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Ratsack
04-07-2008, 01:45 AM
Now here's a poser.

If you have an Me 109 G equipped with nitrous oxide injection, this installation would provide extra power. It does it by making extra oxygen available, meaning that the engine can burn more fuel, and so produce more power.

Two problems that might occur with this device are fuel delivery, and cooling. If you are going to burn more fuel, you will need to get it to the chamber, and this may be beyond the capability of your existing fuel pump. You might need a bigger pump. Similarly, if you're going to burn more fuel, you're going to produce more heat, and this may be beyond the capability of your existing cooling system to cope with. You might need bigger radiators and a bigger water pump.

However, if you only operate the system above full throttle height (FTH), then you probably don't need a new cooling system or fuel pump. Above FTH, the supercharger can no longer maintain maximum manifold pressure. This is the pressure at which the motor would normally be delivering and burning maximum fuel, and producing maximum heat. Above that height, the manifold pressure would normally decrease with altitude, and the amount of fuel delivered would decrease too. However, with NO2, you could maintain the fuel delivery at the rate you use at FTH, and provide enough NO2 to make up for the thinner air. So your engine is producing FTH power above FTH, and the existing fuel pump and cooling will probably suffice within reason. In addition, NO2 under pressure would initially have a cooling effect in the inlet manifold.

In contrast, water methanol works by cooling the charge and so preventing pre-detonation at higher manifold pressures than can normally be used. The higher manifold pressure is achieved by running the supercharger harder, thus cramming more air into the chamber, thus allowing more fuel to be burned and thus producing more power. The neat bit, and the bit where the water comes in, is that the water sprayed into the charge in the inlet manifold cools it and prevents it from pre-detonating (˜pinging' or ˜knocking' for the petrol heads). Because this system relies on the supercharger to produce extra manifold pressure, this system only produces extra power below FTH, although presumably it would produce extra cooling above FTH.

Looking at the elements of the system, it requires that the supercharger run at a higher speed in order produce the higher manifold pressure. It also requires that more fuel is delivered to take advantage of all that extra air shoved into the chamber. This means you would have to do something to your supercharger governor, and you'd probably need a new fuel pump (or perhaps changes to the settings of the existing one?).


So it seems to me that you would need to do some important modifications to your motor if you wanted to change from NO2 to water methanol, but less if you wanted to change the other way.


cheers,
Ratsack

Ratsack
04-07-2008, 01:45 AM
Now here's a poser.

If you have an Me 109 G equipped with nitrous oxide injection, this installation would provide extra power. It does it by making extra oxygen available, meaning that the engine can burn more fuel, and so produce more power.

Two problems that might occur with this device are fuel delivery, and cooling. If you are going to burn more fuel, you will need to get it to the chamber, and this may be beyond the capability of your existing fuel pump. You might need a bigger pump. Similarly, if you're going to burn more fuel, you're going to produce more heat, and this may be beyond the capability of your existing cooling system to cope with. You might need bigger radiators and a bigger water pump.

However, if you only operate the system above full throttle height (FTH), then you probably don't need a new cooling system or fuel pump. Above FTH, the supercharger can no longer maintain maximum manifold pressure. This is the pressure at which the motor would normally be delivering and burning maximum fuel, and producing maximum heat. Above that height, the manifold pressure would normally decrease with altitude, and the amount of fuel delivered would decrease too. However, with NO2, you could maintain the fuel delivery at the rate you use at FTH, and provide enough NO2 to make up for the thinner air. So your engine is producing FTH power above FTH, and the existing fuel pump and cooling will probably suffice within reason. In addition, NO2 under pressure would initially have a cooling effect in the inlet manifold.

In contrast, water methanol works by cooling the charge and so preventing pre-detonation at higher manifold pressures than can normally be used. The higher manifold pressure is achieved by running the supercharger harder, thus cramming more air into the chamber, thus allowing more fuel to be burned and thus producing more power. The neat bit, and the bit where the water comes in, is that the water sprayed into the charge in the inlet manifold cools it and prevents it from pre-detonating (˜pinging' or ˜knocking' for the petrol heads). Because this system relies on the supercharger to produce extra manifold pressure, this system only produces extra power below FTH, although presumably it would produce extra cooling above FTH.

Looking at the elements of the system, it requires that the supercharger run at a higher speed in order produce the higher manifold pressure. It also requires that more fuel is delivered to take advantage of all that extra air shoved into the chamber. This means you would have to do something to your supercharger governor, and you'd probably need a new fuel pump (or perhaps changes to the settings of the existing one?).


So it seems to me that you would need to do some important modifications to your motor if you wanted to change from NO2 to water methanol, but less if you wanted to change the other way.


cheers,
Ratsack

DKoor
04-07-2008, 05:34 AM
I think that some of the changes could probably be introduced with some modifications to the existing airframe.

JG53Frankyboy
04-07-2008, 05:55 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ratsack:
.................................
However, if you only operate the system above full throttle height (FTH), then you probably don't need a new cooling system or fuel pump. Above FTH, the supercharger can no longer maintain maximum manifold pressure. This is the pressure at which the motor would normally be delivering and burning maximum fuel, and producing maximum heat. Above that height, the manifold pressure would normally decrease with altitude, and the amount of fuel delivered would decrease too. However, with NO2, you could maintain the fuel delivery at the rate you use at FTH, and provide enough NO2 to make up for the thinner air. So your engine is producing FTH power above FTH, and the existing fuel pump and cooling will probably suffice within reason. In addition, NO2 under pressure would initially have a cooling effect in the inlet manifold.

................ </div></BLOCKQUOTE>

the GM1 systems used NO2 ................

Ratsack
04-07-2008, 06:00 AM
Yes. I know the GM1 was NO2. Goering's Mixture.

I also understand that the mods might be done with existing airframes.

What I am trying to understand better is the breadth of the mods needed. It has been suggested in another thread that the conversion from GM1 to MW50 is as simple as changing the injectors. While this particular detail was not particularly critical to that thread, I find the matter interesting and so I've raised it in another thread of its own.

The thing that strikes me about MW50 is that it would require some modification to the operation of the supercharger to make it produce the extra manifold pressure. This would be in addition to any other changes, such as the change of injectors. I also wonder how they coped with the extra fuel demand.

cheers,
Ratsack

Kurfurst__
04-07-2008, 07:27 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ratsack:
In contrast, water methanol works by cooling the charge and so preventing pre-detonation at higher manifold pressures than can normally be used. The higher manifold pressure is achieved by running the supercharger harder, thus cramming more air into the chamber, thus allowing more fuel to be burned and thus producing more power. The neat bit, and the bit where the water comes in, is that the water sprayed into the charge in the inlet manifold cools it and prevents it from pre-detonating (˜pinging' or ˜knocking' for the petrol heads). Because this system relies on the supercharger to produce extra manifold pressure, this system only produces extra power below FTH, although presumably it would produce extra cooling above FTH. </div></BLOCKQUOTE>

Almost correct. One tidbit about water injection is that by cooling the charge, it provides a bit of a extra power even if you do not increase manifold pressure - ie. also above FTH while your MW system is running, where your your manifold pressure is actually decreasing with altitude due to the superchargers limitation. The methanol (wood alcohol), which`s primary function is being an anti-freeze additive to water, is a sort of fuel on its own right, it does act like very high octane fuel with high knocking properties, but IIRC it has somewhat less volumetric energy than fuel.

To cut the long story short, the figures show that appx. 4% higher power output (ie. ca 50-100PS) is obtained with methanol-water injection, even if the manifold pressure remains the same, ie. above FTH.

The DB 605G (= DB 605AM`s maiden name) curves, from 15 November 1943 show, for example

At Sea level:
at 1.7ata, 2800rpm, without MW50 injection : 1700 PS output
at 1.7ata, 2800rpm, _with_ MW50 injection : 1800 PS output


At 10km altitude (ie. well above FTH):
at 1.7ata, 2800rpm, without MW50 injection : 790 PS output
at 1.7ata, 2800rpm, _with_ MW50 injection : 850 PS output


<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
Looking at the elements of the system, it requires that the supercharger run at a higher speed in order produce the higher manifold pressure. It also requires that more fuel is delivered to take advantage of all that extra air shoved into the chamber. This means you would have to do something to your supercharger governor, and you'd probably need a new fuel pump (or perhaps changes to the settings of the existing one?).
So it seems to me that you would need to do some important modifications to your motor if you wanted to change from NO2 to water methanol, but less if you wanted to change the other way. </div></BLOCKQUOTE>

Superchargers actually deliver a lot more pressure than needed for the engine below FTH, there`s an existing reserve available in them.
On fixed supercharger gear systems (ie. Merlin, BMW, almost all inline engine of WW2), the supercharger runs at constant speed, creating a lot more pressure below their FTH; the amount of air the engine is actually getting is controlled by how much the throttle butterfly is opened. The downside is that below FTH by compressing the air you also heat it up, which in the end decreases output greatly. The see-saw power curves of the Merlins, BMWs etc. are a result of this.

On the DB series engines, the supercharger speed is not fixed, but variable. The actual supercharger ratio is changed accordingly to the supercharging needs of the engine (ie. the supercharger is being run faster and faster as altitude increases, and more hard work is required from it in order to deliver constant pressure from the rarified air. It runs at maximum speed at FTH. How fast the supercharger runs is governed by oil pressure supplied to a hydraulic clutch - at low altitude, the supercharger is run slow with a lot of slipping, with low oil pressure delivered to it.

There are two oil pumps responsible for the oil pressure (and thus the supercharger speed), one delivers constant pressure at all times, this is pretty much a fixed ratio MS gear, and its characteristics are well visibile on DB 605 power curves, ie. straightly increasing up to ca. 2000 m altitude, like on Merlins, BMWs etc. The second oil pump has variable delivery rate; the delivery of oil into the the flywheel is gover by a barometric unit. In practice it works as a variable ratio supercharger, the barometric unit controlling the amount of oil pumped into the flywheel, and thus the oil pressure in the flywheel, and thus the amount of slip in the hydraulic clutch, and thus in the end the supercharger`s running speed.

MW50 boosted curves of DB 605AM engines show the FTH in the first gear (fixed s/c ratio)are lower than on 605A engines, indicating that the first fixed oil pump work the same as before, and the second pump kicks in at much lower altitudes. Basically it shows that the it only requires to re-adjust the settings of the barometric unit so that it would deliver higher amounts of oil (=&gt; more oil pressure, less slip, higher supercharger speed) in the flywheel earlier.

The fuel pumps appear to be less of a problem. The Bf 109 had two fuel pumps to supply the engine with fuel, each with IIRC something like 470 liter/hour capacity. This corresponds to roughly about twice the capacity needed (redundancy..?), as the DB 605A (w/o MW50 operating at 1.42ata) consumes roughly about 470 liter/hour at full power. The DB 605AM, with MW 50 and at 1.7ata, does not require much more - its peak consumption at max power output is 560 liters/hour. Even the 605D, at 2000 PS, requires only 650 liter/h to be delivered, but thats a different engine, different components (oil pumps for example, were new and of higher capacity).

So what you need is to adjust the settings of the fuel pump delivery rate to higher rates, the butterly throttle (that it would open up more when MW50 enabled AND the throttle handle is pushed through the 100% rating region, which results in the butterly being opened to allow through 1.7ata pressure AND opens up the valves of the piping that leads from the rear container, which is under pressure. This basically starts MW50 injection into the eye of the supercharger.)

These are pretty basic flight mechanic routines - ie. to correctly set-up the engine`s valve timing, mixture control, supercharger speed etc. From the diagrams I have seen, the adjustment of the system can be performed via adjusting a couple of screws.

No41Sqn_Banks
04-07-2008, 08:37 AM
Scary stuff in this thread http://forums.ubi.com/images/smilies/25.gif

JG14_Josf
04-07-2008, 08:43 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">The neat bit, and the bit where the water comes in, is that the water sprayed into the charge in the inlet manifold cools it and prevents it from pre-detonating (˜pinging' or ˜knocking' for the petrol heads). </div></BLOCKQUOTE>

Ratsack,

If you don't mind I'd like to offer something on that quote above.

As far as I've learned there are two separate conditions identified in motor operation that are similar to human operating conditions of heat exhaustion and heat stroke.

The reason these two similar conditions are separated into two separate, but similar, conditions has to do with treatment. It may be very wrong to misdiagnose one condition or confuse one condition with the other condition.

You say this:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">So it seems to me that you would need to do some important modifications to your motor if you wanted to change from NO2 to water methanol, but less if you wanted to change the other way. </div></BLOCKQUOTE>

The differences between Heat Stroke, Pre-Ignition, Heat Exhaustion, and Detonation are similar to the quote above.

I can further confuse things or I can go back and research an old topic to make sure that I don't make any error in reporting. I can also speak freely from a place of admitted ignorance.

One ailment is not nearly as serious as the other ailment and both ailments may be caused by the same thing or combinations of causes may, at varying degrees, may cause a minor problem to become a very serious problem.

I think that detonation was the serious problem (as heat stroke is the serious human problem) compared to the less serious problem of pre-ignition (or heat exhaustion). One is life threatening and the other is farther from being life threatening.

The bottom line between the seriousness of one compared to the other is excessive pressure, at the wrong time in the cylinder, that leads to catastrophic damage such as a hole blown through the top of the piston. The other, less serious condition, may ˜knock' or ˜ping', I'm not sure, and cause damage over time.

I have to check now:

Pre-Ignition - Detonation (http://www.misterfixit.com/deton.htm)

That looks good enough.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Detonation (also called "spark knock") is an erratic form of combustion that can cause head gasket failure as well as other engine damage. Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. The hammer-like shock waves created by detonation subject the head gasket, piston, rings, spark plug and rod bearings to severe overloading.


Mild or occasional detonation can occur in almost any engine and usually causes no harm. But prolonged or heavy detonation can be very damaging. So if you hear knocking or pinging when accelerating or lugging your engine, you probably have a detonation problem.
</div></BLOCKQUOTE>

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Another condition that is sometimes confused with detonation is "preignition." This occurs when a point within the combustion chamber becomes so hot that it becomes a source of ignition and causes the fuel to ignite before the spark plug fires. This, in turn, may contribute to or cause a detonation problem.


Instead of the fuel igniting at the right instant to give the crankshaft a smooth kick in the right direction, the fuel ignites prematurely (early) causing a momentarily backlash as the piston tries to turn the crank in the wrong direction. This can be very damaging because of the stresses it creates. It can also localize heat to such an extent that it can partially melt or burn a hole through the top of a piston!

</div></BLOCKQUOTE>

WikipediA (http://en.wikipedia.org/wiki/Engine_knocking)

I think the Wikipedia article and the first article contradict each other. It seems to me that the important difference between detonation and pre-ignition is timing and therefore seriousness. I could be wrong too – of course.

If detonation, by definition, only occurs after the normal spark timing event the possible damage caused by detonation is limited to pressure (and heat) build up occurring after normal ignition timing.

If pre-ignition occurs the possibility of building pressure and heat even before the normal spark ignition timing event may increase the possibility of building more pressure, and more heat and therefore be more damaging.

One more source (http://www.streetrodstuff.com/Articles/Engine/Detonation/)

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Confusion and a lot of questions exist as to detonation and pre-ignition. Sometimes you hear mistaken terms like "pre-detonation". Detonation is one phenomenon that is abnormal combustion. Pre-ignition is another phenomenon that is abnormal combustion. The two, as we will talk about, are somewhat related but are two distinctly different phenomenon and can induce distinctly different failure modes. </div></BLOCKQUOTE>

That one looks promising.

I'm reading.

Thanks for the topic.

M_Gunz
04-07-2008, 09:13 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ratsack:
In contrast, water methanol works by cooling the charge </div></BLOCKQUOTE>

And cooler air is denser than non-cooled compressed air so you still get to pack in more O2
pressure. Consider though the cooling effect from pressure-dropped nitrous as opposed to
merely cold water-methanol, even there the nitrous has far more effect per volume used.

EDIT: It's the expansion from heat that's limiting the compression, cooling that makes higher
compression/more oxygen possible.

JG14_Josf
04-07-2008, 11:14 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">There are two oil pumps responsible for the oil pressure (and thus the supercharger speed), one delivers constant pressure at all times, this is pretty much a fixed ratio MS gear, and its characteristics are well visibile on DB 605 power curves, ie. straightly increasing up to ca. 2000 m altitude, like on Merlins, BMWs etc. The second oil pump has variable delivery rate; the delivery of oil into the the flywheel is gover by a barometric unit. In practice it works as a variable ratio supercharger, the barometric unit controlling the amount of oil pumped into the flywheel, and thus the oil pressure in the flywheel, and thus the amount of slip in the hydraulic clutch, and thus in the end the supercharger`s running speed. </div></BLOCKQUOTE>

Kurfurst,

That is an interesting description. Like this one:

Here (http://www.aviation-history.com/engines/db605.htm)

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Centrifugal supercharger on port side of engine driven through a fluid coupling by a shaft at right angles to crankshaft. This shaft is driven through bevel gears from the crankshaft, variation in propeller speed secured through variable filling of fluid coupling by two-stage engine driven pump receiving lubricating oil from the main pressure filter. </div></BLOCKQUOTE>

A hydraulic/mechanical diagram would be neat to see.

http://www.aviation-history.com/engines/db601na.jpg

That does show the direct connection between engine crank shaft and the shaft that drives the supercharger impeller.

If the engine crank shaft turns the compressor (supercharger) driven shaft (impeller) will turn at a ratio determined by gear ratio. That part is a fixed ratio.

The 109 engine turns a low rpm and the supercharger driven shaft (impeller) turns at low rpm.

The 109 engine turns a full rpm (it runs at full rpm at full throttle because it has a constant speed prop) therefore the supercharger driven shaft turns at full rpm.

Between the impeller and the compressor is a fluid coupling (not actually a clutch if by ˜clutch' the term intends to suggest spring loaded friction plates loaded against a steel plate) where impeller rpm is not necessarily going to be compressor rpm.

The supercharger driven shaft is separated from the supercharger compressor. Oil flow links the impeller to the compressor.

The 109 fluid coupling (torque converter), if I am not mistaken (and it sure would be nice to have more data), is much like an automatic transmission fluid coupling in modern automobiles, where the engine drives an impeller. The impeller is an oil pump. Another oil pump supplies the impeller with oil from a tank. If the impeller is turning at full rpm because the engine is at full rpm the amount of oil that can be pumped by the impeller is much or even very much oil. Lots of oil can be moved from wherever the oil is to where the oil will be as that impeller turns at full rpm. The impeller part will turn at full rpm if the engine is turning at full rpm.

Auto Trans (BMW) (http://www.e38.org/transfund1.pdf)

That link describes a torque converter or fluid coupling.

The impeller moves oil so as to move the compressor (supercharger). The oil moves the compressor. The compressor moves the air.

The engine moves the gears. The gears move the impeller. The impeller moves the oil. The oil moves the compressor. The compressor moves the air that runs the engine (oxidizes?).

I think it is important to understand this fluid coupling or torque converter first before figuring out how compressor rpm is governed and therefore how boost pressure is governed.

Is rpm governed by reducing and increasing oil volume/pressure? If so it would be nice to see a diagram showing exactly how that was done.

Kurfurst__
04-07-2008, 11:26 AM
This is pretty much how the stuff works, its basically a hydraulic clutch - like in cars with automatic transmision - set by a barometer..

http://i38.photobucket.com/albums/e133/Kurfurst/DB601and5_superchargeroperation.png

http://i38.photobucket.com/albums/e133/Kurfurst/DB601and5_superchargeroperation_sch.png

Result : note the smoothness of the power curve, no zig-zag :

http://i38.photobucket.com/albums/e133/Kurfurst/DB605Agraph.jpg

TX-Gunslinger
04-07-2008, 11:38 AM
One would think that the Jumo-213E-1 would be the optimal exemplar to study the two systems with.

S~

Gunny

Xiolablu3
04-07-2008, 01:06 PM
Guys, I dont know too much about htis stuff, but why did the Allies not use MW50?

Was it not compatible with the Merlin for some reason?

If the Merlin powered fighters were around the same power as the DB engines without MW50 benefit (P51/Spitfire), then surely they would be even more powerful with a similar MW50 system.
Did MW50 reduce engine life by a large amount?

Can someone explain to a simpleton like me just why it wasnt used?

Kurfurst__
04-07-2008, 01:35 PM
They did, they just didnt call it MW 50, but ADI (Anti Detonant Injection), Water Injection. The P-47D, F4U, Hellcat, P51H had it, and perhaps some more.

Its the same thing, a mixture of water and some sort of alcohol as anti-freeze (its cold up there!). MW50 itself simply stands for Methanol-Wasser 50, ie. 50 parts water, 50 parts methanol (or ethanol could be substituted, its called EW-50, the ration could be 70-30 - EW30, MW30 -, or even just pure water!).
In addition there was 1% lubricating oil, so the recipe is actually 49,5% water, 49,5% methanol/ethanol, 1 % Schutzöl 39.

One particular reason as to why the Merlin engined fighters didnt use ADI earlier could be that the two staged Merlins were built with an intercooler, that does more or less the same stuff, charge cooling. MW50/ADI though adds internal cooling to the cylinders (which is the purpose it was used for on the P-47 I believe.)

JG14_Josf
04-07-2008, 02:08 PM
Kurfurst,

Thanks, that is more data.

Full speed (speed of the compressor) occurs when full oil flow is directed to the coupling (interior) and it looks like that cuts off oil spray to the coupling exterior. Less oil going to the exterior means more oil going to the interior of the fluid coupling.

Slip is not defined exactly. I wonder what the fluid coupling looks like and if it resembles the automobile torque converter. Will the impeller spin freely without any oil flow internally (assuming the impeller was not hooked up to the engine such as one would find at the shop before installing a new unit onto an engine) and the compressor spins freely.

Having one on the bench: could the air side (compressor spin by hand) one way and the impeller be spun the other way such as a mechanic might do to make sure both sides spun freely (without oil).

So...without any oil flowing from the Slip Control valve to the coupling interior the engine could turn the impeller without having any force directed at turning the compressor. As soon as oil begins to flow from the slip control to the coupling interior the impeller forces oil flow to the compressor side of the fluid coupling and therefore the compressor begins to turn.

Without a lot of oil flowing through the fluid coupling (and therefore a lot of slip is occurring and the compressor is not turning fast) the ability to carry out heat with the oil (and the ability to generate heat because one side is spinning fast and the other side is not spinning fast?) inspired the redirection of governed oil (the flow of oil taken from the coupling interior) to the coupling exterior.

The atmospheric bellows looking thing expands as atmospheric pressure decreases (as the plane goes higher) since the inside of the bellows must be a sealed volume of gas or air and that expansion moves the lever that moves the spool valve to increase and decrease the rate of oil volume sent to the coupling interior or exterior (more oil volume to the exterior is less volume to the interior).

There is another adjustment where more or less oil flow is sent to the sump or scavenge line/port and that appears to be a low speed (high slip) setting since it looks like it gets cut off as the spool valve moves to the higher speed (going left to right in the diagram) before the coupling exterior port is cut off by the spool (and thereby redirecting all the oil to the coupling interior).

Thanks and please consider posting more data on that fluid coupling if you have any.

Ratsack
04-08-2008, 10:25 PM
Thank you for the information, Kurfurst.

cheers,
Ratsack