Monday, November 06, 2006

Personal speed record

So I thought I was really moving the day before but on this trip of which would take about 2 hours and 40 minutes in a no wind condition only takes us 2 hours today. From this picture you can see we are climbing at an indicated airspeed of 130 kts which is pretty much as slow as you are going to climb. The reason being is that we are nearing our cruise altitude of 27,000 feet and there is a 133 kt wind pushing from behind. We are still climbing in this shot at 700 feet per minute and on the EHSI screen we are grounding 312 kts ! Again so nice to see but again if we had to return this day it would have taken about 3 hours and 30 minutes !

This little contraption here is God's gift to man. Contrary to popular belief that God's gift to mankind was pilots ;) ;) It has a ton of sensors (air data computers) that know where we are heading, how fast, temperature outside, pressure and compute it all to give me our True Air Speed TAS, or MACH number (jet guys don't laugh). MACH is basically a ratio of your current true air speed in relation to the local speed of sound. So if its -30 outside where I am at and I am doing 200 kts TAS I am going at .34 MACH or 34 percent of the speed of sound (yeah I know it isn't much) A Boeing 767 for example regularly cruise at Mach .84 or 84 percent of the speed of sound. Problems arise when you get close to the speed of sound because of the speed of the air actually flowing over parts of the wing maybe closer to mach .95 while the airplane is moving at mach .80. If the air goes super sonic (above mach 1.0) then you have a shock wave and also laminar flow over the wing is gone and that equals a bad day for the jet driver. We are limited to mach .48 but that's because of our wing design and the design speed of the airplane. Anyways the GPS in this screen is giving us the current winds.... 223 degrees true at 132 kts. Which with our current track equates to a 111 kt tailwind. Now if we turned to a track of 043 degrees true we would have the whole 132 kts on the bum and would be grounding close to 400 kts !

Level at FL270 haulin ass !!! If I was flying a jet right now (except a Cessna Slowtation) grounding 370 kts would mean about an 80 kt headwind !! The best part of this story is that we are overnighting in New Brunswick (Nouvelle Brunswick en Francais). The winds abated as the jet stream (basically the dividing line in the atmosphere where cold air is to the north and warm air to the south) moved south and the cold air pumped in behind it. It only took 2 hours 30 minutes to return to only 30 minutes longer then the way down. As for the Jet Stream it usually sits around 25,000 to 30,000 feet in the winter time and when you look at an upper level weather chart you can see roughly where it is. So if you wanna know if its going to be warm, cold or seasonal you can just look at it on the weather channel and if you lie to the north of it and its way south then its freekin freezing (if in winter) or if it swings way up north then warm is being pumped up.

So what does a Cold Front look like after it has gone by ? Well like this !
We had just taken off as the front had passed and this was about 120 miles northwest of the surface location of the front. Because the advancing cold air isn't a straight up and down wall of air it slopes. You can picture an advancing cold front like a wedge of air moving and pushing warmer air out of the way. In the summer the contrast between the cold dry air and warm moist air pushes the warm moist air aloft causing it to give of latent heat (basically energy given off when dropping down a state IE vapor to liquid or the reverse would take in heat) and keeping the column of air warmers then the surrounding air allowing it to keep rising (positive feedback loop) and with all the moisture its gotta go somewhere so we get rain and nasty thunderstorms. The more the difference between the two air masses and the more unstable the warm air is the bigger the storms get. But in this photo where the cloud is the winds are howling at around 140 kts !!! Fall is great because there is more of a clash between different air mass's so they are more distinct when they go through.

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