Merlin negative G cutout too quick?

[[RS]Boomer]

Originally Posted by klem

I am finding that the Merlin engine misfires at the slightest nudge down of the nose, nothing like a nose pushover. This also happens in level flight with some slight movement say due to turbulence or a mere touch of the stick however much I adjust the Mixture.

Can this be correct? We all know the story of negative G and the later Tilly Orifice but would our Fighter Aircraft engines ever have been so susceptible to Negative G that it is impossible to fly them straight and level without them constantly misfiring/puffing black smoke?

I agree, it is way too touchy.

[JG1_Luckystrike]

too much

[Viper2000]

Originally Posted by klem

I am finding that the Merlin engine misfires at the slightest nudge down of the nose, nothing like a nose pushover. This also happens in level flight with some slight movement say due to turbulence or a mere touch of the stick however much I adjust the Mixture.

Can this be correct? We all know the story of negative G and the later Tilly Orifice but would our Fighter Aircraft engines ever have been so susceptible to Negative G that it is impossible to fly them straight and level without them constantly misfiring/puffing black smoke?

http://www.youtube.com/watch?v=9BCl8...eature=related

25 seconds in you can see and hear the real behaviour. It's obviously difficult to estimate what the g loads were during the roll, but it looks more like reduced positive than actual negative g to me...

An excellent description of the problem is found on page 5 of this accident report:

http://www.aaib.gov.uk/cms_resources...pdf_501355.pdf

It is important to recognise that the negative g cut is a two stage phenomenon of lean cut possibly followed by rich cut, with the large amount of black smoke in the exhaust being symptomatic of over-fuelling (whether the engine actually cuts out or not is a function of the degree of over fuelling).

You can see this in the video; the smoke starts some time after the aeroplane passes 180º roll angle.

[Space Communist]

Originally Posted by Viper2000

25 seconds in you can see and hear the real behaviour. It's obviously difficult to estimate what the g loads were during the roll, but it looks more like reduced positive than actual negative g to me...

An excellent description of the problem is found on page 5 of this accident report:

http://www.aaib.gov.uk/cms_resources...pdf_501355.pdf

It is important to recognise that the negative g cut is a two stage phenomenon of lean cut possibly followed by rich cut, with the large amount of black smoke in the exhaust being symptomatic of over-fuelling (whether the engine actually cuts out or not is a function of the degree of over fuelling).

You can see this in the video; the smoke starts some time after the aeroplane passes 180º roll angle.

Yup I think that cinches it. I had forgotten that little tidbit form the movie. You can clearly see it just takes a second for it to be a problem.

[IvanK]

This has been brought up directly with the Devs. I agree its way to sensitive at the moment.

[Blackdog_kt]

Well, it seems more forgiving than IL2 to me, at least the engine doesn't completely turn off. Plus, the video shows it doesn't really take long to cause trouble and is consistent with a veteran's accounts in BBC's "battle of britain: the true story".

The way he describes it is just the way it appears on the BoB film intro posted above, which clearly indicates fuel starvation followed by an over-rich condition:

stage 1: lack of positive G forces the carb floater to the top of the fuel sump along with any fuel in it(is sump the correct word? let's say "feeding reservoir between fuel tank and engine" if it's not), causing fuel starvation

stage 2: as soon as positive G is restored, fuel flows around the floater and down into the engine at increased rate (since the floater, well, floats in the fuel and thus descends slower to its original position ), resulting in too much fuel drowning the engine out, signified by the tell-tale signs of black smoke that accompanies an incomplete burn

I actually like it quite a lot the way it's done in CoD. Between the individual aircraft quirks, the extra details and restrictions and the all-around higher level of challenge in all flyables, i feel like flying for the allied team much more often than i used to in IL2.

[609_Huetz]

It's not way too much, but it is overdone indeed (also showing in the video) when he noses up and rolls over, he is forcing his nose straight for a second. In COD it would start cutting out in this stage already.

[winny]

I don't think it's wrong, any ammount of negative G in early Spitfires causes the engine to cut with very little delay. That's why it was such a problem. There is no inbetween.

If anyone can prove otherwise I'd like to see it.

I also just read an account where a RAF pilot deliberately nosed down to produce a cloud of black smoke to fake being hit when he was bounced.

[SEE]

Originally Posted by Blackdog_kt

Well, it seems more forgiving than IL2 to me, at least the engine doesn't completely turn off. ......

I actually like it quite a lot the way it's done in CoD. Between the individual aircraft quirks, the extra details and restrictions and the all-around higher level of challenge in all flyables.

+1