the dreaded base to final turn

[rq3]

You will have to pardon my ignorance. I have not seen the display on a CYA-100. I just wondered what number of degrees most pilots were seeing on your display at the place where they calibrated the stall on the instrument. 

The number of degrees is that at which stall occurs, regardless of bank angle, weight, or density altitude.

 

Rip

[DonMuncy]

Thanks

[rq3]

Thanks

No problem, Don. There's a lot of confusion as to what these devices actually do, and don't do.

Don't hesitate to e-mail me at rquinby@snet.net or call at 203-431-9056.

 

Rip

[Hank]

Don, your flaps do no such thing. A wing with flaps down will stall at a LOWER angle of attack than with flaps up. It will also stall at a lower AIRSPEED, which is what confuses most folks. The wing stalls at ONE angle of attack, and at an infinite number of airspeeds.

A vane, like the CYA-100 (which I make and market) measures TRUE angle of attack. Differential pressure does not, although it may be good enough for government work.

 

Rip

Correct my understanding:

- the wing will stall at the same angle of attack (of the wing)

- lowering flaps changes the chord line of the wing, increasing the angle of attack of the wing

- in our Mooneys, lowering flaps lowers the nose, reducing the apparent angle of attack

- stall still occurs at the same angle of attack of the wing but with the nose-lowering effect of our flaps, the AI will show a reduced angle of nose to the horizon.

What is average CYA install time? Should calibration be included in that, or can I do it (alone) afterwards, or is it a 2-person job (one to fly, one to watch lights and push buttons)?

Thanks, Rip.

[Marauder]

Correct my understanding:

- the wing will stall at the same angle of attack (of the wing)

- lowering flaps changes the chord line of the wing, increasing the angle of attack of the wing

- in our Mooneys, lowering flaps lowers the nose, reducing the apparent angle of attack

- stall still occurs at the same angle of attack of the wing but with the nose-lowering effect of our flaps, the AI will show a reduced angle of nose to the horizon.

What is average CYA install time? Should calibration be included in that, or can I do it (alone) afterwards, or is it a 2-person job (one to fly, one to watch lights and push buttons)?

Thanks, Rip.

Hank - I have the CYA system. I don't have an exact number for installation time since mine was done during the annual. I think my mechanic thought it took around 3 hours for the hardware installation. This does not include the calibration time. You need a couple of people to do this. There is a temporary button attached for the calibration. This is removed afterwards.

[FlyDave]

Rip,

 

Do you have plans to add a heated version of your AOA?. I think icing conditions would be a very handy time/place to have an AOA (in addition to the pattern).

 

Thanks,

 

Dave

[aviatoreb]

Don, don't be embarrassed. Most pilots don't realize that a wing stalls at a LOWER angle of attack with flaps than without.

Even the other Angle of Attack manufacturers have this wrong. And that's why they have their calibration wrong,too.

 

Rip

 

Really?!!!  I never read otherwise, but I always figured that the wings stall at a slightly higher angle of attack with flaps - for two reasons I thought this.  First the flaps are effectively virtually changing the shape of the wing, to a thicker one and one with a deeper camber, and second the stall speed is slower consistent with a higher angle of attack.  I am not doubting you, but can you explain please then especially where my second thought is wrong?

 

Thanks,

Erik

[rq3]

Correct my understanding:

- the wing will stall at the same angle of attack (of the wing)

- lowering flaps changes the chord line of the wing, increasing the angle of attack of the wing

- in our Mooneys, lowering flaps lowers the nose, reducing the apparent angle of attack

- stall still occurs at the same angle of attack of the wing but with the nose-lowering effect of our flaps, the AI will show a reduced angle of nose to the horizon.

What is average CYA install time? Should calibration be included in that, or can I do it (alone) afterwards, or is it a 2-person job (one to fly, one to watch lights and push buttons)?

Thanks, Rip.

Hi Hank;

Remember that angle of attack is defined as the angle bewteen the relative wind and the chord of the airfoil. For a given airfoil, the stall angle is always the same. When you drop flaps, you effectively have a new, thicker airfoil which will stall at a lower angle of attack. Airspeed and pitch angle only enter into this as secondary effects.

 

It's hard to come up with an "average" install time. I've heard stories of as little as 2 hours, but certainly no more than one easy day. Calibration involves pushing a button at Vx or Vy (or whatever airspeed you want to be your minimum angle of attack), and pushing it again just above stall. You could certainly do it yourself, but for safety sake it's best to have a pilot fly and watch for traffic, and the "flight engineer" push the button.

 

Rip

[rq3]

Really?!!!  I never read otherwise, but I always figured that the wings stall at a slightly higher angle of attack with flaps - for two reasons I thought this.  First the flaps are effectively virtually changing the shape of the wing, to a thicker one and one with a deeper camber, and second the stall speed is slower consistent with a higher angle of attack.  I am not doubting you, but can you explain please then especially where my second thought is wrong?

 

Thanks,

Erik

Hi Erik;

It is counter-intuitive, isn't it!? The best thing to do is look at the lift/drag plots for a given airfoil. A given airfoil will stall at a lower angle of attack with flaps deployed. Because the lift coefficient is greater with flaps, you can fly at a lower airspeed for the same required lift, but the angle of attack will be lower at stall.

 

Rip

[rq3]

Rip,

 

Do you have plans to add a heated version of your AOA?. I think icing conditions would be a very handy time/place to have an AOA (in addition to the pattern).

 

Thanks,

 

Dave

No plans for heat, and here's why. If you calibrate for a clean wing, and then get ice, you become a test pilot. You have no idea what the stall angle of attack will be. Heating the vane would imply that you could rely on it during an ice encounter. You can't, and my own opinion is that implying otherwise is dangerous.

 

Rip

[PTK]

How will starring at yet another thing in the panel help salvage an overshot final?

How will it help the doomed pilot who allowed a stall spin to develop by incorrectly introducing yaw?

Which is more dangerous: a steep coordinated turn close to the ground or a yawing turn?

How does it help a pilot in nose dropping and bank increasing dilemma?

Just curious. An AOA indicator may be of some help elsewhere but here?

Get an AOA gadget if you will, but put some money in some training as well. Learn to plan for and fly the conditions.

These accidents are best prevented with a healthy understanding of the dangers involved.

Just my opinion!

[Bob - S50]

The best AOA gauge I ever used was in the T-38.  What I liked about it was that it was not only calibrated for stall, but for Max range, 99% of max range, and max endurance AOA.

 

If I ever get an AOA, I'll want one that shows all those AOA's as well, not just stall.

 

Bob

[rq3]

How will starring at yet another thing in the panel help salvage an overshot final?

How will it help the doomed pilot who allowed a stall spin to develop by incorrectly introducing yaw?

Which is more dangerous: a steep coordinated turn close to the ground or a yawing turn?

How does it help a pilot in nose dropping and bank increasing dilemma?

Just curious. An AOA indicator may be of some help elsewhere but here?

Get an AOA gadget if you will, but put some money in some training as well. Learn to plan for and fly the conditions.

These accidents are best prevented with a healthy understanding of the dangers involved.

Just my opinion!

 

One of my Mooney customers claimed that 6% of Mooney accidents were turn to final stall/spin, while 20% (!!!) were loss of control on the runway after landing. His thought was that carrying too much speed on final was the primary contributing factor. An angle of attack indicator automatically corrects for weight, bank angle, and density altitude so you can nail a safe and reasonable approach every time, with no "fudge factor" (if 80 knots is OK, 85 is just a bit better).

 

I've never confirmed his numbers, but based on my admittedly limited Mooney time they make sense.

 

Rip

[Andy95W]

An angle of attack indicator automatically corrects for weight, bank angle, and density altitude so you can nail a safe and reasonable approach every time, with no "fudge factor" (if 80 knots is OK, 85 is just a bit better).

Yes, but good recurrent training does the same thing and costs less.

[rq3]

Yes, but good recurrent training does the same thing and costs less.

 

Recurrent training automatically determines the optimum approach, in real time, taking into account weight, bank angle, and density altitude? And how much training do you get for $625?

 

Don't get me wrong, I'm all for recurrent training. IMHO the vast majority of pilots don't get enough. But an angle of attack indicator tells you, directly, the ONE thing you must know about your wing. No other device does the same thing. We've all been taught to rely on second order information, like airspeed.

An AoA indicator is a tool, like any other instrument. It can be mis-used. I also believe it can save lives, and urge everyone to get one, even if it's not one of mine!

I'd also like to address the idea that there is an "AoA bandwagon". If there is, it's only because it wasn't until recently that the confluence of technologies became available to make these things simple, reliable, and affordable. I looked at designing a unit back in the late 70's. It wasn't reasonable back then.

[aviatoreb]

Hi Erik;

It is counter-intuitive, isn't it!? The best thing to do is look at the lift/drag plots for a given airfoil. A given airfoil will stall at a lower angle of attack with flaps deployed. Because the lift coefficient is greater with flaps, you can fly at a lower airspeed for the same required lift, but the angle of attack will be lower at stall.

 

Rip

 

Hi Rip, It is counterintuitive - and now I am understanding exactly the reason you are saying.  I didn't guess it correctly. 

 

By the way, I got the alpha systems a couple of years ago - almost immediately after the FAA started allowing us.  I have AoA and I would say to anyone get it!!!  My landings definitely improved - and consistently so - and I shook that neurotic desire you stated properly - fear of slow in that if 80 is good then 85 must be better.  That in itself leads to accidents.

 

One thing I really like about my alpha systems is that it speaks to me in English if I exceed some specified angle of attach - I want it to catch my attention if I ever have a bad day and let my speed decay and I am not even looking at my AoA instrument.  Have you ever thought of a voice annuciation of exceeding a critical threshold (a bit before stall AoA to give ample warning).  Mine says "getting slow".  Which is very reasuring to hear if I am just starting the flair - and I am sure it would wake me up if I were in the middle of a base to final turn or an instrument approach sequence I hope.

[aviatoreb]

Yes, but good recurrent training does the same thing and costs less.

 

I hear this stated so often to any discussion of good aeronautical discussions.  Can't we have both?  Good training and good instruments?  I want both.

 

By the way - I would say that recurrent training is MORE expensive than this inexensive AoA over time - but that is imaterial to me since a) I got the significantly more expensive alpha systems (as I said it was all that was available at the time and also I do like that it is heated and voice annunciations), and I am recurrent training AND flying my AoA.  In fact, I did so much recurrent training I did a commercial checkride just last week - and the DPE was very impressed with my AoA - he said so.  It was a lot of fun for the accelerated stalls especially (roll into 45 degrees then start pulling until you stall coordinated WITH ball centered - then recover - still coordinated) - very reasuring to do it with an AoA device and even a voice declaring the precursor onset of stall ... an accelerated stall at near Va.  It felt like cheating on a test with lift reserve indication.

[PTK]

Rip, the op and the discussion is on the base to final turn.

What does an AOA gadget tell you about your wings in a stall spin?

Specifically about the already stalled and dropping inside wing in an uncoordinated and yawed condition as the airplane enters the deadly spin?

[rq3]

Hi Rip, It is counterintuitive - and now I am understanding exactly the reason you are saying.  I didn't guess it correctly. 

 

By the way, I got the alpha systems a couple of years ago - almost immediately after the FAA started allowing us.  I have AoA and I would say to anyone get it!!!  My landings definitely improved - and consistently so - and I shook that neurotic desire you stated properly - fear of slow in that if 80 is good then 85 must be better.  That in itself leads to accidents.

 

One thing I really like about my alpha systems is that it speaks to me in English if I exceed some specified angle of attach - I want it to catch my attention if I ever have a bad day and let my speed decay and I am not even looking at my AoA instrument.  Have you ever thought of a voice annuciation of exceeding a critical threshold (a bit before stall AoA to give ample warning).  Mine says "getting slow".  Which is very reasuring to hear if I am just starting the flair - and I am sure it would wake me up if I were in the middle of a base to final turn or an instrument approach sequence I hope.

 

I did consider voice alerts. There's an old military study out there that determined pilots will respond more quickly to a tone than to a voice. You have to hear, interpret, and act upon a voice command. A trained pilot will react to a unique tone like Pavlov's dogs. Plus, voice is expensive. I wanted the CYA-100 to be as simple and inexpensive as possible. Do one thing, and do it well. I wanted the price to be about one fill-up of avgas for my Navion. I wish I could price track avgas prices, but electronics manufacturing doesn't follow the price of crude, and my distributor takes their cut, too.

[rq3]

Rip, the op and the discussion is on the base to final turn.

What does an AOA gadget tell you about your wings in a stall spin?

Specifically about the already stalled and dropping inside wing in an uncoordinated and yawed condition as the airplane enters the deadly spin?

 

In a spin, by definition, the wing has stalled. The AoA gadget will show that (or at least should. I know mine does). The idea is to never get there. I've had a few aerobatic pilots ask me if they could install two, one for inverted flight. It would work, but the "prototype" Pitts isn't flying yet.

[Hank]

Rip, the op and the discussion is on the base to final turn.

What does an AOA gadget tell you about your wings in a stall spin?

Specifically about the already stalled and dropping inside wing in an uncoordinated and yawed condition as the airplane enters the deadly spin?

If you're stalled and spinning in the base to final turn, NOTHING will help, and you've no time left to learn anything.

The AoA, properly used, will keep you from stalling by telling you exactly how much slower you can safely fly. Right now, we all estimate this, but the AoA is not an estimate, it's a direct measurement. You still have to keep the ball centered, though.

Why are you so against having an accurate measurement instead of using a rule of thumb, augmented by a guess?

[aviatoreb]

I did consider voice alerts. There's an old military study out there that determined pilots will respond more quickly to a tone than to a voice. You have to hear, interpret, and act upon a voice command. A trained pilot will react to a unique tone like Pavlov's dogs. Plus, voice is expensive. I wanted the CYA-100 to be as simple and inexpensive as possible. Do one thing, and do it well. I wanted the price to be about one fill-up of avgas for my Navion. I wish I could price track avgas prices, but electronics manufacturing doesn't follow the price of crude, and my distributor takes their cut, too.

 

Ah - so you do have an audible warning too?  Some kind of unique tone?  So long as you have something to catch pilots attention even they do not happen to be looking at the instrument, then super. In that cause I would have been awfully stuck as to what to choose if yours had been available a few years ago when I did the install.  Sounds like a superb product and price - I love the simple design.  Better mouse trap for sure.

[rq3]

Ah - so you do have an audible warning too?  Some kind of unique tone?  So long as you have something to catch pilots attention even they do not happen to be looking at the instrument, then super. In that cause I would have been awfully stuck as to what to choose if yours had been available a few years ago when I did the install.  Sounds like a superb product and price - I love the simple design.  Better mouse trap for sure.

 

Oh, yes indeed. After deciding on a tone rather than voice, I polled all of the pilots I know which tone they found the LEAST like what was already in their planes (stall, gear, etc.), and the MOST likely to get their attention immediately. The result is the aggravating, warbling, high pitched tone in the CYA-100. I'm pushing "old age", and have high frequency loss in my left ear, but it even pisses me off. I just gotta push the stick to escape it ;-)

[alex]

Do you have any pictures of an installation on a mooney by chance?

[jlunseth]

Bob, I am trying to respond to your post on P. 3 of this thread and can't get my system to copy it.  But here are my thoughts, for what they are worth. 

 

"Bank angle in itself will not cause a stall."  I think what you mean to say is that if you increase bank, let's say from level to 60 degrees, and let the nose fall as it wishes, there will not be a stall.  That would be true to a point, but bank angle in itself does cause a stall.  If you are in level flight in my aircraft at say, 75 kts., and you quickly bank to 60 and the aircraft remains in level flight (no descent), the aircraft will stall immediately.  That is how accelerated stalls are done.  It is true that if you let the nose fall, you may be able to stay out of a stall, but my experience with steep spirals tells me that even nose down and descending you can stall at 60 degrees.  We don't have any numbers to go by to know if a 750 fpm descent rate will keep us out of the nose down stall where a 500 fpm rate will not, in others words unloading the wing can prevent the stall but we have no way of knowing how much to unload except what the stall horn is telling us. This stall will happen whether you stay coordinated or not.  Accelerated stalls also tend to be more rapid and require a quicker response to prevent a spin. 

 

On another issue I see raised in the thread, quite a lot of us fly the pattern at 90 downwind, 80 or 85 base, and then 75 or 80 on final.  That base to final turn is going to be in the 80-85 kts. range.  Obviously, there are a lot of different Mooney types and some want more speed than others, thus the range.  That is less than the level flight, flaps extended, 60 degree bank stall speed of my aircraft, and all of our aircraft that I am aware of.  It is true that if you are nose down you can mitigate the issue some, but from experience you need to be aggressively nose down not just a little nose down, and at that point in your descent you are probably 400 AGL, so aggressive nose down is really not an option.  My point is that 60 degrees of bank in a base to final turn in our aircraft, coordinated or not and nose down or not, will generally not end well.  Honestly, I think Mooney pilots need to think in terms of a maximum of 45 degrees in that turn, and even that would be a "performance" turn, 30 is a lot safer.

 

Keep your patterns big and use no more than 30 degree turns.  We would all much rather that everyone do that and then come back and argue LOP/ROP with us here in this forum,  than the alternative.