Aircraft Dynamic Stability

Dynamic stability testing is similar to static stability testing except for adding a time component into the data that we collecting. Learn more at https://tamarackaero.com/insights/category/press-releases Subscribe on YouTube: http://bit.do/tamaracksubscribe Follow us on Twitter: https://twitter.com/tamarackaero Follow us on LinkedIn: https://www.linkedin.com/company/tamarackaero There are four main modes that we are concerned with in dynamic stability testing. The first is the phugoid mode, this is an interaction of pitch moments altitude changes and airspeed changes to create a long gentle climb and decent interaction. The next is the spiral mode which is a long sweeping turn to one direction or the other that tending to complete a full 360. Both of these modes are called long period modes because it takes several minutes for one cycle to complete in some cases. The short period pitch oscillations are the third mode that we look at. These are rocking motions about the pitch axis of the airplane. These cycles can take less than a second to complete, hence short period. The final short period mode that we are going to look at is called Dutch roll. This is an interaction of lift and drag changes at the wingtips causing a rolling and yawing interaction. That looks something like this gentle swaying that you would see an ice skater traveling down from the canal in Amsterdam. Hence the name Dutch roll. Dynamic stability modes are important both the for safety of the pilot in terms of workload and also for passenger comfort. That's why we tend to spend a fair bit of time on them in any flight test program.