Question regarding the correct use of MW-50 and engine combat performance

[atsmith6]

Am I right to understand that:

 

In climb and a dogfight the correct maximum RPM setting is 3000 RPM, and in the dogfight I would inject MW-50 into the fuel for extra HP, or am I supposed to boost to 3250 RPM for short durations for maximum energy in a dogfight? I'm certain I can figure out what the sim will tolerate but I'd like to know what the prescribed method was in the real world.

 

As a side question: The 2700 RPM cruise setting in the Jumo 213 manual, is this maximum safe cruise RPM, maximum endurance (i.e. time in flight) or maximum range RPM?

 

And one more bonus: Does anyone know a good speed for maximum sustained rate of turn at 3000 RPM and or 3250?

 

Many thanks in advance!

Edited September 3, 2014 by atsmith6

[Dirty Rotten Flieger]

Well as I understand it the MW50 gives a cooling effect and a increased horsepower effect below full throttle height. Above full throttle height MW50 gives only cooling effect.

 

I don't know if the engine was supposed to be run at 3000 or 3250rpm but I imagine if it was me in the cockpit I would probably run at 3000rpm unless I had a good reason to push the engine harder... Like a mustang on my tail. Better to break the engine than get shot down knowing I could have pushed it harder.

 

I have read that the fw190D had a best turn speed of 400km/h which is a lot higher than most ww2 planes at about 300km/h.

 

Of course I could be wrong about everything...

[draken152]

In reality you can use MW50 only at full throttle. There was hidden switch what allows start only at full throtle... You can see it in scheme from Ersatzteilliste (number 7)....Also this is mentioned in operational instruction for MW 50 in FW 190 Lehrmittel....

[Derbysieger]

In reality you can use MW50 only at full throttle. There was hidden switch what allows start only at full throtle... You can see it in scheme from Ersatzteilliste (number 7)....Also this is mentioned in operational instruction for MW 50 in FW 190 Lehrmittel....

 

That's how it works in DCS as well. If you're not at max throttle pressing the MW 50 button does nothing but once you advance the Bediengerät full forward you can see the MW 50 gauge moving and you immediately need to correct the additional torque that is quite noticeable.

[Flying-Kane]

With MW50 switch off:

(max power output: 1750PS)

 

3000rpm = Kampf- und Steigleistung. (combat and climbing power)

3250rpm = Start- und Notleistung. (start and emergency power)

 

You can use "Steigleistung" as long as you want. Notleistung was limited to 30 min, if i remember correctly.

 

With MW50 switch on:

(max power output: 2100PS)

 

3250rpm + MW50 = Sondernotleistung. Something like "special emergency power".

 

That was limited to 10 minutes, afterwards you had to cool down the engine by lower rpm for at least 5 minutes.

 

Over 5500 meters, you have to turn off MW50, because the critical height of the Jumo is reached. That means, MW50 has little to no effect.

 

Historically, not all Dora's had the MW50 boost system. The auxiliary tank could be filled with extra B4 too. So it was not always available.

 

Hope it helps.

Edited September 4, 2014 by Flying-Kane

[BitMaster]

MW50 is a 50/50 mix of water and methanol.

 

The water functions as a coolant only by carrying away the heat from the piston and cylinder while it vapors during compression cycles.

 

The methanol mostly used as Anti-Freeze agent mixed in to avoid freezing, to which extend it adds to the extra power generated, I dunno, but recall an interview

with a german ace and he said it was only used to cool down the engine and methanol to avoid freezing of the water in the reservoir tank..

 

The actual performance gain is achieved by more Manifold Pressure that would otherwise generate excessive heat that could not be carried away without the water vapor.

 

It works best with high RPM and high MP....and good spark plugs !

 

Nitromethane is used the same way though it also adds a little bit of power itself unless overdosed and smoothens the engine's firing and allows lower idle. Nitromethane is added to the fuel permanently, not injected. Afaik it has not been used in WWII but it mainly functions as an internal COOLANT and not as a Power Additive as most people think.

 

Bit

Edited September 6, 2014 by BitMaster

[BitMaster]

Actually, the MW50 makes the engine less effective because the stichometric mixture now also contains incombustible water molecules that hinder a good homogenous firing in the cylinder.

 

Hence you need rather good spark plugs and more voltage so your spark reaches deep into the mixture...more Volts help best ( more RPM = more Volts with those old engines afaik ).

 

It's a kick in the teeth to pull you up even higher by the hair !

 

 

One could argue, there is LOTS of water involved anyway, why add more !

 

Yes, it is, but only after the ignition took place and H2O formed....

[Nedum]

Actually, the MW50 makes the engine less effective because the stichometric mixture now also contains incombustible water molecules that hinder a good homogenous firing in the cylinder.

 

Hence you need rather good spark plugs and more voltage so your spark reaches deep into the mixture...more Volts help best ( more RPM = more Volts with those old engines afaik ).

 

It's a kick in the teeth to pull you up even higher by the hair !

 

 

One could argue, there is LOTS of water involved anyway, why add more !

 

Yes, it is, but only after the ignition took place and H2O formed....

 

What? :megalol:

The "spray" transports extrem more oxygen and what is one thing we need for a good combustion?

 

Your posting was sarcasm?

Edited September 6, 2014 by Nedum

[sobek]

Actually, the MW50 makes the engine less effective because the stichometric mixture now also contains incombustible water molecules that hinder a good homogenous firing in the cylinder.

 

Incombustibility is not an argument. Nitrogen isn't combustible at temperatures reached by a healthy engine. I'd argue that because the water takes up evaporation heat out of the exhaust gas and turns it into additional pressure, it could even make the thermal performance better, but one would have to do the math to be sure.

[BitMaster]

What? :megalol:

The "spray" transports extrem more oxygen and what is one thing we need for a good combustion?

 

Your posting was sarcasm?

 

No sarcasm, just simple chemistry and some physics.

 

 

- You need a good performing spark plug because the mixture contains water vapor, just as if you ride/drive a car with open air inlet ala Kuryakyn.

Every Harley driver with open inlets will tell you that 45.000 Volts per plug ( single fire )are way better than 20.000 Volts for both plugs ( standard double fire, only 1 coil) when driving in rain and liters of water are sucked into your V2 per minute.

 

The oxygen your refer to is not atomic, it is tight into a H2O molecule that won't break apart just by this little compression alone. Electrolysis needs Ampere and Volts, not pressure.

 

Even more H2O forms from H and O atoms that originate from the benzol

molecule... very basic organic chemistry. That H20 molecule is as hot as the combustion taking place inside the combustion chamber, thus does not do any cooling or any other good dead.

 

Check the YT videos, I dunno which one it was cause I watch alot of them but the Ace clearly said, MW50 basically just cools your engine so you can give more MP.

 

Bit

[BitMaster]

Incombustibility is not an argument. Nitrogen isn't combustible at temperatures reached by a healthy engine. I'd argue that because the water takes up evaporation heat out of the exhaust gas and turns it into additional pressure, it could even make the thermal performance better, but one would have to do the math to be sure.

 

 

Yes, for simplicity I excluded backpressure and methanol.

 

The real deal comes from the water taking away the heat from hot surfaces by evaporation. Everything else is a by product/effect I guess, to the good or bad.

 

Bit

[BitMaster]

....... Nitrogen isn't combustible at temperatures reached by a healthy engine...........

 

 

Nitromethane is not atomic N and indeed does combust BUT it carries less energy than Benzol ( energy released through braking up molecular bindings ).

 

That means, if you add only a little Nitro into your engine it will help it to fire better and smoother with only a little to no performance loss. This goes for like 1-10% Nitromethane, if you add more, like up to 30 or even 40 % you only cool down the engine ( desert climate etc. ) but for the loss of power as nitromethane, as said, releases less energy when broken apart by a redox reaction.

 

Bit

[sobek]

Nitromethane is not atomic N and indeed does combust BUT it carries less energy than Benzol ( energy released through braking up molecular bindings ).

 

I wrote Nitrogen, not Nitromethane, to illustrate that incombustible substances in the mixture are not necessarily a problem (aside from displacing oxygen). You wrote that the problem is the incombustibility of water, which is not correct. A reduced reaction rate is a different matter altogether, although i'm not certain the water really does cause this.

 

Edit: Btw. athmospheric nitrogen isn't atomic, atomic nitrogen is indeed rather reactive and will bond to oxygen easily, resulting in nitric oxide. Athmospheric nitrogen consists of diatomic molecules.

Edited September 6, 2014 by sobek

[fjacobsen]

Also noet that air containing more moisture will expand more than dry air.

 

I think most people have found that their cars perform better in moisterous/foggy weather than in dry air at the same temperature.

 

FinnJ

[KLR Rico]

^ I don't think so...

 

Humid air is less dense than dry air, and everything else being equal, an engine will have worse performance.

[BitMaster]

I do know that when I used to kick the V2 alive at night, after a heavy rain, it would roar twice as loud and run like hell. But this is with Carb, Hypercharger & Single Fire Coils ( 3x the voltage on plugs ).

 

With an "i" injection engine with airflow meter you won't feel anything I guess, but I have a VW Golf Diesel that is not that much effected by this effect as naturally aspirating engines.

 

 

I tried to find that Fw YT vid but had no luck.... I keep on searching

 

 

Bit

[BitMaster]

I wrote Nitrogen, not Nitromethane, to illustrate that incombustible substances in the mixture are not necessarily a problem (aside from displacing oxygen). You wrote that the problem is the incombustibility of water, which is not correct. A reduced reaction rate is a different matter altogether, although i'm not certain the water really does cause this.

 

Edit: Btw. athmospheric nitrogen isn't atomic, atomic nitrogen is indeed rather reactive and will bond to oxygen easily, resulting in nitric oxide. Athmospheric nitrogen consists of diatomic molecules.

 

 

I seem to have misunderstood your Nitrogene/Nitromethane quote.

 

Sure, N is present as N2 in ambient air and we can be happy it reacts not as happily as you described but needs lots of enthalpy energy to get kicked into reaction, otherwise all our O2 would be gone in a split second... there is roughly 4 x times the N around us than O oohhhhh oh :)

 

Some fire extinguishers use N2

 

In german, the casual name for N is "Stick-Stoff" ( like T-stoff and Z-Stoff for the He-Salamander etc.. )

Stick = abbreviation for suffocate = if you only inhale N you will suffocate.

 

What really boosts is NO2 injection......oooomps :)

 

 

Bit

[sobek]

What really boosts is NO2 injection......oooomps :)

 

NO2 is nitrogen dioxide. Lachgas is N2O. ;)