Aircraft cfg line: Detonation_onset=xx sets MAP failures

[guitar0633]

So continuing my search for planes with engine and torque failures because of the desire for more reality I have run upon this great aircraft cfg line that goes under the [Piston Engine] header in the planes aircraft cfg Detonation_onset=xx XX is the number of the map gauge that you want engine failure to begin on that specific plane. For instance, I put this line in my old Aerosoft Beaver X plane cfg., Detonation_onset=38. Holding my map at 38 for a few minutes sure enough causes the engine to start to dog down and will eventually quit.

I have toyed with it on all my Carenado Piston planes and have come to the conclusion that a couple notches below the very top map pressure warning line is about right because it takes a few minutes for the effects to happen. The map gauge on the Beaver says red line at 40 I believe. So this is a great find for my Carenado piston planes and others too.

BUT, how many other lines like this are there? I would love to find one of these for torque on turboprop planes. Or one to set icing and such. Does anyone know of any others that can simply be installed in to a plane cfg file for more failures? I have checked out realengine but man that thing seems so complicated and may be just too far over my head to use. I also like the idea of no extra gauges needed with this simple line in the cfg, it just causes MAP failure and it is set and forget with no extra guages needed. So i would love to find out if there are any more simple lines like this that can be inserted in to a cfg.

Hope others can use and enjoy this simple line for piston planes that have no failures. I already put it in my Carenado Shrike and Baron as well as the Bonanza, Beaver X and my Duke B60 as well.

 

[guitar0633]

And I forgot a question. On some planes, small ones like the Cub and various others there is NO MAP gauge. I assume this is because these type engines use some different direct type prop or something? So will this line work on them when the only gauge is an RPM gauge? My question is, does the RPM gauge function as a map gauge as well in these planes? The cub goes up to around 2,200 RPM when cranked all the way up sitting on the rnwy, I am wondering in this line would work set at 22 or if the line would not get used. If there is no MAP aguge then FSX may not even have a reference for MAP and so would not be able to use it. Just wondering if it's possible and WHY some planes like the cub have no map gauge in real life and only an RPM gauge.

 

[IanP]

Most aircraft with fixed pitch props don't have MAP gauges, simply because power is set by RPM, not MAP. With a variable pitch prop, you need to differentiate between MAP and prop RPM as they are set individually for power settings.

Ian P.

 

[guitar0633]

Most aircraft with fixed pitch props don't have MAP gauges, simply because power is set by RPM, not MAP. With a variable pitch prop, you need to differentiate between MAP and prop RPM as they are set individually for power settings.

Ian P.

Makes sense, thanks for the info. I guess I will just try the line in one of those and see what happens.

 

[PhantomTweak]

Well, there is max_rated_rpm= 2700. , I am pretty sure that if you exceed this for sufficient time you will cause engine damage/failure.
I know that if the conditions are met, carb icing can cause problems. Also, if you set the parameter for manual mixture control, you will get problems if you don't keep up with proper mixture control.
There is a small add-on, Icing.zip, available at most libraries, that makes the icing in FSX much more realistic. You need to do a few small edits to a plane's .air file if they are not already present to get it to work correctly, but it does work, and very nicely too. I've purposely flown into heavy icing conditions, and sure enough, my wings iced, prop iced, and it quit flying entirely.

I'm sure there're are others I don't know about, but I do know those...
Pat☺

 

[warchild]

EEEYUP..

OK,, Please dont mess with detonation onset. More than likely the FDE engineer did several hours of work to find the correct Detonation limit for that engine. It's a fixed number for any given engine ( the R2800-65W has a detonation point of 63 Inches whereas the R2800-73 had a detonation point of 73 inches because it was constantly water fed. ). Manifold pressure is not pressure per se. Its more like a vacuum. The Higher the MP, the hotter the temp. The hotter the temp, the closer it gets to catastrophic failure.. If someone is looking for reality, changing this number wont give it too you..

Much more likely is the possibility that some yokel is going to experiment and put too heavy of a propellor on the front of the engine. The heavier the propeller the harder it is to slow it dowqn, and the easier it is to over speed it. Theres veritable tomes written on propeller theory and the negative effects that can happen from overspeeding.. Thats why most planes that have a variable propeller also have an rpm adjustment knob. Its up to the pilot to control the engine rpm during dives and take-offs/climbs..

There used to be a wonderful addon that let you adjust several parameters for failures tht gave a huge amount of reality., We were using it in the P-61 for a while but lost contact with the developer. I believe its still around as i just saw it mentioned the other day. Sadly, i dont remember the name of it, so, good luck..
Pam.

 

[guitar0633]

EEEYUP..

OK,, Please dont mess with detonation onset. More than likely the FDE engineer did several hours of work to find the correct Detonation limit for that engine. It's a fixed number for any given engine ( the R2800-65W has a detonation point of 63 Inches whereas the R2800-73 had a detonation point of 73 inches because it was constantly water fed. ). Manifold pressure is not pressure per se. Its more like a vacuum. The Higher the MP, the hotter the temp. The hotter the temp, the closer it gets to catastrophic failure.. If someone is looking for reality, changing this number wont give it too you..

Much more likely is the possibility that some yokel is going to experiment and put too heavy of a propellor on the front of the engine. The heavier the propeller the harder it is to slow it dowqn, and the easier it is to over speed it. Theres veritable tomes written on propeller theory and the negative effects that can happen from overspeeding.. Thats why most planes that have a variable propeller also have an rpm adjustment knob. Its up to the pilot to control the engine rpm during dives and take-offs/climbs..

There used to be a wonderful addon that let you adjust several parameters for failures tht gave a huge amount of reality., We were using it in the P-61 for a while but lost contact with the developer. I believe its still around as i just saw it mentioned the other day. Sadly, i dont remember the name of it, so, good luck..
Pam.

problem is that on planes like the Carenado Shrike, the Baever X and a ton of Alabeo is that I can cram the throttle control all the way and leave it for the entire trip and the engine never complains. So I would rather use this line and at least have to back off on the map some, that feels more realistic. In planes like my Alabeo Saratoga, the Seminole, pretty much all of them I can crank the prop and map full on and nothing ever happens to the engine.

So even if this isn't realistic I would rather experiment and at least have to pay a little attention to the power settings. Why is it that these planes never punish you yet planes like Manfred's C47 do? It seems to me that Alabeo, Carenado and other makers just aren't programming in any punishment for cranked map and rpm. Are you saying that in the real life shrike a pilot can crank the map and rpm to 100 percent and do entire flights like this with no engine damge or shutdown? If that is true then I very well may stop using this.
The

 

[magoo]

RealEngine v1.4

A very good simulation of multiple system limitations & failures. It's a bit involved to set up at first, some learning is required, but you don't have to be a genius or a Jedi to figure it out.

Download here:

http://www.sim-outhouse.com/sohforums/local_links.php?catid=117&linkid=14627

Discussion here:

http://www.sim-outhouse.com/sohforums/showthread.php/38756-Real-Engine-1-1

Discussion Avsim:

https://www.avsim.com/forums/topic/...-realistic-aircraft-limitations-and-failures/

 

[warchild]

RealEngine v1.4

A very good simulation of multiple system limitations & failures. It's a bit involved to set up at first, some learning is required, but you don't have to be a genius or a Jedi to figure it out.

Download here:

http://www.sim-outhouse.com/sohforums/local_links.php?catid=117&linkid=14627

Discussion here:

http://www.sim-outhouse.com/sohforums/showthread.php/38756-Real-Engine-1-1

Discussion Avsim:

https://www.avsim.com/forums/topic/...-realistic-aircraft-limitations-and-failures/

THATS the one.. Thank you Sir..

 

[Mike71]

Let's not get too confused about detonation (I think it should be "pre-detonation") In any piston engine.

In a normally aspirated piston i.e. no supercharger/turbocharger, you get pre-detonation or "knocking" from either low fuel grade, bad ignition timing or too high cylinder head temperatures. That is why us old guys were always tinkering with a '56 Ford and the distributor position. Pre-ignition essentially means the fuel is igniting too early, usually on the compression stroke of the piston before it hits top dead center and is ready to be ignited.

The fuel can actually ignite by an overly hot engine at high compression, before the spark plug does the job - not good.

In a supercharged/turbocharged engine, fuel grade and cylinder head temp are critical in preventing pre-detonation, and why we see powerful engines in restored fighters/bombers being limited to a lower max MAP because they may have to use 100 octane vice 115/145 octane fuel. I have seen documentation where an USAAF P-51D was tested with a very high octane fuel (I thing around 160) and could pull 70"MAP before it started to start knocking - that is about 10" higher than the most powerful pistons I am aware of.

Cylinder head temps are not a big deal just because it is not good for the metal/seals in the engine, but will cause knocking at high power settings ,which wil leventually "blow a jug" as we say..

 

[magoo]

That is why us old guys were always tinkering with a '56 Ford and the distributor position.

I recall the rule with 292's was to grab the distributor and crank it around 'til the mill started to sing, and then back it off a bit.
In fact....that seemed to work with any engine from that period until I could scrape up the money to buy an exotic tool called a timing light......

.....Now days the young fellow next door tunes his Honda with a laptop computer.....and has no idea what a distributor is....at least....relative to internal combustion engines......

 

[Bjoern]

I don't understand the finger wagging regarding flight dynamics here. The description for detonation_onset reads "The manifold pressure that if reached or exceeded will lead to the engine detonating".
Save for making the engine go boom, it does absolutely nothing that alters general engine performance.
And before one needs to dig into the deepest depths of the web to scrape together enough data for a RealEngine profile, it's best to just plug this line into the aircraft.cfg and be done with it (if it isn't there). Quick and easy.

Here's a on overview of all aircraft.cfg parameters, by the way:
https://msdn.microsoft.com/en-us/library/cc526949.aspx

 

[Mike71]

I don't understand the finger wagging regarding flight dynamics here.

Agree, but the tech term should be "pre-detonation", caused by the fuel/air mixture being heated to ignition temperature due to the heat caused by the compression (i.e. MAP) being too high, along with possibly the CHT being too high and/or fuel grade too low, rather than ignition being caused by the spark plug and timing, at the right position in relation to the piston at top dead center (the manufacturers' spark retard or advance spec).