Will the P-40 engine limits be fixed at some point, or it will just be left as it is now? :(

[EduardoMCfly]

I like flying the P-40, I feel very good when shooting down a target with a far less competitive aircraft.... It just makes me feel a better pilot! But the thing is the engine.... There is no need to explain the problem abut the engine, it has been discussed 1000 times, so will the engine performance and timers be fixed in the future, or the P-40 is gonna be left as it is right now?

[BlitzPig_EL]

Perhaps if we get a later version, or move to a theater where they were operated by US or British Commonwealth air forces that ran them at higher limits without issue (just like the Russians did in real life).

[EduardoMCfly]

11 minutes ago, BlitzPig_EL said:

Perhaps if we get a later version, or move to a theater where they were operated by US or British Commonwealth air forces that ran them at higher limits without issue (just like the Russians did in real life).

I know, but what I'm trying to do is to give the E variant a 2nd chance, because we shoudn't just avoid the problem by just getting a new better plane.... We can already do that, instead, is better to have all aircraft simulated properly so we can enjoy them all at their max! ?

[Voyager]

Need to find the documentation to drive a change. Or build a usable universal piston engine failure model to replace the timer system with. 

 

Might be a good thesis project for some intrepid engine engineering postgrad some day. 

[EduardoMCfly]

20 minutes ago, Voyager said:

Need to find the documentation to drive a change. Or build a usable universal piston engine failure model to replace the timer system with. 

 

Might be a good thesis project for some intrepid engine engineering postgrad some day. 

In real life the engine could handle a lot more than in performance charts, in fact, real pilots usually exceeded the engine limitations while in combat. 

Also if you by accident push the MP too far by accident, that usually didn't end up with your engine blowing apart....  

[CountZero]

your best solution is to just turn on undestructable option in realisam settings, then engine timers dont have any effect.

you can still be shot down by bulets and so on, brake engine by overheating or run out of fuel, only thing is you dont brake apart when you colied with ground. 

if they have problems with finding way and time to dim nav lights i doubt you gona get any overhaul of engine timer behavior any time sone or ever... best to hope is option like undestructable but that only turns off timers, so it can be used in MP also.

Edited January 13, 2022 by CountZero

[EduardoMCfly]

4 minutes ago, CountZero said:

your best solution is to just turn on undestructable option in realisam settings, then engine timers dont have any effect.

you can still be shot down by bulets and so on, brake engine by overheating or run out of fuel, only thing is you dont brake apart when you colied with ground. 

if they have problems with finding way and time to dim nav lights i doubt you gona get any overhaul of engine timer behavior any time sone or ever... best to hope is option like undestructable but that only turns off timers, so it can be used in MP also.

I mean... It's not a bad option, but certainly not ideal, I really hope it gets fixed at some point in the future.....  

[CAFulcrum]

19 hours ago, CountZero said:

your best solution is to just turn on undestructable option in realisam settings, then engine timers dont have any effect.

you can still be shot down by bulets and so on, brake engine by overheating or run out of fuel, only thing is you dont brake apart when you colied with ground. 

if they have problems with finding way and time to dim nav lights i doubt you gona get any overhaul of engine timer behavior any time sone or ever... best to hope is option like undestructable but that only turns off timers, so it can be used in MP also.

 

The whole concept of artificial engine timers to reflect service manual 'operating limits' is anti-simulation.  Having a 'no engine damage' option would be okay, but I'd rather see the devs just give up on this at some point -- leave in actual engine breaking, like overreving and hard limits on things like WEP, but the stuff where it's strictly done to improve the life of the engine is way beyond the level of simulation most people are playing.  If a historical squad wants to limit their players in a scenario that's one thing, but I don't see 'but then everyone will fly around at full power' as a reason to instill a supposedly historical simulation element on gameplay that is already totally a-historical.  I'd rather have random failures as an option than this, to simulate the same general 'old engines that are pushed too long tend to break.'

 

It's not even an issue of making to p40 more 'competitive' either imo; the p40 does pretty well as is when flown right.  It just seems like the big 'limiting factor' with pushing the engine too hard should be either overheating or fuel consumption, not engine wear that magically destroys your engine because you went over some arbitrary time limit at a certain speed according to a suggestions sheet to improve engine life.

[SAG]

If the whole idea with these engine timers is to simulate some "service life" of an engine, then I would like to see much more lenient timers plus a mission/Server setting called "maintenance quality" (or something like that) that could alter these timers, 0.25, 0.5, 100% etc. This could also be great for online campaigns for server admins to determine the limits of the available planes, according to destroyed factories, infrastructure, etc. It could open a lot of gameplay possibilities I believe.

[[CPT]Crunch]

We have limiters on stick pull and roll rates at speed, so why not introduce a throttle limiter where you can't accidentally go past the breaking point, unless you command it so.  Plenty of other hi fi sims allow you an afterburner limiter so you don't accidentally keep entering it, since our throttle controller axis's lack the appropriate limiters, gates, or other physical feedback indication.  That would allow you to at least fight it to the maximum within the safe limits without babysitting it to the extreme just to prevent an instant blow up.  Already have a similar set up on mig flaps, not?

[Danziger]

Hopefully we'll get a later P-40N model when we move to the Pacific and they will be able to address bugs with the E.

[4thFG_Cap_D_Gentile]

Someone somewhere once claimed the 1710 in game engine limititations was due to Russian avgas cumbersome quality in the year of the P-40's introduction over east. Makes sense alright! But the arrogance is beyond me that on later dated airfields where as 40's are parked next to Spit 5's & Hurricane II's, which gets their avgas from the very same bowsers as the 40 on that airfield, but they can pull full MP without burning their engines, in a heartbeat,not like the 40 because of the silly timer and limitations on the superb US aero engine.

Edited January 14, 2022 by Ojisan_Mjoelner

[Dakpilot]

Shame that our "superb US aero engine" only came fitted with an MP gauge that only reads to 50" and has no manifold pressure regulator.. Which is historically correct for our E-1, what we need is a later model/ version 

 

Cheers, Dakpilot 

[4thFG_Cap_D_Gentile]

Tex Hill among others had that "50 dial all the way up to 20 inches, those were E1's picked up in west Africa

[Dakpilot]

6 hours ago, Ojisan_Mjoelner said:

Tex Hill among others had that "50 dial all the way up to 20 inches, those were E1's picked up in west Africa

 

Where did you read that? 

 

Cheers, Dakpilot 

[EduardoMCfly]

16 hours ago, Dakpilot said:

Shame that our "superb US aero engine" only came fitted with an MP gauge that only reads to 50" and has no manifold pressure regulator.. Which is historically correct for our E-1, what we need is a later model/ version 

 

Cheers, Dakpilot 

Yes, it would be cool if they add another later variant of the P-40, BUT, first they have to fix the one that we currently have in game or maybe at the time they release another variant, fix simultaneously the E-1 that we currently have....   

[Voyager]

On 1/15/2022 at 12:29 AM, Dakpilot said:

 

Where did you read that? 

 

Cheers, Dakpilot 

There is a glorious letter from the Allison Engineering team asking pilots to please stop doing that I saw a while back. I don't have a copy or link handy, unfortunately, but it was quite memorable. 

 

I think I found it burried somewhere in the WWII Aircraft Performance website. That was also where they've got a copy of that P-51 after action report where the guy was running his engine at 75" for some ridiculous length of time chasing a 262, and convinced that he could shave caught the guy if he just had access to the 81" setting the Brits were using.

 

One thing that also struck me is the reported airspeeds are also absolutely impossible. I wonder if there is a transonic effect that really screws with air speed readings in period planes that isn't being modeled yet? 

[354thFG_Drewm3i-VR]

On 1/14/2022 at 4:03 PM, Dakpilot said:

Shame that our "superb US aero engine" only came fitted with an MP gauge that only reads to 50" and has no manifold pressure regulator.. Which is historically correct for our E-1, what we need is a later model/ version 

 

Cheers, Dakpilot 

Allison themselves later approved a WEP of 60" for the 1710-39 engine with 8:8:1 ratio blower gears found in the p-40e version we have. Unofficially, they acknowledged NA Kittyhawk squadrons with the same engine running over 70" for up to 15 minutes in a memo with no reported failures, HOWEVER they did warn that later engines with different ratio blower gears could not be boosted above 57" reliably. It's all documented and I've read all the primary documents myself as they've been posted here and on ww2aircraft.net.

Edited January 17, 2022 by -332FG-drewm3i-VR

[Dakpilot]

People keep quoting things that simply do not apply to the P-40E-1  of 1941 which arrived in time for Battle of Moscow as modelled and represented in 'our' P-40. 

 

Nothing wrong with wanting a later model... but there has been so much disinformation, whataboutisms, and generlisations about the 1710 engine  it really is not as simple as people want it to be 

 

Cheers, Dakpilot 

[354thFG_Drewm3i-VR]

2 hours ago, Dakpilot said:

People keep quoting things that simply do not apply to the P-40E-1  of 1941 which arrived in time for Battle of Moscow as modelled and represented in 'our' P-40. 

 

Nothing wrong with wanting a later model... but there has been so much disinformation, whataboutisms, and generlisations about the 1710 engine  it really is not as simple as people want it to be 

 

Cheers, Dakpilot 

Your rebuttal is nothing but vacuous rhetoric. We are talking about the 1710-39 engine with 8:8:1 blower ratio optimized for lower altitudes found in the p-40e-1 that ran on 100/130 octane. And elsewhere I amd others have acknowledged that the overboosting up to and over 70" occurred only on 130 octane fuel, which could be an in-game mod that we have access to. 

[Aurora_Stealth]

My impression is that there does need to be some kind of planned development in future for a new engine overheating mechanic - the current system affects certain aircraft disproportionately in terms of their relative performance. Or at least that's how it seems.

 

Problem is... that sounds like a very complex mechanic to research and pull off accurately and it wouldn't just be the P-40 affected. This would then have to consider many different elements, including injection systems such as methanol water etc that create cooling effect for some aircraft; how efficient and large radiator designs were and one for the oil and one for water etc. This on top of how open the radiator flap is, and ambient temperature outside. Then we beg the question... engines overheat faster in a climb with reduced airflow - so how do you simulate all that lol - apply another factor based on AoA I guess.

 

Ideally some calculated system factor or temperature coefficient applied to each aircraft configuration that can simulate relatively each engine and associated radiator system's overheating speed would be something I'd like to see.

 

At least that way we could get a variable range of engine overheating responses while still potentially operating at higher potential boost pressures... you pay with faster overheating, especially in a climb and may result in knocking and then a failure or degraded engine power. I think that's broadly what I've heard a few people on the forum mention before.

Edited January 18, 2022 by Aurora_Stealth

[EduardoMCfly]

25 minutes ago, Aurora_Stealth said:

My impression is that there does need to be some kind of planned development in future for a new engine overheating mechanic - the current system affects certain aircraft disproportionately in terms of their relative performance. Or at least that's how it seems.

 

Problem is... that sounds like a very complex mechanic to research and pull off accurately and it wouldn't just be the P-40 affected. This would then have to consider many different elements, including injection systems such as methanol water etc that create cooling effect for some aircraft; how efficient and large radiator designs were and one for the oil and one for water etc. This on top of how open the radiator flap is, and ambient temperature outside. Then we beg the question... engines overheat faster in a climb with reduced airflow - so how do you simulate all that lol - apply another factor based on AoA I guess.

 

Ideally some calculated system factor or temperature coefficient applied to each aircraft configuration that can simulate relatively each engine and associated radiator system's overheating speed would be something I'd like to see.

 

At least that way we could get a variable range of engine overheating responses while still potentially operating at higher potential boost pressures... you pay with faster overheating, especially in a climb and may result in knocking and then a failure or degraded engine power. I think that's broadly what I've heard a few people on the forum mention before.

This.

[Dakpilot]

4 hours ago, -332FG-drewm3i-VR said:

Your rebuttal is nothing but vacuous rhetoric. We are talking about the 1710-39 engine with 8:8:1 blower ratio optimized for lower altitudes found in the p-40e-1 that ran on 100/130 octane. And elsewhere I amd others have acknowledged that the overboosting up to and over 70" occurred only on 130 octane fuel, which could be an in-game mod that we have access to. 

 

Not as simple.. there were later 3 types of crankshaft used, new improved  design of crankcase casting, new inlet manifold that helped with detonation in  certain cylinders and many other changes, insisting that a V-1710 of 1941 can reliably make +1700hp is like wanting a 1941 spitfire to have the same power available as a late 1944 one because they are basically the same engine, which they are - but with a few years of development thrown in, 

As I have said repeatedly what people really want are later versions of P-40, most of the even late improved - 39 engines had been replaced by newer -73 etc. versions by the time of the famous (nearly 1943) memo. 

 

Dev's have said that a rethink of how detonation is modelled is on the cards, hopefully when the fuel systems revamp is done it will be next

 

Cheers, Dakpilot 

[354thFG_Drewm3i-VR]

11 minutes ago, Dakpilot said:

 

Not as simple.. there were later 3 types of crankshaft used, new improved  design of crankcase casting, new inlet manifold that helped with detonation in  certain cylinders and many other changes, insisting that a V-1710 of 1941 can reliably make +1700hp is like wanting a 1941 spitfire to have the same power available as a late 1944 one because they are basically the same engine, which they are - but with a few years of development thrown in, 

As I have said repeatedly what people really want are later versions of P-40, most of the even late improved - 39 engines had been replaced by newer -73 etc. versions by the time of the famous (nearly 1943) memo. 

 

Dev's have said that a rethink of how detonation is modelled is on the cards, hopefully when the fuel systems revamp is done it will be next

 

Cheers, Dakpilot 

This is fair and valid and I do not dispute what you're saying when you lay it out like this. Still, I do think the evidence available points to the version of the Allison we have (even with the problematic reduction gear) being able to sustain much higher boost than we can in game, as well as sustain "combat power" of ~45" basically indefinitely as long as there is adequate cooling.

[Voyager]

2 hours ago, Dakpilot said:

 

Not as simple.. there were later 3 types of crankshaft used, new improved  design of crankcase casting, new inlet manifold that helped with detonation in  certain cylinders and many other changes, insisting that a V-1710 of 1941 can reliably make +1700hp is like wanting a 1941 spitfire to have the same power available as a late 1944 one because they are basically the same engine, which they are - but with a few years of development thrown in, 

As I have said repeatedly what people really want are later versions of P-40, most of the even late improved - 39 engines had been replaced by newer -73 etc. versions by the time of the famous (nearly 1943) memo. 

 

Dev's have said that a rethink of how detonation is modelled is on the cards, hopefully when the fuel systems revamp is done it will be next

 

Cheers, Dakpilot 

 

You also need to remember, engine design knowledge was far more limited at the time, so there's no guarantee that those were necessary or even valuable changes to improve reliability to run those engines at those limits, merely that the designers believed it to be so based on contemporary knowledge. 

 

Recall the test stand R-2800 that was run at R-4360 power levels. I seem to recall that was even a B engine, not a C core. Yet it did not fail, and the engineer only stopped the test because he did not have a good idea when it might. It was simply a complete unknown. 

 

Then turn around and compare the power density modern engines run at, and high performance automotive engines are capable of running at twice the power density or more of the most advanced WWII engines, without necessarily better materials. Part of that is simply a better understanding of what materials really can handle. Part of that is more consistent production standards so you have lower defect rates. Part of that is simple things like oil strainers that won't let bb-sized pellets get into the working parts. 

 

Basically, there is a lot of "we just don't know" in both directions. It does not go only one way. 

[Dennis_Nedry]

40 minutes ago, Voyager said:

 

You also need to remember, engine design knowledge was far more limited at the time, so there's no guarantee that those were necessary or even valuable changes to improve reliability to run those engines at those limits, merely that the designers believed it to be so based on contemporary knowledge. 

 

Recall the test stand R-2800 that was run at R-4360 power levels. I seem to recall that was even a B engine, not a C core. Yet it did not fail, and the engineer only stopped the test because he did not have a good idea when it might. It was simply a complete unknown. 

 

Then turn around and compare the power density modern engines run at, and high performance automotive engines are capable of running at twice the power density or more of the most advanced WWII engines, without necessarily better materials. Part of that is simply a better understanding of what materials really can handle. Part of that is more consistent production standards so you have lower defect rates. Part of that is simple things like oil strainers that won't let bb-sized pellets get into the working parts. 

 

Basically, there is a lot of "we just don't know" in both directions. It does not go only one way. 

I don’t think it’s accurate to say that engine design knowledge was far more limited.  Modern engines still run into design issues and sometimes they are never fully resolved.  The basics of the ICE are still the same.
 

Allison’s were tough, well designed engines but our engine timers don’t reflect that unfortunately.  Manuals are always on the conservative side especially when it comes to the US military.  Even to this day.
 

 

Edited January 18, 2022 by Dennis_Nedry

[SCG_Wulfe]

People might not like this due to the unknowable potential, but what if the hard timers were replaced by a soft timer system?

 

In this system, they would keep the timers and limits as they currently stand based on the service manual. However, once exceeded, a dice roll would be performed every 30 seconds. Every 30 seconds it would roll with say a 2-5% chance of engine failure. The odds of failure could be open to discussion, but I would suggest very low odds of failure that would not be overly punitive and would allow pilots to take small risks to push past the service manual... knowing that it could lead to a very small chance they damage their engine.

 

Even if the engine timers ceased to exist, I know many of us fly at very reasonable engine settings to conserve fuel when flying realistic sorties on any of the major servers. 

Edited January 18, 2022 by SCG_Wulfe

[Dennis_Nedry]

17 minutes ago, SCG_Wulfe said:

People might not like this due to the unknowable potential, but what if the hard timers were replaced by a soft timer system?

 

In this system, they would keep the timers and limits as they currently stand based on the service manual. However, once exceeded, a dice roll would be performed every 30 seconds. Every 30 seconds it would roll with say a 2-5% chance of engine failure. The odds of failure could be open to discussion, but I would suggest very low odds of failure that would not be overly punitive and would allow pilots to take small risks to push past the service manual... knowing that it could lead to a very small chance they damage their engine.

 

Even if the engine timers ceased to exist, I know many of us fly at very reasonable engine settings to conserve fuel when flying realistic sorties on any of the major servers. 

I don’t have a problem with hard limits I just think they need to be relaxed for a number of aircraft.  For example the P-47 should be able to use its entire WEP in one go and have a longer combat time.  The biggest issue for these engines should be overheating and then blowing up not a sudden blow up after a hard timer.

[EduardoMCfly]

1 hour ago, Dennis_Nedry said:

I don’t think it’s accurate to say that engine design knowledge was far more limited.  Modern engines still run into design issues and sometimes they are never fully resolved.  The basics of the ICE are still the same.
 

Allison’s were tough, well designed engines but our engine timers don’t reflect that unfortunately.  Manuals are always on the conservative side especially when it comes to the US military.  Even to this day.
 

 

That's why we need an overhaul!  

 

40 minutes ago, Dennis_Nedry said:

I don’t have a problem with hard limits I just think they need to be relaxed for a number of aircraft.  For example the P-47 should be able to use its entire WEP in one go and have a longer combat time.  The biggest issue for these engines should be overheating and then blowing up not a sudden blow up after a hard timer.

Also this.

[CUJO_1970]

2 hours ago, Voyager said:

You also need to remember, engine design knowledge was far more limited at the time, so there's no guarantee that those were necessary or even valuable changes to improve reliability to run those engines at those limits, merely that the designers believed it to be so based on contemporary knowledge.

 

[twilson37]

I think the issue with the hard timer limit is a tricky one for the developers. In reality engine failures occur at varying times after damage has occurred.  A plane may be flown outside its limits for 2 hours without an issue and then the engine packs it up the next day while cruising at 10,000 feet or on takeoff.  Furthermore an aircraft's performance degrades over time.  In game we fly brand new aircraft with each mission. If the designers were to take on the massive tasks of somehow incorporating this into the game I am sure a good portion of the community would be up in arms about how their 100 kill ace in career mode fell out of the sky when his engine packed up (insert Marseille joke here).

 

I think the P-40 falls victim to the hard timer more than any other aircraft because of the conservative nature of the flight data available for the aircraft.  The team has decided that anecdotal evidence or individual stories of planes being flown well beyond these limits is not enough to override the published flight data and understandably so as making major changes to the P-40 may open a can of worms where every other aircraft flight performance is up for debate.

[Voyager]

14 minutes ago, CUJO_1970 said:

 

 

Have you actually done hardware testing before? Once saw a system take around 3x the design load by accident. Shut a program down for six months while they tried to figure out if not had been damaged. 

 

Turns out it wasn't, but if you'd asked any engineer before that if it would survive and be fine, they'd tell you no. And, if it had not been a very expensive price of hardware, they would have simply thrown the whole thing out and started over. 

 

Just because it is listed on a piece of paper or produced by a model does not make it true. And just because a design should do something doesn't mean that it will. 

[CountZero]

47 minutes ago, twilson37 said:

I think the issue with the hard timer limit is a tricky one for the developers. In reality engine failures occur at varying times after damage has occurred.  A plane may be flown outside its limits for 2 hours without an issue and then the engine packs it up the next day while cruising at 10,000 feet or on takeoff.  Furthermore an aircraft's performance degrades over time.  In game we fly brand new aircraft with each mission. If the designers were to take on the massive tasks of somehow incorporating this into the game I am sure a good portion of the community would be up in arms about how their 100 kill ace in career mode fell out of the sky when his engine packed up (insert Marseille joke here).

 

I think the P-40 falls victim to the hard timer more than any other aircraft because of the conservative nature of the flight data available for the aircraft.  The team has decided that anecdotal evidence or individual stories of planes being flown well beyond these limits is not enough to override the published flight data and understandably so as making major changes to the P-40 may open a can of worms where every other aircraft flight performance is up for debate.

Aircrafts we get are in perfect representation of it no mather what in reality happend, but their engine is suposed to be on its last minuts, so that aint right, make realisam option to turn off timers and let fuel amount and engine temp dictates how things go... easy and fast fix to problems. Undestructable realisam option shows that thats posible, just separate it into its own option just having engine timers off.

Edited January 18, 2022 by CountZero

[CUJO_1970]

8 minutes ago, Voyager said:

Have you actually done hardware testing before?

 

I'm pretty damn old, so yes probably before you could walk...but that's not the question.  It was this whopper that left me dumbfounded:

 

2 hours ago, Voyager said:

You also need to remember, engine design knowledge was far more limited at the time, so there's no guarantee that those were necessary or even valuable changes to improve reliability to run those engines at those limits, merely that the designers believed it to be so based on contemporary knowledge.

 

Their knowledge was in no way "limited".  It was enlightened. More so than at any time in history with these engines, easily on par and in many cases exceeding today's Formula One engine builders, who at times are just now "rediscovering" things aircraft engines of the '30s and '40s were already using.

 

You use the term "contemporary knowledge" like it's a bad thing...I'd like to see an engineer today handwrite an equation that takes two weeks to express high stress calculations on a crankshaft like they did then. They are the giants upon whose shoulders today's mouse clickers stand up on.

 

And yes, those Allison engineers did in fact make changes that worked that made those engines both stronger and more reliable.

 

[Voyager]

@CUJO_1970Are you seriously arguing they metalurgy and structural design have stood still since the 1940's? Yes, things have been lost, but much has also been gained since.

 

Do you legitimately believe that *any* of those giants would look down their nose at a near real time finite element analysis, or the ability to model dozens of structures before cutting the first piece?

 

Do you legitimately believe in the 1940's they had the ability to manage the crystal structure of forgings the way we can do today? 

 

Yes, many of them were brilliant engineers, but we have *eighty years* of engineering work that has happened since then. Don't pretend the world has stood still. And don't pretend they knew everything.

 

They certainly did not. No engineer does, and the good ones are keenly aware of it. 

Edited January 18, 2022 by Voyager
Clarity

[twilson37]

This debate reminds me of a project I worked on. My company was redesigning some parts on an aircraft whose design predated computer design and finite element modelling.  The platform had been flying for decades through multiple wars and one particular spot was starting causing an issue. When the system was brought up to modern standards in 3D models and FEM analysis the design had multiple hot spots and looked completely unsafe to fly and to meet modern specifications it would have to be completely scrapped, but then everyone took a step back and realized that it had been flying forever, been through combat, suffered battle damage and never had a major incident. In the end we added some material at spots that historically had issues and basically left it alone. These aircraft are still in service today.  I think the tools we have at our disposal in the aviation industry are fantastic and have allowed us to make dramatic leaps in aviation design, however they may done so at the sake of the intuition and ingenuity of our predecessors.

[354thFG_Drewm3i-VR]

2 hours ago, Voyager said:

@CUJO_1970Are you seriously arguing they metalurgy and structural design have stood still since the 1940's? Yes, things have been lost, but much has also been gained since.

 

Do you legitimately believe that *any* of those giants would look down their nose at a near real time finite element analysis, or the ability to model dozens of structures before cutting the first piece?

 

Do you legitimately believe in the 1940's they had the ability to manage the crystal structure of forgings the way we can do today? 

 

Yes, many of them were brilliant engineers, but we have *eighty years* of engineering work that has happened since then. Don't pretend the world has stood still. And don't pretend they knew everything.

 

They certainly did not. No engineer does, and the good ones are keenly aware of it. 

To this point (again, not necessarily agreeing or disagreeing with the veracity of everything here, but...), all one has to do to realize that modern engines are built to much tighter tolerances and therefore extract more power from similar designs by fine tuning things like fuel delivery, air/fuel mixtures, camshaft timing, etc., is to look at the compression ratios of various modern engines derived from older designs (i.e. look at a modern Chevy LS engine for example and compare its compression ratio to a SBC). In light of this, it is not surprising that certain engines like the Allison which had a reputation for being stout, simple, and robust could extract more power than conservatively estimated by engineers doing calculations largely by hand and based on trial and error. In the field, reliability when over boosting would come down to things like maintenance schedules and quality, fuel quality and detonation resistance, and whether or not the internal reciprocating components in any given engine are devoid of metallurgic defects, which is a big unknown.

[CUJO_1970]

2 hours ago, Voyager said:

@CUJO_1970Are you seriously arguing they metalurgy and structural design have stood still since the 1940's? Yes, things have been lost, but much has also been gained since.

 

Nobody knows more about those Allison engines than the original designers, that calculated, drafted, built and tested every single part on those motors.

 

As far as Allison's work on the motors being "no guarantee that those were necessary or even valuable changes to improve reliability to run those engines"...They were certainly necessary and they did in fact improve both the power and reliability (also range and endurance) of those engines. How could you possibly suggest those changes weren't necessary or valuable? Allison literally added 300hp to the motor while making it more reliable at the same time.

 

"merely that the designers believed it to be so based on contemporary knowledge" - Yes, their contemporary knowledge was in fact greater than anyone today has about their own engines.

 

[Voyager]

6 hours ago, CUJO_1970 said:

 

Nobody knows more about those Allison engines than the original designers, that calculated, drafted, built and tested every single part on those motors.

 

As far as Allison's work on the motors being "no guarantee that those were necessary or even valuable changes to improve reliability to run those engines"...They were certainly necessary and they did in fact improve both the power and reliability (also range and endurance) of those engines. How could you possibly suggest those changes weren't necessary or valuable? Allison literally added 300hp to the motor while making it more reliable at the same time.

 

"merely that the designers believed it to be so based on contemporary knowledge" - Yes, their contemporary knowledge was in fact greater than anyone today has about their own engines.

 

 

A cursory investigation of modern forced induction engines shows a power density of around 180 HP per liter on automotive gas. 

 

Running 150 Octane leaded, the Allison has, at best 60.

 

I really don't think you are appreciating the limitations of test and verification in an environment where every test needs must risk hardware destruction, nor the amount of test data that has been gathered in the subsequent decades that simply was not, and could not have been available to the designers of the day. 

[SCG_Wulfe]

22 hours ago, Dennis_Nedry said:

I don’t have a problem with hard limits I just think they need to be relaxed for a number of aircraft.  For example the P-47 should be able to use its entire WEP in one go and have a longer combat time.  The biggest issue for these engines should be overheating and then blowing up not a sudden blow up after a hard timer.

 

The problem with this approach is that it is not a methodical or perceivably fair approach. It would be entirely up to popular consensus/the loudest voices in the room as to what aircraft should have their limits "relaxed". Ultimately it would lead to a never ending chorus of voices who believe they have been wronged/the game has been unbalanced. 

 

I truly think there are three good potential solutions. One, leave it as is... at least there is a baseline to make the decisions on (the service manuals). Two, remove/make an option to remove the timers completely. 

 

Or number three as I outlined, make it so that the timers are soft limits where once breached, "a dice roll would be performed every 30 seconds. Every 30 seconds it would roll with say a 2-5% chance of engine failure. The odds of failure could be open to discussion, but I would suggest very low odds of failure that would not be overly punitive and would allow pilots to take small risks to push past the service manual... knowing that it could lead to a very small chance they damage their engine."

 

To clarify, hard limits where we know engines had very high likelihood of instant failure once passed (over-rev etc.) should remain as is.