8s on Pylon Fail
Posted by B4nAn4s@reddit | flying | View on Reddit | 45 comments
Hey everyone, I just failed my checkride today on 8s on pylon because I was changing the power setting during the maneuver. I am not sure how I should feel or go about this because I've always been taught that I can touch the throttle during the maneuver.
I was taught to stay at 100kts indicated so I can find my groundspeed to determine my pivotal altitude. Once I enter the maneuver, I keep my bank constant and vary my pitch to change my altitude and keep my pylons in sight with the visual reference line. When the pylon is ahead of me, I pitch down. When the pylon is behind me, I pitch up. When I change my pitch, my airspeed will also change, which means I change the power setting to keep myself at 100kts indicated.
Once during the maneuver, I saw that my airspeed dropped to 85kts, on its way to 70s. There was no way I was going to let the speed get that low. So is it wrong of me to add power?
I read the AFH on 8s on pylon as well as the ACS, and none of them says anything about keeping the power constant throughout the maneuver. The AFH common errors say nothing about changing power/airspeed either.
I've always been taught this way with different instructors, and no one ever tells me this is wrong.
Is there something that I am missing? Can I even contest this notice of disapproval? Or should I just accept my fate?
eSUP80@reddit
I was taught that you can make a power change, but don’t use it as a crutch and invalidate the purpose of the maneuver. My DPE concurred.
It is absolutely necessary when there is a decent amount of wind.
mild-blue-yonder@reddit
I teach set the power and leave it there. If you’re moving the power around, your airspeed and altitude are going to be all over the place and pivotal altitude are gonna be hard to chase.
What plane?
B4nAn4s@reddit (OP)
PA-28
OZZMAN8@reddit
Dog any time a student struggled with 8's it's because they were overthinking it. Set the power, forget it, use a chart for pivotal (not an equation), if that mf goes in front of your wing you dive, if it's behind you climb to let it catch up. If on your cfi ride you say those exact words. Then you say that those changes are due to changes in ground speed from going into or with the wind. Dont try explain what the wind is doing mid maneuv. If your speed is getting too fucked up from the dives and climbs it's likely you were too close to your pylons, meaning that you have to make adjustments way more abruptly. The pro move is you pick your first pylon (with the second half-picked), the dpe wont likely ask what your second is, then as you roll level pick your second even if you have to adjust slightly and rock it out. I've never heard a dpe ask for both your pylons at the start.
B4nAn4s@reddit (OP)
yeah thanks. I should keep it simple like that then. I am going to accept this failure
mild-blue-yonder@reddit
FWIW, this is a fairly common problem.
Also the method described above makes this maneuver very easy.
bhalter80@reddit
Exactly this! Even if you don't get your pivotal altitude "just right" until half way around because winds are always different just roll with it. Climb/descent so what it takes to keep the right reference with just pitch
Dogmanscott63@reddit
Thatbis what i was taught and what I teach. It is strictly changes in pitch to keep the pylon on your reference.
mirassou3416@reddit
This is a constant power maneuver
https://www.aopa.org/news-and-media/all-news/2021/december/flight-training-magazine/technique-eight-on-pylons#:\~:text=December%208%2C%202021%20By%20Jill,your%20mean%20sea%20level%20altitude.)
thatTheSenateGuy@reddit
That’s not the point of the maneuver… the point is to use ground speed to keep wing on the pylon. When you turn into the wind your ground speed slows and you are expected to use altitude changes to compensate for your slower speed (and vice versa) Using power masks this skill.
B4nAn4s@reddit (OP)
I understand where you are coming from, but can you explain this a little bit further? When I was setting up for the maneuver, I kept my speed at 100kts indicated, my GS still change based on the direction of wind (head or tailwind). So why is it bad to do it during the maneuver?
thatTheSenateGuy@reddit
So you are using your existing energy…. Your energy is your current speed and current altitude. You are managing your energy to make a figure 8 pattern around two points staying roughly a constant radius form the point and with your wing attached to the point.
The altitude is defined by your pivotal altitude; which is MPH/15 or KTS/11.3. This altitude with no wind will keep you perfectly around a point with no wind. You’ll ideally will be at constant ground speed, altitude and bank.
Now let’s add wind… wind will slow you down in a head wind condition and speed you up in tailwind. The goal is still remain with your wing or strut attached to the points. And the maneuvers per AFH is to use your pitch to adjust your altitude for your new speed. This new speed means new pivotal altitude. If you could fly with a constant head wind of 10kts as you go around the circle at 100kt your pivotal altitude will be based on 90kts now. That will result a lower pivotal altitude. Now consider if you had 10kts tailwind the whole way around you’d be higher in Pivotal. But this is not how the real world works; instead you have both but at different times in the turn. So the whole maneuver is maintain the wing/strut at the point defined by the e pivotal latte but your perfect pivot at altitude is constantly changing through out the maneuver.
This is the way I understand as a CPL, but I’m not a CFi maybe they have better ways to explain.
Mach_v_manchild@reddit
Leave the throttle. But I will say, moderate adjustments in pitch are your friend. My last commercial student used to pitch up and down so much their airspeed varied from 80-120kts. Took months to teach that out of them. Don't do that.
WhiteoutDota@reddit
Seth Lake did a great podcast to answer this: https://youtu.be/2MbS2JuAfc4?si=wW3zNcuuf18drPs7&t=1897
WhiteoutDota@reddit
Two DPEs I know, Adam Boyd and Seth Lake, will agree with your instructor that it's actually necessary to change your power during the maneuver. If you are in calm winds, it's not needed, but in heavy winds it's ABSOLUTELY NECESSARY to change power during the maneuver. Sorry you failed, I would actually say you should consider reporting the DPE to the DPE hotline on DMS.
B4nAn4s@reddit (OP)
Omg thank god someone agrees with me. I'm not going crazy after all.
WhiteoutDota@reddit
Actually, here's something even better, rather than be claiming what their opinion is: https://www.youtube.com/watch?v=2MbS2JuAfc4&t=453s
Two DPEs discussing the very question you've asked. The Adam Boyd opinion can be had on the VSL Aviation discord.
bhalter80@reddit
If the visual reference line appears to move ahead of the pylon (pylon appears to move back), the pilot should increase altitude. If the visual reference line appears to move behind the pylon (pylon appears to move ahead), the pilot should decrease altitude. Deflecting the rudder to yaw the airplane and force the wing and reference line forward or backward to the pylon places the airplane in uncoordinated flight, at low altitude, with steep bank angles and should not be attempted.
As the airplane turns toward a downwind heading, the pilot should rollout from the turn to allow the airplane to proceed diagonally to a point tangent on the downwind side of the second pylon. The pilot should complete the rollout with the proper wind correction angle to correct for wind drift, so that the airplane arrives at a point downwind from the second pylon that is equal in distance from the pylon as the corresponding point was from the first pylon at the beginning of the maneuver. At this point, the pilot should begin a turn in the opposite direction by lowering the upwind wing to the point where the visual reference line aligns with the pylon. The pilot should then continue the turn the same way the corresponding turn was performed around the first pylon but in the opposite direction.
Note that there are multiple references to changing pitch and roll but none to changing power.
B4nAn4s@reddit (OP)
Yes, if there are no references to changing power, then was I wrong for touching the throttle then?
I did the maneuver as the AFH described it. I varied my pitch based on the GS. The only difference is that I maintained 100kts indicated while changing altitude.
bhalter80@reddit
Yes! The AFH tells you what TO do
B4nAn4s@reddit (OP)
Can you tell me where in the AFH it says adjusting the throttle on entry? I just read it, but I don't see it anywhere.
"Would you also have decreased power in the descending phase to maintain 100KIAS?" - Yes, unfortunately, I did 😞
bhalter80@reddit
It's in the demo section for showing the different perspectives not in the maneuver itself
B4nAn4s@reddit (OP)
My bank was around 20ish degrees, and I still have a long way to climb with airspeed already close to the 70s. I didn't want to risk the plane stalling. Also, I thought it was wrong if your airpseed indicator changes too much like that. That's why I did what I did.
bhalter80@reddit
Your bank was too shallow too it should be 30 which would put you at around 5-6*/second rate of turn for the same load factor, meaning that even if you had a 1000FPM climb you're looking at an actual altitude gain of 150ft because the climb is only 10-15 seconds before the twailwind starts to shift.
2 observations (I know this was a rough day and this may not be entirely fair)
Work on building the precision to decide what you want the instruments to say, and making them do that while maintaining your scan and view outside. Practice the slow speed regime and understand where the corners of the envelope are it's completely safe to do at altitude. Once you understand then you'll see you were in no danger
B4nAn4s@reddit (OP)
damn banking at least 30? My bank is based on how far my pylons are from each other. They were decently spaced apart, so I didn't think banking over to 30 or more was necessary.
bhalter80@reddit
You're momentarily level crossing between pylons so spacing shouldn't factor into it aside from them being too close and not getting that segment. Are you anywhere near NH? I like teaching this maneuver :)
B4nAn4s@reddit (OP)
I just read a reply that got me thinking. When entering the maneuver, I am entering on a downwind = GS is highest = highest pivotal altitude. Makes sense
from downwind into a headwind, my pylon is in front of me. GS decreases = pivotal alt decreases (aka pitch down). However, if I pitch down, my IAS increases, doesn't it mean my GS also increases? GS increases = pivotal alt increases
keeping IAS constant lowkey makes sense tho
bhalter80@reddit
You're entering on a 45 to the crosswind so not full downwind. Once you inter ept your point and roll into the bank your be turning to crosswind so you'd be descending because of the lower GS you'd have a lower pivotal altitude as you turn from crosswind to upwind. That pitch down increases your GS and IAS over the lower pivotal altitude if you maintained level
Ant_Tall@reddit
When I went for my Cfi ride, the examiner made it very clear that he wanted to see power adjustments made during eights on pylons to maintain an indicated airspeed. The airplane flying handbook is honestly extremely vague for eights on plyons. I could argue for either side of the argument tbh.
B4nAn4s@reddit (OP)
Damn I wish I got your DPE. That was actually nice of him to mention that. I wished mine told me not to do this if he didn't like it. It's honestly an easy fix, but still hurts that I failed for it.
This seems very DPE dependent
Ant_Tall@reddit
Yeah, if he failed you just on power changes I would say that’s bs. Not sure why most people argue against it. It’s the same reason you maintain a constant indicated airspeed during s turns and turns around a point. Your ias is your constant and your groundspeed is your variable. The sole purpose of eights on pylons is to demonstrate the correlation between groundspeed and pivotal altitude. When you pitch up and down during the maneuver you’re changing your ias which will obviously change your gs as well. Like I said I have my argument for keeping power constant as well too… Sucks but just move forward.
B4nAn4s@reddit (OP)
I totally agree with this. I think your explanation correlates with where I was coming from. This got me thinking again about this checkride lol.
AHarmlessCat@reddit
You should be coordinating your pitch/altitude and bank angle to compensate for winds and the changes in pivotal altitude throughout the maneuver. If you vary your power, that changes your speed and therefore pivotal altitude and defeats the purpose of the maneuver.
B4nAn4s@reddit (OP)
gotcha. I understand now. Thanks
mambosan@reddit
Everything you said is accurate except for staying at 100 KIAS. Your airspeed is naturally going to fluctuate as you climb/descend to keep the radius around the pylons constant. If it’s done right (including entering in a tailwind) you should end up roughly at your pivotal altitude when you level out to change to the next pylon without touching the power
B4nAn4s@reddit (OP)
Ahhh ok thank you for this
pballer2oo7@reddit
That's completely incorrect. Your airspeed should change.
B4nAn4s@reddit (OP)
My GS still changes at 100 indicated, is that not correct?
pballer2oo7@reddit
Trying to maintain airspeed during 8s on pylons is not correct.
bhalter80@reddit
That is very very not correct. The point of the maneuver is that as you get a TW you climb HW you descend which keeps your _ground speed_ at your entry ground speed. That's why this is the one ground ref maneuver where you enter roughly crosswind rather than downwind so your entry GS and altitude is what you should exit with
JPower96@reddit
You're saying that climbing and descending keeps your ground speed the same as at entry, however, if your ground speed is the same as it was at entry, then your pivotal altitude is ALSO the same as it was at entry.
Getting a bit nitpicky, but the way I look at it is this: transitioning from TW to HW, your GS will decrease, which means the pivotal altitude decreases. You descend, your airspeed (and consequently, GS) will increase slightly as you simultaneously descend. So with no change in airspeed, you might need to descend 400 feet, but with your increasing airspeed, maybe you only need a 200 foot descent to keep your pivotal altitude.
It's late, and I'm not sure if I'm explaining my point well. Simply put, I'm just pointing out that your ground speed should NOT remain perfectly steady, otherwise there wouldn't be a need to climb or descend. Pivotal altitude would be unchanged.
B4nAn4s@reddit (OP)
I agree with what you said. GS will decrease in a HW and increase in a TW. That is still the case if I keep my indicated at 100kts, my GS still changes, and I continue to change my pitch based on GS. So was I still wrong for this?
bhalter80@reddit
I agree with you the end result is the same either your pivotal altitude is lower because of the lower GS or you use the dive to maintain the GS.
I looked up the AFH version and yours is what's quoted
bobnuthead@reddit
Your pitch should change, with the intent of changing altitude, as a result of changing ground speed. Setting the power and leaving it should allow you to enter and deal with just a few changing variables.
I’ll be honest, I’ve been guilty of cheating and adding a bit of power subtly, only when I’m coming around to finish the maneuver and find I’ve lost excess RPMs and altitude. I try to avoid adjusting the throttle whenever possible though, it shouldn’t generally be necessary.
FWIW, I’ve seen debate over the years about 8 on pylons being fixed power or not. The ACS is vague, and referring to the AFH seems to hint at fixed-power by only discussing adjustments in pitch, bank, and rudder to complete the maneuver.
rFlyingTower@reddit
This is a copy of the original post body for posterity:
Hey everyone, I just failed my checkride today on 8s on pylon because I was changing the power setting during the maneuver. I am not sure how I should feel or go about this because I've always been taught that I can touch the throttle during the maneuver.
I was taught to stay at 100kts indicated so I can find my groundspeed to determine my pivotal altitude. Once I enter the maneuver, I keep my bank constant and vary my pitch to change my altitude and keep my pylons in sight with the visual reference line. When the pylon is ahead of me, I pitch down. When the pylon is behind me, I pitch up. When I change my pitch, my airspeed will also change, which means I change the power setting to keep myself at 100kts indicated.
Once during the maneuver, I saw that my airspeed dropped to 85kts, on its way to 70s. There was no way I was going to let the speed get that low. So is it wrong of me to add power?
I read the AFH on 8s on pylon as well as the ACS, and none of them says anything about keeping the power constant throughout the maneuver. The AFH common errors say nothing about changing power/airspeed either.
I've always been taught this way with different instructors, and no one ever tells me this is wrong.
Is there something that I am missing? Can I even contest this notice of disapproval? Or should I just accept my fate?
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