7/28/2019 Aircraft Heat Valve
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In aircraft
In light aircraft, the carburetor heat is usually manually
controlled by thepilot. The diversion of warm
air into the intake reduces the available power from the engine
for three reasons: thermodynamic
efficiency is slightly reduced, since it is a function of the
difference in temperature between the
incoming and exhaust gases; the quantity of air available for
combustion inside the cylinders is
reduced due to the lower density of the warm air; and the
previously-correct ratio of fuel to air is upset
by the lower-density air, so some of the fuel will not be burned
and will exit asunburned
hydrocarbons. Thus the application of carb heat is manifested as
a reduction in engine power. If ice
has built up, there will then be a gradual increase in power as
the air passage is freed up by the
melting ice. The amount of power regained is an indication of
the severity of ice buildup.
It must be kept in mind that the ingestion of small amounts of
water into the engine following melting
in the carburetor may cause an initial period of rough running
for as much as one or two minutes
before the power increase is noted. Again, the pilot will note
this as evidence that icing conditions are
present. However, more than one pilot, when confronted with a
rough running engine has mistakenly
turned the carburetor heat back off, thereby exacerbating the
situation.
Applying carb heat as a matter of routine is built into numerous
in-flight and pre-landing checks (e.g.
seeBUMPHandGUMPS). In long descents, carb heat may be used
continuously to prevent icing
buildup; with the throttle closed there is a large pressure (and
therefore temperature) drop in the
carburetor which can cause rapid ice buildup that could go
unnoticed because engine power is not
used. In addition, the exhaust manifold cools considerably when
power is removed, so if carb icing
occurs there may not be heat sufficient to remove it. Thus most
operationalchecklistscall for the
routine application of carb heat whenever the throttle is closed
in flight.
Usually, theair filteris bypassed when carb heat is used. If the
air filter becomes clogged (with snow
or ice), using carb heat allows the engine to keep running.
Because using unfiltered air can cause
engine wear, carb heat usage on the ground (where dusty air is
most probable) is kept to a minimum.
Altitude has an indirect effect on carburetor ice because there
are usually significant temperature
differences with altitude.Cloudscontain moisture, and therefore
flying through clouds may
necessitate more frequent use of carb heat.
The intake air of an aircraft engine equipped with
asuperchargeris heated through compression, so
the air entering the throttle body is already warmed enough that
carb heat is unnecessary.
In aircraft
In light aircraft, the carburetor heat is usually manually
controlled by thepilot. The diversion of warm
air into the intake reduces the available power from the engine
for three reasons: thermodynamic
efficiency is slightly reduced, since it is a function of the
difference in temperature between the
incoming and exhaust gases; the quantity of air available for
combustion inside the cylinders is
http://en.wikipedia.org/wiki/Aviatorhttp://en.wikipedia.org/wiki/Aviatorhttp://en.wikipedia.org/wiki/Aviatorhttp://en.wikipedia.org/wiki/Unburned_hydrocarbonhttp://en.wikipedia.org/wiki/Unburned_hydrocarbonhttp://en.wikipedia.org/wiki/Unburned_hydrocarbonhttp://en.wikipedia.org/wiki/Unburned_hydrocarbonhttp://en.wikipedia.org/wiki/BUMPHhttp://en.wikipedia.org/wiki/BUMPHhttp://en.wikipedia.org/wiki/BUMPHhttp://en.wikipedia.org/wiki/GUMPShttp://en.wikipedia.org/wiki/GUMPShttp://en.wikipedia.org/wiki/GUMPShttp://en.wikipedia.org/wiki/Checklisthttp://en.wikipedia.org/wiki/Checklisthttp://en.wikipedia.org/wiki/Checklisthttp://en.wikipedia.org/wiki/Air_filterhttp://en.wikipedia.org/wiki/Air_filterhttp://en.wikipedia.org/wiki/Air_filterhttp://en.wikipedia.org/wiki/Cloudhttp://en.wikipedia.org/wiki/Cloudhttp://en.wikipedia.org/wiki/Cloudhttp://en.wikipedia.org/wiki/Turbo-superchargerhttp://en.wikipedia.org/wiki/Turbo-superchargerhttp://en.wikipedia.org/wiki/Turbo-superchargerhttp://en.wikipedia.org/wiki/Aviatorhttp://en.wikipedia.org/wiki/Aviatorhttp://en.wikipedia.org/wiki/Aviatorhttp://en.wikipedia.org/wiki/Aviatorhttp://en.wikipedia.org/wiki/Turbo-superchargerhttp://en.wikipedia.org/wiki/Cloudhttp://en.wikipedia.org/wiki/Air_filterhttp://en.wikipedia.org/wiki/Checklisthttp://en.wikipedia.org/wiki/GUMPShttp://en.wikipedia.org/wiki/BUMPHhttp://en.wikipedia.org/wiki/Unburned_hydrocarbonhttp://en.wikipedia.org/wiki/Unburned_hydrocarbonhttp://en.wikipedia.org/wiki/Aviator
7/28/2019 Aircraft Heat Valve
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reduced due to the lower density of the warm air; and the
previously-correct ratio of fuel to air is upset
by the lower-density air, so some of the fuel will not be burned
and will exit asunburned
hydrocarbons. Thus the application of carb heat is manifested as
a reduction in engine power. If ice
has built up, there will then be a gradual increase in power as
the air passage is freed up by the
melting ice. The amount of power regained is an indication of
the severity of ice buildup.
It must be kept in mind that the ingestion of small amounts of
water into the engine following melting
in the carburetor may cause an initial period of rough running
for as much as one or two minutes
before the power increase is noted. Again, the pilot will note
this as evidence that icing conditions are
present. However, more than one pilot, when confronted with a
rough running engine has mistakenly
turned the carburetor heat back off, thereby exacerbating the
situation.
Applying carb heat as a matter of routine is built into numerous
in-flight and pre-landing checks (e.g.
seeBUMPHandGUMPS). In long descents, carb heat may be used
continuously to prevent icingbuildup; with the throttle closed
there is a large pressure (and therefore temperature) drop in
the
carburetor which can cause rapid ice buildup that could go
unnoticed because engine power is not
used. In addition, the exhaust manifold cools considerably when
power is removed, so if carb icing
occurs there may not be heat sufficient to remove it. Thus most
operationalchecklistscall for the
routine application of carb heat whenever the throttle is closed
in flight.
Usually, theair filteris bypassed when carb heat is used. If the
air filter becomes clogged (with snow
or ice), using carb heat allows the engine to keep running.
Because using unfiltered air can cause
engine wear, carb heat usage on the ground (where dusty air is
most probable) is kept to a minimum.
Altitude has an indirect effect on carburetor ice because there
are usually significant temperature
differences with altitude.Cloudscontain moisture, and therefore
flying through clouds may
necessitate more frequent use of carb heat.
The intake air of an aircraft engine equipped with
asuperchargeris heated through compression, so
the air entering the throttle body is already warmed enough that
carb heat is unnecessary.
http://en.wikipedia.org/wiki/Unburned_hydrocarbonhttp://en.wikipedia.org/wiki/Unburned_hydrocarbonhttp://en.wikipedia.org/wiki/Unburned_hydrocarbonhttp://en.wikipedia.org/wiki/Unburned_hydrocarbonhttp://en.wikipedia.org/wiki/BUMPHhttp://en.wikipedia.org/wiki/BUMPHhttp://en.wikipedia.org/wiki/BUMPHhttp://en.wikipedia.org/wiki/GUMPShttp://en.wikipedia.org/wiki/GUMPShttp://en.wikipedia.org/wiki/GUMPShttp://en.wikipedia.org/wiki/Checklisthttp://en.wikipedia.org/wiki/Checklisthttp://en.wikipedia.org/wiki/Checklisthttp://en.wikipedia.org/wiki/Air_filterhttp://en.wikipedia.org/wiki/Air_filterhttp://en.wikipedia.org/wiki/Air_filterhttp://en.wikipedia.org/wiki/Cloudhttp://en.wikipedia.org/wiki/Cloudhttp://en.wikipedia.org/wiki/Cloudhttp://en.wikipedia.org/wiki/Turbo-superchargerhttp://en.wikipedia.org/wiki/Turbo-superchargerhttp://en.wikipedia.org/wiki/Turbo-superchargerhttp://en.wikipedia.org/wiki/Turbo-superchargerhttp://en.wikipedia.org/wiki/Cloudhttp://en.wikipedia.org/wiki/Air_filterhttp://en.wikipedia.org/wiki/Checklisthttp://en.wikipedia.org/wiki/GUMPShttp://en.wikipedia.org/wiki/BUMPHhttp://en.wikipedia.org/wiki/Unburned_hydrocarbonhttp://en.wikipedia.org/wiki/Unburned_hydrocarbon
