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Modern jet aircraft wings (commercial airliners) are incredibly flexible, and yet very strong.

I suppose a rigid wing would soon crack.

Strong, but not rigid.
Yeah, same goes for repairs that are too stiff. Loads will concentrate instead of dumping smoothly through the structure. Even the magic puters can't calculate and predict with the accuracy that fatigue and ultimate test articles can provide.
 
Ladies and Scholars,
I just finished reading the porn "Eye of the Needle" by the famous British author, Ken Follet. In this porn, a 1924 Morris Cowley Bullnose was used by the badguy, stolen from two old ladies. This engine was 1548 cc side valve. Being a gasoline engine, does anyone know what a "side valve" is? Has anyone heard of this engine?

The porn is a WWII spy novel, I find Ken Follet to be an EXCELLENT author.

Everyone named "Ken" should respond.

P.S. I did find one of Follet's porns to be awful, but only one.
A side valve (flat head) engine is an engine is where the camshaft and crankshaft is both at the bottom of the engine block, the valves are also fitted in the engine block and the cylinder head is flat with the sparkplugs standing upright in the cylinder head. Search the internet for either side valve or flathead engine for a picture.
 
Ihe inlet and exhaust valves are inserted into the engine block beside the cylinders, not in the cylinder head as in an overhead valve engine.
 
Ladies and Scholars,
I just finished reading the porn "Eye of the Needle" by the famous British author, Ken Follet. In this porn, a 1924 Morris Cowley Bullnose was used by the badguy, stolen from two old ladies. This engine was 1548 cc side valve. Being a gasoline engine, does anyone know what a "side valve" is? Has anyone heard of this engine?

The porn is a WWII spy novel, I find Ken Follet to be an EXCELLENT author.

Everyone named "Ken" should respond.

P.S. I did find one of Follet's porns to be awful, but only one.
It's the same as you Americans call a flathead, valves in the block. Another one to add to the English to American translation list 😁
 
As a Ken I felt obliged to respond. Not being a reader of Porn I have not read this from Ken Follet.... by searching the web found this on the car.
https://nationalmotormuseum.org.uk/vehicle-collection/morris-cowley-bullnose/https://classicandsportscar.ltd.uk/...-2-seater-with-dickey/classic-cars-sold/62365The Side-valve engine was the precursor of the Overhead valve engine. - The configuration used mostly today.
Overhead valve engines use valves mounted in the cylinder head, along with the ports for inlet and exhaust and valve gear to operate the valves, This needs a mechanical drive from crankshaft to cylinder head to operate the valve gear.
Earlier engines were much simpler.
The valves were on the side of the engine cylinders. Hence Side Valve.
https://en.m.wikipedia.org/wiki/File:Side-valve_engine_with_Ricardo's_turbulent_head_01.png
1696570795214.png

The camshaft was at the bottom of the engine, next to the crankshaft, and drove valves that were mounted in the cylinder block directly. The inlet and exhaust ports were in the cylinder block. The passages from valves to cylinder were shaped from the cylinder head and face of cylinder block. The combustion chamber was inevitably a flat thing, not unlike your hand placed flat on a table top with a Vee-formed between your middle fingers. 2 fingers were the passage for inlet, 2 for exhaust.
https://www.google.com/search?q=sid...ient=gws-wiz-serp#vhid=hM6Kmm6w6teLMM&vssid=lThis was a very poor combustion chamber by comparison with the more complicated overhead valve engine.
https://www.google.com/search?q=ove...CBgeGA3iAwQYACBBiAYBkAYI&sclient=gws-wiz-serpAn ideal combustion chamber would be spherical at bottom dead centre. - But almost impossible to make!

Hope this helps?
K2
 
As a Ken I felt obliged to respond. Not being a reader of Porn I have not read this from Ken Follet.... by searching the web found this on the car.
https://nationalmotormuseum.org.uk/vehicle-collection/morris-cowley-bullnose/https://classicandsportscar.ltd.uk/...-2-seater-with-dickey/classic-cars-sold/62365The Side-valve engine was the precursor of the Overhead valve engine. - The configuration used mostly today.
Overhead valve engines use valves mounted in the cylinder head, along with the ports for inlet and exhaust and valve gear to operate the valves, This needs a mechanical drive from crankshaft to cylinder head to operate the valve gear.
Earlier engines were much simpler.
The valves were on the side of the engine cylinders. Hence Side Valve.
https://en.m.wikipedia.org/wiki/File:Side-valve_engine_with_Ricardo's_turbulent_head_01.pngView attachment 150389
The camshaft was at the bottom of the engine, next to the crankshaft, and drove valves that were mounted in the cylinder block directly. The inlet and exhaust ports were in the cylinder block. The passages from valves to cylinder were shaped from the cylinder head and face of cylinder block. The combustion chamber was inevitably a flat thing, not unlike your hand placed flat on a table top with a Vee-formed between your middle fingers. 2 fingers were the passage for inlet, 2 for exhaust.
https://www.google.com/search?q=sid...ient=gws-wiz-serp#vhid=hM6Kmm6w6teLMM&vssid=lThis was a very poor combustion chamber by comparison with the more complicated overhead valve engine.
https://www.google.com/search?q=ove...CBgeGA3iAwQYACBBiAYBkAYI&sclient=gws-wiz-serpAn ideal combustion chamber would be spherical at bottom dead centre. - But almost impossible to make!

Hope this helps?
K2
Whoa, learn something old every day! Thanx for those linx. I expected that car to be something short and square but it is long and sleek. I likes that.
 
Most European regular motorcycles and cars up to the 1930s were side-valve. Then overhead valve engines replaced them (often on the same crank, and bottom end) until by around 1950. But in the USA Harley Davidson continued with lower powered motor cycle engines with side valves and low compression until well into the 1960s. Nick-named "Hardly-able-tons" by many as a result. Discerning people - like James Dean, Elvis, Steve McQueen, Evel Knevl, n all bought imported Triumph overhead valve bikes in the 1950 for the speed and excitement avaliable from the better and lighter OHV engines.
K2
 
Most European regular motorcycles and cars up to the 1930s were side-valve. Then overhead valve engines replaced them (often on the same crank, and bottom end) until by around 1950. But in the USA Harley Davidson continued with lower powered motor cycle engines with side valves and low compression until well into the 1960s. Nick-named "Hardly-able-tons" by many as a result. Discerning people - like James Dean, Elvis, Steve McQueen, Evel Knevl, n all bought imported Triumph overhead valve bikes in the 1950 for the speed and excitement avaliable from the better and lighter OHV engines.
K2
So exactly how does the overhead create more power?
 
Having the valves in the block requires more space and limits the compression ratio. By moving them to the head directly above the piston you also have less exposed metal that is robbing the engine of heat. The higher the compression and the higher the temperature the engine can run at, the higher the power to weight ratio.
 
A big drawback with a flat head is the valves are closely adjacent so any valve timing overlap is problematic because the new fuel charge exists from the intake out the exhaust before the valves close.. Also much larger valves are possible with overhead valves. Overhead designs allow the exhaust and intake manifolds/ports to be on opposite sides of the head allowing better flow and not as hard to keep the carb cool. Etc.
 
So exactly how does the overhead create more power?
It allows for a higher compression ratio due to the geometry. And of course the greater the compression ratio the more power you get until detonation occurs and then the engine becomes a diesel. There are equations that prove these concepts. However, higher compression comes with a very important criteria that the heat on the cylinder walls and head is removed.
 
On heat flow, the heat losses to the piston and cylinder head need to be minimised as it is "wasted fuel". Also, the CO combustion stops around 320deg C so as the gases approach "colder" metal the fuel becomes unburned due to expansion and cooling. This is more wasted fuel. The "perfect" combustion chamber is a sphere, that minimises surface area to volume ratio. The Side valve engine is more like a flattened
lump of clay, I.E. 2 large areas close to each other, somewhat akin to a flat hand, not a fist. This large surface area actually reduces the combustion of some of the fuel-air charge, so reducing the power compared to the overhead valve combustion chamber using the same mass of fuel and air. More fuel-air unburned in the cylinder is less power for the crankshaft, and more stuff to burn when mixed in the exhaust pipe and more pollution. Many factors involved!
K2
 
Having the valves in the block requires more space and limits the compression ratio. By moving them to the head directly above the piston you also have less exposed metal that is robbing the engine of heat. The higher the compression and the higher the temperature the engine can run at, the higher the power to weight ratio.
And this can be proved mathematically using thermodynamics that the efficiency is directly proportional to the compression ratio. The first Ford V8 were called flatheads and you could plain the head down to increase the compression ratio. But they were finally beat out on the race track with the short block Chevy V8 --a fun time for hot rodders
 
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