User talk:Cavalryman

Hello, I saw you had some interest in the Lanchester 38 HP. On a whim, I purchased the Anthony Bird profile book on this and the 40 HP, and I realize that I am wildly confused about the size of the engine. Right now, the article lists the engine dimensions as 101x101mm, which is then converted to 4x4in. Bird states 4 in x 4 in. However, he lists the displacement as "4800cc" while our article states 4896 cc (converted to 299 cuin).

However! When calculated, the displacements come out as follows:

• 101mm x 101mm = 4855cc
• 4in x 4in = 4942cc
• 4896cc if square means 3.987in, or a 3.981in bore with a 4in stroke

The 40HP, meanwhile, is listed as 5in x 4in and 6178cc, which does add up. This indicates that the 4-inch stroke, at the very least, is correct. Any ideas to the actual displacement? I expect it to be 4942cc, but I need to see it in black and white first. Best,  Mr.choppers | ✎  03:34, 30 January 2026 (UTC)

Hello Mr.choppers, I did an awful lot of searching for the Bird book online but could not find it anywhere. My source for that is the Robson & Ware book Classic British Cars^[1], which includes a little infobox which has the below engine parameters:

I have also just checked David Culshaw and Peter Horrobin's The complete catalogue of British cars^[2] and it states 101 x 101 mm and 4,856 cc as well. I will see if I can find any other sources. Kind regards, Cavalryman (talk) 07:56, 30 January 2026 (UTC).

Apologies, I have just realised my typo in the article (made twice), I will fix it now. Cavalryman (talk) 09:20, 30 January 2026 (UTC)

Thanks - looking at other versions, I am prone to believing it 4"x4"; the 28HP had a 4 inch stroke (3 inch bore) and the 40HP had a 4 inch stroke (5 inch bore). Robson & Ware's other information does seem to have been copied from Bird. It's funny how these sources are exactly the same as WP - editors all copy, convert, round off, and reconvert figures and we end up with this sort of confusion. I can send you a scan of the Bird's tech page if you are interested. Best,  Mr.choppers | ✎  13:58, 30 January 2026 (UTC)

I would be very happy to return it to 4" bore & stroke, I suspect you are correct, this has been converted (possibly a couple of times back and forth). {{cvt|4|in|mm|0}} renders as 4 in (102 mm) whereas {{cvt|4|in|mm|1}} renders as 4 in (101.6 mm) and then all you need to do is overly aggressively round down to get to 101 mm. {{cvt|101|mm|in|order=flip|0}} might be a good compromise as it is correct by all sources but maintains imperial measurements first, which I think is appropriate for a British vehicle of that period.

I have found that judgement is often required when writing about vehicles of this period. Sources often contradict themselves slightly on minor details and then it becomes a matter of judgement as to whether it is appropriate to state in Wiki voice that contradictory sources exist, or to simply state in the article what is most likely the correct answer, or to omit that aspect altogether to avoid making a mistake. As better or more comprehensive sources become available, the article can always be amended.

Yes please, I would be interested to see a scan of what Bird says of the vehicle. My primary interest in this vehicle is regarding its military service, in particular as it relates to the Lanchester armoured car. So far I have not found a source that articulates how many were were produced during the war, were purchased by the War Office, or remained in service in 1918. Given Lanchester's other wartime commitments and the vehicle's primary service with the Royal Naval Air Service, I suspect it wasn't a huge number. Thank you again. Kind regards, Cavalryman (talk) 00:19, 31 January 2026 (UTC).

I found a scan HERE. I also realized that perhaps it doesn't matter a whole ton if this engine displaced 4856 or 4942cc... My guess is that Robson and Ware themselves wouldn't remember why they wrote 101mm either.  Mr.choppers | ✎  03:25, 31 January 2026 (UTC)

Thank you, and thank you for picking up my error, amazing attention to detail. I must have fumbled it in my mind then copied it between the text and infobox. Kind regards, Cavalryman (talk) 04:50, 31 January 2026 (UTC).