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Eights on Pylon

Old 07-12-2014, 04:13 PM
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Default Eights on Pylon

Just looking for some reply's or advice i should say. I took my cfi check ride yesterday had a lovely 10 hour oral. I took a discontinuance and the flight is next week. However my inspector didn't like my presentation of eights on pylons. In my presentation I said we calculate an initial pa based on our tas in a no wind environment. However since we have a wind today we use gs2/11.3 to get our pa. So then i proceeded to show where we will be the fastest/ highest/ and slowest/ lowest. I guess this is all wrong because he said gs doesn't change in the maneuver because if done correctly your speed remains the same because when you climb in the maneuver your gs decreases and when you descend your gs increases therefor gs remains the same so you never have a highest or lowest point was his theory. Everywhere you look it is taught using gs that's how i did my commercial as well and now its some kind of big issue. Not really sure how to go about doing this maneuver in the air now since i have always done it based on gs.
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Old 07-12-2014, 04:44 PM
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Do it the way you've been doing it. If it looks right in the air, it is right. If he brings up the issue of groundspeed again, have a copy of Airplane Flying Handbook on hand.

"The pivotal altitude is critical and will change with variations in groundspeed. Since the headings throughout the turns continually vary from directly downwind to directly upwind, the groundspeed will constantly change. This will result in the proper pivotal altitude varying slightly throughout the eight. Therefore, adjustment is made for this by climbing or descending, as necessary, to hold the reference line or point on the pylons. This change in altitude will be dependent on how much the wind affects the groundspeed."
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Old 07-12-2014, 05:03 PM
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Yes I did show him that as well and he continued to say its no based on gs, seems like its his way or the highway i will just do it as i have been the entire time
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Old 07-12-2014, 05:17 PM
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Originally Posted by Mistek89 View Post
Yes I did show him that as well and he continued to say its no based on gs, seems like its his way or the highway i will just do it as i have been the entire time
Show him where it's at in the FAA reference (airplane flying handbook). Stick to your guns. Ask him if the AFH is wrong (it's not).
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Old 07-12-2014, 05:29 PM
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This seems fishy. (What the faa guy is claiming)
Its true that gs squared divided by 11.3 = pivotal altitude. And that due to acceleration during decent, decelerating during ascents, the pivotal altitude you computed wont ever be true. But it will be close. Sometimes as low/high as 50% of what you computed.

Maybe he was trying to get a rise out of you, and get you to "prove" to him that your way is correct.? Just like you would need to with a student. I could see an inspector doing that. Kind of dumb and an excessive use of roleplaying but in their mind they are the student, you are the teacher. So treat them like one.
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Old 07-12-2014, 06:11 PM
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I am just looking forward to being done with this
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Old 07-12-2014, 06:32 PM
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Originally Posted by Aviator89 View Post
This seems fishy. (What the faa guy is claiming)
Its true that gs squared divided by 11.3 = pivotal altitude. And that due to acceleration during decent, decelerating during ascents, the pivotal altitude you computed wont ever be true. But it will be close. Sometimes as low/high as 50% of what you computed.

Maybe he was trying to get a rise out of you, and get you to "prove" to him that your way is correct.? Just like you would need to with a student. I could see an inspector doing that. Kind of dumb and an excessive use of roleplaying but in their mind they are the student, you are the teacher. So treat them like one.
Or maybe how you can estimate the pivotal altitude for the start of the maneuver, which positions you, but as you do it the "calculation" goes out the window, as you simply adjust pivotal altitude as the GS changes. That's all the calculation is doing for you, and TAS+wind=estimate of pivotal for the start and that's about it.
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Old 07-12-2014, 11:08 PM
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I guess this is all wrong because he said gs doesn't change in the maneuver because if done correctly your speed remains the same because when you climb in the maneuver your gs decreases and when you descend your gs increases therefor gs remains the same so you never have a highest or lowest point was his theory.
So hes basically saying its nothing more than a figure 8? So lets get this straight...he's saying because your gs remains constant, your altitude won't change ("you never have a highest or lowest point", in his words), but your gs cant remain constant without climbing or descnding.

Originally Posted by Aviator89

Maybe he was trying to get a rise out of you, and get you to "prove" to him that your way is correct.? Just like you would need to with a student. I could see an inspector doing that. Kind of dumb and an excessive use of roleplaying but in their mind they are the student, you are the teacher. So treat them like one.
This.
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Old 07-12-2014, 11:29 PM
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Originally Posted by Mistek89 View Post
Just looking for some reply's or advice i should say. I took my cfi check ride yesterday had a lovely 10 hour oral. I took a discontinuance and the flight is next week. However my inspector didn't like my presentation of eights on pylons. In my presentation I said we calculate an initial pa based on our tas in a no wind environment. However since we have a wind today we use gs2/11.3 to get our pa. So then i proceeded to show where we will be the fastest/ highest/ and slowest/ lowest. I guess this is all wrong because he said gs doesn't change in the maneuver because if done correctly your speed remains the same because when you climb in the maneuver your gs decreases and when you descend your gs increases therefor gs remains the same so you never have a highest or lowest point was his theory. Everywhere you look it is taught using gs that's how i did my commercial as well and now its some kind of big issue. Not really sure how to go about doing this maneuver in the air now since i have always done it based on gs.
I stopped reading after you said you got a 10 hour oral. Your POI is a DB.
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Old 07-18-2014, 10:23 PM
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Well he failed me on the flight and on eights on pylons because I established my pa based on my entry gs how I've always done it. He said if I can't do something as simple as figure out how to do an eight on pylon I might as well look to do something else other then instructing. Really don't understand his deal I either have to retake the flight with him or go out of district and do the oral all over again. This whole testing process is a joke all my buddy's that are cfis don't understand what's going on here .
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