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Carb heat: my new policy. Any comments



 
 
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  #1  
Old September 6th 08, 05:58 PM posted to rec.aviation.piloting
Tman
external usenet poster
 
Posts: 68
Default Carb heat: my new policy. Any comments

Flying a lot of 152s and 172s with carb heat lately. When inbound, I've
been taught to pull the carb heat "on" downwind, hey actually use it as
a power control to slow the plane just a bit mid-field, and then more
importantly, just leave the thing on till clear of the runway and
cleaning up. No matter what the temp, humidity. And to have it on at
all times when the RPM is less than the green band. Kind of a preventative.

A few times I have been coming in on short final and needed a burst of
power due to a sudden downdraft, or needed to pour on a little juice
cause my approach was coming up just a bit short. Moving the throttle
forward 1/4 to 1/2 inch, i.e. giving it a little juice but certainly not
a go around type of thing, often times I would get a stumble, hicuup,
drop in RPM'S for 2-3 seconds before the horses responded.

Lot of convective turb lately and that power really comes in handy at
times on mid to short final. Kind of a shocker when the engine doesn't
respond quite nicely.

This has happened on a few birds, especially on hot days. I think
what's happening is the engine is just too rich, hey I've got the
mixture all the way in, it's hot (air less dense), and it's (way) hotter
with the carb heat on ( air much less dense), all enriching the mixture,
and when I put on a little power the accelerator pump in the carb
over-enriches the engine for just a little bit; causing the stumble.

Other pilots and the A&P just tell me to pour on the power a little slower.

I think I'm going to follow a new SOP. Turn the carb heat off on
mid-final. Reasoning: no carb, esp a warm one is going to ice up in 30
seconds, sets me up better for a go-around, and will prevent this
stumble business (I did test it out at altitude, and it prevents or at
least seriously mitigates the stumble).

thoughts?
T
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  #2  
Old September 6th 08, 07:33 PM posted to rec.aviation.piloting
Lonnie[_3_]
external usenet poster
 
Posts: 164
Default Carb heat: my new policy. Any comments


"Tman" [email protected] wrote in message
. ..
Flying a lot of 152s and 172s with carb heat lately. When inbound, I've
been taught to pull the carb heat "on" downwind, hey actually use it as a
power control to slow the plane just a bit mid-field, and then more
importantly, just leave the thing on till clear of the runway and cleaning
up. No matter what the temp, humidity. And to have it on at all times
when the RPM is less than the green band. Kind of a preventative.

A few times I have been coming in on short final and needed a burst of
power due to a sudden downdraft, or needed to pour on a little juice cause
my approach was coming up just a bit short. Moving the throttle forward
1/4 to 1/2 inch, i.e. giving it a little juice but certainly not a go
around type of thing, often times I would get a stumble, hicuup, drop in
RPM'S for 2-3 seconds before the horses responded.

Lot of convective turb lately and that power really comes in handy at
times on mid to short final. Kind of a shocker when the engine doesn't
respond quite nicely.

This has happened on a few birds, especially on hot days. I think what's
happening is the engine is just too rich, hey I've got the mixture all the
way in, it's hot (air less dense), and it's (way) hotter with the carb
heat on ( air much less dense), all enriching the mixture, and when I put
on a little power the accelerator pump in the carb over-enriches the
engine for just a little bit; causing the stumble.

Other pilots and the A&P just tell me to pour on the power a little
slower.

I think I'm going to follow a new SOP. Turn the carb heat off on
mid-final. Reasoning: no carb, esp a warm one is going to ice up in 30
seconds, sets me up better for a go-around, and will prevent this stumble
business (I did test it out at altitude, and it prevents or at least
seriously mitigates the stumble).

thoughts?
T


Shouldn't be a problem, but sometimes it happens.

Apply power a little slower.
or
Carry just a tiny bit of power on final. Sounds like you might be
approaching at cut off.
or
Bump a little power every 15 to 20 seconds to keep the engine clear.


Personally I wouldn't cut the carb heat.





  #3  
Old September 6th 08, 07:40 PM posted to rec.aviation.piloting
a[_3_]
external usenet poster
 
Posts: 562
Default Carb heat: my new policy. Any comments

On Sep 6, 12:58*pm, Tman [email protected] wrote:
Flying a lot of 152s and 172s with carb heat lately. *When inbound, I've
been taught to pull the carb heat "on" downwind, hey actually use it as
a power control to slow the plane just a bit mid-field, and then more
importantly, just leave the thing on till clear of the runway and
cleaning up. *No matter what the temp, humidity. *And to have it on at
all times when the RPM is less than the green band. *Kind of a preventative.

A few times I have been coming in on short final and needed a burst of
power due to a sudden downdraft, or needed to pour on a little juice
cause my approach was coming up just a bit short. *Moving the throttle
forward 1/4 to 1/2 inch, i.e. giving it a little juice but certainly not
a go around type of thing, often times I would get a stumble, hicuup,
drop in RPM'S for 2-3 seconds before the horses responded.

Lot of convective turb lately and that power really comes in handy at
times on mid to short final. *Kind of a shocker when the engine doesn't
respond quite nicely.

This has happened on a few birds, especially on hot days. *I think
what's happening is the engine is just too rich, hey I've got the
mixture all the way in, it's hot (air less dense), and it's (way) hotter
with the carb heat on ( air much less dense), all enriching the mixture,
and when I put on a little power the accelerator pump in the carb
over-enriches the engine for just a little bit; causing the stumble.

Other pilots and the A&P just tell me to pour on the power a little slower.

  #4  
Old September 6th 08, 07:45 PM posted to rec.aviation.piloting
John Smith
external usenet poster
 
Posts: 256
Default Carb heat: my new policy. Any comments

Tman wrote:

Flying a lot of 152s and 172s with carb heat lately. When inbound, I've
been taught to pull the carb heat "on" downwind, hey actually use it as
a power control to slow the plane just a bit mid-field, and then more
importantly, just leave the thing on till clear of the runway and
cleaning up.


Never heard of this before.

I think I'm going to follow a new SOP. Turn the carb heat off on
mid-final.


Tha't what I've always been taught. Actually, I do it on short final.
There will come the day when you need full power for the go-around. Too
silly if you then have the carb heat on.
  #5  
Old September 6th 08, 08:03 PM posted to rec.aviation.piloting
Jon Woellhaf
external usenet poster
 
Posts: 221
Default Carb heat: my new policy. Any comments

I was taught to push in the carb heat with my thumb while advancing the
throttle for a go-around.

"John Smith" wrote in message
...
Tman wrote:

Flying a lot of 152s and 172s with carb heat lately. When inbound, I've
been taught to pull the carb heat "on" downwind, hey actually use it as a
power control to slow the plane just a bit mid-field, and then more
importantly, just leave the thing on till clear of the runway and
cleaning up.


Never heard of this before.

I think I'm going to follow a new SOP. Turn the carb heat off on
mid-final.


Tha't what I've always been taught. Actually, I do it on short final.
There will come the day when you need full power for the go-around. Too
silly if you then have the carb heat on.



  #6  
Old September 6th 08, 08:03 PM posted to rec.aviation.piloting
Mike[_22_]
external usenet poster
 
Posts: 466
Default Carb heat: my new policy. Any comments

"Lonnie" @_#~#@.^net wrote in message
...

"Tman" [email protected] wrote in message
. ..
Flying a lot of 152s and 172s with carb heat lately. When inbound, I've
been taught to pull the carb heat "on" downwind, hey actually use it as a
power control to slow the plane just a bit mid-field, and then more
importantly, just leave the thing on till clear of the runway and
cleaning up. No matter what the temp, humidity. And to have it on at
all times when the RPM is less than the green band. Kind of a
preventative.

A few times I have been coming in on short final and needed a burst of
power due to a sudden downdraft, or needed to pour on a little juice
cause my approach was coming up just a bit short. Moving the throttle
forward 1/4 to 1/2 inch, i.e. giving it a little juice but certainly not
a go around type of thing, often times I would get a stumble, hicuup,
drop in RPM'S for 2-3 seconds before the horses responded.

Lot of convective turb lately and that power really comes in handy at
times on mid to short final. Kind of a shocker when the engine doesn't
respond quite nicely.

This has happened on a few birds, especially on hot days. I think what's
happening is the engine is just too rich, hey I've got the mixture all
the way in, it's hot (air less dense), and it's (way) hotter with the
carb heat on ( air much less dense), all enriching the mixture, and when
I put on a little power the accelerator pump in the carb over-enriches
the engine for just a little bit; causing the stumble.

Other pilots and the A&P just tell me to pour on the power a little
slower.

I think I'm going to follow a new SOP. Turn the carb heat off on
mid-final. Reasoning: no carb, esp a warm one is going to ice up in 30
seconds, sets me up better for a go-around, and will prevent this stumble
business (I did test it out at altitude, and it prevents or at least
seriously mitigates the stumble).

thoughts?
T


Shouldn't be a problem, but sometimes it happens.

Apply power a little slower.
or
Carry just a tiny bit of power on final. Sounds like you might be
approaching at cut off.
or
Bump a little power every 15 to 20 seconds to keep the engine clear.


Neither of which would do anything to prevent potential problems.



Personally I wouldn't cut the carb heat.


Because flight sim doesn't care either way.

  #7  
Old September 6th 08, 08:19 PM posted to rec.aviation.piloting
Mike[_22_]
external usenet poster
 
Posts: 466
Default Carb heat: my new policy. Any comments

"Tman" [email protected] wrote in message
. ..
Flying a lot of 152s and 172s with carb heat lately. When inbound, I've
been taught to pull the carb heat "on" downwind, hey actually use it as a
power control to slow the plane just a bit mid-field, and then more
importantly, just leave the thing on till clear of the runway and cleaning
up. No matter what the temp, humidity. And to have it on at all times
when the RPM is less than the green band. Kind of a preventative.

A few times I have been coming in on short final and needed a burst of
power due to a sudden downdraft, or needed to pour on a little juice cause
my approach was coming up just a bit short. Moving the throttle forward
1/4 to 1/2 inch, i.e. giving it a little juice but certainly not a go
around type of thing, often times I would get a stumble, hicuup, drop in
RPM'S for 2-3 seconds before the horses responded.

Lot of convective turb lately and that power really comes in handy at
times on mid to short final. Kind of a shocker when the engine doesn't
respond quite nicely.

This has happened on a few birds, especially on hot days. I think what's
happening is the engine is just too rich, hey I've got the mixture all the
way in, it's hot (air less dense), and it's (way) hotter with the carb
heat on ( air much less dense), all enriching the mixture, and when I put
on a little power the accelerator pump in the carb over-enriches the
engine for just a little bit; causing the stumble.

Other pilots and the A&P just tell me to pour on the power a little
slower.

I think I'm going to follow a new SOP. Turn the carb heat off on
mid-final. Reasoning: no carb, esp a warm one is going to ice up in 30
seconds, sets me up better for a go-around, and will prevent this stumble
business (I did test it out at altitude, and it prevents or at least
seriously mitigates the stumble).

thoughts?
T


What's going to happen if you actually do have carb ice which hasn't burned
off by the time you turn carb heat off? I'd much rather attempt a go around
with the carb heat initially on than attempt a go around with the lingering
effects of carb ice.

I have no idea what DA you're talking about, but what you're describing is
trying to correct a problem with the mixture by controlling it with the carb
heat. If you're landing at a high DA airport, you shouldn't have the
mixture full rich. Setting the mixture on downwind is the solution to the
problem. On a 152 or 172 you can also have your hand on the throttle with
your thumb on the carb heat. It should be a natural reaction to push both
in together or push the carb heat in first on a go around.

  #8  
Old September 6th 08, 09:11 PM posted to rec.aviation.piloting
terry
external usenet poster
 
Posts: 215
Default Carb heat: my new policy. Any comments

On Sep 7, 2:58*am, Tman [email protected] wrote:
Flying a lot of 152s and 172s with carb heat lately. *When inbound, I've
been taught to pull the carb heat "on" downwind, hey actually use it as
a power control to slow the plane just a bit mid-field, and then more
importantly, just leave the thing on till clear of the runway and
cleaning up. *No matter what the temp, humidity. *And to have it on at
all times when the RPM is less than the green band. *Kind of a preventative.

A few times I have been coming in on short final and needed a burst of
power due to a sudden downdraft, or needed to pour on a little juice
cause my approach was coming up just a bit short. *Moving the throttle
forward 1/4 to 1/2 inch, i.e. giving it a little juice but certainly not
a go around type of thing, often times I would get a stumble, hicuup,
drop in RPM'S for 2-3 seconds before the horses responded.

Lot of convective turb lately and that power really comes in handy at
times on mid to short final. *Kind of a shocker when the engine doesn't
respond quite nicely.

This has happened on a few birds, especially on hot days. *I think
what's happening is the engine is just too rich, hey I've got the
mixture all the way in, it's hot (air less dense), and it's (way) hotter
with the carb heat on ( air much less dense), all enriching the mixture,
and when I put on a little power the accelerator pump in the carb
over-enriches the engine for just a little bit; causing the stumble.

Other pilots and the A&P just tell me to pour on the power a little slower.

  #9  
Old September 6th 08, 09:21 PM posted to rec.aviation.piloting
Lonnie[_3_]
external usenet poster
 
Posts: 164
Default Carb heat: my new policy. Any comments


"Jon Woellhaf" wrote in message
. ..
I was taught to push in the carb heat with my thumb while advancing the
throttle for a go-around.

"John Smith" wrote in message
...
Tman wrote:

Flying a lot of 152s and 172s with carb heat lately. When inbound, I've
been taught to pull the carb heat "on" downwind, hey actually use it as
a power control to slow the plane just a bit mid-field, and then more
importantly, just leave the thing on till clear of the runway and
cleaning up.


Never heard of this before.

I think I'm going to follow a new SOP. Turn the carb heat off on
mid-final.


Tha't what I've always been taught. Actually, I do it on short final.
There will come the day when you need full power for the go-around. Too
silly if you then have the carb heat on.




Yeah, same here.


  #10  
Old September 7th 08, 04:54 AM posted to rec.aviation.piloting
Robert M. Gary
external usenet poster
 
Posts: 2,767
Default Carb heat: my new policy. Any comments

On Sep 6, 9:58*am, Tman [email protected] wrote:

I think I'm going to follow a new SOP. *Turn the carb heat off on
mid-final. *Reasoning: no carb, esp a warm one is going to ice up in 30
seconds, sets me up better for a go-around, and will prevent this
stumble business (I did test it out at altitude, and it prevents or at
least seriously mitigates the stumble).


Don't put any money on that bet. I've had carbs freeze up on me during
stop-n-goes from the time it takes to kick off the heat to the time it
takes to pour on the coals. The carb can freeze in seconds.

-Robert, CFII
 




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