Eights on Pylons

MarkL

MarkL

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MarkL
My friends,

What would you consider the airspeed for entry into an Eight on Pylon?

Va ? But as you descend you would exceed Va to hold the pylon or is that ok as long as the air isn't turbulent? It seems that even on the nicest days, I've had 20-30 knot winds at pivotal altitudes, so we are talking 500 feet climbs and descents to hold pivotal altitude, and to lose that much altitude in a descent around the backside is going to really push the airspeed up.

Commercial and CFI PTS both do not mention what the appropriate airspeed for entry is.... neither does the AFH or Kershner.
 
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Take my words with a grain of salt but this is my understanding of eights on pylons. Va is the airspeed at which most flight training maneuvers are performed at. To be more specific, each of the books I've looked in for the answer all say "at the recommended entry speed." Do understand also that Va does change depending on weight and unless you can fly at exactly that airspeed, a few knots to keep up with pivotal altitude shouldn't hurt the airplane even if its a little bumpy out. I don't think you'll be doing full deflection of controls or flying in the mountains during this manuever. During perfect conditions and flying skills, pivotal altitude should stay about the same throughout the manuever. I'm assuming you can do eights on pylons at any airspeed but I would think completing two turns within 3/4ths of a mile would be awefull tricky the faster you go.

With a climb, descend, headwind, or a tailwind, you're groundspeed can and will change thus your pivotal altitude will change as well. It is also very possible to have wind speeds that require pivotal altitude changes that outperform your airplane. I'd stay on the ground that day! The PTS just requires you to understand how to find and keep pivotal altitude, its up to your instructor to teach you a good airspeed. All of mine have told me Va. If it helps even more, I passed my Comm checkride telling the DE I was going to use Va.
 
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If VA is the chosen entry speed, isn't it reasonable to allow ±10 knots or maybe even just ±5 knots as a common commercial standard? None are specified. If winds are gusty, then it could be argued exceeding VA would be forbidden.

As far as entry altitude, that's tied to TAS to arrive at pivotal altitude.

With stronger winds, I'm not sure how you can avoid the speeds that may result in a steeper pitch down. The only thing I can think of is use a wider radius which would relax the bank angles required for the extended lateral line of the wing pointed to the pylon.
 
No speed is specified. If you're having to dive to where you exceed Vno, I obviously don't think I'd fight the winds that day. It just isn't worth it when you're attempting to fine tune flying skills, not seeing how much the wind can kick your butt.

Pivotal altitude is based on Groundspeed. TAS can stay the same whether you have a tailwind or headwind.
 
Tim,

VA is what I figured all along but according to a local examiner, the second you start descending on that first turn into the wind, you will exceed VA so it is best to start with a cushion on that. Apparently one has to determine how much airspeed will increase during the maneuver and make sure that at it's peak, it does not exceed VA. At least according to the examiner.

Ken,

You could ease back on the bank angle on a windy day and do a wider maneuver but the commercial PTS does say that steepest bank should be between 30 and 40 degrees. So that will limit how shallow the turn can be.

Tris,

TAS would change depending on if you are descending or climbing. My understanding is this is a constant power maneuver. To be sure I am rechecking the AFH, but I've always done it this way. If you could adjust power, you could theoretically keep GS constant and thus your maneuver would be at a constant altitude since pivotal altitude is a direct result of groundspeed.
 
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Is there a standard that says airspeed must not exceed Va during this manuever? I don't have the PTS, again, I'm just going by the guide, which is the only place I've seen a speed mentioned for this manuever.

This isn't a high-G manuever, so I'm not sure why you'd be limited to Va.
 
Yes I know, sorry I didn't specify "except in climbs or descents." In no wind conditions, its still true. But pivotal altitude is still based on groundspeed. TAS changes because of the climb or descent needed to maintain pivotal altitude due to the change in groundspeed.
 
Tim I fully agree. So does my CFI.

In fact, I've always entered the maneuver at VA and never gave another thought to it until apparently it ran afoul of an examiner.
 
VA is what I figured all along but according to a local examiner, the second you start descending on that first turn into the wind, you will exceed VA so it is best to start with a cushion on that.
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Sounds like yet another idiotic examiner who needs to be beaten with FAA manuals.

There is absolutely no reason why exceeding Va in this maneuver is a problem. The PTS makes no mention of such a requirement, and the AFH says the maneuver is to be flown at "normal cruising speed".
-harry
 
My friends, at this time I am not liberty to express my true frustrations on the issue at hand, but have faith, soon I will.:eek:

Ken and I have a behind the scenes bet going on, what is the general consensus-- Is this a constant power maneuver?
 
yea the speed you enter doesnt really matter. it should be fast enough so that your pivotal altitude is higher than 500 AGL (unless you are doing your commercial in Porterfield) but otherwise I see no reason for an artificial limit at Va.
 
MarkL said:
My friends, at this time I am not liberty to express my true frustrations on the issue at hand, but have faith, soon I will.:eek:

Ken and I have a behind the scenes bet going on, what is the general consensus-- Is this a constant power maneuver?
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constant power makes it a lot easier, IMO
 
It was definitely constant power when I did it. You vary pitch and bank, but that's it. Touching the power during the manuever was a no-no with my instructor.
 
i suppose you could introduce power changes into the manuever, but good luck making the correct changes to all of the other flight controls to keep the manuever symmetric with speed and altitude. I guess you would have to make corresponding power changes at corresponding points in the manuever. seems to me that it would be a lot simpler to just leave it alone.
 
Yes, it's constant power, and no, it doesn't matter if you exceed Va unless you get very silly with the controls and pull more than the legal g-limit, probably 4.4 g's, or exceed Vno (or into the yellow arc in turbulence).

And I, too, would like to find out the basis on which that examiner says Va is not to be exceeded during a Pylon 8 on a Commercial practical test.

TASK: EIGHTS ON PYLONS (ASEL and ASES)
REFERENCE: FAA-H-8083-3.

Objective. To determine that the applicant:​

1. Exhibits knowledge of the elements related to eights on pylons.
2. Determines the approximate pivotal altitude.
3. Selects suitable pylons, that will permit straight and level flight, between the pylons.
4. Enters the maneuver at the appropriate altitude and airspeed and at a bank angle of approximately 30° to 40° at the steepest point.
5. Applies the necessary corrections so that the line-of-sight reference line remains on the pylon.
6. Divides attention between accurate coordinated airplane control and outside visual references.
7. Holds pylon using appropriate pivotal altitude avoiding slips and skids.​
Click to expand...
 
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Ron Levy said:
Yes, it's constant power, and no, it doesn't matter if you exceed Va unless you get very silly with the controls and pull more than the legal g-limit, probably 4.4 g's, or exceed Vno (or into the yellow arc in turbulence).
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Most all my Eights have been with constant power. For the first time on other day while doing Eights, we had winds that were getting up there close to thirty knots so my pitch down would be greater with a greater resulting airspeed. I saw my speed going up enough (~125 in a Cutlass) I did pull power by a couple inches. Vno was another twenty up but I didn't want to get any where near that, particularly in a low-level maneuver.

Fortunately, winds will be fairly mild tomorrow and expected to be so on Sunday as well.

And I, too, would like to find out the basis on which that examiner says Va is not to be exceeded during a Pylon 8 on a Commercial practical test.
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Ditto.

Here's a related question... on tasks/maneuvers that do not specify a tolerance or specific criteria such as airspeed or altitude, is it fair to apply the use of the Airplane Flying Handbook (if discussed within a given task) as if it were part of the PTS?
 
KennyFlys said:
I finally just watched... great video and demonstration but...

Somebody goofed on the formula! It's at 1:11 into the video.
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If you are talking about the GS thing, I have seen it both ways. We argued this one for a couple of hours it seems at the school where I did my CFI. I personally feel GS is a more accurate way to calculate pivotal altitude, problem is you don't know what you actual GS will be before hand. Later in the video they talk about some liking to calculate pivotal altitude on the highest and lowest expected GS. Sounds like over kill to me.

Here is a quote from an article Kershner did for AOPA:
"The pivotal altitude may be found by the equation (V2 knots)/11.3.
The V is the relative velocity to the pylon (true airspeed in no-wind conditions, ground speed when the wind is blowing)."

http://www.aopa.org/asf/publications/inst_reports2.cfm?article=5370
 
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Don Jones said:
If you are talking about the GS thing, I have seen it both ways. We argued this one for a couple of hours it seems at the school where I did my CFI. I personally feel GS is a more accurate way to calculate pivotal altitude, problem is you don't know what you actual GS will be before hand. Later in the video they talk about some liking to calculate pivotal altitude on the highest and lowest expected GS. Sounds like over kill to me.

Here is a quote from an article Kershner did for AOPA:
"The pivotal altitude may be found by the equation (V2 knots)/11.3.
The V is the relative velocity to the pylon (true airspeed in no-wind conditions, ground speed when the wind is blowing)."

http://www.aopa.org/asf/publications/inst_reports2.cfm?article=5370
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Don, thanks for the reference. I've read a lot more stuff by him since he's been gone. Given what little exposure I've had of his material and the great influence, he must be one of the most missed knowledge sources in aviation.
 
KennyFlys said:
Don, thanks for the reference. I've read a lot more stuff by him since he's been gone. Given what little exposure I've had of his material and the great influence, he must be one of the most missed knowledge sources in aviation.
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Truer words will never be spoken, sigh
 
KennyFlys said:
If VA is the chosen entry speed, isn't it reasonable to allow ±10 knots or maybe even just ±5 knots as a common commercial standard? None are specified. If winds are gusty, then it could be argued exceeding VA would be forbidden.

As far as entry altitude, that's tied to TAS to arrive at pivotal altitude.

With stronger winds, I'm not sure how you can avoid the speeds that may result in a steeper pitch down. The only thing I can think of is use a wider radius which would relax the bank angles required for the extended lateral line of the wing pointed to the pylon.
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There is no speed standard to match during the manuver as by the nature of the manuver, the speed will change, and that speed will vary with the wind speed as that is the determinant for maximum pitch.
 
if you are flying the manuever correctly, the pivotal altitude will work itself out anyway. calculating beforehand is just to get you in the ballpark.
 
Ralph Butcher had an article about Eights On Pylons in the Nov 2007 issue of AOPA Flight Training. He used pivotal altitude = ((ground speed in knots)^ 2)/11.35 . He says "start the maneuver as shown in the illustration using slow cruise airspeed" and calls for a reduction in power to 14 inches of manifold pressure or 1,400 rpm starting the first circuit. After that, he doesn't call for any power changes.
 
KennyFlys said:
... on tasks/maneuvers that do not specify a tolerance or specific criteria such as airspeed or altitude, is it fair to apply the use of the Airplane Flying Handbook (if discussed within a given task) as if it were part of the PTS?
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If the AFH is referenced in the PTS (as it is on Pylon-8's -- see above), yes.
 
tonycondon said:
if you are flying the manuever correctly, the pivotal altitude will work itself out anyway. calculating beforehand is just to get you in the ballpark.
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...and the only time the ballpark is important is during the entry...since the PTS requires you to compute an "approximate" pivotal altitude, I would compute it for the estimated groundspeed at the point of entry.

If you really feel the need to refine it just prior to maneuver entry, you simply say to the examiner, "Well, i see my groundspeed is 10% faster than anticipated, so I'm going to bump up my entry altitude 21%, since pivotal altitude is based on the square of speed."

Fly safe!

David
 
Hi all,

I have just come from the field and have some notes to share.

This is for the Arrow. We tried Eights on Pylons at several power settings at 2500 RPM.

16" gave us 108 mph in S&L flight
18" gave us 114
20" gave us 128

At 16", we were doing pivotal altitudes down to 500 feet AGL on upwind.

The article mentioned above that was in FT magazine mentions 14", and that is going to push you to an unsafe altitude. The wind today was 20 mph, but had it been any higher I think 14" would have forced us to go down to 300 feet AGL or less, and that is nuts.

We decided 19-20" was good and our airspeed varied between 100-150 mph. At no time were we in the yellow arc. Pivotal altitudes ranged from 600 to 1000 feet AGL.

Which is what I was using before ..... sigh.
 
Ron Levy said:
Yes, it's constant power, and no, it doesn't matter if you exceed Va unless you get very silly with the controls and pull more than the legal g-limit, probably 4.4 g's, or exceed Vno (or into the yellow arc in turbulence).

And I, too, would like to find out the basis on which that examiner says Va is not to be exceeded during a Pylon 8 on a Commercial practical test.
Click to expand...

If the manuver was never seriously in doubt then I cannot fathom his perverted concept of 8's on pylons. It sound like you did a great job of demonstrating the required knowledge of pivitol altitude..this is where many people mess that on up....this examiner is a dirty rat for sure.
Best of luck Mark
 
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Today, I had the pleasure of a lengthy chat with my CFI DPE on several things. Among them was Eights on Pylons.

The specific question I asked was... "Is it intended Eights on Pylons are to be performed at a constant power setting?"

He said, "Generally, yes. But there are exceptions." Strong wind conditions are one such exception. He would rather see an adjustment of power rather than excessive speed beyond Va.

He further pointed to the PTS regarding "good flying conditions." That is on page 10 in the Commercial Pilot PTS. It states:

Unsatisfactory Performance

The tolerances represent the performance expected in good flying
conditions. If, in the judgment of the examiner, the applicant does not
meet the standards of performance of any TASK performed, the
associated AREA OF OPERATION is failed and therefore, the practical​
test is failed.
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As usual, it becomes his judgment call. Obviously, not all DPEs are going to rule the same on a given task. I think I'm fortunate this DPE is much more objective and seeks out more than just pure "letter of the law" PTS performance.

He also agreed with Ron on the issue of AFH and PHAK becoming a tool by which to judge a PTS task that may not include a criteria that is in those training books.
 
KennyFlys said:
on tasks/maneuvers that do not specify a tolerance or specific criteria such as airspeed or altitude, is it fair to apply the use of the Airplane Flying Handbook (if discussed within a given task) as if it were part of the PTS?
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Not only fair, but...required! The teaching of all maneuvers is supposed to be in accordance with the AFH. That's what you are supposed to teach and use as a reference. And as an instructor, you see in the CFI PTS that "instructional knowledge" means being able to use the appropriate reference for the task.

Most of the variations on maneuvers and procedures that we encounter, from instructor to instructor or school to school, is because of "verbal instruction", instead of "book instruction". Individual instructors teach the way their instructor taught instead of teaching it from the AFH. If you teach it from the AFH, and the PTS, it will be more standard.
 
nosehair said:
Not only fair, but...required! The teaching of all maneuvers is supposed to be in accordance with the AFH. That's what you are supposed to teach and use as a reference. And as an instructor, you see in the CFI PTS that "instructional knowledge" means being able to use the appropriate reference for the task.

Most of the variations on maneuvers and procedures that we encounter, from instructor to instructor or school to school, is because of "verbal instruction", instead of "book instruction". Individual instructors teach the way their instructor taught instead of teaching it from the AFH. If you teach it from the AFH, and the PTS, it will be more standard.
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My Chief CFI has never sat down with me in a CFI ground lesson without at least five books... AFH, PHAK and the PTS for CFI, PPL and CPL.

Those books were only a small part of the some seventy-five pounds I'd lug upstairs to meet with him.
paperasse.gif
 
Don Jones said:
Here is a good video presentation about 8's on. Pretty well done.

http://www.youtube.com/watch?v=12MF1L5gcdw
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This is part of a whole series that the UND Aerospace team put out. It's actually a video podcast you can subscribe to in iTunes called UND Aerocast. They have all of the CSEL maneuvers, and a few private ones as well. The latest one was a spotlight on their new SR20's.
 
taters said:
If the manuver was never seriously in doubt then I cannot fathom his perverted concept of 8's on pylons. It sound like you did a great job of demonstrating the required knowledge of pivitol altitude..this is where many people mess that on up....this examiner is a dirty rat for sure.
Best of luck Mark
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In talking to my CFII who did my IR for me 8 years ago, turns out he taught this particular FSDO examiner for his original certificates when he was younger, and my CFII can't figure out why he would think a low power setting would be required for Eights.

But I did the recheck with a different examiner and I am now CFI. I used the same power setting as I did the first time and entered the manuever at the same airspeed as the first time and saw the same variations in TAS and altitude as the first time and no problems.

I am just dumbfounded as to how two FAA examiners can interprete the manuever so differently.
 
Some FSDOs had/have policies that essentially dictate a high first-time failure rate for the initial CFI. Like the "performance measures that aren't quotas" for cops and speeding tickets, the result is a perceived need on the part of the inspector to find SOMETHING on which to bust an applicant.

Glad your retest went well!
 
MarkL said:
I am just dumbfounded as to how two FAA examiners can interpret the maneuver so differently.
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As we discussed previously on Yahoo, your first DPE believed in constant power. I don't know what your second DPE expected but then you had much calmer winds.

During my ride, the wind ended up being about thirty degrees off between what I experienced at 4,000 and down at 1,700 where I began Eights. As a result, I started getting lower than I would have liked during the upwind segment so I did add a tad power. That kept up my ground speed without having to descend further. The DPE said nothing and I already knew from a previous conversation he'd rather see an adjustment for safe maneuvering rather than just continue maneuvering yourself into the ground.

While he didn't say this, the impression I got from my several experiences with him during oral and other conversations was... he'd rather see a safe operation and a thorough understanding of how the maneuver should be taught and performed as much or more than simply a maneuver within PTS. You won't achieve perfection every time but setup, proper procedure, correction and safety are as important as the PTS. Without them, the PTS is meaningless.

My last maneuver was technically a bust. On a Power-off 180, I had put the gear down on the previous landing and left it down. I had to do a couple 360's on downwind to allow a CRJ to land before I could get a clearance for a short-final. I turned in, waited until centerline for full flaps but was still high. I pushed rudder into a forward slip so hard, I turned off the headset control in the side pocket with my calf. I crossed still just a tad fast, maybe five knots. It became a fine line between flaring with that extra speed and floating so I stayed barely nose high. I touched down just beyond the two-hundred, maybe another 30-50 feet.

Here I had a good flight, all went well and I blew the last one. I was not a happy camper. I continued to taxi on down and was turning off the runway when he suddenly says, "That looked like about two-hundred, didn't it?" I thought he might give me a pass but I wasn't going to lie about my performance. I replied, "I'd have liked it a lot shorter. If I had pulled flaps sooner, I'd have had it."

At that point he says he'll need my log book to sign it. I'm thinking, "I passed? How did that happen?!?!?"
eek.gif


Something the DPE wasn't happy with had to do with another guy who came with me. Tim had taken his commercial ride the day before in 29kt winds. He blew the Power Off 180 and turned too far out, coming well short of the mark. He split the ride with me so he could do that maneuver and get his CPL.

Before we left Atlanta, something made me ask if he had his 8710. He said his CFI told him he didn't need one. Then, I saw the pink slip in his hand with other papers. It clearly said, "Notice of Disapproval." I asked his CFI. The CFI said an 8710 wasn't required. While I walked back to speak with the school owner, Tim called the DPE. Both said he needed one. Then, the owner tells the CFI to call the DPE. Again, the CFI is told he needs an 8710.

DPE's like to see the paperwork they are required to submit to the FAA, including the 8710. More so, they like to see the required flight time. The previous week, the DPE sent an instrument rating candidate back home to his school. Why? The instrument candidate showed up with his 8710... with 15.6 cross-country hours indicated, verified by his log book. :rolleyes:

Mark, it sounds like your first DPE had a "Do it within the PTS or die" kind of attitude. But, after it's all said and done... we both made it!
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Mark, I'm confused - was your CFI ride with an inspector or DPE? Was it your initial instructor rating?

Here in the DC area all initial instructor rides are with an inspector, unless something makes it impossible for them to do it in the allowable time window. DPEs can do add-on ratings after an instructor certificate is earned.
 
Correct. With the FSDO for my initial. My CFII will be with a DPE. And despite all my complaining it was a positive experience and I learned alot from both guys who adminstered the exam. I will post a write up of the whole ordeal shortly. I had emails I shared with a few other CFI students out here about my experiences.
 
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