Alot of the casting kits are cast in fairly limited numbers like in the low hundreds at best. So if you see a kit available and think you maybe want to build it in the future buy the kit now. Seems like the 8" to 12 or so fly wheel dia.s run the nicest.
why people like low speed hit and miss engine?
- Thread starter Richard-Vanderpol
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Bentwings
Well-Known Member
are there really model hit and miss engines? I’d like to ad one to compliment the high tech model . I wonder if one could run on alcohol . I think it would need a massive Ky lead weighted flywheel with maybe weld mounted very near the outer edge of the flywheel . Tungsten is pretty heavy too but near impossible to machine I have about a pound of old Tig welding electrodes if you nick them with a diamond or carbide tool they break very well . Carbide is pretty heavy too and available in various pieces a tool shop might donate scrap tool bit inserts if you take nice to them . They could be brazed to the periphery pretty easily add a thin aluminum trim ring for beauty maybe double or triple flywheels possibly a gear train . Now you have me interested. There was one driving a water pump at the farm show that seemed it was about a hit per minute the guy sad it would run all day on about a cup of gas and another of water depending on sun light the flywheel must have weighed a ton it had a massive stroke and piston . I think the carb just pulled vapor from the open gas container very impressive machine .
Byron
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Bentwings
Well-Known Member
Well you got me going . I found about a dozen models some around $800 give or take eve Amazon has a couple very nice ones . I don’t like the idea of gasoline in the house. I don’t mind the Oder of fumes but my sister-Care giver would have a fit. So a couple things became apparent in reviews. Most have some kind of electronic ignition but a couple have magnets that seem to give trouble. So first alcohol is pretty order less fuel in engines. It requires high compression so power strokes could get noisy exhaust. Rather sharp actually , I don’t mine this. But I got thinking, why not steam or compressed air? I don’t think I have a good understanding of these yet I understand 4 stroke operation fine so ignition well glow plugs have been in models for a long time and readily available . You just need a battery but there are lithium ones and you could just leave it plugged in. So a good constant source of ignition is potentially available . If gasoline operated how about an activated charcoal exhaust container for exhaust even the same for venting the fuel can after all there are emission systems on cars even if you made a model catalytic converters I don’t think it would be practical as you would need external heating, not impossible but complicated . So I need some thoughts. I had kinda written this aspect out of the hobby. I’m not sur how you’d could do steam or compressed air. Some kind of injection system I think. I’ll give more thought to this later today
byron
coulsea
Well-Known Member
An interesting hit and miss engine that doesn't give off petrol fumes is the "Chuck Fellows" air/steam engine. Brian Rupnow built one and did up a set of plans. you can find them here https://www.homemodelenginemachinis...e-as-built-by-brian-rupnow.29267/#post-307097
Ohh.... I thought the "other" cycle was the Carnot cycle, or BI-cycle, tricycle, ...etc.
Note: The various Atkinson's cycles (at least 3 I think?) are all "suck-squeeze-bang-blow like the 4-stroke Otto and Carnot cycles, however, they accomplish this by linkages so the main shaft only rotates once per cycle. - Just like a ported 2-stroke, that combines the "intake-squeeze" into 1 half of crank rotation, and "bang-blow" into the second half of crank rotation.
Theoretically, the Atkinsons "cycle" is not a new combustion cycle, just a piston-motion alternative arrangement. It uses the Otto-cycle for the thermo-dynamic cycle, that Otto invented.
But never-the-less, Atkinson cycle engines, in the 3 mains forms (see Wiked-pedia) do have that "wierd" attraction when you watch them..! - Enjoy making one! - See other threads on this site!
K2
Note: The various Atkinson's cycles (at least 3 I think?) are all "suck-squeeze-bang-blow like the 4-stroke Otto and Carnot cycles, however, they accomplish this by linkages so the main shaft only rotates once per cycle. - Just like a ported 2-stroke, that combines the "intake-squeeze" into 1 half of crank rotation, and "bang-blow" into the second half of crank rotation.
Theoretically, the Atkinsons "cycle" is not a new combustion cycle, just a piston-motion alternative arrangement. It uses the Otto-cycle for the thermo-dynamic cycle, that Otto invented.
But never-the-less, Atkinson cycle engines, in the 3 mains forms (see Wiked-pedia) do have that "wierd" attraction when you watch them..! - Enjoy making one! - See other threads on this site!
K2
Perhaps I should explain some things about the Atkinson Differential engine's limitations.
The Engine is relatively Huge for the power output, compared to the Otto Engine, licenced to Crossley in the UK:
"Gas powered engines were developed in the 1860s by people searching for better ways to provide power and drive machines. Crossley became one of best known builders of gas engines in UK. Such engines were the answer to the industry’s need for small, simple and economic power units for small factories and workshops which could be used almost anywhere, and a range of sizes were produced."
This is due to a few simple facts:
The Atkinson Differential cycle uses a single cylinder, but moves 2 pistons alternately, and phased such that one piston does a large displacement for the compression and power strokes, but the second piston - with a shorter stroke - does the exhaust and Intake strokes. This shorter intake stroke limits the power compared to the Otto engine, that uses full length of the single piston stroke for the intake. This limitaion of inlet meant that the Atkinson engine was inherently larger than the Otto engine "for the same intake (fuel and air = power)". It was sold as an "economical" engine, and was very durable, because it was like an Otto engine never run at more than half power. - Which naturally extands durability and appears economical in the quantity of fuel burnt for its physical size...
Later Atkinson's (linkage cycles) used just a single piston, but again had a long stroke for compression and power but va short stroke for intake, thus limiting the charge available for engine (bore, stroke, crank and frame) size. - See Wiki for the details of Atkinson's 3 designs.
Stirling engines (external combustion) are interesting - and challenging - models, as an alternative to Otto cycle engines:
An abstract for anyone interested! (Carno versus Stirling)...
Hope something of interest gere (plus my usual errors!!??)
K2
The Engine is relatively Huge for the power output, compared to the Otto Engine, licenced to Crossley in the UK:
"Gas powered engines were developed in the 1860s by people searching for better ways to provide power and drive machines. Crossley became one of best known builders of gas engines in UK. Such engines were the answer to the industry’s need for small, simple and economic power units for small factories and workshops which could be used almost anywhere, and a range of sizes were produced."
This is due to a few simple facts:
The Atkinson Differential cycle uses a single cylinder, but moves 2 pistons alternately, and phased such that one piston does a large displacement for the compression and power strokes, but the second piston - with a shorter stroke - does the exhaust and Intake strokes. This shorter intake stroke limits the power compared to the Otto engine, that uses full length of the single piston stroke for the intake. This limitaion of inlet meant that the Atkinson engine was inherently larger than the Otto engine "for the same intake (fuel and air = power)". It was sold as an "economical" engine, and was very durable, because it was like an Otto engine never run at more than half power. - Which naturally extands durability and appears economical in the quantity of fuel burnt for its physical size...
Later Atkinson's (linkage cycles) used just a single piston, but again had a long stroke for compression and power but va short stroke for intake, thus limiting the charge available for engine (bore, stroke, crank and frame) size. - See Wiki for the details of Atkinson's 3 designs.
Stirling engines (external combustion) are interesting - and challenging - models, as an alternative to Otto cycle engines:
An abstract for anyone interested! (Carno versus Stirling)...
Hope something of interest gere (plus my usual errors!!??)
K2
I was reading through this thread, and noticed the comments on hit/miss governors. Regarding gas engines (in the UK sense coal-gas, now usually propane but there are some exceptions), on full-size units (which means anything from not-much-bigger-than-a-model, up to 18" bore 28" stroke, at our museum) the governor usually works on a valve which admits gas to the somewhat basic mixing chamber, which replaces a carb on a petrol engine. Larger ones tend to all be rotating-ball governors, which act on a fat shim which rides up and down, pulled by the balls as they rise and fall. This shim sides between a kind of 'pecker' which is operated by the cam which is meant to admit gas, and the gas valve itself. If the shim rides up (too fast) it is not 'there' to bridge the gap when the pecker comes forward, so the valve is not actuated, no gas is admitted, and speed falls. Inlet and exhaust valves just operate as normal all this time. There is often an air-start valve too, for compressed-air starting, on big ones, but modellers probably don't need to know about that!
On the way in the gas pipe goes through a simple conical tap. This is not a throttle - it controls the mixture, and basically determines whether the engine will run or not. If you want to go faster or slower you adjust the governor - which may mean messing with the gas tap too, to get the thing to run. These are single-speed engines, designed to run very slowly and economically producing a tiny amount of power (since such low speed) for their size, but to do so for decades on end (again, low speed means they don't wear out).
Smaller engines, and the ones I have seen this on are by Gardner, have an interesting and different arrangement. There the pecker (my term and a lousy one - I'm sure it has a real name) is flung forward by the cam but is free to rotate on a pin somewhere at its 'back' end. As soon as it starts to move it hits a peg which flings it up in the air, rotating around this pin - and then gravity starts to rotate it back down, all the while it is moving forwards towards the gas valve pushed by the cam. If the engine is going slow enough to need another 'bang', it will also be going slow enough to give time for the pecker to have fallen back into position before the assembly meets the gas valve - and gas is admitted. If the thing is to fast, the pecker is still on its way down when the assembly meets the valve, so the valve is not actuated and no bang occurs.
That's a pretty crappy explanation. It's easier when you stand and look at it!
Oh - the exceptions to running on propane are flame-licker vertical rack-and-pinion engines, where (I am told) the lack of hydrogen in propane as compared to coal-gas means the flame licker ignition does not work properly. So we run the engine on propane but the pilot light for the ignition, on hydrogen. This is a bit of a pain as the inspection regime for hydrogen stuff is a bit onerous here.
Design speed on a medium-sized one is typically only about 140rpm, and ticking over it will only fire every 3 or 4 cycles - on-load it will of course fire every time. Big flywheels will try to even the running speed out (and make running any faster, really dangerous!), but twins were increasingly employed as mill lighting went electric and the pulsing of the lightbulbs with the firing stroke was annoying. That itself was a change from the pulsing of gas lights with the firing stoke, due to the engine taking a big gulp of gas and dropping the pressure in the pipe. That was helped by rubber bags on the gas inlets near the engine, which act as a local reservoir or gas accumulator.
cheers
Mark
On the way in the gas pipe goes through a simple conical tap. This is not a throttle - it controls the mixture, and basically determines whether the engine will run or not. If you want to go faster or slower you adjust the governor - which may mean messing with the gas tap too, to get the thing to run. These are single-speed engines, designed to run very slowly and economically producing a tiny amount of power (since such low speed) for their size, but to do so for decades on end (again, low speed means they don't wear out).
Smaller engines, and the ones I have seen this on are by Gardner, have an interesting and different arrangement. There the pecker (my term and a lousy one - I'm sure it has a real name) is flung forward by the cam but is free to rotate on a pin somewhere at its 'back' end. As soon as it starts to move it hits a peg which flings it up in the air, rotating around this pin - and then gravity starts to rotate it back down, all the while it is moving forwards towards the gas valve pushed by the cam. If the engine is going slow enough to need another 'bang', it will also be going slow enough to give time for the pecker to have fallen back into position before the assembly meets the gas valve - and gas is admitted. If the thing is to fast, the pecker is still on its way down when the assembly meets the valve, so the valve is not actuated and no bang occurs.
That's a pretty crappy explanation. It's easier when you stand and look at it!
Oh - the exceptions to running on propane are flame-licker vertical rack-and-pinion engines, where (I am told) the lack of hydrogen in propane as compared to coal-gas means the flame licker ignition does not work properly. So we run the engine on propane but the pilot light for the ignition, on hydrogen. This is a bit of a pain as the inspection regime for hydrogen stuff is a bit onerous here.
Design speed on a medium-sized one is typically only about 140rpm, and ticking over it will only fire every 3 or 4 cycles - on-load it will of course fire every time. Big flywheels will try to even the running speed out (and make running any faster, really dangerous!), but twins were increasingly employed as mill lighting went electric and the pulsing of the lightbulbs with the firing stroke was annoying. That itself was a change from the pulsing of gas lights with the firing stoke, due to the engine taking a big gulp of gas and dropping the pressure in the pipe. That was helped by rubber bags on the gas inlets near the engine, which act as a local reservoir or gas accumulator.
cheers
Mark
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Hi Piston,
I think you only touch on one aspect here - a reasonably well made IC engine will run happily at "low speed" (whatever your personal definition of this term may be) as long as the mixture, ignition timing, cam profiles, valve timing, fuel type, etc, etc are all apropriately selected too. Precision is not required in any way shape or form in a "one off" engine, but good "fitting", and possibly accuracy, is.
Al the best,
Ian
(Sorry to double-post, but this might be interesting. Think about an older British car engine - say something like a Morris Minor (BMC A-series) which would have been pretty much shagged by 100k miles. At least, mine was! If the average speed is say 25mph - mostly running around town, a few longer trips) this is a life of 4000 hours, which is a bit less than 6 months! That's why low-speed engines are a big deal, where they are (and the clue is in the name) stationary, so moving their huge bulk around is not an issue - the run-time between servicing is orders-of-magnitude better than on the sort of engine we are used to looking at on vehicles).
Hi Mark, A good clear explanation. But just an odd point... I understand that many engines have the "pecker" (your term) in the valve trian to the inlet valve, so the inlet valve is only operated when slow enough. But if there is only an exhaust valve - and using a "demand" or automatic inlet valve, then either way there is no connection to the gas valve..?
Incidentally, on my Atmospheric gas engine, I have fitted an acetylene generator, as that has the appropriate Hydrogen ignition properties as per coal gas. (Cavers and pot-holers still use modern acetylene gas generators for lighting...).
https://caves.org/member/mfraley/intro.htmK2
Incidentally, on my Atmospheric gas engine, I have fitted an acetylene generator, as that has the appropriate Hydrogen ignition properties as per coal gas. (Cavers and pot-holers still use modern acetylene gas generators for lighting...).
https://caves.org/member/mfraley/intro.htmK2
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That's interesting. My boss is / was a caver, and told me that getting hold of the stuff for carbide lamps was more tricky now LED lamps have taken over underground. How do you find it?
That's a nice Crossley gas engine. Thinking about it, the ones I am most familiar with at our museum are by National and Gardner, whose systems I have described above. The Nationals have a low-tension 'magneto' on rather like your pic - operating a pair of heavy-duty contact points in the combustion chamber itself, at which the spark appears. The linkage is really horrible and rattly!
There are several engines at our museum with automatic inlets, but I am not familiar with them - I'll have to have a closer look. I'm also more sketchy on governors for hot-bulb and early diesel engines - I had to look closely at your pic for a minute as we have a National diesel in a display which looks very similar!
Here's a video of our museum someone put up - you might be able to see some of the stuff I was trying to describe.
That's a nice Crossley gas engine. Thinking about it, the ones I am most familiar with at our museum are by National and Gardner, whose systems I have described above. The Nationals have a low-tension 'magneto' on rather like your pic - operating a pair of heavy-duty contact points in the combustion chamber itself, at which the spark appears. The linkage is really horrible and rattly!
There are several engines at our museum with automatic inlets, but I am not familiar with them - I'll have to have a closer look. I'm also more sketchy on governors for hot-bulb and early diesel engines - I had to look closely at your pic for a minute as we have a National diesel in a display which looks very similar!
Here's a video of our museum someone put up - you might be able to see some of the stuff I was trying to describe.
Rocket Man
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Large diameter flywheels have more inertia than small diameter flywheels that makes large flywheel engines much easier to run very slow when comparing a group of engines of the same, mass, same HP, same friction.
mark are you confusing Flame licker and flame ignition engines?
A flame licker draws in a large flame and it is the condension of the cooling flame that pulls the piston giving power. It sound like you are talking about flame ignition where a pilot flame lights a carrier flame and that is drawn into the combustion chamber to ignite the air/gas mixture.
The I F Allman engine that I built has the governor linked to the gas inlet valve via a series of links and cranks from the governor weights.
The "Pecker" governor you mention is known as an inertia governor, probably doing one of those on a "Penultimate" that I'm likely to build next year
A flame licker draws in a large flame and it is the condension of the cooling flame that pulls the piston giving power. It sound like you are talking about flame ignition where a pilot flame lights a carrier flame and that is drawn into the combustion chamber to ignite the air/gas mixture.
The I F Allman engine that I built has the governor linked to the gas inlet valve via a series of links and cranks from the governor weights.
The "Pecker" governor you mention is known as an inertia governor, probably doing one of those on a "Penultimate" that I'm likely to build next year
Bentwings
Well-Known Member
Thanks I looked at the site as well as others one did have electronic ignition single cyl on alcohol
byron
I looked at the model engines available and found a lot of them . Size affects them as they generally have dual flywheels there is a cool fly ball throttle available just to add more moving parts. Most are variants on 4 stroke design . Some have electronic ignition and a few had magneto ignition most of these seem to have starting issues where the electronic ones start pretty easy . I think it would be easy to control ignition so they would actually mis fire just to slow them down I thought of using a glow plug and a small generator to keep a lithium battery charge for glow operation . These models aren’t cheap but are great looking desk top models I did fine one that runs on alcohol so it would not stink so bad . Along the same line I looked into various oils. Steam oil is not available locally . But model car silicone oils are in the hobby shops. Also rediscovered Klotzoils I used to use thes for my giant scale Rc planes in gasoline. Going back many years they had castor oil too that I used in glow engine. They still have it but mail order . One bike shop reportable has it for motor bike racers. Castor oil is relatively removable with alcohol and soap as water. Still messy if baked on . I ran into some highly technical writing about castor oil. It was go to oil for aircraft and autos for a long time actually canola oil is an ok substitute. I had a diesel pickup during the early days as biodiesel was developed. Diesel fuel got real expensive and wasn’t available at al some times I raided the grocery sores for canola oil a number of times. It was expensive but cheaper than pump if you could find I’d diesel at all . Gotta go to work every day some how . Anyway I’m back to building a steam boiler copper is totally out of this world for price. Right up there with unobtainium .
Byron
Hi Mark, I can see why you call the Gardner inertia governor a pecker! I am more used to seeing flywheel inertia bob weights activating a linkage affecting the gap or not in the push rod or lever between cam and valve.
K2
K2
I'm about ready to dish $600 for a hit and miss that doesn't run (~4hp). I could sleep all day to that sound....with nothing hooked up of course. Am I the only one here that binge-watched through the entire RedRyder hit and miss playlist on youtubes? (I did, hehe).
Zeb, the Human head can switch off and sleep anywhere. When in the Navy, we had the rotary converter in the mess - it supplied AC power for the radar from the ship's DC... - A Very Loud and constant drone. I never missed a wink of sleep, day or night, until the radar was powered off at sea once... while I was off-watch examining the inside of my eyelids. (Bunk study). The main engines were still throbbing, and ship moving (not that you noticed after the sea-legs were fitted) and blokes moving arouns the mess. But the running down drone of the radar DC-AC converter (took maybe 1 minute?) was an instant alarm!
K2
K2
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