Glycol leaks & inline engines the science of...

[Blitzen]

I wonder how the developers & their design of FM has handled glycol coolant leaks in damaged engines? A long time ago i read a book by an ex RAF pilot who stated that if the glycol system was hit , the glycol would boil off quickly & fairly quickly after that the engine would seize. One needed to be aware that one bullet in the system could result in a worrysome situation.I know there are quite a few players here who know quite a lot technically about RR Merlins & by extension inline aircraft engines in general who might be able to fill in the details.The reason I want to know you ask? Well we've all seen quite a few aircraft belching smoke ( & steam?) from bullet hits around the engine & wings that continue to fly & fight long after most pilots would have hit the silk. i will grudgingly accept that a determined if somewhat foolish pilot would fight on with a fuel leak risking life & limb in a desperate attempt to get a last shot into a hated enemy, BUT if its a coolant hit just how long should this AI pilot be able to continue in the fight if we are talking" near" reality? does anyone know if the developers HAVE figured this in & just fudged it a bit ? I know I've had first engine damage & managed to limp quite a ways dependent on how serious the AI has hit me according to an unknown ( to me) damage assessment program this sim runs

  This isn't a very serious whine - I was just wondering...it sort of goes along with the question of why we don't see a lot more bail outs from obviously stricken aircraft?

[-TBC-AeroAce]

If I get a leak of any kind I will run at the first chance. AI on the other hand do not and this could be worked on. 

 

I find the time it takes to break a leaky engine can be random. I have flown for 15 mins I have also had it break instantly. I guess it would be a function of how long it takes to drain and then how long it takes to overheat.

[EAF19_Marsh]

Lot of anecdotal accounts of failure after a minute or 2, depending on flow and engine settings. No idea how it is modeled in the sim.

[Herne]

those screenies are from cliffs of dover ?
 

In this game you know if your engine is damaged even without tech chat, the rpm and MP gauges will flutter, and you may be able to nurse your engine long enough to get you to a friendly field. Lowering rpm and boost seems to help, but depending on the damage, your engine may last seconds, or for quite a few minutes.

 

with regard specifically to glycol, I don't know sorry.

[Blitzen]

28 minutes ago, =FEW=Herne said:

those screenies are from cliffs of dover ?
 

Yes I apologize, but they were the only ones I could find quickly that sort of illustrate my post...CloD has definately takena second spot in my heart after Box introduced VR enabled. still it is a beautiful eye candy sim made better in my opinion with upgraded 'Blitz' version. Someday. perhaps we'll live to see it...VR and the load of new aircraft will make CloD on the same playing field as Box 9 This is not a request or hint for others to dump all over CloD..honestly. Let's not go down that path...again.)

[ZachariasX]

1 hour ago, Blitzen said:

I wonder how the developers & their design of FM has handled glycol coolant leaks in damaged engines? A long time ago i read a book by an ex RAF pilot who stated that if the glycol system was hit , the glycol would boil off quickly & fairly quickly after that the engine would seize. One needed to be aware that one bullet in the system could result in a worrysome situation.I know there are quite a few players here who know quite a lot technically about RR Merlins & by extension inline aircraft engines in general who might be able to fill in the details.The reason I want to know you ask? Well we've all seen quite a few aircraft belching smoke ( & steam?) from bullet hits around the engine & wings that continue to fly & fight long after most pilots would have hit the silk. i will grudgingly accept that a determined if somewhat foolish pilot would fight on with a fuel leak risking life & limb in a desperate attempt to get a last shot into a hated enemy, BUT if its a coolant hit just how long should this AI pilot be able to continue in the fight if we are talking" near" reality? does anyone know if the developers HAVE figured this in & just fudged it a bit ? I know I've had first engine damage & managed to limp quite a ways dependent on how serious the AI has hit me according to an unknown ( to me) damage assessment program this sim runs

  This isn't a very serious whine - I was just wondering...it sort of goes along with the question of why we don't see a lot more bail outs from obviously stricken aircraft?

 

You can try that with your car. It will depend slightly (but less than you think) on how fast you are going. Consider car engines (especially cars of the vintage that might tempt you to try such experiments) are more exposed to airflow than inline engines in high performance aircraft.

 

In a car, you might well be driving hundert miles if you can maintain an even 60 to 80 km/h or so. It happened to me once. I was driving a long time on highway happily while the water pump was broken in my Buick. The moment my sister took the car to the city, it took her two traffic lights to come to a halt with a bang.

 

In an aircraft, while you are leaking coolant, temp does not go up (unless you are at very high power and low airspeed). You will fly until most of it is gone.

 

After that and in absence of airflow (like in the airplane or the car in traffic or uphill, you will notice a sudden, drastic increase in temperature. The temp sensor at this point will be sensing the glowing engine block instead of „nothing“. This is also the time where strange noises do appear. Just before that you will see oil temp creeping steadily off the scale. This is typically the end of your gasket. Depending on power output of the engine, within seconds or some minutes, cylinders will blow. But once your water temp gauge went off scale, repair will be extensive.

[SCG_motoadve]

1 hour ago, =FEW=Herne said:

those screenies are from cliffs of dover ?
 

In this game you know if your engine is damaged even without tech chat, the rpm and MP gauges will flutter, and you may be able to nurse your engine long enough to get you to a friendly field. Lowering rpm and boost seems to help, but depending on the damage, your engine may last seconds, or for quite a few minutes.

 

with regard specifically to glycol, I don't know sorry.

Most of the time when the rpms starts to flutter and you notice its too late and engine is just about to quit.

As soon as you get a hit look behind to see if you are smoking that way you can take immediate action.

[Blitzen]

2 hours ago, ZachariasX said:

 

You can try that with your car. It will depend slightly (but less than you think) on how fast you are going. Consider car engines (especially cars of the vintage that might tempt you to try such experiments) are more exposed to airflow than inline engines in high performance aircraft.

 

In a car, you might well be driving hundert miles if you can maintain an even 60 to 80 km/h or so. It happened to me once. I was driving a long time on highway happily while the water pump was broken in my Buick. The moment my sister took the car to the city, it took her two traffic lights to come to a halt with a bang.

 

In an aircraft, while you are leaking coolant, temp does not go up (unless you are at very high power and low airspeed). You will fly until most of it is gone.

 

After that and in absence of airflow (like in the airplane or the car in traffic or uphill, you will notice a sudden, drastic increase in temperature. The temp sensor at this point will be sensing the glowing engine block instead of „nothing“. This is also the time where strange noises do appear. Just before that you will see oil temp creeping steadily off the scale. This is typically the end of your gasket. Depending on power output of the engine, within seconds or some minutes, cylinders will blow. But once your water temp gauge went off scale, repair will be extensive.

Lovely answer...this happened on two cars i have owned .On one a '46 MGTC the radiator tap rattled loose while I was driving down the Santa Ana freeway to visit my then girlfriend,when just as I exited the off ramp close to her house there was  more of a clunk then a bang & a most unpleasant rattling from the now more or less dead engine. I was able to push the car to just in front her house , where it sat for some weeks while I tried to scrounge enough to get it fixed...Needless to say this did nothing to ingratiate me with her father...

 A Few years later something similar happened to my '52 Morgan, but this time it blew on the off ramp near the then only Morgan repair shop in LA, Scardi Motors then at Pico & Sepulveda...

 English sports cars lord luv-em...i'd be a richer man today if I could have avoided them. I remember the long drives between LA & san Francisco in one or the other of them, with my stomach in a knot & praying I'd make it all the way down Highway 101 in one piece. Luckily i didn't have to worry about being miles behind enemy lines nursing a plane that was trailing cooland for miles out the back and enemy pilots intent on me not making it...What that would do to my stomach is something I don't wish to contemplate...

Oh yes now I own & drive a 69 Morgan and yes it threw a rod & much more two years ago, but now ( fingers crossed) it is running beautifully...But age doesn't necessarily mean maturity.

Edited May 1, 2018 by Blitzen

[ZachariasX]

24 minutes ago, Blitzen said:

Lovely answer...this happened on two cars i have owned .On one a '46 MGTC the radiator tap rattled loose while I was driving down the Santa Ana freeway to visit my then girlfriend,when just as I exited the off ramp close to her house there was  more of a clunk then a bang & a most unpleasant rattling from the now more or less dead engine. I was able to push the car to just in front her house , where it sat for some weeks while I tried to scrounge enough to get it fixed...Needless to say this did nothing to ingratiate me with her father...

 A Few years later something similar happened to my '52 Morgan, but this time it blew on the off ramp near the then only Morgan repair shop in LA, Scardi Motors then at Pico & Sepulveda...

 English sports cars lord luv-em...i'd be a richer man today if I could have avoided them. I remember the long drives between LA & san Francisco in one or the other of them, with my stomach in a knot & praying I'd make it all the way down Highway 101 in one piece. Luckily i didn't have to worry about being miles behind enemy lines nursing a plane that was trailing cooland for miles out the back and enemy pilots intent on me not making it...What that would do to my stomach is something I don't wish to contemplate...

Oh yes now I own & drive a 69 Morgan and yes it threw a rod 7 much more two years ago, but now ( fingers crossed) it is running beautifully...

 

 

Lovely car! One thing you learn about british vintage cars when you drive them is when they are not leaking oil, then it is time for a refill.

 

I know that particular feeling when you start to wonder how far you‘re gonna make it. But this can happen also in American cars of the era. You really get to know each of their parts persnonally.

[Blitzen]

35 minutes ago, ZachariasX said:

 

Lovely car! One thing you learn about british vintage cars when you drive them is when they are not leaking oil, then it is time for a refill.

 

I know that particular feeling when you start to wonder how far you‘re gonna make it. But this can happen also in American cars of the era. You really get to know each of their parts persnonally.

i remember reading somewhere that British Merlins leaked great gobs of oil.British ground crews just accepted it as S.O.P. If I remember correctly it occurred primarily cooling down after flights when the oil was hot.I can only assume that this oil was caught and re-used , but I'm not sure.I also don't know if the American  re-engineered Packard Merlins with better designed gaskets etc., in P-51's had the same proclivity...

[7.GShAP/Silas]

42 minutes ago, ZachariasX said:

 

Lovely car! One thing you learn about british vintage cars when you drive them is when they are not leaking oil, then it is time for a refill.

 

 

Just like helicopters then.

[ZachariasX]

45 minutes ago, Blitzen said:

i remember reading somewhere that British Merlins leaked great gobs of oil.British ground crews just accepted it as S.O.P. If I remember correctly it occurred primarily cooling down after flights when the oil was hot.I can only assume that this oil was caught and re-used , but I'm not sure.I also don't know if the American  re-engineered Packard Merlins with better designed gaskets etc., in P-51's had the same proclivity...

 

Is that so? AFAIK even the Germans thought of the Merlin as a „Rolls Royce“ in the positive sense of the word.

 

However, manufacturing tolerances back then are rather different from today, and this is also reflected in the used oil grades. For instance I do have an original, unrestored 427 V8 in my American 69‘er and you use 20W 40 oil to keep it running best. I mean, you can use modern grade 10W 40, but you will burn a quart of it for every 50L of burnt gasoline. (If I only had 100LL Avgas!) If you do so, it basically becomes a hybrid engine burning gas and oil. The gaps are too big inside engine to hold the thin oil. This also applies for anyone cooking their engine and getting a very low oil pressure as a consequence. Lubrication was abyssmal in these times. (Also what concerns fuel quality. Octane rating does not say in the least how good your fuel is, else Diesel would be perfect fuel.) This means it really depends on how nice you are to those engines they‘ll use a lot of oil quickly and spray it everywhere. But that‘s not really the kind of royal leaking of your original DB6 engine or Jag E-Typer 12 cylinder engine. (If you want an E-Type for real road time, get the 6 cylinder, trust me on this!)

 

I would however guess that refurbished Merlins (and especially DB601/5) indeed are up to far better standards today than back then, featuring todays tolerances for todays lubrication. Else they wouldn‘t get 3500 hp from them at Reno.

[69th_chuter]

An interesting comment about the oil use differences of 10W40 and 20W40 as at operating temp both are 40 weight. 

 

Also, puncturing the cooling system would immediately cause a loss of system pressure which would cause the coolant to start boiling.  Because pressurized cooling systems require pressure to operate under load this would reduce the efficiency of the cooling system noticeably and would lead to the loss of coolant at a faster rate than just the leak, so, depending on the cooling load/cooling capacity at the time of puncture and beyond you may or may not notice an immediate rise in temperature.  At altitude the coolant boil off might be dramatic.

[Venturi]

Coolant system leak behavior will depend on if it is pressurized or not. Pressurized systems will fail quickly, non pressurized systems will fail slightly less quickly. Pressurized systems are designed to cool under pressure and will quickly lose this ability when pressure is lost. They will also vent the coolant more quickly. But the difference will be only a matter of a minute or two minutes at most. The Venturi effect will draw the coolant out of the system if the radiator is hit, in addition to any pressurization effect, so even non pressurized systems will fail within a minute or two. As soon as a vapor lock hits the water pump, it’s all over, you don’t need to have complete coolant loss. 

 

Coolant leaks are spectacularly bad for a high output engine without any airflow over it.

Btw, this is how the real-life “Black-6” 109G-2 ended her career. It only took a moment...

[ZachariasX]

Indeed. If you are not actually seeing the coolant steam away, there‘s really only oil temp and pressure indicaters that may announce you the very bad news. And this only really in unpressurized cooling systems, as the others fail too soon. The problem there is also that oil temp and pressure as well as water pressure systems are often far away from the damage in the system, all the way at the bottom just after the pump. They will show you readings from coolant (and oil!) that does not reach the cylinders anymore. This coolant will naturally not get very hot anymore, showing everything in the green.

 

What can happen is that the oil gets hot and less viscous, showing an increase in temp and decrease in pressure, while water still remains in the green. This is your last straw.

 

As soon as coolant is gone, the excessive heat from the engine block creeps down to the water sensor causing a sudden spike of temp off the scale. By then the gasket is gone and galling underway.

 

You might be able to save the engine block, but the whole rest has to be replaced then. If that was your Aston DB6 engine, all it takes then is about $200kto make it new. Imagine a Daimler DB605...

[Blitzen]

So ( and remember this is just for fun) is there any way to test what is happening in the sim? Probably impossible I guess, but it does seem to me that the AI guys get quite a run after being hit many times.with a lot of smoke from a lot of places,& they are very reticent about leaving their aircraft & taking to parachutes even when a wing is fully engulfed in flames...brave men those Ai chaps!

[Blitzen]

1 hour ago, ZachariasX said:

Indeed. If you are not actually seeing the coolant steam away, there‘s really only oil temp and pressure indicaters that may announce you the very bad news. And this only really in unpressurized cooling systems, as the others fail too soon. The problem there is also that oil temp and pressure as well as water pressure systems are often far away from the damage in the system, all the way at the bottom just after the pump. They will show you readings from coolant (and oil!) that does not reach the cylinders anymore. This coolant will naturally not get very hot anymore, showing everything in the green.

 

What can happen is that the oil gets hot and less viscous, showing an increase in temp and decrease in pressure, while water still remains in the green. This is your last straw.

 

As soon as coolant is gone, the excessive heat from the engine block creeps down to the water sensor causing a sudden spike of temp off the scale. By then the gasket is gone and galling underway.

 

You might be able to save the engine block, but the whole rest has to be replaced then. If that was your Aston DB6 engine, all it takes then is about $200kto make it new. Imagine a Daimler DB605...

Just the little 1600cc English Ford Cortina engine rebuild wasn't cheap. Of course during the war technical help was plentiful & cheap. I don't know what RAF Erks or the Luftwaffe "Black Men" were paid but it couldn't have been much...but probably better than the Soviets paid their Merry Motherland crews...

[ZachariasX]

13 minutes ago, Blitzen said:

Just the little 1600cc English Ford Cortina engine rebuild wasn't cheap. Of course during the war technical help was plentiful & cheap. I don't know what RAF Erks or the Luftwaffe "Black Men" were paid but it couldn't have been much...but probably better than the Soviets paid their Merry Motherland crews...

 

These „black men“ are 100% caucasian Swiss army technicians servicing a Swiss 109 E3 in on the airfield of Thun (now LSZW). Seems all it took was the nice summer of 1940 and General Guisan ended up with Buffalo Soldiers.

 

If people just realized how little difference it takes, it could have saved us from a lot of misery...

Edited May 2, 2018 by ZachariasX
typo

[Blitzen]

That is great info on the photo-interesting. Still it is a beautiful picture that went along with my point. I think.  

[ZachariasX]

6 hours ago, Blitzen said:

That is great info on the photo-interesting. Still it is a beautiful picture that went along with my point. I think.  

 

Those E3 were good aircraft and were used throughout the war. The 109 G6 however were of such poor quality that the engine would fail in a very short time and they had to be grounded. The engines were so bad, that they remanied largely unflyable and saw hardly any use. So much for late German aircraft and max. boost ratings.

Edit: As they were traded for a fancy new radar equipped Bf110, the Germans certainly picked from the bottom of the barrel...

Edited May 3, 2018 by ZachariasX
correction