Stall base to final.. question on the pattern

francisco collazos said:
So I have been wondering if stalls from base to final are more likely if the downwind lag is closer to the airport? The pilot makes the turn to base and then has to turn final when closer to the approach end therefore over/undershooting the approach. So my question is based on this assumption,if this is one of the leading causes of crashes wouldn't it make more sense to teach wider patterns? Of course people are going to say to stay close to the airport in case of an engine out but it seems like we are worried about something that would happen less frequently i.e engine out vs. stall. I mean we are worried about an engine out near an airport.
Please correct me if i'm wrong.
Click to expand...

This kinda went into a discussion of how different people fly the pattern. Back to the original question, you have a couple of assumptions baked into that question. First, that it's easier to overshoot the approach if you're closer. Second, that if someone overshoots the approach they're more likely to stall/spin. Third, that stall/spin on final is a leading cause of crashes. Forth, that standard patterns are only done to reduce the risk of not making the field if an engine quits.

Here's my take on those:
1 - That seems plausible.
2 - I don't believe this is true. Stall/spin is caused by bad technique. To me, it's a training issue, not a situational issue.
3 - This isn't true at all, see above.
4 - This isn't true, either. There are multiple reasons not to fly a large pattern, one of which is that you're much more likely to come in too shallow, and from what I've seen can lead to pilots either coming in too fast, which easily results in a bad landing, or dragging the airplane in at a high AOA, which can lead to some entertaining landings as well.

Or in other words, my take is that flying extra large patterns as a way to compensate for poor technique on base/final turn isn't going to reduce the risk of that turn causing problems, but it IS likely to cause other problems. It's a substitution of one bad technique for not being able to do another.

Just my 2 cents...stay safe up there!
 
A stall occurs when you exceed the critical AOA. That’s is controlled by elevator. Bank angle has nothing to do with it Other than people have a tendency to pull back on the elevator to keep the nose up at higher bank angles.
 
Stewartb said:
You use 60° banks in the pattern? Ya, me neither.
Click to expand...
Not usually, but base to final turn stalls occur when things get out of whack. Like a tail wind on base so you overshoot, tighten the turn to not overshoot and end up with 60 degrees of bank.
 
Jeff767 said:
A stall occurs when you exceed the critical AOA. That’s is controlled by elevator. Bank angle has nothing to do with it Other than people have a tendency to pull back on the elevator to keep the nose up at higher bank angles.
Click to expand...

Let's see, a level 60 degree bank turn requires 2G. So you need to increase AOA to increase G to make the turn. So yes, bank angle DOES have something to do with it.

You contradict yourself by saying that people pull back to keep the nose up at higher bank angles. :D
 
Any time you bank, you are trading some vertical lift for some horizontal lift. Convert too much vertical lift to horizontal lift and you stall out of the sky. Bank angle has very much to do with potential stalls. AOA automatically bakes bank angle into the equation, so while you are incorrect about the elevator, you are correct about AOA.
 
Domenick said:
Any time you bank, you are trading some vertical lift for some horizontal lift. Convert too much vertical lift to horizontal lift and you stall out of the sky. Bank angle has very much to do with potential stalls. AOA automatically bakes bank angle into the equation, so while you are incorrect about the elevator, you are correct about AOA.
Click to expand...
So I can't do an aileron roll without stalling?
 
Domenick said:
Any time you bank, you are trading some vertical lift for some horizontal lift. Convert too much vertical lift to horizontal lift and you stall out of the sky. Bank angle has very much to do with potential stalls. AOA automatically bakes bank angle into the equation, so while you are incorrect about the elevator, you are correct about AOA.
Click to expand...
This may only be semantics but here goes. Lift is lift and it is a force generally perpendicular to the surface of the wing. Lift can have either a horizontal component or a vertical component or some combination of the two depending on bank angle. In other terms, lift is a vector sum of the vertical vector and the horizontal vector. You can have all horizontal lift and never exceed the critical angle of attack--you will spiral into the ground and never stall. A graveyard spiral is just that. A graveyard spin occurs when a pilot sees he's descending too fast and speed is building in a graveyard spiral so he pulls back on the stick to slow the rate of descent and speed but due to not lessening the bank, he exceeds the critical angle of attack and stalls. Both will kill you.
 
Lindberg said:
So I can't do an aileron roll without stalling?
Click to expand...
Yup. No problem. But when most here refer to banking, they're talking turning, not aerobatics. No aerobatics in the pattern; that's for airshow performers.

The banking as a means of turning raises the load factor. Can't get away from that. It's the horizontal component of the lift that changes the direction of flight. Note below how the Total Lift has to increase as the turn steepens, and increased AOA or more speed has to make that up. More AoA means elevator input. More speed means a larger turn radius that might require an even steeper bank to conform to the intended flight path.

1690821133185.png
 
Lindberg said:
So I can't do an aileron roll without stalling?
Click to expand...
The wing never stalls because it never exceeds critical AoA, because the pilot reduces elevator input as the bank angle increases. The aircraft can momentarily maintain a somewhat level flight path because the side of the fuselage provides lift. The pilot increases rudder input through knife edge, which increases AoA and lift. Key word is "momentarily".
 
Dan Thomas said:
Yup. No problem. But when most here refer to banking, they're talking turning, not aerobatics.
Click to expand...
Ok. But the post I responded to says nothing about turning. And this is how misconceptions get perpetuated. Banking, does not by itself increase the stall speed or make you stall.

I can absolutely do 30°, 45°, 60° of bank in the pattern, without stalling or spinning.

Yet sitting by the runway, I regularly see students at 20° of bank turning final with rudder because they've been told steep banks in the pattern will kill them.
 
Lindberg said:
Yet sitting by the runway, I regularly see students at 20° of bank turning final with rudder because they've been told steep banks in the pattern will kill them.
Click to expand...
Which simply reveals serious deficiencies in the training. Gimmicks won't fix that. Making it harder to get a CFI ticket will fix it.

It doesn't take any longer to teach a student the right stuff than it does to teach him/her the wrong stuff. But if the CFI doesn't have the right stuff, how is he going to teach it?
 
Ed Haywood said:
The wing never stalls because it never exceeds critical AoA, because the pilot reduces elevator input as the bank angle increases. The aircraft can momentarily maintain a somewhat level flight path because the side of the fuselage provides lift. The pilot increases rudder input through knife edge, which increases AoA and lift. Key word is "momentarily".
Click to expand...
Yes.

But an aileron roll is an all positive G maneuver. You raise the nose, reduce back pressure and roll.

What you are describing is a slow roll. There you are doing a roll along a line, and use rudder and forward elevator to maintain staight flight while rolling.
 
Pinecone said:
Yes.

But an aileron roll is an all positive G maneuver. You raise the nose, reduce back pressure and roll.

What you are describing is a slow roll. There you are doing a roll along a line, and use rudder and forward elevator to maintain staight flight while rolling.
Click to expand...
Good point, I wasn't paying attention.

A quibble, though. An aileron roll is a zero G maneuver. The nose falls through vertical with no lift generated for most of the roll.

A barrel roll is a positive G maneuver.
 
Nope, not zero G. You have weight on your butt throughout the maneuver. Less than 1 G yes, but not zero or negative. You can easily do one in a carburetor engine without the engine quitting.

A slow roll you do hang in the harness.
 
Pinecone said:
Nope, not zero G. You have weight on your butt throughout the maneuver. Less than 1 G yes, but not zero or negative. You can easily do one in a carburetor engine without the engine quitting.

A slow roll you do hang in the harness.
Click to expand...
Yep, zero G, no weight on your butt. Unsecured objects will float in the cabin. Seen it happen several times.
 
Unlike a slow roll which is a judged competition maneuver, there's no formal definition of an aileron roll. Usually you'll unload to almost zero g but not quite, if only to keep fuel in the carburetor and oil in the sump.
 
Stewartb said:
Do tell. Go fly your plane at 30 mph on final. We’ll watch the news for the story.
Click to expand...
indicated, calibrated, equivalent, true, or groundspeed?
Do you think a stall at 30mph (pick your flavor of airspeed) is a result of the airspeed or the angle of attack at which you attain that airspeed?
I can't fly an approach at 30mph calibrated because I'll exceed my wing's critical angle of attack trying to maintain 1g at that airspeed, but I can fly unstalled at 30mph calibrated. You *should* be able to as well, but it's a matter of skill, not aerodynamics.

Nauga,
pushing to make the houses get bigger
 
My Cub flies rock solid at 20 mph. My Cessna? Not so much. In my example it’s aerodynamics, not skill.
 
Stewartb said:
My Cub flies rock solid at 20 mph. My Cessna? Not so much. In my example it’s aerodynamics, not skill.
Click to expand...
In your example you've added constraints such that the critical angle of attack will be exceeded trying to maintain your additional constraints at that low airspeed. In that case stall is *still* a function of angle of attack, with airspeed as a fallout of the condition ("final", i.e. 1g flight) you specified.
A skilled pilot can fly a decelerating climb and push to less than 1g while still decelerating to decelerate below 1g stall speed without stalling.

Nauga,
unloading
 
Tell the OP. I’m not interested in chalkboard aviation as much as useful flying.
 
Stewartb said:
Tell the OP. I’m not interested in chalkboard aviation as much as useful flying.
Click to expand...
"Useful flying" for many seems to include a lot of misconceptions that could be cleared up with a chalkboard.

Nauga,
and stability and control for the hard of hearing
 
brcase said:
I have seen 3 failed engine outs from the pattern at our airport, Plane came up less then 1000 feet short in all 3 cases.
I seen zero stall spin accidents from the pattern.

Brian
Click to expand...

I was told by my instructor that engine outs happen more near an airport because you are changing things to the engine. An hour or 2 at cruise is the same conditions to the engine. Now you are changing air/fuel ratios, prop speeds and power settings when you land. I dont know if thats really true, but it stuck with me.
 
charheep said:
I was told by my instructor that engine outs happen more near an airport because you are changing things to the engine. An hour or 2 at cruise is the same conditions to the engine. Now you are changing air/fuel ratios, prop speeds and power settings when you land. I dont know if thats really true, but it stuck with me.
Click to expand...
1st one 10 miles from the airport climbing away from it.
2nd on a go around
3rd and 4th enroute
5th climbing through 10,000
6th at V1
7th enroute

:dunno:
 
Last edited:
nauga said:
"Useful flying" for many seems to include a lot of misconceptions that could be cleared up with a chalkboard.

Nauga,
and stability and control for the hard of hearing
Click to expand...
Misconceptions are probably miscommunications. In either case a newish pilot like the OP is told to refer to his POH for guidance, and them engineer fellers translated all them fancy chalkboard values into airspeeds so the little people could herd these contraptions around without killing themselves.
 
An aileron roll is 0-1g because the airplane doesn't turn. As the name implies, the airplane rolls throughout the entire maneuver, at no point is it performing a banked turn. You aren't more clever thinking you won an argument just because the other person just said "bank" instead of "banked turn."
 
charheep said:
... I dont know if thats really true, but it stuck with me.
Click to expand...
Pretty sure the guy who told you that doesn't know either, that's how "facts" like that get passed on. No data, no evidence, just sounds good.
 
flyingron said:
Airspeed doesn't cause or prevent stalls.
Click to expand...
A statement that is both true and false at the same time. Absent an angle-of-attack indicator, airspeed is the next best measurement, but requires knowing what causes the relationship between airspeed and AoA to change.
 
sarangan said:
I agree that a constant descent-rate is no different than level flight in terms of load factor and stall speeds. However, the main message on that video is not to pull back on the yoke during the turn. If you let the nose fall and let the airspeed build, then you are less likely to stall. In other words, it is the increase in airspeed and not the suggested reduction in stall speed that is providing the extra safety. Sometimes people have the right concepts but have less precise explanations.
Click to expand...

You really don't even need to let the speed increase if you maintain a nice constant attitude turn at a reasonable approach speed you still won't get close to stall.
C-172 Clean Stall speed = 44 kts.
45 Degree back = 19% increase = 52 kts


Normal approach speed for a 172 is usually about 65kts. so you still have a 12 kt Buffer

A 60 Degree bank = 40% increase = 62kts, putting you right on the edge, but then I challenge you to get your 172 to actually do a drop a wing (spin entry) from a 60 degree bank. I am sure it can be done, but it ain't easy and not something you would likely do inadvertently. Try it at a safe altitude at 50-55 degrees bank some time, preferably with an instructor comfortable with letting you try it. It is similar to the Accerlated Stall maneuver for the Commercial rating, but going to an aerodynamic Stall indication instead of the Stall warning (1st indicated of stall). Note, it will probably be easy to get the stall warning to go off, but the actual stall will likely be difficult.

Brian
CFIIG/ASEL
 
You must log in or register to reply here.
Back
Top