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Lost a Mooney pilot today


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49 minutes ago, Andy95W said:

Sorry, Anthony, .....  (edited for making this point...)

Put another way: if you are in a 60° bank with the nose of the airplane 15° below the horizon at 72 knots, you won't be anywhere close to the critical angle of attack and therefore you won't stall- but you will be descending like crazy.

But I absolutely agree that a 45° bank at 72 knots on base is a pretty stupid thing for all of us who aren't Bob Hoover.

Andy,

I tried to include a few safeties that people use to increase the margin of safety, including lowering the nose /AOAi...

It took me a few attempts to edit my post, in real time... You may have seen an early version...  :)

One thing I am looking for, because it isn’t in the POH... 

Is there a rule of thumb on how much unweighting one gets per degree nose down attitude?  (Ideal, no accelerations,

What would be the effect of x degrees nose down attitude on stall speed?  I highlighted the part of interest in your post.

Or am I just aiming to join 201er and others in the Pro AOAi line?

 

Thanks for your input. I greatly appreciate it.

Best regards,

-a-

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All I know is we took a short flight today and had some tricky cross winds to deal with and as I was flying the approach on the different stages of the pattern all of these post and the ones on spinning the Mooney were buzzing through my head. I had to shake it off and fly the dam airplane. But this stuff is very good to read and let soak into your mental tissue. 

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3 hours ago, Andy95W said:

Sorry, Anthony, this is only true when attempting to maintain level flight, which probably is not the case in the traffic pattern.

Everybody knows that "a wing can stall at any speed", it stalls when it exceeds its critical angle of attack.  In exactly the same vein, "a wing may not stall at any speed", unless it exceeds its critical angle of attack.

Put another way: if you are in a 60° bank with the nose of the airplane 15° below the horizon at 72 knots, you won't be anywhere close to the critical angle of attack and therefore you won't stall- but you will be descending like crazy.

Be a little careful about that--the wing is "unloaded" (or the AOA is decreased) when nose is dropping, or more specifically, when the plane is accelerating downwards.  However, if you are holding the nose low at a constant pitch, the wing loading is the same as that for a level turn.

For example, when you bank 60 degrees, and then let the nose drop, those first few moments you are unloading the wing less than 2g.  However, if you then hold the nose at, say, 15 degrees down, your wing loading goes back up to 2g.  If you then pull the nose back up to level, the loading goes higher than 2g, and then back to 2g when you keep the nose level.

In other words, descending only helps unload the wing for the first few moments when you drop the nose.  Once you stop the nose dropping, your wing loading jumps back to the same for level flight, even if you're still nose low.  

Or maybe another way of saying the same thing is your pitch attitude does NOT change your wing loading. Only the moments when your pitch attitude is CHANGING does your wing loading change.

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^^^^  Which is what I think is getting people who fly a box pattern.  You are doing turns, unloading and loading the wing.  Pointing up and pointing down loading and unloading the wing.  Meanwhile worrying about being to fast and floating.

The U turn to land with energy decreasing is much more smooth and keeping forces more equal all the way through the turn to the landing.

 

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I typically fly the base as a continuos turn with a constant descent. And if I'm doing a down wind departure I do the same for the crosswind to downwind. Just seems easier and makes it so I am able to fly a small pattern without needing to go more than 15 to 20 degrees bank.

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8 hours ago, jaylw314 said:

 

In other words, descending only helps unload the wing for the first few moments when you drop the nose.  Once you stop the nose dropping, your wing loading jumps back to the same for level flight, even if you're still nose low.  

 

Yes, I agree with your entire post, especially the above statement- particularly my bold highlight.  Changing the pitch attitude changes the AoA to the relative wind regardless of pitch attitude to the horizon, just like you said.  Thank you for helping clarify.

My extreme of 15° nose down, in our aircraft, will quickly increase the speed to well over the 72 knots that Anthony used in his example.  So the point is basically moot unless you started the maneuver at an even more extreme 20° nose down.  But yes, the wing can stall (or not) in any attitude, at any speed, because it's all about Angle of Attack and relative wind- which is the point I made (or tried to make) in my post.

Since we're talking about a Mooney and not an Extra 300, I'm going to stop splitting hairs and let everyone get back to the more pleasant discussion of bank angles and airspeeds in the traffic pattern.  I personally use 90/80/70 and limit myself to 30° of bank or I go around and try again.

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It is pretty easy to cause an aircraft to stall in a mild nose down attitude and in a descent.  Just reduce the airspeed enough.

Here is some real life.  When I was practicing for my commercial I found I could get a Stall, Stall! alert in a “Steep Spiral” maneuver, that’s nose down and descending in a bank that varies, at 81 knots, clean configuration.  The landing configuration 0 bank stall speed in my aircraft is 51-57 (it varies depending on CG).  I certainly wasn’t doing 60 degrees in those steep spirals, maybe 45 at times.  So how is that possible?  The performance we are all used to in our aircraft is power on performance.  In power on performance the prop wash is creating lift.  Steep spirals, where I found this high stall speed (or pre-stall, the horn goes off before incipient stall) is done with the engine idling and no prop wash lift.  You are a glider. And it happened more than once.  Variable winds are another real life factor.  I have seen instantaneous airspeed changes of as much as 10 kts.  If you are low and powered down, that gets your attention.  

The pattern, powered down and banking, and often moving through mild wind shear approaching the surface, is not the place to test the knife edge of theory, because theory and real life are not the same.  

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So JL..,

Why is the spiral flown at 81kias?

Sounds like a really busy time to find yourself on the edge of a stall.

I’m not familiar with the commercial requirements...

Having minimum energy during the time when your are throwing away as much energy as possible... sounds like paying attention to the pennies while throwing the more important dollars around...

if it’s a discussion regarding performance... performing a spiral @90kias would be a tad safer...

Best regards,

-a-

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Best glide, which varies a little with CG.  Its 81-85 in my aircraft, just going from memory.  In the steep spiral you are powered down, circling the airport and attempting to maintain approximately the same distance from a point on the airport all around the circle, so bank changes depending on wind direction and where you are in the circle.  The couple of times I found this stall speed, it happened just starting the turn into the wind where airspeed has fallen a little going with the wind, and then bank angle needs to steepen.  You just put the nose down and get faster to fix it, and the alert precedes a stall by about ten kts., but that is what I am saying.  Powered down, descending, and banking, as you are in the pattern, you don’t have alot of cushion above stall.  

When I make my turn crosswind to base, which is similar to that spiral, I watch airspeed like a hawk and put in throttle right away if it is falling below 85, which it tends to do.  I always find myself leveling off a little during that leg, which is the cause of the airspeed drop.  Better to be powered up some at that point.

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8 hours ago, jlunseth said:

It is pretty easy to cause an aircraft to stall in a mild nose down attitude and in a descent.  Just reduce the airspeed enough.

Here is some real life.  When I was practicing for my commercial I found I could get a Stall, Stall! alert in a “Steep Spiral” maneuver, that’s nose down and descending in a bank that varies, at 81 knots, clean configuration.  The landing configuration 0 bank stall speed in my aircraft is 51-57 (it varies depending on CG).  I certainly wasn’t doing 60 degrees in those steep spirals, maybe 45 at times.  So how is that possible?  The performance we are all used to in our aircraft is power on performance.  In power on performance the prop wash is creating lift.  Steep spirals, where I found this high stall speed (or pre-stall, the horn goes off before incipient stall) is done with the engine idling and no prop wash lift.  You are a glider. And it happened more than once.  Variable winds are another real life factor.  I have seen instantaneous airspeed changes of as much as 10 kts.  If you are low and powered down, that gets your attention.  

The pattern, powered down and banking, and often moving through mild wind shear approaching the surface, is not the place to test the knife edge of theory, because theory and real life are not the same.  

Like Anthony, I'm curious about the slow speed used in the Spiral. Why so so slow? The only steep spirals I've done were in cruise configuration for a really rapid descent.

I really agree with your last statement:  theory and practice are the same, according to theory.

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Thanks, @jlunseth. Just two questions left:

  1. My Best Glide is 105 mph, or 91 knots. Your K is significantly heavier than my C, I'm quite surprised your Best Glide is slower . . .
  2. What is the reason for doing the maneuver so slowly? Sure, simulated engine out should be for max distance, but if you are circling the airport, descending to land, it seems to me you'd want to vary the descent to reach the runway facing into the wind. Because when stuff hits the fan for real, I want a real buffer between what I'm doing and a stall/spin . . . .
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Thanks to JL for the additional insight.... !

I did some more reading of my POH...

 

Best glide can be found in section IV... E-Procures....

For the LB....

80kias on the light end...

91.5kias on the heavy end...

Very similar to Best climb speeds...

 

This gives me everything I ever needed to get a G500TXi..... calling my Finance Administrator!  :)

How else would I read 0.5 kias on an analog ASI?

Stall speed in a 45° bank.... 79kias (@max gross)

So....

The Best glide and stall speeds in the bank are going to be very close together...

balancing staying close to the airport and best glide...

stall speeds vary by weight in a similar way as does the best glide speed... a range of about 10kias... from light to heavy...

Best regards,

-a-

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The PTS required maneuver is different from what you might do in a real emergency. You are required to do three turns (or at least that was the requirement at the time, it may have changed).  You are required to chose an altitude to start with and end up at an altitude above the airport +/- which I don’t recall.  But the point is that you are not simply trying to get down fast as you might be if you have an emergency in cruise.  So the best way to do it, at least the way I did it, is to maintain best glide during the circles.  The idea is to give you a number for your aircraft for loss of altitude for one circle, so if you find yourself say 4,500 above an airport how many circles are you going to need to do to wind up at the approach end of the runway at the altitude from which you will land.  

My number at best glide is 1,500.  If you do a true descent from cruise in order to get down from, say, 19k, to the airport, you certainly might want to do it differently to lose altitude as quickly as possible.

One issue is how much altitude you need for three circles.  At best glide in my aircraft that’s 4,500 so you need to climb to about 6,000 to do the exercise.  Remember it is a bust if you don’t make three circles, and it is also a bust if you wind up at an altitude that is not safe, or certainly that is lower than what is in the regs. for the area you are over.  The other issue in my aircraft is that unless you do the maneuver in the dead of summer, the engine cools below levels where you can just apply whatever power you want at the end of the maneuver, you are restricted by the POH in the MP that can be applied until the engine warms over 250 CHT and 100 dF oil temp, so it was necessary to leave a little bit of a cushion for that also.  You can certainly descend faster, but you have to go higher to do that.  That means wasting time in the practice area climbing to 10 or 12 or whatever you need to go to, to permit a faster rate of descent.

Best glide circles are how I did it, it was simplest and reduced the climb to altitude.

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On 9/10/2018 at 9:46 PM, steingar said:

I think once my airplane is returned to me from the avionics shop from hell I will fly wider landing patterns. Normally I fly within easy gliding distance to the runway, but I find myself exhibiting poor airmanship, banking at steeper angles at lower speed than I find comfortable.  Truth be told the aircraft shed energy far more slowly than the trainers I’ve flown in the past, and I think the extra room will give me time to effect more stabilized approaches. I’m certain a better pilot could easily do it within gliding distance of the airport, but we all have to be who we are.

Normally one doesn’t want to do this in case the engine quits in the landing pattern. But given proper fuel management, this sort of scenario is vanishingly rare. What isn’t rare are stall spin accidents within the landing pattern.

Agree.  With all of these stall-spin crashes in the pattern, I think it’s time to eliminate “nice, tight pattern” from the standard repitoire.  Obviously there are exceptions, but given the choice, I’ll take the lesser risk of coming up short if the engine quits vs stall-spin.  I personally know someone who lost their engine on final and came up short. He broke some teeth and had some bruises but was fine other than that.  I don’t know anyone who has survived the other although I’m sure there one or two lucky ducks. 

Just my opinion. 

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Just FYI, "easy gliding distance" to the airport is not necessarily what you think.  Going back again to the exercises I did to get my commercial, I found that if I was at pattern altitude and a half mile or less from the airport, it was very difficult to make the runway unless there was a strong crosswind blowing you away from the runway.  The reason is that you either have to make a very steep banking turn to avoid blowing through final, which causes too much loss of altitude and puts you in a very precarious no power steep bank, or you have to make a 270 rather than a 180 because you wind up blowing through the final approach course and have to continue with the turn to try to get to the runway.  The steep banking turn also produced too much drop, and with no engine to help, just the airframe, it is difficult to arrest that drop enough to make anything but a very hard landing.  The commercial maneuver is the Power Off 180, and it is a bust if you use the engine.  It would also be a "bust" in real life, if you have no engine to use.  The magic number was 3/4 mile to a mile.  3/4 is better if the runway is upwind of the side of the pattern you are on.  That is for my airframe, I don't know what a different airframe would do.  I would guess that the F's and older might be able to use a tighter pattern, and the long bodies might need even more room, but I have not tried the maneuver with either of them, but that is just a guess.  The best thing is to get with a good instructor and figure it out. 

But I don't know why we even worry about that.  So you have flown, say, from Minnesota to Colorado, and the engine did not quit during full power takeoff and climb, and then it did not quit for 4 hours or so at cruise, and now we are afraid it is going to quit during low power ops in the pattern, especially where a good deal of the work is going to be in a descent where power is near idle and the airspeed helps drive the prop?  It makes no sense to me, given that this is one of the  areas that produces the highest accident rate and a high percentage are fatal.

Edited by jlunseth
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