Engine idle speed(cold starts)

[Grahamh1701d]

Hi,

I am just wondering about the idle speed of the DB605 engine especially when cold. Is it correct that the engine will start from stone cold with the throttle at idle? Surely it would cut out or refuse to start? The tickover speed also seems very low? I believe the P-51 and FW190, (possibly less so on the FW190 because of its more sophisticated engine control unit), have the same issue. I know the Accusim P-51 has cold starts modelled correctly it won't run at idle properly until warmed through. I am just wondering if this is correct or not and will it be fixed if not? I don't want to start a debate on which sim is better. Thank you.

 

Regards Graham

[Altflieger]

https://www.youtube.com/watch?v=7Sz5t-m9IOE

[Grahamh1701d]

So the throttle should be set to a start position on the throttle quadrant which when the engine starts should be at 1000rpm and that is the warm up speed and will not run smoothly below that until warmed through a little? In DCS at the moment the 109 will start from stone cold in the fully idle position at lower than the lowest point on the rev counter at about 400rpm maybe less.

[Altflieger]

In game, you'll have to ask Yoyo, but starting with the throttle closed would seem to be somewhat odd.

The main thing is not whether the engine starts but the need to keep the revs down once started so as not to overload the oil pump (I assume) and save engine wear. If it's cold, the oil will be thicker hence the warning in the video to immediately check that the oil pressure is within limits, if not shut the engine down.

The prop would be pulled through by hand 3 or 4 times to get some oil to the main bearings (inverted engine) before starting to prevent engine wear. The whole run up period is to get the oil circulating properly, which unless gauges say otherwise, it will be when the oil temp reads 40 degrees.

When I start ingame I set the throttle lever to align with red ZU marking of the fuel pump lever, when it starts u\min is about 600 and I raise it gently to about 1200 to heat it up a bit quicker, no problems so far but then only about half a dozen starts so far :)

[Grahamh1701d]

I suppose the point I am trying to get at is whether difficult starting and rough, uneven and even cutting out at idle or very close to idle throttle position is modelled in the simulation in cold weather as would be the case in real life. The same way a car engine with a carburettor will not start in the cold weather without an enrichment device (choke) and fast idle until the engine has ran for a minute or two to warm through a little.

[Grahamh1701d]

I have just done a cold start from ramp mission with the ambient temperature at -30 degrees. The engine will start no problem at complete idle and the coolant temperature is up to nominal within a minute. I am sure this cannot be right. The engine should be very reluctant to run at idle at this temperature when it is stone cold and the coolant should take a while to warm. I can only assume from this that the ambient temperature has no effect on the engine from a cold start situation.

[QuiGon]

I think you're right. Well, that's really disappointing :(

[NeilWillis]

It is still in Beta, would you have preferred to wait another month for all these minor details to be added before release?

 

I don't think so!

[sobek]

The engine slow model in DCS is not finished. Some time ago Yo-Yo mentioned that he finally had the ressources to work on it again, but it seems that this hasn't come to fruition.

[Grahamh1701d]

Excellent. It is good to know that is something that is being thought about to be added at another time.