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J5_Baeumer

Full Throttle Overheating Historical or Not?

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  1. 1. Should WWI engines overheat after prolonged periods of time at full throttle/high RPM?



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As I was flying RoF vintage missions today, a thought reoccurred to me today as I blew a bounce of a SE5a in my Fokker D7F due to me worrying about my rpms and blowing my engine in the near vertical dive.... 

....as I have flown FC in the Fokker and Spad, I have wondered whether or not it is historically accurate to fly these planes full throttle without overheating them.  I notice that the WWII planes overheat at full "combat" throttle after a few minutes.... did these birds overheat also?  It has always seemed a bit odd to me being able to fly around in the WWI birds with the pedal to the metal, hours on end, so to speak.... would not a fighter pilot want to be able to "press" and engine beyond normal limits in the (pardon the pun) "heat" of the battle to get that extra speed to catch or elude or otherwise get a little extra edge over the opponent?

 

Please participate in the poll regarding whether or not engines should model overheating at high RPM.  I invite discussion on the thread as to whether or not modeling overheating at high RPM (unlike RoF) would be historical or not.

Edited by J5_Baeumer
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Bump.  Can we get more community input on this poll?   It seems the Alb Dva is functioning this way but not other planes.  Realism or petal to the metal all day long....unlike WWII modeling that overheats/damages engine after too long at combat throttle....

Edited by J5_Baeumer

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It seems that we can't reply to Baumer's poll so I started a new thread...

 

I voted yes that engines should overheat if flown "balls to the wall" (extra points... where does this phrase originate from?) but I wish I could add the caveat of the exception of rotaries... they're full blast all the time with a little bit of air / fuel mixture adjustment available.

 

I'm not sure if there are differences between the liquid cooled engines. Is the Hisso different from the Mertz or from the Viper as to how long they can be pushed at high power? Is the high compression BMW IIIa more sensitive than the Mertz DIII in the Halb CL.2? Should all liquid cooled engines be subject to overheating? Do the Devs have enough bandwidth (or desire) to model them individually? Would the community be satisfied with a "one size fits all" modeling?

 

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The question is did they even actually overheat in level flight at max speed on a normal day.  Sure they weren't flying around full throttle on the deck for extended periods of time, but once you got to patrol altitude you probably were since the non-supercharged engine wasn't producing as much power in the thinner air.  Last thing I would want in this game is some overheat timer mechanic pulled out of thin air that forces you to throttle back when being chased by say a suicidal camel jockey in his full bore all the time rotary.  If anything is done it should be based off of actual hard engine test data.

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I'll reply to this thread and hopefully a mod can merge both topics and open the poll up to further replies.

 

It is also meant as a reply to the Albatros D.Va overheating bug thread.

 

 

My "educated guess" answer is: no, an aero engine can perfectly run at full throttle for extended periods of time without overheating or suffering any kind of damage beyond perhaps increased wear and tear and a need to have the engine serviced earlier. For the most part, piston engines are built to work at close to their full power output, not to be inoperative or stay at idle power, in much the same way that planes are built to fly and experience airflow rather than sit on the ground.

 

However...

 

  • The most relevant temperature when it comes to engine overheat is cylinder head temperature (CHT), for which we don't have a direct engine probe, not even on air cooled rotary engines where it would be essential. As far as I know, such engine probes didn't exist yet. In theory on liquid cooled engines knowing the temperature of the coolant is enough to ensure safe operation, as the CHT affects it directly.
     
  • Running at high power and low RPM, such as in an extended power climbing turn, are ideal conditions to cause detonation. This isn't some black magic hoo-ha which can only be understood by mechanical experts or aero engine historians with relevant degrees (is that a thing? I want it to be a thing), it's simple physics. If a piston spends more time travelling up and down the cylinder (low RPM) with high enough pressure (full throttle) and high enough temperature (doesn't even need to be overheating), the window for something bad to occur is larger. That something bad is the fuel/air mixture self-igniting before it reaches the spark plug, causing a shockwave which "knocks" on the piston, and can cause damage depending on the severity of the detonation. Since we don't have mixture control on the Albatros, there's no way to manually enrich the mixture to prevent this from happening.
     

This is all very nice, but the in-game technochat for the Albatros clearly says: engine overheat. The engine is not overheating, at least that we know of. Adding CHT as a simple gauge could shed some light on it, but even then the coolant should be directly affected if it is indeed an overheat. And if it's actual detonation, then why isn't it happening with the other Mercedes D.IIIa-powered planes?

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6 hours ago, J5_Hellbender said:

And if it's actual detonation, then why isn't it happening with the other Mercedes D.IIIa-powered planes?

Detonation isn't modeled in the game hop into a ww2 bird crank up the manifold pressure and leave prop pitch at zero and nothing bad happens.

 

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21 hours ago, hrafnkolbrandr said:

Is the "full throttle" available to the pilot actually the "full throttle" that engine is capable of?

 

That's some "out of the throttle" thinking!

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30 minutes ago, J5_Klugermann said:

I didn't experience it while on the JG1 FC server last night. maybe the last update/hotfix addressed it.

 

Downloading, will test it for sure!

Aaaaand it's not been addressed. Problem persists. Overheats after 5 minutes on Stalingrad summer map. (A little longer on Arras.)

Edited by J2_Jakob

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Detonation should be possible when flying a 200HP Halb on full throttle on a low altitude, as this engine had higher Manifold Pressure on 0 alt than the atmosphere press.
I think that some engines would need some "tuning". When running a Brisfit engine on ground, I could actually overcool it, when running on idle.

Flying the D.VIIF on the ground level with the alt throttle applied can damage your engine.

 

BTW: The Oeffag-made Albatroses had an engine cover used for the winter conditions in the Alps

Edited by 1PL-Lucas-1Esk

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Something I can offer in regards to flying around in more modern aircraft with air cooled engines up to 180hp. 

 

They don't overheat in straight and level flight at full throttle, even on very hot summer days, BUT on a hot summer day and/or when the density altitude is over 1000ft - they will absolutely CAN spike in engine heat in a full power climb and you have to closely watch the temp at that point.  The key is that in level flight, the airflow over the engine and radiator is generally enough to do the job cooling.  Also since BOS can not model altitude temperature inversions, you'll never have a case in the game where flying higher should make it more likely that your engine blows.

 

I would argue that if ANYTHING, the temperature related phenomenon that needs to be modeled most for aircraft in this game is wing icing due to visible moisture at low temperatures.

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On 9/27/2019 at 7:26 PM, hrafnkolbrandr said:

Is the "full throttle" available to the pilot actually the "full throttle" that engine is capable of?

On these types of engines, yes. When the throttle body is opened all the way (full throttle) that is the maximum amount of air it can put in the cylinder.  

 

I asked some friends and it would be possible to over heat a water cooled engine in very hot climates.  A rotary would probably not be as susceptible.

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I have noticed this as well and I compensated by flying at about 85 to 90% until I am engaged then to full throttle and full rad, then after engagement to about 80% for a few minutes on full rad until I am satisfied with temp before readjusting rad and throttle.

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S! All

 

This may be a mission editor problem.  For RoF the default temp is 15 degrees C.  For the FC/IL2 series it is 20 or 25 degrees C. Mission makers need to review their air temp.

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1 hour ago, J5_Klugermann said:

Then why does it only happen in the Alb.

Because it is a bug with the Alby, or with the others, one or the other.

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The Pup has the same problem in ROF, but at least you can fly straight at full power. But you have to bring back the throttle in dogfights or she will seize, even in the autumn map (I'm not sure during winter).

 

They should fix the Albatros or then do a very detailed research on each plane to implement power limitation on a plane to plane / engine type basis. Since the latter is very unlikely, they should just fix the Albatros is my opinion. 

 

Any Albatros jockey opened a report bug yet? I’m looking for the day that we have our own bug section.

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16 hours ago, SeaW0lf said:

Any Albatros jockey opened a report bug yet?

 

Yes, I did, but it seems I'm beating a dead horse there (well, it's more just like an occasional prod with a stick)...
Plus, since we don't have our own bug section, we get overrun by WW2 bugs and the post quickly vanishes in the vast wastelands of page 2 and further.

 

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On 10/6/2019 at 4:39 AM, J2_Jakob said:

 


Plus, since we don't have our own bug section, we get overrun by WW2 bugs and the post quickly vanishes in the vast wastelands of page 2 and further.

 

 

LMAO

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Yes, but it would very dependent on the engine. These all need to be modeled with historical accuracy in mind.

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Mikael Carlson does allude that the German high compression engines (in particular here Mercedes D.IIIaü) have problems with temperature when run at full power at low altitude, but he also states being extra careful on his part:

 

https://vintageaviationecho.com/fokker-d-vii/

Edited by hq_Jorri
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On 9/27/2019 at 7:31 AM, II./JG1_Vonrd said:

"balls to the wall" (extra points... where does this phrase originate from?)

 

 

 

 

Here, perhaps

 

 

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5 hours ago, hq_Jorri said:

Mikael Carlson does allude that the German high compression engines (in particular here Mercedes D.IIIaü) have problems with temperature when run at full power at low altitude, but he also states being extra careful on his part:

 

https://vintageaviationecho.com/fokker-d-vii/

Edited 5 hours ago by hq_Jorri

 

I believe you may have hit the nail on the head; although I doubt this engine would go kaput in such short a time, and if not, the modelling seems a bit off if it was the intention of the devs to model this.

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Why is there a Poll on this subject?  The engines either overheated or they didn't as a matter of physical reality, not as a matter of popular consensus.

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Because the subject of this thread has changed from the poll topic I started over a year and several patch updates ago.

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Well considering that even a lawn mower engine can overheat if run full throttle for long enough, I voted yes.  

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On 9/26/2019 at 11:31 PM, II./JG1_Vonrd said:

 

 

I voted yes that engines should overheat if flown "balls to the wall" (extra points... where does this phrase originate from?) but I wish I could add the caveat of the exception of rotaries... they're full blast all the time with a little bit of air / fuel mixture adjustment available.

 

 

 

 

The "balls" were the handle grips of the the throttle, prop and mixture. The "wall" was the firewall. Hence the phrase, "balls to the wall"

Edited by Adam
I F@#$%^ up. That's the reason for the edit! DUH!

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Adam!... you're back? Good to hear from you. (assuming this is J2_Adam).

 

That's the one I was thinking of... but I also came across this:

 

The phrase “balls to the wall” may come with the centrifugal governor of a steam engine, which used spinning ball bearings to adjust a valve limiting the amount of steam entering the engine. As more fuel is put into the engine and more steam produced, the added pressure and centrifugal force of the spinning bearings pulls them outward toward the wall of their housing, subsequently activating a lever and a valve that limits the amount of steam.

 

And Jay Leno:

 

 

Edited by II./JG1_Vonrd
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