Escorts could only stay with bombers for 20-40 minutes?

[GScholz]

I've been lucky enough to have seen both up close. The Buchon's nose is not "way bigger". Very different yes, but not bigger. The Merlin and DB 605 are almost identical in size. The DB is just an inverted-V and the 109's fuselage is designed around it, not the Merlin. That's why the Merlin fit is so bad. The 109's fuselage is wide at the bottom and narrow on top to accommodate an inverted-V engine. Exactly the opposite of the Spitfire. Both aircraft are designed around their engines. The Merlin 60-series is 3.7 inches longer than the DB 605. The difference in height and width is one inch or less.

[shift8]

Just want to point out something for the previous WEP discussion. This is not a response to any specific point of view, just something I didnt see mentioned specifically, it it was and I missed it, my bad.

The WEP limits on 109s, Spits, P-51s, P-40s etc etc etc. Are in no way thermal limits by any stretch of the imagination. The five minute time limit or 10 minute time limit is a semi-arbitrary number intended to guarantee a certain length of engine life at a operational level. We are talking multi mission engine life, not omg you ran the engine at WEP for 5 min 1 second BOOM.

There are an overwhelming number of accounts and tests, aside from general knowledge of engines, that back this up. Pilots routinely ran WEP for periods greater than 15-20min with no adverse effects during that specific mission. Some of the engine tests run by the AAF were for period of over 7 hours, just to make sure it wasnt going to ruin the engine. I am sure there are German tests of a similar nature. It certainly wore the engine out faster, but it almost never caused failure during combat. There is a reason for example, that the 5min WEP time on the P-51B of 67inches is still 5min at 75 or 72 inches. Same goes really with almost any WEP setting. You will notice they keep the arbitrary time limits despite upping power significantly.

[Dawger]

Just want to point out something for the previous WEP discussion. This is not a response to any specific point of view, just something I didnt see mentioned specifically, it it was and I missed it, my bad.

The WEP limits on 109s, Spits, P-51s, P-40s etc etc etc. Are in no way thermal limits by any stretch of the imagination. The five minute time limit or 10 minute time limit is a semi-arbitrary number intended to guarantee a certain length of engine life at a operational level. We are talking multi mission engine life, not omg you ran the engine at WEP for 5 min 1 second BOOM.

There are an overwhelming number of accounts and tests, aside from general knowledge of engines, that back this up. Pilots routinely ran WEP for periods greater than 15-20min with no adverse effects during that specific mission. Some of the engine tests run by the AAF were for period of over 7 hours, just to make sure it wasnt going to ruin the engine. I am sure there are German tests of a similar nature. It certainly wore the engine out faster, but it almost never caused failure during combat. There is a reason for example, that the 5min WEP time on the P-51B of 67inches is still 5min at 75 or 72 inches. Same goes really with almost any WEP setting. You will notice they keep the arbitrary time limits despite upping power significantly.

You are absolutely correct. The book time limits were aimed at prolonging service life if the engine.

To paraphrase " If you probably arent going to use the engine again, there are no limits"

A better modeling would be to allow unlimited WEP ( except on thise aircraft with injected fluid ) but inflict damage to the engine if certain temperature limits were exceeded. Allow the player to heat the engine up to the limit and then if he pulls the power back and cools it down he can use the WEP some more. But if he exceeds the critical temperature, then detonation occurs, inflicting damage to the engine and power loss or failure of the engine.

This sort of modeling may be beyond the realism limits HTC desires from a gameplay standpoint since the player can unwittingly blow up his own engines.

[GScholz]

Allow the player to heat the engine up to the limit and then if he pulls the power back and cools it down he can use the WEP some more.

That's exactly how it works in AH, except for not blowing up, just WEP shutting itself off. All planes have unlimited WEP, but with different cool down intervals. In the DB 605 powered rides the WEP cycle is typically 10/5 meaning you get max 10 minutes of WEP before you have to cool down, but it only takes 5 minutes to "recharge" the WEP completely. If you run on MIL power or less for one minute you get to use WEP for another two minutes. If you run out of WEP in a critical moment just keep hitting the WEP button and you will get WEP back for a couple of seconds at a time. The Merlins in this game have 5/10 or 5/15 cycles if I remember correctly.

As Shift8 points out WEP really has nothing to do with engine heat. Unless your in a long steep climb there is very little chance you're going to overheat the engine at any power setting. At high speed the radiator/cowl flaps are almost closed on most planes even at max power.

[Krusty]

Just want to point out something for the previous WEP discussion. This is not a response to any specific point of view, just something I didnt see mentioned specifically, it it was and I missed it, my bad.

The WEP limits on 109s, Spits, P-51s, P-40s etc etc etc. Are in no way thermal limits by any stretch of the imagination. The five minute time limit or 10 minute time limit is a semi-arbitrary number intended to guarantee a certain length of engine life at a operational level. We are talking multi mission engine life, not omg you ran the engine at WEP for 5 min 1 second BOOM.

There are an overwhelming number of accounts and tests, aside from general knowledge of engines, that back this up. Pilots routinely ran WEP for periods greater than 15-20min with no adverse effects during that specific mission. Some of the engine tests run by the AAF were for period of over 7 hours, just to make sure it wasnt going to ruin the engine. I am sure there are German tests of a similar nature. It certainly wore the engine out faster, but it almost never caused failure during combat. There is a reason for example, that the 5min WEP time on the P-51B of 67inches is still 5min at 75 or 72 inches. Same goes really with almost any WEP setting. You will notice they keep the arbitrary time limits despite upping power significantly.

That's not true. The limits are thermal in nature because running the engine that way can over-stress seals, bearings, joints, moving parts not designed to move 200 rpm faster than they should, and so forth. There is a component of prolonging service life, yes. However, saying it's not thermal is just dishonest. You could say "It's not the absolute melting point of the engine" and have an argument, but there was a lot of variation from engine to engine. The standards and operating limits were there as a baseline. They were only guaranteed to behave in predictable manners up to those specifications. You COULD run an engine at higher RPM for twice as long as you should, but you COULD also cause something to fail and never make it back. Also, there is a very inter-connected relationship between the various systems on a plane. It's not just more power. The power has to be properly translated to a gearbox. That gearbox can only work within certain inputs/outputs at certain gearings. That output will go to a prop shaft and that prop shaft will have an oil-based governor on it limiting RPMs. Those RPMs can only work so well with a prop designed for efficiency within a certain range.

Just last night I was reading a comment about engine tests in WW2 where the end result was deemed (to paraphrase) "Running at these settings will produce no more power or performance but will significantly shorten the life of the engine."

Remember: Engines are complex machines. You can run them improperly. Running them WRONG doesn't make them uber or super, it just means you're being reckless and/or ignorant. Many WW2 pilots never went into WEP their entire career, even through multiple combats. Many just firewalled the throttle to the max allowed (non-wep) setting for the duration of combat and only afterwards did they think about throttling back.

[Vraciu]

Unlimited WEP is gone now.  HiTech coded it out.

The DB nose is sleeker and has better aerodynamics than the Merlin on the 109/1112.  It is significant.  You can see it in your picture, GS. 

The Merlin cowling is a big fat block that protrudes below the bottom of the wing.  It also is a straight line at a right angle from the windscreen. 

The DB tapers toward the nose from the windscreen and meets the lower edge of the wing without protruding.  It is also longer as you stated. 

The net result is a far sleeker, more aerodynamic nose on the DB 109, particularly F-K.

[Dawger]

That's exactly how it works in AH, except for not blowing up, just WEP shutting itself off. All planes have unlimited WEP, but with different cool down intervals. In the DB 605 powered rides the WEP cycle is typically 10/5 meaning you get max 10 minutes of WEP before you have to cool down, but it only takes 5 minutes to "recharge" the WEP completely. If you run on MIL power or less for one minute you get to use WEP for another two minutes. If you run out of WEP in a critical moment just keep hitting the WEP button and you will get WEP back for a couple of seconds at a time. The Merlins in this game have 5/10 or 5/15 cycles if I remember correctly.

As Shift8 points out WEP really has nothing to do with engine heat. Unless your in a long steep climb there is very little chance you're going to overheat the engine at any power setting. At high speed the radiator/cowl flaps are almost closed on most planes even at max power.

There is a time limit to WEP in Aces High so you are incorrect in that respect.

Higher power levels increase the likelihood of detonation by "hot spots" in the induction system and cylinder.

The areas that produce the hot spots that cause detonation are not directly influenced by the normal cooling system. The heat from these areas must dissipate into the surrounding structure which is cooled directly by the liquid or air cooling. The cooling system, by the rules of physics, can only reduce overall temperature of the engine components through thermal transfer. It cannot directly address small hot spots created deep in the induction system and cylinder where they are likely to cause detonation to occur.

This is why Anti Detonation Injection fluids(generally water alcohol blends) were used on many aircraft. The fluid directly cooled the induction system and cylinder, allowing operation at higher boost levels because it help delay the formation of hot spots.

You can create detonation and engine damage on an ice cold engine by cramming the throttle forward with the mixture leaned. Rich mixture is required at high power settings because the excess fuel serves the same function as Anti Detonation Injection fluid, cooling of the induction system to reduce hot spots.

The reason for time and temperature limits when running at power levels above normal rated power is because the temperature of the engine is rising. The cooling system cannot keep the engine at its "cruise" temperature and as the overall engine temperature rises, the greater the likelihood of a hot spot in the engine causing detonation. This is because there is a decrease in the rate of thermal transfer from the combustion chamber to the cooling system.

[shift8]

That's not true. The limits are thermal in nature because running the engine that way can over-stress seals, bearings, joints, moving parts not designed to move 200 rpm faster than they should, and so forth. There is a component of prolonging service life, yes. However, saying it's not thermal is just dishonest. You could say "It's not the absolute melting point of the engine" and have an argument, but there was a lot of variation from engine to engine. The standards and operating limits were there as a baseline. They were only guaranteed to behave in predictable manners up to those specifications. You COULD run an engine at higher RPM for twice as long as you should, but you COULD also cause something to fail and never make it back. Also, there is a very inter-connected relationship between the various systems on a plane. It's not just more power. The power has to be properly translated to a gearbox. That gearbox can only work within certain inputs/outputs at certain gearings. That output will go to a prop shaft and that prop shaft will have an oil-based governor on it limiting RPMs. Those RPMs can only work so well with a prop designed for efficiency within a certain range.

Just last night I was reading a comment about engine tests in WW2 where the end result was deemed (to paraphrase) "Running at these settings will produce no more power or performance but will significantly shorten the life of the engine."

Remember: Engines are complex machines. You can run them improperly. Running them WRONG doesn't make them uber or super, it just means you're being reckless and/or ignorant. Many WW2 pilots never went into WEP their entire career, even through multiple combats. Many just firewalled the throttle to the max allowed (non-wep) setting for the duration of combat and only afterwards did they think about throttling back.

No this is not how it works.

WEP ratings are not over the limits of the engine. If they were over the specific thermal or mechanical limits, the engine would outright fail. ALL power ratings, and in fact ALL engineering rating in general, are designed to guarantee certain ranges. For example, the 9G limit on the F-15 is not even close to the actual hard limit. Running WEP for longer than 5min will reduce the life of the engine over the long haul. It does not (usually) causes imminent failure.

The 5min rating for the Mustangs WEP, or a 109s 10 min of MW50 is not a magical structural or thermal limit. It is a number chosen because the designers/operators want the plane to last a certain number of missions or flight hours. We are talking 2-5 missions etc. IE: unless the engine is poorly maintained or already at its limits, the engine is not likely to fail simply from running we WEP for too long. The engine is not a time bomb that is headed for doom when the WEP is thrown on. Yes, it is running harder. Yes that causes more stress on the engine. And yes that stress wears out parts. But NOT during a single mission. All the ratings are relative short of violating the literal real limits of the engine.

Like I said before, you need only look at the available data. There are tons of pilots reports, and official tests regarding this. There is a reason that engine with no fuel or coolant change consistently had their WEP rating upped but the time periods remained the same. The only thing that matters is if the users think the loss in long term engine life is worth the power rating. Even simpler evidence is in most aircraft's general performance testing. Time to Climb, and Max climb rate charts were performed at WEP. It take most planes well over 5min or even 30min to finish such a test at max power.

http://www.wwiiaircraftperformance.org/150grade/p-47-66inch.jpg

http://www.wwiiaircraftperformance.org/mustang/combat-reports/353-hinchey-14nov44.jpg



I dont mind the AH WEP model too much because attempts to made decent thermodynamic systems in other sims have failed laughably. Its not easy to model. Its one of those things that if you try usually results in less realistic result than a simplified system like in AH. Although since AH has been brought up, I would be of the opinion that WEP should be indefinite for at least the first sortie in a plane. If you rearm, then maybe some penalty should exist after several reuppings of the same plane. Then again, you could always argue the engine got replaced as needed.

[GScholz]

Just did a test. Upped a Spit8 flew around shooting drones for 5 minutes until the WEP ran out. After waiting about three seconds I got one second of WEP back, just as I should with the 5/15 WEP cycle. I waited longer then engaged WEP again and got several seconds worth. Then I did a slow half-loop and waited some more, and got WEP back for longer. It works just like it used to. In the video I never manually turn WEP off:

[GScholz]

The DB nose is sleeker and has better aerodynamics than the Merlin on the 109/1112.  It is significant.  You can see it in your picture, GS.

This is true. More bumps is the last thing a 109G needs. However, despite that the Buchon is the better performer of those two 109s in the picture. The Merlin's extra 170 hp made up for the less than ideal engine fitting.

[Vraciu]

Just did a test. Upped a Spit8 flew around shooting drones for 5 minutes until the WEP ran out. After waiting about three seconds I got one second of WEP back, just as I should with the 5/15 WEP cycle. I waited longer then engaged WEP again and got several seconds worth. Then I did a slow half-loop and waited some more, and got WEP back for longer. It works just like it used to. In the video I never manually turn WEP off:

Try it in a Mustang.  Eventually you get no more WEP.

HiTech posted elsewhere that unlimited WEP in AH2 was a bug that he fixed in 3.  At some point you lose it for good and must replane to get it back. 

[Vraciu]

This is true. More bumps is the last thing a 109G needs. However, despite that the Buchon is the better performer of those two 109s in the picture. The Merlin's extra 170 hp made up for the less than ideal engine fitting.

Guess so.  Although the K probably destroys the Buchon. 

[GScholz]

Try it in a Mustang.  Eventually you get no more WEP.

HiTech posted elsewhere that unlimited WEP in AH2 was a bug that he fixed in 3.  At some point you lose it for good and must replane to get it back.

OK so I just did. Upped a D-Pony. Flew it on WEP for five minutes until it shut down. Cruised on MIL for ten minutes to let it cool down. Watched the temp needle go back down to normal. Turned WEP back on for another full five minutes. Vraciu, I want those 20 minutes of my life back! 

[icepac]

Certain planes depended on "consumables" for thier "wep".

I believe those are the ones that hitech coded for a total wep time limit.

This goes back to warbirds.

[Dawger]

OK so I just did. Upped a D-Pony. Flew it on WEP for five minutes until it shut down. Cruised on MIL for ten minutes to let it cool down. Watched the temp needle go back down to normal. Turned WEP back on for another full five minutes. Vraciu, I want those 20 minutes of my life back! 

I would bet you don't get a third five minutes