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#11
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Turn to Final - Keeping Ball Centered
On Mar 12, 2:18 am, "Ken S. Tucker" wrote:
-- IGNORE BELOW -- Depends on the A/C, what were you flying? In an F-4 doing a 3-4g bank is easy, but in a trainer I'd suggest 2g max. Ken -- IGNORE ABOVE --- Assuming you're not flying an F-4 in a sim, we'll move on to reality.... This fear is (correctly) pounded into every aspiring/training pilot -- don't cross control stall on turn to final! And that's that. So -- pilots being the life loving critters that they are, add "a little more speed" as a "buffer." Because we all know we can't stall at X speed, right? And then we turn onto final 10-15-20 knots faster than required and then wonder why 3,500' strip is just barely big enough. So we'll assume you still need three things: 1) A correct understanding of stall 2) A consistent, safe procedure for the pattern in the airplane you're flying 3) Demonstrations by a CFI of the sensations and perceptions of the event prior to and just at the stall in the various possible circumstances (turn to final being one). For (1) you need to get into your head that stalls -- while often described in terms of speed -- are a function of angle of attack. The wing (or a portion) can't fly anymore because the flow of air below and above isn't working as designed (I'm sure you've seen the pictures of burbling air over the wing). This can be demonstrated on the ground by a CFI with a model airplane. Then he/she should take you out and demonstrate this in an appropriate airplane. For (2), you need to fly patterns at altitude and figure out the optimal Power (1500 RPM?), Attitude (Nose about there, trim to there), and configuration (gear down, flaps full, etc) for your airplane at the speeds you will be flying in the pattern. And then (with your CFI), explore the left side of the envelope (slower). What you will find is that in normal 30 degree banks (which you were taught to use in the pattern), with coordinated turns the airplane continues to fly quite well 30% over stall speed (1.3 Vso). Does this mean you will drop out of the sky if a gusts catches you and momentarily disturbs coordination? No. The airplanes we fly (especially trainers) are very forgiving in this regard. But keep in mind "momentarily." You should catch it and fix it. For (3), he/she should take you to altitude and show you how much cross control you need to apply to get the airplane to stall. This should ease your mind a bit, but also ingrain a sense of "This isn't good" should you place yourself in that predicament later on. Finally (not on the list but its early), you should practice short field landings often. I'll probably catch flak on this, but one of the biggest problems you will see at any airport on a nice day is small airplanes coming in Way Too Fast. You will know this by watching the approach from a spot on the ground -- the patterns are enormous (2 miles or more from the runway) and the airplane touches down 1/3-1/2 way down the runway and rolls a long, long way. I think (IMHO) this is due to the same understanding you have -- "I might stall due to low speed, so a bit more will give me a buffer to keep me from that unwelcome event." Get some more training in stalls and flight at the low end of the speed regime and join the ranks of safe, educated pilots. Dan |
#12
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Turn to Final - Keeping Ball Centered
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#13
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Turn to Final - Keeping Ball Centered
I don't think anyone has suggested this, but there is a nearly
universal cure if you find yourself uncomfortably out of a reasonable approach condition -- simply say to yourself this isn't looking good enough, go around, and do better the next time. It's my uneducated opinion that too many perfectly good airplanes get turned to scrap because pilots continue to commit to an action that has become untenable. You have a hand on the throttle and it's important to remember to be ready to push it in if you don't like the way things are shaping up. Don't let ego get in the way of good judgement. |
#14
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Turn to Final - Keeping Ball Centered
In article
, skym wrote: While making a turn to base and final recently, I was aware that I was going to be wide with my normal turn from downwind through base to final, so I banked more to keep as close to the runway centerline as possible. I kept thinking about the infamous and usually fatal stall/ spin by some pilots in this situation, I kept thinking that if I keep the ball centered, even with a very steep bank, that I would be ok and not auger in. Some of you instructors and old pros...is this correct? (Not that I intend to make it a practice.) 1. You can stall with the ball centered -- if the ball is not centered, you can get a spin more easily when you stall. 2. The stall speed goes up as the square root of the secant (1/cosine) of the angle of bank. At: 30 deg: 1.07 45 deg: 1.19 60 deg: 1.41 75 deg: 1.97 -- Remove _'s from email address to talk to me. |
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Turn to Final - Keeping Ball Centered
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Turn to Final - Keeping Ball Centered
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#17
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Turn to Final - Keeping Ball Centered
Dudley Henriques wrote:
Ask your instructor to explain to you what happens to the stall speed in a LEVEL turn as opposed to the stall speed in an unloaded gliding turn from base to final. This is a distinction you should definitely be aware of. If he's maintaining a constant rate of descent during the turn there is no distinction. The load factor decreases only if he is accellerating towards the ground. |
#18
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Turn to Final - Keeping Ball Centered
skym wrote:
Thanks for replies. I had meant to address the speed issue since I knew the stall speed increased with bank. I also kept my speed higher than normal in the turn because of that. I left it out of the question, and shouldn't have. Assuming I keep the speed up, is the centered ball a reliable guide? A reliable guide for what? It's an indicator of coordination, which is always a good idea. Your airplane flies more efficiently. |
#19
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Turn to Final - Keeping Ball Centered
Why does no one distinguish between a level turn (constant acceleration into
the center of the arc, which increases load factor) and the load factor in which the same angle of bank exists in a descent? When descending you are moving away from the center of the in the vertical direction which means less acceleration towards the center in the original plane (geometric). You can feel the load factor difference in the seat of your pants when descending, compared to maintaining level flight in a steep bank. I don't understand how people can claim the load factor is the same descending and turning for example in a 600 fpm descent. It is no different than twirling a weight at the end of a string. Takes more energy to maintain the string at a higher horizontal angle. 2. The stall speed goes up as the square root of the secant (1/cosine) of the angle of bank. At: 30 deg: 1.07 45 deg: 1.19 60 deg: 1.41 75 deg: 1.97 |
#20
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Turn to Final - Keeping Ball Centered
writes:
Why does no one distinguish between a level turn (constant acceleration into the center of the arc, which increases load factor) and the load factor in which the same angle of bank exists in a descent? When descending you are moving away from the center of the in the vertical direction which means less acceleration towards the center in the original plane (geometric). The center just becomes a line in that case, doesn't it? You end up with the same centripetal force needed towards that center line in order to turn. You can feel the load factor difference in the seat of your pants when descending, compared to maintaining level flight in a steep bank. I don't understand how people can claim the load factor is the same descending and turning for example in a 600 fpm descent. Nosing over into a descent does temporarily reduce load factor, but as soon as you're established in a constant descent, you're back at the same 1g load. Gravity is *acceleration*, not *velocity*. -- James Carlson, Solaris Networking Sun Microsystems / 35 Network Drive 71.232W Vox +1 781 442 2084 MS UBUR02-212 / Burlington MA 01803-2757 42.496N Fax +1 781 442 1677 |
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