Graphics Development • Re: [OTTD] 2cc TrainsInNML

If you have all information about the locomotive you can actually compute the indicated horsepower using the PLAN formula:

Code:

P = mean effective pressure (psi)L = length of stroke (feet)A = area of piston (sq. inch)N = revolutions per minute (rpm)Power = (2*P*L*A*N) / 33,000 (hp)

In here, the length of the cylinder is 26" i.e. 2.166 feet, piston has diameter of 22" so area is 380, boiler pressure is 140 psi and its mean can be taken as 50% of that; only information we don't have is the revolutions per minute but it usually falls in the range 150 - 300 rpms, we can take 250 as a base value. The times two is because the locomotive has one piston on each side. With those, we get around:

Code:

Power = 2 * (140 * 0.5) * (26 / 12) * 380 * 250 / 33,000 = 873 hp

I got the explanation of the formula here.

Statistics: Posted by althonos — 24 May 2026 00:12