Oddball engines and prototypes

[WilDun]

My door stop could be handy for one of those:

That's pure sacrilege! - All CI I bet? - Could I have it for my next project? If you dug the concrete and rust from around the rings & grooves and with a bit of CRC, it might be a goer! - failing that,I could use it for material for my lathe.
Seriously, I can see it's for a two stroke, but what two stroke?

[XF650]

That's pure sacrilege! - All CI I bet? - Could I have it for my next project? If you dug the concrete and rust from around the rings & grooves and with a bit of CRC, it might be a goer! - failing that,I could use it for material for my lathe.
Seriously, I can see it's for a two stroke, but what two stroke?

Found it under some trees on in-laws farm & its bloody heavy - probably out of a Lanz Bulldog.

[unstuck]

probably out of a Lanz Bulldog.

Hot bulb engine?

[WilDun]

Yes, I think the Poms pinched the Lanz Bulldog design at the end of the war and modified it into the Field Marshal, but then they turned it into an injected diesel and consequently didn't use the deflector piston anymore because of the higher compression required (they probably used the Schneurle scavenging system with a flat top or domed piston). Well that's what I was told a long time ago but who knows!
Very hard to find any info on these engines - somebody here might know where to find it.

EDIT.
It appears that Field Marshall had acquired a couple of Lanz Bulldogs in the late twenties to study and it was then that they decided to build a diesel engined 'lookalike' of the very popular Lanz, this early diesel went into production around 1930, - so really nothing to do with the war!

[unstuck]

..................

[husaberg]

Angus Cuddon-Fletcher
I can't find the engine he did with a water cooled rotary valve, that I am I am looking for to post. But he was sure prolific with some of his other ideas.

Angus Humphrey Cuddon-Fletcher (GB)
3 Jul 1909 - 1973/74?Born in Dunans, Argyll, Cuddon-Fletcher was a designer engineer. Among other things he worked on a rotary engine, which he sadly failed to patent. He took part in racing before the Second World War, racing MGs at Donington, Crystal Palace & Brooklands. There was at some stage a kind of partnership with Reg Parnell. He emigrated to the United States in December 1965 and remained in the field of (Marine) engineering. Died in in Wisconsin in the 1970s.
(Info supplied by Susan Cuddon-Fletcher)

[husaberg]

Ferrari trialled them for f1 Mazda used them on a production diesel, Yet I have never heard of them.
Comprex Pressure Wave Supercharger or
Pressure wave supercharger

Comprex Pressure Wave Supercharger consists of a synchronized belt-driven, cell-type compressor wheel (1), fed on one side by an ambient intake duct (2), and discharging compressed air into the intake manifold (3). On the exhaust side, the high-pressure exhaust from the exhaust manifold feeds through the duct (4), and is expelled-at lower pressures-into the tailpipe (5).
Sometime back when I was perusing the Bosch Automotive bible looking up compressor maps for positive displacement superchargers, I came upon the rather odd image below. It's called a Comprex, something like a hybrid mutant of a turbo and a supercharger, but better than both-at least in theory.
While not a new invention, we don't really see much of the Comprex, since it's mainly used in large marine and earth-moving diesel engines and, in some cases, smaller passenger car applications. But my interest was piqued by the fact that the Ferrari Formula One team played with a Comprex on their early-80s turbo cars, with better results than conventional turbocharging.
Officially called the Pressure Wave Supercharger, a Comprex is basically a stationary drum casing with a lost-wax cast straight-vane rotor spinning inside the drum, creating boost. Think of it as a wide water wheel inside a drum.
Like a turbo, the casing and rotor aren't in contact, but the clearance between the two is kept to a minimum (barring thermal expansion and creep) to prevent boost leakage. The synchronized belt-driven rotor is powered by the crank, moving around four to five times faster than the engine, but only drawing enough to overcome the frictional losses of the assembly. This means the Comprex doesn't suck power away from the engine to do the work of compression. The compression is done by the exhaust gases like a turbo, which is essentially free energy.
So if you're not using the engine to compress air like a supercharger and not driving the rotating assembly with exhaust gases like a turbo, what is doing the compressing? This is where the 'pressure wave' portion of the name comes in. Incoming ambient air is compressed by using the pressure wave from the exhaust gas.


The production Comprex unit used on the 2.0-liter diesel Mazda 626 Capella.


Each end of the drum has two different-sized ports, connected by ducts for air or exhaust gas to enter and exit. On one side of the drum, air enters from the intake at near-ambient pressure and exits at boost pressure to the intake manifold, while on the other side, exhaust gas from the exhaust manifold enters at high pressure and exits to the tailpipe at lower pressures. How compression is done is the hard part to explain.
The process starts as a given channel on the rotor already filled with ambient intake air (I'll tell you how it's filled later). Neither end of this channel is lined up with a port, so it's completely sealed off by each end of the drum. As the drum rotates, the port on the right side, a smaller high-pressure exhaust orifice, is exposed first to let in the just-combusted gases, which introduces a compression or shock wave into the channel. The shock wave propagates at the localized speed of sound and pushes fresh air against the left wall of the drum, which is still closed and thus compressing the charge. These compression waves are not on account of the individual pulses of each cylinder firing, just the rapid introduction of two gases at different pressures.
As the charge compresses, it makes space, allowing the exhaust gas to enter the channel. Since the shock wave is traveling so fast, the two gases never mix. By this point, the channel has rotated to the high-pressure air port leading to the intake manifold. Although rated for the same mass flow rate, the smaller port is sized so that the compressed air exits at a much lower velocity. This deceleration of the compressed air causes a secondary shock wave to propagate toward the right (or exhaust) side, which compresses the fresh air further. This way, the boosted air going into the engine is actually at a higher pressure than the exhaust gases.
As this secondary compression wave reaches the right side of the drum, the high-pressure gas port closes, causing the compression wave to reflect back as an expansion wave, pushing most of the compressed air out and closing that port. By now, the low-pressure exhaust port on the right is exposed, letting the now slightly pressurized exhaust out into the tailpipe. This causes another series of expansion and compression waves that ultimately help pull in and completely fill the channel with fresh air, which brings us back to step one.




The Comprex blower combines the best of both worlds. The Comprex is both exhaust gas and belt driven. It uses the belt off the crank to keep boost constant and uses the hot exhaust gas to spin the vanes inside the blower, while drawing in cold outside air. Unlike a turbo though, it reuses the exhaust gas, some of it at least. So if you run the engine nice and rich, you can reburn the unspent fuel after it has been compressed: "Because the Comprex vanes only act to distribute gases, not push them, power is only needed to overcome friction of the rotating parts. Now, take a model piston engine. Let it spin a small Comprex blower which blows into a ramjet-type combustor. There you have a simple hybrid jet engine that would work at very low and very high air speeds relatively happily. You would just have to juggle the engine/blower/combustor dimensions carefully so that the engine is just big enough to do its job, and does not produce surplus shaft power. There's more. Bleed some of the compressed air back to the piston engine to boost its power, so that you can use a small engine to turn a relatively big blower. (Comprex can spin at very high speeds as its vanes are of small diameter.) Properly, you should run the engine as rich as it will take. After it has done the job of compressing air, exhaust gas is ejected into the ramjet/combustor, where it mixes with fresh air coming from the compressor. As it is still rich with unburned fuel, it only combusts properly in the ramjet. Fuel is injected into the combustor just to top the mixture up so to say. This way, because of recirculation, you also get a relatively clean exhaust. Sounds complex, but need not be complex in practice. Similar hybrids have worked really well in the past. Perhaps the most complex in history was the 12-cylinder 2-stroke (!) supercharged aircraft diesel (!) engine built by Napier in the (I think) early 60s. It burned super-rich mixture and blew its exhaust gas into combustors of a small turboshaft. More fuel was injected here and the resulting hot gas drove a turbine, which turned an axial compressor, which blew both into the 12-cylinder piston engine and into the combustors of the turboshaft. The two output shafts (of the piston engine and the turboshaft) were geared together to turn a single output shaft, which turned the aircraft propeller. It sounds incredibly complex but worked very well indeed and was a very fuel-efficient engine by the standards of the times. Keith Duckworth, the constructor of the most successful car racing engine of all times, the Cosworth V8, proposed the same layout for Formula 1 back in the days of turbocharged F1 engines. He said it was the most logical extension of the turbocharged piston engine

http://en.wikipedia.org/wiki/Pressure_wave_supercharger

[unstuck]

double dutch

Gonna have to get my bro to translate that one for me.

[husaberg]

Gonna have to get my bro to translate that one for me.

Does he share genetics with you?

The thing spins to allow the vanes to line up with ports that allow the exhaust gas to leave, and fresh air to be drawn in. There is no turbine (like on a turbo), and the compression isn't being driven by the belt/pulley (as on a supercharger)...the rotor is not spun to generate compression, it's spun to allow fresh air to enter the vanes, and exhaust gas to exit. It's acting more as a "gatekeeper" than anything.

In other words, the thing wouldn't work at all, at any speed, without the belt driving it, but the amount of work the belt does is minimal (just frictional losses).
cake and eat it too, Only issue is the intermingling of ex and fresh charge which is why its better on a diesel........

This Comprex or Pressure-Wave Supercharger is a very simple device in comparison to a turbo or roots-type blower. Having very few parts the Comprex consists of a cylindrical chamber which contains a belt-driven bladed ‘wheel’ and two ports offset from one another on each end. Through those ports ambient air enters and exits on one side and hot exhaust gases enter and exit on the other side. Though it’s construction is very basic, understanding how a pressure-wave supercharger works may not be as simple for some. The single most confusing aspect of this is that physically there is nothing that separates the intake air from the exhaust once inside the compressor, yet only very small amounts of exhaust gases ever return to the cylinder. To better understand how this process works here is a step by step.

First air is drawn into the cylinder like any other internal combustion engine by the downward movement of the piston, and with the Comprex in it’s path the air naturally must pass through it first. Inside the compressor air is turned and the blades are moved past the ports on either end of the chamber. When hot exhaust gases enter the chamber it is at a much higher pressure than that of the air that is already in the Comprex which in turn starts a pressure equalization process. When two compressible mediums change state they change by means of pressure waves. So when each blade passes by the exhaust inlet port air enters that cell (the area between each of the blades) and send a pressure wave towards the intake air at the speed of sound. Now for the tricky part. Since the wheel is turning perpendicular to the movement of the pressure waves and with the help of physics the waves then move in a slanting motion towards the other end of cell, compressing the intake air (which is at atmospheric pressure) to the pressure level of the expanding exhaust gases. The exhaust gas then follows the pressure wave at a much lower velocity. The ports are designed with the timing and speed of the pressure waves factored in so that the wave reaches the intake side at the exact instant the blade passes the leading edge of the outlet or “charge port” leading to the combustion chamber.

Due to the timing of the first pressure wave and the escaping charged intake air a second pressure wave is created which then flows back towards the exhaust side. This compresses the air within the cell again while also slowing it down. By the time the second wave reaches the other side the exhaust port has been passed and the air then has nowhere to go. At this point the charge air port is still open, and because of inertia the exhaust gases are still flowing towards the intake side regardless of the counter pressure wave. Because of this a new element enters the equation: expansion waves. An expansion wave is formed and slows the cell contents down considerably, decreasing pressure in that cell.

Once the wheel has come around to the exhaust exit port yet another expansion wave is created due to the now different pressures inside and outside of the cell. The wave flows towards the intake side, lowering the cell’s pressure and accelerating the air out of the cell and into the exhaust system. This final wave is strong enough to fully evacuate the cell and draw in enough air to completely fill that cell with fresh air. Then, of course, the process repeats. This complete process happens twice per revolution of the wheel and only takes place over the span of three to six milliseconds. However if certain conditions aren’t met and the timing of this process is not tuned perfectly the pressure waves will deteriorate rapidly. Never the less this idea of forced induction could possibly find it’s way under the hoods of production cars one day. Not only is it a very light draw on the engine itself, but NOx gases are partially re-circulated and used to create more energy for the engine. Now if somebody could just apply this technology to performance cars…

This compressor uses exhaust pulses to compress the
intake air, but has a belt driven rotor that must be
timed to the engine. Intake air goes in than the
intake is sealed, then the exhaust side is opened
and exhaust gasses enter the same cavity as the
fresh intake charge compressing it. Then the intake
opens and the compressed intake exits toward the
engine, the intake port is then closed off before the
exhaust has a chance to get in the intake.

[unstuck]

Does he share genetics with you?

Yeah, but he speaks dutch, and that video sounded dutch to me.

[husaberg]

Yeah, but he speaks dutch, and that video sounded dutch to me.

I'd plum for German as its Swiss it think?
the pics are all in English though

[unstuck]

I'd plum for German as its Swiss it think?
the pics are all in English though

Dunno, but I'd like to be able to understand what the dude was saying. Im funny like that.

[WilDun]

I'd plum for German as its Swiss it think?
the pics are all in English though

Doesn't matter - we don't understand it anyway whatever it is! and I for one still don't even understand the concept (probably Swiss German)

[unstuck]

and I for one still don't even understand the concept

I think I kinda do, but seems to me that the air going in could potentially get slightly heated. But then I could have it completely wrong too.

[WilDun]

Back to bikes, - then there was the 1939 Velocette 500cc contra-rotating twin, with a fore & aft crankshafts, which they nicknamed the 'Roarer'.
It had a lot of potential, but this was cut short when the war broke out. :-



http://velocette-amateur.com/roarer_engine_en.htm