Archive for August, 2009

Summer Lows

One of the problems that I have with learning (as opposed to just memorizing) weather is that it can sometimes be difficult to pick out the principles when looking at the real-world complexity of it all. Take today for example. On the SFC Prog Chart, I see a pretty strong region of lows over the Great Lakes, one off the East Coast, and a couple of weaker systems over the Midwest and West Coast. What’s the first thing we learn about lows? That they draw surrounding air into them, and that the inflow is deflected to the right because of Coriolis effect, causing counter-clockwise circulation around the system. Now take a look at the Visible Satellite loop. The system over the Great Lakes is a decent illustration of what happens around an area of low pressure. But from the perspective of a student just learning, how strong an impression would that low off of the East Coast make?

8-29 SFC Analysis

2 Animation Vis_Satellite_GLAnimation Vis_Satellite_NJ

That’s where I got to thinking about how I’d teach this. Why not pick out an extreme example rather than trying to pick out something lame from the day-to-day weather? Take the weather picture from 4 years ago today–right about the time Hurricane Katrina was making landfall near New Orleans. A hurricane (aka, cyclone) is basically just a low pressure system taken to an extreme. They dominate the weather around them, and it’s easy to see what all a low does by looking at a hurricane. The pressure at the center of a hurricane (usually in the 800-1000 mB range) is well below any of the examples on today’s weather map. The first thing you’ll notice from the Visible Satellite image is the circulation around Katrina: air moves in along the isobars and breaks to the right to create the counter-clockwise swirl. This wind flow pattern is driven by warm, humid air rising from the surface at the center of the low.

From what I hear, stuck-wing drivers like departing out of a low since the rising air improves their climb performance…whether this is relevant for those of us who never climb above 1500 AGL, I couldn’t say. This rising air around a low also drives cloud formation as the moist air is pulled aloft and cools. Once again, Katrina illustrates this to the extreme: the spiraling bands moving toward the eye are lines of cumulus and cumulonimbus clouds. This is where the rule of thumb that bad weather is usually associated with low pressure systems comes from. (Although I’d call bullshit that the opposite is true–that highs mean good weather. I’ll post more on that this winter when there’s a high sitting over the Columbia River Basin, locking us into low IFR and icing conditions.)

So what happens to all the air that is pulled into the low? The rising air erupts out of the top of the low and spreads out from there. Apparently, with a hurricane, how the rising air is drawn away is an important factor in how powerful the storm will be–if the rising air isn’t being drawn off, it acts as a cap on the column of air at the center of the low, weakening the storm. In the upper atmosphere above the low, there is actually a reversal in the circulation. If you look on the northwest corner of the Katrina image, you can actually see this: there are high clouds that are spiralling clockwise. These are cirrus clouds that are formed from from moist air lofted into the upper atmosphere.

Hurricane schematic

Any other thoughts or learning points for teaching about low pressure systems? Add them to the comments–I’ll be setting this up as my first community ground lesson soon.

Third World Helicopters

Remember the Nigerian Helicopter built from old car parts? I recently saw 2 new entries to aviation industry from the developing world. The first is from a Chinese farmer who built his helicopter from wood, a steel frame, and a motorcycle engine. Apparently, the homemade aviation industry is ripping along in China. The Zimbabwian machine looks pretty ambitious. What really struck me about this one was the dual tail rotor assembly. Both of them claim to be flyable, and both make the Mini-500 that I saw a couple of weekends back (with 20-lbs of dumbbells for ballast, sitting on the floor in front of the pedals) look almost airworthy.

ChineseZimbabwe

I’m not making fun of either of these attempts. I think it speaks to the universal thrill humans get at the idea of leaving the ground behind and seeing the world from above. Would be interesting to see if either of these home-made helicopters are really capable of flight, and whether the designers were able to overcome the many engineering challenges associated with rotary-wing aircraft. The low power-to-weight ratio of piston-driven engines was one of the challenges that kept early helicopters from even getting off the ground, where they would be subject to the aerodynamic challenges of spinning airfoils. Seeing as though these attempts all start with heavy components–like the junked car the Nigerian “inventor” used, or steel and wood blades and structures, it’s hard to believe these could really be getting too high up. Nevertheless, this last one, also from China, not only gets off the ground. If you believe the comments, he’s had it up above ETL. Unlike the first Chinese example, this farmer had help from detailed plans he obtained online.

Graphical R44 Weight and Balance Calculator Tutorial

The R44 Graphical Weight and Balance Calculator Tutorial is uploaded to YouTube now. Watching that is the quickest way to get up to speed on the features and limitations of the calculator. Watch it right here, and then download the calculator here.

Part 61 Changes

Wouldn’t you know it, I just found out about several changes to the FARs that might affect the endorsements, and will definitely affect the requirements for the PPLH and CPLH certificates. That’s supposed to be part of the power of a wiki though–that user communities keep the content evergreen. The rules go into effect late in October, and are summarized here [FAR Changes] and in an AOPA article. The duration of student pilot certificate pilot certificates is now the same as a 3rd-class medical. There’s also a change in the definition of cross-country time, although it’s hard to tell from the AOPA write-up how it applies to helicopters. Looks like I’ll have to dig into the regs some to figure that out.

One thing that didn’t change was the requirement for maintaining instrument currency. The FAA had proposed adding a cross-country flight and specific procedures and approaches.

Dream Analysis

Last night I drove up to Lewiston to do a night dual crosscountry with a friend who owns (and restored) his 269b. Earlier that afternoon I’d looked at the weather to the north and thought we’d have a 50-50 chance of making the flight. Isolated T-storms in the area, ceilings coming down some during the evening, and the satellites showed cumulus clouds and a big fat band of moisture being sucked into the region from the north. Not to mention that anything less than ideal conditions would make me jumpy: from the perspective of flying in the dark, the area around Lewiston looks like a black hole, with the only reliable ground illumination coming from a small, 2-lane road that heads north. On top of that, logbook says it’s been 6 months since I had any night time, but realistically it’s been more like 10. We came up with a flight plan over pizza (KLWS → S73 (Rosalia) → KPUW (Pullman) → KLWS), discussed altitudes and weather minimums. Before heading to the airport, the weather looked good. Calming winds, precipitation localized to our east. KGEG TAF forecast isolated light rain showers in the area, but was otherwise uninteresting. Flight Service said the radar throughout the route was clear and the weather looked great for the flight. (It is was a little disconcerting to have to tell the briefer what airports to look at in the region though.) We picked up and headed north with good visibility and CIG about 7000.

I thought the flight was fine. It wasn’t as dark as I had expected. Still dark enough that, if we’d had to make an emergency landing, we’d wouldn’t have had much of an idea what we were going to be coming in on at the end. Scattered ranches and houses provided visual references all around us, and the times that I took the controls I felt like I had no more difficulty maintaining a cruise attitude than I did during the day. Navigating via Hwy 95/195 and the distant cities was pretty straightforward. There are always more small, lighted, and uncharted towers than the sectional shows–I like to use towers for night navigation, but I’d forgotten about that caveat. I think over cities the small ones get lost in the background clutter, but in the desert you can see every single one.

We put a little too much faith in the Standard Briefing, and I think were a little taken aback by the showers that started popping up in the Pullman area and further north.  I thought some looked sufficiently intense that I wouldn’t have attempted to penetrate them. Partly this is out of inexperience (my typical training flight, day and especially night, was CAVU++), but the blackboard that the towns in this area are dotted on made it hard to figure out if we couldn’t see through the showers or whether there was nothing to see behind them. Either way, the showers cooperated and held off to our east. We had light rain on the windscreen for most of the flight north of KPUW. That, BTW, is a pretty interesting airport–the beacon sits on higher ground to the north; as it sweeps around, you see that the runway is in a horseshoe formed by hills to the north, east, and south. When working the pattern there, I found myself more comfortable climbing until the terrain faded below the landing light, around 700 AGL.

We made it back pretty early, and I was in bed shortly after 00 PDT. As always, discussing flight training and helicopters with K.S. was enlightening and disheartening at the same time, and my dreams reflected what was on my mind at the time. These were the long, drawn-out dreams that come in the early morning when you’re half asleep. I won’t bore you with all of it. The set up was a stop-over in some po-dunk town while on a  cross-country drive with my parents, high school ex-girlfriend, and FAR/AIM. I know it was small town USA because the only place to eat was a McDonalds. I haven’t set foot in a McDonalds in probably 20 years–everything except the McRib I find pretty revolting. So I was pretty disgusted by the whole idea of having to eat there. I decided to make up for it by doing some studying, brought along the FAR/AIM and my usual barrage of books and set up shop at one of the booths. During the meal I got distracted by a spectacular Perseid showing and left my beloved FAR/AIM at the table, somehow expecting the McDonald’s clientelle to show it due respect. After psychoanalytically interesting (but otherwise irrelevant) encounters with the parental units, scowling ex-girl friend, and a runaway horse leading to a 9-1-1 call, I returned to find my booth overtaken by an overeating family. The McDonalds was greasy and getting ready to close. My FAR/AIM was nowhere to be seen.

The unsympathetic response from the staff wasn’t surprising. Why did I care about some stupid book? Probably didn’t help that I described it to them as “big, boring, and completely unappealing to just about anybody.” But my notes! My careful highlighting! God, it doesn’t matter that in a couple of months I’ll have to start anew, what mattered is all that I’d put in to this edition. I searched under every greasy table, behind the counters, and begged to dig through their trash. Finally they gave me access to their lost and found. And this was the surprising part of the dreamscape. McDonald had a library of abandoned books, to the extent that they’d taken to cataloging them between the vats of vegetable oil and hamburger buns. And, there was a whole section dedicated to…FAR/AIMs. Apparently this was one of the most discarded books at this neon red and yellow apparition. None of them were mine. I moped back to my room, and found my dog-eared FAR/AIM tossed carelessly on the floor. I picked it up, flipped through the florescent-highlighted pages, and read a few regulations. I was happy again. Complete.

Obfuscation aside, this dream was obviously about how heavily I still depend on that one book. Does it have to be installed, operational, in operation? For this certificate, when can I log night time? What’s the definition of night time for carrying passengers? For operation of aircraft lighting? Can I…? Like an examiner once told me, “You almost know the regulation. Where’s your FAR?” It’s the one book that’s pretty much always with me, there to clarify that last detail. Even though it’s not the friendliest read, without it I always feel a bit lost. That, and I’m irritated that I was out late and didn’t see a single damned Perseid.

This comes from the experience of being a 200-hr CFI in today’s market. I don’t think being a well-rounded pilot means anything in terms of you marketability. At 200-300 hours, I’m just another inexperienced nobody that needs to “pay my dues” if I want to make it. My flight school will probably hire me eventually, whether I can spell instructor or not, because that’s their schtick. Other schools wouldn’t look at me for more than 0.2539 seconds because they have their own CFIs lined up outside their door struggling to find work. Right now, no owner/chief pilot is going to get past the fact that I didn’t train with his school to see whatever experience and education is on my resume.

From a training standpoint, everything I know about SRT puts it at the top of the pile of flight schools. What would be out of the box for any school would be a way to get graduates from 200 hours to a job. I’d like to see the goal of a more well rounded and employed pilot achieved, possibly through paid internships, instruction from within (eg, a CFII could do recurrent training for VFR operations; would that not fulfill a need in the industry?), mentorships, or some other time building mechanism that gets the 200-hour pilot to the point that they can be insured and hired. Great training and experience doesn’t help much if you’re a lawn-mowing, burger-flipping CFI.

Quick Weight and Balance Calculator Beta Release

Don’t want to read about it? Download the calculator now!

Note: These instructions refer to an older version of this calculator. You can still download it from the above link, and view version 3′s features on the Weight and Balance Calculator B3 release page.

Do you run a weight and balance before every flight? Or do you just guesstimate how much fuel you can carry and assume you’ll be close enough to being in CG? I know guys who don’t do a W&B except for check rides. Not good enough for me. Limitations are limitations, and early in my training I developed worksheets for each helicopter so that I had the baseline CG values for every flight. From there it was easy to add a weather check, and HIGE/HOGE calculations into my pre-flight routine.

Now, there are plenty of these already out there. Maybe your flight school has one. I put some real thought into this though to make it user-friendly and packed with features. First, on the Conditions page, you fill in the red boxes with the basic empty weight and arm data. Password protect the worksheet and nobody can inadvertently alter those values. Next, enter all the variable data into the green boxes: pilot and passenger weight, baggage weight, optional equipment (default is installed), and fuel. After the passengers and baggage weights are entered, the Calculator displays the maximum allowable fuel weight (which may be greater than the fuel capacity). The CG graph is updated automatically with the take-off (solid green) and zero-fuel (open white) conditions. Endurance is based on a an editable burn rate (usually 8-10 gph). This is a quick and clean way for students to see how CoG shifts and changes during flight. By unlocking the red cells, they can develop a better understanding of how weight and arm are related to payload capacity.

Quick Weight and Balance Beta Screen shot

I thought about hiding the calculations page altogether, but as a learning tool it’s great. Your students can complete calculations by hand and then check their calculations there. For a beta version, this is also a good troubleshooting tool.

The student worksheet is meant to be used day-to-day for manual calculations. The graphs, arms, weights, capacities, and limitations are reproduced from my POH, but you must confirm that they are consistent with your aircraft’s POH. All cells are unlocked and the sheet is unprotected so you can enter the data for your aircraft. The rest of it is simply an intuitive template for doing W&B calculations and gathering pre-flight data. It should also print out very nicely.

A few disclaimers. I have tried it with several helicopters and it works fine. They are all Beta IIs though. I also run Windows Vista and Microsoft Office 2007, so I have no idea how the Calculator will work with your system. I do know–and this one’s important kiddies–that you must enable active content and macros. The ultra-histrionic Office 2007 automatically disables these features unless you tell it to enable them. I also locked the worksheet so that you’d have to read the instructions. Getting the unlock is easy, but it does require an active internet connection.

I’d like to see some ideas for practice problems that force students to develop a working knowledge of CG. The calculations themselves are only tedious, but applying them to real-world scenarios is what I’d like to get at. In the screen shot, for example, I have to take 240-lb Bubba on a 1.25-hour flight. Can I do it without him having to leave his boots behind?

Anyway, you can download the Quick Weight and Balance Calculator Beta right here or from the Extras! page. This post, however, is where comments, criticsims, corrections, and suggestions belong.

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Comments

I want people to be able to come here and comment freely. But, in the beginning anyway, I’m requiring that all comments be approved before posting. If your comment doesn’t show up right away, patience. I’ll get to it.

Wiki Rotorcraft Flight Manual: Ground Zero

I’m sitting around, trying to figure out how I’m going to get from 246 hours of helicopter time to 1000 hours. Networking has never been my strong suite, and I don’t have anybody who’s willing to mentor me through this phase. That means I need to be a flight instructor. For me, personally, this is no problem. Flying is a second career for me, I’ve taught before, and I think it’s great fun and rewarding. Right now though there are 13.2 million CFIs out there, some of who just finished their CFI yesterday. I need a way to stay sharp, and if I’m not working or working on a rating, I just can’t keep up.

I thought I would expand on my otherwise basic lesson plans, and in doing so I came up with an idea. Since I’m on VerticalReference every day, and there are many knowledgeable pilots there, why not draw them in? So I put this post up: Teaching Techniques: Hovering. I thought this could evolve into a great series–the “Teaching Techniques” tag could be a search term that anybody could go back and look at in the future. I thought there’d be enough idle CFIs that it’d get a lot of comments. I even committed to updating the first post based on the comments.

By the time the topic was dead, it got a disappointing 14 comments (3 of them were mine). Hopefully that isn’t foreshadowing…. But it has over 1800 views, which is 2-6 times the views that other posts in the Flight Training forum get. I thought the outcome was pretty useful, although it took me processing people’s experiences and drawing a lot from conversations I had. In the end, I didn’t think it was successful enough to warrant a follow-up.

Well, I came back to the idea after looking into a WordPress blog for another project. Since that project didn’t pan out, I now have time to work on this one. Anyway, check out About Wiki RFM if you want to know why I think this is a good idea and how it works. If you agree that it’s worth it, contribute once I start adding content! Otherwise I’ll just let it join the rest of the electronic jetsam that’s drifting out there. If it takes off, even a little bit, I’ll figure more out about how it should work.

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