Getting More Steam

From Amazon.com:


 * Invaluable handbook on how to get your live steam engine to burn its coal more efficiently and thus run longer and more smoothly between stops. About half the book is a very helpful essay, "Redesigning the Model Steam Locomotive for More Steam Output," detailing the author's experiments with firebox size and coal type as well as his reading of old Pennsylvania Railroad reports which opened his eyes to how to properly run a steam locomotive. The second half of the pamphlet is a reprint of a 1936 article from the Association of American Railroads, "Master Mechanics Locomotive Front End Arrangement," which addresses the same issues. Both articles are illustrated throughout with clear diagrams and charts. 36 pages.


 * Paperback
 * Publisher: Lenahan's Custom Railway Supply (1980)
 * ASIN: B000SMT2QS

Reviews
Rwilliams wrote on Chaski.org:


 * The late Jim Lenahan of Colorado did some extensive testing with his locomotive in regards to front end design and published a small booklet "Getting More Steam", on his results of smoke box design changes and how they changed the performance of his engine. One of his designs featured a double petticoat which may have produced an effect similar to the gap at the top of the petticoat on Ventura County #2.

Rwilliams also wrote:


 * Back in 1980, James Lenahan of Colorado published the results of his research on a small locomotive in his quest to get more steam. He had a poor steaming locomotive which needed change in the front end in a big way. His 3/4 inch scale steamer was the subject of many tests and the basis for his book, Getting More Steam.


 * Unfortunately, he passed on due to the end result of an air plane crash and is no longer with us. Copies of his book still do exist and are enlightening in regards to the recent discussions.

JJG Koopmans wrote on Chaski.org:


 * I was recently able to buy a secondhand copy of Lenahan’s text. Lenahan’s book is an interesting read. It describes his attempts to improve the poor steaming of his 3.5 in. Pacific. The second part of the book is a copy of the 1937 design guides of the American Master Mechanics front-end.


 * Lenahan’s Pacific was built as designed by an unnamed supplier with an orifice of 9/32 inch diameter, the chimney was straight with a diameter of 1.4 inch and a length of 2 inches. In our earlier thread I discussed already why these values are bad, the chimney to orifice diameter ratio = 1.4/ (9/32) or almost 5, way too big. The chimney length to diameter ratio = 2/1.4 = 1.42 and this cannot work properly at all, as shown by Lenahan’s experience.


 * Interesting in Lenahan’s approach to improvement was that he had access to reports of the Pennsylvania Railroad Tests of 1906 to 1924 where he found parts of his steaming problems described for real size locomotives. Since the Penn. RailRoad had used pressure measurement devices at the chimney exit and found a velocity or pressure distribution with a peak in the center, they speculated that a more even distribution would improve drafting. They proved this with elliptical and rectangular nozzles while over the years wedges projecting in the exhaust stream proved as effective.


 * Lenahan concluded that he could apply a triple exhaust with good effect and tested this with a model front end. A box with a chimney on top and an exhaust stand on which different layouts could be tested with an air pressure of 30 psi. The box contained 3 different holes to admit outside air. The vacuum generated was read from a water filled U-tube. With different chimneys and varying distances between orifice and chimney he got vacua that varied from ½ in to 1-3/8 in.


 * He then concluded that his straight chimney should have an entrance flare, a 1:10 taper, be at least 4 diameters in height and have only 3 orifice diameters as chimney diameter. The final triple orifice had an equivalent diameter of .262 in. distance .786 in. from the chimney which has a smallest diameter of .786 in. The exit diameter was 1.125 in. and the chimney length was 4.78 in.


 * It is a pity that no more data on the locomotive appear in the booklet, the cylinder diameter for one would be interesting to see whether the ratio orifice to cylinder diameter is in the normal range. In my humble opinion, the triple orifice could use some redesign as the orifices appear too close together. Apart from that the ratios found and used are proper, the smaller orifice to chimney distance would not be of a problem since the chimney is so long.