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92 Sqn. Philstyle (QJ-P)
Apr-17-2013, 06:09
I had quite a lot of trouble trying to get a Spitfire 2a to overheat last night. This was on the ATAG server. Have the realism settings been changed recently?

I got Airborne from Eastchurch,

RPM at 3000
Boost +12lb (100% throttle)
Radiator to 70% open

Normally I'd reduced to 2800rpm, or 2600rpm after a few minutes flying. However, I was deliberately trying to make the engine pop on this occasion.
Got all the way to Hawkinge, 3000rpm the whole way... still no overheat despite 135 water temp and 100 oil temp.

Flew around at 18,000ft for another 10 minutes at the same engine settings after climb up.

What am I doing wrong, why wouldn't she overheat?

I've parked a spitfire on the ground before (post TF patch) with 115 water temperature and she boils over in no time at all - at 120.
thr patch notes indicate that she should have blown up much earlier too.

DGC338
Apr-18-2013, 00:20
100 degree oil temp is fine & 135 degree rad temp is at the upper limit but not excessive for the Mk IIa. See the Flight manual.

http://www.theairtacticalassaultgroup.com/wiki/doku.php?id=spitfire_iia

The Mk IIa has different limits as it is a Merlin XII as opposed to the Merlin III engined Mk I.

LG1.Farber
Apr-18-2013, 03:44
I guess the Germans didnt use any coolant then, just pure water as the 109's water blows the rad at 100. Oil max is 105. I wonder what all of the aircraft have for coolant max's and why they are so different?

92 Sqn. Philstyle (QJ-P)
Apr-18-2013, 03:59
I guess the Germans didnt use any coolant then, just pure water as the 109's water blows the rad at 100. Oil max is 105. I wonder what all of the aircraft have for coolant max's and why they are so different?

I understand that with the 109f they pushed the tolerance up to 115 degrees...

Perhaps is has something to do with where the temperature measured from. If the RAF fighter's temperature is measured just before the water goes into the radiator, and the 109 temperature is measured just after the water leaves the traitorous, that might explain the differential.

Kling
Apr-18-2013, 04:16
I understand that with the 109f they pushed the tolerance up to 115 degrees...

Perhaps is has something to do with where the temperature measured from. If the RAF fighter's temperature is measured just before the water goes into the radiator, and the 109 temperature is measured just after the water leaves the traitorous, that might explain the differential.

The spitfire radiator system is pressurized and therefor boils at a higher temperature and if memory serves me well, it was also a mix of water and coolant. Where as the german planes had unpressurized radiator system and their radiator system should boil at a lower and lower temperature the higher the plane goes. The boiling point of water for example at 7000m is 77 degrees Celcius. This is however not modeled in the game and the boiling point for axis planes in game is always 100 degrees Celcius. I think this is the main reason the 109 has two big radiators where as the spit only has one. I read somewhere that the germans were jealous when they saw a captured Spitfire and the efficiancy of its coolant system.

92 Sqn. Philstyle (QJ-P)
Apr-18-2013, 04:24
Thanks Kling.

Gromit
Apr-18-2013, 04:55
The spitfire radiator system is pressurized and therefor boils at a higher temperature and if memory serves me well, it was also a mix of water and coolant. Where as the german planes had unpressurized radiator system and their radiator system should boil at a lower and lower temperature the higher the plane goes. The boiling point of water for example at 7000m is 77 degrees Celcius. This is however not modeled in the game and the boiling point for axis planes in game is always 100 degrees Celcius. I think this is the main reason the 109 has two big radiators where as the spit only has one. I read somewhere that the germans were jealous when they saw a captured Spitfire and the efficiancy of its coolant system.

When you say "unpressurized", you mean at atmospheric pressure?

if so that means the boiling point of the coolant will drop rapidly with height leading to overheat very quickly, surely it means a lower pressure system (possible at 1bar), seeing as the water pump alone adds pressure to the system and as far as I know the 109 has pressure relief valves?

Gromit
Apr-18-2013, 04:59
I understand that with the 109f they pushed the tolerance up to 115 degrees...

Perhaps is has something to do with where the temperature measured from. If the RAF fighter's temperature is measured just before the water goes into the radiator, and the 109 temperature is measured just after the water leaves the traitorous, that might explain the differential.

That makes a huge difference to the actual temp in the engine Phil, when I raced cars in testing we measured the difference between the input and outlet temps of the radiator to get the cooling as low drag and efficient as possible.
We often saw input temps as high as 108dC (our set limit) and outputs as low as 65dC, showing us we were overcooling, ideal was 95dC.

if a 109 is showing 100deg out of the rad the input temp, and therefore the actual temp in the engine block will be a lot higher!

Kling
Apr-18-2013, 05:04
Read this thread... It gets more specific about the radiator and overheating the further down you read!

http://theairtacticalassaultgroup.com/forum/showthread.php?t=3827

Edit: Hm i dont know why it doesnt show as a proper link... :/
Well just copy paste it then...

Gromit
Apr-18-2013, 07:04
Unfortunatly it doesn't clarify the definition of unpressurized, it can't be unpressurized as this would denote open to atmospheric pressure, it must be set at 1BAR absolute at sea level?

either way , whether its at 1BAR or 1.5 BAR normal working pressure, once ruptured the system will suffer cavitation in the pump reducing flow and also then be operating at ambient pressure, if your up high and your system is ruptured your going to boil quicker than low down!

overheat in an engine should be seen as an increasing loss of power, the hotter an engine gets the more expansion of reciprocating and rotating parts, increasing friction, loss of tension in piston rings losing compression and lower detonation threshold in the cylinders, also increased charge temps reduce charge density lowering output even further!

you know bugger it, it's waay to complicated to try and model accurately, 2mins 10 will do!

Kling
Apr-18-2013, 07:35
Unfortunatly it doesn't clarify the definition of unpressurized, it can't be unpressurized as this would denote open to atmospheric pressure, it must be set at 1BAR absolute at sea level?

either way , whether its at 1BAR or 1.5 BAR normal working pressure, once ruptured the system will suffer cavitation in the pump reducing flow and also then be operating at ambient pressure, if your up high and your system is ruptured your going to boil quicker than low down!

overheat in an engine should be seen as an increasing loss of power, the hotter an engine gets the more expansion of reciprocating and rotating parts, increasing friction, loss of tension in piston rings losing compression and lower detonation threshold in the cylinders, also increased charge temps reduce charge density lowering output even further!

you know bugger it, it's waay to complicated to try and model accurately, 2mins 10 will do!

yes if you were running full power I would happily accept this.
But even if you shut the engine down and glide and dive, the engine will fail after 2mins 10secs.
I could easily see pilots reducing power diving home to cool the engine as much as possible in order to just get home.
I think closer to 4mins would be a good compromise then.

Gromit
Apr-18-2013, 07:50
at full power the engines going to burn pretty fast, oil fire would be a serious danger, no way an engine producing over 1000HP could survive 2 mins, these are big engines and quite fragile, overheat them and the blocks will warp and distort simply due to their length and shape, throwing bearings and suchlike out of tolerance, to make power you have to burn fuel and air, if you burn the fuel and air you produce more energy and that goes hand in hand with heat, more energy = more heat!

even at low rpm these things are generating a lot of heat!

to get back your going to have to do what the rest of us do, and that's throttle back, drop the prop pitch and come in on a gentle glide slope (if you have the height, otherwise bail), even then I often cut the motor as it's rattling it's nuts off and land dead stick!

Most blue pilots get damaged and stick around trying for more kills, if you increase the limit to four minutes your just going to have 109 pilots with damaged planes trying for more kills for four mins instead! a real pilot wouldn't do that and other than venting them it's already too difficult to bring a 109 down, last night I fought a guy over the ships by littlestone, I got a solid burst into his wing in a head on, he zoomed back up , throttled back and made it home, so someones doing it right!

Gromit
Apr-18-2013, 11:22
http://109lair.hobbyvista.com/techref/systems/cooling/e_coolant.plan.jpg

Diagram of the 109E cooling system here.

definatly not "unpressurized" as it has two overpressure relief valves, so it's a closed loop recirculating system!

Kling
Apr-18-2013, 12:38
at full power the engines going to burn pretty fast, oil fire would be a serious danger, no way an engine producing over 1000HP could survive 2 mins, these are big engines and quite fragile, overheat them and the blocks will warp and distort simply due to their length and shape, throwing bearings and suchlike out of tolerance, to make power you have to burn fuel and air, if you burn the fuel and air you produce more energy and that goes hand in hand with heat, more energy = more heat!

even at low rpm these things are generating a lot of heat!

to get back your going to have to do what the rest of us do, and that's throttle back, drop the prop pitch and come in on a gentle glide slope (if you have the height, otherwise bail), even then I often cut the motor as it's rattling it's nuts off and land dead stick!

Most blue pilots get damaged and stick around trying for more kills, if you increase the limit to four minutes your just going to have 109 pilots with damaged planes trying for more kills for four mins instead! a real pilot wouldn't do that and other than venting them it's already too difficult to bring a 109 down, last night I fought a guy over the ships by littlestone, I got a solid burst into his wing in a head on, he zoomed back up , throttled back and made it home, so someones doing it right!

You have any sources that confirm that only two mins is correct? You say it as you would be sure. Some combat reports claim that pilots would be able to glide, restart and climb and then glide for some time etc etc..

Moggy
Apr-18-2013, 12:45
Not quite a Spitfire but still a Merlin;

"Then at 5.05 p.m., with dusk starting to creep over the Pentland Hills, Gillan took off again, this time with a powerful wind right behind him. For most of the way back to Northolt he travelled at 15,000 feet, the altitude at which the Hurricane was rated to give the best performance. In the enveloping gloom, he had to fly largely using his instrument panel. It was not a comfortable journey, as he recalled: 'At that height I had to use the oxygen apparatus and I had the smell of oil all the way. By Jove it was nasty. I was sick, very sick. I hardly noticed the landscape. I remember looking down and seeing a bunch of chimneys and the dark thread of the river. I thought, "That's Newcastle, that was." I skimmed over a few other towns and glanced down to make sure that my instruments were telling the truth.' By the time he reached London, the sky was black and the outside air freezing. 'There were ten minutes of high cloud to go through when the cabin frosted up and hoar frost formed on the wings. Sometimes I felt sorry I was doing this and thought of the comfort of my men at Northolt. At other times I was glad.' Gillan then embarked on the descent. 'Coming out of a cloud at 5,000 feet, I saw momentarily a red light flashing the letter of my station.' He had accidentally gone a few miles further south of Northolt airfield, but now he turned to make his landing approach. After touching down successfully, he glanced at his watch. It was 5.53 p.m. Gillan had flown the 327 miles from Edinburgh in just 48 minutes, going at an incredible 408.7 mph. In the process, he had shattered the landplane speed world record held by Herman Wuster, one of Messerschmitt's test pilots who had flown an Me 109 the previous November at 379.17 mph.

Sydney Camm's fighter, dismissed by the Air Ministry in January 1934, had not only broken the 400-mph barrier but had become the fastest operational military aircraft in the world. There had been a near gale-force wind behind his Hurricane, but that was scarcely mentioned by the press, which heaped praise on the new machine from Hawker. 'The plane flew half as fast as sound itself,' trumpeted the Daily Mirror on 11 February 1938. 'At such a speed a plane leaving Tower Bridge as a man stepped off the pavement in Trafalgar Square would fly over him before he had crossed the road.' On the same day the Daily Mail gleefully pointed out that the 'latest Edinburgh-Express takes six hours' compared to the 'remarkable' Hurricane flying at 'nearly seven miles a minute'. Apart from shattering the world record, what had also been significant about the flight was the endurance of the Merlin II engine, for Gillan had used take-off boost from the start until the moment he had begun his descent into Northolt. Despite the stress of remaining at 2,950 revs per minute throughout the journey, the Merlin gave no trouble, another indicator of the reliability that would later make it famous during the Second World War.

-Sven-
Apr-18-2013, 14:06
http://109lair.hobbyvista.com/techref/systems/cooling/e_coolant.plan.jpg

Diagram of the 109E cooling system here.

definatly not "unpressurized" as it has two overpressure relief valves, so it's a closed loop recirculating system!

Because of constant volume the pressure would increase when the temperature keeps rising. When pressure is too much, some fluid will be dumped from the cooling system, this should protect the cooling system from damage (leaks,cracks), but I don't know how much fluid could be lost due to the over-pressure, before there is too little fluid left to cool the engine.


About the SpitIIa: I've flown it full throttle 12lb boost for half an hour straight on ATAG last week, flying aerobatically through the skies, making all sorts of maneaovres, taking potshots at Messerschmidts, but it doesn't overheat. Don't try this in any German plane though, you'll regret it.

Kwiatek
Apr-18-2013, 14:19
Because of constant volume the pressure would increase when the temperature keeps rising. When pressure is too much, some fluid will be dumped from the cooling system, this should protect the cooling system from damage (leaks,cracks), but I don't know how much fluid could be lost due to the over-pressure, before there is too little fluid left to cool the engine.


About the SpitIIa: I've flown it full throttle 12lb boost for half an hour straight on ATAG last week, flying aerobatically through the skies, making all sorts of maneaovres, taking potshots at Messerschmidts, but it doesn't overheat. Don't try this in any German plane though, you'll regret it.

Try to climb with it at very slow speed at radiator at half open. You will not keep 3 minutes.

With 109 you could also fly with 5-minutes emergency power ( 1.45 Ata) for all day - if you are not too slow.

It all also depend of altitude - at lower alts there is better colling for engine then at higher alts.

It is not wrong that at lower alts you could fly longer time with emergency power if you are not too slow and with radiator open but when you are too slow you will get quickly overheat. Try DCS P-51 at emergency 67 Hg - it is the same story if you are fast you could fly much more then 5 minutes limit but when you are slow you will get overheat more quickly then 5 minutes. Both CLOD and DCS P-51 is very similar in these.

Robo.
Apr-18-2013, 14:33
Because of constant volume the pressure would increase when the temperature keeps rising. When pressure is too much, some fluid will be dumped from the cooling system, this should protect the cooling system from damage (leaks,cracks), but I don't know how much fluid could be lost due to the over-pressure, before there is too little fluid left to cool the engine.


About the SpitIIa: I've flown it full throttle 12lb boost for half an hour straight on ATAG last week, flying aerobatically through the skies, making all sorts of maneaovres, taking potshots at Messerschmidts, but it doesn't overheat. Don't try this in any German plane though, you'll regret it.

The Merlin XII is supposed to be the best of all engines in game regarding cooling abilities as it had a fully pressurised system and glycol / water mixture rather than pure glycol. But in general, if you keep your speed reasonably high and your rad 100% open, you can fly full power like that in any aircraft, it won't overheat up to FTH.

The current overheating system is still a matter of compromise, but certainly a big step ahead to what we used to have in the stock game, when some aircraft would not overheat at all and could fly with wep engaged all day, and some aircraft were extremely fragile and prone to overheat damage even when the power was kept very low. The overheating is now based on the same method for all aircraft, and the temperature limits are now historically correct, reflecting the technical differences eg between the Merlin III and Merlin XII engines.

Another compromise with the unpressurised or partially pressurised systems is that the temperature limit does not drop with the altitude, as this was not possible to implement technically. But all in all I find the new system introduced by TF so much better and I can't thank enough to the guys involved in the looong and booooring testing. :thumbsup:

edit - reading what Kwiatek wrote, that pretty much sums it up imho. DCS P-51 is a good example...

Gromit
Apr-18-2013, 14:59
You have any sources that confirm that only two mins is correct? You say it as you would be sure. Some combat reports claim that pilots would be able to glide, restart and climb and then glide for some time etc etc..

No mate 2 mins is an educated guess made by the game designers not me, it's perfectly reasonable and not open to our own interpretation based upon what we want the plane to be able to do, and yes you can switch off and glide I do it myself, restarting on approach, but you have to be high enough!

I base my assumptions that 2 mins is a reasonable average on my own experience with engines, I raced cars from 1997 to 2008, had a few blow ups, did a lot of development work on cooling and oil systems, and my engines were not producing anywhere near 1000hp, yet they overheated and blew alarmingly quickly!
reality is there's no point fussing about with details as irrelevant as this when we have planes flying through woods and all the other far more important issues to look at!

Gromit
Apr-18-2013, 15:09
[QUOTE=-Sven-;43154]Because of constant volume the pressure would increase when the temperature keeps rising. When pressure is too much, some fluid will be dumped from the cooling system, this should protect the cooling system from damage (leaks,cracks), but I don't know how much fluid could be lost due to the over-pressure, before there is too little fluid left to cool the engine. [Quote]

Yep that's how a ambient 1bar system works at sea level, bear in mind at 5500m air pressure is roughly half that at sea level, so at 5500m your 1bar pressurisation is twice atmospheric and increasing as the air pressure drops as you climb, which is why I was dubious the 109 has an unpressurised system, to be unpressurised the system would have to be running at local ambient, ie, dropping as you climbed, like a car header tank with the cap off, the pressure relief valves above the cylinder heads raises the interesting question what pressure are they set at, because that is the key to understanding the coolant pressure in the system!

Kwiatek
Apr-18-2013, 17:31
I got a few times in Spitfire MK II engine cook during steep climb up to stall speed even not prolonged. I got 2850 RPMs radiator open or 3/4 open and +9 or +12 lbs. It would'nt be strange if it would be sustained climb at very slow speed which take above 2-3 minutes but my engine cook after one short ab. 30 sec steep climb usuallty behind 109 which have no problem with it. In 109 i have never such problem.

Kling
Apr-18-2013, 19:23
No mate 2 mins is an educated guess made by the game designers not me, it's perfectly reasonable and not open to our own interpretation based upon what we want the plane to be able to do, and yes you can switch off and glide I do it myself, restarting on approach, but you have to be high enough!

I base my assumptions that 2 mins is a reasonable average on my own experience with engines, I raced cars from 1997 to 2008, had a few blow ups, did a lot of development work on cooling and oil systems, and my engines were not producing anywhere near 1000hp, yet they overheated and blew alarmingly quickly!
reality is there's no point fussing about with details as irrelevant as this when we have planes flying through woods and all the other far more important issues to look at!

Fair enough, but to be honest, im fairly confidant your cars did not have an as complicated cooling system as a ww2 fighter with radiators made for planes flying constantly at everything between 0-700km/h.
And I wouldnt call it an irrelevant detail, when EVERYONE is suffering from it a few times a day while playing CLOD. I personally would say that "fly through trees" comes alot lower on my list of needed fixes than this. After all we have played il2 1946 for 12 years without "fly through trees" being a game stoper.

gavagai
Apr-18-2013, 22:57
edit - reading what Kwiatek wrote, that pretty much sums it up imho. DCS P-51 is a good example...

Oh my goodness. If Clod had the overheat dynamics of the DCS P-51, many would quit on the spot. Hanging around near stall speed at full power is a big no no. :doh:

Kwiatek
Apr-19-2013, 03:50
Oh my goodness. If Clod had the overheat dynamics of the DCS P-51, many would quit on the spot. Hanging around near stall speed at full power is a big no no. :doh:

You didnt read my second post. Try Spitfire MK II in steep climb to the stall at full power. You will feel like in DCS World :) But not all planes work in similar way in CLOD. 109 had not such problems.

Other way i cant belive that engine could cook so fast in such situation - there is still air overflow by radiator, it could be that way in sustained steep climb at slow speed but with some short ones it shouldnt happend. I think DCS in such situation is also too radical. E.x. 2-3 zooms in P-51 from high speed till stall speed then stall turn could cook your engine even not with emergency power. It give you about 10 second with slow speed - all time zoom take about 20 second from high speed till stall.

Gromit
Apr-19-2013, 04:40
Fair enough, but to be honest, im fairly confidant your cars did not have an as complicated cooling system as a ww2 fighter with radiators made for planes flying constantly at everything between 0-700km/h.
And I wouldnt call it an irrelevant detail, when EVERYONE is suffering from it a few times a day while playing CLOD. I personally would say that "fly through trees" comes alot lower on my list of needed fixes than this. After all we have played il2 1946 for 12 years without "fly through trees" being a game stoper.

Nothing complicated about the 109 system, in fact it's very similar to the layout on most twin radiator single seat race cars, this is 1940 technology!


What you seem to be arguing for is the ability to take damage then be able to fly home, the real issue is don't get damaged if you get damaged get out of there if you can, last night alone I had one wing shot off and a tail removed, both by aircraft diving through the fight with a deflection burst, not a sustained burst but a quick shot , this happens regularly to red planes, yet we have to use large numbers of hits and hope for a pilot kill as 95% of the time even a sustained burst wont slow or degrade a 109's aerobatic capability, if your arguing for more time before engine failure (same for both sides) your going to create the situation where short of a pilot kill or fire (very rare) just about every 109 hit will be able to fly home or stick around for even longer fighting, not only is that utterly unrealistic it's imbalanced to the point of making the game (because that's what it is) a hopeless one sided deal!

at present if any of us get cooling damage we have the same chance of getting back, we have more chance of sustaining structural damage, you have more chance of sustaining cooling damage, it's about as fair and realistic as a game can get!

as we have said many times fly red, especially in the fragile (grossly unhistorical) Hurricane, then you will get the picture!

Kling
Apr-19-2013, 06:20
Nothing complicated about the 109 system, in fact it's very similar to the layout on most twin radiator single seat race cars, this is 1940 technology!


What you seem to be arguing for is the ability to take damage then be able to fly home, the real issue is don't get damaged if you get damaged get out of there if you can, last night alone I had one wing shot off and a tail removed, both by aircraft diving through the fight with a deflection burst, not a sustained burst but a quick shot , this happens regularly to red planes, yet we have to use large numbers of hits and hope for a pilot kill as 95% of the time even a sustained burst wont slow or degrade a 109's aerobatic capability, if your arguing for more time before engine failure (same for both sides) your going to create the situation where short of a pilot kill or fire (very rare) just about every 109 hit will be able to fly home or stick around for even longer fighting, not only is that utterly unrealistic it's imbalanced to the point of making the game (because that's what it is) a hopeless one sided deal!

at present if any of us get cooling damage we have the same chance of getting back, we have more chance of sustaining structural damage, you have more chance of sustaining cooling damage, it's about as fair and realistic as a game can get!

as we have said many times fly red, especially in the fragile (grossly unhistorical) Hurricane, then you will get the picture!

Im not arguing against you Gromit although it might look like it. I do regularely fly on the red side AND blue side and know perfectly well the issues with both sides. Both sides suffer from the issue where big holes in the wings dont create much drag or chage in performance. That is why i suggested the other day in another thread that, once we have taken hits in the wings or fuselages that the cockpit should start shaking in the same way as when the engine has been hit. Or something similar.


Now back to the overheat issue, Im sure there were a few cases back then where the engine would seize after 2min 10secs after a radiator leak but what I am saying is that it this really models a very big leak. It would be understandable if it radistor when from fully functional to empty in an instant
But we are talking about a leak here. Something leaking will give a slow and gradual rise in temp.
Same thing for the oil leak in game. Smae time limit 2mins 10secs. What about all the stories of pilots who flew home over the channel with leaking oil and managed to land at the lastlsecond. Currently in game we have no chnace of that.

And opposite from you I think that people stay and fight with leaking radiator because there is no chnace of getting home anyway. Not even the slightest.
I think that with a few mins longer to complete failure people would instead try to make it home because there is actually a chance of making it. We could have a slower leak instead of the fastest leak possible.

I think that would be more realistic and more fun

Im writing from my phone so sorry for all spelling mistakes

92 Sqn. Philstyle (QJ-P)
Apr-19-2013, 06:30
Both sides suffer from the issue where big holes in the wings dont create much drag or chage in performance.

Gotta disagree with you there.
I very recently made a video showing how a very limited amount of damage to one wing of spitfire has a dramatic impact on maneuverability. I wasn't going to post it online, but I think I will now.

The very small damage decal on one wing results in the following:
1. induced drag on that wing, casing the aircraft to roll - level flight is difficult to maintain without aileron input, which cannot be trimmed in the Spitfire so the pilot is constantly fighting this.
2. significant tendency to flick/spin in a turn when the damaged wing is on the low-side of the turn, making combat turns in that direction impossible. This is the main effect. It should put the pilot off continuing to fight, unless he's prepared to only turn in one direction. The 109 pilot who sees a spitfire damaged like this should turn in both directions to force the spit out of its performance envelope.

I suspect the 109 might also be susceptible to changed performance when the wings are similarly damaged. I need to get one damaged to the right amount so I can test it.

Kling
Apr-19-2013, 07:41
Gotta disagree with you there.
I very recently made a video showing how a very limited amount of damage to one wing of spitfire has a dramatic impact on maneuverability. I wasn't going to post it online, but I think I will now.

The very small damage decal on one wing results in the following:
1. induced drag on that wing, casing the aircraft to roll - level flight is difficult to maintain without aileron input, which cannot be trimmed in the Spitfire so the pilot is constantly fighting this.
2. significant tendency to flick/spin in a turn when the damaged wing is on the low-side of the turn, making combat turns in that direction impossible. This is the main effect. It should put the pilot off continuing to fight, unless he's prepared to only turn in one direction. The 109 pilot who sees a spitfire damaged like this should turn in both directions to force the spit out of its performance envelope.

I suspect the 109 might also be susceptible to changed performance when the wings are similarly damaged. I need to get one damaged to the right amount so I can test it.

Im sure youre right. But the other day I was fighting for a few mins without noticing that my spitfire had lost its right wingtip. The next day i had three big holes in the right wing although it was noticable in performance i still could fight.

Maybe its something in the code? Some damage casuses performance drag and some dont?!

Foul Ole Ron
Apr-19-2013, 07:54
Oh my goodness. If Clod had the overheat dynamics of the DCS P-51, many would quit on the spot. Hanging around near stall speed at full power is a big no no. :doh:

In the P51 make sure you manually open up the rads and coolant if you're planning on doing some aerobatic maneuvers while pushing the engine hard - especially up to stall speed. There's a marked difference in keeping the engine cooler with this approach. Auto works fine for normal tooling around but it's not efficient enough and can't keep up with some hard pushing. If you're on auto and have lowered MP during a dive and then you throttle it all the way back up for a zoom and lose speed the scoop isn't able to open up fast enough to compensate and temps will go into the red. Do this a few times and chances are you'll break something. They used true modelling of the radiator heatsink to calculate and calibrated with Mustang test results so I'd say it's pretty close to reality.

CLOD is pretty forgiving for the most part. I haven't busted an engine in quite a while except for that time I took off in a spit with the radiator fully closed. Took a Hurricane up to 28k the other day and temps barely went past 90C for most of the ride.

92 Sqn. Philstyle (QJ-P)
Apr-19-2013, 08:07
Im sure youre right. But the other day I was fighting for a few mins without noticing that my spitfire had lost its right wingtip. The next day i had three big holes in the right wing although it was noticable in performance i still could fight.


If you are missing a wing-tip you get better role rate in one direction. Not noticing it, and it not happening are two different things ;)

If you stop and thoroughly investigate the effects of each damage, you might be surprised.


http://www.youtube.com/watch?v=gNOA4ozu4cs
sorry for the engine sound being so loud, it's hard to hear my voice in the video..

Robo.
Apr-19-2013, 08:42
In the P51 make sure you manually open up the rads and coolant if you're planning on doing some aerobatic maneuvers while pushing the engine hard - especially up to stall speed. There's a marked difference in keeping the engine cooler with this approach. Auto works fine for normal tooling around but it's not efficient enough and can't keep up with some hard pushing. If you're on auto and have lowered MP during a dive and then you throttle it all the way back up for a zoom and lose speed the scoop isn't able to open up fast enough to compensate and temps will go into the red. Do this a few times and chances are you'll break something. They used true modelling of the radiator heatsink to calculate and calibrated with Mustang test results so I'd say it's pretty close to reality.

Very true, the automatics reacts very slow and it takes 20 seconds for the flap to open fully anyway. I prefer to flip both swithes to manual before I start the battery and generator to ensure they are in fully open position and I take it from there, helps a lot in dogfight situations. You're absolutely right of course...


CLOD is pretty forgiving for the most part. I haven't busted an engine in quite a while except for that time I took off in a spit with the radiator fully closed. Took a Hurricane up to 28k the other day and temps barely went past 90C for most of the ride.

Yes it is now, the overheating is now based on same logic like DCS or other sims (airspeed, engine management, radiator flow...) and is generally correct now. This was not the case in the stock version of the game, as you had some aircraft flying on WEP forever and some would overheat at certain altitudes for no reason at all. We don't have the complexity of a2a or DCS Mustang, but it's pretty good :thumbsup: The 2:10 seconds is simplified and models the coolant leak situation satisfactory imho - if you have enough altitude you might as well make it back home, otherwise you're doomed just like in real life (from what we can tell from reading the BoB pilot reports). At the Hurricane climb to 28k (again, something you would not be able to do pre-TF patch) the oil should be around 90, water around 100-105 when you fly it by the book, that is 6.25 @ 2700, radiator 50%, 160+mph IAS climb at 2000-2500fpm.

Robo.
Apr-19-2013, 08:47
Phil +1 to that video, that is exactly what I meant when I suggested to pilots complaining in this thread that they should grab a Spitfire or Hurricane and get shot at by 109s MGs and cannons :D. The effect is not visible from outside, but the plane will do just what you show in your video... This is also the case with 109 hit by MG fire, but to slightly less extent. The 109 wings are extremely prone to cannon damage, one or two Panzerbrandgranaten = half wing off.

Foul Ole Ron
Apr-19-2013, 12:40
We don't have the complexity of a2a or DCS Mustang, but it's pretty good :thumbsup:

Absolutely - it's vastly improved over the stock which had all sorts of oddness. Now we have defined thresholds that are pretty much more or less in-line with the way they were back then and we can push those thresholds by flying in a way designed to help the engine push them. I can imagine it was a nightmare to try and code all this correctly given how the stock code was bugged and (I'm guessing) maybe scripted in parts instead of modelled.


The 2:10 seconds is simplified and models the coolant leak situation satisfactory imho - if you have enough altitude you might as well make it back home, otherwise you're doomed just like in real life (from what we can tell from reading the BoB pilot reports).

It's a decent compromise for now given that it only takes a few minutes to get across the channel. I guess once TF take a look at the damage model we might see a few refinements though based on the size / number of the leak(s) involved. I could see a small leak certainly giving a bit more time than 2 minutes if the engine was husbanded quite a bit as opposed to continuing to fly with full combat power. Having kills only being recorded as kills if the gun cam makes back to friendly territory might help people treat coolant leak a little more than a 2 minute kill timer but I'd be afraid that this might penalise blue pilots (or more offensive pilots in general) as they have less chance to make it back.

VO101_Kurfurst
Apr-22-2013, 14:57
The spitfire radiator system is pressurized and therefor boils at a higher temperature and if memory serves me well, it was also a mix of water and coolant. Where as the german planes had unpressurized radiator system and their radiator system should boil at a lower and lower temperature the higher the plane goes. The boiling point of water for example at 7000m is 77 degrees Celcius. This is however not modeled in the game and the boiling point for axis planes in game is always 100 degrees Celcius. I think this is the main reason the 109 has two big radiators where as the spit only has one.

The 109 coolant system WAS pressurized and was using a mix of glycol and water (50-50). Early Spitfire used only glycol, which has higher boiling point but less capacity to transfer heat. I am not sure you can compare German limits to British limits straight - from what I have seen the Germans have usually two limits, one (lower) temperature can be maintained indefinitely, the other only for shorter (10 mins) periods.

The current near instant destruction of the engine/exploding/leakage of the radiators is gamey IMHO. IRL the pressure valves would release steam and pressure, and after a long while, you would probably loose enough coolant to endanger the engines cooling but it would take some time.


I read somewhere that the germans were jealous when they saw a captured Spitfire and the efficiancy of its coolant system.

Uhm, there was a DB tests that compared the single, rather large(r) copper radiator of the Mark V Spitfire to the twin aluminium coolant radiator of the 109G (Emil however had copper, too, copper is heavier, more expansive and maybe more difficult to weld, and certainly less available in Germany but has better heat transfer) and they found it to have iirc 97% of the capacity of the twin 109G system, which they indeed found impressive. However iirc the Spitfire single radiator was also heavier... its a complex question, weighting weight, drag and heat transfer, circulation speed etc.

Kling
Apr-22-2013, 18:26
The 109 coolant system WAS pressurized and was using a mix of glycol and water (50-50). Early Spitfire used only glycol, which has higher boiling point but less capacity to transfer heat. I am not sure you can compare German limits to British limits straight - from what I have seen the Germans have usually two limits, one (lower) temperature can be maintained indefinitely, the other only for shorter (10 mins) periods.

The current near instant destruction of the engine/exploding/leakage of the radiators is gamey IMHO. IRL the pressure valves would release steam and pressure, and after a long while, you would probably loose enough coolant to endanger the engines cooling but it would take some time.



Uhm, there was a DB tests that compared the single, rather large(r) copper radiator of the Mark V Spitfire to the twin aluminium coolant radiator of the 109G (Emil however had copper, too, copper is heavier, more expansive and maybe more difficult to weld, and certainly less available in Germany but has better heat transfer) and they found it to have iirc 97% of the capacity of the twin 109G system, which they indeed found impressive. However iirc the Spitfire single radiator was also heavier... its a complex question, weighting weight, drag and heat transfer, circulation speed etc.


Tyx bud!
You should pop in more often Kurfurst! :)

Robo.
Apr-23-2013, 08:01
The 109 coolant system WAS pressurized...

Only partially so... The temp limits for Bf 109E are getting lower with atlitude rising, which would not be the case with fully pressurised system (eg Merlin XII).

VO101_Kurfurst
Apr-23-2013, 11:59
Either something is pressurized or it isn't IMHO.. besides I am not quite certain that it was about the temperature of the coolant, but more so the temperature of the engine parts, just like on radials, that made those limits. The gauge measured exit/inlet coolant temperatures, not that of the engine parts, though the coolant temp may well have been an indication of how hot the engine actually ran.

I am not an engineer but it would seem logical to me, that there is considerable difference between how hot an engine actually runs between an engine letting out 100 celsius coolant at 20 celsius outside temperature (i.e. Sea Level) and another doing the same at -40 celsius temperature (i.e. at 9000 meter). Even liquid cooled engines are cooled by external air temperature (they do take in a lot of cold air, for example).

The Merlin's single temp limit may well be a simplification for the pilots (a kind of an avarage value, like early dive limits set in stone around 420 mph IAS. Obviously that would be waaaay too optimistic at high altitudes). Its easier to rememeber a single value. All guesswork of course, but I do not buy either the Merlin wonder-coolant agent or wonder-pressurarization story.

92 Sqn. Philstyle (QJ-P)
Apr-23-2013, 12:46
E
I am not an engineer but it would seem logical to me, that there is considerable difference between how hot an engine actually runs between an engine letting out 100 celsius coolant at 20 celsius outside temperature (i.e. Sea Level) and another doing the same at -40 celsius temperature (i.e. at 9000 meter). Even liquid cooled engines are cooled by external air temperature (they do take in a lot of cold air, for example).
.

Not forgetting of course that;

1 - high altitudes the mixture is leaner, thus reducing the fuel-cooling effect.
2 - at higher altitudes the thinner air is not as good at conducting heat (convective heat transfer away from the engine), thus the engine has to work harder to force the same amount of cooling air into the radiator. The closer you get to space, the more you rely on Thermal Radiation to do this work - eventually the air intake (convective system) becomes useless (I think?).

The best way to test the impact of OAT alone would be to do it at the same or similar air pressure, thus at sea level on hot and cold days - and not at different altitudes.

Robo.
Apr-23-2013, 13:43
Either something is pressurized or it isn't IMHO.. besides I am not quite certain that it was about the temperature of the coolant, but more so the temperature of the engine parts, just like on radials, that made those limits. The gauge measured exit/inlet coolant temperatures, not that of the engine parts, though the coolant temp may well have been an indication of how hot the engine actually ran.

I am not an engineer but it would seem logical to me, that there is considerable difference between how hot an engine actually runs between an engine letting out 100 celsius coolant at 20 celsius outside temperature (i.e. Sea Level) and another doing the same at -40 celsius temperature (i.e. at 9000 meter). Even liquid cooled engines are cooled by external air temperature (they do take in a lot of cold air, for example).

The Merlin's single temp limit may well be a simplification for the pilots (a kind of an avarage value, like early dive limits set in stone around 420 mph IAS. Obviously that would be waaaay too optimistic at high altitudes). Its easier to rememeber a single value. All guesswork of course, but I do not buy either the Merlin wonder-coolant agent or wonder-pressurarization story.

With all due respect you're not entirely right in here, the OAT was a factor of course, but more so it was the density of the air and therefore air mass flow through the radiator. Believe ot or not the British did have a bit more efficient cooling system than the Germans at this time and the Merlin XII (Spitfire Mk.IIa) was the most sophisticated fighter of all modeled in this game in this particular aspect. Hence the higher tolerance of this engine and higher temp limit at all altitudes. I'd say the a2a Spitfire for FSX models this in great detail and provides a fascinating insight into how the early Spitfires worked, more than CloD. CloD with TF is stil very very good in general and the FMs reflect the differences between Mark 1 and Mark 2 Spit at least, with the latter having higher water temp limit due to further technical improvements.

I am completely with you regarding the pressure release valves :thumbsup:

Gromit
Apr-23-2013, 13:59
You also need to take cylinder filling into account when you look at temps, at high altitude the lower air density makes life quite hard for the supercharger to fill the cylinder to it's required boost level, which is why power outputs drop as altitude above FTH increases, the less charge pressure you have, the lower the power output, and the lower the power output the lower the generated engine temp!

VO101_Kurfurst
Apr-23-2013, 17:12
With all due respect you're not entirely right in here, the OAT was a factor of course, but more so it was the density of the air and therefore air mass flow through the radiator.

Of course...



Believe ot or not the British did have a bit more efficient cooling system than the Germans at this time and the Merlin XII (Spitfire Mk.IIa) was the most sophisticated fighter of all modeled in this game in this particular aspect.

What I fail to see is why would be so sophisticated?

Use of copper rads? Same thing on the 109E.

Different sized radiators, different cooling surface? Perhaps. Exact size of the radiators would be need to be known to be sure, and even the number of them will not give you a perfect answer.

Use of pressurized coolant agent? Same thing on the 109 (+ 0.75 atm pressure, closed system). People talk about pressurized cooling a lot, but its a bit like saying the Merlin XII ran on gas, a supposedly very sophisticated feature for the era. :D

Use of glykol in the coolant agent? Same thing on the 109, the difference is that Merlin XII used 30% glycol, the 109 50% glycol (and french sources claim 100% water in the summer as anti freeze was not needed, this could be an "also can be used in emergency" IMHO. Now glycol has higher boiling point (197 celsius) but only about half the heat transfer capacity of water.

Depending on the ratio of a higher water content (provided that there is the same volume of water in both engines - doubtful, and given two radiator housings and a larger block, my bet would be on the 109) the higher water content may lead to better heat transfer BUT this assumes a) same or better circulation rate b) same or larger total coolant volume. HOWEVER if the Spitfire II had better cooling capacity - this would also likely mean that the coolant temperature limits would be LOWER (which is not the case, the reasons see below)

Faster coolant circulation? Maybe yes, maybe no, in fact its completely unknown (for the Mark II. Known for 109).


Hence the higher tolerance of this engine and higher temp limit at all altitudes.

Again the temp limit of coolant is only an indicator of engine temperature. In itself, coolant temperature is meaningless, since there is an equatation between coolant temperature and engine temperature, and its different in all engines. A 100 celcius coolant may indicate that the engine parts running at 400 celsius in one engine, and 300 celsius in another.

Coolant temperatures only indicate wheter the radiator system can or cannot cope with the heat generated by the engine - thats simple enough. High coolant temp - the engine generates more heat than the radiator can transfer to the air and cool down the coolant in time, and vica verse. Given that there is a balance between coolant temperature and engine temperature (since coolant transfers a roughly fixed amount of heat), the rise of coolant temperature indicates a rise of engine temperature. thats simple enough, too.

However, that balance, ie. what is the highest coolant temperature at which engine parts are still operating at tolerable temperatures, ie. the critical point is unique to each engine.

It may be that:

- an engine is running at acceptable temperatures (no damage to parts), but the coolant system is undersized cannot cope with it entirely and cannot cool down the coolant sufficiently, hence very high coolant temperatures observed, but the engine is still at safe temperatures. I.e. it simply follows from that balance that 130 celsius observed in the coolant systems means 300 celsius for the engine parts, ie. within the safe limit.

- the engine is running at unacceptable temperatures (danger of damage to parts), but the coolant system is oversized and can cope with it entirely and cool down the coolant sufficiently, however the engine is running above safe temperatures.

In an extreme case with vastly oversized cooling system with enough water that would fill half the Nile and the coolant running at 80 celsius you can still have an engine that is melting down before it can boil all that water if that water circulates with the same extremely tedious pace as the Nile, because then it simply cannot transfer heat away from the engine fast enough.


I'd say the a2a Spitfire for FSX models this in great detail and provides a fascinating insight into how the early Spitfires worked, more than CloD. CloD with TF is stil very very good in general and the FMs reflect the differences between Mark 1 and Mark 2 Spit at least, with the latter having higher water temp limit due to further technical improvements.

Well that technical improvement may be just that they were using twice as much good old H2O (with twice the heat transfer capacity) than previously. ;) Simply to put, coolant of 2/3s water running as high as 130 celsius could still well mean the Merlin's delicate parts were running cool enough.

Certainly I agree that the increased cooling effectiveness of the Spitfire II vs Spitfire I should be very noticable because of the use of much increased amount of water as a cooling agent, the thing I was pointing out that there was nothing particularly 'sophisticated' about that. Everyone used water and everyone pressurized their coolant systems. The fact that DB engines had lower coolant temperature limits specificed for safe engine limits probably just indicates that the cooling system was very effective, and by the time the coolant reached 100 celsius despite that, it meant that the engine itself was running very hot, probably hotter than a Merlin in a Spitfire when the needle crept up to the same 100 celsius there.

p.s. btw I just started reading up on the subject of ideal coolant temperature, well.... lets just say its a massively more complex subject, effecting virtually anything, but long story short - there is no simply answer or "best" coolant temperature. Its all tuned carefully for the particular engine.

Robo.
Apr-24-2013, 16:45
p.s. btw I just started reading up on the subject of ideal coolant temperature, well.... lets just say its a massively more complex subject, effecting virtually anything, but long story short - there is no simply answer or "best" coolant temperature. Its all tuned carefully for the particular engine.

To learn more about the system used in Merlin XII you can read more about the early Merlin developement (Kestrel, Goshawk and some other early evaporative / condenser cooling systems). Everything that RR used for the above improvements has been learned back then in that era. :thumbsup:

VO101_Kurfurst
Apr-24-2013, 18:33
Any reading recommedations, Robo-sama? :)