How to prevent over-cooling?

I've run into a problem of engine failure while RTB on mission 2 of the Big Show campaign, and I suspect it's due to over-cooling of the engine.

I'm less than 10 minutes out from Ford on my way home cruising 220mph at 2,500' RPM 2650 Boost 0. I dumped my external tank during the engagement, main fuel cock ON, fuel gauge indicating 100% fuel.

RPM suddenly drops to 2200. Oil pressure 100, seems okay. Oil temp 60. Rad temp is around 40-50, which doesn't seem right. OAT on the mission is 18C, and the engine just quits on me so I have to ditch in the water.

I don't see any carb heat or engine heat anywhere, nor do I see a way to manually close the radiator. So how do I keep the thing warm?

Make sure you are on auto radiator, which you should be by default.

Also, ensure the fuel pressure valve is in the "on" position. You might be loosing fuel pressure, rather than suffering from a cooling issue.

I have not experienced this issue at all in Misison 2.

Incidentally, when you get to mission 3, can you adivse if it is playable for you. I can't complete mission 3 due to FPS losses when the bombers spawn in.

Radiator was on auto. Fuel pressure was fine as indicated by no warning light lit, and I was at very low altitude. I understand the fuel pressure valve to be only necessary when the fuel pressure warning is lit--which it was not.

Mission three is playable for me, but I got torn to shreds because my lack of rearward visibility and no one is kind enough to tell me if a bandit is on my tail.

That said, running VR with everything on low and I disabled wake turbulence. Wake turbulence kills fps for some strange reason.

Radiator was on auto. Fuel pressure was fine as indicated by no warning light lit, and I was at very low altitude. I understand the fuel pressure valve to be only necessary when the fuel pressure warning is lit--which it was not.

Hmm, odd.... I'm out of ideas on that one

That said, running VR with everything on low and I disabled wake turbulence. Wake turbulence kills fps for some strange reason.

interesting, maybe I need to try the mission again, with WTurb turned off.

I just flew Mission 4 and didn't have any problems. My RAD temp dipped down to about 50-55 while RTB, and during descent I saw it drop a little more so I maxed the RPM and ran +8 to keep the temps around 70.

Thing is, how can I heat up the engine like that without increasing my speed?

Do maneuvers. It is not possible to descent with high power settings while maintaining lower speeds.

Even in level flight though, I'll get up somewhere between 250-300. If I'm following AI (as you frequently are in the Big Show) it's not practicable.

Think there are issues with the coolant in all piston aircraft in dcs

Cooling in planes are done quite different than in cars.

Temp is regulated via coolant doors,cowl flaps etc, So in ww2 planes you just simply regulate amount of air passing through radiators.

As you noticed even fully closed radiators arent real closed completely, Fully closed position is often the lesser drag position for those things.

So you cant cruise at too low settings it will over cool engine if you run on low boost.

Same thing with descending, just cant cut throttle and dive in those planes.

Im not sure what to say about higher oil temp than coolant temp but i would say if coolant radiator is first in row and oil radiator is behind it can be possible but i dont know how this is aranged in spitfire.

I would say stick to engine chart limits and cruise at +4 if its still too cold cruise ad higher boost.

I noticed that spit has its radiators even if closed they look still quite open, this may lead to overcooling at low power settings.

If any one has any drawings about oil/ coolent system i would happily look at it :)

Oil system has thermostatic valve which prevent ovecooling so it maby be possible that oil temp will hold up even in low power setting.

Coolant system has thermostatic valve which will cut radiators off if temp will go too low

I have flown in very coold temps in spit in dcs looks like this is not modeled in DCS becouse i bearly could reach 40 celcius at coolant temp and 40C is way too low.

Acording to dcs manual, whne coolant temp is below 80C thermostatic valve is direcing coolant to pump inlet bypassing radiators completely so its not possible drop to 50C at cruise power even +0 Lbs boost is equivalent of 30inch for p-51 which is more than ok for cruise. By look of that, thermostatic valves arent modeled in dcs at all.

By looks of this Cooling is wacked in spitfire by great deal.

So in that case 80C should be rock steady in crusing settings :)

In that case you would have to cut power completely for quite long time to see temps below 70C

Maybe set Carb air filter in operation?

Carb operations ir not working in Spit right now, Only normal operation mod avilable,

But anyway it wont affect engine temps

n piston engines the rule to keep the temperature low is to keep the engine speed low (RPM), at the same time also the air speed helps, more air + cooling. In any case if you want to keep the keep the engine temperature high, I mean from 2500 to 3000 rpm and you will see that it will not descend more drastically even if it is going to dive. Another trick to lower the temperature is to use a mixture rich in petrol but in the Spit it can be regulated, at high rpm to use a rich mixture it helps a lot to cool the engine since the unburned gasoline is from lubricant and refrigerant but at the same time it raises the consumptions and risks to remain dry in the long journeys. Another expedient to cool the engine would be to use only one magnet instead of two, in this way part of the mixture is not burned and acts as a coolant / lubricant, as in the case of the rich mixture. So if I have to advise you something to keep the warm engine: don't go too fast and keep the engine speed high and you'll see that the temperature will always be high.Try.

But the water pump is driven by the engine, high RPM means high coolant flow. In another forum years ago a Spitfire SME cited the old saying "Low revs and high boost, brings you safely home to roost" and said as little as 1800 RPM at +4 psi was considered acceptable on a Mk II.

Think that's definitely overcooling, your coolant wants to be 60-105 degrees usually, the radiator flaps open automatically if auto is left on at 115

Did you notice if you'd been hit? The radiators are quite prone to damage, but the engine can still freeze to death without holes in your plane

EDIT: Scratch that, I'm an idiot, that'd cause overheating^

"Low revs and high boost, brings you safely home to roost"

This is good advice ^

Think that's definitely overcooling, your coolant wants to be 60-105 degrees usually, the radiator flaps open automatically if auto is left on at 115

 

Did you notice if you'd been hit? The radiators are quite prone to damage, but the engine can still freeze to death without holes in your plane

 

EDIT: Scratch that, I'm an idiot, that'd cause overheating^

 

 

 

This is good advice ^

A cording to manual spitfire has thermostatic valves in coolant and oil system which will cut off radiators if temp is lower then 80C.

So even the low power setting for example 0 lbs at 2300 rpm should provide 80C on oil and coolant, there is now way that engine would radiate this amount of heat through engine block and couple meters of houses.

Right now spitfire dont have this implemented yet

I know I have had an engine failure when I was fly back to base at 4 boost and 2700rpm. Engine just powered down. I checked fuel and temps it all seemed fine.

I think what made the engine shut off was my use of full throttle in fights 20 minutes earlier. Lately I have been using just 12 boost which makes dogfight much harder and less fun but my engine has not shut it's self off which is nice.

When someone is flying on MP server which are updating temp according to real, so when ambient temp is around 0 C flying spitfire is impossible at low power settings, no thermostatic valves are modeled in to it so temps will go way too low.

Right now +12 lbs 2850 rpm is probably minimum power to avoid over cooling. Temps should hold at 80 C in spitfire even in case of very low power setting even when you cut throttle and glide.

Manual states that if coolant or oil temp hit 80 C thermostatic valves starts to open radiator circuits if its below 80 C radiators are cut off completely

The Spitfire was never a cold weather machine.

According to some sections in the book "The Big Show", they had to push them to keep the plugs from fouling and in cold weather they even started them up hourly and bring the Temp up to 100 and shut them off so they would be ready to go at all times.

I find the DCS Spitfire works as it should at all times.

Too cold? Give 'er at 12 psi boost for a while and clean up the plugs in the process.

I Love the Spitfire. Perfection (almost).

The Big Show is a great read for Spitfire buffs.

Maybe set Carb air filter in operation?

I tried the Carb Air to see if it worked like Carb Heat and didn't get any effect. I was RTB at 18,000 Ft and I had lost airspeed, VSI, and ALT (all the pitot static instruments) and about 2 minutes after the engine started stuttering like my Cessna 150 did in winter over the Sierra Nevada mountains. But with no Carb Heat, the only thing I could do was descend to warmer air. I'm pretty new to the Spitfire so can anyone tell me if there is a Pitot Heat? :joystick:

Carb operations ir not working in Spit right now, Only normal operation mod avilable,

But anyway it wont affect engine temps

Agreed, but the OAT is affecting the carburetor.

I know I have had an engine failure when I was fly back to base at 4 boost and 2700rpm. Engine just powered down. I checked fuel and temps it all seemed fine.

 

I think what made the engine shut off was my use of full throttle in fights 20 minutes earlier. Lately I have been using just 12 boost which makes dogfight much harder and less fun but my engine has not shut it's self off which is nice.

@Everyone: Just for research, what Altitude was everyone at when they experienced reduced engine RPM?

I have had this only once in the real world and it was a learning experience as my training kicked in, I immediately turned west to my closest airstrip in Northern California, started a descent to maintain flying airspeed, and I went through the checklist in my mind and the problem persisted...and as most pilots do, they do checklist items from memory and then scan the physical checklist to make sure they didn't miss something, and I had missed pulling the carb heat. Within a minute of doing that, the engine reacted just like the textbook training told us, slight decrease in performance followed by a gradual recovery in RPMs...and for the non-pilots, Carb Heat will not give you full 100% normal RPMs as the hot, less-dense air supplied to the engine is thinner and affects total performance. So with this, I continued descent to Placerville, canceled my plans to T/G at Lake Tahoe and with everything ok at Placerville, I RTB'd to MYV.

The Spitfire was never a cold weather machine.

According to some sections in the book "The Big Show", they had to push them to keep the plugs from fouling and in cold weather they even started them up hourly and bring the Temp up to 100 and shut them off so they would be ready to go at all times.

I find the DCS Spitfire works as it should at all times.

Too cold? Give 'er at 12 psi boost for a while and clean up the plugs in the process.

I Love the Spitfire. Perfection (almost).

The Big Show is a great read for Spitfire buffs.

Very nice description! Thanks

Make sure you are on auto radiator, which you should be by default.

Also, ensure the fuel pressure valve is in the "on" position. You might be loosing fuel pressure, rather than suffering from a cooling issue.

 

I have not experienced this issue at all in Misison 2.

 

Incidentally, when you get to mission 3, can you adivse if it is playable for you. I can't complete mission 3 due to FPS losses when the bombers spawn in.

Phil, Reference Mission 3, it's because you're running AMD...just kidding, but in any regard, I enjoy your videos on YouTube. You are one of the best presenters in the DCS Community!

To avoid over cooling we have to wait for thermostatic valves being installed in our spitfires, they were striped down for maintenance, since spitfires's coolers are almost open even at closed position and unrestricted coolant and oil flow is introduced to those we will encounter over cooling no matter what we do at low power settings.

Very nice description! Thanks

Deep Drummer is right.

Pilots need to keep an eye on temps and use a bit of boost now and then to keep the Merlin warm. I know a few online pilots who are now adopting this as an SoP when flying in cold weather or up at altitude, or during extended descents. The good leaders like Fenrir and Wiggy are also reminding their wingmen to do the same,.

It's new to a lot of people who come from other sims which have much more forgiving aircraft modelling which leads to bad habits and poor airmanship. DCS doesn't cut those corners.

Phil, Reference Mission 3, it's because you're running AMD...just kidding, but in any regard, I enjoy your videos on YouTube. You are one of the best presenters in the DCS Community!

You're too kind.

I had problems mission mission 3 BEFORE I uprgaded to AMD, and I had the wake turbulence off. Once I got the new AMD system it ran superbly :)

But I think turning off wake turblulence was really the determining factor.

Phillstyle i saw your videos of Spitfire comparison, i liked it.

Btw try take off with +18lbs boost in spitfire this is fun :)

I tried the Carb Air to see if it worked like Carb Heat and didn't get any effect. I was RTB at 18,000 Ft and I had lost airspeed, VSI, and ALT (all the pitot static instruments) and about 2 minutes after the engine started stuttering like my Cessna 150 did in winter over the Sierra Nevada mountains. But with no Carb Heat, the only thing I could do was descend to warmer air. I'm pretty new to the Spitfire so can anyone tell me if there is a Pitot Heat? :joystick:

 

Pitot heat switch is one of the two on the left side of cockpit elbow panel between the two trim dials.