Cessna's and Gyros vs Accelerometers
I fly a small Cessna. As a student pilot I once asked a lot of silly questions. One was, how does the fuel stay in both wings evenly? Sometimes you go fly and 'orbit' something on the ground for an hour in the same direction. So the fuel should all be in the lower wing as it cross-feeds between them.
The answer was obvious, and that is when you're flying the airplane is pulling positive Gs. So when you bank, the horizontal component of lift which is like centrifugal force holds the fuel as if the airplane were still level. That may not be the best explanation, but you can loop an airplane with a cup of water and it will stay just like it was on the ground without spilling. In the back of my mind I had always imagined being stuck in really bad weather with zero vis. while flying, and losing multiple instruments. I always though hey, why not just hang something from the ceiling (like fuzzy dice on a rear view in a car) and use that as an indicator of your attitude? Well, that wouldn't work either, just like the fuel it wouldn't read. So to make a long story even longer, I learned everything I possibly could about how the attitude indicator works. The principle of rigidity in space. Gyroscopes. Neat stuff.
I've had one of these for years - http://www.parallax.com/Store/Sensors/AccelerationTilt/tabid/172/CategoryID/47/List/0/SortField/0/Level/a/ProductID/585/Default.aspx but I never took it flying because it is not a gyroscope and I assumed that it wouldn't be able to tell me my attitude just like the water in the cup. However, I see people building a bunch of UAS autopilots with it. Am I missing something?
Also does this http://www.parallax.com/Store/Sensors/AccelerationTilt/tabid/172/CategoryID/47/List/0/SortField/0/Level/a/ProductID/778/Default.aspx have an actual mechanical gyro inside that would be more accurate?
I really want to take some projects flying
Thanks.
The answer was obvious, and that is when you're flying the airplane is pulling positive Gs. So when you bank, the horizontal component of lift which is like centrifugal force holds the fuel as if the airplane were still level. That may not be the best explanation, but you can loop an airplane with a cup of water and it will stay just like it was on the ground without spilling. In the back of my mind I had always imagined being stuck in really bad weather with zero vis. while flying, and losing multiple instruments. I always though hey, why not just hang something from the ceiling (like fuzzy dice on a rear view in a car) and use that as an indicator of your attitude? Well, that wouldn't work either, just like the fuel it wouldn't read. So to make a long story even longer, I learned everything I possibly could about how the attitude indicator works. The principle of rigidity in space. Gyroscopes. Neat stuff.
I've had one of these for years - http://www.parallax.com/Store/Sensors/AccelerationTilt/tabid/172/CategoryID/47/List/0/SortField/0/Level/a/ProductID/585/Default.aspx but I never took it flying because it is not a gyroscope and I assumed that it wouldn't be able to tell me my attitude just like the water in the cup. However, I see people building a bunch of UAS autopilots with it. Am I missing something?
Also does this http://www.parallax.com/Store/Sensors/AccelerationTilt/tabid/172/CategoryID/47/List/0/SortField/0/Level/a/ProductID/778/Default.aspx have an actual mechanical gyro inside that would be more accurate?
I really want to take some projects flying
Thanks.
Comments
To make a good autopilot you will need both accelerometers and gyros.
An example, the HoverFly Sport board has gyros only and it works well for stabilizing but will not auto level. The HoverFly Pro board has gyros and accelrometers so it is good for stabilizing and keeping track of which way is up.
Mechanical gyro? It depends on what you mean by mechanical. It does not have a spinning gyro in it. It more likely has something similar to a tuning fork that vibrates at a high frequency.
I want an attitude indicator though, no auto-pilot. It would be fun to put a Propeller auto-pilot into an airplane but unfortunately I rent and cannot. I'm slowly talking them into Parallax based GPS data loggers for flight reviews. How cool would it be to eject your USB thumb drive from the panel, go inside the classroom and get debriefed on maneuvers while looking at your route of flight? I love it.