Engine damage

[PRB]

Some planes, like dcc’s P-38Ls, have engine damage “built-in” to them, such that operating above certain MP levels for more than a certain time causes engine failure. Is this “feature” part of the air file? If so, can it be added to an existing plane by adding the required data to the air file? Would it be the same for FS9 and FSX? Does FSX add more realistic options in this area?

[Moses03]

I was wondering this very same thing. Would be a great way to handicap race events.

Moses

[fliger747]

Haven't had much luck with the detonation levels settings so far. A number of planes have had engine damage parameters, including the Stearman's, but this is as far as I know a gauge addon. For the new DC2 we have a gauge addon for engine fire which is related to CHT. For CFS2 there was "reality x", which accomplished this feat. Perhaps DCC will clue us in on his approach.

T.

[Tako_Kichi]

A2A's Accu-Sim technology has been modelling exactly this feature for a while now but only for FSX Sp.2/Accel of course.

I know the Acceleration add-on added the capability for engine damage for the default P-51 racers but I don't know how anyone got engine damage working in FS9.

[teson1]

...engine damage “built-in” to them, such that operating above certain MP levels for more than a certain time causes engine failure.

Shouldn't this be very easy, almost trivial , with a gauge?
All it would have to do is read MP setting, compare it to a Max continuous Mp setpoint, and start a countdown timer if Max continuous is exceeded; If time is up, an engine failure is generated.
And if user could enter the setpoint MP via a separate panel or gauge this gauge could easily be used on different planes.
The failure logic could also easily be made more realistic.

Just an idea, after browsing through the gauge&panel sdk.

I'm just getting interested into this engine damage stuff, and how the engines can be made to perform more realistically, so would appreciate feedback if this would work in principle.

On the other hand, I don't know anything about gauge programming or xml at all, so I may have completely misunderstood.

But if this would work in principle, I may even give it a go if you give me a few months time .

[Moses03]

Gunter-

Is this your work? This looks real interesting.


FS2004 (ACOF) - FS2004 Panels FS2004 RealEngine
[ Download | View ]
Name: realenginev03.zip Size: 317,888 Date: 10-07-2009
FS2004 RealEngine v03. RealEngine is a gauge for piston engine aircraft that generates an engine failure if the engine is run under excessive operating conditions (MP and/or RPM) for too long. By Gunter Teson1.

[teson1]

Jep.
Finally it was not as trivial as I thought, or, the code was, but the implementation not. :d
I think it took me 6 hours of swea(t/r)ing till I got the engine to fail the first time. And that were maybe 15 lines of code... Count in a further 10 hours or so to polish things...
But it didn't take me months either... and I'm pretty happy with my first gauge.
Interesting experience learning xml, and in particular debugging. I think I had every error possible, from using no/wrong/misspelt units to missing spaces to syntax that changes between string and other formats, ect... My kids learnt some new words, I can tell you.

Hope you like it, and feedback on any problems is welcome.

[Dangerousdave26]

I down loaded it but did not have the chance to test it yet.

Here are some quick questions on how it works.

Does the timer reset?

Example I run the plane at 60 mp for 3 minutes when the continuous MP is 50.

I then switch back to 50 or less MP. 10 minutes later I power up to 60 MP again.

Does the timer restart or is it cumulative?

Can you do the same for Jet engines based on N1 RPM?

[teson1]

Hi Dave,

Does the timer reset?

"Damage", or rather strain, to the engine is cumulative.

My view was that this is more close to POH recommendations which sometimes state an absolute time limit, like 5 minutes at TO power, and would discourage exceeding recommended operating procedures; I wanted to make the damage model severe, so that RPM and MP have to be really closely watched.
However, the limitations can be set any way one wishes, and if needed the accumulation of damage can be interrupted, and restarted, by the "enable/disable" button.
Furthermore, the damage, and a failed engine, can be reset with the "reset" button. Also, that Button can be plan B if you don't feel like a dead stick landing after an engine failure.

Can you do the same for Jet engines based on N1 RPM?

Nice idea. I'm not at all into jets, but that should be pretty easy, just have to swap a few variables.
Also could set a time limit of a few seconds on excessive TIT.

Why is it, that as soon as you have released something that seems halfway ok, new ideas pop up? Had some thoughts yesterday evening as well.

[fliger747]

For most jet engines, temperature is more important than RPM. The most critical times being startup and takeoff/acceleration. On takeoff on a hot day you might not even be able to reach the N1/N2 limits, but certainly might reach the temp limits. Typically jet engines might not fail right then, but at some other inconvenient time......

For many high performance piston engines (R2800 for example) the things most likely to cause immediate failure are detonation: which practically worked out to be related to the intake carb temperature, so was less of a problem with intercoolers, cool days and higher altitude. This given a particular RPM/MP/BMEP combination; and hight CHT, causing a breakdown of cylinder lubrication and thermal stress to the cylinders. A rapid increase (due to lack of warming up the engine) in CHT could also cause the aluminum pistons to expand more rapidly than the steel cylinder bodies.... with ummmm unfortunate results....

In a certain upcoming (soon...) vintage transport aircraft, engine issues are linked to CHT, which will rise to an unacceptable value in 5-10 mins if power is not managed....

Cheers: T.

[Dangerousdave26]

For most jet engines, temperature is more important than RPM. The most critical times being startup and takeoff/acceleration. On takeoff on a hot day you might not even be able to reach the N1/N2 limits, but certainly might reach the temp limits. Typically jet engines might not fail right then, but at some other inconvenient time......

HHmmm...

Thats disappointing Tom but important to know. The issue becomes did the modeler acuratly model N1 verses ambiant air temp etc. If they did not then the gauge is worthless on some models.

Good to know though in our quest to impliment more accurate flight management.

One other thing...

Teson1 your not even close to done with this gauge. We have some additions you could make.

Look for a PM as we finish testing.

Dave

[teson1]

Teson1 your not even close to done with this gauge.

LOL You have some plans for me. :d

In fact I was planning to work further on this, and have some ideas. No problem to include whatever you want (within my limited programming knowledge of course).

However, I also have no problem at all to make a team effort out of this, or to completely hand over. After all, I'm sure some of you have 100x the experience I have with gauge development (litterally - in view that I have only about a week...) and engine/flight dynamics. And have included such failure stuff into planes for a long time. And the code really is no rocket science so far...

I'll watch the PM. We can discuss there.

[stansdds]

Ok, I tried this out. I used it on the Alpha Bleu Ceil F4U-7. I've set mine up as a modern restored aircraft equipped with a P&W R-2800-CB16 engine. I plugged in the maximum MAP, RPM and HP values as stated by the FAA into the engine section of the aircraft cfg. I plugged in the maximum continuous and 5 minute maximum MAP and RPM values as stated by the FAA into this guage. Now it seems I really need to pay attention to my flying. I have this engine set up without ADI, so advancing the throttle to maximum will exceed the 5 minute dry maximum ratings. Guess what? I exceeded the dry rating and suffered an engine failure shortly after leaving the ground. Yep, no more mindlessly jamming the throttle forward, now I have to actually watch the MAP gauge and tachometer.

By the way, anyone know how much it costs to replace a P&W R-2800-CB16 these days?

[fliger747]

CB 16's aren't too bad as it is/was a civillian engine made in rather copious numbers for the DC6 etc... could probably set you up with one.... O'le Cliffie Evererts still runs DC 6's here in Alaska powered by them and NAC has a whole field of mothballed 6's in Fairbanks....

Cheers; T

[hairyspin]

anyone know how much it costs to replace a P&W R-2800-CB16 these days?

If sir has to ask, sir cannot afford!

[stansdds]

If sir has to ask, sir cannot afford!

Of that, I am certain. Thank goodness flight simming does not require that kind of money.

[fliger747]

A further note on Jet engines. Before the advent of electronic fuel controls, the fuel control units were purely a maze of pressure and RPM sensors all interconnected by a forest or pushrods and levers. Today, as mechanical backup is still needed, that stuff still exists, but primary control is electronic. The early systems were not able to control the fuel via temperature. Only RPM could be regulated and limited. Moderns systems do provide overtemperature protection both at start and in flight phases.

In the 747-400 it is possible to turn off the EEC (electronic engine controls) and overboost the engines.......

Cheers: T.

[Wozza]

Hi All
Very interesting discussion
Im wondering if anybody knows the formula for working out an normally aspirated engine max possible MP at sea level.The reason ask is most info I can find normally give's the max permissible MP
Thanks
Wozza

[teson1]

For a normally aspirated engine (no turbo- or supercharger), the maximum possible manifold pressure is the ambient pressure. In fact, with the engine not running, the MP gauge should indicate ambient pressure.

That's 29.92 in Hg at sea level for standard conditions.
Of course, depending on weather, there can be a deviation from this value, say 29.3 - 30.5 in Hg (= altimeter setting).

Ambient pressure decreases by about 1 in Hg each 1000 ft.
E.g. standard conditions:
0 ft 29.92 in Hg
1000 ft 28.9
5000 ft 24.9
10000 ft 20.6

With the engine running, the maximum possible MP will be a little lower, as the cylinders are "sucking", and the air flow is somewhat throttled by the throttle plate and the intake.
I don't think there is an easy equation for this.

[fliger747]

I have seen 31+ inches (atmospheric pressure) at SL during very a very strong high pressure event in Alaska in the Winter. As noted above there are pressure losses in the induction system. I don't remember the factory MP limits for normaly aspirated limits, and indeed there may not be any as many of these engines are available in turbocharge models. Because of the extra disturbance in a blown induction system, it will take a higher MP to produce the same power rating that a non blown engine will have. Another big factor is density altitude, and for many engines, overboosting could happen at very cold temperatures, say -40C/F

Cheers: T

[teson1]

FWIW
I've worked a little more on the gauge (see .zip).
Current one allows inclusion of a climb setting with extended time-to-fail.
If two settings are the same, the less severe will be used (e.g. Climb RPM=TO RPM=2700 RPM -> 60 min allowed at 2700 RPM)

Just drop the .xml file into the gauges/RealEngine or panel/RealEngine folder.

Add/change the entry in panel.cfg to

[Window Titles]
...
WindowYY=RealEngine

[WindowYY]
position=3
size_mm=200,180
gauge00=RealEngine!RealEngine - MP RPM Limitations v04, 0,1

Note you have to pull up the gauge (Menu View-Control Panel-RealEngine) before it becomes active.

All variables are adjustable either by clickspots or in the .xml file.

Also see the manual for v3:
http://www.flightsim.com/file.php?cm=SEARCH1&fsec=73&fname=realenginev03.zi p

I'm currently working on modules for
- Flap/gear failure due to exceeding Vf/Vl speeds
- Plug fouling due to extended idling
- Engine running rough/damage if mixture is leaned too much

Gunter

[fliger747]

Glad to see you working on such accessories! please not for most aircraft that max gear speeds are promulgated on (1) aerodynamic loads for the gear doors (2) for small planes available hyd pressure to engage the downlocks. In the case of the 747, gear extended limit is M.82, however M1.0 has been exceeded in the "field" without damage to the gear itself.....

Fs tends to have the aircraft or component explode if a "limit" is exceeded. The 747 has a certified cruise limit of M.92, but I know that it has been cruised across the pacific at M.96 and flight tested to M.998. "Limits" apply over a whole range and assure certain load and upset parameters can be met. Execeeding these limits reduce the available size of the envelope.

RPM: FS tends to emphasize this in the evaluation of CHT. RPM is hard on an engine and with corresponding MP builds CHT and can cause lubrication failure and resultant connecting rod/piston "problems". Without high or low MP, high RPM is merely inefficcent if not required. Some engines such as the R 2800 are more tollerant of over MP than over RPM, such as in a dive. Lots of ways to puke an engine.

Cheers: T

[fliger747]

I do like the rough idle and also the over lean parameters. One of the weak spots in FS engine parameters is CHT, which seems to be affected primarally by RPM, a little less by airspeed and somewhat by cowl flap position. To see where this is problematic, reduce power at a set RPM and CHT will climb due to the reduced airflow. Take it at an extreme position to the CHT limit, plugging along at low speed and low power.... Then firewall it and CHT will drop as speed increases. A gauge that would be useful would tie EGT more closely with RPM to generate a more realistic figure.

Cheers: T.

[teson1]

Hi Tom,
thanks for your input!
I can need all the help I can get to understand under what conditions and how the components on the planes are failing, and what effects that has! No experience with real planes here. Input highly appreciated!

Currently I'm taking a very pragmatic approach - if the POH says don't do it, the engine will fail, or something else unwelcome, will happen if you do... ... with very simple logic.

So I'm far from creating a parallel aircraft model with Otto cycle and all...

However, that project is on slow burner for the time being. With the MacRobertson race going on that is taking up all my available limited sim time . Like there's this more or less nice competion by kids time, darling time, job time, friends time, do stuff time, ect...
Also, I had rushed development before the event as I hoped to use the modules in the race. But Warwick Carter's Gee Bee I'm flying now already has such great damage modeling, so no need there.

I'll get back to it after MacRobertson is over.
The flap/gear module is almost alpha, but I think I'll need some advice when I have something ready.
Maybe it's completely unrealistic, and I have added some sound effects with Doug Dawson's sound gauge, but have no idea if the sounds are even remotely similar to what one would hear (if anything!) in a real case. (also love A2A accusim's approach of assymmetric flap failure, but don't know whether I should implement their idea).
The others modules are still in design stage.

I'd love do discuss this more when MacRobertson is over and I can devote some more time!

Thanks.

Gunter

[stansdds]

All I have to say is.. and...