Stroller wrote: ↑Mon May 20, 2024 2:34 am
It seems two horsepower was claimed. Maybe they were Shetland ponies?
So when does air get drawn back in? Surely not during expansion, when there will be positive pressure??
Yep, near the end of the expansion stroke (see 1/2 dz lines under fig. 11). Hmmm, I doubt the guy who wrote this article saw this running. Overall, we're left to visualize operation via Vmax after expansion exceeds V prior compression similar a Miller cycle, but I think (1) the pressure swing will be too small within vintage temperature range, whereby (2) the rpm will be low due to meager pressure differential.
A lot of these old air engines look like converted steam engines. If any of these old buggers were ever made, and ran, I bet starting them was akin early low powered steam engines. My comment on the team of horses to spin up the flywheel relates to early large stationary steam engines which had a small auxiliary steam engine slowly spin up the flywheel while cycling steam thru the engine to preheat everything prior operation. These starters became known as "donkey engines" when mobile, and a single unit could start various larger stationary engines within a factory. Donkey engines became well known aboard ships (and logging) after large stationary steam engines had developed 'direct' starting thanks to higher pressure steam and clever valve schemes. My dad's first job was at a piano works where his primary task was running and maintaining the steam engine when 12 years old (nearly a century ago).
I used to own a big old teak built Royal Navy launch, fitted with a Glennifer 4 cyl 13 litre diesel engine. It started on compressed air. While the engine was running, you could switch a valve on No. 3 cyl to recompress air into the tank. If you failed to start the engine with the air next time, you had to compress it by hand with a big lever, which took muscle and time aplenty. It was nerve racking enough in port. I never stopped the engine while out on the water.
I own a "puny" portable sawmill that has a 1950's 13000 D8 Cat motor, diesel, that runs a 5' circular saw blade. It has a two cylinder gasoline/petral "pony" motor as the starting motor. It is both electric start and hand crank. The crank works better. Not sure why. Better spark I think. I wonder too if it is measured in pony power as well, it's a pony motor after all. LOL.
It has a "puny" off loading conveyor, log rollers, 10' minimum log carriage, hydraulic feed ramp/conveyor chain, and sawdust conveyor. But it's on wheels and is "portable".
I have a planer that is dated around 1900. To match it, with a growling 2 cycle Detroit diesel.
Fool wrote: ↑Tue May 21, 2024 12:32 pm
I own a "puny" portable sawmill that has a 1950's 13000 D8 Cat motor, diesel, that runs a 5' circular saw blade.
I have a planer that is dated around 1900. To match it, with a growling 2 cycle Detroit diesel.
Plenty of offcuts and sawdust for Stirling engine fuel then.
Stroller wrote: ↑Mon May 20, 2024 2:34 am
It seems two horsepower was claimed. Maybe they were Shetland ponies?
So when does air get drawn back in? Surely not during expansion, when there will be positive pressure??
Yep, near the end of the expansion stroke (see 1/2 dz lines under fig. 11). Hmmm, I doubt the guy who wrote this article saw this running. Overall, we're left to visualize operation via Vmax after expansion exceeds V prior compression similar a Miller cycle, but I think (1) the pressure swing will be too small within vintage temperature range, whereby (2) the rpm will be low due to meager pressure differential.
I will run some numbers, but looks plausible, if one takes this geometry to beta level due to removed extra dead space using valve. Plus i do realy like extra hot air movement while expansion.
