Competitive Soaring: Brigliadori Distilled

As presented at the SSA Convention in Reno, NV I have attached my presentation below.  It is a distillation of Leo and Ricky Brigliadori's book Competing in Gliders.  Additionally I am working on a version that includes the audio of my talk.  Please feel free to email me with your questions and comments so that we can all continue to learn how to fly faster.

Keep flying, especially with the stick full forward.
Michael "BK"


(To view the presentation, click the Play button in the window below, select MORE, then FULL SCREEN in the lower right corner)

Competitive Soaring: Brigliadori Distilled on Prezi

Short post today. This link, is one of the best, concise descriptions of the basics of ridge soaring I thought it deserved a post.

Keep soaring, closer to the ridge the better. Michael

Racing the Libelle

I recently gave a presentation at the 2011 Experimental Sailplane Homebuilders Workshop in Tehachapi, CA on the modifications I have made to my Libelle 201b and some of my experiences racing it in regional and national contests. I would also like to welcome all the visitors from the Cafe Foundation Blog. Big thanks to Dean Segler for linking back to my Blog!

Racing the Libelle

Until my next post...Keep Soaring
(it's almost wave season!)
Michael

Breeze Fronts

This week we had some local fires that were started by dry lightning. Overall a bad thing but it did provide an opportunity to capture the daily afternoon phenomena of the breeze front (AKA Sea Breeze Front) pushing through the Tehachapi, CA valley on it's way to spilling into the desert floor near Mojave, CA.

The breeze front is the cool stable air from the San Joaquin Valley pushing east as the thermals in the desert start to die and no longer act as a thermal block to the normal west to east trade winds.

The breeze front, though itself stable, promotes thermal development by providing relatively cool air to help the last little bit of heated air in the super adiabatic layer to separate from the ground and form thermals. Thermals form at the boundary of the cool stable air and warm unstable air.

So here is a picture of what I am talking about. You can see the cool stable air moving in the from the right, marked by the smoke it carries with it, and the clear unstable air on the left. The Raged cu in the upper right are normal indicators of the thermals produced by breeze fronts.



See Reichmann, "Cross Country Soaring" Pages 27-29 for more information.

I hope you now better understand a common soaring weather phenomena.

Keep soaring,
Michael

Calcuating Trigger Time

The last post covered the process of calculate trigger temperature and the mechanics of the atmosphere that are underway as the day heats up and thermals start. Today's post will cover how to estimate what time the surface temperature will reach trigger temperature and will also cover a few other tips related to trigger temperature.

To find the estimated trigger time first recall this plot from the last post:
It turns out that the heat required to eliminate the ground inversion is proportional to the area of the triangle formed by the temperature profile (shown above as the area shaded with dashed lines). So, first calculate the area under the temperature profile, this can be done by copying the plot onto graph paper and counting the squares or by simple geometry; the area of a triangle is 1/2 * base * height. For plots of this type the y axis might be in milibars, you will want to convert milibars into feet. The x axis is temperature. That means the area calculation you have done will result in units of (degree*ft). Which is handy because the chart below, which shows the available heating from the sun just happens to be in degree*ft!

This chart is for a latitude of 45deg, if your latitude is greater/less move/down up 1/2 hour for every 5deg difference in latitude. This chart allows us to predict when the air will have been heated enough to over power the ground inversion. Note that the above chart is for clear skies, cirrus, fog, smoke or any other sun blocker can reduce the about of energy reaching the ground and should be accounted for.

The other method, which is much more user friendly is to rely on your local weather station predictions for the temperature as throughout the day. You can always supplement this information with temperature readings of you own. I glued a thermometer to my wing wheel so when i'm waiting to launch I can monitor the rise in temperature and know if it is rising faster or slower than predicted and adjust my launch time accordingly.

All of these methods help you become more aware of how the soaring day starts and how to position yourself to start your flight on time and get the most of the soaring day for those long tasks. Until next time...

Keep soaring,
Michael