Thursday, January 19, 2017

XPlane 10 Data.txt -> XPlane 10 [File] .fdr

When flying an aircraft in XPlane, the flight data is recorded to a file name Data.txt.  Also, if you wish to playback data, you can save a .rep replay file and play that file back.  However you cannot playback Data.txt.  You can however play back a file produced in XPlane's .fdr file format.  However, there is no Data.txt to [file].fdr translation program available by XPlane, nor is there is way to save a XPlane recording into their own .fdr format.

This above latter statement is why the xdata2xfdr utility has been created.  It's a python script, and it simply converts XPlane Data.txt files to the XPlane FDR format.

The script only handles the basic fields now.  Feel free to contribute to the project, if you wish.

Note that the script is designed for XPlane 10 and may not work for XPlane 11.

Again, the utility is on GitHub: xdata2xfdr

Wednesday, January 18, 2017

FAA Digital Obstacle File (DOF) and MongoDB

Siats is a utility to load the FAA Digital Obstacle File (DOF) into your own MongoDB database.  

This siats project contains three python utilities in support of the FAA Digital Obstacle File. The main script loads the DOF into a MongoDB collection. The remaining two scripts simply count the number of obstacles and the other displays the obstacles using Matplotlib.

The dependencies are as follows.


You will need the following to run the scripts
  • Python 3.5
  • Pymongo (MongoDB Python Driver)
  • Your own MongoDB Server
  • MongoDB Connection info (i.e., URL, Username, Password)
  • Current DOF files (assuming the format hasn't changed from 120619 release)
  • Matplotlib and dependencies (to support the visualization script)


Visualizing the sets of obstacles by states is easy with the script, as shown here for Georgia...

def main():

# AL, AK, AZ, AR, CA, CO, CT, DE, DC, FL, GA, HI, ID, IL, IN, IA, KS, KY, LA,
# ME, MD, MA, MI, MN, MS, MO, MT, NE, NV, NH, NJ, NM, NY, ND, OH, OK, OR, PA,
# RI, SC, SD, TN, TX, UT, VT, VA, WA, WV, WI, WY

Monday, January 16, 2017

Estimating Weights in the Preliminary Design Process of Rotorcraft

Various methods have been established in the past to determine estimate weights of rotorcraft components and groups of components.  These weight values are used by weight engineers to supplement the preliminary design process of rotorcraft. Some of the best resources in these regards are as follows.

This weekend, I took some time to realize these methods through a Java Utilities Class called Rweu (i.e., Rotorcraft Weight Estimates Utility).  The code for Rweu is on GitHub.

Before you get too excited about this Rweu utility, there are some limitations...
  • The utility is based on an existing database of helicopter component weights, and multiple linear regression thereof... I do not have the database.
  • The utilities are best suited to be constantly evolved and improved... I believe the equations are decades old.
So then why bother coding the methods up at all?  Well, I can think of a few reasons...
  • With the proper effort and collaboration, the methods, database (if acquirable), etc. could be brought up to current standards and could be utilized.
  • The book by Prouty is an excellent learning resource, and this Rweu utility class complements the book well.
  • Rweu provides an additional resource for weight engineers.
  • The observed methodology of weight estimates can be applied to other spaces, such as UAVs.
So then, what are you 'weighting' for... lol... get working on your rotorcraft weight estimates. :)  And if you missed it, here is the utility class on GitHub.

Friday, January 13, 2017

Harmonics on the Guitar

1/4 (5th fret), 1/3 (7th fret), 1/2 (12th fret) and 2/3 (19th fret) lengths of the guitar from the nut to the saddle will give you some nice sounding harmonics.

Thursday, January 12, 2017

Windmill Brake State (WBS) Definitions


  • Windmill brake state is the state of the rotor in greater than autorotative descent rates. -- VR Veteran Poster

Windmill brake state - At very high rates of descent, the airflow is almost entirely up through the rotor system. The rotor system is acting similar to a windmill. It is extracting more energy from the air than is required for flight. It is not a normal operating state for the rotor system; some energy must be extracted to prevent a rotor overspeed. This can usually be accomplished by increasing collective pitch, which adds more drag to the system. -- From Army FM 1-203 (Oct 88)

The article focuses on the windmill-brake state prevalent among helicopters. It mentions that such state is where the vertical descent of the helicopter is very high causing the rotor to absorb much energy from the passing air. It adds that helicopters flying in the said state is converting potential energy to kinetic energy. -- The Windmill-brake State

If the tunnel upflow is increased to the point where it is higher than the rotor-induced velocity, both the local flow at the rotor and the flow in the remote field are up; there is a well-behaved wake above the rotor, and the momentum concepts can again be used.  This condition is known as the windmill brake state.  -- Helicopter Performance, Stability, and Control.

At rates of descent in excess of vih the vortex ring rises above the disk and the rotor is said to be operating in the turbulent windmill-brake state. - The windmill-brake state by Helicopter Test and Evaluation

Beyond the vortex-ring conditions exists the windmill-brake state, in which the rotor derives its energy from the air. The flow is upward through the rotor and the thrust is produced by slowing down the air as it passes through the rotor disc. The boundary condition between the vortex-ring and windmill-brake states is the condition where the upward flow of air is brought to rest at the rotor disc. This condition of no flow through the disc is referred to as ideal autorotation.  -- Helicopter Behaviour in the Vortex-Ring Conditions By W. STEWART, B.Sc.

Wednesday, January 11, 2017

Anna Shannon. Yorkshire Song.

When heather’s bloom has faded long and turned to brown
When pheasant chides his bright alarm
When rolling mist the valley shrouds in silent arms
Once more I know this place to be my home

I heard the curlew cry today from windswept heath
A plaintive call on rising wing
And as I watched from ragged lines of weathered trees
My heart stirred from her place to go with him

There’s not one thing I would not give to be as he
To circle here in joyous flight
And on these moors my life to live to simply be
My spirit to go on in hill and scree

I wish that I could write a song that had no words
Of beauteous things and journeys run
For many is the time I’ve tried and tales begun
But with beauty such as this the words won’t come

When heather’s bloom has faded long and turned to brown
When pheasant chides his bright alarm
When rolling mist the valley shrouds in silent arms
Once more I know this place to be my home

Monday, January 9, 2017

Free Java 8 Pocket Guide Give Away (10 Books)

When the total number of page views of this blog reaches 500,000...

I will give away ten free Java Pocket Guides to random readers that

comment below stating why they would like to have the guide.

Good Luck.