Engine Detonation

[R33GZ]

Reading a book at the moment that details an over revved engine surviving about an hour at maximum settings without detonating. The engine was so hot, that the nacelle or cowlings were glowing red, but it kept running and got them home. The aircraft was a C-119K Stinger flying night interdiction over the Ho Chi Minh trail in Laos when it had roughly half of its wing shot off by AAA and the pilot had to overspeed the engine to maintain 'level' flight due the asymmetric nature of the 'redesigned' wing.

 

The engines on the C-119K are the same as those used on the Goodyear F2G Corsair.

 

Is this proof that engine detonation timers can be tamed back a bit for Il2 Korea? or is this just a one in a million chance for an aircraft that really shouldn't have been able to fly at all. 

 

I dont really understand the mechanics of engine detonation. I suspect it is to do with too much pressure generated in the manifold and something has to give, so.... BOOOM!

 

If anyone is interested in the book, it is called, Magnet Ass and the Stone Cold Truck Killers. The crew were awarded the Mackay Trophy for their endeavor.

[BlitzPig_EL]

Detonation, is actually "pre-ignition", commonly called "spark knock" or pinging (pinking in the King's English).  It is normally caused by insufficient octane rating of fuel for the compression ratio of the engine, or "over boosting" in a forced induction (turbo or supercharger) engine, or improperly set ignition timing, or even an over heating condition brought on by any number of issues.  If the condition is allowed to continue it can result in burned or holed pistons, blown head gaskets, or other mechanical calamity.  The engine does not spontaneously explode, but it is rather a rapid, unscheduled disassembly that resembles an explosion because of the typically high rpm of the engine when it happens.

Edited Tuesday at 11:41 AM by BlitzPig_EL

[AndyJWest]

5 hours ago, R33GZ said:

...is this just a one in a million chance for an aircraft that really shouldn't have been able to fly at all... 

 

Don't know about one in a million, but yes, real-life mechanical failures are unpredictable. No two engines are going to react in exactly the same way when abused. Manufacturing tolerances, prior wear, adequacy of maintenance, etc are all going to factor in. You can't build an engine simulation failure model around anecdotes, so all you can do is look at statistical data if it exists, look at what the official limits were, and work from that. Should there be a random element to this, in a simulation? Maybe, if you want to be as realistic as possible, but people generally seem not to be too happy with that idea. 

[R33GZ]

8 hours ago, BlitzPig_EL said:

 a rapid, unscheduled disassembly that resembles an explosion

That is violently poetic, and makes sense. Thanks EL.

 

7 hours ago, AndyJWest said:

all you can do is look at statistical data if it exists, look at what the official limits were, and work from that

I guess what prompted me to post the anecdote, was firstly, the engine is from the same stable as those used on the P-47, F4U and A-1. It is not the same, but certainly from the same line of development.

 

Secondly, we currently have a limit of 5min(?) for max power on the P-47, at which time engine detonation occurs. I guess I am curious to know if the engine timers will be revisited in Il2:Korea. 

 

I think its fairly safe to say that 60min was a hail Mary scenario, but it does make wonder if that 5min could pushed out to say 10-15min? Maybe with a chance variable thrown in?

[AndyJWest]

51 minutes ago, R33GZ said:

I think its fairly safe to say that 60min was a hail Mary scenario, but it does make wonder if that 5min could pushed out to say 10-15min? Maybe with a chance variable thrown in?

 

Again, you can't build an engine model around anecdotes. How often has the same engine type failed with say just a minute of abuse? We don't know, and are unlikely to ever find out, for survivor bias reasons as much as anything else. As for what the developers are doing in IL-2 Korea, if they haven't already discussed it (I've not been following everything that closely), I'm sure they will.

 

(And please read again what BlitzPig_EL wrote above about 'detonation'. This is a specific technical term, AKA pre-ignition, and doesn't mean 'generic catastrophic engine failure', though pre-ignition is certainly one potential cause of failure . Failures can occur for all sorts of reasons when you push an engine too hard, and I doubt the IL-2 GB engine modelling is built around the premise that detonation is the only failure mode. They have to keep the model fairly simple, but they should be modelling the all-mode failure rate, not anything more specific)

[LukeFF]

Our latest video with Roman actually goes into what is planned for engine failure modes, for those who are wondering. 🙂

[Tonester]

i didnt know what a C119 was so i looked it up. Shorten the wings a bit and it looks like Thunderbird 2 🤣