Tuesday, September 26, 2006

JEP FI-3: Attitude indicator, Stalls, Slow flight

(Update: attitude indicator's fpm (details below), and I'm told that C130s could use lil' old JGG.)

Goals:
  • Slow flight maneuvering.
  • Power-on stalls (intro).
  • Power-off stalls (intro).
  • Maintain climb/descent by instruments.
  • Turn around a point.

Flight: Preflight and pre-flight briefing, normal. Taxi for take-off on 13 (light changing winds; by the time we got back they favored 31). Take-off, mediocre. I think on that one Chuck took over because I had too hard of a turn for the airspeed, which I had probably allowed to slip below Vx. Up-river to the practice area and begin...

We trimmed up for cruising airspeed and began to learn more instruments. The attitude indicator (artificial horizon) has a variety of uses. In a very general sense, which is all the attention I had really paid it before, it tells whether you're pitched up or down and whether you're rolling left or right. It also, though, tells specifics on those two axes as well. There are horizontal notches above the horizon for a +500fpm climb, and a line below the horizon for -500fpm descent. Putting the little "virtual plane" on those lines, you can verify the rates using the VSI (vertical speed indicator). (Update: Those lines correspond to those rates at cruise speed, which is what we were doing when we looked at them.) Additional lines are below the -500fpm markings, but we didn't explore those. There are also, below the horizon, diagonal marks with which the wings of the virtual plane align for a standard rate turn; again, there are other diagonal marks but we didn't go further. Across the top of the indicator are tick marks as well for different bank measures, but I didn't process them while looking at the lower marks.

We then practiced slow flight, reducing airspeed further and further until the stall warning came on. Then we maintained and used the right rudder to turn right and simply had to let off the right rudder to turn left. The P-factor adds a left-turn tendency, so just by not resisting it you can turn left.

Then we did power-off stalls, where Chuck demonstrated one and I did one or two. They were uneventful, requiring a check of the VSI to in fact verify that the stall had been achieved. Slow flight, pull back, stall, pitch forward, regain control, throttle up, nose to the horizon, establish positive climb rate, recover.

Next was power-on stalls, where Chuck demonstrated one and I did one or two. These were slightly more eventful, and in fact, despite Chuck preparing me for it, I still instinctively grabbed my seat when we swung to the left and had a windshield full of ground (not that bad, again, I'm over-dramatic). Then I did it. Reduce airspeed (just to minimize how much has to bleed off to stall), full throttle, let it pitch up, then help it when it doesn't want to go any further, keep helping, keep helping, then mush. And with as much right-rudder as I could possibly put in we still swung left, but it broke (the stall), swung left, I pitched forward, already at full throttle, control came back quickly, nose to the horizon, establish positive climb rate, recover.

We moved on to descending S-turns to do some descending turns while clearing an area of interest over a clearing in the woods with a few buildings. Now was the time for turning around a point, but this was to be a descending turn. I'm comfortable with turning, and was comfortable using the rudder and turning a little tighter if I felt I was getting too far off the ground reference. I didn't pay quite as much attention to the descent as I should have and so we at least stopped descending if not even gained a little altitude for a little bit. We rolled out of that towards the James and headed back to JGG.

We entered the pattern on 45 downwind for 31 and I did all the pattern work and radio calls. We went through the pattern 5 times. I had a tendency to not be quite parallel with the runway on downwind, leading to a a short base, until the last 2-3 patterns when I consciously kept farther away (once too far -- couldn't see the numbers on the runway because of trees!).

I think each one got better, and each one was a little different. On one of them, we looked up after using the heading indicator to decide when we were fully turned onto base to see a C130 out in front crossing our path! Luckily we were about to turn final and he was plenty far beyond the airport (spraying for mosquitos; some residents called JGG to complain about the huge low-flying military plane, like that thing could possibly use JGG!). I don't have a good sight picture for final yet, but the procedure for getting through the pattern to final has sunk in, I think, so the next lesson I should be able to absorb more and maybe start doing the flare myself (Chuck did them all, with me "helping" as an observer, until the last one where I really just felt that I was pulling back as hard as I could, brute force not brute smarts!).

The 4 take-offs were each different, too. At least one of the early ones had a notable problem with tracking the center line, so I consciously worked on that and it generally improved. On the next to the last one I misjudged when the nose strut extended and that resulted in an (off the ground) excursion over the grass to the left of the runway, so I was more attentive to that on the next take-off. I was definitely paying attention to Vx and trying to keep it, but I completely brain-fudged it on one (the last one, maybe?) and saw that we dipped below Vx and my solution was to increase pitch (should have been to decrease pitch) and so of course the stall warning started squealing and Chuck stepped in, but then turned it back to me as we turned off and climbed back to 850' at ~80-85 MPH to re-enter the pattern.

Discussion:
  1. Why practice stalls? Power-on stalls simulate what was about to happen on that last take-off. If we had stalled at 300' full throttle, well, ouch. That would have been pretty nasty. Power-on stall means full throttle stall. We practice them so that if we do stall on take-off we can recover as quickly as possible while losing as little altitude as possible. At 300' over trees, houses and a school, there ain't much altitude to lose safely. Power-off stalls are the opposite; stalling on a landing approach. This one's not quite so bad, since you don't pitch down and dive, but it's also almost worse because it's not obvious that you're dropping (in 388, at least). Either way, it still has the potential for major nastiness and still needs to have lightning-fast responses to recover quickly and while maintaining altitude.
  2. More notes on Vx: Vx is the best angle of climb (gets you aloft the fastest), the best glide angle (keeps you aloft the longest), and corresponds to the maximum coefficient of lift; it gets you up the best.


Self-Assessment: Overall, more confidence than last time and it felt good today, not so stressful. I got into the groove with landings, and learned from each take-off, but still need to put all the factors together.
  • Preflight: Good.
  • Taxiing: Improved even since yesterday, more needed especially in tight spots.
  • Take-off: Better indeed. Maintaining the centerline while still on the ground under full power needs practice and sticking Vx throughout the initial ascent (for JGG) needs practice.
  • Maintaining airspeed: Better, more practice.
  • Stalls: Was ok, but didn't have to try to recover within a certain altitude... we'll see next time.
  • Slow flight: Was ok for what we did, didn't do enough to assess.
  • Maintain attitude by instruments: Good. We'll see when harder scenarios are introduced.
  • Pattern: Much better today (thank you 5 landings!). More practice for adding throttle when descent rate is too high and not making too wide of a pattern (downwind).
  • Landing: Still assisted by Chuck; my assessment of the situation and ideas on correction need active work.
  • Radio calls: Decent, will improve with practice.


Next: Unknown - Chuck is unavailable until Tuesday afternoon, and 388 goes for glideslope maintenance on Tuesday.
  • More of the above!
  • Will have to check the syllabus...

Hours logged this lesson: 1.7
Hours logged total: 4.2
Take-offs and landings this flight: 5
Take-offs and landings total: 7

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