Thanks for your kind words. I’m glad I made that recovery as well.
For the record, I do know what I’m talking about when it comes to theses matters... I’ve been flying since 17, professionally since 21, am an ATP, CFI, CFII, hold multiple type ratings, I’m a Gold Seal flight instructor, have been an instructor at an airline, taught upset recovery and aerobatics, and am currently the Chief Pilot of the flight department for the company at which I’m employed.
I realize that we are just two nerds arguing on the internet, but I am interested in keeping the information in this thread as accurate as can be.
Just so we know, your experience in aviation is...?
For the record, I do know what I’m talking about when it comes to theses matters... I’ve been flying since 17, professionally since 21, am an ATP, CFI, CFII, hold multiple type ratings, I’m a Gold Seal flight instructor, have been an instructor at an airline, taught upset recovery and aerobatics, and am currently the Chief Pilot of the flight department for the company at which I’m employed.
I realize that we are just two nerds arguing on the internet, but I am interested in keeping the information in this thread as accurate as can be.
Just so we know, your experience in aviation is...?
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My first flight was from Bariloche to Buenos Aires in my country. (1500 KM) I was and still am a total neophyte on this subject. I was located just above the right wing. When the plane landed, (it was a Boeing 737, known here as "la chancha"), a piece of the right turbine detached, but fortunately a steel cable miraculously appeared and retained the piece, and even helped to slow down when landing, we all got out safely from that contingency ...
Perhaps the experts can explain to me what happened ...
My understanding is that airplane manufacturers spend fortunes figuring out (and trying to imitate) how birds do their incredible stunts. They take as an example the sustained flight in the air of the hummingbird, and all the theories bog down and remain unsolved. We are very far from the evolution that nature only gives in millions of years. And to top it all, it plays against human arrogance, that feeling that annuls all constructive dialogue, which we human beings carry inside. "Who are you?" Ha
Freud would feast on some.
Perhaps the experts can explain to me what happened ...
My understanding is that airplane manufacturers spend fortunes figuring out (and trying to imitate) how birds do their incredible stunts. They take as an example the sustained flight in the air of the hummingbird, and all the theories bog down and remain unsolved. We are very far from the evolution that nature only gives in millions of years. And to top it all, it plays against human arrogance, that feeling that annuls all constructive dialogue, which we human beings carry inside. "Who are you?" Ha
Freud would feast on some.
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Zero. But physics is physics.
You repeated back at me exactly what I said about zero g and a stall being different. You can have zero g in a plane and not be stalled - there’s a very good YouTube video on the subject I watched years ago about astronaut training for weightlessness. The plane flies a very specific profile and once ‘over the top’ it goes into a dive and everyone inside floats around until it bottoms out again. The wings are providing lift throughout the flight.
A stall means the lift has collapsed (no low pressure/ not enough low pressure over the top of the wing) to sustain flight. When the plane falls (not the same as a controlled dive as in a zero g flight profile) the occupants also experience zero g but with little chance of coming out of it in most cases - and especially so in a big airliner.
That’s my understanding and I believe it is correct.
You repeated back at me exactly what I said about zero g and a stall being different. You can have zero g in a plane and not be stalled - there’s a very good YouTube video on the subject I watched years ago about astronaut training for weightlessness. The plane flies a very specific profile and once ‘over the top’ it goes into a dive and everyone inside floats around until it bottoms out again. The wings are providing lift throughout the flight.
A stall means the lift has collapsed (no low pressure/ not enough low pressure over the top of the wing) to sustain flight. When the plane falls (not the same as a controlled dive as in a zero g flight profile) the occupants also experience zero g but with little chance of coming out of it in most cases - and especially so in a big airliner.
That’s my understanding and I believe it is correct.
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Doesn't zero g flight mean the plane has to accelerate with a vertical down vector at the same rate as the gravity acceleration? The ubiquitous 9.8m/s^2?
Jan
Jan
Jan,
The aircrafts vector with respect to the earth is not really relevant, in that zero G occurs when all forces are equal (As 6L6 pointed out) and is normally performed in a parabolic flight profile. This profile gives the longest state in zero G, but, it could just be performed in an ascending fashion then arrested before the descent occurs.
Cheers,
Greg
The aircrafts vector with respect to the earth is not really relevant, in that zero G occurs when all forces are equal (As 6L6 pointed out) and is normally performed in a parabolic flight profile. This profile gives the longest state in zero G, but, it could just be performed in an ascending fashion then arrested before the descent occurs.
Cheers,
Greg
Boeing 737-200
" La chancha " (the pork) was called like that because of its voluminous size in relation to the surface of the wings, the plane flew only because (experienced pilots told me, I suppose it is an exaggeration) it had powerful RR turbines.
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I think you're agreeing with Jan - arresting an ascent is accelerating downward (in the 'physics' usage of acceleration, if not common parlance).
Earl Grey,
That's a good point and he is. I just want it to be it to be clear that this is not necessarily downward. If I climb vertically, then push forward on the stick, the acceleration is away from when I was pulling back on the stick. But, the airframe is not moving downwards. I think if we having this discussion in person then that would be clear to everyone what each of us means.
Cheers,
Greg
That's a good point and he is. I just want it to be it to be clear that this is not necessarily downward. If I climb vertically, then push forward on the stick, the acceleration is away from when I was pulling back on the stick. But, the airframe is not moving downwards. I think if we having this discussion in person then that would be clear to everyone what each of us means.
Cheers,
Greg
Academia50 - do you mean the thrust reverser? See 2:24 -
Stunning Boeing 737-200 CLASSIC JT-8 reverse thrust and Val-d'Or landing!! [AirClips] - YouTube
Stunning Boeing 737-200 CLASSIC JT-8 reverse thrust and Val-d'Or landing!! [AirClips] - YouTube
I understand that the plane doesn't need to dive straight down, but it must have a down vector equal to gravity, no?
How else can you be zero weight?
Edit no that is not correct; the derivative of the speed vector must be equal to gravity. As in changing from ascent to decent when rounding the parabola.
Jan
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Exactly. You are already moving in the aircraft and that velocity will be acted upon by gravity. If that movement is upwards at the beginning of the parabola you’ll still be pulled down by gravity, obviously, but your movement through space will be upwards with your decaying vertical momentum, then downwards.
The entire time will feel as zero because the path of the aircraft and your path are equal.
The entire time will feel as zero because the path of the aircraft and your path are equal.
Auto correction !!!
I've been researching myself and the Boeing 737-200 turbines weren't Rolls-Royce, they were Pratt & Whitney JT8D 😀
“ The entire time will feel as zero because the path of the aircraft and your path are equal.”
Surely if you are just flying along straight this applies as well. As a passenger, your path will be the same as that of the aircraft.
Zero G is when the plan or the occupants are in free fall.
Surely if you are just flying along straight this applies as well. As a passenger, your path will be the same as that of the aircraft.
Zero G is when the plan or the occupants are in free fall.
Just when you thought your PR nightmare was over
Air Canada Boeing 737 Max suffers engine issue on ferry flight | News | Flight Global
Jim, just how common is this type of “situation”?
Air Canada Boeing 737 Max suffers engine issue on ferry flight | News | Flight Global
Jim, just how common is this type of “situation”?
Andrew - We are talking about when the acceleration on the aircraft (and occupants) are equal to gravity, I.E., zero-g, not unaccelerated steady-state flight. (1-G)
Although your statement is true, you’ve missed the critical bit of context that makes it relevant to the conversation.
Chris - How common? Not very.
Much more importantly, the fact is these aircraft will fly very well on one engine. They have to. The way that the certification and operational rules work is not only will they fly nicely on one, if you are so heavy and/or the atmospheric conditions are such that you can’t meet your performance limitations after an engine failure, you are not legal to fly it at all.
In a plane being ferried, (no revenue pax or cargo, I.E., empty but for crew and fuel) Such as this, an engine issue resulting in a crew-commanded preemptive shutdown is really just an inconvenience from an operational standpoint. I will bet that the crew was a combination of 1) disappointed that they couldn’t get the plane up to base to be put back into service 2) happy it happened on an empty flight and 3) having a blast in the plane doing the procedures you normally only practice in the sim.
Although your statement is true, you’ve missed the critical bit of context that makes it relevant to the conversation.
Chris - How common? Not very.
Much more importantly, the fact is these aircraft will fly very well on one engine. They have to. The way that the certification and operational rules work is not only will they fly nicely on one, if you are so heavy and/or the atmospheric conditions are such that you can’t meet your performance limitations after an engine failure, you are not legal to fly it at all.
In a plane being ferried, (no revenue pax or cargo, I.E., empty but for crew and fuel) Such as this, an engine issue resulting in a crew-commanded preemptive shutdown is really just an inconvenience from an operational standpoint. I will bet that the crew was a combination of 1) disappointed that they couldn’t get the plane up to base to be put back into service 2) happy it happened on an empty flight and 3) having a blast in the plane doing the procedures you normally only practice in the sim.
Return to the (DC-1) DC-2 (DC-3). Passenger airplanes were Tri-Motors, so if one engine failed two others would pull you through. TriMotors have issues. But somebody was looking at the new radial engines, their power/weight, and realized that ONE engine would suffice for a go-around on a fairly large airplane. That it would clear the tree at the end of the takeoff run, or clear most mountain ranges to get to a landing field.
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