Flight Instruments
Pitot/Static Instruments
Altimiter
Has an aneroid wafer stack and access to the static port. Aneroid wafers are flexible metal capsules that are sealed with/neutral at standard pressure. When you climb, the altitude is less dense. The static port allows that less dense air to flow into the altimeter's casing, causing the wafer stack to expand because of the difference in pressure in and out of the wafers. The stack is attached to gears that turn the hands on the indicator when the stack moves, giving us our altitude reading.
| Standard Day at Sea Level | |
| Altitude above Mean Sea Level | 0 |
| Pressure | 26.92"Hg |
| Temperature | 59°F (15°C) |
You lose 1"Hg for every 1000ft of altitude climbed
Please note these videos mispronounce some things because they seem to be read by a text-to-speech system but the animations and explanation have been helpful
Supplement: The Pilot Institute - Pressure Altitude vs. Density Altitude: What’s the Difference?
Vertical Airspeed indicator
Tells you if you're climbing or descending.
Pressure from the static port goes into the diaphragm and the casing. The casing has a claibrated (slower/delayed) leak so the pressure in the casing changes at a slower rate from the diaphragm. The pressure differences in the diaphragm and the casing cause the diaphragm to contract or expand, turning the gears that give us our indication.
Please note these videos mispronounce some things because they seem to be read by a text-to-speech system but the animations and explanation have been helpful
Airspeed Indicator
Tells you what just the ram air pressure from the pitot tube is by comparing it with static pressure.
Static pressure is included with the ram air pressure from the pitot tube, so it
It uses a diapragm inside a casing where the static pressure is in the casing. The pitot tube feeds/expands the diaphragm.
Has a drain hole at the back that doesn't affect the formula other than helping the intake to stay unblocked
Imaginary formula V = D+S-S
- V: indicated airspeed
- D: dynamic/impact/ram air
- S: static air pressure
- +S comes from the static port
- -S is neutralized with the drain hole at the back of the pitot tube
Please note these videos mispronounce some things because they seem to be read by a text-to-speech system but the animations and explanation have been helpful
less accurate at higher altitudes and temperatures
Pitot/Static System Errors
| Airspeed | Altimiter | Vertical Speed | |
|---|---|---|---|
| Front of pitot blocked, static clear | reads 0 | No effect | No effect |
| Front and drain of pitot blocked | acts as an altimeter | No effect | No effect |
| Pitot clear, static blocked | much higher airspeed | frozen in place | reads 0 |
Gyroscopic Instruments
00:47:00 Ther's an engine driven vacuum pump moving gyroscopes in the system
Rigitity in Space
As long as a gyroscope is spinning, it will be able to stay in a "fixed" position
Heading indicator
Gimbal rotation
The airplane is spinning around the
Gyroscopic procession
Why do we care about this in the instruments
Turn Coordinator
Candted Gyro
Operates from electrical power The ball is just from gravity in fluid
Skid is tokyo drifting, you can end up in a spin On base to final you sometimes encourage a skid Also taking off and turning crosswind is when you'll spin
Uses rigity in space
Magnetic Compass
True north and magnetic north -> Magnetic variation
UNOS Undershoot north, overshoot south
ANDS Accellerate North Decelerate South
Magnetic deviation The metal in the plane interferes with the metal in the compass
Airplanes have a compass card that
VOR
Very High Frequency Omnidirectional Range VOR Station
After "Tuning in a VOR" You can fingure out where in relation to the VOR you are
Pulsing and Sweeping signal
Course Deviation Indicator
If you did dual VOR navigation you'd ude two CDIs
You get the VOR frequencies from your chart
Turn the OBS knob to change the heading, tune in your CDI through OBS
Errors
Scalping - it will swing back and forth. you can still use it by averaging the center of where it's swinging
The US has a VOR "minimum operational network" where you could
You can use DME for measuring distance from a VOR
Distance Measuring Equipment
DME measures distance in slant range distance Not good at it's job when you're close and high. Accurate when you're low and far away
Do we need to know more than abode?
A VOR has DME most of the time if it has DME at all. twin oakes planes have GPS instead of DME
Horizontal Situation Indicator HSI
Usually wont have the analog version of this in most (Twin Oaks) cesnas The cesnas have a G5
Electronic instruments
Combines your entire 6pack into one instrument
magnetometer
Heading comes from magnetometer - located in the tail, the wing or in cesnas the strut. It measures the change in the flow of an electronic current
Air Data computer
rv12s 448 35H
Those iwthout an air temperature probe uses ... something else. Without the probe it cant calculate true airspeed
Attitude and Headeing Reference System
Combination of magnitometer, accelerometer and a fake gyroscope In the g5s it
Air inertia sensor ..??