Oh, yes, forgot about the "Hush-Hush":

http://www.lner.info/locos/W/w1.shtml

That web page has more than you'd ever want to know about the LNER's water-tubed 4-6-4, but note that it makes NO mention of a fatality, because that never happened.

Did I confuse that incident with another locomotive? Not sure....

The British experimental high-pressure water tube locomotive that suffered a severe accident and a fatality was LMS No. 6399, a modified Scott class named Fury.

http://en.wikipedia.org/wiki/LMS_6399_Fury

http://www.aqpl43.dsl.pipex.com/MUSEUM/ ... y/fury.htm

The 6399 would late be rebuilt to a Class 2 or 2A, and renumbered and renamed to No. 6170, British Legion. In this form the locomotive ran until retirement and scrapping in 1962.

http://en.wikipedia.org/wiki/LMS_Royal_ ... ish_Legion

An important point to consider is that this locomotive, along the the Canadian Pacific experimental 2-10-4 mentioned earlier and an experimental New York Central 4-8-4 that long predated the Niagaras all used an unusual triple-pressure boiler, using a closed steam circuit with distilled water at very high pressures (in the Fury, over 1,300 psi!) to transfer heat from the firebox to an intermediate pressure vessel (which itself ran at 900 psi in the Fury). The closed circuit heat transfer system was used to get away from the problems of scaling, hence its operation in a closed circuit with distilled water.

http://www.aqpl43.dsl.pipex.com/MUSEUM/ ... hptech.htm

None of these machines worked well due to the their complexity. Of particular interest is that the NYC supposedly used that 4-8-4 in hump service for years! Likely that was to keep the engine close to home, and to get some use out of the money tied up in it.

http://www.aqpl43.dsl.pipex.com/MUSEUM/ ... /USAhp.htm

http://www.aqpl43.dsl.pipex.com/MUSEUM/ ... nadaHP.htm

http://www.aqpl43.dsl.pipex.com/MUSEUM/ ... rmhigh.htm

http://www.aqpl43.dsl.pipex.com/MUSEUM/ ... P.htm#241b

Source page for all the above:

http://www.aqpl43.dsl.pipex.com/MUSEUM/ ... coloco.htm

Also from there, more on LNER 10000, the "Hush-Hush:"

http://www.aqpl43.dsl.pipex.com/MUSEUM/ ... /10000.htm

Here is some video of the Hush Hush.
http://www.britishpathe.com/video/l-n-e ... ush-engine

60000 4-10-2 at franklin institute in philadelphia is watertube.

Jawn Henry used a Water tube.

Many of the boiler examples given here, such as the B&O locomotives, are not true watertube boilers. They are firetube boilers with watertube fireboxes. This gets rid of the staybolted firebox with its large, flat sheets in the interest of allowing increased boiler pressure and eliminating staybolt maintenance. This seemed to retain most of the advantages of firetube boilers, including a large steam storage space and the fact that a firetube boiler is structurally self-supporting.

Some of the examples like (IIRC) the NYC 4-8-4 and the British Fury were true watertube boilers. N&W no. 2300 Jawn Henry had a true watertube boiler. Adapating a 100% watertube boiler to a locomotive brings a whole other round of complexity due to the difficulty of physically arranging and structurally supporting the boiler on a locomotive frame.

It seems like watertube boilers were thought to be the "Holy Grail" of making a truly efficient steam locomotive up through the 1950's. OTOH, Ing. L. D. Porta apparently never saw the need for watertube boilers for locomotive applications, reasoning that there were many other design improvements that could be implemented on steam locomotives to achieve great efficiency improvements without requiring them.

the diesel push just blew steam development, there ya goes...

I wouldn't call a Sentinel boiler a flash type boiler - there's a pretty good description here:
http://en.wikipedia.org/wiki/Sentinel_boiler

That class of boiler will take approx 1 hour to steam from cold, and the tubes are (or should be!) always completely covered with water. The superheater will act as something of a flash type boiler if someone were to... ahem... overfill the boiler at all. And should someone do that, you certainly feel the loss of superheat for a while! Or so I'm told.