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fordfan25
02-28-2006, 12:05 PM
why does the p-51D over heat so much faster than the spit ? iv just noticed that in online DF servers i never OH when flyn the spitty.

gkll
02-28-2006, 12:25 PM
Others know much more than me about this... however a couple of brief points may be relevant.

- Spit has large and draggy rads. Rad size was upgraded from the V to the IX (although only one side is actually rad on later spits. P51 under certain rad settings had lowest drag rad of all.....

- nothing for free? Spit has draggy large rad and is quite resistant to overheat. Also slower than P51 which is heavier and larger with the same motor. So maybe spit designers simply accepted compromise (high drag) in favor of good cooling...? Remember all motors can be cooled under full power settings, when they don't it is (usually) a design choice. Well, aircooled may be a touch different... however for liquid cooled you can always cool them if you want to.

Zoom2136
02-28-2006, 12:38 PM
Maybe you get shotdown to fast http://forums.ubi.com/images/smilies/35.gif

luftluuver
02-28-2006, 12:52 PM
Also slower than P51 which is heavier and larger with the same motor. nit pickin gkll.

Yup, the P-51 had a 2" greater wing span. Length was 14" greater. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif


although only one side is actually rad on later spits
Both rad positions on the later Spits held an engine coolant rad. On one side was also the intercooler while the other side had the oil cooler.

Xiolablu3
02-28-2006, 03:22 PM
Spitfire only revs to 100% whereas other planes over rev to 110%.

Surely this makes some difference?

It does overheat, just not as fast as other planes. I have knackered the engine on a Spitfire many times from overheating.

Grey_Mouser67
02-28-2006, 05:48 PM
How about this...the Mustang is modelled wrong! Probably several other planes too...the Mustang did not suffer from overheat even at boost levels in real life.

Crop-Duster.
02-28-2006, 07:55 PM
How about this?

Just get Oleg to remove the Mustang next patch.

Whining problem solved..

gkll
02-28-2006, 11:21 PM
Luftluuver said:
Both rad positions on the later Spits held an engine coolant rad. On one side was also the intercooler while the other side had the oil cooler

Thanks for this. I assumed rads both sides and got corrected a year or so ago, this makes more sense.

And Greymouser there is a distinct possibility that many planes are off... but?

It is a fact that you can cool any motor if you want to. Look at that crazy Blohm and Voss high altitude 109 mod. BV155? Anyways the thing has absolutely enormous rads, at 52,000 feet you can't get enough air to cool..... point is this plane is an extreme case of a ship compromised to ensure proper cooling. So you can always do this, for any set of flight conditions. Leads me to think that either Oleg is wrong, or, a lot of designers intentionally underdesigned the cooling systems to get better aero and top end.

Some here might know about design philosophies of the various teams that designed the planes we are using.... what was the deal on cooling vs drag?

SnapdLikeAMutha
03-01-2006, 05:03 AM
Originally posted by Crop-Duster.:
How about this?

Just get Oleg to remove the Mustang next patch.

Whining problem solved..

http://forums.ubi.com/images/smilies/agreepost.gif

fordfan25
03-01-2006, 11:47 AM
Originally posted by Crop-Duster.:
How about this?

Just get Oleg to remove the Mustang next patch.

Whining problem solved.. then wed lose the 109 and FW as well http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

Viper2005_
03-01-2006, 01:08 PM
Cooling in this game is bugged. For a start there isn't even a cooling system modelled; the game just uses oil temperature. This makes most liquid cooled fighters far too resistant to damage.

I think it's just a gameplay thing to stop people from using WEP all the time, without punishing them too hard. You get an overheat warning. You then close the throttle, open the radiators and everything's fine.

The Spitfire is a "special case" in this regard. The Mk IX has an automatic radiator system without manual override. This poses some serious problems, as this means that it must hit its book TAS with an open radiator...

Really strange things happen if you run a Spitfire flat out in game. You'll overheat if you fly to fast, and you'll magically cool down if you pull some "g"!

In this respect the Spitfire is pretty unique. It makes it an especially deadly fighter.

You can also climb from the deck to high altitude in WEP without overheat; in this respect it is one of the few fighters in the game to be realistic; this makes it look artificially good when compared with all the other fighters in the game:

IRL you'd be unlikely to overheat even in the Summer in Northern Europe, unless you got slow for an extended period of time; the Spitfire could climb to 30,000 feet using WEP (+25) without overheat (of course above the +25 FTH boost would fall off...).

Instead, excessive WEP use would be signified by a loud bang, a windscreen covered in oil and rather expensive bits of engine poking through the cowling.

This kind of behaviour is far from user-friendly.

The concerning thing about it is that it would happen randomly. IRL some engines were tested for upwards of 100 hours in WEP conditions (mostly +18, though considerable running time was amassed at higher ratings). But sometimes they'd fail after a few hours or even a few minutes, because what generally happened during such runs is that the engine would be run until something broke; that would be repaired and then the engine would be run until something else broke.

In operational service, the same sort of thing would apply. Engine overhaul lives were under 300 hours for most of the war, and only a percentage of engines lasted even that long.

If you happened to fly an aeroplane with a "tired" engine then you might well find that sticking to the handbook limits was a good idea.

If you were given a brand new aeroplane then you could probably take some liberties with the operating limits.

Since we have no context most of the time (especially online), the best way to model this would be a random total WEP useage time to failure. There would be no "recovery" as at present, just a timer. You might get into the aircraft and have an hour of WEP; you might only have 10 minutes.

The timer would tick whenever the engine was operated outside of limits; the rate at which it ticks would be a function of the power used.

So if you use WEP then it might tick in realtime.

If you use climb power then it would tick a bit slower.

As power tends towards max continuous, so the timer's speed would tend towards zero (though a bit of random chance might be added to this; sometimes engines fail despite having been operated within limits!).

This sort of thing would probably not be popular with many pilots. For a start, you'd have to actually observe the limits in the Pilot's Notes, which are often quite restrictive. And the random nature of the failures would probably drive some to distraction; afterall it's all about talent and skill, not luck, right?

Personally I'm all in favour of realism, but I think that a lot of people wouldn't like the reality of flying aeroplanes*...

Getting back to overheating, I think that it is worth pointing out that if this game is to be believed, nobody during WWII was capable of designing a radiator which could satisfy the cooling requirements of the engine of a WWII fighter.

This is clearly nonsense. Over at Spitfire performance there are a lot of very instructive graphs and tables which serve to show you just how little radiator opening was actually needed to keep most Allied fighters cool during operational flying.

Radiators were actually designed around the worst design condition. This was often climb, but in some cases was associated with ground running requirements (power checks for example).

British fighters were generally designed on the basis of the assumption that they might be called upon to defend any part of the Empire, lots of which is/was quite hot; certainly ISA +15ºC at least.

American fighters had to put up with the American climate before going off to fight a war. Again, ISA +15ºC at least in the Summer; +20 is probably nearer to the mark.

As such in the European context most of the Allied fighters in the game should have no problem at all.

There is no reason to think that the German fighters were any different.

At the end of the day, the guys designing these aircraft weren't stupid. They could do their heat transfer sums. It's not that hard to size a radiator.

The only time we should see overheating become an issue is ground running (operating at idle on the ground for more than 5 minutes or so isn't a good idea!).

A special case is aircraft fitted with wing mounted radiators (eg Bf-109 and Spitfire) which should experience trouble in the circuit due to the landing gear legs disrupting flow into the radiators.

But once you're gear up and flying there should be very little need to worry about overheating, provided that the designer was capable of carrying out some pretty basic arithmetic. Designing radiators is rather simpler than designing aeroplanes...

It's harder to make air-cooled engines behave because the radiator size is a function of cylinder area. The bigger your cylinders the harder it gets; but the smaller the cylinders the less thermally efficient they are (apart from those increased heat losses you also lose more to friction, flame travel distances are larger etc.).

Fan cooling, as pioneered on the Fw-190 is a very neat solution, but there are limits to how much you can get away with, and the back row will always run hotter than the front row whatever you do...

Cooling was the primary factor limiting the development potential of the R-2800; getting more horsepower out of it wasn't a problem - stopping it from melting was.

Of course you can "cheat" with an "air cooled" engine by dumping more heat into the oil (the oil system has to have a radiator anyway), but there are limits to this approach. Water is a better coolant than oil afterall!

Liquid cooled engines get around this by simply using a bigger radiator and more powerful cooling pumps; in the final analysis they tend to be knock limited.

On the other hand you've got more technical complexity to worry about.

Anyway the long and the short of it is that overheat should be the least of our worries.

Cyrano
03-01-2006, 02:01 PM
Originally posted by Crop-Duster.:
How about this?

Just get Oleg to remove the Mustang next patch.

Whining problem solved..


No need, players are already "voting with their feet". Look at the ratio of Spits to Mustangs on most servers.
The great disapearing act continues http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Abbuzze
03-01-2006, 05:09 PM
No need to worry, you just discovered that the spit is the maybe least overheating plane in this sim...
You should feel lucky, you have a properly modelled overheat in your P51 http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Grey_Mouser67
03-01-2006, 06:28 PM
I don't know if the Spit is acurrately modelled in terms of overheat, but it is slower than all of its contemporary enemies at most altitudes...only the Mk IX is close to the 109G at sea level and again faster above 21,000 ft or so...all fw's put it to shame, early and late 109's put it to shame...radiator or not, if you are having trouble fighting spits, it is not due to speed, but rather angles fighting likely.

I fly with and against Spits and I find that I have great success with and against Spits...probably more so than any other planes I fly.

This conversation is kinda like combat flaps...it is hard to have a discussion about the overheat modelling of one aircraft without talking about the global modelling or that of so many other aircraft...heck the P&W radials don't even have working cooling flaps! Yes they open and slow your plane down, but they don't cool!!!! Lets get that one fixed first please!

Jetbuff
03-01-2006, 07:18 PM
Are you comparing the Mustang with radiator set to Auto? The spits from the MkIX onwards automaticall control the radiator and there is no override.

HellToupee
03-01-2006, 08:35 PM
Originally posted by Grey_Mouser67:
I don't know if the Spit is acurrately modelled in terms of overheat, but it is slower than all of its contemporary enemies at most altitudes...only the Mk IX is close to the 109G at sea level and again faster above 21,000 ft or so...all fw's put it to shame, early and late 109's put it to shame...radiator or not, if you are having trouble fighting spits, it is not due to speed, but rather angles fighting likely.


That would be ebcause late 109s etc arnt contemporay unless 25lbs, speed wise it should be faster than contemporay 109s and equal contemporary 190s in speed at certian heights.

Cooling wise spit has some of the biggest rads in the game which operate on auto and never more than half close. But dosnt explain the weird ness of how overheat works.

gkll
03-01-2006, 09:26 PM
Nice post Viper. I appreciate the chance to learn more, my info is extensive but rarely detailed, much comes from personal experience as a gear head....

fordfan25
03-01-2006, 09:28 PM
Originally posted by Jetbuff:
Are you comparing the Mustang with radiator set to Auto? The spits from the MkIX onwards automaticall control the radiator and there is no override. stang on auto or open eather one will OH WAY faster than spit in fact all the planes i normaly fly will german and USA. i can set wep on in the spit and wide open power and it takes forever and a day to OH in fact i have yet to have it OH in 334th......not that i fly in 334th.......not that im saying anything is wrong with that.......STFU http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif .

BfHeFwMe
03-01-2006, 11:07 PM
Something I've never understood is the complete lack of cooling bank. Altitude and it's cooling extremes requires a low temp thermostat on the radiator exit lines for both coolant and oil, does today, did back than. As long as you don't exceed that minimum temp the fluid will drop to that thermostatic set temp if the rads are wide open at altitude. The low side thermostat shuts the line to prevent the engine block from failure due to overcooling and cracking the heads or worse.

The system is there as a backup if the main rad shutter actuator should fail, not as a primary control. But it does allow the pilot to regulate temp with the ability to bank cooling when it's cool enough to autoclose the main rad actuators.

This game acts as if the temp is chronically hot for all conditions, you can't cool it below your normal operating parameters even if you try. That don't jive with what's out in the world. In game when's the last time you saw the rads fully close on auto, even half?

It's easy to drop oil temps 20 C on a decent into a hot airport from altitude simply by opening the oil flaps a few minutes before dropping. Sometimes procedures demand it, such as trash haulers doing engine running off loads of beans and bullets in a scorching desert environment. No way they could sit there for ten minutes and unload with normal temps upon landing.

blackpulpit1970
03-02-2006, 08:02 AM
Try this on the new spit, use %85 power which is the same as full power and you will never overheat...BUG. 85% POWER IS THE SAME POWER OF 100% ON THE NEW SPIT.