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View Full Version : Do radiators cool the engines on any planes?



XyZspineZyX
08-13-2003, 08:27 AM
I had sort of noticed this in the unpatched version, but was waiting for patch to do any real testing, and for all I know it is working as intended, but it certainly isn't working the way I would expect it to (my experience is with automotive engines, so maybe I am missing something). The thing is that opening the radiator does not seem to be increasing the cooling capacity, in that it does not allow higher power settings to be maintained without overheating.

I tested the FW190D-9 1944 and the Bf109K-4 on the Crimea map with CEM on and wind/turbulence off, flying below 300m. The 190 could maintain throttle setting 95% and not overheat. At throttle setting 96% it overheats. What strikes me as odd is that this is true even if the radiator is fully open. With the 109 it will run forever at 82% throttle, but overheat at 83%, once again regardless of radiator position. This does not seem right, and I wonder if is true of all planes, or just some. If it is true of all, then is there some universal radiator bug, or is this intended and its effects are modelled in some other way(s)?

Previous testing that I did prepatch indicated that the maximum throttle setting without overheat is affected by altitude, airspeed, and ambient temperature as well (in the form of which map is used), so it seems there should be some mechanism by which radiator setting affects this as well. It also raises the question as to what, exactly, does opening the radiator do, other than slow the plane down.

XyZspineZyX
08-13-2003, 08:27 AM
I had sort of noticed this in the unpatched version, but was waiting for patch to do any real testing, and for all I know it is working as intended, but it certainly isn't working the way I would expect it to (my experience is with automotive engines, so maybe I am missing something). The thing is that opening the radiator does not seem to be increasing the cooling capacity, in that it does not allow higher power settings to be maintained without overheating.

I tested the FW190D-9 1944 and the Bf109K-4 on the Crimea map with CEM on and wind/turbulence off, flying below 300m. The 190 could maintain throttle setting 95% and not overheat. At throttle setting 96% it overheats. What strikes me as odd is that this is true even if the radiator is fully open. With the 109 it will run forever at 82% throttle, but overheat at 83%, once again regardless of radiator position. This does not seem right, and I wonder if is true of all planes, or just some. If it is true of all, then is there some universal radiator bug, or is this intended and its effects are modelled in some other way(s)?

Previous testing that I did prepatch indicated that the maximum throttle setting without overheat is affected by altitude, airspeed, and ambient temperature as well (in the form of which map is used), so it seems there should be some mechanism by which radiator setting affects this as well. It also raises the question as to what, exactly, does opening the radiator do, other than slow the plane down.

XyZspineZyX
08-13-2003, 10:01 AM
I also recognized this.

quiet_man

second foundation member of the EURO_Snoopy fan club!

I'm quiet_man, but if I post I post quiet much /i/smilies/16x16_smiley-happy.gif

XyZspineZyX
08-13-2003, 01:58 PM
It works, at least on any of the planes I've flown. Ever since I started making use of the radiator I rarely ever see an overheat warning.

Just like in a real plane, running the engine hard may eventually overheat it. Opening the radiator just delays it somewhat. For example, if I don't touch the radiator in the P39 I can fight for a couple of minutes before it begins to overheat.

If I open it up before I go into combat I never overheat. If I were to run the engine at 100%+ in straight and level flight for extended periods of time it'd overheat even with the radiator open, but so long as you're careful about engine management it's not an issue.

Only use high power settings when you really need them, like when closing head on with an enemy, there's no reason (or point) to running it up to 110% as soon as you spot them at 5km out. Wait until the distance closes to maybe 1.5 - 2km.

Pull the throttle back when you point the nose down, I also tend to do the same at the top of a loop as well. Unless you're running from someone immediately on your tail, or trying to catch someone who's just out of range, throttle back to 75-80%. You'll still get most of your speed that way, you'll burn less gas, and you'll definitely take better care of your engine.

You don't need to avoid high power settings to keep from overheating, just don't stay at a high setting for a second longer than you have to.

As for CEM, if you're overheating, you're probably doing something wrong. Try enriching the mixture a bit, and use higher power settings as little as possible. Settings that produce the most power can also create the highest temps.

XyZspineZyX
08-14-2003, 01:50 AM
OK, I just tested the P39N-1 under the same conditions I tested the FW190D-9 '45 and the Bf109K-4. In the P39 the radiator is clearly working to cool the engine, it is quite noticeable.

At below 200m it will run forever at 101% throttle without overheating and with radiator closed. With the radiator open it will run at 104% throttle without overheating. Furthermore, opening the radiator causes the engine temperature to rise more slowly (when throttle is set higher than the limit) and decrease more rapidly (when throttle is set lower than the limit). All in all it behaves exactly as I would expect (I have had well above average education when it comes to chemistry, and I still remember much of it).

There seems to be some planes (2 that I know) that have radiators that are not functioning properly. So everyone pick your favourite plane(s) and do some tests to see if different radiator settings have any effect.

step 1: Determine maximum sustainable throttle setting without overheating near sea level on the Crimea map with radiator closed (this may take awhile). Once this number is found allow the plane to run at this setting for awhile to stabilize heat/temperature.

step 2: go 1% throttle higher than this and note how quickly the overheat message appears.

step 3: Open the radiator and see if the overheat message stays.

step 4: Determine the maximim throttle setting without overheating with the radiator open (if the overheat message did not go away in step 3 then this will be the same number as in step 1).

step 5: Get to the throttle setting found in step 1 and make sure you do not have the overheat message on, but that your engine is hot (i.e. as hot as it will get at that throttle setting).

step 6: Open the radiator, then set throttle 1% higher than the setting found in step 4. Note how long it takes before the overheat message appears.

step 7: Allow the overheat message obtained in step 6 to remain for 10 seconds, then throttle back to 1% lower than the setting found in step 1 and note how long it takes for the overheat message to go away.

steps 8-10: Repeat steps 5-6, but keeping the radiator closed the whole time.

XyZspineZyX
08-14-2003, 02:14 AM
For me, the radiator has always seemed to have a noticeable effect. I am flying the Leningrad '41 campaign in an LaGG-3. With radiator always at position 6, the engine never overheats as long as I don't keep it in overdrive. Sometimes after a high-throttle fight I'll open it all the way up, and it does facilitate cooling.

***************************************

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"...I possess the wings of faith. Though heavy on my shoulder (no measurement can prove their weight), still a burden are they not to me. I am the challenger of gravity." ---Emperor

XyZspineZyX
08-14-2003, 02:27 AM
I feel the FW190A and P40 series works reasonably correct (though I don't have figures as you do), with open radiator the temperature guage runs considerably (10-20deg) cooler.

But as to your statement Fillmore, the two aircraft you mention both have (had?) 'automatic' radiator settings, possibly this is effecting your tests? Or that is where a 'bug' lies? From the above and my own experience it appears that the non-automatic type radiators are working correctly. I have no experience with the auto radiators.

XyZspineZyX
08-14-2003, 03:01 AM
On the FW and Bf I tested I tried every radiator position, including auto, and none of them seemed to work.

I wanted to edit my post to add comments and refine the proposed procedures, but it gave me errors so I will post here the edited version. I will be doing more extensive testing in the future and may come up with a better procedure.

OK, I just tested the P39N-1 under the same conditions I tested the FW190D-9 '45 and the Bf109K-4. In the P39 the radiator is clearly working to cool the engine, it is quite noticeable.

At below 200m it will run forever at 101% throttle without overheating and with radiator closed. With the radiator open it will run at 104% throttle without overheating. Furthermore, opening the radiator causes the engine temperature to rise more slowly (when throttle is set higher than the limit) and decrease more rapidly (when throttle is set lower than the limit). All in all it behaves exactly as I would expect (I have had well above average education when it comes to chemistry, and I still remember much of it).

There seems to be some planes (2 that I know) that have radiators that are not functioning properly. So everyone pick your favourite plane(s) and do some tests to see if different radiator settings have any effect.

step 1: Determine maximum sustainable throttle setting without overheating near sea level on the Crimea map with radiator closed (this may take awhile). Once this number is found allow the plane to run at this setting for awhile to stabilize heat/temperature.

step 2: Determine the maximum throttle setting without overheating with the radiator open.

step 3: If the throttle settings found in steps 1 and 2 are the same, then set throttle there and let it get as hot as it will at that setting with the radiator closed. Then move throttle 1% higher and note how quickly the overheat message appears. Now set the throttle back to the number found in steps 1/2 (remember you are only doing this if both those numbers are the same) and open the radiator. Allow the engine temp to stabilize (at least 5 minutes, 10 would be better). Now move the throttle up 1% and see if it takes any longer to get the overheat message than it did when starting with radiator closed.

step 4: Get to the throttle setting found in step 1 and make sure you do not have the overheat message on, but that your engine is hot (i.e. as hot as it will get at that throttle setting).

step 5: Open the radiator, then set throttle 1% higher than the setting found in step 2. Note how long it takes before the overheat message appears.

step 6: Allow the overheat message obtained in step 5 to remain for 10 seconds, then throttle back to 1% lower than the setting found in step 1 and note how long it takes for the overheat message to go away.

steps 7-9: Repeat steps 5-6, but keeping the radiator closed the whole time.

If steps 1 and 2 give different numbers, then the radiator is clearly working and the rest is just to quantify how well it works. If steps 1 and 2 give the same number then step 3 is used as an attempt to find some quantifiable difference between radiator closed and open before going on. The rest is designed to quantify how well the radiator is dissipating heat open vs closed.

The way the cooling system should work is dependant upon several factors:

A) the heat capacity of the coolant (this is purely a matter of the mass and composition of the coolant/oil/engine used)

B) the rate at which heat is generated (this is a function of the engine, the more power it generates the more heat, less power less heat. Note that the relationship is not linear). This should be affected by throttle setting, manifold pressure, engine RPM.

C) the rate at which heat is dissipated (this is a function of heat transfer between the coolant/oil/engine and the outside air). This should be affected by ambient temperature, pressure, humidity and radiator position.

Step 1, above, is designed to find out at what throttle setting B and C are equal with the radiator closed. Step 2 finds where B and C are equal with the radiator open. If steps 1 and 2 give the same number (as is the case with 109K-4 and FW190D-9 '45) then it means that the 1% increase in throttle is increasing B as much as opening the radiator increases C. Or that the radiator is bugged and opening it does not increase C.

XyZspineZyX
08-14-2003, 03:20 AM
Aren't you forgetting something?

There's a whopping drag penalty throwning some of those cowls and flap open. Don't you notice your airspeed drop due to this?

Full open is really a ground use only in most aircraft, they tend to heat up rather fast with little air flow on taxi. Most of these planes run much faster with rads closed and throttle slightly reduced with little chance of overheat. No trouble fighting a 109 all day with the rad fully closed, only a nut is going to run it wide open running high speeds. Your only adding more heat by over working the engine with higher drag when you open them wide. Open only when your slowing or on the dive part of manouver, or just crack it to position 2 and ease off the WEP, you'll get far superior speeds.

P-39's got a small scoop, not much differance open or closed, it shows on the airspeed.

XyZspineZyX
08-14-2003, 04:04 AM
I think it is that all planes with an auto setting on the radiator are bugged so that radiator setting has no effect on cooling. I just tried a Bf109E-4 (which I thought didn't have an auto setting, but it does) and it is the same. With 93% throttle it won't overheat, switch to 94% and it will, open the radiator and it has no effect on temperature.

yes I am aware that airspeed makes a diference in cooling rate (as I mentioned in my post), and in fact the 109E-4 can only maintain 92% throttle with the radiator open due to the lower speed, but if you are already at a high speed opening the radiator should increase the cooling (rate at which heat is dissipated) and it doesn't in some planes. You should be able to cool your engine more quickly by opening the radiator and throttleing back rather than by just throttling back.

I am also aware that many planes were designed to fly with radiator closed and opening it was just for taxiing on the ground (I recall a notice in the P47 cockpit warning against opening the cowl flaps at above a certain speed).

But I don't think that they would go to all the trouble to incorporate automatic thermostatically controlled radiator flaps if it was only ever to be used on the ground. I would expect that at cruising speeds one would fly with the raditor in auto mode to keep the engine cooler than would be the case at a lower throttle/same speed/radiator closed configuration.