wip Over-cooling

[Yo-Yo]

2 hours ago, grafspee said:

Dcs spitfire manual says that thermostat is set at 80C and below this temp all coolant is directed in to pump inlet bypassing radiators. 

So ED should make up mind on this matter. If thermostat is set at 50C manual should be corrected or set thermostat to 80C.

I don't believe that 50C is ok for engine, low oil temp favors oil dilution with fuel and water.

If every manual states that thermostat is set to 80C why not do that?

P-51 may have the similar engine but cooling system is done way different. Mustang regulates temp via shutter doors and spitfire via thermostat and shutter doors which has 2 positions only, full open and normal operation position.

 

 

Nope... the best working temperature for the engine is 90 - 115C, because high coolant temperature sufficiently increases radiator effectiveness and even increases drag. And the shutter in Spitfire tries to maintain the temperature in this range. The regulator itself is simpler than in P-51 but it works. The thermostatic valves either in P-51 or in Spitfire plays another role limiting minimal coolant temperature.

[Davee]

1 hour ago, Yo-Yo said:

60 C is good to apply full power, it is not a matter of faith, because it is from the manual...

Please, show the original manual with 80C, and we fix it.

Please attach the track/

 

I'll make a new one and send.

[grafspee]

1 hour ago, Yo-Yo said:

Nope... the best working temperature for the engine is 90 - 115C, because high coolant temperature sufficiently increases radiator effectiveness and even increases drag. And the shutter in Spitfire tries to maintain the temperature in this range. The regulator itself is simpler than in P-51 but it works. The thermostatic valves either in P-51 or in Spitfire plays another role limiting minimal coolant temperature.

This is what i'm talking about. If thermostat is set to 80C and at temps below, it cuts off radiators so how it is possible to temp goes below 60C in flight at moderate power ??

And i just said that coolant temps at 50C are not good for engines. And you said in previous post that 50C is ok because 60C is minimal temp for take off. 

Thermostat valve will maintain 80C as manual says until thermostat valve reach maximum opening, then thermostat is removed from equation. Temps will go up until radiator effectives become high enough to stop temp rising. So at low power setting expected coolant temp should be 80C not 40C or 10C

 

Edited December 19, 2022 by grafspee

[Yo-Yo]

Just now, grafspee said:

This is what i'm talking about. If thermostat is set to 80C and at temps below, it cuts off radiators so how it is possible to temp goes below 60C in flight at moderate power ??

And i just said that coolant temps at 50C are not good for engines. And you said in previous post that 50C is ok because 60C is minimal temp for take off. 

Ok, find somewhere in the non-DCS manuals about the thermostatic valve setting for Spit Mk IX and we can discuss the matter. 
 

[grafspee]

[Gunfreak]

The discussion about what temperatures are the correct one. Is interesting enough.

 

But practically speaking,  now after the update. Can I fly the Spit at 2000rpm and 0 boost or even 1700rpm and -4 boost, without breaking the engine?

[Yo-Yo]

Is it relevant to Spit 9 installation or it is R-R recommendation?
As we can see in the Mustang, approx 50C setting was used.
 

2 minutes ago, Gunfreak said:

The discussion about what temperatures are the correct one. Is interesting enough.

 

But practically speaking,  now after the update. Can I fly the Spit at 2000rpm and 0 boost or even 1700rpm and -4 boost, without breaking the engine?

I think, yes, until spark plugs are clean enough.

[Davee]

37 minutes ago, Davee said:

I'll make a new one and send.

Just reflew the Channel Cold Start and Free Flight missions. Now the guages are working. Warm up and climb at 12 lbs boost and 2850 rpm at 180 mph temps at 60 degrees'ish. Cruise at 10,000 ft. maintained 60 degrees'ish and full boost and 3000 rpm diving to the deck and maintaining for 4 minutes maintained about 90 degrees coolant and oil temp was just above 80 degrees. Rad was in auto.

I am happy and cannot understand why yesterday the guages moved very little. Yesterday's missions were flown just after the upgrade install.

Thanks for listening.

Cheers

 

[grafspee]

@Yo-Yo As this manual says, it may be installed, but if it is setting is around 80C

And think that those guys who wrote DCS manual, took this thing for thin air.

What i know is that not all mk IX had thermostat in cooling system, just read that in manual

Edited December 19, 2022 by grafspee

[NineLine]

6 minutes ago, Davee said:

Just reflew the Channel Cold Start and Free Flight missions. Now the guages are working. Warm up and climb at 12 lbs boost and 2850 rpm at 180 mph temps at 60 degrees'ish. Cruise at 10,000 ft. maintained 60 degrees'ish and full boost and 3000 rpm diving to the deck and maintaining for 4 minutes maintained about 90 degrees coolant and oil temp was just above 80 degrees. Rad was in auto.

I am happy and cannot understand why yesterday the guages moved very little. Yesterday's missions were flown just after the upgrade install.

Thanks for listening.

Cheers

 

Sometimes old missions require resaving, not sure if that was it, but something to keep in mind. 

[71st_AH Rob]

49 minutes ago, grafspee said:

@Yo-Yo As this manual says, it may be installed, but if it is setting is around 80C

And think that those guys who wrote DCS manual, took this thing for thin air.

What i know is that not all mk IX had thermostat in cooling system, just read that in manual

 

The Pilots Notes for the Spitfire Mk IX, XI and XVI 3rd edition, covering aircraft with Merlin engines 61, 63, 66, 70 and 266. On page 9 Para 7, states that only early aircraft had the thermostat.

So what constitutes an "early aircraft"?  Well the early Mk IX were fitted with the Merlin 61 or 63 presumably.  The 66 was fitted to the LF Mk IX that we have in 1943, the 70 to the HF Mk IX and the 266 was the Packard Merlin that was for the Mustang but was different enough that it got it's own designation and when fitted to a Mk IX instead of a Mustang it was renamed a MK XIV.   Our LF MK IXc is an early Merlin 66 aircraft by the look of it and there may have been some that were equipped with a thermostat but most likely ours didn't, ours does look like a MK Vc that was converted though so anything is possible.

The other interesting part of this paragraph is the note the the radiator flaps open at 115c.   In Part III of the manual, para 51 on pg 30 the Min take off temp is 60c so any thermostat would likely be at least that temp, however in Part II para 37 "Testing the engine and services while warming up" :

So it is most likely that you would be well above 60c before you finished taxing to the runway anyway.   Also interesting is the engine limitations on pg 30, Part III, para 51 the max take off temp to 1000 ft is 135c which would lead one to believe that the engine heated up quite quickly.

Since most IC engines are happy around 90c -105c and the radiator flaps open at 115c I think the main problem was overheating not over cooling.

So what do we know?

Fact: Automatic radiator flaps opened at 115c

Fact: Not all MK IX had thermostats

Fact: the thermostat if fitted to a Merlin 61,63, 66 or 70 wold be 80c

Fact: at MAX Continuous temp limit was 105c with 115c permitted for short periods

What can we deduce?

Deduction: Automatic radiator flaps likely closed somewhere close to, but under 115c, maybe between 90c and 105c?

Deduction: they stopped fitting the thermostat to the MK IX because it was not needed as the engine warmed rapidly and keeping it cool was the primary concern

Deduction: Thermostats were not fitted to the Merlin 66 equipped MK IXc

 

Conclusion: our spitfire should not suffer from over cooling and the operating temp should probably not drop much below 90c or Supermarine and Rolls Royce would have taken steps to change the design to ensure that it did not, i.e. add a thermostat to the system.

[grafspee]

@71st_AH Rob Agree, but in that case spit should not have thermostat at all, in flight by closing throttle we should be able to over-cool engine.

Thermostat definitely would not be removed if spit had any issues with over-cooling.

Conclusion: cooling model is wrong then

Edited December 19, 2022 by grafspee

[Andy1966]

Well said Rob, I was also wondering about were the temp sender/sensor is located. It seems to me it is in the inlet side of the coolant pump. It seems to me I read that in a manual some where, but I could be mistaken. I will go try to find it.  I made a few flights to 20000 ft or so and the temp seemed to only fall to 60 or so, and then stop dropping. I do distinctly remember a note that it may be necessary to increase power temporarily to maintain a safe coolant temp. like Yo-Yo said, the biggest danger should be fouled sparkplugs, barring any cooling system malfunction.

 Edit: I went and looked at the DCS manual and the thermometer is in the outlet of the header tank, before the thermostatic valve. I will go check the real maintenance manual now.

Edited December 20, 2022 by Andy1966
looked at manual

[303_Kermit]

Spitfire MkIX In flight cockpit cam. Temperature gauge visible form time to time. 
2:17 coolant temp ~90° Idle before T-off (7 lbs/in²)
2:50 (In climb) coolant temp ~ 100° (7 lbs/in²)
3:02 descending 4000ft/m, 300mph coolant temp ~85°-90°

5:06 level flight (longer time period) 210mph coolant temp. ~90°-100° (+6 lbs/in²) / oil temp. 60°

6:21 level flight 220mph coolant~90° oil ~60° (+1 lbs/in²)

With my best regards
Kermit

PS. I recon ... there's no "milk" spilled on the windshield as in DCS is...
 

 

Edited December 21, 2022 by 303_Kermit

[grafspee]

@303_Kermit Looks like thermostat doing the job in real plane

Temp does diver only by 10C between different flight phases climb, dive , cruise. 

Edited December 20, 2022 by grafspee

[Skewgear]

I think grafspee and Yo-yo are talking about two separate things.

Grafspee talks about the 80C minimum *oil* temperature. Yo-yo talks about the minimum *coolant* temperature.

On the Packard V-1650-3 and -7 engines, which are licence built Merlin derivatives, the minimum coolant temperature is 60C because at that temperature the coolant return circuit warms the carb air intake enough to prevent carburettor icing on takeoff. I don't yet know for certain but I'm pretty sure the Merlin 66 has the same automatic carb heat arrangement.

We are unhappy at the Spitfire oil temp and pressure because according to the Pilot's Notes manual for the real aircraft, oil temp should not fall below 80C due to a thermostatic valve in the *oil system* that cuts out cooling below that point. The schematic for this is in the DCS Spitfire IX manual in this thread.

Edited December 20, 2022 by Skewgear

[Wiggy]

[Yo-Yo]

We will implement 80C for the thermostatic valve as we are making Typical plane. For Mk IX we need Mark IX relevant information.

[Wiggy]

Does The Fighter Collection not have good information on the mk.IX that Nick could tap into?

The above is from an official publication for the Merlin 66, so relevant to the mk.IX. Revision dated May '44. Can send the whole document if needed. Hope it helps.

 

[Yo-Yo]

Yes, I have one. But these engines were used for very different planes of different manufacturers, and, as far as you can see, for the P-51 was used very different temperature.
I am trying to get relevant info from TFC.

18 hours ago, Skewgear said:

I think grafspee and Yo-yo are talking about two separate things.

Grafspee talks about the 80C minimum *oil* temperature. Yo-yo talks about the minimum *coolant* temperature.

On the Packard V-1650-3 and -7 engines, which are licence built Merlin derivatives, the minimum coolant temperature is 60C because at that temperature the coolant return circuit warms the carb air intake enough to prevent carburettor icing on takeoff. I don't yet know for certain but I'm pretty sure the Merlin 66 has the same automatic carb heat arrangement.

We are unhappy at the Spitfire oil temp and pressure because according to the Pilot's Notes manual for the real aircraft, oil temp should not fall below 80C due to a thermostatic valve in the *oil system* that cuts out cooling below that point. The schematic for this is in the DCS Spitfire IX manual in this thread.

 

As far as I can see from the reports, radiator inlet temperatures were recorded as low as 73C, and, regarding the radiator outlet temp, radiator was fully effective.  If it were 80C valve it would be seen.

[grafspee]

19 hours ago, Skewgear said:

I think grafspee and Yo-yo are talking about two separate things.

Grafspee talks about the 80C minimum *oil* temperature. Yo-yo talks about the minimum *coolant* temperature.

On the Packard V-1650-3 and -7 engines, which are licence built Merlin derivatives, the minimum coolant temperature is 60C because at that temperature the coolant return circuit warms the carb air intake enough to prevent carburettor icing on takeoff. I don't yet know for certain but I'm pretty sure the Merlin 66 has the same automatic carb heat arrangement.

We are unhappy at the Spitfire oil temp and pressure because according to the Pilot's Notes manual for the real aircraft, oil temp should not fall below 80C due to a thermostatic valve in the *oil system* that cuts out cooling below that point. The schematic for this is in the DCS Spitfire IX manual in this thread.

 

I'm not talking about minimal coolant or oil temp, i'm talking about thermostatic valve in coolant circuit which divert coolant entirely to pump inlet by passing radiators at coolant temp below 80C

23 minutes ago, Yo-Yo said:

As far as I can see from the reports, radiator inlet temperatures were recorded as low as 73C, and, regarding the radiator outlet temp, radiator was fully effective.  If it were 80C valve it would be seen.

Remember that RR manual says that thermostat ,if mounted, were set to approximately 80C, so small variation could happen. 

[Yo-Yo]

In P-51 it is mounted and  maintenance manual gives directions unambiguously that "small variation" is about minus 30C from 80C.. And the manual contains instruction how to check this value. But, anyway, as I have EXACT info about Spitfire 9 thermostat, I will change, if necessary.

[Wiggy]

Gotcha. Well main point is the engines should no longer seize or fail when run for long periods at economy cruise, this being the original point of the thread.
 

Thanks for the updates:)

[Pyrocumulous]

Attached is a track of the Spitfire engine degrading and failing at around +4 boost, 2200rpm while crossing the Channel at 20,000' with +1 degree surface temperature. This is with DCS 2.8.1.34667.1 Open Beta in Beware Beware Beware sortie #6. I don't know much about historic accuracy of the thermostats in these planes, but if they behaved like it's modeled, the war would have had a different outcome.

https://drive.google.com/file/d/1plguA4p1LcXSquDVHZbm6z6uGsITS1kd/view?usp=share_link

[Davee]

7 hours ago, Pyrocumulous said:

Attached is a track of the Spitfire engine degrading and failing at around +4 boost, 2200rpm while crossing the Channel at 20,000' with +1 degree surface temperature. This is with DCS 2.8.1.34667.1 Open Beta in Beware Beware Beware sortie #6. I don't know much about historic accuracy of the thermostats in these planes, but if they behaved like it's modeled, the war would have had a different outcome.

https://drive.google.com/file/d/1plguA4p1LcXSquDVHZbm6z6uGsITS1kd/view?usp=share_link

Flying the P51 in long climb to 25,000 within advised engine settings, had to watch temps and switch rads open and auto as oil and coolant temps climbed to max on a continual basis. Climb speed 200 mph. RPM 2700. Boost 45 lbs. (maintained 45 lbs as altitude and engine boost kicked in)  Mission was Blue Nose Bastards . . . . by Reflected.

Edited December 23, 2022 by Davee