Talk:Curtiss H-1640 Chieftain

Diameter

" By aligning the cylinders the diameter of the engine was less than more conventional radial engines"

Is that how circles work? That must be the same as how when you cut a 16 inch pizza into 12 slices and remove 6 alternating pieces, the remaining pieces form a circle of 14" diameter. It's simple math. I think. The only thing that makes any sense is that maybe they decided that two aligned 6 cylinder banks are smaller than two staggered 7 cylinder banks in a normal radial. Otherwise that is just a factually incorrect statement. A circle is a circle. It might concievably be less frontal area exposed but it's hard to imagine the actual drag created would be less, or they were thinking of a 12-sided polygon shaped cowl, which would very slightly reduce the overall area. 2600:1000:B158:70E1:0:5D:2EC3:D901 (talk) 19:12, 31 March 2025 (UTC)

I have clarified the wording, the source uses the wording 'materially reduces the diameter'. The frontal area is stated as half that of a single-row nine cylinder engine. Nimbus (Cumulus nimbus floats by) 06:50, 1 April 2025 (UTC)

Applications

According to the article's Applications section, this engine was used on 4 different aircraft. The Specifications section used the www.EngineHistory.org website as a source, so I visited and read about the engine. According to this specific page, the engine "...never saw production." This article does not mention that at all, and indeed misleadingly states, "The H-1640 was the first airworthy 'inline radial'...". The Curtiss XP-22 Hawk article says the engine was a "failure"... The Curtiss YP-20 article says the same, and that the Chieftain was never part of the YP-20. The Curtiss P-6 Hawk article mentions the P-11 (in the Variants section) as having 3 ordered with the Chieftain, but 2 of those were completed with a different engine. There's no mention if the remaining P-11 was actually delivered. The Thomas-Morse XP-13 Viper article states that the aircraft delivered with the engine, but due to cooling problems was immediately replaced with another engine. So, how is the Applications list on this article factual? Anyone have a different reliable source that shows it went into active production and also lists those aircraft as truly having that engine? — TadgStirkland⁴⁰¹(Tadg^Talk-Email) 23:51, 2 September 2025 (UTC)