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#1
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Tweaking the throttle on approach
Is it normal to constantly fiddle with the throttle on an approach in a small
plane? I find myself frequently making small adjustments on most approaches (unless I'm coming absolutely arrow-straight into the runway and there's no wind). From videos I've seen, this happens in real aircraft, too, depending on conditions. I was under the impression that a steady throttle is ideal, but perhaps that is hard to achieve in a small aircraft. I don't have a problem in large jets--they take forever to answer the throttle, anyway. -- Transpose mxsmanic and gmail to reach me by e-mail. |
#2
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Tweaking the throttle on approach
On Mar 4, 10:50 am, Mxsmanic wrote:
Is it normal to constantly fiddle with the throttle on an approach in a small plane? I find myself frequently making small adjustments on most approaches (unless I'm coming absolutely arrow-straight into the runway and there's no wind). From videos I've seen, this happens in real aircraft, too, depending on conditions. I was under the impression that a steady throttle is ideal, but perhaps that is hard to achieve in a small aircraft. I don't have a problem in large jets--they take forever to answer the throttle, anyway. A typical approach in my Cherokee includes at least a few minor power adjustments after the main power reduction on downwind, abeam the numbers. They are not usually large, probably +/- 100 rpm. I usually attribute this to variable wind (speed and direction) between traffic pattern altitude and ground. Some days, the wind varies considerably on the way down, and larger, or more frequent power changes are needed. On those rare wind-free days (i.e., from the surface up to 1000 AGL), I can set power at 1500 rpm on downwind, apply flaps in my normal places in the pattern, and usually hit the runway nearly where I want without any power adjustments. |
#3
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Tweaking the throttle on approach
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#4
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Tweaking the throttle on approach
On Mar 4, 12:02 pm, Mxsmanic wrote:
The Baron has a CS prop so I can't watch RPM. I guess I could look at manifold pressure. However, I've been going mostly by sound to determine how much power I have applied. I don't know what CS prop guys do, but in my fixed-pitch prop, I always make my initial power reduction based on RPM, I set it to 1500 and then adjust from there, based on the resulting approach. I suspect that with a CS prop, some initial RPM/Manifold Pressure combination is selected. I have found that flying a normal rectangular pattern in the sim is significantly more difficult than in real flight. In the real plane, I compare my actual position to my desired position by frequently glancing at the desired touchdown point on the runway. I find this very difficult to do in the sim, I think because of the difficultly in getting realistic view of the runway from the various legs of the pattern (?). However, once established on final approach, I think the sim is quite good in reproducing the sight picture of the approach. In a light plane, the standard technique is to hold airspeed constant (usually by trimming to that speed), and then fine tune the flight path angle with small power adjustments. But I guess after a while looking out the window gives me enough clues--as well as checking instruments, but often I'll adjust power before I see a change in the instruments. In a normal approach, started from downwind in the traffic pattern, once the initial power reduction is made, I make the rest of the approach mostly without looking at the instruments, except for several checks of airspeed. The descent to the runway is done visually. Also, don't forget that in the real plane your attention will be mostly devoted to looking for and avoiding other aircraft. I've read about being in a stable configuration on approach and that this is a Good Thing, but I'm not sure if that applies across the board for all aircraft and approaches, or just for straight-in approaches, or what. I think it would be quite a feat to be able to fly a pattern and land without hardly ever touching the throttles, except perhaps on the kind of windless day that only occurs in simulators. I can get the aircraft into a stable configuration on approach if the weather is good and I'm coming straight in, but doing it while flying a pattern seems unattainably difficult at times. If you want to be realistic in the sim, then you should try to fly the traffic pattern for most of your visual approaches. (This includes instrument approaches to small airports in visual conditions; break off the approach a few miles out and join the pattern normally.) I agree about the difficulty of setting up a good approach from the pattern in the sim. You need to find a set of zero-wind numbers that works for your sim aircraft, e.g., power setting on downwind, initial power reduction, time until you turn base, position where flaps are applied, airspeed on final, etc. (Timing your turn to base may work better for the sim than the real-life technique of waiting for 45 degrees from touchdown point). You may have to find them by trial and error, but once you have them, they become your starting point for all subsequent approaches; fly by those numbers, and then make adjustments for wind, and other factors of the specific situation. |
#5
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Tweaking the throttle on approach
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#6
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XXX Tweaking the throttle on approach
Mxsmanic wrote: Unfortunately I tend to be impatient in the sim and I'm often still not aligned even as I cross the threshold, unless I planned to land at that airport well ahead of time. I usually come in fast because I'm making rather risky turns on the approach and I don't want to come too close to a stall. The benefit of your simulator is that it doesn't destroy the landing gear on your sloppy landings and that is why it is nothing like real life. It lets you get away with the most terrible landings... (It always says excellent landing to me but that's not what my instructor ever says -and he's right I'd give myself typically 5-8/10). Based on your extolling the virtues of MSX I recently got the latest version and tried it out with the aircraft I'm training on. Basically I'd have to say it simulates a C172 very poorly and I'd say it's only use is for simulated instrument flying. Even so, it's response does not mimic my aircraft near the limits of the flight envelope -it behaves like a flying game really. Red Bull flying race? What a pile! Mark |
#7
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Tweaking the throttle on approach
Hi, just a couple of notes:
Unfortunately I tend to be impatient in the sim and I'm often still not aligned even as I cross the threshold, unless I planned to land at that airport well ahead of time. I usually come in fast because I'm making rather risky turns on the approach and I don't want to come too close to a stall. A good landing starts with a good approach. If you don't get your approach sorted out you are almost certain to stuff the landing up. What airspeed do you choose for landing? A good airspeed for crossing the fence is VSo x 1.3. Find out what your stall speed is, multiply by 1.3 and you have your speed at short finals. You can add a bit for the early part of the approach, for a 172 you might use 70-80 kt on approach, reducing to 55 kt on short finals. Whatever light aircraft you fly will be similar, can't speak for the heavies though.. If you use much more than 80kt on approach it can be difficult to get rid of the speed while still descending. Stall speeds are affected by weight, so if you are heavy the 55kt will become more like 66kt.. |
#8
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Tweaking the throttle on approach
On Mar 5, 10:11 am, Mxsmanic wrote:
Unfortunately I tend to be impatient in the sim and I'm often still not aligned even as I cross the threshold, unless I planned to land at that airport well ahead of time. I usually come in fast because I'm making rather risky turns on the approach and I don't want to come too close to a stall. If not aligned at the threshold in a real plane, you should go around. You should strive to become aligned with the centerline soon after turning onto final, and then hold it there. It can be done with practice. Don't forget you'll need a crab angle to take care of crosswind. How do you trim to a speed? Especially when you are adjusting power? Don't try to do both at the same time. Hold power constant, and adjust pitch with the yoke until you are at your desired airspeed, then apply trim until you can release the yoke without the pitch attitude (and therefore, airspeed) changing. Then with the airspeed stabilized, adjust power to change the rate of descent, small changes in power won't affect your airspeed. What airspeed do you choose for landing? You need the proper speed for your aircraft. If it's not available in the Pilot's Operating Handbook, then use an old rule of thumb, set the airspeed equal to 1.3 times the aircraft's stall speed. Your aircraft should be slowed to this speed by the time you turn final, and then hold it precisely at that speed. The normal way to hold airspeed is by trimming to that speed in pitch. Hmm ... I had not thought of working out numbers that I could reuse. Each approach has been trial and error but I haven't been noting anything. I guess I'll have to write stuff down (or at least try to remember it). I do have a few things memorized for the Baron, after hundreds of hours in it, but not as much as I probably need or could use. You will not achieve consistent landings until you can fly a stabilized approach. To do this, you need to discover the numbers for your aircraft, and then use them. To find them, I suggest you conduct some experiments in the sim. Set up your aircraft in level flight on downwind, constant speed, gear down, at 1000 ft AGL, with a medium power setting. When opposite the numbers, lower your flaps to their first setting (or 10 deg) and reduce power until you stabilize at a 500 ft/min descent rate with the airspeed at 1.5 times stall speed. Record the power setting and airspeed. Use those numbers for your initial descent from the pattern. After 30 seconds, turn base and lower flaps to the second setting and set pitch for airspeed = 1.4 times stall speed. Then turn final, lower flaps completely, and set pitch for 1.3 times stall speed. Fly it like this until you hit the ground. If you land long, then reduce power a little more next time. If you land short, add a little power next time. Keep iterating until you zero in on the right numbers. |
#10
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Tweaking the throttle on approach
Roger writes:
Learn this first with the 172, then work with the bigger stuff. I don't know if I can trust the sim's default version of the 172. The add-ons I use have a reputation for extreme accuracy, so I can be reasonably confident that they do just what the real aircraft does, but I don't know about the 172. If I can find a reputable add-on C172, maybe I'll get that sometime. That's the main reason I don't fly the 172 much. I do have an A36 Bonanza, also by Dreamfleet, but the EHSI isn't Reality XP (Reality XP is known for its 100% accurate instruments), and the EHSI on the Baron is. I guess the EHSI wouldn't matter so much for pattern work, though. Also I figure it's better to get good in a small number of aircraft than mediocre in a large number, since in real life I probably wouldn't be flying 20 different aircraft, but just two or three at most. -- Transpose mxsmanic and gmail to reach me by e-mail. |
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