Spitfire IXe automatic radiator flaps not working

[Talon_]

The Spitfire's automatic radiators now fail to open adequately at high altitude, causing overheat and coolant loss.

 

Even at +25lbs of boost under "tropical summer conditions" the Spitfire LF IXe did not suffer from overheating in this manner:

 

 

[Kurfurst]

On 9/30/2018 at 1:24 PM, Talon_ said:

 

Even at +25lbs of boost under "tropical summer conditions" the Spitfire LF IXe did not suffer from overheating in this manner:

 

 

 That is actually a lie as I have the full report and it does start to increase temperaturr overheat, even though the cooling trials were done at very low temperatures (+7 Celsius outside temperatere on the ground level IIRC) and very low starting engine coolant temperatures.

[unreasonable]

+25lbs is a red herring here since we do not have it - the issue is that in the current incarnation of the BoX Spitfires, unlike their real counterparts, climbing to the ceiling at rated power is impossible since the aircraft starts to lose all it's coolant - out of the radiators, bizarrely, although the relief valve was on the nose.  So either radiator opening is modeled incorrectly, which I doubt, since they were operated by a thermostat, or the system is incorrectly pressurized. 

 

Is there anywhere a report, PN or engine manual that says that pilots should use lower temperature limits for higher altitudes in the Spitfire?  This seems to be the case in the 109, for example, although in the game they suffer no consequences for maintaining SL temperatures at high altitudes; but I cannot see any mention of this in the PNs for any mark of Spitfire.  Nor so far has anyone come up with a specific document stating the SL pressure of the Spitfire coolant system or the pressure limit of the relief valve.

 

Something is seriously wrong since the Mk.IX cannot be flown at high altitude in it's current state.

 

 

 

 

Edited October 3, 2018 by unreasonable

[CountZero]

up high radiator flaps simply dont open on automatic, engine is overheating because they are fully closed and dont open.

If you manualy open them to 100% ( cant adjust them manualy) all is ok.

Something is clearly wrong with how automatic flaps work after new temp calculations, how this ased testing phase i wonder its iconic airplane not some rearly used one.

[Kurfurst]

There is difference between absolute maximum temperatures and maximum temperatures allowed for a short period only.

 

It may be that the temperatures referred to in the manual are allowed only for short terms, like 5 minutes and in effect the coolant is already boiling away at those temperatures.

 

Comparison with other types is rather meaningless without knowing the circulation rate, total coolant volume and heat exchange capacity of the radiators themselves for example. The Merlin also used a 70/30 glycol / water mixture IIRC, and as such it higher boiling point bit also noticable lower hear transfer capacity than the usual 50/50 coolant mixtures.

[unreasonable]

38 minutes ago, 77.CountZero said:

up high radiator flaps simply dont open on automatic, engine is overheating because they are fully closed and dont open.

If you manualy open them to 100% ( cant adjust them manualy) all is ok.

Something is clearly wrong with how automatic flaps work after new temp calculations, how this ased testing phase i wonder its iconic airplane not some rearly used one.

 

Right, but they are not opening because the temperature does not reach 115 C.  If that is how the radiators work -  with a thermostat as described in the manual - then the problem is not that the temperature is too high, but that [ edit - the coolant is boiling at too low a temperature, because] the pressure in the system is also too low.

 

The absolute maximum for Spitfires tended to be 135 C - at which point they may have been blowing off through the relief valve, but we have yet to see any documentation.  If the relief valve operated to relieve pressure at that temperature (135) at sea level,  it would still not open at 115 C at altitude.  (I think - let some engineer get this right  ) 

 

Basically I am questioning the assertion that Spitfire pilots would have to watch their temperatures with an altitude specific set of limits in mind, given that there is nothing in the aircraft's documentation I have yet seen.  If they actually had to do this, where is the evidence?

 

As for comparison with other types: if Bf 109 coolant temperature gauges have on the markings for SL, 5km and 10km, which they all do up to the G14 IIRC, then that is pretty clear evidence this was a real issue for 109s and pilots were expected to watch for this.  There are no equivalent markings on Spitfire gauges, the maximum temperatures were much higher than for 109s, which means that the relief valves operated at higher pressures and there is nothing in PNs about this.

 

In addition, having coolant pour out of the radiators  - including the intercooler and oil cooler radiators - is just silly.  

 

 

Edited October 3, 2018 by unreasonable

[Kurfurst]

Well, before jumping to various conclusions regarding wheter the system is modelled well or not, perhaps it would be not in vain to establish first how it is supposed to work in the first place on a real aircraft.

 

Meaning that at the very least, radiator kinematics control are to be obtained and temperature curves for the engines are to be presented first.

[CountZero]

i have hard time beliving that in real airplane that is made for high altitude with m70 engine would have automatic radiators set in a way that they dont work on high altitude, and are always 0% no mather if it will brake your engine doing so, whats their point of radiators or auto control of them then why they even made them?

[unreasonable]

@VO101Kurfurst

In an ideal world I would have no problem with that - for all aircraft.  Do you have these?  Let us not make the perfect the enemy of the good: we do not need a FBI investigation to see that the current implementation is problematic. 

 

Meanwhile, the fact is that we now have a Spitfire that cannot be flown by the book without it's cooling system blowing up.  This seems implausible. If there is doubt about how it worked then the Spitfire should be put back to it's previous state until the matter is clarified.

 

At the very least the developers should explain how they came to the conclusions that they have in the current model, so that if it is correct now all the engineers posting that it is not can continue their education.

 

 

 

[Talon_]

7 hours ago, unreasonable said:

+25lbs is a red herring here since we do not have it

Not yet! I am having a very productive conversation about that though

 

Radiator flaps are fully automatic and should not require any babysitting from the pilot at any point. The pushbutton switch is for ground testing only and is not for use in flight.

 

 

 

 

1 hour at 125 degrees, +12 boost.

Consider that after 1 hour at +12lbs boost, the Spitfire's fuel reserve is entirely drained. This means the Spitfire can run at 125 degrees with no problems whatsoever for the entire flight.

 

 

See here, climbing power (1hr limit) is limited by fuel capacity not engine endurance.

 

 

 

Edited October 3, 2018 by Talon_

[Talon_]

Hopefully this bug can be fixed soon, more information here for correct coolant pressures. Looks like the Spitfire system had a lot more pressure than a Yak etc: