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Near miss in traffic pattern


jcovington

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1 hour ago, Shadrach said:

I think Peter’s point is that while bank angle can affect AOA, they are independent of one another. Given enough altitude one could theoretically do a slow 8 point roll and attain the same AOA at every point. 

This is also true- but his argument, or at least the way I read it...is that in a descent, if you set an angle of bank, your stall speed is not faster than if you’re level.  That is not true.  The second you roll your wings, the airspeed for a given angle of attack increases in stable flight- regardless of whether one is in a climb, descent or level.

the stall occurs at the critical AoA in both cases, but the airspeed at which an aircraft stalls will be higher in the case where an aircraft has an angle of bank, regardless of whether that aircraft is descending or level.

Edited by M016576
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28 minutes ago, jaylw314 said:

Simply descending while turning does not protect you against an accelerated stall.  You only have the extra margin created by decreasing your wing loading while your nose is continuing to drop.

^yes- this

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59 minutes ago, jaylw314 said:

Not sure if I'm seeing this right, but did you make your 360 to the inside of the pattern from the base leg?  I would have thought making a 360 to the outside of the pattern would be safer?  You've presumably just cleared your right side looking for traffic on extended final, whereas you've not had a reason to scan the downwind leg behind you?

Possibly, being that near the runway there is a really small chance that another plane would be there.   And Turning right would be mostly a blind turn.  way more visibility to the left.   and I announced it.

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14 hours ago, bonal said:

So, for example  can an airplane be banked at 30 degrees to establish a turn with an understanding you will lose altitude without increasing wing loading or AOA.

Yes. In a bank the vertical lift component (that was acting straight up when at 1 g or level flight) splits to horizontal and vertical components. Assuming you don't change the amount of lift the wing is producing some of the lift that was acting to hold altitude is now acting to turn the airplane. The result of this is that now we have less of vertical component to maintain altitude.

Now hold that thought and fast forward to a low agl, low airspeed, overshot base to final turn where instead of going around the pilot wants to desperately maintain altitude and get back on final. To maintain altitude lift needs to increase and to do that pulls back on the yoke which increases the aoa. To get back on final rudders the  nose around which produces yaw with unwanted roll. 

These are all incorrect inputs hopelessly trying to correct a pattern gone bad much earlier than the overshot base to final. We need to think of the pattern from downwind to touchdown as one continuous descending turn flown according to what the wind is doing. 

 

Edited by PTK
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On 6/14/2019 at 3:52 PM, carusoam said:

What are you guys using for judging distance around the pattern on the down wind..?

  • wing tip on the runway
  • runway halfway out on the wing
  • Fuel cap on the runway, extra close
  • wing tip + four fingers, extra far
  • GPS
  • visual cues... roads, steeples, etc..

Just seeing how you measure this.

Best regards,

-a-

I use the runway edge that's closest to me placed about mid wing.

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On 6/14/2019 at 4:41 PM, PTK said:

What bank angle is not prudent? It’s ok to bank the airplane! In fact being afraid to bank and instead rudder the nose around trying to hold level flight is what kills pilots in the infamous base to final turn. It’s about time we put away these myths and teach pilots how to fly. Bank the airplane all you want and unload the wings with your elevator into a descending turn. Stall speed will not increase. It will only increase if trying to hold level flight. 

I'm afraid this is factually wrong.  Look at your POH.  Stall speed increases with bank angle because the vector of vertical lift is diminished din a bank.

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35 minutes ago, steingar said:

I'm afraid this is factually wrong.  Look at your POH.  Stall speed increases with bank angle because the vector of vertical lift is diminished din a bank.

If you are not increasing load (by maintaining altitude) I think PTK's statement is correct.

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3 hours ago, steingar said:

I'm afraid this is factually wrong.  Look at your POH.  Stall speed increases with bank angle because the vector of vertical lift is diminished din a bank.

No. That POH table assumes holding level flight. You can't speak of bank angles without also speaking of g load. Not all 60 degree banks are 2 g for example. G load is responsible for stall speed increase, not bank angle. Stall speed increases in relation to the square root of load factor. In order to have an increase in stall speed you must have an increase in load factor.

 

Edited by PTK
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On 6/17/2019 at 5:53 AM, steingar said:

I'm afraid this is factually wrong.  Look at your POH.  Stall speed increases with bank angle because the vector of vertical lift is diminished din a bank.

PTK is right and “unloading the wing” is one of the tools taught in essentially any unusual attitude recovery course (which I would HIGHLY recommend everyone take). A wing stalls when you exceed the critical AOA. If you bank the plane and pull back on the yoke to compensate for the lost vertical component of lift then you will increase stall speed. What PTK wrote in his post is that if you unload the wing (lower the AOA) then you won’t necessarily increase your stall speed.

Hammerhead turn is a good example of thinking about things in terms of AOA. Near the top of the turn you’re pointing straight up and are very slow but you are NOT stalled because the relative wind is coming from above and your AOA is small. 

Edited by ilovecornfields
Removed “to maintain level flight” to clarify post
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Perhaps a good mental image is someone trying to do a constant 2G vertical loop.  During the loop, his stall speed is exactly the same as the guy banking 60 deg in a level turn.

Another mental image is someone doing a sick-inducing 0G dive.  If you do a parabolic drop, with the nose descending the entire time, you will never stall.

 

Edited by jaylw314
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On 6/17/2019 at 9:39 AM, ilovecornfields said:

If you bank the plane and pull back on the yoke to maintain level flight while compensating for the lost vertical component of lift then you will increase stall speed.

Not necessarily to maintain level flight, though- and that’s where PTK is incorrect.  All you have to do is try to increase your turn rate by increasing load factor. You can still be in a stable rate of descent, with the intention of continuing that rate of descent.  All that’s required to increase the speed at which your airfoil will stall is setting an angle of bank.  To actually stall, all you need to do is exceed the critical angle of attack.  And here in lies the root of why an AoA indicator is far more valuable than an airspeed indicator in determining where that stall will occur.  

To put it in layman’s terms: if you bank the airplane, then increase the backstick (backyoke?) pull, your aircraft will stall at a higher airspeed than if you are wings parallel to the horizon (lift vector perpendicular to the horizon).  Pulling to “maintain level flight”, while a potential cause for an accelerated stall, is one result, but not the sole reason.  You can be in a descending turn, if you pull to increase your turn rate, and continue to reorient your lift vector for a rate of descent- you will stall at a higher airspeed than if you are wings level.  Same goes for a climbing turn.  

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1 hour ago, M016576 said:

Not necessarily to maintain level flight, though- and that’s where PTK is incorrect.  All you have to do is try to increase your turn rate by increasing load factor. You can still be in a stable rate of descent, with the intention of continuing that rate of descent.  All that’s required to increase the speed at which your airfoil will stall is setting an angle of bank.  To actually stall, all you need to do is exceed the critical angle of attack.  And here in lies the root of why an AoA indicator is far more valuable than an airspeed indicator in determining where that stall will occur.  

To put it in layman’s terms: if you bank the airplane, then increase the backstick (backyoke?) pull, your aircraft will stall at a higher airspeed than if you are wings parallel to the horizon (lift vector perpendicular to the horizon).  Pulling to “maintain level flight”, while a potential cause for an accelerated stall, is one result, but not the sole reason.  You can be in a descending turn, if you pull to increase your turn rate, and continue to reorient your lift vector for a rate of descent- you will stall at a higher airspeed than if you are wings level.  Same goes for a climbing turn.  

I agree with what you said. I think the point was that if you need to make a steeper bank, “unloading the wing” by decreasing the AOA can allow this at a slower speed without stalling. The misconception I believe we are both trying to clear up is that you stall at a certain speed or combination of speed and angle of bank. I think we both agree that this is incorrect - you stall at a certain AOA and pulling the stick back to exceed that AOA will cause a stall. Pushing the stick forward (unloading the wing) may prevent that stall.

Note: I edited the previous post you quoted. Hopefully, we are all in agreement now.

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36 minutes ago, ilovecornfields said:

I agree with what you said. I think the point was that if you need to make a steeper bank, “unloading the wing” by decreasing the AOA can allow this at a slower speed without stalling. The misconception I believe we are both trying to clear up is that you stall at a certain speed or combination of speed and angle of bank. I think we both agree that this is incorrect - you stall at a certain AOA and pulling the stick back to exceed that AOA will cause a stall. Pushing the stick forward (unloading the wing) may prevent that stall.

Note: I edited the previous post you quoted. Hopefully, we are all in agreement now.

And that's exactly the point I was trying to make. Making base and final turns can be banked safely as long as you don't increase wing loading by increased elevator in an attempt to INCREASE your RATE of turn. If you make your turn radius and rate of descent correctly to line up with the runway on the desired glide slope without the need to tighten your turn there is no problem.

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