When Fuel Meets Air - Savvy-EAA Webinar
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Where Fuel Meets Air Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 1 Your presenter… Mike Busch A&P/IA Columnist — AOPA PILOT magazine Instructor — EAA Webinars Podcaster — Ask the A&Ps (AOPA) National Aviation Maintenance Technician of the Year (2008) President — Savvy Aviation, Inc.
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Transcript of When Fuel Meets Air - Savvy-EAA Webinar
Where Fuel Meets Air
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 1
Your presenter…
Mike Busch A&P/IAColumnist — AOPA PILOT magazine
Instructor — EAA Webinars
Podcaster — Ask the A&Ps (AOPA)
National Aviation Maintenance Technician of the Year (2008)
President — Savvy Aviation, Inc.
Mo 1000 #7 The EGT MythMo 1300 #7 How Healthy Is Your Engine?Tu 0830 #7 To TBO and Beyond…Tu 1000 #7 Leaning The Right WayTu 1300 #7 Destroy Your Engine in 1 MinuteWe 0830 #7 Cylinder Break-In: Do It RightWe 1130 #7 What Is Preventive Maintenance?We 1430 #7 Cylinder Work: Risky BusinessFr 0830 #7 It’s BafflingFr 1000 #7 Where Fuel Meets AirFr 1300 #7 Benefits of Running OversquareSa 1000 #7 How Mags Work…and FailSa 1300 #7 Predictive MaintenanceWhere Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 2
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 3
to receive my monthly e-newsletterand weekly maintenance stories
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 4
Spark Ignition
Compression Ignition (Diesel)
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 5
Spark Ignition
Compression Ignition (Diesel)
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 6
Spark Ignition
The process of creating a combustible air-fuel mixture is called “metering”
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 7
LOP ROP
Mixture too lean to burn
Mixture too rich to burn
Mixture too rich
to produce power
Power
Bes
t ec
onom
y
Bes
t po
wer
Sto
ichiometr
ic(c
hemically c
orre
ct)
18:1 16:1 14.7:1 12:1 8:1 5.5:1
Air-Fuel Ratio by weight
Best Economy (16:1)
Stoichiometric (14.7:1)
Best Power (12:1)
Mixtures we actually use
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 8
car·bu·re·tor/ˈkärb(y)əˌrādər/noun
a device in an internal combustion engine for mixing air with fuel
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 9
Earliest carburetors were developed in the 1860sThey were “evaporative” carburetors that used drips, wicks, and other mechanisms for combining fuel with air by means of evaporation of the volatile fuel
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 10
Earliest carburetors were developed in the 1860sThey were “evaporative” carburetors that used drips, wicks, and other mechanisms for combining fuel with air by means of evaporation of the volatile fuel
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 11
Early 20th
century brought development of “proportioning” carburetors
These were capable of measuring the volume of air flowing into the engine and determining the proper amount of fuel required
Claudel-Hobson, Beardmore, Zenith, Bendix-Stromberg…
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 12
Marvel-Schebleraircraft carburetor is the most common in modern GA aircraft
Invented by George Scheblerand Burt Pierce (the MMO guy!)
Originally used in Indy race cars from 1911 to 1935
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 13
The Marvel-ScheblerCarburetor Company changed ownership numerous times…
LLC
Since 2011
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 14
“Updraft” Carburetor
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 15
“Updraft” Carburetor
Float ChamberThrottle Body
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 16
Carburetor float chamber works like a toilet tank
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 17
Throttle body allows airflow to engine to be regulated by means of a throttle valve
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 18
A venturi in the throttle body creates low pressure (suction) that varies with airflow
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 19
Venturi suction pulls fuel through the nozzle into the air stream
The volume of fuel is proportionalto the volume of air
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 20
Mixture control
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 21
“Idle circuit” provides additional fuel when engine is at idle
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 22
The idle circuit has a needle valve that allows adjustment of idle mixture
Proper adjust-ment results in a 25-50 RPM rise when engine is leaned at idle
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 23
The idle circuit has a needle valve that allows adjustment of idle mixture
Proper adjust-ment results in a 25-50 RPM rise when engine is leaned at idle
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 24
Accelerator pump provides extra fuel when the throttle is opened quickly in order to prevent the engine from stumbling
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 25
Although Marvels are “proportioning” carbs, they meter fuel volumein proportion to air volume
Since air-fuel ratio is by weight and not volume, it’s still necessary to manually lean as altitude increases and air density decreases
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 26
They don’t work well in negative-G maneuvers (e.g., inverted flight)
They’re susceptible to carb icing in the venturi and throttle butterfly due to evaporative cooling by fuel
It’s tricky to get them to work with turbocharged engines
Float-type carburetors have several inherent limitations…
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 27
Carb iceis not nice!Certain engines are especially vulnerable
(e.g., Continental O-470-series)
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 28
One solution:
“pressure carburetor”
(a.k.a. “throttle body injection” or “TBI”)
Stromberg PS
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 29
Fueldischarge nozzle is downstreamof the venturi and throttle butterfly (so no icing)
Stromberg PS
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 30
Fuel pressure regulator
(where all the magic happens)
Stromberg PS
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 31
A BC D
Air flow force
Fuel flow force
Fuel metering
valve
Impact tubes
Venturi suction
Fuel
To nozzle
Stromberg PS
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 32
Rotec TBI
Ellison TBI
Several much simpler TBI units are available for experimentals
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 33
Induction system plumbing…
Twists and turns cause centrifugal separation of atomized fuel droplets, therefore uneven mixture distribution…
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 34
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 35
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 36
Intake port fuel injection
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 37
Intake port fuel injection
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 38
Bendix/RSA system
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 39
Impact scoop
Venturi suction
Throttle valve
Bendix/RSA system
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 40
Four-chamber fuel pressure
regulator
Bendix/RSA system
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 41
Flow divider
Fuel nozzles
Bendix/RSA system
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 42
Mixture control valve
Bendix/RSA system
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 43
Automatic mixture control
Bendix/RSA system
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 44
Continentalsystem
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 45
Continentalsystem
Engine-driven fuel pump
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 46
Continentalsystem
Fuel control
Throttle body
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 47
Continentalsystem
Metered fuel pressureis a function of: • Engine RPM• Throttle position• Mixture control position
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 48
Continentalsystem
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 49
Continental PowerLink FADEC
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 50
Continental PowerLink FADEC
Mo 1000 #7 The EGT MythMo 1300 #7 How Healthy Is Your Engine?Tu 0830 #7 To TBO and Beyond…Tu 1000 #7 Leaning The Right WayTu 1300 #7 Destroy Your Engine in 1 MinuteWe 0830 #7 Cylinder Break-In: Do It RightWe 1130 #7 What Is Preventive Maintenance?We 1430 #7 Cylinder Work: Risky BusinessFr 0830 #7 It’s BafflingFr 1000 #7 Where Fuel Meets AirFr 1300 #7 Benefits of Running OversquareSa 1000 #7 How Mags Work…and FailSa 1300 #7 Predictive MaintenanceWhere Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 51
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 52
to attend my free monthly maintenance webinars
on the first Wednesday of each month
(sponsored by EAA and Aircraft Spruce)
to participate in my free monthly podcast “Ask the A&Ps” with my colleagues Colleen Sterling A&P/IA and Paul New A&P/IA sponsored by AOPA
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 53
to receive my monthly e-newsletterand weekly maintenance stories
Copyright 2021 Savvy Aviator, Inc. 54
I’m happy to autograph your book
Where Fuel Meets Air
Questions?
Contact info:
Where Fuel Meets Air Copyright 2021 Savvy Aviator, Inc. 55
.com
To receive my monthly newsletter and weekly maintenance stories,
text “SAVVY” to 33777
