Miss Prism

I was thinking of Burghclere: http://www.kestrelrailwaybooks.co.uk/burghclere_files/image003.jpg But, silly question, weren't there two sets of apparatii, one for up and one for down?

Usually in the vicinity of the signalbox.

I see in one of your brass attachment pieces the attachment hole is a slightly elongated hole, presumably for some adjustment? Where did you get 0.026" solid guitar string from? - the largest solid I've encountered is 0.024".

Is this a lined Mogul?

Mmmmm..... Not many of these Panniers have normal spoked wheels (as in your Slaters), most had H-spokes. I haven't got my pics handy, but no doubt others can advise.

http://www.scalefour.org/shows/S4um2012/dorchester.html

Would have been nice to have used the improved 02 chimney.

I had wondered to ask, unless I missed something around posts 7 or 8, about boiler bands. Or are you sticking them on later?

Ah yes, of course. And I had looked at post 11 only a couple of days ago! (doh!)

Lookin' good. ATC shoe on the pony?

The advantage of 4-point over 3-point relates to lateral stability - it allows a greater freedom of the centre of gravity placement compared to 3-point. This is the achilles heel of 3-point, where, depending on the where the single beam is in the loco and its relationship to the CofG, locos can become unstable in the roll plane. Viz the preproduction version of Chris Gibbon's 0-4-2T, which fell off on curves, as predicted, and he redesigned it. As Chaz notes, natural axle to bearing clearances and the relatively small vertical axle movements allows 4-point to work well, even if the bearings are secured solidly in their beam (as in this case). In 7mm, the approx 5x loco weight compared to 4mm does help a bit in flexing the beams if they are thin, but I don't regard such flexing as an essential. In the general case, I feel a 4-point strategy is definitely superior to a 3-point one. P.S. 40:1 feels a bit fast to me for a loco that probably never exceeded 20mph. A larger slower motor might be the solution?

4-point compensation, which is what is supplied in the kit, is a bit of a fudge, although a reasonably pragmatic one. The bearings do pass through the frames (but check for easy clearance between the bearing body and the slots in the chassis side frames) and are soldered to the beams #3. These beams cope well with track irregularities that are symmetrical (on both rails). But real track is not like that of course, so 4-point compensation is strained when the beams do not move in tandem, because the bearings become misaligned: In practice, there will probably be enough axle to bearing slop to cater for this misalignment. Reducing the length of the bearing will help somewhat in this respect if you are worried about trying to cope with really bad track. The downside of having the axle to bearing slop is that it might not be easy to ensure the bearing pitch (held in the beams #3) aligns well enough with the coupling rod pitch. There's no such thing as a free lunch. Suggest check the pitch correlation with some alignment jigs before proceeding much further, i.e. solder the bearings in #3 according to the rod pitch. Love those instructions. It's no wonder people turn to CSBs these days...

There are two parts #3, which provide 4-point compensation, not uncommon in many 7mm kits. Perhaps not quite so agile as 3-point, but definitely more stable.

I'm not familiar enough with Navy steam turbines to comment, but I guess there could be significant differences between their bearings and what is going on in the pistons of a conventional reciprocating steam engine. Besides which, money was no impediment to the Admiralty! I think considerable improvements in oils took place throughout the Edwardian era, particularly with WWI, so yes, higher temperatures could have been incorporated on the GWR a lot earlier, and no doubt Churchward was aware of the potential improvements, but as ever, fitting a new generation of superheaters would have been expensive, and the larger locos were doing everything expected of them at the time, which is why Collett merely rang a few size changes (or stagnated, according to one's point of view). Higher temp superheating was not a priority for the large engines - the priority was to get some superheat into the vast army of the saturated smaller engines.

Also, Edwardian oils were not good at surviving higher temperatures.

The 1366 class didn't have rivets on the tanks.

The likely culprit is a mismachined chassis block that doesn't align with the rods. Can be sorted.

It's a shame the sides of the kit's tanks aren't flush with the sides of the cab sheets.

4-digits seem to be the norm for post-1892 NG opens, so I'm wondering if the 5-digit series was introduced for the BG conversions. It's true that 5-digit numbers featured also for later NG opens - many opens were categorised generically and retrospectively when the diagram number system was introduced.

Crikey - given the prototype rod bosses were probably thicker than the ones you're using, I'm wondering whether those outside valances are too close.

I'm trying to remember where I've seen a prototype pic of an ampersand on a shutter.

Very nice indeed. The touch of dark colour on the rivets between arm and spectacle plate is excellent. What was the source of the shape of the & on the shutter?

8-spoke wheels came in a thin-spoke type (for 6T to 8T) and a slightly thicker spoke type (for 10T to 12T). I'm not sure whether there was a hard and fast rule for the crossover weight for 10-spoke wheels, but I think it was probably 12T rather than 10T. Most (all?) Toads were 10-spoke, for example. Machinery wagons/trucks, e.g. Morels, Loriots, tended to have 10-spoke or even I think in some cases 12-spoke, depending on weight. The spokes of such wheels were chunkier still, like a loco carrying or tender wheel.

Given the body tilt angle is to be derived solely from track radius, it would seem the only way this could be implemented could be from the rotation of the bogie(s) relative to the body. Here is the bogie yaw to track radius relationship for the power car. I've not included the asymptote on the right-hand side of the plot, and it will be interesting to read at what radius the model's tilting mechanism 'kicks in'.

Ah, ok, that fits most of the evidence better. 3205 had a parallel in 1938 though, so I'm guessing any works visit (as distinct from a full monty boiler swap) could be when a chimney was changed.