Cooling the BS Bonanza

[orchestra_nl 958]

I have an engine health issue with the BlackSquare Analog Bonanza.  It seems that with every landing my engine health drops 2%.
1% is removed during rollout/taxi and the other when I shut down the engine.

My guess is that I let the engine cool down too fast but I am unsure how to prevent that.
During descent I set the mixture to full rich and try to gently pull down the throttle (to about 8 gal/h fuel flow.
I can use more throttle after landing but then I have to ride the brakes.

Anyone know how it is done?

[ryanbatc 13,038]

With the turbocharger normally it's not more than 2" per 2 minutes decrease.

Not sure if it being a turbo normalized affects that.

Also you could try cowl flaps closed to keep things warmer.

Edited April 24, 2023 by ryanbatc

[orchestra_nl 958]

11 minutes ago, ryanbatc said:

With the turbocharger normally it's not more than 2" per 2 minutes decrease.

Not sure if it being a turbo normalized affects that.

Also you could try cowl flaps closed to keep things warmer.

Thanks. I already closed the cowl flaps but I probably decrease the throttle too fast. Will try to close the throttle slower and see whether that helps.

[ryanbatc 13,038]

1 hour ago, orchestra_nl said:

Thanks. I already closed the cowl flaps but I probably decrease the throttle too fast. Will try to close the throttle slower and see whether that helps.

Hehe yeah.  Unfortunately I don't enable the failures usually because is just want a nice flight haha (rarely even have time to fly these days).  But I'd bet money that I'd shock cool all my engines in flightsim.

[Fielder 3,744]

My juvenile humor: I think it a shame that Black Square does not make a steam gauge Apache Helicopter.

 

 

[fppilot 4,398]

6 hours ago, orchestra_nl said:

Thanks. I already closed the cowl flaps but I probably decrease the throttle too fast

I have no experience with real life aviation turbo's but if an automotive sense were applied to aviation I would doubt the turbos would even be in play during descent and approach.  Primarily on TO, climb, and hi-speed cruise. Does cold shocking in aviation engines not occur with throttling back too quickly from high speed cruise? 

Those with actual aviation turbo experience?  Am I out to lunch on that?

Edited April 24, 2023 by fppilot

[ndts 59]

Shock cooling airplane engines is something of an "old wives tale", since you'll see people talking about it, but operations that should be going through cylinders like crazy if shock cooling was common (flight schools and skydiving operations) largely don't have any issues related to it. 

On engines with reduction gears, rapidly reducing the power (or reducing it too far) can result in a situation where the propeller is driving the gearbox, which isn't good for the engines, but damage from thermal shock after a power reduction isn't common.

https://www.avweb.com/ownership/shock-cooling-time-to-kill-the-myth/

[orchestra_nl 958]

3 hours ago, ndts said:

Shock cooling airplane engines is something of an "old wives tale", since you'll see people talking about it, but operations that should be going through cylinders like crazy if shock cooling was common (flight schools and skydiving operations) largely don't have any issues related to it. 

On engines with reduction gears, rapidly reducing the power (or reducing it too far) can result in a situation where the propeller is driving the gearbox, which isn't good for the engines, but damage from thermal shock after a power reduction isn't common.

https://www.avweb.com/ownership/shock-cooling-time-to-kill-the-myth/

I could be mistaken but IIRC from the Justflight video they had implemented shock cooling as a failure option .. Might be wrong though, will have to watch their anouncement video again.
If it is not shock cooling I wonder what could take away 2% on every landing. Now, if it was on takeoff I could name one or two causes for increased wear and tear but landing?
Perhaps I will ask on the JF forums about this.

Edit, just found this on their forums:

Quote

here is a list of all the conditions that can reduce the health of the engine:

(A:ENG MANIFOLD PRESSURE:1, inhg) > 32
(A:PROP RPM:1, rpm) > 2750
(A:RECIP ENG CYLINDER HEAD TEMPERATURE:1, CELSIUS) > 230
(A:ENG EXHAUST GAS TEMPERATURE:1, CELSIUS) > 870
(A:ENG OIL TEMPERATURE:1, CELSIUS) > 110
(L:var_ShockCooling_1, FAHRENHEIT) > 70

The first 2 are definitely NOT the case but I will have to watch the others. ShockCooling seems indeed to be a factor.

Edited April 25, 2023 by orchestra_nl
JF forums

[hs118 730]

 

31 minutes ago, orchestra_nl said:

ShockCooling seems indeed to be a factor.

After taking a look at the coding, it would be easy to disable this feature.

Edited April 25, 2023 by hs118

[Glenn Fitzpatrick 3,799]

The Shock Cooling argument is reminiscent of discussions about static protection when handling RAM.  Most self taught home PC builders are convinced it  is a thing of the past but the problem is the sort of damage static allegedly does only shows up intermittently, underload or after a longish time rather than immediately so the tendency is to blame the RAM when faults do occur, not installation incompetence.

With regard to Shock Cooling:

- if shock cooling is a thing at all, it only happens at very high CHT otherwise simply shutting down the engine on the ground after a flight would cause it

- piston engines like Continental and Lycoming never seem to get hot enough for shock cooling though Lycoming themselves definitely say it can be a thing - https://www.lycoming.com/content/how-avoid-sudden-cooling-your-engine

- logically it is more likely to be an issue on big radials or potentially in a turbocharger but that is conjecture

That said, if your POH  on your $100,000 plus real-life  airplane says "avoid shock cooling" I would listen to that rather than some anecdotal story from the internet about it being a myth

Edited April 25, 2023 by Glenn Fitzpatrick

[hs118 730]

1 hour ago, Glenn Fitzpatrick said:

With regard to Shock Cooling:

- if shock cooling is a thing at all, it only happens at very high CHT otherwise simply shutting down the engine on the ground after a flight would cause it

The coding in the BS Bonanza could be changed to reflect higher temperatures required for damage based on what I am seeing.

[fppilot 4,398]

3 hours ago, orchestra_nl said:

(L:var_ShockCooling_1, FAHRENHEIT) > 70

So anyone know what it is that is >70?  I read the variable name, L:var_ShockCooling_1, and I see the value range, >70.   But from the left seat, flying the BS Bonanza, what is it that is under my control that I can observe and avoid during the period from engine start to engine shut down?  That is the key question about their implementation of shock cooling.  I would guess it references a temperature drop of >70°F, but of what observable temp indication  and over what period of time?

Edited April 25, 2023 by fppilot

[hs118 730]

59 minutes ago, fppilot said:

So anyone know what it is that is >70?  I read the variable name, L:var_ShockCooling_1, and I see the value range, >70.   But from the left seat, flying the BS Bonanza, what is it that is under my control that I can observe and avoid during the period from engine start to engine shut down?  That is the key question about their implementation of shock cooling.  I would guess it references a temperature drop of >70°F, but of what observable temp indication  and over what period of time?

My guess, after looking at the code, is that the value of L:ShockCooling_1 is being calculated in the model itself. I found no references that calculate the variable in the xml code. The only code reference is a line checking the value against the constant "70" and then adjusting the failure threshold if needed.

This whole check of the variable can be commented out, deleted or the constant (70) changed/increased. 

Someone with more experience and knowledge regarding examination of the model itself may be able to find more info.

Edited April 25, 2023 by hs118

[orchestra_nl 958]

2 minutes ago, hs118 said:

My guess, after looking at the code, is that the value of L:ShookCooling_1 is being calculated in the model itself. I found no references that calculate the variable in the xml code. The only code reference is a line checking the value against the constant "70" and then adjusting the failure threshold if needed.

This whole check of the variable can be commented out, deleted or the constant (70) changed/increased. 

Someone with more experience and knowledge regarding examination of the model itself may be able to find more info, 

I browsed the manual but could not find a reference to this. I would think anything that can lead to failures is worth a mention.
In the meantime I found This document about shock cooling/heating. The article is very interesting and specifically mentions the Beech Bonanza

There were a few surprises in it: one is that full power at takeoff is better than limited power because the extra fuel flow helps cool the engine.
Another was that descending with the cowl flaps still open is not a good idea. I might have done that on a few occasions.

[hs118 730]

Great article find.