Tesla disc turbine: Allis-Chalmers record and later measurements, 2026-10-08

Google (Chrome) and IIT Kharagpur faculty pages (curl). Investigator (STEP I).

Queries

Dahlstrand Tesla turbine Allis-Chalmers report 1911 OR 1912 "Hans Dahlstrand"
Tesla disc turbine experimental efficiency measured "test rig" OR "multiple-disk turbines" Rice 1965 OR Guha 2009
archive.org title:(tesla) AND (dahlstrand OR "allis-chalmers") (no hits)

Negative for a primary copy: every hit (tuks.nl / Frank Germano pages, welchco.com, essra.org.cn, dokumen.pub copies of Seifer and O'Neill, Scribd) quotes the same passage beginning "Hans Dahlstrand, Consulting Engineer of the Steam Turbine Department, reports, in part: We also built a 500 kw steam turbine to operate at 3,600 revolutions", which is O'Neill's Prodigal Genius text already in the folder. No original Allis-Chalmers document was found. Records to try: Allis-Chalmers Manufacturing Co. records at the Milwaukee County Historical Society or the Wisconsin Historical Society (not searched).

Saved: research/files/hoya-guha-2009-tesla-turbine-test-rig.pdf, from https://facweb.iitkgp.ac.in/~aguha/research/Hoya_Guha_IMechE_PartA_2009_Tesla_Turbine.pdf (G. P. Hoya and A. Guha, "The design of a test rig and study of the performance and efficiency of a Tesla disc turbine", Proc. IMechE Part A: J. Power and Energy 223 (2009) 451-465; author's posted copy).
Their review of earlier work [web: p.452]: Armstrong (1952) ten-disc turbine, 1.11 hp, 14 per cent; Rice (1965, J. Eng. Power 87, 29-36) and Beans also built machines; later turbines generally below 2 hp, efficiency "between 20 and 35 per cent".
Their own 92 mm turbine [web: results section]: maximum 140 W (0.2 hp) at 25,000 r/min, efficiency about 25 per cent at that point, inlet total pressure 3.8 bar; they found nozzle losses large and say improving the nozzle is needed for overall efficiency.
Same author's site also lists: Guha and Smiley 2010 (IMechE A, Tesla turbine), Guha and Sengupta 2012-2018 papers on the rotating flow and pathlines (not downloaded).
How it bears: these are measured figures by others for small turbines (well below Tesla's 200 hp), in the same range as the 27-52% recomputed in claims.md for Tesla's own figures, and below Tesla's stated 80-90%. Guha's group attributes much of the gap to the nozzle rather than to the disc principle, which supports the inventor's point that the rotor itself can be efficient; reviewers should weigh that distinction.