Wheellocks and Flintlocks

[Varyon]

Originally Posted by johndallman

I'm rather dubious about this. You're requiring the lock to do a lot more mechanical work than a flintlock or wheellock. Springs were some of the hard parts of those locks, and this is going to need stronger ones, which start to require real effort to cock. As for the ratchet for the piston - you're creating something approaching the ambition of a semi-automatic action, in an era of much worse materials, with everything made by hand. It's going to be expensive, dangerous, or both.

I misspoke (err, miswrote) when I wrote "ratchet." You wouldn't need anything nearly so advanced - a simple catch as is used to hold a crossbow string or similar should be sufficient. The trick would be to have it in the correct location (note that the piston coming back out isn't in and of itself a serious concern - rather, there's the risk of it coming back out with sufficient force that it breaks free, which will cause you to vent pressure rather than propelling your bullet).

I've been doing a bit of research on fire pistons. First off, you can determine what temperature (in Celsius, assuming the ambient temperature is around 27 degrees - note it doesn't change too much for lower starting temperatures) the tender inside will reach based on the equation T=300*(Li/Lf)^(2/5)-273, where T is the temperature, Li is the initial length of the cylinder of air in the piston and Lf is the final length of the cylinder of air in the piston. I can't find the blasted "Semenov equation"/relationship that nearly every paper references, but apparently autoignition temperature (that is, the temperature at which an object ignites without the presence of an open flame/spark) actually decreases as pressure increases.

Black powder has an autoignition temperature between 200C and 464C. Nitrocellulose apparently has an autoignition temperature around 220C, as does paper (putting a scrap of paper in with your black powder shouldn't be too difficult, so we'll assume 220C is the autoignition temperature of both propellants). So, 220=300*(Li/Lf)^(2/5)-273, or Li/Lf=3.5 (so we need around 70% compression). That's at 27C (80F) - 0C (32F) is going to be Li/Lf=4.4 (~78% compression). This ignores (because, as noted, I couldn't find the blasted equation) the effect of pressure on autoignition - you could probably get away with much less compression.

Regardless, you apparently only need compression of around 80% (5:1), while traditional fire pistons apparently tend to have a compression of around 96% (25:1), yet can be started with a simple slap. It seems that getting a spark out of flint and steel requires comparable force, and detonating mercury fulminate probably isn't far off, so I'd imagine the same springs that store enough force for flintlocks to work would suffice in detonating a fire piston powered firearm.

Originally Posted by Sindri

If wheellocks don't have a significant downside for the wealthy all that is necessary for their continued presence is for it to be plausible for them to have grown attached to them given the right circumstances.

Indeed. Probably the biggest thing that prevented this in our history was that there was only about a 40 year window between the wheellock and the snaplock being produced. That's really not enough time for wheellocks to become ingrained as a "noble's weapon." If there were 100 or more years between the two, you might have ended up with wheellocks gaining such status.

Originally Posted by malloyd

Sure there is. Time for a hammer to fall certainly can differ from time until the wheel is fast enough to throw sparks.

There's also the fact that apparently the wheel produced sparks in much closer proximity to the pan than the hammer did - no need to wait for them to fall before the powder gets ignited. It's not really enough to be tactically significant, however.