April 30, 2013

Flying the ASH-25 with Kempton Izuno

Getting the chance to fly dual cross country with an experienced pilot in a real XC machine like an ASH-25 is a rare opportunity, so when I got the call from Kempton Izuno asking if I was available to attempt a XC mission from Williams Soaring Center to Crater Lake, OR, the only answer possible was, “Yes!”.  The weather was predicted to be very good Friday thru Sunday in the Eastern Sierra, where I normally fly; Kempton was planning the flight in a slightly different air mass to the west over the coastal ranges in Northern California.  I could have made the 6 hour drive to Williams on Friday during the day, but I decided to take advantage of the great local soaring weather instead and made a 400km racing flight from California City.  It made the drive that evening tough, arriving at Williams at 11:30pm, but the bunk house was ready to go when I arrived and I was asleep before my head hit the pillow.

I woke up the next morning to the wonderful smell of pancakes, bacon, and coffee emanating from the bunkhouse kitchen.  I got dressed and found Kempton; we discussed the plan for the day and weather forecast  over breakfast.

The forecast had been drying out all week leading up to the flight, decreasing the probability of making the jump from the coastal range to the Cascades, taking Crater Lake out of possible turn points.  However the weather would still support a nice flight up the Mendocino Mountain Range and give me a chance to pick up tips on techniques and tactics from Kempton.

The following is a summary of the key points I picked up from Kempton’s flying that others may find useful.  A little background, Kempton is not a racing pilot; he is a very experienced and exceptional distance pilot and has developed his techniques and tactics over more than 30 years of starting early, coming home late, and flying for distance.

1)      Kempton makes small and aggressive corrections when centering thermals.  When asked which thermal centering technique he uses, i.e. Decrease Bank as Lift Increases, he responded by saying he doesn't have a well-defined mechanical technique, he relies on feeling the lift and making the necessary corrections.

2)      Kempton emphasized staying to the high ground; if you fall off the upper ridge get to the next lower ridge as fast as possible.  What was interesting to me was how much this rule dictated the path we took, we made fairly large off heading deviations to follow all the little ridges, spines, and plateaus.  This allowed us to press further along our course earlier in the day.  Kempton mentioned that these techniques were taught CNVV at St. Auban, France.

3)      When we were >300’ over a ridge Kempton took a path that favored the upwind side of the ridge over the sun side.  It seemed to work and allowed for good protection from getting low on the lee side.

4)      Kempton was always reminding me to look up.  The Cu were small, wispy, and cycling quick; often we were in a thermal climbing in good lift only to find a Cu forming slightly to one side of our climb, a little adjustment and we found a better climb. Kempton developed these techniques throughout the years and were confirmed through conversations with Brian Spreckley and Peter Alexander.

5)      On our way home, Kempton discussed using the outlets of all the little valleys along the mountain range as potential sources for a late evening thermal.  Thermal triggers, caused by catabatic winds creating a mini convergence ‘finger’ extending into the flatlands from the outlet of mountain valleys can often be the key to getting home. A note from Kempton: This technique was picked up from Stefan Leutenegger, a top Swiss pilot.  Stefan said this is a common occurrence in the Swiss Alps.
Here are Kempton’s thought on our flight:
In regards to finding a 7 knot thermal east of the peak at Yolla Bolla, “I found it puzzling why the cu was over the bowl, not the peak. The winds had been basically zero, so I concluded that with nothing to push the thermals one way or the other up the sides of a bowl, they would pop from inside the bowl. “
T15 (peak) had lift right over it, but after that, and in the low ridge area north of T15 to Hayfork Peak and Buckhorn, the shreds were not over the peaks, but rather on the sun side slope about half to one mile away from the peaks.  We saw a shred east of Hayfork peak so went for that and climbed up to 9k, then saw another shred at Buckhorn (S of the peak) and went for that. By this time it was 3:10p, and it was time to turn around. On the return leg the lift was in about, but not exactly, the same spot, supporting the light wind random trigger source theory.

Overall the experience was fantastic.  Kempton and I had lots of great discussions regarding in-flight decisions and he was willing to try out my theories by deviating from the path he would have taken.  We supported each other while the other was flying by calling out cu’s in the distance, timing cu cycle time, looking up, tracking other gliders, calling altitudes, etc.

I would also really like to thank Rex and Noelle Mayes, and the rest of the crew at William Soaring for some of the best hospitality in Soaring.  The atmosphere is amplified by a top notch group of local pilots and amazing accommodations.

August 26, 2012

Libelle 201B - Return to Flight

During the annual inspection of my Standard Libelle 201B S/N 181, a crack was discovered in the main spar spigot.  This happened in March of this year.  The following 5 months were filled with repairs and communication challenges with Germany.  However the outcome was positive and the Libelle is now repaired, determined airworthy, and has been returned to flight.  The following post is intended to benefit other Libelle owners so that they may inspect the area of concern in more detail during their next annual inspection.

The area of concern is on the left wing main spar spigot : See Figure 1.

Figure 1
A detailed drawing, shown in Figure 2, of the welded steel assembly of concern was provided by Glasfaser-Flugzeug-Service

Figure 2
The crack was found in the weld surrounding the main pin, shown in Figure 3.  The crack was difficult to see in the picture so I outlined its general shape in red.  It is important to note that the main pin is not welded to the rest of the assembly, the weld attaches a thin walled tube that accepts the main pin to the rest of the assembly.  The main pin is machined separately and is not heat treated nor hardened.

Figure 3
Figure 4 shows the area with paint removed and a stir stick inserted between the rapping plies and steel assembly.  This is the area of concern regarding corrosion due to trapped moisture.

Figure 4
Figure 5a shows the assembly after the plies that rap the assembly have been removed.  Figure 5b shows the removal of the pins that attach the assembly to the upper and lower spar caps.  The best way to remove these pins is to use a pin of slight smaller diameter, a large C-clamp, and a large diameter deep socket.  Use the pin and C-clamp to press the pin out with the socket as a backing plate that allows the pin to slide thru.

Figure 5a and 5b
Once the steel assembly has been removed the thickened resin used to bond the assembly in place was removed, shown in Figure 6.  The important aspect of the step is to remove the non-load bearing thickened resin only, no fibrous spar cap material can be removed, or the structural integrity of the spar will be compromised.
Figure 6
At this stage I decided not to have a certified aircraft welder try to re-weld the steel assembly so I ordered a new assembly from Glasfaser-Flugzeug-Service.  When it arrived I discovered that it was made from much thicker steel and fit slightly differently than the original.  I was not concerned about alignment because the pins and width of the spar caps filly constrained the new part in the same position as the old part.  I later found out that the new assembly is slightly different than the original because it is the assembly used on the Kestrel and the one part has been approved as the replacement for both the Kestrel and Libelle.  Figure 7 shows the new part bonded in place.  Note the squeeze out of the MGS 285/cotton flox mix.  It is important to get lots of squeeze out during the bonding process to ensure there are no voids.  Also note that the joint is design so that all loads go thru the pins, the bond between the assembly and the spar caps and shear webs is just additional margin; same is true for the rapping plies.  Figure 7 also shows the pins installed, I chose to fill the thru holes in the pins with steel filled resin to prevent moisture collection in the future.
Figure 7
The final operation is to cover the area in fiber glass, and post cure the area to 130deg F.  Figure 8 shows the spar rapping plies before the resin has cured.  The tech note covers the detailed ply layout and position.  The post cure was achieved by creating a tent around the spar end and using a space heater and digital thermometer from Home Depot.

Figure 8
 The entire process was oversaw by an experience composite repair technician, a certified aircraft inspector, and myself.  When we agreed all work was done in accordance with TN201-31, the IA filled out a 337 and submitted it to the FAA and signed the aircraft logs to return the glider to airworthy condition.  For the first flight after the repair I planned a short flight to expand the g envelope in a safe environment.  For the flight I replaced my compass with a g-meter and planned a +2.0g wind-up turn followed by a -.5g pushover.  I used a go-pro camera to record the data.  A screenshot of the g-meter is shown in Figure 9.  I have since open the g envelope to +3/-.5g.
Figure 9
My first cross country flight in the Libelle was a 650km out and return flight along the infamous Owens Valley.  The flight trace can be found here.  The Libelle is truly and amazing glider and I'm very happy to be flying it again, however it is true that I purchased a Schempp Hirth Discus A during the 5 months my Libelle was down for repairs.  I plan on tuning the Discus to the same caliber as the Libelle, but the Libelle will always be my favorite.

Until the next repair, fly while you can, whatever you can.
Keep Soaring,
Michael BK and 2Y

February 6, 2012

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)

November 29, 2011

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

October 2, 2011

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!)