do the engine gauges still work properly?
 

hey guys.
i just flew a mission where my bf E4 took a few hits, and i saw, that i lost liquid.though i dont know which one.could be water or fuel.nevertheless, i observed my engine gauges, and fuel amount didnt decrease,and the temps were in the healthy range, and the pressure of fuel and oil were at their normal levels.
after about 5 to 10 minutes, the engine began to stutter badly, oil was suddenly all over my canopy, but still all the gauges showed the normal values.
finally i ditched into the channel.some few seconds before i got wet, the fuel pressure dropped very promptly to zero, although the fuel amount still showed 50%....

is this a correct behaviour of the gauges?

i flew the mission offline, and i wanted to provoke such a situation, with the actual aim, that as soon i would have observed a change in the temps,pressure or amount values to try to make it back.

i remember a few patches ago, that i often recognized changes in the pressure values, when the plane was damaged, and as soon i observed such irregularities, i headed back, often with success.the values often decreased slowly, so i had a chance to fly home.
but i havent seen this behaviour for some time now, so i wanted to ask if its still working that way.

i had indeed a fuel leak and the instrument kept telling normal fuel values. I cutted the mission realativetly soon, so i didnt check if i ended my fuel before handle rreached 0

The ranges are all off as well. For instance at higher altitudes, according to the Messerschmitt manual, the coolant would be overheating at the indicated temperature we get in the game.

In the game you don't see the temperatures drop at higher altitude, which they should because it's colder up there and as the boiling point of water drops with altitude your coolant would be turning to steam at the indicated levels shown.

nice finding xnomad.
i think that we really can speak of CEM, these features should be included.

The first time might be right, but isn`t the coolant system pressurized and that because the boiling point independent from the altitude?

No expert here, just guessing.

If it wasn't pressurized then it would leak all over the place. Anything that contains a liquid or gas that is not meant to escape will be pressurized. Balloons, cans of soda, your air mattress. All pressurized.

I thought coolant was in a closed looped system under pressure and atmospheric pressure would not have any affect?

Interesting if it does.

Oops I didn't mean to come across as an expert either I'm just going by the Messerschmitt chart that shows that the temperature limits are lower the higher you get. Going by that I figured it must be because the boiling point changes with altitude.

However you are right the system would be pressurized so I'm not sure why the limits are lower.

I'm no airplane engine expert, but I do know plenty about automotive engines. The reason the coolant system is pressurized is because it raises the boiling point almost 50 degrees F (212 + 50 in F). And that should be completely separate from atmospheric pressure, as the cap, overflow system, and t-stat(s) all play an important role in maintaining that coolant equilibrium.

No. It's pressurized to raise the boiling point of the coolant. It has nothing to do with keeping it from leaking. Once cap pressure is overcame, it will siphon (leak) right on by the radiator until it can be sucked back in. You could take a huge radiator, without a cap, and leave the level of coolant lower and the system will never leak (no pressure), but it won't be as efficient.

I'd have to agree with you. I don't see how it could be effected, but I don't know.



@All - I don't know how much better cooling you'll get with high altitude conditions. Obviously it will help, but remember the coolant is there to keep the internal engine (where combustion occurs - a temperature that only slightly varies (lean/rich) in the combustion chamber) Outside air helps to cool the coolant obviously, through radiators, but that cold outside air also makes the engine need less fuel at altitude (less air density/less volume of oxygen) and colder air + less fuel = hotter combustion temps which = warmer base engine to cool.

Again, I have no idea how much the efficiency of cooling is higher altitude (super cold air) on a tiny radiator, but so much else is reliant upon the water pump and combustion chamber temp as well.

Would be neat if someone could find an article on it!

this thread really starts to get interesting!thx for all your information.

Actually, i'm pretty sure the Stuka has different temp limits per altitude band due to an unpressurized or "not pressurized enough" system (limits are stated in the game's manual).

There are also some tick marks on the 110's water temp gauges if you zoom close enough, they specify the max allowable temp for a variety of altitudes. ;)

That's why I'm confused by the bf 109's cooling chart in the Messerschmitt manual for the Emil. These are the temperature limits for coolant at altitude:

http://109lair.hobbyvista.com/techre...als/bf109e.pdf

0 km -> 100 C
2 km -> 95 C
4 km -> 91 C
6 km -> 87 C
8 km -> 82 C
10 km -> 78 C

It's similar to water's boiling point at altitude but about 10 degrees off. So it almost appears to be subjected to atmospheric pressure changes. However, as mentioned before in this thread, to be contained in the system it would need to be sealed, and thus pressurised, otherwise it would leak (especially in a fighter that can be found at different attitudes e.g. upside down). So there must be another reason for these temperature limits?

The manual also states that the coolant is merely water with some rust inhibitors and that 30% glysantin/glycol is only added when temperatures are around freezing.

The schematics for the cooling system show bleed valves for over pressure. The circulation pump seems to be part of the engine or there is a convection process that circulates the coolant?

Is it something to do with that air doesn't transfer heat as efficiently at altitude because it is less dense? However in that case the temperatures limits shouldn't need to change you would just have to open the radiator more.

Or are they precautionary limits as it takes longer to cool at lower air densities? However, I'd imagine the colder air would make up for this? I don't know I work in IT this is all beyond me.

My idea about the lowered allowed temps at alt. is simple that the thinner air can't transport enough thermal energy.

So, as the outlet-temperature of the radiators is the important value here (it is known how much thermal energy will be produced)
the pilot must control the indicated inlet temperature to a point where the radiator is able to cool the coolant to the needed max. outlet-temp.

Just an observation with the 109 coolant system. When taking a hit I've noticed the coolant escaping and when finally all coolant being evacuated, the water temp gauge would show it completely off the right side(as high as it could be).

In my observations of real life coolant failures (in automobiles however) this is the exact opposition. The gauge should be showing the minimum temperature.

That depends where the sensor is mounted, at the engine -> heating up without cooling, or in the coolant circuit -> cooling down without fluid to transfer the heat.