Sorry, Tyler I was being sarcastic. I should have included the tag.
pitch=airspeed; power=altitude
- Thread starter js0305
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Sorry, Tyler I was being sarcastic. I should have included the tag.
tgrayson
New Member
I'm not sure that would have helped. There's always someone who would have thought it was a good argument....
The title of the thread says "pitch", not "AoA". That's what I'm talking about as that is how it is frequently taught. "Pitch controls A/S."
I don't think I've mentioned elevator angle. I've only talked about pitch, i.e. the reading on the A.I. or the amount of space that you see between the top of the cowling and the horizon.
My bigger concern here is the idea that the only proper way to fly an airplane is by adjusting the pitch attitude in order to control airspeed. While that is ONE way to fly an airplane, it is not the only way.
tgrayson
New Member
But I did and you disputed it, but using the word pitch, which I do not use in this context.
Fresh start. Do you agree this chain of causation:
Yoke->Elevator Position->AoA->CL->Airspeed?
This is the connection made by every aerodynamics book that discusses the issue.
chensley
New Member
Pointy end towards the sky-slower airspeed.
Pointy end towards the ground-faster airspeed.
Power up-aircraft wants to climb.
Power down-aircraft wants to sink.
When I was a buck private, I asked my instructor that same question. He told me to go sit in the airplane with the engine off and see how high I go.
Use them both in tandem, now your in business =)
Pointy end towards the ground-faster airspeed.
Power up-aircraft wants to climb.
Power down-aircraft wants to sink.
When I was a buck private, I asked my instructor that same question. He told me to go sit in the airplane with the engine off and see how high I go.
Use them both in tandem, now your in business =)
tgrayson
New Member
Ok, then I'll feed YOU this one.
I've drawn a set of power curves below. The power available curve shows full throttle and the airplane is shown at a velocity that lies well behind the power required curve. How can this airplane establish a sustained climb?
Apologies for taking so long to get back to this.
Before going on with the discussion I'd like to ensure we agree on the two techniques being discussed:
Technique 1: Pitch (AOA) = Glide Slope (Altitude/Descent Rate) & Power = Airspeed
Technique 2: Pitch (AOA) = Airspeed & Power = Altitude (Glide slope/Descent Rate)
Do we agree on this being the two techniques under scrutiny?
Really when we list these techniques in this format, short and sweet, they merely define the response to a certain scenario. For example:
Technique 1: If we are sinking (scenario) we apply pitch (response). This will then result in a decrease in speed (new scenario) where we then apply power (response).
Technique 2: If we are sinking (scenario) we apply power (response). The result is the sinking being arrested and since no change in AOA occurred there was no change in speed.
Can we agree that the techniques defined are really just scenarios with a given response?
Now onto the quotes:
I understand what you mean. What I have a problem with is this, "difference is only in why you decided to make them." The reason I don't like this is because the reason why in one technique is right and in the other technique it is not.
I suspect this is why some of us are so adamant for the second technique listed above. One thing I find interesting is that few people, on the other side of this argument, will put there foot down and stand their ground as you have. Typically it is argued first that this one technique isn't entirely right and scenarios are given where it is claimed not to work and subsequently disproven. Then the good old, "everything controls everything" comes in as if it is an intellectual statement.
I commend you on standing your ground.
It doesn't sound like this proves the technique wrong, it sounds like he had a few problems:
1) Applied by rote. You have to think to fly.
2) Talking on radios. No, fly the airplane and then talk.
3) Lacked understanding of the application of the technique. (Along the same lines as #1)
His responses were proper, but overly applied. As it reads he appears to have the understanding that the only way to gain speed is to keep pushing the yoke forward. We both know this will eventually result in a loop and isn't actually how the technique is meant to be taught.
I suspect you would have done just as well getting him over this hump by teaching him how to properly apply the technique. For me, I like to ensure pitch is used to attain a flyable attitude. I use level flight because I know we can achieve an increase in speed with full power at level flight, at least well above Vy required to perform the climb out on the go around. It is also the attitude I use for stall recovery: IE pitch level > power full >etc
I am saying pitch controls AOA, because it does. What it doesn't do is control it uniformly. What I mean is if we pitch up 5 degrees without changing power the AOA will increase, not by 5 degrees, but it will go up by some amount and airspeed will decrease as a result.
Before going on with the discussion I'd like to ensure we agree on the two techniques being discussed:
Technique 1: Pitch (AOA) = Glide Slope (Altitude/Descent Rate) & Power = Airspeed
Technique 2: Pitch (AOA) = Airspeed & Power = Altitude (Glide slope/Descent Rate)
Do we agree on this being the two techniques under scrutiny?
Really when we list these techniques in this format, short and sweet, they merely define the response to a certain scenario. For example:
Technique 1: If we are sinking (scenario) we apply pitch (response). This will then result in a decrease in speed (new scenario) where we then apply power (response).
Technique 2: If we are sinking (scenario) we apply power (response). The result is the sinking being arrested and since no change in AOA occurred there was no change in speed.
Can we agree that the techniques defined are really just scenarios with a given response?
Now onto the quotes:
I understand what you mean. What I have a problem with is this, "difference is only in why you decided to make them." The reason I don't like this is because the reason why in one technique is right and in the other technique it is not.
I suspect this is why some of us are so adamant for the second technique listed above. One thing I find interesting is that few people, on the other side of this argument, will put there foot down and stand their ground as you have. Typically it is argued first that this one technique isn't entirely right and scenarios are given where it is claimed not to work and subsequently disproven. Then the good old, "everything controls everything" comes in as if it is an intellectual statement.
I commend you on standing your ground.
It doesn't sound like this proves the technique wrong, it sounds like he had a few problems:
1) Applied by rote. You have to think to fly.
2) Talking on radios. No, fly the airplane and then talk.
3) Lacked understanding of the application of the technique. (Along the same lines as #1)
His responses were proper, but overly applied. As it reads he appears to have the understanding that the only way to gain speed is to keep pushing the yoke forward. We both know this will eventually result in a loop and isn't actually how the technique is meant to be taught.
I suspect you would have done just as well getting him over this hump by teaching him how to properly apply the technique. For me, I like to ensure pitch is used to attain a flyable attitude. I use level flight because I know we can achieve an increase in speed with full power at level flight, at least well above Vy required to perform the climb out on the go around. It is also the attitude I use for stall recovery: IE pitch level > power full >etc
I am saying pitch controls AOA, because it does. What it doesn't do is control it uniformly. What I mean is if we pitch up 5 degrees without changing power the AOA will increase, not by 5 degrees, but it will go up by some amount and airspeed will decrease as a result.
Get a bigger engine! Duh.
Aviator1988
Well-Known Member
"pitch for power... power for altitude".......
Doesn't matter if I agree with it or not as it's irrelevant to the point I'm trying to make. The control inputs are the same, regardless of which technique is (properly) applied.
Additionally, I've been talking about pitch attitude; not the yoke position, elevator position, nor AoA. Pitch attitude is not listed in your progression.
I assure you, the technique does work. I'm trying to explain why but I think you're too caught up in the physics of flight to see that if the control inputs are identical, the physics must also be identical.
tgrayson
New Member
That's not true Larry. Behind the power curve, I'm pushing to climb, you're pulling. I'll post the diagram again, below. How are YOU going to climb if you don't do as I say?
But then adding power, for speed. This action results in both techniques having the same application.
The vital link that is missing is that a person who falls behind the power curve low to the ground is going to first react to what appears most life threatening. What is a pilot most likely to be threatened by: The ground quickly coming up at them or a 2 inch dial?
I would suspect the ground would get their attention and they would react to that situation by pulling up first. Then they might add power, but it might be too late as the pitch application may have already stalled them in which case power would be very bad without first reducing pitch. Worse, they might get tunnel vision seeing the ground coming at them with increasing rapidity and their teaching isn't working. They are thinking, "pull up for altitude." Then bang.
Finally, I want to stomp this before it starts; what about the stall warning horn? We have all read about gear warning horns going off and pilots ignoring them for entire flights in the pattern, subsequently landing gear up. So it is likely safe to say that with the ground creeping up rapidly would promote a stressful state that might also block out the stall horn and leave the pilot focused only on the approaching ground.
MikeD: Would this be a similar psychological scenario to "target fixation" you have discussed in the past? Adrenaline pumping and focused so intently on one goal that everything else is blocked out.
tgrayson
New Member
No, it doesn't, it just makes you climb. If you have enough power, it compensates for the increase in drag your AoA increase, but it remains true that the AoA increase was dysfunctional. Oodles of excess power can compensate for a myriad of mistakes.
Regardless, in the power curve I posted, there is no more power available.
nosehair
Well-Known Member
This is the point! This is the scenario that promotes the 'pitch to airspeed' philosophy.
It is not, however, any 'normal' approach scenario in which we are attempting to control a constant descent flight path.
The scenario you describe is under stall training. Realistic training in flying the airplane into the region of reverse command during the flare and touchdown.
Slowflying down the centerline of the runway at about three feet at just above a stall, using throttle and elevator, as necessary, will teach the proper response and use of those controls when the pilot is flying within that region of reverse command.
I say, as necessary, because the combination of these two controls is like the application of rudder and aileron to effect a turn. Sometimes, you want the turn coordinated, and sometimes, you don't, so the application of rudder and aileron is not always the same.
Primary students have difficulty using opposite rudder against aileron on final approach when they have been hammered to coordinate the rudder and aileron during the rest of the flight.
That's why they (we) need to understand how these controls work in different situations.
Flying in and out of the region of reverse command over the runway so that the student pilot can see and learn to respond with forward pitch to gain altitude when the airplane begins to sink, is the only way I know of to teach the response. You can't see that at thousands of feet up doing PTS stalls. They don't teach what we are supposed to be learning, or correlating, about landing approaches and stalls.
Another critical moment when we need to be able to 'automatically' go to the 'pitch-for-airspeed' mode is engine failure on take-off. Pitching for critical AoA's on climb-out and sudden reversals to best glide angles all promote the 'One-Size-Fits-All' method of flight school teaching because that's how the Army did it in WWII.
I mean, we all agree that it is the combination of the throttle and elevator that gets the job done, and the title of the thread is too simplistic, because... wait for it....here it comes.."It depends."
And if I understand correctly, a student pilot who is endorsed for solo in an aircraft must understand, and be able, to do a power off approach, such as in an emergency engine out approach, and be able to do a power on approach using power to make an extended downwind because of traffic.
So, a student pilot, before solo, should be taught these methods. Also, he should have demonstrated consistently that he:
1) In the early stages, recognizes approaching the 'region of reverse command', (getting low & slow) and is able to properly fly out of it, and
2) In the later stages, consistently demonstrates not allowing the airplane to approach the 'region of reverse command'. (successful outcome never in doubt)
So, if student pilots were taught both of these methods, as a normal standard technique to be used as appropriate, then...well, then we could get back to arguing about ( fill in the blank with you favorite drill).
irate:
The above example would be one form of target fixation, basically as described where tunnel vision towards getting a particular task accomplished or met, results in the person blocking out nearly everything else around them until its too late. In the case you describe, I assume the pilot is fixated on getting back around to the runway and is either fixated towards that or (mind) preoccupied with something else. All are different loss of SA types and could very well result in an "instant" recovery reaction that may or may not be correct. Many variables here and it does depend, but generally speaking this could easily fall under the target fixation umbrella.
I understand this, I was filling in the remainder of what I suspect his thinking is on how the techniques have the same end result.
Go try it. It works. The control inputs are the same.
Graphs and equations can't convince me that something that I can do is impossible. Especially true when the graph plots AoA, not pitch attitude. When performed correctly, the airspeed doesn't change so that means that the AoA is also unchanged.
If you're saying that you're already at full throttle in your scenario then power is fixed. See below. In that case, power is already full so you can't add power to climb, either.
You're only applying half of the technique.
The technique is "When power is available and variable, power controls airspeed, pitch controls flight path. When power is fixed, pitch controls either flight path or airspeed as needed".
When the engine fails, power is fixed. You pitch for either airspeed or flight path, whichever is more important at the time.
This is what I don't get. They work the same regardless of the situation so why tell the student they are working differently and why do you believe they work differently?
Pitch is never what is giving them their altitude so why convince them that it is. Instead why not explain that when they pitch they reduce their airspeed, sliding left on the power required curve, and subsequently having an increase in excess power. This is what is actually happening, why lie to them?
In other words, why not tell them something truthful:
Pitch > AOA > Airspeed
Excess power > altitude achieved by:
Increasing power
Changing airspeed to change required power
Changing airspeed to change required power
Telling them this allows them to use pitch to climb or descend. Except they do it with the knowledge of what is actually causing it and not with a faulty, incomplete, picture of how they are achieving a climb/descent.
Side Note: If you wish to throw momentum, or conversion of energy from K to P, to the make the above explanation completely accurate then go ahead. However, from what tgray posted earlier about that and my changes in thinking since reading that post, it seems like an unnecessary addition that just clutters the picture. In other words, either explanation will yield the same end result (picture) in understanding so there is no need to make it overly complex.
Will kill you. There is no ifs ands or buts about this one, trying to pitch for altitude will eventually kill you without an engine. The only link missing in this accident chain is fixation. Why put a student one link from death? That, to me, seems silly.