This new column will feature a brief description, photo or video, and/or reference that talks about a Flight Test Technique that students at USAF Test Pilot School are currently learning. It’s an alphabetical list of FTTs together with a chronological account of what future test pilots and flight test engineers are doing right now. It will complement the previous Friday’s FTT tweets as well.
What is a doublet?
1. An elementary open loop maneuever performed in a single axis of motion.
2. A flight control input used in flying qualities flight test to excite an aircraft mode of motion. Here is a video of a Bonanza doing a rudder doublet to excite the lateral directional modes of motion.
3. A symmetric input in both directions–for example, you could push the stick forward one inch then pull the stick back (past neutral) one inch and then return to center.
Here is a time history plot of the response to a doublet performed using rudder pedals, for example.
What is a singlet?
An asymmetric flight control input in one direction. For example, you could push the stick forward one inch then then return to center.
Here is a time history plot of the singlet – the flight control input (elevator) is the third line, and the other lines are the aircraft response.
This post summarizes references and #FTT tweets from the previous Friday. What is #FTT Friday?
Each Friday, @FlightTestFact will deliver examples, definitions, and explanations of flight test techniques for the entire day. You can view these tweets by searching for #FTT and #flighttest as depicted below. You can also click on the picture below to be taken to the twitter search results. What FTT would you like to know more about?