Another wave flight

Moshe writes about April 23:

Wild spring day. Thermals were higher than expected, so I headed out cross-country to the northeast, across the wind. But I found rather poor thermals from near Moosilauke to the Franconia area.  I chose not to go to the mountains which were even farther downwind.

Instead I headed upwind (northwest) to try to get within range of Dean - and stumbled into wave!

I climbed to 13000 feet, but with a 50-knot wind across my course line, the 32 miles glide back home was still a challenge - and the arrival altitude promised by the glide computer was completely meaningless.

I tried to make way crabbing sideways within the up-wave.  But that was very slow, and it also wasn't leading in quite the right direction.  So I plunged upwind through wave sink to the next wave cycle.  In my low-performance glider that cost a lot of altitude!

Back in the Post Mills area, it was very turbulent below 3000 feet, so the landing was "interesting" too. 

Visibility was great, The Whites were "right there," and I could see Lake Champlain through the Waterbury gap in the Greens.

In retrospect, I think the Franconia area was in down-wave, thus the bad thermals. Had I gone downwind closer to the mountains then maybe I could have found up-wave - or not, as the wind would interact with the mountains.  The few clouds I saw in the area with bad thermals looked curly, so they must have been roll clouds. The thermal that threw me into the wave increased to 10 knots up high near the upwind edge. The wave lift was about 4 knots, weaker at 13000 feet, but I was reluctant to go higher without oxygen.

Flight log here.

Traps that can catch you

On some XC soaring days the areas with few clouds look iffy, and areas where there are plenty of obvious cumulus clouds look inviting.  That can be a trap, though, since the numerous clouds can fill in and become an overdeveloped layer with little lift.  It takes an hour or so for the layer to evaporate, then the sun reaches the ground again, and new thermals develop.  Or not.

Another trap that we are susceptible to when soaring XC is the concept of a landable spot that we keep within range.  Of course that's necessary, but not always sufficient.  If you get low and have to stay close to the one landable spot in the area, you can't reach lift that is just a bit too far away.  Moreover, not all the "landable" spots are desirable.  Some are hazardous, albeit better than nothing.

Both of these traps caught me Saturday as I ventured out XC, despite cloudbase being lower than forecast, not much above 5000 MSL - conditions that normally make me stay close to the home airport.  After traveling North to outside glide range of home, I met Greg and Dan who seemed to be heading SE.  I headed NW to near the Montpelier airport before realizing that that area was overdeveloping.  Turned back East too late, and as I got lower had to abandon the better looking clouds and head to the supposed safe spot, Carrier airstrip, South of the Barre stone quarries.

I've never seen that airstrip before, and as I got close to it got a little scare, since it's hard to spot.  There was a large flat farm field a bit further North, but I didn't know how tall was the crop that looked like corn.  The GPS got me to right over the airstrip though, at about 1000 feet above the runway which is fairly high at 1600 MSL.

Next problem was that this runway is about 50 feet narrow, with various hazards along the sides: rising banks, drop offs, fences, cows, trees, buildings, and vehicles.  It's also sloped: rising to the North.  As they say, if the slope is obvious from the air then it's significant, and one should land uphill.  With light wind, that was fine.  The Northernmost third of the runway is a bit wider and flatter, and does not have hazards along the edges, so that's the preferred landing zone.

Never give up though!  I found a small bump, and worked it carefully.  After some time, gained 100 feet, then more.  Eventually got to 4000 MSL (still only 2400 AGL) so explored a bit further, and lost the altitude.  Rinse and repeat.  That went on for more than an hour, with my mental state alternating between hope and resignation.  Never got high enough to reach a better landing spot.  Kept losing sight of the airstrip, so used VOR navigation to find it again and again.  No, I didn't use the VOR signal, it's just that the (MPV) VOR building is easy to spot visually, and then looking a couple of miles Northward from there helped me re-spot the airstrip.

Finally the clouds broke up and the ground started heating up again.  Alas I didn't have the few extra minutes it took for the thermals to restart.  But the skies to the NE looked good soon after I landed, of course.  Landing was OK, having short wings helps.  (And they also make landing out more likely.)

Mr. Carrier was there and friendly.  He knows Karl well - Karl flies there often from his home field a few miles West of there.  Mr. Carrier also has been to Post Mills, he flies an ultralight out of his field.  He's working on widening the runway a bit: bulldozing the embankment on the East edge and moving that material to the dropoff a bit further South on the same East edge.

Driving directions to Carrier's, in case you need it: North on 110 9 miles from Chelsea to "downtown" Washington, turn left by the store, about a mile to the farm (keep right at the forks).  Big house and barn.  The airstrip is not visible from the road.

Thanks Paul for the retrieve!

- Moshe

Instructors

Our club is very lucky to be made up of so many dedicated volunteers, and the secret to our success is the willingness of everyone to help everyone else get in the air.

Yesterday and today, this volunteerism was exemplified in spades by two of our members, who successfully made the transition from "Expert Pilot" to "Rookie Flight Instructor."

Congratulations to CFI Evan Ludeman and CFI Moshe Braner!

Becoming a Certificated Flight Instructor isn't easy or cheap. Knowledge, experience, and skill are only the beginning.  You have to have a Commercial Certificate and then pass two more written tests and a flight test administered by an FAA Flight Inspector.

Moshe and Evan spent a week at CFI Camp in September and completed their Commercial Certificates at the end of that month. Then they sat around and waited for a month for the FAA to find a qualified Inspector, eventually choosing the obvious guy, the only one within 1000 miles of here.

The two flight tests went very well, unsurprisingly, and Evan and Moshe can now transfer their expertise to you, complete with a signature in your logbook.

CFIs are not all alike, and we are fortunate to have these two in our club.

Evan and Moshe will make us all better pilots, and they will do way better than whoever soloed this guy:

Weekend report July 11 - 13

It was a 3 day weekend for PMSC.  On Friday Moshe (RU) had a nice 206 km (304 OLC points) flight to Franconia, Peacham, Knox Mt. and Hanover.  Andy Lumley. took the towplane up to Franconia and brought back FSA’s SGS 2-33 and Blanik L-23.  They will be based at Post Mills until they get their towplane fixed.

Saturday was a marginal local soaring day but between FSA and PMSC operations there were 14 flights.

Sunday was a marginal training day.  Bill braved the weather to fly over from Portland to fly a couple of patterns with Henry.

Andy towed all three days.  Thanks Andy!

While FSA is with us we will be logging all their flights on our sheets too.  For glider IDs we will us the following:

For the 2-33s – “67” us.  “68” them.
For the Blaniks – “BA” us.  “BB” them.
Private glider – “US” is them.

(their 2-33 is N33968, their Blanik is N118BB and Jim David’s ASW-20 has competition ID “US”)

Moshe sent along some pictures from the weekend.

- Tim

BLIPspot renewed

The BLIPspot forecasts for Montpelier, VT have been renewed for 2010 (by me - anybody want to help me pay for it?). They can be accessed via this link, which has been added to the list of Weather Links on the right.

If you are not familiar with the BLIPspot, see my long note from last year

- Moshe

Blip

For several years now "Dr. Jack" Glendening, a West-coast meteorologist, has arranged an on-line soaring-specific forecast based on National Weather Service data. Although that data is available elsewhere, putting it all together into a forecast of the day's thermal height and strength (and cloudiness) is a chore better left to a computer program. His setup also generates color-coded maps that neatly show the wider geographical patterns. But for local, or even short-range cross-country flying, you can't beat his one-page textual summary for a specific location, known as "BLIPspot". The closest BLIPspots to us were in Mass. and Ontario, and for years I've wanted one in our area.

So now I've gone ahead and asked Dr. Jack to make one for us, located at the Montpelier airport. Why there? It is not a soaring base per se, but the 3 soaring operations in Northern Vermont are within 20 miles around it. It does not boast elevation as high as nearby hills, but is 500 feet higher than the valleys, and represents the relatively lower ground between the mountains where some thermals are needed in order to soar cross-country in our area. We can then expect lift to be better in the mountains. If we were to base a BLIPspot on Spruce Mountain instead, for example, the forecast may be good for the mountains, but would be overly optimistic for most of the XC area. Also, this airport is a TAF, METAR and ASOS spot, and thus one can compare the actual temperature and dewpoint, reported hourly, with the forecast and adjust one's expectations accordingly.

BLIPspots are freely accessible to anybody, although you need to "register" with Dr. Jack's site. But the sponsor of a BLIPspot needs to pay an annual fee to create and maintain it. If you find the BLIPspot useful, consider helping me with the payment, this year or in the future.

The new BLIPspot can be accessed either via the main BLIPSPOT page, or directly at this link.

The location of the new BLIPSPOT is shown on the regional "grid orientation" map - it can be accessed via an "Identified Locations" map for the NE region.

Important message from Dr. Jack:

PLEASE PASS ALONG THE FOLLOWING INFORMATION TO ANY WHO WILL WANT TO ACCESS THIS BLIPSPOT:

This BLIPSPOT is available for viewing by anyone via the internet, but access to the "current day" forecasts (which everyone will want) does require that each user individually "register" (which is free) at this link. I require individual registration, rather than group registration, because knowing the number of individual users of each forecast product is important to me.

Registration also allows access to the other "free" DrJack forecasts, which includes "Thermal Updraft Velocity" BLIPMAPs, "Buoyancy/Shear Ratio" BLIPMAPs, all "Previous Day" BLIPMAPs, and all BLIPSPOTs. "Subscription" (which is not free) is required to gain access to the other DrJack BLIPMAP forecasts. Normally registered/subscribed access occurs through use of a DrJack registration "cookie", for which one's browser must accept cookies from the "drjack.info" domain. (In lieu of accepting cookies, more complex "cookieless" access methods are available.) For further information on DrJack registration, see this link.

Notes from Moshe:

* I use cookieless access by embedding my registered ID in the URL thusly:

http://www.drjack.info/BLIP/RUC/SPOT/FCST/montpelier_vt.txt?id=user&pw=password

* For BLIPMAPs go here.

* More details on the BLIPMAP and BLIPSPOT parameters can be found here - I've written up some interpretive text (shorter than the page linked above, longer than the brief definitions in the bottom of the BLIPspot page itself):

The BLIPspot includes forecasts for several times of day, the important ones for us would be: 15Z (11 am EDT), 18Z (2 pm), and 21Z (5 pm) - spanning the possible soaring hours. Note that the time dimension is only available in BLIPSPOTs, not in the BLIPMAPs.

Temp@2m is the forecast ground temperature (actually 2 meters above ground), on which the predicted thermals are based, and can be compared with actual temperature (as measured or reported in METARs, e.g. at 11am) to judge whether the BLIPspot forecast is working out.

BL throughout stands for "boundary layer", the part of the lower atmosphere mixed by the thermals.

BL Depth shows how high the thermals will reach AGL.

BL Top shows the altitude MSL at the top of the thermals.

Hcrit: the very tops of the thermals are too weak to use, "Hcrit" shows the expected top of the usable part of the thermals [ftMSL] (assuming blue thermals, otherwise cloudbase caps the usable top).

Hgt.Variab. shows the uncertainty or variability of the BL depth, it will be this much higher over hot spots (4 degrees hotter - or effectively so, via higher ground elevation). This variability is influenced by the temperature profile of the atmosphere: if there is a sharp inversion capping the thermals, for example, then this variability will be small. On the other hand, if the lapse rate is still high at the tops, the thermals will be significantly higher over hot spots (or lower, if the ground temperature turns out lower than forecast).

W* is the Thermal Updraft Velocity (in fpm - subtract glider sink rate (typically about 150 fpm) to get climb rate).

B/S = Buoyancy/Shear Ratio. This compares the upward buoyancy of the thermals to the horizontal shear due to the change in wind speed or direction with altitude. Thermals may be unworkable if B/S is 5 or less.

BL Wind = Wind Speed averaged through BL [kt] - keep in mind that wind speed may change quite a bit with altitude - look at the wind profile at the bottom of the BLIPSPOT.

Direction = Wind Direction averaged through BL [degTrue] - keep in mind that wind direction may change quite a bit with altitude - look at the wind profile at the bottom of the BLIPSPOT.

CLOUDpotent predicts the potential for the thermals to condense into cumulus clouds. Expect clouds if this is positive. If this is large then the clouds will be thick. (This number is the height difference between the top of the thermals (if they were blue) and the expected cloudbase (due to moisture).

sfcLCL = Base of Lowest Clouds, if CLOUDpotent>0 (LCL = Lifting Condensation Level based upon sfc. humidity) [ftMSL]. If that's higher than Hcrit then the prediction is that cloudbase will be unreachable.

ODpotential is the potential for "overdevelopment" - expect extensive clouds if positive. (This number is the difference between H(TI=0) & blCL) [ft].

bLCL = Base of Extensive Clouds, if ODpotential>0 (bl CL = Condensation Level based upon BL humidity) [ftMSL] - the difference between this and sfcLCL is that this is based on the moisture of the humidity of the whole BL, while sfcLCL is based on the humidity near the surface - if the air aloft is fairly dry, then there will not be "overdevelopment" and the condensation of the moisture brought up from near the surface will result in only limited cu.

CAPE = Convective Available Potential Energy [J/kg] - if this is high then the condensation in clouds will release a lot of additional "latent" heat and the cu will get thick and there may be thunderstorms.

DewPt@2m = Dew Point Temp. at 2m AGL [F] - this is the basis for the forecast of cloudbase (sfcLCL), and can be compared with actual dewpoint (as reported in METARs) to judge whether the BLIPspot forecast is working out.

As you can see, there is a lot of good info at-a-glance in the BLIPspot: not just how strong the thermals will be, but also their workable height, change during the day, and the potential for overdevelopment.

Additionally, the BLIPspot lists the predicted wind profile (speed and direction) at different altitudes at several times. The asterisks in this table bracket the BL top altitude.

One thing the BLIPspot does NOT offer is a sense of how things will be different in different places. If planning a long XC, one should also look at the BLIPmaps, which roughly describe many of the same parameters via color coding on a map. BLIPmaps for thermal strength and B/S ratio are available free (as are BLIPspots, once sponsored), while the other BLIPmaps are available by paid subscription.

- Moshe