Bank angle wing loading data??

Does anyone know where to find data for the 9a
Or any model for that matter of bank angle load factor?

For example, Vans Data 9a: at Gross weight 1750 lbs (160 hp)
Stall speed is 50 mph. What would the stall speed be with
a 45 deg bank? 60 deg?

Does this data need to be computed by each individual
POH?

The bottom line: when I am at a base to final turn, or any turn, I don't want to
guess at my airspeeds weight dependant to keep from stalling.

agirard7a said:

Does anyone know where to find data for the 9a
Or any model for that matter of bank angle load factor?

For example, Vans Data 9a: at Gross weight 1750 lbs (160 hp)
Stall speed is 50 mph. What would the stall speed be with
a 45 deg bank? 60 deg?

Does this data need to be computed by each individual
POH?

The bottom line: when I am at a base to final turn, or any turn, I don't want to
guess at my airspeeds weight dependant to keep from stalling.

Click to expand...

The traditional bank angle vs. load factor graphs/calculations will only be valid for a level turn at that bank angle.

For example, I can go out and pull 6g with wings level (at least until I run out of airspeed) and I can do 1g with 80 degrees of bank (though I will run up to redline very, very quickly). If I'm trying to bring the nose up while banked, that implies a higher g load than a level turn.

That said:

For level turns, load factor = 1 / cos (bank angle)



15deg bank = 1.04g
30deg bank = 1.15g
45deg bank = 1.41g
60deg bank = 2g
75deg bank = 3.87g

or restated:
1.5g = 48deg
2g = 60deg
3g = 70.5deg
4g = 75.5deg
5g = 78.5deg
6g = 80.4deg



Now, we have to relate that to stall speed.

Lift = 1/2 * (density) * (velocity^2) *(wing area) * (Cl)

Since we're concerned about relative stall speeds only, we can ignore the density, and wing area and CL are constant.

Now, if we pull 2g's, that means the airplane needs to generate twice as much lift; since all the other factors are assumed constant, (velocity^2) needs to double, too. So, stall speed at load factor X = square root (x) * 1g stall speed.

Stall speed factors:
2g = 1.41 * original stall
3g = 1.73
4g = 2
5g = 2.24
6g = 2.45

If your airspeed indication is truly calibrated and accurate for all AOA ranges, you could compute it from this formula. But it's possible that airspeeds can indicate lower due to installation differences, and relying on these calculations could give erroneously low airspeeds for stalls at high load factors.



In my humble opinion, worrying about trying to compute a constantly-varying stall speed for a given bank angle and G load while you're trying to fly the airplane is an attention hog. It would be far better to fit an AOA indicator (and even better, one with an audible tone) that shows how close you are to stall regardless of airspeed or load factor.

Solution

Ok. I called Vans about this. This data does
not exist from their knowledge. Maybe someone
has done it with extensive flight testing.

Solution: install an AOA! Computed for
5 mph above stall speed.

Sounds like a plan and a life saver.

Computation

Bob. Thanks! That was the info I was looking for to at
least try to quantify rather than guess or assume.

With your formula: ( if i am correct) with a 48 deg bank, stall
Speed is increased 1.5 x 50mph ( stall for 9a
At gross 1750) = 75 mph stall speed.

Interesting! Being that most people seem to
Recommend pattern speed in the 9 at 70 mph,
That better not be at or near gross weight or near
48 deg of bank! Obviously 80 mph at gross is a safer bet
And a go around if you overshoot the base to final!

I wonder how many people have died making this mistake?

When you're descending in a turn with the wing "unloaded" the stall speed is going to remain pretty low even with a steep bank angle.

How over the top "numbers slave" you want to go? That will dictate the answer, but at the end of the day approximations are close enough for human based flight ops Engineering data will vary depending on the aircraft specific configuration and particulars - airframe flex, planform particulars, aerodynamic twist under load, etc. But for general rules of thumb, Post 2 spells it out. Wing loading affects stall speed - you can determine *approximate* stall speed delta per unit bank angle quite easily.

The reason Van's Does not have the data for the 9A is because it is a generic question and the base line equation remains the same for the 9A or the B-747-8I when you are talking about rules of thumb and figures decent enough to give accurate situation awareness.

For example, a 30 degree bank angle, typical pattern maneuvering, your G loading is 1.15 and stall speed is 1.07*Vso. So you have an adequate maneuvering margin with pedestrian bank angles to be at final approach speed though it is obviously reduced somewhat while maneuvering compared to wings level. That's why it is common practice to delay reducing that final 5-10 kts (to final approach speed) only once aligned with the runway, wings level.

For a stall speed of 50KTS in smooth air and in coordinated flight:

30 Deg Bank ~ Vso*1.07 = Stall appx 54kts
45 Deg Bank ~ Vso*1.19 = Stall appx 60kts
60 Deg Bank ~ Vso*1.41 = Stall appx 71kts
75 Deg Bank ~ Vso*2.00 = Stall appx 100kts

PS a wing won't stall at 0 G. But you will be arcing to tierra firma pretty quickly none the less.

Landing configurations are going to be limited in G capability in many designs and also there may not be a stall speed below limiting flap speed in some bank angles nor would anyone want to be normally maneuvering in some configurations at 75 degrees bank for example. Therefore it's a good idea to also do some figuring with clean wing stall speed and add a margin for "turbulence", "uncoordinated flight", "pilot control technique" and other complications that may also increase stall speed if you want to get a good feel of what to expect. Then experience in the airframe will give you a seat of the pants feel and some level of innate situation awareness.

Simply saying "who cares, install an AOA indicator" is not good enough, it's too reactive. To be proactive and occupy the seat with enough SA to fly safely, we all still need a good handle on what to expect with various bank angles. An AOA gauge is a great tool as long as it's not a crutch. (Edit - Paul is right a few posts from here, my original statement on a "crutch" applies only if we use a tool without the knowledge of how a tool works and don't know how to anticipate it's best use)

Expanded article that covers some of this:
http://www.experimentalaircraft.info/flight-planning/aircraft-stall-speed-1.php

The same data as above for a constant altitude banked turn stall speed.

It may be easier to see in graphical form in the right hand chart -

agirard7a said:

Interesting! Being that most people seem to
Recommend pattern speed in the 9 at 70 mph,
That better not be at or near gross weight or near
48 deg of bank! Obviously 80 mph at gross is a safer bet
And a go around if you overshoot the base to final!

I wonder how many people have died making this mistake?

Click to expand...

Lots of people have died making this mistake, normally they know much better in a 1G day on the ground, but it's during the "impossible turn" after an engine failure where many factors may contribute to stalling and spinning.

Also, you numbers are a bit off. The way I see it (see the link I posted for an expanded mathematical breakdown) you will stall about close to the figures listed in my post. (we are all posting at about the same time, sorry for the redundancy). Keep in mind your clean wing stall speed will be higher, and any uncoordinated flight or turbulence will also factor in to a higher stall speed. This is not to scare you into flying too fast, there are hazards with that too. Just good situation awareness is all that is required and then plenty of stick time feeling the envelope of the aircraft in real life at a safe altitude and with a good aerobatic/spin CFI if possible.

Airspeed

Neal. Assuming in the decent you are gaining
Airspeed. However, in landing configuration, approach
Speeds are wanting to be constant so although descending,
Airspeed remains the same so the stall factor would remain
a constant. I would agree with you with a banked turn in the open sky where speed would naturally increase in decent. Greater airspeed
reduces stall.

Please corrected if I am wrong but decent angle
Should be irrelevant if you are maintaining constant
Speed.

Sorry Eddie, but the AoA is no more a crutch than the Airspeed indicator and a bunch of mental gymnastics to recalculate the current stall speed given the flight path, bank angle, gusts, etc, etc. The AoA does all of that compensation for you.

Ideally, we'd all be superior pilots who simply feel the airplane in the seat of our pants and never accidentally stall becasue we are one with the machine. That hasn't worked too well for a lot of dead folks over the last century.

If you want a reliable indicator of where the airplane is relative to the stall under all flight conditions, and you want that to be somethign other than your hind-quarters, AoA is the far superior instrument.

Paul, sorry, it was not a strong statement of intent, it probably came off the keyboard a little harsh and a bit un-intended. I like AOA, love it in fact, and use it all the time in my professional flying. However, I have heard a few guys mention a few things while hangar flying giving me the impression there are some guys that might not full understand how G loading works. That could be a problem in terms of how they might better be able to proactively manage their flight profiles. That's a training issue. I should have been a better word smith about how I stated that.

So AOA is good, we all can agree on that!

Neal@F14 said:

When you're descending in a turn with the wing "unloaded" the stall speed is going to remain pretty low even with a steep bank angle.

Click to expand...

Absolutely. There are so many variables that the OP might just as well ask "?how high is up?" A level turn is pretty easy to calculate, but this is a descending turn - and the vertical component is a HUGE discriminator in stall speed.

This has been discussed countless times here and always with the same result: A bunch of people take the ?AoA/fly the numbers? tack, while the rest go with ?practice/learn to fly?.

I predict this one is going to go the same way.

agirard7a said:

Please corrected if I am wrong but decent angle
Should be irrelevant if you are maintaining constant
Speed.

Click to expand...

You are right, if you are turning, you are NOT unloaded. Completely unloaded flight means ballistic, 0G flight like in an aggressive stall recovery or some random part of an aerobatic maneuver. Partially (relative) unloaded flight would be during some transition to a higher descent rate or reducing bank angle. You can see this with an AOA gauge while maneuvering. While we load and unload a little here and there during normal maneuvering, we are not (normally) in a constant state of unloaded flight in the pattern. A constant 600 FPM descent, stabilized approach with a 30 degree bank while turning to final is still 1.15G in the pants during that bank and turn and will still give you a 1.07*Vso stall speed until you are wings level where you go back to just Vso.

http://www.experimentalaircraft.info/flight-planning/aircraft-stall-speed-1.php

PS - how high is up? That's relative

Dan Rogers has a pretty good explanation on his acro website, including V-g stall graphs and formulas http://flyacro.us/SpinTraining.html

agirard7a said:

Please corrected if I am wrong but decent angle should be irrelevant if you are maintaining constant speed.

Click to expand...

Correct, climbing or descending is irrelevant if you are maintaining a constant speed. If you are turning at a 45 degree bank with constant airspeed, your G-loading will be the same whether you are climbing, descending, or maintaining altitude. For those who say a descending turn is less loaded than a level turn, that assumes you are allowing the airspeed to increase.

Toobuilder said:

This has been discussed countless times here and always with the same result: A bunch of people take the ?AoA/fly the numbers? tack, while the rest go with ?practice/learn to fly?.

I predict this one is going to go the same way.

Click to expand...

Best summation so far. We will have truly turned a corner when all those flying farmer guys put AOA in their J-3's.

Toobuilder said:

This has been discussed countless times here and always with the same result: A bunch of people take the ?AoA/fly the numbers? tack, while the rest go with ?practice/learn to fly?.

Click to expand...

I'd argue that the two aren't mutually exclusive. Having an AOA indicator within line of sight (or better yet, something like a HUD display with flight path vector vs. boresight) would make learning the relationship between AOA, speed, maneuvering, and performance a much faster process. These kinds of displays give a much clearer picture of what the airplane is actually doing, and once pilots know that, it's easier to correlate cues from their other senses. You could then remove the visual display if you want--though I'd personally see no reason to except for training.


To use a bit of a simplified analogy for my see-then-feel vs. feel-to-see approach, imagine trying to learn how to buck rivets blindfolded, or learn your way around a room you have never been in before with the lights off. It's going to be a long and frustrating process, and wou will likely be drilling lots of rivets out or nursing sore shins.

Now, compare that to trying to do the same with the added benefit of visuals. Learning to buck rivets while you can see the bucking bar and the rivets is much easier; once you get used to doing it within sight it's easier to do it sight unseen. I'll bet 99% of us first learned to buck rivets we could see before moving on to the ones we couldn't. Similarly, even a few seconds' glance at a new room before turning the light out will help us navigate it much better, since we now have a mental map of the room and its major features on which we can place ourselves.

Numbers

Eddie. My numbers where wrong and really
appreciate your input on this. I plan to put an
AOA in my plane. Most importantly however is having the knoweldge and understanding of these critical underlying factors.
Thanks.

luddite42 said:

Correct, climbing or descending is irrelevant if you are maintaining a constant speed. If you are turning at a 45 degree bank with constant airspeed, your G-loading will be the same whether you are climbing, descending, or maintaining altitude. For those who say a descending turn is less loaded than a level turn, that assumes you are allowing the airspeed to increase.

Click to expand...

At small angles of climb and descent, yes. At larger angles engine thrust and gravity mean the wing has to work less hard. Draw a vector triangle and 'do the math'.

Pete

Ironflight said:

Sorry Eddie, but the AoA is no more a crutch than the Airspeed indicator and a bunch of mental gymnastics to recalculate the current stall speed given the flight path, bank angle, gusts, etc, etc. The AoA does all of that compensation for you.

Ideally, we'd all be superior pilots who simply feel the airplane in the seat of our pants and never accidentally stall becasue we are one with the machine. That hasn't worked too well for a lot of dead folks over the last century.

If you want a reliable indicator of where the airplane is relative to the stall under all flight conditions, and you want that to be somethign other than your hind-quarters, AoA is the far superior instrument.

Click to expand...

What he said.


The wing stalls (potentially causing a fatal loss of control) at the same AOA, independent of weight, density altitude, loading, bank angle, or any of a zillion other variables.

The only reason we have an "approach speed" is because it is a rough proxy for AOA. If you know your weight (or are flying an airplane where it doesn't vary much) you can pretty much calculate the airspeed where you will reach the critical AOA.

Bank angle really has nothing to do with stalling speed or "g-loading," except that you have to load the wing to maintain level (turning) flight and if you do the g-loading required can be calculated from the bank angle. This is independent of the airplane, and the exact same chart can be used for any aircraft.

It's possible to stall the airplane from level flight at any speed up to the maneuvering speed by loading the wing (pulling back on the stick). That's how snap rolls work, if you add some rudder at the same time so one wing stalls first.

I think all the charts and numbers in the world combined with all the stall warning and AOA instruments don't hold a candle to some good old fashioned training in an aerobatic airplane if you really want to understand how an airplane stalls and spins at different attitudes/airspeeds.

I did mine in a Yak-52. My favorite part was accelerated stalls while banked over at 60 degrees, keeping it coordinated as best to keep it stalled. As soon as it goes out of coordination for a split second, it enters a spin. What a hoot.

I'd highly recommend it for anyone that has the opportunity. It sure helped me get a better "seat of the pants" feel for all the different airplanes I hop into now.

flyeyes said:

What he said.


The wing stalls (potentially causing a fatal loss of control) at the same AOA, independent of weight, density altitude, loading, bank angle, or any of a zillion other variables.

The only reason we have an "approach speed" is because it is a rough proxy for AOA. If you know your weight (or are flying an airplane where it doesn't vary much) you can pretty much calculate the airspeed where you will reach the critical AOA.

Bank angle really has nothing to do with stalling speed or "g-loading," except that you have to load the wing to maintain level (turning) flight and if you do the g-loading required can be calculated from the bank angle. This is independent of the airplane, and the exact same chart can be used for any aircraft.

It's possible to stall the airplane from level flight at any speed up to the maneuvering speed by loading the wing (pulling back on the stick). That's how snap rolls work, if you add some rudder at the same time so one wing stalls first.

Click to expand...

You can even stall the plane when you are pointing straight down, perpendicular to the earth.

Inverted is also interesting. Pulling back to recover from the stall is weird at first.

flyeyes said:

It's possible to stall the airplane from level flight at any speed up to the maneuvering speed by loading the wing (pulling back on the stick). That's how snap rolls work, if you add some rudder at the same time so one wing stalls first.

Click to expand...

Totally OT, but just wanted to point out that the idea that snap rolls are initiated by first stalling the airplane is widespread...and also wrong. This idea will lead to lots of terrible, slow, "buried" snap rolls that put unnecessary stress on the airplane. Proper snap rolls involve only a slight, but sharp AOA change, sufficient to cause the full rudder input to then stall one wing only. This is the key to the high rotation rate associated with snap rolls (along with a timely unloading of the stick after the snap breaks). Both wings do not stall, and the single wing stall is caused by the rudder input, not the elevator input. Yes, you can do what's essentially a "horizontal spin" by pulling the stick fully aft, stalling the airplane, and applying rudder, but it'll be so energy-killing, slow, and ugly that I would not classify it as a "snap roll". Sorry, I'm an acro nut to the bone.

And for those who might actually be interested - some snap clips I shot, showing the elevator inputs - which are fairly small compared to the full deflection range of the elevator: http://www.youtube.com/watch?v=g5et7jj2SiA

"You can even stall the plane when you are pointing straight down, perpendicular to the earth."

I'm curious about this one. If you're going straight down and increase AOA toward a stall you will no longer be going straight down. What am I missing here?

Numbers

These were the numbers I was looking for Vso being 50 mph.
Which are a formula from the load factor.
Obviously the variable of weight and CG changes the Vso.
Flight testing with various weights and CG
would be great data to see in a POH.

30 Deg Bank ~ Vso*1.07 = Stall appx 54kts
45 Deg Bank ~ Vso*1.19 = Stall appx 60kts
60 Deg Bank ~ Vso*1.41 = Stall appx 71kts
75 Deg Bank ~ Vso*2.00 = Stall appx 100kts

Great info here. Thanks.

flyinga said:

"You can even stall the plane when you are pointing straight down, perpendicular to the earth."

I'm curious about this one. If you're going straight down and increase AOA toward a stall you will no longer be going straight down. What am I missing here?

Click to expand...

Point the plane straight down and pull the stick back (or push forward towards the panel) in your lap hard. You'll continue to fall straight down and the wing will be stalled.

I agree with you though. If you point straight down and pull back without stalling the wing, the plane won't stall. I'm referring to something else entirely.

Aryana said:

How do you figure? Point the plane straight down and pull the stick back in your lap hard. You'll continue to fall straight down and the wing will be stalled.

Click to expand...

Well, your flight path will change (shallow out a little) for as long as you hold the stick back, but the point still stands that you can stall the airplane in any attitude.

sandifer said:

...but the point still stands that you can stall the airplane in any attitude.

Click to expand...

That's my point. The rest is semantics, but you're observation is quite astute and noted. I think for the purposes of understanding or teaching someone how/when stalls can happen, that slight change in flight path is moot.

agirard7a said:

These were the numbers I was looking for Vso being 50 mph.
Which are a formula from the load factor.
Obviously the variable of weight and CG changes the Vso.
Flight testing with various weights and CG
would be great data to see in a POH.

30 Deg Bank ~ Vso*1.07 = Stall appx 54kts
45 Deg Bank ~ Vso*1.19 = Stall appx 60kts
60 Deg Bank ~ Vso*1.41 = Stall appx 71kts
75 Deg Bank ~ Vso*2.00 = Stall appx 100kts

Great info here. Thanks.

Click to expand...

This is good info as a reference, but it doesn't even begin to scratch the surface in a practical sense. For example, it is possible to fly an approach at 60 in an RV-9 and roll into a 60+ degree bank without stalling the wing. The key to understanding why this is possible is far more valuable than memorizing a load factor chart.

?But this level of understanding is not going to come from debate on an Internet forum.