correct as-is MW50 - different (new) behaviour

[scoobie]

Hi, I might have broken down my Bf 109 or the newest update introduced some changes.

 

IIRC, previously in 109 you could enable/disable MW50 with the switch and when it was OFF and you moved throttle full forward, ata was... can't remember, 1.5 or something. If you then switched MW50 on, you could hear that sudden roar and ata jumped to 1.8 or so.

Simply put, there was obvious, clear difference between MW50 working and not working.

 

As of today, my Bf 109 works differently, like this:
1. MW50 switch OFF + move throttle slightly forward from nearly full forward to exactly full forward:
The roar kicks in (why?), ata abruptly jumps from 1.45 to 1.8 (why?). MW50 pressure gauge shows 0.
2. MW50 switch ON + move throttle as above:
The roar kicks in, ata abruptly jumps from 1.45 to 1.8. MW50 pressure jumps to 0.6 kg/cm^2.

 

Point 2 above works as previously. Point 1 - does not, is now different.

 

I have noticed only one difference - if you keep throttle full forward and turn MW50 on/off/on/off/etc. - there is slight slight difference in sound and Kommandogerat changes prop pitch (makes it coarser). Probably it changes pitch not to overrev the engine because of the increased boost, but there is no increased boost - ata is identical in both cases (close to 1.8).

 

Do you have an idea what might be going on here?

 

[LeCuvier]

My stable version was still at 2.71.7139, and it behaved exactly as the current OB 2.7.3. So the behaviour in scenario 1. is not new.

I'm not sure that the engine's behaviour in scenario 1. is wrong. The boost pressure does rise to 1.8,  but:

- I do not get any significant increase in indicated air speed; thus no gain in engine power.

- the engine apparently runs very roughly, because the entire cockpit shakes.

- the oil temperature increases.

- the engine finally overheats and breaks down.

In other words, you gain no power and if you persist in this mode you kill the engine.

The only thing that seems odd to me is that the engine sound does not change between the two modes. I'm no engine expert but I would imagine that the engine would produce a rougher sound in mode 1.

[scoobie]

As far as the version is concerned, I may be well wrong. Recently I've been flying the English beauty and the Jug, so the 109 was gathering dust for quite a while. It might have been some previous update where this change was introduced, I can't be sure, I admit.

 

1 hour ago, LeCuvier said:

because the entire cockpit shakes (...)

the engine sound does not change between the two modes

Confirm! Both things. As for the other phenomena you mentioned - I wasn't careful enough to notice. I'll give it a go again.

 

EDIT: Couldn't check the airspeed, because... I killed the engine sooner. Twice

Just to make sure - the "scenario 1" is MW50 off (at least for me), where strange things happen. I have no complaints about "scenario 2" with MW50 on - it seems to work as it always used to. MW50 OFF is where things are now different. (I hope we're talking the same thing.)

 

I know 109 was "revisited" some time ago - for example the pump control lever was changed to axis and bodged in the process (@pmiceli provided a workaround in another thread), maybe there have been some more "collateral damage" to the module? I don't know, but it's definitely DIFFERENT, so if there was no plan to update/upgrade 109, apparently it is some unintended change. Just my $0.02 of guesswork.

Edited July 10, 2021 by scoobie

[LeCuvier]

1 hour ago, scoobie said:

...Just to make sure - the "scenario 1" is MW50 off (at least for me), where strange things happen.

Yes. Scenario 1 = MW50 OFF

[grafspee]

Since i own K-4 throttle and mw50 behavior hasn't changed.

If Mw-50 is off throttle behavior does not change.

Mw-50 switch only arm mw 50 injection.

Mw50 injection is started when throttle pass certain point

What you described is How Dora Mw-50 works.

In K-4 when you injecting Mw-50 you get increase rpm from 2600 to 2800 rpm 

If you run K-4 at 1.8ATA w/o MW-50 engine experiencing detonations this rapidly increasing temperature, it can damage pistons and it will kill engine in short time.

Above 28k ft you can use full throttle range w/o 50

You can see this WEP stop if you bring up control indicator

Edited July 10, 2021 by grafspee

[DB 605]

Yes, as others are confirmed, it's "always" been like that and work like it should. MW-50 injection will not change sound or anything itself; it just allows more boost and revs to engine without risk to detonation etc.  The "roar" you hear is simply because increased boost and revs.

 

Whether or not you should hear detonation/knocking sound when using 1.80 boost/2800rpm without MW-50, i don't know. Knocking sound is not always audible outside of engine.

 

In real life, if MW-50 was not available, throttle movement was limited to allow only 1.45 boost level.

[grafspee]

I heard the opinion that knock not always can be hearable due to wind or engine exhaust sound. I have heard knock in automobil engines, and if i took mufflers off i would not be able to hear after that. 

So when operating w/o mw 50 stop gate was installed on throttle. so rpm above 2600 was not available am i right or rpm governor was adjusted to allow 2800rpm ?

Being limited to 2600 bring large drawback at high alt. In DCS you can advance throttle to max at alt above 30k it gives quite a boost increase.

Edited July 11, 2021 by grafspee

[DB 605]

13 minutes ago, grafspee said:

 

So when operating w/o mw 50 stop gate was installed on throttle. so rpm above 2600 was not available am i right or rpm governor was adjusted to allow 2800rpm ?

Being limited to 2600 bring large drawback at high alt. In DCS you can advance throttle to max at alt above 30k it gives quite a boost increase.

 

I'm pretty sure it was still possible to use 2800rpm by adjusting propeller pitch manually, since books noted that only throttle lever movement was Limited.

[grafspee]

16 minutes ago, DB 605 said:

I'm pretty sure it was still possible to use 2800rpm by adjusting propeller pitch manually, since books noted that only throttle lever movement was Limited.

oh ok

[scoobie]

Unbelievable! How can anybody forget the module after a few months of not flying it!? Well, I can
Anyway, sorry for the drama and thanks for additional insight!

[itsukarine]

Sorry for reviving this, but there is definitely different behavior than the plane used to handle years ago. I'm not sure if it's entirely relevant to this specific post; didn't want to make a new one since I've not tested in bug-reporting conditions, but I've flown this thing extensively since like 2015 and the entire dash violently shakes with MW50 on or off and dies well before the "30 minutes of runtime" mentioned, pretty much identical behavior to:

On 7/10/2021 at 10:36 AM, LeCuvier said:

My stable version was still at 2.71.7139, and it behaved exactly as the current OB 2.7.3. So the behaviour in scenario 1. is not new.

I'm not sure that the engine's behaviour in scenario 1. is wrong. The boost pressure does rise to 1.8,  but:

- I do not get any significant increase in indicated air speed; thus no gain in engine power.

- the engine apparently runs very roughly, because the entire cockpit shakes.

- the oil temperature increases.

- the engine finally overheats and breaks down.

In other words, you gain no power and if you persist in this mode you kill the engine.

The only thing that seems odd to me is that the engine sound does not change between the two modes. I'm no engine expert but I would imagine that the engine would produce a rougher sound in mode 1.

In the past the performance would visibly improve in that I could get a lot more speed out of it without ever worrying about the temps, and the dashboard wasn't vibrating like it's attached to someone diagnosed with Parkinsons. It used to visually perform as if it were at 1.4ata just with the increased engine RPM sound. Is it possible that servers I'm playing have MW50 disabled?

[itsukarine]

20 minutes ago, itsukarine said:

Sorry for reviving this, but there is definitely different behavior than the plane used to handle years ago. I'm not sure if it's entirely relevant to this specific post; didn't want to make a new one since I've not tested in bug-reporting conditions, but I've flown this thing extensively since like 2015 and the entire dash violently shakes with MW50 on or off and dies well before the "30 minutes of runtime" mentioned, pretty much identical behavior to:

In the past the performance would visibly improve in that I could get a lot more speed out of it without ever worrying about the temps, and the dashboard wasn't vibrating like it's attached to someone diagnosed with Parkinsons. It used to visually perform as if it were at 1.4ata just with the increased engine RPM sound. Is it possible that servers I'm playing have MW50 disabled?

>Is it possible that servers I'm playing have MW50 disabled?
Huh, well, I found out that's actually probably what's happening by crawling through 605's post history since I couldn't find anything in search. (His name implied he's someone who would know these things lol)
Nevermind, I'll make another post if I hop into SP and see the same behavior, otherwise good to go.

Edited September 13, 2022 by itsukarine
typo

[grafspee]

Always check mw50 pressure gauge, if indicates 0 when engaged = no mw50 on board.

[NineLine]

So still correct as is

I will close this one, if you have issues please make a new post and include tracks and info. Thanks.