Tacoma Narrows Bridge - Addressing Misconceptions

A great paper on how most undergraduate physics texts have described the collapse of the infamous bridge erroneously, over simplifying it to a case of forced resonance. The author of the article, Robert H. Scanlan, describes how the bridge failed due to 'aeroelastic flutter' -Good read. 

http://www.ketchum.org/billah/Billah-Scanlan.pdf

-k

Equation 16.42 - Raymer 4th Edition

I went through Raymer and a couple of other texts (Stengel, Etkin, etc.) and I it's my understanding that the negative term in eqn 16.42 represents 'propeller fin effect' (Etkin eqn.3.9,8) and is destabilizing for a conventional tractor config. 

The term in question, dBp/dB, is analogous to d(alpha)p/d(alpha), which is seen is eqn 16.30 (Raymer) which is the upwash derivative if the engine is in front of the wings. Similarly, dBp/dB, is probably the sidewash derivative wrt to the prop. 

For a single engine tractor configuration the vertical tail is considered far aft, so that dBp/dB is equal to one. I got this value from a colleague, so there is no text I can point to. Raymer doesn't define this term anywhere. 

I'd appreciate  constructive feedback.

-k

F-22 Crashes near Edwards AFB

Yet another crash,

Link 1:

http://www.flightglobal.com/articles/2009/03/25/324350/us-air-force-f-22-raptor-crashes-in-california.html

Link 2:

http://www.airliners.net/aviation-forums/military/read.main/104947/

-k

FedEx MD-11 crash at Narita Intl. Airport

http://news.bbc.co.uk/2/hi/asia-pacific/7958367.stm

Flight Testing - Final Project help

http://web.mit.edu/aeroastro/www/labs/ASL/MODE_AWARENESS/mode_awareness.html

http://www.faa.gov/library/manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-4of7.pdf

Control Systems Basics

A friend pointed me to North Dakota State University's (NDSU) site as a reference for Control Systems fundamentals. 

The course is available for download in .pdf form complete with lecture notes, worked out examples and diagrams.

http://www.ece.ndsu.nodak.edu/~glower/ee461/Lecture_Fa07/

-k

Kalman Filtering

One of the more interesting control systems topics,


"The Kalman filter has two distinct phases: Predict and Update. The predict phase uses the state estimate from the previous timestep to produce an estimate of the state at the current timestep. In the update phase, measurement information at the current timestep is used to refine this prediction to arrive at a new, (hopefully) more accurate state estimate, again for the current timestep."


Basics --> http://www.cs.unc.edu/~welch/media/pdf/maybeck_ch1.pdf


More --> http://en.wikipedia.org/wiki/Kalman_filter


http://www.elo.utfsm.cl/~ipd481/Papers%20varios/kalman1960.pdf


http://www.cs.unc.edu/~welch/media/pdf/kalman_intro.pdf