Lit Firecracker

spiderweb

spiderweb

Final Approach
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Ben
Richard Collins has said that the turbocharged engine in his C210 has all the properties of a "lit firecracker" to those who do not know how to handle it. I can understand that, but I am wondering, how much do intercoolers mitigate shock cooling and how much do wastegates prevent overboosting? Am I right that the new Senecas have those as standard equipment? Does this mean that you are dummy proofed?

As a side note, my CFI had always taught me to make gradual power changes , especially in descent, because this practice would help when I move to turbocharging.
 
while newer turbos with automatic wastegates do work pretty well against overboost in normal ops, a ham-fisted pilot can still treat the engine pretty harshly with large and abrupt power movements. It's not the best technique in a normally aspirated engine either.

As far as intercoolers go - their purpose is to cool down the air coming from the turbocharger into the intake, so that the air is denser and you effectively get better boost characteristics. I don't think they have any effect on shock cooling (if you believe in it).
 
spiderweb said:
Richard Collins has said that the turbocharged engine in his C210 has all the properties of a "lit firecracker" to those who do not know how to handle it. I can understand that, but I am wondering, how much do intercoolers mitigate shock cooling and how much do wastegates prevent overboosting? Am I right that the new Senecas have those as standard equipment? Does this mean that you are dummy proofed?

As a side note, my CFI had always taught me to make gradual power changes , especially in descent, because this practice would help when I move to turbocharging.
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The POH says 3" manifold reductions per minute, max. "Can't you hear those turbos groaning?"

On approach, always make the smallest power change that you can hear.

Senecas only have four power settings. Idle. 100%. 65%, and Approach. That is all. The intercoolers just make the induction cooler. You can still overboost them in a New York Minute.
 
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I can't see an intercooler directly affecting the shock cooling theory for a few reasons.

Also the wastegate controls the exhaust flow through the turbo, so its also indirectly related to an overboost situation.

In my experience with turbos, you just have to watch the application of power down at sea level mostly...
 
bbchien said:
The POH says 3" manifold reductions per minute, max. "Can't you hear those turbos groaning?"

On approach, always make the smallest power change that you can hear.

Senecas only have four power settings. Idle. 100%. 65%, and Approach. That is all. The intercoolers just make the induction cooler. You can still overboost them in a New York Minute.
Click to expand...

Bruce, are you referring to the latest model senecas (V, I think)?
 
spiderweb said:
Richard Collins has said that the turbocharged engine in his C210 has all the properties of a "lit firecracker" to those who do not know how to handle it.
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Dunno, but I think writing stuff like that scares people away from turbos unnecessarily. Of course you have to know how to handle it and pay attention to what you are doing, but that goes for the rest of flying too, no? :dunno:
 
I flew a T210 for 200 hrs and it was not a big challenge to manage the temps. Smooth application of throttle on take off and just plan ahead for descent. The taxi time to the ramp or the hangar usually took care of the "cool down" time.
 
Several friends fly their turbos straight to TBO. Might take a bit more care, but there are several OWTs out there.
 
I've always thought that the only reason to buy a turbocharged airplane was if you needed the fly higher ability the turbo provides. Otherwise, why spend the extra money on acquisition and up keep.

Looking at ads in TaP...it appears that lots of turbo charged aircraft get top overhauls about mid way through to TBO (give or take).

Len
 
I think you just have to treat them nice and they'll be good to you.
 
Len Lanetti said:
I've always thought that the only reason to buy a turbocharged airplane was if you needed the fly higher ability the turbo provides. Otherwise, why spend the extra money on acquisition and up keep.
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True, but that's different than comparing it to a "lit firecracker".

I have lots of time in airplanes with a similar engine/turbo configuration to a T-210 (C-206 and C-320) with no intercoolers. Because I worked doing aerial survey we would often take them up into the low 20s and back down again. I don't recall having any problems with engines not making it to TBO or having symptoms of shock cooling. But I was always gentle with the throttle when advancing it, and didn't go straight from cruise power to idle when descending. The planes were also flown by a very limited number of people. They weren't for rent.
 
Everskyward said:
True, but that's different than comparing it to a "lit firecracker".

I have lots of time in airplanes with a similar engine/turbo configuration to a T-210 (C-206 and C-320) with no intercoolers. Because I worked doing aerial survey we would often take them up into the low 20s and back down again. I don't recall having any problems with engines not making it to TBO or having symptoms of shock cooling. But I was always gentle with the throttle when advancing it, and didn't go straight from cruise power to idle when descending. The planes were also flown by a very limited number of people. They weren't for rent.
Click to expand...

All of my turbo experience has been with the Cont TSIO-520s as well.
 
Everskyward said:
I have lots of time in airplanes with a similar engine/turbo configuration to a T-210 (C-206 and C-320) with no intercoolers. Because I worked doing aerial survey we would often take them up into the low 20s and back down again. I don't recall having any problems with engines not making it to TBO or having symptoms of shock cooling. But I was always gentle with the throttle when advancing it, and didn't go straight from cruise power to idle when descending. The planes were also flown by a very limited number of people. They weren't for rent.
Click to expand...

I would imagine that airplanes flown very often, very well, on a very structured mission by a limited set of pilots all singing from the same hymnal would help contribute to the longevity.

Len
 
Longevity = 65%, except for takeoff and the first portion of climb, as well as descent. Keep temps low.
 
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