedly the bible on Mosquitos), it says it would have been an exact scaled up version of the Mossie. The only dimensional information I have been able to find for it is in the same book (and I've looked everywhere), which says it would have had fifteen foot diameter contra-props.  So I took a photo of the drawing in the book and scaled it until I got 15 feet across the prop tips with the resulting comparison I did with a regular Mossie. ...

Looking at the image, I get the feeling the props might be three-bladed. The prop cone does not show a blade in the horizontal position (which you'd expect if there were a 4-bladed prop with 2 blades vertical and 2 horizontal). In that case, your measurement is off, because the drawing does not show the full length of the blade but shows a blade at a 60 degree angle (i.e. shorter). Does the Sharp/Bowyers book say what props were to be used?

[kitnut617]

Looking at the image, I get the feeling the props might be three-bladed. The prop cone does not show a blade in the horizontal position (which you'd expect if there were a 4-bladed prop with 2 blades vertical and 2 horizontal). In that case, your measurement is off, because the drawing does not show the full length of the blade but shows a blade at a 60 degree angle (i.e. shorter). Does the Sharp/Bowyers book say what props were to be used?

Good point and one I took into consideration, the image actually doesn't show either way.  If it was a three blader and the two are shown at 60 degrees, you would either see the horizontal prop on the near side if the two props shown were on the far side, or you would see the root of the blades inside of the spinners profile if the blades were drawn on the near side.  Same with if it was a four blader, you would definitely see the horizontal prop which doesn't show at all, in either scenario . All I can say is that the two that are shown measure the same length, but a couple of things did tally.  First was when I placed the Tempest Mk.I front fuselage over the drawing once I had scaled the props as shown to 15 feet, it was almost an exact match, the second thing is the opening for the cockpit in the drawing almost matches the the opening on the 1/72 Mosquito I overlaid which you can see in the photo I posted.  I've used one of the Tempest Mk.I conversions already but I have another --- somewhere, I'll try to find it and the drawing I printed off some time ago and take a photo of it overlaid.  

But I do agree everything is very speculative and as there isn't any concrete evidence to scale it with, I'm going to go with what I've got.  The only mention of the prop size is actually in the Putman book.

As an aside, I do drafting and design for a living and when I do a concept I just generalize what the shape will look like, exact details are worked out later. So if I was doing this very basic drawing, I would have drawn it like it's shown, which is why I've gone the route I've taken.

[kitnut617]

I found an example of how a three bladed prop would look like when detailed better and shows what I'm trying to describe in the last post. I did this for a design I did some years ago which you can see in the 'Gallery' section of the forum.

[kitnut617]

OK, while looking for something else in the stash, I found my 1/72 Tempest Mk.I conversion, here's what I mean when I scale Jon's pic down to have 15 feet across the prop tips and then overlay the Tempest conversion, practically bang on IMHO.

EDIT: added Putman quotation

[kitnut617]

I found I had another photo to add to my case that this might be the right size, I did this one sometime ago.  The cockpit canopy ends up being the same size as the regular Mossie and when I lined up a Mossie kit with the cockpit on the drawing, that almost matched up.  The only thing I need to find out is where the drawing came from, I know I've seen it in a book somewhere.  The spinner BTW, almost matches a Sea Fury spinner.

EDIT:  Just did some more accurate measurements on the scaled down drawing.  I measured the length of the fuselage from the nose tip to tail tip (not including the spinner) and I got 8 11/16" (221mm), then taking the real dimension of a Mk.IV as an example ( the nose protrudes in front of the spinner here) which is 40'-6", I found I actually need a 1/56 kit of a Mosquito to make a 1/72 Sabre Mosquito.

[jcf]

Hi Robert,
I pulled the side view out of Air-Britian Aeromilitaria Vol. 31, Issue 121, Spring 2005, its from an Out of The Archives
piece written by Tony Buttler. The text gives a wingspan of 65 feet and a length of 47 ft 6 in for the Sabre aircraft.

The Sabre powered 'Aircraft B' drawings are accompanied by drawings of a similarly sized twin Halford powered 'Aircraft A'.

Jon

[kitnut617]

Hi Robert,
I pulled the side view out of Air-Britian Aeromilitaria Vol. 31, Issue 121, Spring 2005, its from an Out of The Archives
piece written by Tony Buttler. The text gives a wingspan of 65 feet and a length of 47 ft 6 in for the Sabre aircraft.

Jon

Thanks Jon, I knew I had seen it somewhere.  I've got that issue but not here -- in the storage container.  The length is interesting as I've scaled the drawing to 52'-10 when I make the props 15 feet, I've got five feet to lose somewhere.  I think some of it might be in the tail area though, it's truncated a bit so doesn't exactly match the standard Mossie's tail end.  I'll play around with it a bit more.  I wonder where Tony got the dimensions from, I haven't been able to find anything in the books I have.

[kitnut617]

Here's something that has been puzzling me, a Mk.IV overall length is 40'-6" (reference out of Putman's book), a Mk.XVI is 44'-6" and the difference between the two are the engines. On the Mk.IV, the fuselage nose sticks out in front of the spinners but on a Mk.XVI the spinners stick out in front of the fuselage. But the extent that the Mk.XVI spinners stick out is only about 9" to 1 foot, so where is the other three feet?  Does this mean the fuselage on all the two-stage Merlins was longer than a standard one?  This would be something to take into account when trying to scale this Sabre Mossie.

[jcf]

Buttler's quoted length is fuselage length rather than overall length, so just for giggles
I rescanned the drawing and scaled it to approx. 1/72 using the 47' 6" measure, however
I measured from the nose to the rudder post rather than nose to tail.

I then scanned a two-stage Mossie NF 3-view from the Putnam British Fighters and scaled it to approx. 1/72
using the 44' 6" overall length measure and then overlayed the profile onto the Sabre Mossie. Now if my guess
on the Sabre Mossie fuselage length figure being measured from the rudder post was correct the difference would
be three scale feet or 1/2 inch. On the overlay its a shade under 9/16ths, which considering the line weights and
questionable source drawings is pretty close.

I also overlayed the NF profile and plan views on a Sea Mosquito 33 drawing also from the British Fighters volume,
make what you will of the result. 

Jon

[TsrJoe]

is there a concensus as to the size of the design? id measured the design as an overall length when making an example for photography (scale didnt matter for the useage being merly a 3d represeantation)

if you have a side and plan view of the 'sabre mossie' to hand, ill happily make it as a vacform for the group on here (are the wings a direct scale up too?)


cheers, Joe

[kitnut617]

I've done some scaling up and down too, when I scaled to Jon's posted dimensions, 47'-6" total length, a few things changed.  One, the nacelles became not much bigger than the Merlin nacelles on a standard Mosquito, and two, the cockpit canopy diminished in size too, being much smaller than a standard Mosquito cockpit canopy.  On the other hand, going by Hobbes suggestion that the view was actually showing the two prop blades at 60 degrees, it matched quite well, the vertical dimension for the blade tips being 12'-11 7/8" when at 60 degrees and the drawing measured 13'-2" when I put the rule to it.

But when I used the scaled down drawing with the props measuring 15 feet tip to tip, the measurement of 47'-6" from the rudder post to the nose is awfully close but I had to go to the tip of the spinner to get it.

Here's a couple of photos of the profile which was scaled to 47'-6" overall overlaying the profile scaled to have 15 feet over the prop tips.  Second photo just shows the difference between the nacelles better.  It shows that the smaller profile has nacelles no better than a Merlin, including the spinner, and also the difference between the canopy, I had already found that the larger profile almost matches the 1/72 kits for canopy and nacelle.  I know the standard Mosquito cockpit was really crowded so I can't imagine it would have been smaller.

[kitnut617]

One other thing, going back to where I needed to find where the difference of five feet was (back four or five posts) I think I've found it.  The tail end of the Sabre Mosquito is different to a standard Mossie (most of the fuselage is really), the Sabre Mossie doesn't have a nice tapering end to the fuselage.  If I was to make this have a nice tapering end I get this in the photo, about five feet    it is of course just guess work.

[sequoiaranger]

Regarding the EXACT dimensions of the up-sized Mossie:

I think it is always fun to re-create a "real" whif and bring it alive. To me, however, it seems that "we" are trying too hard to come up with the EXACT dimensions when, in most cases, a REAL aircraft evolves a bit from its drawings anyway. No sheet metal (plywood?) was cut to make this enlarged Mossie, as I recall, so "we" can easily excuse minor design changes in order to achieve a believable end product.

I just *WISH* I had my 1500-kit stash (sold off a couple years ago). I'm sure there is a Russian, Italian, or Japanese aircraft kit out there that would form a reasonable base fuselage for you to recreate the enlarged Mossie, and that's JUST the sort of thing I used to enjoy doing (sleuthing a whif from the shapes and sizes of my stash). But Alas!

You MIGHT try (as I did with my Grumman Gander pedastal float) merely adding some thick spacer(s) to a 1/72 fuselage to enlarge it diametrically, and some constant-diameter "rings" (maybe even several thick spacer "bulkheads") to lengthen it where the wings (Hampden?) meet it.

I think it is do-able, and I am excited to think that it might happen. Never Despair!

[kitnut617]

Regarding the EXACT dimensions of the up-sized Mossie:

I think it is always fun to re-create a "real" whif and bring it alive. To me, however, it seems that "we" are trying too hard to come up with the EXACT dimensions when, in most cases, a REAL aircraft evolves a bit from its drawings anyway. No sheet metal (plywood?) was cut to make this enlarged Mossie, as I recall, so "we" can easily excuse minor design changes in order to achieve a believable end product.

You MIGHT try (as I did with my Grumman Gander pedastal float) merely adding some thick spacer(s) to a 1/72 fuselage to enlarge it diametrically, and some constant-diameter "rings" (maybe even several thick spacer "bulkheads") to lengthen it where the wings (Hampden?) meet it.

I think it is do-able, and I am excited to think that it might happen. Never Despair!

You're right --- the object on my investigation was to see what was available so I wouldn't have to do too much scratch building, the Hampden wings are a good example, along with the Tempest Mk.I conversion (it's still available) and standard Mossie canopy.  The drawing I have will go a long way towards checking out which parts fit best.  I even think a B-17B rear fuselage might work too, your He.111 idea got me thinking along that route.

[jcf]

In the Air-Britain piece Buttler does state the following:
"However, it must be borne in mind that these drawings, for designs which do
not show official De Havilland designations, were most probably preliminary
sketches and not part of a full brochure. Consequently, perhaps one should
not attach too much significance to them."