Time limit for MW50 usage > 109

[Wotan]

Its not an either or question.

GM-1 was to provide more power at higher altitudes (above 7000m or so).

It wasn't widely used in service. Although some 109 variants (109E-7z etc...) were designed with GM-1 in mind.

MW-50 was simply injecting water into the eye of the SC to cool the charge. The cooler the charge the less risk there is of detonation and thus the engine can be run at higher boost below FTH. Above that (5,500m or so for most LW planes) MW-50 isn't needed because the SC is already losing power.

MW-50 and GM-1 are completely different not only in 'what they are' but what they were 'used for'. A comparison question of 'which is better' makes no sense.

With the introduction of the AS engines and DB 605D (which meant a larger supercharger) providing better performance and extending FTH GM-1 wasn't need for the late war 109s.

GM-1 = high alt performance

MW-50 = higher boost below FTH.

For example the Ta-152H had both MW-50 and GM-1.

[agent 009]

The reason I asked an either or question was because GM1 appeared earlier, then MW 50 seemed to replace it as it appeared after.

Thanks for explanation though. Both do provide extra power, so they are similiar engine adds.

[Meyer]

They're not similar.... GM1 provided oxygen at altitudes where supercharger couldn't (above FTH) , and MW50 was a antidetonant/refrigerant so you could raise the manifold pressure using the supercharger (below FTH)

[Angus]

So, one for high-up, and one for low-down?
Clever.
But some weight penalty?

[agent 009]

They were similiar in that they provided extra power. Yes they did it at different altitudes, understood, but still extra power is extra power.

[Kurfürst]

The power boost GM-1 prodived was scary : + 300 HP at above 1500m of the full throttle height...

Ie. the standard DB 605A-1 had 750-790 PS output at 10000m. GM-1 would boost it to 1000-1100 PS at 10 000meter altitude... and the speed is boosted by 120 kph... to well over 700...

[Wotan]

They were similiar in that they provided extra power.

MW-50 didn't provide 'extra power' it simply cooled the charge. Any extra power was the result of being able to run at higher boost with out the fuel detonating pre-maturely.

GM-1:

I will quote Hohun from a previous post:

GM-1 was the German WW2 code-name for N2O (nitrous oxide, or laughing gas).

N2O can be added to the fuel-air mixture of an internal combustion engine. In the compression cycle, it's broken up into its components, releasing oxygen that can be used for combustion.

As the challenge of high-altitude flight mainly consists of getting enough oxygen into the cylinder to maintain adequate power - which due to the decreasing air density becomes more and more difficult at altitude - N2O equates to extra power.

In fact, N2O was injected into the supercharger in liquid form through small jets, and each jet gave a constant power boost when employed. Depending on the type, you might have a 120 HP jet and a 240 HP jet, which of course added 360 HP when used in combination.

That's the resason N2O was available in steps - you couldn't add 360 HP to an engine that was already running at close to full power, or the resulting forces would destroy vital parts of the engine.

This is the main reason N2O was preferred over pure oxygen, which could be (and experimentall, was) used for the same purpose - it just gave too much power.

The nitrogen share of the nitrous oxide has a benefit, too, since it absorbs some energy on being broken up in the cylinder, controlling the detonation and allowing higher pressure.

Since N2O is injected into the supercharger as a liquid, it also gives a charge cooling effect on evaporation (cooler air means more oxygen in the same volume).

Initially, N2O was stored under high pressure to keep it liquid (laughing gas, after all, is a gas under standard conditions), but that meant the N2O vessels blew up like a bomb on being hit, so from 1941/42 on it was stored at very low temperature in an insulated tank that kept the content at less than -90 °C for as long as the sortie lasted.

(It was used by bombers like the Ju 88 and by reconnaissance planes like the Ju 86 as well, so that could be quite a long time. For fighters at readiness on the ground in the hot summer sun, though, the insulation would not have sufficed and the N2O would have begun to boil out through the safety valve after a while.)

For comparison: 0.1 kg/s of N2O injection gave extra 300 - 400 HP, virtually out of nothing.

The only drawbacks were the weight of the system (which also included compressed air bottles to force the N2O out of the insulated tank), and - more importantly - the high rate of consumption. If 0.1 kg/s gave 350 HP, that made for a specific fuel consumption of 1000 g/HPh, which compares very unfavourably to the DB601A's normal 220 g/HPh at high power :-)

So, N2O was bad for range, but great for high-altitude power.

Oh, by the way, someone mentioned that N2O was to be used for short bursts only. According to what I have read, it could be used as long as it was available and in fact short bursts were to be avoided as filling and emptying the N2O lines took some time and created some engine management difficulties.

Regards,

Henning (HoHun)

[agent 009]

So the plane went "faster" when MW 50 was applied, hence more power.

[Wotan]

That's not how it works.

With the GM-1 N2O released O2 and the O2 was 'burnt'. This additional oxygen at high altitude allowed for more power.

MW-50 was a 50/50 water-methanol mix that didn't burn it just cooled the charge. You get more power because you run the engine at a higher ATA. (move the throttle all the way up).

MW-50 was 'turned-on' by a switch on the dash. It was then injected only when the throttle was pushed up all the way to stop. Pull back the throttle injection stopped.

You can't compare the two as if one would be better then the other, they were used for different things, operated differently etc...

You may keep this circular line of discussion going if you like but your question was answered.

Your original question was:

Mw 50 better than GM 1?

With your on-going words games you look like some one who is trying to avoid being wrong.

[Angus]

So, one is the nuke, and the other one keeps it from cooking the engine?

[Orka]

Meyer dixit, thats how it works. :

GM1 provided oxygen at altitudes where supercharger couldn't (above FTH) , and MW50 was a antidetonant/refrigerant so you could raise the manifold pressure using the supercharger (below FTH)

GM1 not mean rise engine power, that engine only can run at max MP,  just raise FTH. So you have an engine runnig at max power@higher alt.
MW50 provide cooling effect, just rise MP. So you have an engine running above max power w/o cooking.


@Wotan

Im still alive, i think S!


regards

[agent 009]

No word games really. I was attempting to find out which of these 2 devices was better, hence more efficient, less problematic, easier to work on, weighed the least, & last but not least - which one did the job of making the plane go faster "better".

& I'm not wrong when I say both of these devices did the same job, ( albeit at different altitudes ), which is- make the plane go faster. Now if a plane goes faster, technically speaking more power has been obtained.

Different methods are employed by these devices to achieve this goal which is very interesting & I appreciate explanations. But the Germans, ( on single engined fighters ), used GM1 early, then seemed to favor MW 50 boost, (152 being an exception employing both), which may well be a hint that mw 50 was prefferred, my speculation. & that's why I asked.

[butch2k]

Using GM-1 was an hassle, the product being highly volatile you could not fill the tank and just wait a few days before using it.
Moreover it lost most of it's interest when the engine being produced reached FTH in the 7-8km range, indeed GM-1 could not really be used below FTH+1500/2000m meaning that you had to fly at 9000-10000m to use it.
At such an altitude you most likely need a pressurised cockpit and it's very unlikely you'll encounter anyone except for some recce a/c.
G-5/U2 and G-5/U2/AS were kept with GM-1 just for such business, intercepting high flying mossies and the likes.

Most usefull was the MW-50 boost which permitted higher outputs for a long time at usual combat altitude.

[agent 009]

Thankyou Butch.