Landships II

Front and rear elevations at 1:36. Much work still to do here.

Looking good! Pencil and paper still can't be beat for all the early work.

H x

Fair do, whatever you're comfortable with. I like using vector graphics packages for drawing technical things, such as vehicles, machines, ships etc., because the precision achievable is amazing, and repetetive elements (e.g. track links) are easy to deal with. On the other hand, for organic subjects pencil/pen and paper are hard to beat.

-- Edited by Roger Todd on Thursday 17th of January 2013 01:14:11 AM

Looking good! Shame you don't have a vector graphics package, as then you can amend things very easily. Even a reasonably simple one like an early Corel Draw would do (I made all my Flying Elephant and Macfie drawings in Corel Draw 9, which is ancient).

I certainly didn't mean to kick-off the whole "paper vs. computer" debate for drafting.

Though they may have a steep learning curve (and wear out your eyes from staring at the monitor!), there are plenty of free and open-source 3D modeling programs available (FreeCAD, Google Sketchup) that allow you to export to 2D drawings, there are also some free dedicated 2D programs offered by big companies like Siemens (http://www.plm.automation.siemens.com/en_us/products/velocity/solidedge/free2d/) and Dessault Systemes, who makes Solidworks (http://www.3ds.com/products/draftsight/free-cad-software/).

For purely vector-based drawing, it looks like there's a lot of free options available (http://en.wikipedia.org/wiki/Comparison_of_vector_graphics_editors)

Of course, maybe we should ask the resident CAD expert what she is using (TurboCad?)

Fear not, Mr Timbers, I for one take no offence over the matter; CAD is undoubtedly best for accuracy, and the programs you have listed will be worth thinking about - so thanks for posting.

Roger is absolutely right about repetitive elements like track links, and I would also add that trying to draw tracks with a 5.3mm pitch by hand is far from precise.

I intend to alter the turret and other details, plus I need to figure out other details and proportions; I think the rear-side faces of the turret should be straight, and the height will have to be adjusted to get the proportions right - the central ridge of the roof should slope more steeply than the top edge of the front-side face (above the side MG mounts), but trying to get this to work without upsetting other measurements is a puzzle.

1:36 was suggested by R Simmie for easy reduction to 1:72, which is what most modellers work in; it also enlarges easily to 1:18, which would suit me for a radio-controlled model at some point in the dim and distant future.
1:35 would obviously be a good choice, but 1:32 is one of those scales that never quite caught on.

Overall length is 30 feet for the full-size vehicle, precisely 127mm at 1:72. Height looks fairly reliable at 9ft 2.5in, scale size 38.98mm; width however, is a more shaky matter. MM magazine states 7ft 5in, as does the Tanks website at Florida State Uni, but I think James H quoted 7ft 3in from a D Fletcher book in a previous thread. My own rough calculations from photos (which can only yield rough figures, given the distortions of perspective) suggest 7ft 3in is the more likely figure, however not as an overall figure, but as a value for most of the length: that is, the width across the tracks,not the width at the rear where the drive chain casings protrude beyond the tracks.

For this reason I'm having to use a bit of guesswork and trying to get the proportions right. 

One thing to bear in mind with the height is that the driver's cupola may be a pop-up design. My drawings so far suggest that the cupola will only fit inside a 9ft 2.5in height if what appears to be a vision gap all the way round is equivalent to a rhomboid-cab vision flap in the open position - so that the closed-down position lowers the whole cupola like a hat, reducing the overall height.

I have started a new set of drawings, again at 1:36 scale, with a slightly lower sprocket position and slight adjustments to other measurements. The drawings will not be finished for a while, but to test the accuracy I have made a simplified paper model at 1:72 scale.

For the most part I am satisfied with the result: the turret needs some more tweaks (although it is improved over my earlier drawing), but I think the track frames look right, so I can concentrate on other areas.

I hope to post some pics of the paper model tomorrow.

Here's the first pic - unfortunately I seem to have trouble uploading more than one file per post, so there will have to be a long string of posts.

Apparently you have to write something as well as post pics

Five

Trying again.

Rear upper view: the model is as I said before, simplified, the intention being to see if the profile of the track frames and shape of the turret look right. The back of the hull (and the floor of the hull) is thus basic, not accurate - the mud-shutes are drawn-on too, for ease.

Right side view - showing the fore-aft rake, which I currently have at roughly 3.8 degrees, the correct angle to meet the original design requirement to cross a four-foot-high obstacle at one end and a six-footer at the other.

Plan view

Nearly finished - some of these pics are very similar to each other, but I was trying to show the effect of perspective on the slope of the tracks.

Last one, I think - the order is higgledy-piggledy, because of the problems uploading earlier. I'm not quite sure if these are the best angles, but they should show the shape of the model well enough.

The turret needs some work, to adjust the contour of the roof and deepen the sides where they sponson-out over the tracks; this is supposed to be the Fowler turret, with the curved roof and deepening sides, but it looks more like a blend of the Fowler and the Wolseley. I may try drawing both turrets and make them up at 1:36, to make the shape clearer than it is at 1:72. The Wolseley turret has a chine down the middle of the roof and the forward face of the turret 'wing' (or sponson) does not increase in depth like the Fowler turret does; all the increase in height happens behind the 'wing'.

It compares pretty well; I had wondered if the two-stage lift of the track (at the back) would look right, but it matches very well. Working out the heights for idler and sprocket was no easy feat - and I may well be several cm off (I chose a lower value from the likely range, to provide enough height for turret and cupola), but the overall effect looks fine.

The turret is obviously a difficult shape to get right; I think it needs to be a little taller in places, with the points of the 'wings'/sponsons moved forward a bit. It won't be easy, but the result so far is definitely an improvement over the partial plans I posted three weeks back.

Next task is to adjust the turret, then try a larger-scale model (just the turret) to check the shape. This is necessary, because mapping out the shape of curved/angled panels (as flat panels) is tricky, and I have to figure out a better way of doing so for the roof.

Looking very good!