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PRB
September 20th, 2009, 12:38
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
September 20th, 2009, 15:14
I was wondering this very same thing. Would be a great way to handicap race events.

Moses

fliger747
September 24th, 2009, 12:28
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
September 24th, 2009, 12:36
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
September 25th, 2009, 14:54
...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. :monkies:

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

Moses03
October 7th, 2009, 05:51
Gunter-

Is this your work? This looks real interesting.


FS2004 (ACOF) - FS2004 Panels FS2004 RealEngine
[ Download (http://www.flightsim.com/kdl.php?fid=139825) | View (http://www.flightsim.com/zview.php?cm=list&fid=139825) ]
Name: realenginev03.zip (http://www.flightsim.com/kdl.php?fid=139825) Size: 317,888 Date: 10-07-2009
http://www.flightsim.com/o/realenginev03.gif 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
October 7th, 2009, 06:16
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... :kilroy: 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. :jump:
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. :icon_lol:

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

Dangerousdave26
October 7th, 2009, 16:38
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
October 8th, 2009, 05:25
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? :rolleyes: Had some thoughts yesterday evening as well.

fliger747
October 8th, 2009, 15:38
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
October 8th, 2009, 18:35
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. :kilroy:

Look for a PM as we finish testing.

Dave

teson1
October 9th, 2009, 04:51
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
October 9th, 2009, 14:40
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. :applause:

By the way, anyone know how much it costs to replace a P&W R-2800-CB16 these days? :173go1:

fliger747
October 9th, 2009, 17:40
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
October 10th, 2009, 06:57
anyone know how much it costs to replace a P&W R-2800-CB16 these days? :173go1:

If sir has to ask, sir cannot afford! :icon_lol:

stansdds
October 10th, 2009, 13:39
If sir has to ask, sir cannot afford! :icon_lol:
Of that, I am certain. Thank goodness flight simming does not require that kind of money.

fliger747
October 10th, 2009, 16:29
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
October 15th, 2009, 03:57
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
October 15th, 2009, 14:56
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
October 15th, 2009, 15:48
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
October 15th, 2009, 16:29
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.zip (http://www.flightsim.com/file.php?cm=SEARCH1&fsec=73&fname=realenginev03.zip)

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
October 21st, 2009, 00:48
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
October 22nd, 2009, 07:17
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
October 22nd, 2009, 09:50
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... :engel016: ... 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 :icon_lol:. 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
October 22nd, 2009, 16:40
All I have to say is.. :jump: and... :applause:

fliger747
October 24th, 2009, 10:47
A pretty good way of modelling minor onset of engine difficulties could be through sound and (new idea) minor vibration modeled through the head movement possibilities in FSX. for those deaf and blind, further possibilities exist.....

Cheers; T

Wozza
October 25th, 2009, 05:45
But Warwick Carter's Gee Bee I'm flying now already has such great damage modeling, so no need there.



Gee thanks compared to your stuff the GeeBee is very basic.... :)

Ok for you all knowing ones...think this is on topic? :)
P&W R-1340-AN-1 single speed supercharger,what MP would I expect at sea level with the throttle to the wall,Ive read reports from current pilots about their take off procedures and notice it was said a few times that they used the max permissibly MP of 36 for take off but the throttle wasnt all the way to the wall.This got me thinking I can use the Accel engine damage to supplement some xml coding.Yeah I working on a Texan (prob the SNJ as carrier ops are fun ) Im concentrating more on the systems this time round...if FSX will let me..... curse you Msoft you won the first 2 rounds but I will not go quietly into the night :D
Thanks
Wozza

fliger747
October 25th, 2009, 09:38
Most of the various super/turbo charged GA type engines that I have flown have been like that. Fairly simple controls, a max listed MP, which however does allow you to keep pushing the throttle up (if required) till some critical altitude (perhaps 4000' or so) is reached where the max throttle movement will match the max permissible MP. Max climb MP would be available to a somewhat higher altitude.

The single most dangerous factor that can lead to quick and fatal engine destruction for large piston engines is detonation. Not always obvious as to what might cause detonation except high MP is the main ingredient. However high octane fuel, and use of ADI (water methanol) injection delay the onset. The temperature of the mixture prior to entering the cylinders is a factor. Intercoolers (and their proper use) as well as low outside temperatures help this out. High outside temps, bad fuel etc. are contributing factors.

Cheers: T

Wozza
October 26th, 2009, 23:31
Thanks Tom
At the mo I have the super charger set up to give me an full throttle MP of 36 at around 5.5k ft which then gives me a MP about 42ish at sea level,with a detonation_onset of 36.0 this will mean a long wait for complete engine damage with the built in accel damage model but will do as a start.I so wish we could plug into the default failure system via xml code,some of the effects are cool :)
Thanks
Wozza

fliger747
October 27th, 2009, 08:01
Indeed if it were possible to "supercharge" the detonation effect. Detonation can tear up an engine in even the short minute or so of a takeoff. The DC6 flight engineers have copious instrumentation which helps them a lot in engine managment. During the 1944 fighter conference the use of detonation detectors in fighters was discussed. The USN viewpoint was that such "gadgets" were prone to failure and error and might cause more problems via distraction.

One of the problems is that a particular episode might not blow a jug off, but cause problems later. Even cracking from over cooling from a rapid low throttle descent might not show up immediatly.

Failure is often a result of a multitude of previous sins....

Nice plane! T

teson1
October 27th, 2009, 12:41
Gee thanks compared to your stuff the GeeBee is very basic.... :)

Very kind of you, but completely off...
At least wait till I've delivered. :d
I really like your Gee Bee; I'll pull this up also after the race. Real fun to buzz around in it!
Gunter

stansdds
December 23rd, 2009, 02:59
:bump:

Don't want this falling off the radar.

teson1
December 24th, 2009, 12:26
LOL. No fear, not forgot.
Just still having too much fun with the London-Melbourne trip. Never mind the race part is over. Takes up all the available time.
(And progressed a little with the code nevertheless.)

stansdds
December 30th, 2009, 02:19
Excellent!

Brett_Henderson
February 27th, 2010, 08:51
I've been fascinated with this type of gauge(s) for years.. but never got around to working on it. I intended to have something ready for my last model (the Bonanza P35).

ANYway.. I'll throw some ideas in..

Has cumulative CUMULATIVE damage been pondered ? As in not just for that session, but so that abuse adds up flight after flight. We already know that FSX stores engine time. I believe it's a simple text file somewhere in the user's documents folders. You can see how it works on aircraft whose tachometers also display hours... which is most of them. This engine failure gauge could read/write to a similar text file keeping track of long-term, cumulative wear.

And in addition to MP and RPM.. throw in CHT abuse ?

teson1
March 11th, 2010, 09:48
Hi, I'm still here...
and on it. :wiggle:

I warned you in the beginning you'd have to give me a few months... :icon_lol:

With the RTW race over, I can focus more. And I think I'll also just leave my Bee Gee a little more time hangared in Java, before continuing on to Melbourne to finally finish that London-Melbourne *cough* race...

Actually, good news is I've progressed a lot on the modules in the mean time, most just need some more final testing.
I plan to release for beta testing soon (within the next few weeks... but don't hold your breath).

Modules finished and just needing final testing are:
- Engine damage - impact of MP, RPM, power, mixture, CHT, oil temperature
- Leaning - engine running rough with overrich or overlean mixture
- Spark plug fouling
- Gear and flaps failure due to overspeed

But don't get overexcited... you'll find that implementation and effects are pretty crude.
Really, these modules just have something _bad_ (not necesarily something realistic!) happen if limitations or recommendations of the POH are disregarded.
Goal is simply to enforce limitations are respected to the letter, as one would probably in real life.
Just wait till it's released.

Brett, CHT as a source, and indication, of engine damage was high on my wish list as well. Actually there's a simple module generating engine failure if CHT limitation is exceeded. However, from the testing I've done it seems that CHT (impact of power settings, cowl flaps, speed, temperature, ground operations, mixture ect on CHT) is poorly modeled in FS9. So the whole effect is kind of useless as CHT does not behave realistically. To have a halfway realistic damage effect due to CHT, I believe CHT has to be controlled from outside of FS. I have a lead on how to do that, but that's currently _way_ over my head... maybe later...

No cumulative wear. Not possible with XML AFAIK, and IMO the damage model is not fine enough to get something realistic out of it long term.

But thanks for bumping. A little reminder from time to time does help. :icon_lol:

Gunter

fliger747
March 11th, 2010, 10:57
Yup

CHT is about worthless in FS, we tried to tie engine damage in the FSX DC2 to it without much sucess as it is almost wholy dependent on RPM.....

Cheers: T

stansdds
March 13th, 2010, 04:09
Yes, I noticed in FS9 and in FSX (except for A2A's AccuSim), cylinder head temperature is directly linked to engine RPM. There must be a way around it, seems to me the 1% group that remade the flight models for CFS2 and CFS3 aircraft were able to implement cylinder head temperature based on other factors. I remember cooking the engine of the F4U-1A while trying to land. I don't know how they did it or if it was really accurate, but it was frustrating trying to keep that engine cool.

teson1
March 13th, 2010, 13:04
I believe for a single aircraft it's pretty easy to implement.
Just don't display A:RECIP ENG CYLINDER HEAD TEMPERATURE by the CHT gauge, but an L: variable.
This L: variable can be anything from FS CHT + an offset to a separate model of the physical effects that may affect CHT (power, cooling, damage ect ...).
I believe this is how it's done in Wozza's Gee Bee (btw, I'm an expert in cooking that engine...).
Of course this only works if implemented by the acft designer, or if the CHT gauge can be edited to display the L: variable.

fliger747
March 15th, 2010, 19:34
In one plane I was involved in we linked invisible cowl flaps to the mixture value, such that the stoichemetric value closed the cowl flaps fully and either side of peak opened them, to allow manual leaning of the mixture by watching CHT. However we wer still stuck with the direct RPM link, such that even on a low powered descent it was possible to overheat the engine which triggered a damage scenario.

I think the FS guys stuck with a simple fixed pitch model of developing CHT, using RPM/airspeed/cowl flap position to generate a value. A fairly useless set of assumptions for a constant speed prop.

Cheers: T

Brett_Henderson
March 19th, 2010, 13:27
I've had pretty good success with CHT (as it appears on the gauge)... You can go into the AIR file with something like AirEd, modify three factors. 1) The overal range 2) A multiplying factor 3) A cooling factor.

It's still weird though, because MP has the largest effect (which is realistic).. and RPMs are next (you can hold back CHT by pulling prop-rpm back).

Anyway... it's much better than stock, and the gauge number can be used for "cause".

Also.. remember that FSX allows for detonation damage. You can set it in aircraft.cfg file (MP where detonation begins)...

fliger747
March 19th, 2010, 20:00
Working presently with an airfile that has some engine damage scenarios based on CHT. Unrealistically the hardest palce to keep the engine from overheating is at low airspeed on approach with a realistically high RPM. So far I see very little effect of MP on the CHT.

The "cooling effect" seems to be primaraily related to airspeed.

The "scalar" is a multiplier which you can use as a fudge factor to achieve the correct CHT range.

Cheers: T

stansdds
March 20th, 2010, 03:17
Working presently with an airfile that has some engine damage scenarios based on CHT. Unrealistically the hardest palce to keep the engine from overheating is at low airspeed on approach with a realistically high RPM. So far I see very little effect of MP on the CHT.

The "cooling effect" seems to be primaraily related to airspeed.

The "scalar" is a multiplier which you can use as a fudge factor to achieve the correct CHT range.

Cheers: T
That's the exact thing that I experienced with the 1% flight models in CFS2. The engine would cook about the time I turned onto my final approach.

teson1
April 3rd, 2010, 15:02
:gameon:

Guess it's beta testing time, before uploading. No idea how to do that though, so I'm just posting RealEngine v0.5 here.

Could you check it out and report back with any problems, suggestions or comments.

I have the following questions in particular:

- Pls report any problems.

- Could somebody test it in FSX? Really no reason why it shouldn't work, but I don't have FSX.

- Any _gross_ errors in the Manual? The Operating recommendations are based on reputable references (main references cited), but I can always have understood/formulated something wrongly. (_gross_ please only, otherwise this will be like opening a can of worms. )

Otherwise I'm open to suggestions on how to improve.

RealEngine includes the following modules:

- Engine Power Limitations
Simulates damage (first roughness, then failure) to the engine if % power limitations are exceeded.

- Engine MP RPM Limitations
Simulates damage (first roughness, then failure) to the engine if MP or RPM limitations are exceeded.

- Mixture State
Engine runs rough if mixture is too lean or too rich.
Engine can be damaged if mixture is too lean at higher power. High power operations like take-off or climb require rich/full rich mixture to avoid damage to the engine due to overheating or detonation.

- Spark Plug Fouling
Simulates power loss due to spark plug fouling if engine is idled for too long. Do a proper run-up!

- Gear Overspeed Failure
Generates gear failure if gear speeds are exceeded.

- Flaps Overspeed Failure
Generates flaps failure if flaps speeds are exceeded.
Asymmetric failure of flaps is modelled.

- Cylinder Head Temperature (CHT) Limitations
Generates engine failure if CHT limitations are exceeded.

- Oil Temperature Limitations
Generates engine failure if oil temperature limitations are exceeded.

The modules can be individually activated/deactivated and fully tailored to individual preferences.
Manual included.

Cheers,

Gunter

MaddogK
April 4th, 2010, 06:18
Nice job, will test today.

fliger747
April 4th, 2010, 07:48
Looks quite interesting, will have to take a look.

Deciding what and how damages will be implimented is quite a task! For example FS tends to have a pass fail damage system. Fly over the VMO of an aircraft for 30 seconds and the plane explodes.... For trasnsport category aircraft, full load and manuver capabilities are usually available up to the stated limits. Above the certification limits lesser and generally not published load factors still exist. This can vary a lot, some BIZ jets and WWII fighters were famous for having very poor mach tuck limits, attributes that can be modeled into air file with some effort. A flight parameter that A2A left out of their otherwise nice P47.

Landing gear.... The IAS limit for extending the gear on the 747 is 275 kts IAS/M0.82. Once extended it rises to 320 Kts/M.85. The reason for this is the gear doors, most of which cycle (some stay open) and re-close. However, the gear has been extended above M1.0 sucessfully.... with damage to the doors. Some landing gear extends by free fall, in some of these cases, extending the gear above the limit speed may not allow it to fully extend and lock against the air loads, however it may or may not lock down (it probably will) after the airloads are reduced. The gear limit on the F4U was due to the gear doors for the tailwheel, the mains were able to be used as dive brakes and a seperate control was used to extend them without extending the TW. The Fairchild/Fokker F27 had what we called a drag brake, which was a seperate switch thta extended the main gear but not the nose gear and could be used up to the VMo of the aircraft!

I am sure that you have put a lot of thought into this! Especially looking forward to seeing how the engine parameters are implimented.

Cheers: T

teson1
April 4th, 2010, 10:44
To get this out of the way, and not to raise to many expectations. :kilroy:

Failures definitely don't happen as they would with a real plane, but are intended to occur exactly (or with a small safety margin) if limitations and operating recommendations stated in the POH are exceeded.

So RealEngine is not for those who want to push the planes to their physical limits, and have them fail realistically, or would like to know the real damage the plane would sustain. Would be nice, and I would be the first to agree, but I wouldn't be able to realistically simulate under what conditions a real plane would fail, nor did I intend to. This is no competition to Accusim... ;)

The effects are not necessarily very realistic either (but I would appreciate any advice how to make them closer to what one would observe in a real aircraft!).

However, RealEngine may help to fly according to POH.
For those leasurely GA pilots like me who tend to be a little heavy on the throttle, skip the run-up ect, as there's no real disadvantage doing so with most planes, it adds the fear of a failure if recommended operating procedures are disregarded.

Just to make the scope of the program clear.
Thanks in any way to have a look at it. :wavey:

Gunter

fliger747
April 4th, 2010, 17:48
Reading the manual, you spell out quite clearly the objectives and features. A very intillegent approach! That it can be customized for each aircraft is a very good method.

Good job! T

teson1
April 5th, 2010, 00:05
LOL :d
I knew I'd be in for a lot of heat if there was the slightest ambiguity.
:greenf:

MaddogK
April 5th, 2010, 11:43
Am already stripping 'race ready' A/C from those who'll get the realistic treatment.

Kudos for finishing the MacRobertson in 'roastable' the GeeBee, I wanted to use it, but realized it wouldn't stand a chance with that handicap system they devised. Ive used that realism gauge (from the GeeBee) in a couple other A/C for quite a while and am very happy with it, but yours looks to be alot more fun (challenging).

teson1
April 5th, 2010, 14:05
Who said I'd finished the McRobertson? :d
I just finished a flight from Surabaya over Bali island to Mataram in Indonesia. The Gee Bee had been hangared in Surabaya since december... Just no time with the RTWR, the gauge and other stuff. It felt so good to be going again... 7 legs to go to Melbourne...

MaddogK
April 5th, 2010, 14:27
Who said I'd finished the McRobertson? :d
I just finished a flight from Surabaya over Bali island to Mataram in Indonesia. The Gee Bee had been hangared in Surabaya since december... Just no time with the RTWR, the gauge and other stuff. It felt so good to be going again... 7 legs to go to Melbourne...

No worries, I'll prolly see you fly overhead any day now as I put down around there, and have been drinkin mai-tai's ever since.

sc7500
April 11th, 2010, 20:50
...By the way, anyone know how much it costs to replace a P&W R-2800-CB16 these days?...

Ask and Ye Shall Be Shocked.....

http://www.sunairparts.com/recipengines.htm

R-2800-CB16 0-Time $68,000.00

:: Gulp ! ::
SC
:kilroy:

teson1
April 21st, 2010, 02:07
Thanks to those who have downloaded and tested; I guess no news = good news. Seems everything works perfectly.

I'd really like to know whether it works at all in FSX before uploading though.
Did anybody try it at all in FSX? Or could do a quick test.

Thanks a lot.

Gunter

Brett_Henderson
April 21st, 2010, 04:44
Thanks to those who have downloaded and tested; I guess no news = good news. Seems everything works perfectly.

I'd really like to know whether it works at all in FSX before uploading though.
Did anybody try it at all in FSX? Or could do a quick test.

Thanks a lot.

Gunter

So far, so good, in FSX ..

This is a very impressive bit of work.. I'll report more as I keep testing ..

Quick question.. I'm going to try it in a twin. Will it only affect one engine ?

Brett_Henderson
April 21st, 2010, 08:39
Further report...

After tweaking the parameters to fit my Bonanza.. and tweaking the Bonanza's air-file for better numbers.. I'm really impressed with this add-on. Thanks for taking the time to create and share it.. !

Now I just gotta figure out how to get it to read/write from a data file, for flight-to-flight, cumulative abuse.

teson1
April 21st, 2010, 09:38
Hi Brett,
thanks for the feed-back!
Great to hear it works in FSX as well. :jump:

I'll wait a day or two if any further problems pop up, and upload then.

I think you've meanwhile found out it fails a single engine on twins. But I know you're up to date on your single engine failure drills.

Thanks.

Gunter

Brett_Henderson
April 21st, 2010, 09:45
I'm certain I can copy, rename and edit certain modules for twin-engine use... so I'm focusing on what it takes to read/write to a text file..

Thanks again for all your work :salute:

fliger747
April 21st, 2010, 10:54
Per cubic inch, the above mentioned R2800 CB 16 is a deal! About $3,700/cyl or $25/cu inch. My Super cub engine was $6,240/cylinder or $78 per cu inch.

Cheers: T

Brett_Henderson
April 22nd, 2010, 05:41
More reporting (this is a lot of fun).. :wavey:

I did as I alluded.. copied/renamed engine specific files.. edited them to relate to engine '2'.. added them to the panel.cfg.. and it works well (so far).

I don't use the status panel, now that I've refined the parameters (for a customized Carenado Seneca)(non-turbo-charged, 200hp Seneca I)..

I had already edited the air-file for more realistic gauge responses (namely CHT).. and made custom gauges (for non-turbo-charged MP/RPM)..

More testing is required.. but it's pretty much doing what I'd want.. FORCING me to fly realistically :jump:

Brett_Henderson
April 23rd, 2010, 04:25
More thoughts...

How about an XML document (cumulative_wear.xml) in the panel folder, that serves no purpose other than to store a number (cumulative wear).

Then, the XML files that keep track of wear per session, could also take the number from cumulative_wear.xml.. add to it when conditions warrant, and initiate a failure when IT reaches a certain value..

I.E. .. When CHT is exceded, not only does the session specific "count-down" begin.. a loop that retrieves 'cumulative wear', adds to it, compares it, and re-writes the XML file with the new value, so that the long-term wear is stored.

Aviator273
April 23rd, 2010, 09:16
I gave it a try with fsx and the default Cessna 172 now. This gauges are the greatest improvement for the aircrafts ever. Good work. The only think leading to a crash here is the flaps overspeed. Dunno if it was my mistake or not. Since there's another plane in my library using a sound-gauge with the same description I didn't want to overwrite the file and just left it besides. May it be possible that there's some conflikt due to the gauge beeing both in the gauge folder and the panel/realengine folder? If these files are different to each other so that it's just loading a completly wrong gauge from my gauge folder, may this lead to the problem?

Greetings.

teson1
April 23rd, 2010, 15:44
Brett,
good to hear that you could make the gauges do what you want.
Just one point you may want to look out for. If you want to follow two engines at the same time you may have to give some L: variables a unique name, otherwise the gauges for eng 1 and eng2 may use some of the same L: values to store data (overwrite), and probably only one engine will ever fail in that case.

I had actually considered to include damage to several engines for multiengine aircraft.
While that would have been quite easy, I shied away for the time being, for fear of (unavoidable) lengthy troubbleshooting sessions. I was addressing fundamental changes to working modules very carefully at that time. I feel XML is a bitch in penalising the slightest error in syntax...:blind: Maybe if ever for a v2.

And if you find a way to write and read from an ini file - that would be NICE!
Good luck, and let me know if you find a way.
With a C gauge it must be possible (to read at least - Doug Dawson's sound gauge does). But C is currently outside of my domain of expertise, or rather my domain at all...

Hi Aviator,
glad to hear you like it. Thanks.
AFAIK having Doug Dawson's sound gauge in the gauges and panel folder at the same time causes no conflict. AFAIK FS first looks in the panel folder for the gauge specified in the panel.cfg, and only if it does not find it there, in the gauge folder.
Also, Doug's dsd_xml_sound3.gau gauge is unchanged, so if you have installed the same version already, then you can also just delete the one in the panel.cfg.
The RealEngine specific file is actually dsd_xml_sound3_RealEngine_v05.ini, which defines the sound files to play, and has to be in the gauges folder to be found by dsd_xml_sound3.gau (as specified in the panel.cfg).

Pls report back if you have further problems with crashes due to the flaps failure or other modules. I may have to look into that. No idea off of my head how the XML gauges would cause a (computer or FS) crash. Thanks.

Regards.

Brett_Henderson
April 23rd, 2010, 16:05
I dowloaded Visual C++ .. will start playing with it... but I've got my hands full learning XML..

What I did literally; was to copy all the modules.. renamed them all RE2-XXXXXXXX.xml...deleted the status panel gauge, and gear/flap stuff.. added them to the panel.cfg .. .. and then changed every '1' reference, to a '2' reference, inside each module.

I get both or either engine to fail..

What you've got here, is a really nice, efficient, elegant add-on. I know that I can read/alter/write to simple text file, for the cumulative damage with C++... It'll just take me time to get comfy with this editor/compiler..

sc7500
May 1st, 2010, 15:18
...Per cubic inch, the above mentioned R2800 CB 16 is a deal! About $3,700/cyl or $25/cu inch. My Super cub engine was $6,240/cylinder or $78 per cu inch...

And people still think I'm crazy to build race engines for Sportsman dragsters...

For just under $10K I can make close to 1,000HP and move a 1400# car 0 to 100 in under 1.2 seconds...

But then, it's NOT flying like I'd prefer - just REAL close to the ground ! :icon_lol:
SC
:kilroy:

fliger747
May 3rd, 2010, 08:01
I any single engine airplane that haulls me and mine about, reliability is vital at the expense of volumetric efficency. Specific fuel consumption is also pretty important, especially at $ 4.75 or so a gallon for Av Gas.

Most of the GA engines are pretty old (simple) technology dating from the 40's. Modern materials and mfg methods have increased the quality. Some new non turbine technologies have been creeping in, such as the Thielert turbo diesel.

Of course when I go to work I have something like 250,000 hp in my right hand.....

Cheers: T

Brett_Henderson
May 4th, 2010, 02:45
UPDATE:

I've been running this (two-engine modification), pretty hard.. after a few more tweaks to the model's air-file (mostly around CHT).. I've got it working near perfectly on a non-turbocharged mod of Carenado's Seneca (basically a Seneca I ) ...

The key is to get the model's CHT to respond more realistically..and get it to where cowl-flaps and airspeed have realistic impacts on CHT..

teson1
May 4th, 2010, 13:33
Interesting.
Would you mind to share how you have done that?
Is it trial and error, or is there a systematic approach?
A hammering the CHT in place for dummies guide?? :wiggle:

Brett_Henderson
May 4th, 2010, 15:16
Interesting.
Would you mind to share how you have done that?
Is it trial and error, or is there a systematic approach?
A hammering the CHT in place for dummies guide?? :wiggle:

Just open the air file, with AirEd... You'll see an entry for CHT.. There are four parameters.. They effect the overall scale, the maximum, the cooling, and the response rate..

I'll post the numbers I've used, when I'm on my simming computer.. :jump:

fliger747
May 4th, 2010, 17:42
There are some serious problems with the way that FS derives CHT. It appears that it mostly relies on RPM, almost not at all on MP, somewhat on airspeed and cowl flap position. This probably dates back to the beginnings of FS with simple fixed pitch engine/prop combo's

An example of where such problems can crop up is on approach when the RPM's will be advanced for a possible go around, power is up slightly due to flap/gear drag and MP is low. In a real plane the CHT's will be fairly low, in FS they will go up. This can trigger engine malfunction parameters if they are linked to some real world CHT limit, if the scale and other values produce good values during the other stages of flight.

A gauge wizard is required to wave his wand to compensate for the basic system....

T

Brett_Henderson
May 5th, 2010, 02:57
I've gotten some pretty good results.. all phases of flight, with these numbers in a Carenado Seneca (will work well for any 200-300 HP piston prop, if tweaked):

teson1
May 5th, 2010, 06:24
Brett, thanks for the details. I'll have a try with them.

I'd quickly abandoned any focus on CHT as tests of normal CHT response on different acft gave unconsistent and unrealistic results.

But who knows, it may be worth a second look (though I have the feeling that I'll probably still run into the problems Tom has pointed out).

Thanks!

Gunter

teson1
May 5th, 2010, 07:44
That brings me to a larger question relating to real-world CHT importance.
(in particular in small GA piston engine planes)

- Under which conditions can/does CHT actually exceed temperature limitations in real-worls use???

Does CHT ever exceed limitations if the engine is healthy and maximum recommended operating conditions are respected? (i.e., are the engine designed so that limitations are normally not exceeded?)

During a normal flight, does the pilot have to continuously monitor CHT and regularly take action to keep CHT within limits?
Or is only exceptionally active action required?
Or are limitations only approached/exceeded if something is really wrong with the engine?

What are the conditions where overheating of the engine is commonly a concern for real pilots?

During what phases of the flight is overheating most likely?

Are there particular aircraft known to be more prone to overheating than other? Underdimensioned cooling systems?
Is one type of airplane more prone to overheating than another, e.g. GA vs high powered warbirds?

I feel this could be a huge topic due to all the different variables that may play a role, but I'm eager to hear any input.

Thanks!

Gunter

(And just a note re the release of RealEngine in case anybody is interested - still tweaking, so will take a little more than "a day or two" I've mentioned below.)

stansdds
May 5th, 2010, 08:36
There are some real pilots who frequent the boards, you might want to post a call for their help in the FSX and FS2004 forums and point them to this thread. I know Ken Stallings is a very experienced pilot.

fliger747
May 5th, 2010, 10:07
CHT has a number of uses, that and EGT. (1) you want the cylinders to warm enough before takeoff as a quick heating will cause the pistons to expand faster than the cylinders with predictible "issues". (2) you don't want the engine to cool too quickly with power reduction as cylinder cracking can occur. (3) CHT is used to adjust the cowl flaps and can be used to some extent to adjust mixture at altitude.

With the DC2 project we went around and around with CHT issues as we were attempting to replicate the actual climb and cruise values, requiring operation of the engines by the book. Where this fell down was in the low speed high RPM of approach where the engines would want to overheat since FS ignores manifold pressure. CHT was used to trigger engine malfunctions. The only cure is to use gauge technology to tie MP or developed HP to a non visible cowl flap (the DC2 had no cowl flaps) or bias the CHT reading in a similar manner.

All of this only becomes an issue in an engine that can approach the cooling limits.

Cheers: T

teson1
May 5th, 2010, 10:14
Stan, been there, done that (just now) ;) - thanks for the rec!
And I think we have at least Brett and fliger as active pilots in here.

teson1
May 5th, 2010, 10:26
... and I see fliger was mighty fast with a response- Thanks!

All of this only becomes an issue in an engine that can approach the cooling limits
Does that mean that many small GA planes might not even be able to exceed the temperature limitations, and that actually no particular action is needed to keep the CHT within limits?

Could you get the CHT on your Cub easily over the limit during a normal flight? (Does the Cub even have a CHT gauge??)
And how about if you pushed it?

(Your points (1) and (2) give interesting opportunity for including in a damage module once CHT behaves realistically :jump:)

Brett_Henderson
May 5th, 2010, 11:26
I flew a Cardinal-RG, where you'd have to TRY to make it overheat. I started thinking that it had cowl-flaps on it simply for training (it's a great complex trainer). The only time CHT got near red, was on steep, slow, long climbs.

Then there was this 182, where you didn't even want to start it, until you knew you could be up and flying soon.

I've flown a 310 that didn't have cowl-flaps at all.

There was a Mooney M20J, that had CHT gauges that acted like you'd think they would.

The keys there are, gauges and think. Older gauges aren't always accurate..

ANYway.. the only universal parameter here, is to just use them (cowl flaps) logically.. Apply tham as called for, and mostly to manage temp changes so that they aren't dramatic.

pilottj
May 5th, 2010, 11:51
high power settings and high angle of attack/climb will give you a warm CHT. Taking off in an area with rugged terrain around forcing you to maintain high climb rates and power settings will make you keep a close eye on the engine temp, especially in the warmer summer months. The A2A P-47 simulates this well. Take off on a warm day and climb at Vx and watch your temps stay warm even with cowl flaps open. When I flew for real, I would always prefer to cruise climb whenever possible. The same conditions can occur in your car, if you are driving up a hill in 2nd or 3rd gear, higher RPMs with a slower speed, less airflow through the engine...warmer engine.

Cheers
TJ

azflyboy
May 5th, 2010, 13:15
... and I see fliger was mighty fast with a response- Thanks!

Does that mean that many small GA planes might not even be able to exceed the temperature limitations, and that actually no particular action is needed to keep the CHT within limits?


Many GA aircraft are pretty resistant to overheating unless the pilot really abuses the engine. Aircraft are likely to operate in a wide range of temperatures, so most piston aircraft are designed to keep the engine cool under "worst case" circumstances, and therefore have excess cooling capacity at lower temperatures.

That said, some aircraft have cowling designs that cause engine temperatures to skyrocket without careful pilot monitoring, but those tend to be high performance aircraft with relatively tempermental turbocharged engines.

I work as a flight instructor in North Dakota and got my private certificate in Arizona, so I've had the chance to fly in temperatures ranging from +100F to -40F, and to see how aircraft engines react to those climates.

In Arizona summers, engine temperatures (all I had was an oil temperature) tended to run a bit warm, but they never got outside of the green arc in flight, even during prolonged full power climbs. Engine temperatures would tend to creep up during prolonged ground operations, but again, I never encountered a situation where the oil temp moved out of the normal range.

In North Dakota, we run into problems with the aircraft (Piper Warriors and Cessna 172's) actually having too much cooling in the winter. When the temperature starts getting close to freezing, the aircraft are fitted with plastic baffles that either restrict airflow into the cowling (for the Cessnas) or block airflow past the oil cooler (for the Warriors).

Without those baffles in place, the engines (which are air cooled) can be literally incapable of warming up to normal operating temperatures, since there's just too much cooling of the engine taking place.

During really cold weather (-30 and below), the engines are clearly unhappy about having to work in those temperatures. Even with the winterization plates installed, it can take 10 minutes for the engine oil to warm up to the point where takeoff is allowed, and anything but smooth movements of the throttle when adding power results in either backfiring and hesitating or (occasionally) the engine simply quitting.

tigisfat
May 5th, 2010, 15:01
You asked about CHT theory:

cylinder head temp is just a way to measure the temperature at which the engine is running. Many aviation aircraft are air-cooled, so you can't measure the coolant temp. For the most part, it's affected the same way as any other engine temperature metric; that is to say, anything that would make the engine run warmer will increase CHT.

Making the mixture more lean will increase CHT.
less airflow will increase the CHT, just like a lack of coolant in a car.
Making the engine run harder and for longer periods of time will increase CHT
Increased ambient temps will increase CHT.
A lack of engine lubrication will raise EGT, after engine lube temps rise.

Snave
May 5th, 2010, 15:07
Cylinder Head Temperature is not just a gauge reading by itself, it's also used as an indicator to the overall `health` of an engine. The CHT is a simple screw-in device that measures - unsurprisingly - the latent temperature in what is the hottest part of any engine. Too hot and detonation can occur - the fuel/air mix ignites before the engine wants it to. Also, too hot and the metal in the engine starts to lose structural integrity. This would be an extreme example.
Too cold and the engine can suffer from `shock cooling` where too-rapid cooling of the cylinder head shortens the life of the engine considerably, and in extreme cases can crack the head itself - differential expansion is a beeatch! So CHT is one to watch!

Others have expanded on the readings and how aspects of flight can affect but I can tell one other aspect that receives little coverage, but is actually also a small contributory factor.
First, let's emphasise that most AIR-cooled aircraft engines are the ones that need to have a weather eye kept on the CHT - liquid-cooled engines do not usually suffer from overheating in the air (but can on the ground). As with cars, radiators and oil coolers can manage to keep the engine and cylinders within limits under most conditions, most of the time. The early Spitfire, for example, had only a single underwing radiator and this was partly masked by the undercarriage leg. Even idling the Spit cuold - and did - overheat.

However, the cylinder cooling on any aircraft is a compromise - it must deal with the full gamut of temperatures encountered in the real world, it must deal with the highest demand on cooling - high power and low airspeed - and yet must be closely-cowled enough not to cause excessive drag, disrupt airflow, allow for the best possible visibility, and other factors. It follows that airflow optimisation can be done using flow pattern analysis and wind tunnel experiments to discern the optimum shape, size and location for `normal` use, but never for every conceivable one...

But I once experienced strangely high CHT readings in flight in a Piper Archer which defied attempts to understand until a fast jet jockey who was also a member of the club explained it - I had been flying at normal cruise (in fact at lower than normal cruise as there was a really strong tailwind that day and my groundspeed was over 140 knots - at 55% power! In an Archer!) but noticed that CHT was climbing slowly and inexorably. It wasn't a major cause for concern as I was closing on the destination field anyway, but even after I reduced power for descent, the CHT continued to climb! This obviously had me worried, and my thoughts started running through the possibilities - engine trouble, blocked air intake, detonation, even a faulty sensor, but the engine ran sweetly with no other indication of a problem and, thankfully as I turned base and reduced power still further, the temps turned downwards and declined slowly and steadily right back to normal levels. I landed normally, parked up, noted the log and had a word with the engineer. He decided to run it up on the ground and check how long it took to reach normal temperature, and found it totally normal.

We discussed the possibilities in the clubhouse for quite some time and even got some rather esoteric suggestions such as bird strike, ice blockage and dodgy fuel to add to the list until the fast jet guy piped up:
"Was there a lot of wind that day..?"
When I pointed out the groundspeed indication he nodded and said simply:
"What you probably had was diminished pass-through effect of the cooling air caused by a pressure build up to the rear of the engine - where the heat normally escapes... that `reversed` pressure, even if it's only a few knots relative, can upset the pattern of flow and disrupt the exhaust of the hot air."

It then became obvious why the temps had stopped rising and returned to normal - I'd descended from the high speed, then turned base, presenting a completely different resolved angle of airflow to the vents and inlets, and `normal` airflow had resumed, carrying away the trapped hot air from the cowling. I believe that this is much more of a problem for `pusher` aircraft.

Apparently the same effect has been seen in fast military jets up in the jetstream where the strong tailwind can delay by a fraction the jet efflux, causing localised `hot spots` in the tailpipe.

Hope this adds to the information bank!

Ken Stallings
May 5th, 2010, 15:57
You asked about CHT theory:

cylinder head temp is just a way to measure the temperature at which the engine is running. Many aviation aircraft are air-cooled, so you can't measure the coolant temp. For the most part, it's affected the same way as any other engine temperature metric; that is to say, anything that would make the engine run warmer will increase CHT.

Making the mixture more lean will increase CHT.
less airflow will increase the CHT, just like a lack of coolant in a car.
Making the engine run harder and for longer periods of time will increase CHT
Increased ambient temps will increase CHT.
A lack of engine lubrication will raise EGT, after engine lube temps rise.

Overall a very accurate and comprehensive summary. However, lack of oil lubrication can also increase CHT even more than EGT. Exhaust gas temperature can increase if the engine block is hotter, but more likely lack of lubrication will cause increased friction in the engine block, especially the pistons, and therefore increase CHT.

The two most common causes of CHT increase is too lean a fuel mixture for the conditions, especially during climb on a hot day. This is followed closely by high angle of attack climbs even when the mixture is fully enriched. This is why pilots are advised to enrich the mixture to full during a full power climb and to only lean it as the reduction in CHT allows.

There are a couple of methods to increase quality of cool airflow through the engine. A prime one is opening up cowl flaps as this increases the avenue of air to escape out the back of the engine, creating more of a vacuum up front to assist in drawing in more cooling air at the intake. Another is to simply decrease the climb rate, increase climb airspeed, and therefore the influx of cooling air in the intake.

Fuel acts as a liquid coolant in a piston engine. I know this might sound strange, but it is very true. This is why enriching the fuel mixture can reduce CHT very quickly.

One of the best reasons to have a digital engine monitor is to keep up with CHT for each cylinder. Then, soon as you notice the CHT is climbing too high, you can immediately take steps to remedy the problem.

The most immediate problem with high CHT is predetonation of fuel in the cylinders. The CHT reaches a high enough temperature so that the fuel sprayed into the cylinder detonates before the full compression stroke is completed. This causes the piston to be slammed down before the crankshaft makes its natural rotation and is aligned properly for a smooth power stroke.

This can cause multiple catastrophic problems rapidly. It can shear the crankshaft, destroy the piston attachments on the crankshaft, crack a cylinder head, or a piston or piston shaft, and even cause fuel to spray out and ignite in the engine bay causing a fire.

You can feel and hear the predetonation and I've been told it is a very uncomfortable sound to hear! If it isn't stopped immediately, it can lead to vastly more uncomfortable sounds and ultimate an extremely uncomfortable silence!

Ken

Brett_Henderson
May 5th, 2010, 17:48
I'm gonna have to respectfully refute the tailwind theory.. The airplane (or its engine) has no idea what the winds aloft are. Now, that a pilot might choose to fly at a slower TAS because of a tailwind, that lesser TAS could lower the cooling effect.. but there is no reverse pressure to the cooling system from a tailwind. The only time that could happen, is right after a wind-shift, and it would quickly equalize. For a jet, at jet-stream speed, that might be a problem when they transition a shear.., but for light GA, it's a non-issue. A tailwind simply increases ground-speed.

Remember.. wind is a ground-based phenom.. to the airplane in flight, there is no wind.

Ken Stallings
May 5th, 2010, 18:27
I'm gonna have to respectfully refute the tailwind theory.. The airplane (or its engine) has no idea what the winds aloft are. Now, that a pilot might choose to fly at a slower TAS because of a tailwind, that lesser TAS could lower the cooling effect.. but there is no reverse pressure to the cooling system from a tailwind. The only time that could happen, is right after a wind-shift, and it would quickly equalize. For a jet, at jet-stream speed, that might be a problem when they transition a shear.., but for light GA, it's a non-issue. A tailwind simply increases ground-speed.

Remember.. wind is a ground-based phenom.. to the airplane in flight, there is no wind.

I agree. Airspeed, especially indicated airspeed, is entirely relative to the force of air coming across the airframe. That is why indicated airspeed is, by definition, difference between static air pressure vice pitot tube ram air pressure. Therefore, by definition, if you are flying at 100 KIAS then it doesn't matter what your tailwind is, you have the same differential in air pressures as you would at 100 KIAS with the same headwind component.

I think you are precisely correct with regard to wind shears.

This is precisely why microbursts can be so very dangerous because the rapid shift of relative wind in speed and/or direction can happen so fast, that the momentum of the aircraft cannot adjust to keep the indicated airspeed consistent. Ultimately this could in extreme conditions lead to immediate stall or overspeeds, a situation especially dangerous during an instrument approach due to being at slow approach speed and being so close to the ground.

However, if the changes in wind happen in their more normal gradual rate, the aircraft's inherent momentum will adjust and the airspeed quickly restore itself to its previous value. If a tailwind shifts to a headwind, then the reduction in groundspeed translates into a loss of forward momentum of the aircraft and that allows the indicated airspeed to remain the same because that loss of momentum matches the increased forward force of air mass. In the reverse, where a headwind turns into a tailwind, the aircraft gains forward momentum to match the increase in tailwind force, and therefore again, the airspeed remains constant. In both cases, under normal conditions, the changes in airspeed are slight and very brief. And during that transition, you experience turbulence on the airframe.

Cheers,

Ken

fliger747
May 5th, 2010, 19:10
The cub never ever comes even close to getting too hot, but it is an airplane with a pretty open cowl, only four cylinders and a low airspeed range. My partners Cessna 180, which I flew back from Anchorage the other day has pretty sophisticated egt/cht etc instrumentation. Cylinders will vary, in that plane it's #6 that you have to keep an eye on. Not a real problem compared to a large radial with say 18 cylinders and closely cowled to minimize cooling drag. None of the GA planes I have flown from 185's to Seneca's had much of a cooling issue with sensible use of the cowl flaps...open on the ground and takeoff initial climb and otherwise mostly shut...

CHT is probably the most poorly modeled parameter in FS. They should have coupled it to EGT.....

Cheers: T

teson1
May 6th, 2010, 01:43
fliger, Brett, pilottj, azflyboy, tigisfat, Snave, Ken,

Wow, thanks to all of you for the great feedback!

I have a much better understanding of the real-world impact of CHT now, and the conditions that may cause concerns.

So, in some planes, the pilot will really want to pay close attention to CHT!

Thanks again! :salute:

Gunter

Snave
May 6th, 2010, 01:59
I'm gonna have to respectfully refute the tailwind theory.. The airplane (or its engine) has no idea what the winds aloft are. Now, that a pilot might choose to fly at a slower TAS because of a tailwind, that lesser TAS could lower the cooling effect.. but there is no reverse pressure to the cooling system from a tailwind. The only time that could happen, is right after a wind-shift, and it would quickly equalize. For a jet, at jet-stream speed, that might be a problem when they transition a shear.., but for light GA, it's a non-issue. A tailwind simply increases ground-speed.

Remember.. wind is a ground-based phenom.. to the airplane in flight, there is no wind.

Respectfully, wind is a relative variable in the aviating world like any other. Although the aircraft is flying at a speed within the airflow, if it is not travelling directly in the path of a particularly strong wind then there is a relative velocity vector component to the air mass movement around the aircraft which is exactly the same as the crosswind impact and which can `blank` intakes, exhausts and ducts in the same way as a T-tailed aircraft can be blanked at high AOA by wings and fuselage - and given the relative stability of even GA, there will always be some lag between wind vector and velocity change and the aircraft or pilot responding. At extremes that variance can impact on localised surfaces not directly dynamic through control of airflow like wings and empennage.

The key indicator for me, on that day, was that the CHT continued to increase AFTER a power reduction. There was an outside factor influencing the cooling of the cylinder head, and it was eliminated by changing the relative wind, and descending. I think on balance, it is still the likeliest explanation, although I readily accept that I might also have strayed into a pocket of volcanically heated air and ash that partially blocked the inlets. But I don't think there were any eruptions around that time!:wiggle:

Brett_Henderson
May 6th, 2010, 03:20
You've definately got a head-scratcher here, as to why the high CHT... I'd suggest that you go fly around at that same IAS, and see if that's the problem. Whatever IAS it was, it sounds like there might be a resonant sweet (sour) spot for cooling airflow, at that IAS.


Although the aircraft is flying at a speed within the airflow, if it is not travelling directly in the path of a particularly strong wind then there is a relative velocity vector component to the air mass movement around the aircraft which is exactly the same as the crosswind impact and which can `blank` intakes, exhausts and ducts in the same way as a T-tailed aircraft can be blanked at high AOA by wings and fuselage - and given the relative stability of even GA, there will always be some lag between wind vector and velocity change and the aircraft or pilot responding. At extremes that variance can impact on localised surfaces not directly dynamic through control of airflow like wings and empennage.


There is no relative vector.. there is no in-flight, X-wind blanking (except during a slip.. and that has nothing to do with the wind.. it's a function of "fighting" the wind relative to the ground.. like trying to stay lined up with a runway..and could be replicated, in no wind at all).

An airplane doesn't know that it's "crabbing" to stay on course.. Wings and control surfaces and air-intakes/outlets have no reference to the ground.. They're all the proverbial fish in a giant aquarium. That the aquarium might be moving is of no concern to his fins or gills as he swims around inside of it..

Brett_Henderson
May 6th, 2010, 03:26
Now..let's say that it's a glass-bottomed aquarium.. When the fish tries to not only swim toward a "runway" underneath the aquarium, but also keep his body lined up with the runway as the aqurium keeps moving.. that "slipping" will have one of his gills seeing a different water-flow than the other gill.. but not if he's just crabbing toward the runway.. Make sense ?

rvn817j
May 6th, 2010, 05:40
CHTs - In my RV-8 I experience most CHT issues on 'hot'/humid days (e.g., 80 degrees f and above) at high power settings and/or higher angles of attack (air flow over the cylinders is reduced). So, for example, shortly following takeoff, I have to be looking at CHTs and many times I will reduce power slightly to keep CHTs in the normal range. Sometimes, at lower altitudes (2000 - 3500 feet) at higher power settings in straight and level flight, I also experience CHTs inexcess of normal. Again, a slight power reduction will solve the problem.

As you climb, standard temperature deviation is -2 degrees f per 1000 feet altitude (or you have an outside air temperature probe installed to determine it). Cool air helps greatly with CHTs. But, you don't want it too cool either because that could cause other issues.

Google Lycoming O-360, for example, to get engine operating parameters.

teson1
May 6th, 2010, 14:55
Jay, thanks for the input.
The hands-on description of real-world handling you and the others have contributed is exactly what I was looking for. Great!

Sunny9850
May 6th, 2010, 19:01
I think the others have already covered most of the basics better than most textbooks do it.

A few more examples to what can affect the CHTs in one particular airplane.

CG...because it will alter the overall pitch of the aircraft at a given airspeed and power setting. This in turn changes how the air enters the cowling and how effective it will move through the cowl....and therefor cooling the cylinders.

Air Density...less dense air simple means there are less molecules in a given space to interact with the hot engine. And most likely you are going to ask the engine to work harder to achieve the desired performance.

The Baffling in the cowling is extremely crucial. Even a relatively small "crack" between the flexible baffling and the cowling can change how hot the engine gets.
The design of the Prop, cowling openings and such of course are very important as well.
If I had the $9000.00 I would love to swap the standard Harzell prop on my Saratoga for one of their Scimitar models. Not only does that new prop run smoother and quieter, provide more thrust in almost all flight regimes it also shuffles much more air into the cowl openings. And while "Sara" usually doesn't have CHT issues despite living in SoCal...a few degrees less would not hurt anything.

Speaking of cowlings...my 1982 Saratoga has the relatively large dual nostrils in the upper half of the nose.
Piper has updated that a while back with to round, smaller openings (LoPresti has a very similar looking design available) which actually improve both cooling and reduce drag.
And of course there was the hideous looking Turbo Lance with a single large opening below the prop....very very efficient in both cooling and drag.............but not even a mother could possibly love that face :D :D

As for the tailwind causing a hotter engine....don't think so. Unless the airplane was literally sitting on top of an even faster moving flow which might then indeed cause a bit of a "blockage" of the outflow opening on the bottom of the cowl.

The highest GS I ever got with the Archer I flew before Sara was 172 kts. SoCal ATC actually came back and one time after checking in with a new sector and asked me to confirm that I was indeed flying a PA28-180.
The highest recorded GS in the Saratoga so far is 202 kts....recorded in her GNS 530 :D :D flying back from Castle last year.

Stefan

fliger747
May 6th, 2010, 19:12
Best sustaimed ground speed to date.... 709 knots. CHT not much of an issue with the turbines at 35,000'.

Cheers: T

Snave
May 7th, 2010, 14:31
Now..let's say that it's a glass-bottomed aquarium.. When the fish tries to not only swim toward a "runway" underneath the aquarium, but also keep his body lined up with the runway as the aqurium keeps moving.. that "slipping" will have one of his gills seeing a different water-flow than the other gill.. but not if he's just crabbing toward the runway.. Make sense ?

Ah but if it's a 4-knot fish and the water in the aquarium water is quartering at 8 knots then there is a component of cross-flow. assuming the fish can't go 4 knots at a vector from straight ahead. He may be able to maintain relative alignment with the runway - and his perceived velocity vector stays the same over the runway centrelines - but he's actually swimming in a cross flow - same effect as ground speed v. indicated air speed. He's converted his 4 knots into a lateral and forward motion the cumulative effect of which is to retain position in one plane (sic).

I could quote some strange anomalies of similar ilk from my submarine days, involving some undersea currents in certain parts of the world, but I'm not sure I'm allowed to...:salute:

I must admit I furrowed my brow at the explanation, and think it was simplistic for the hard of understanding like me, but all craft of any weight (and fish) have an inertia when inserted into a fluid medium (and one doesn't normally argue with a Tornado pilot with Amraams...)

What I think I might have experienced was akin to response lag or possibly some kind of pressure differential inside the cowling. I know and comprehend what you are saying about the aircrafts perception of its own trajectory in the medium, but as we all know, you don't apply 180hp from a standing start and immediately go flying. Speed builds gradually and velocity changes are not instantaneous. Our concoctions of metals and plastics, woods and fabric take time to respond to change. And with a higher mean speed as a tailwind, the proportional change in percentage terms is a greater velocity in absolute terms.

Possibly, it is this rate of change that may have been the cause.

To this day I still cannot come up with a better alternative explanation - and at the time I did consult one of my aviating mentors - my other `alfs sisters hubby with over 12,000 commercial and military hours including rotary wing on rig and SAR duties and he couldn't think of anything else that explained it. The other thing that persuades me is that my subsequent career has involved spending long hours in wind tunnels - where wind speed can be changed violently and very quickly - and have noted similar changes in internal combustion engines where the platform has been rotated relative to the airflow at the same time as the velocity has been altered even when the engines are liquid-cooled so should dampen the effect substantially.

Brett_Henderson
May 7th, 2010, 14:56
Unless the 4knot fish is consciously swimming partially sideways (ala slipping to not only approach the runway on runway centerline(crabbing), but also be "pointing" runway centerline(slipping)), it wouldn't matter if the aquarium were moving 100knots.. there is no crossflow to him, his fins, or gills.


ANYway.. you seem to have a good understanding of fluid dynamics.. and do seem to see the merit to the reason why it's sound argument to say that there's no way a tailwind means anything to the cooling flow. But you've got a mental block that won't let go of the idea that it could..

Your points about inertia/momentum are very accurate.. in that a wind CHANGE could have a temporary effect on the cooling flow, but unless it's constantly changing (to the point that you'd be beaten alive by the turblence effect), it doesn't take but a few seconds for it to equalize... not nearly long enough to affect cooling in any meaningful way. And if it's a sustained tailwind (like we're talking about), there's absolutely no effect on cooling, at all. This isn't me liking to argue.. this is aerodynamic fact.

I'll admit to having trouble forcing my self to "see" it too. Like.. my instinct is that if an airplane is flying a perfect circle in a steady wind, that the airplane would "feel" the wind differently, during different parts of the circle... but it does not.

fliger747
May 7th, 2010, 19:15
Given the relation of aircraft speed and the magnitude of any reasonable wind change, and the rate at which an airplane can change direction, any effects are very transitory and not liable to effect engine cooling which has it's own significant thermal inertia.

Light aircraft adjust more quickly to a changing local dynamic environment, and large ones more slowly. In a very large aircraft such as the 747 this can actually work to our advantage. This is especially true in cross wind landings......

Cheers: T

Sunny9850
May 8th, 2010, 17:57
Best sustaimed ground speed to date.... 709 knots. CHT not much of an issue with the turbines at 35,000'.

Cheers: T

LOL Woopdidu.....seat 7B Heathrow to NY JFK the digital display in a certain British-French aerial machine showed much more than that but I wasn't flying it :D
But I have seen much more than those speeds I mentioned in the left seat of C-441, Be-58G and AC550... but none of those were Piper Archers like the one in the story ;) and I did not mention it to brag that my Archer was faster....simply to note that I understand the notion of immense pride when a usually rather slow steed suddenly develops "wings" :D :D

Stefan

teson1
June 14th, 2010, 12:49
Hi,
I finally uploaded RealEngine v1.1 to SOH and flightsim.

Please do not use v1.0 uploaded yesterday! I made a stupid mistake - uploaded an old zip version with same name from another folder... possibly partly non-functional.
I did test and retest everything was working fine prior to releasing, I swear. Tested the zip. And then this stupid error... :banghead:

My sincere appologies to those who have downloaded v1.0. :redf:

Gunter

And now I need some flying.

Brett_Henderson
June 21st, 2010, 10:00
Someone uploaded it to Simviation, too (I'm assuming you).. and a thread has commenced... I posted suggesting a devoted, RealEngine Q&A thread.. I'll monitor it and answer questions, best I can..

fliger747
June 22nd, 2010, 09:29
The biggest problem with the way CHT is computed by FS is that it is primarially related on the heat generating side to RPM. I believe this is a throwback to many assumptions in early FS days, using a small fixed pitch prop driven aircraft where this might be somewhat true. Airspeed is taken into account in the "cooling factor" scalar in the .air file, but with a constant speed prop one can be in the strange situation in FS of generating a CHT overheat at slow speeds on approach with low MP but high RPM.

Most FS operators ignore CHT, ot the values generated in most phases of flight are too low so it is never an issue. It would have been perhaps better if the heat generating side of CHT were linked to EGT...

Cheers: T

teson1
June 22nd, 2010, 09:32
Someone uploaded it to Simviation, too (I'm assuming you)..
Well.. actually I didn't. And the readme and manual are pretty clear that upload is only allowed to flightsim, SOH and avsim... :173go1:

I'm not surprised it can be found on some ill-reputed sites like fsplanet.
I'm more surprised to find it at simviation, which seems to be a sensible site. I hope that has just slipped through the review process.

Thanks for the HU regarding the discussion!