@hippyjoe1955 they go hand in hand

@Heartlander

When teaching canoe paddling, the center of gravity is always placed as close to the waterline as possible, which means to enter a canoe, you grab both sides simultaneously while kneeling onto the floor of the canoe in one continuous motion, but you do not EVER sit not those cross-members which look like seats. They are not seats!

Those cross-members are what you lean your butt up against while physically placing your weight on your knees which rest in the bottom of the canoe at all times, thereby lowering your center of gravity as far as possible.

If you have your knees at the bottom of the canoe where they're suppose to be, there's never a question of where your center of gravity is located. That's straight from canoe paddling 101.


What you were looking at on YouTube as described, are vessels that have "capsized", not "keeled over".

To capsize means to lie on it's side with half the deck submerged, but still floating.The correct nautical term for this condition is called "On her beam ends" in reference to large ships versus boats. Boats are 'capsized', whereas ships are "On her beam ends" when both are in this state.

Nautical terms change from boats to ships, i.e: A boat has a propeller whereas a ship has a 'screw'.

The term "keel over" means that a complete roll-over has occurred and the vessel is upside down and is still floating, hence the term "keel over", meaning the keel has rolled over from bottom to top, to come to rest with the keel in the top (fully inverted) position with the vessel still floating.

The term "list" means to lean more than 45 degrees, but without dragging the gunnel in the water. As soon as the vessel's gunnel is in the water, the vessel is deemed to be "capsized" or "On her beam ends".


Not quite! People who fall over drunk have nothing to do with nautical terms, though nautical terms are often used to describe someone who is drunk.

Drunken sailors of long ago, likened a fellow sailor's state of situational awareness to the familiar condition they all knew a ship could find itself in when the ship became disabled at sea.

For a fellow sailor to "keel over" while in a bar for example, meant that the drunken sailor passed out drunk, then fell off his chair or simply collapsed while standing at the bar and ended up face-first on the floor, hence 'upside down' from his previous position of sitting upright on the chair or standing at the bar.

Lying face-first on the floor is the 'prone' position.
Lying on one's back and staring at the ceiling is called the 'supine' position.

A sailing vessel that has it's sail lying in the water is a "capsized" sailing vessel that has taken on water to the point where the weight of it's keel is not heavy enough to 'right' the vessel.

This is because the weight of the water inside the hull is now heavier than the steel keel itself which counteracts the normal weight of the sailboat through it's inherent pendulous action of 'self-righting'.

In this situation that you describe seeing on YouTube, the sailboat has momentarily capsized (but not keeled over) then began to 'Founder' which means to fill with water until the weight of the water exceeded the weight of the vessel's keel, at which point the sailing vessel is deemed to be "Foundering" which means taking on water and becoming submerged but has not completely sunk yet which is what you were looking at on YouTube.

This situation for a sailing vessel typically results from someone leaving the main hatchway open and unlocked thereby enabling water to flow in should the sailing vessel momentarily capsize, but capsize just long enough for water to suddenly flow in to cause 'BALANCE' to occur between the vessel's hull and her keel.

Take this to mean that a sailing vessel is intentionally designed to be inherently out-of-balance for the pendulous action of 'self-righting' to be effective. As soon as 'balance' occurs from Foundering, the heavy steel dorsal keel of a sailboat will not 'right' the vessel after it capsizes.


Both statements are incorrect. The term "Positive Dihedral" is a term that is used to describe the degree to which the wings are designed to have an upward sweep, like the raised wings of an eagle in flight. The higher the up-sweep, the greater the 'positive dihedral' that is designed into the wing, the more stable the aircraft inherently is by design.

A Boeing-747 for example is designed this way, which is why pilots call it an 'old man's airplane'. You can manually put the airplane into a bank, then take your hands off the controls and the airplane will inherently return itself to a straight and level configuration without assistance because of it's 'positive wing dihedral'.

This also prevents a 747 from entering into a spin because the down-wing wants to 'right' itself to the straight and level attitude because of the positive dihedral that's built into the wing design, thereby eliminating an incipient spin from even coming close to developing.

The 737Max was designed with an inferior, automatic anti-stall system that pushed the stick full-forward if the system detected the wings were at a high angle of attack, regardless of manual flight or automatic flight being conducted at the time, which could not be turned off by the pilot nor be overridden by the pilot using extreme back pressure on both control columns to avert the ensuing vertical dive of a false stall recovery initiated by the automatic system.

The DC-10 like all other pressurized commercial aircraft, used plug-type doors throughout the fuselage except for the cargo doors which were not plug-type doors, but were instead held closed by 2 mechanical latches despite the cargo compartments themselves being fully pressurized during flight.

Anytime one or both mechanical latches either broke or were not fully engaged properly after being closed by ramp personnel, as soon as the aircraft became pressurized in flight and that outward pressure then increased against those cargo doors as altitude was gained, the remaining latch holding a cargo door closed would then break causing the door to explode wide open with such force as the aircraft depressurized, that the passenger floor would cave in and fall down onto the flight control cables which run under the floor from the flight deck to the wings and tail, immediately jamming those cables in their last set position by the pilot, or moving them significantly which nonetheless caused loss of control of the aircraft by the pilot each time this happened.

@swirlie

:) My credentials in canoeing for that summer was a Boy Scout canoeing merit badge earned years earlier. That and a a "how to" type manual and I was in. That camp also had a couple of small row boats for life guard duty monitoring kids who swam out a distance from shore. We never used them as row boats but instead used them as paddle boats while sitting on the peak of the bow, which lifted the back of the boats to level with the water and making the rowboat as easy to move around as a small shopping cart at the supermarket.

Almost ...

If someone was to reference a 747 as an "old man's" airplane I would assume it was because of airline seniority systems. Pilot pay for most (possibly all) union pilots is a convoluted formula based on such things as cruise speed, night or day, max gross weight, block to block hours, duty hours, trip hours (and probably something else added over the past 40 years). A 747 being extra heavy, having extreme range by comparison (i.e. long flight legs) pulls top pay and easiest flights for for the pilots, making it prime bidding aircraft for the most senior pilots. At least until the big Air Busses came along.

While the upward angle wings may create a natural straight and level groove, the consideration for where to put the wings (and tail) and how to slant them is probably more related to protecting the airplane from dangerous yaw angles (as would occur with gusty winds, heat thermals, downdrafts, turbulence, engine failures, etc.) especially at lower speeds and within a few thousand feel of the ground.

Example: an engine fails, the airplane yaws abruptly and the big fuselage partially blocks the wind over the wing with the inoperative engine. That wing stalls, the other wing doesn't and the airplane rolls. All multi engine, non-centerline thrust airplanes face that potential, but swept wing planes are more at risk, as are larger airplanes.

In a swept wing plane, when the airplane departs from being parallel to the relative wind, the two wings are at different angles to the relative wind which translates into unequal lift. One wing wants to go up and the other wants to go down.

Make that at any speed. In a previous life I tracked aircraft accidents and there was a case where a 707 on a training flight attempted a practice engine out approach by retreating one outboard engine to idle. On leveling after a descent, the pilot advanced three throttles to maintain speed, leaving the simulated engine out in idle, and what I described above happened. The plane rolled and crashed. Even today, 40 years separated from airplanes and crashes still catch my attention, and the last two to do so were variances of the above. One was an engine failure that led to a vertical fin stall, another was an attempt at a 3 engine takeoff where the airline tried to move an aircraft with an inoperative engine to a maintenance location.

The cause of the 737Max issues is probably more related to a Boeing failure. Wasn't the chief pilot indicted for fraud, and Boeing itself hit with a criminal penalty?

I missed that horrible DC10 Chicago crash by 2 days..


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@Heartlander

🤣... I knew I would get your attention with that one!

A friend of mine is actually a female pilot with KLM who flies the 747 and she said the 747 has always been known in the industry as an "old man's" airplane because it is so easy to fly, not because of the seniority system that eventually puts them all there!

The airplane was designed with the seniority system in mind however, because Boeing Engineers knew that young new-hires would not be flying it, but instead was an airplane that only the very senior of the top 10% would be flying in most North American airlines.

With that in mind, the airplane had to be designed with a declining level of flying skills in mind, not an increasing level of flying skills as would otherwise be the case for new-hires.

The airplane was therefore designed for pilots in their last 5 years of their airline career, not their first five years. This means the pilot would really have to go out of his way to hurt himself in a 747 because the airplane is so docile in every regime of flight compared to any other commercial aircraft, including multiple engine-out scenarios.


No, not so. According to my own design research of the 747 from it's early beginnings, the positive dihedral (upsweep of the wings), is actually a design feature to make the aircraft "inherently stable, thereby constantly seeking level flight". The upsweep is not there to protect the airplane from dangerous yaw angles during engine-out scenarios.

Because the tail fin is located so far aft of the vertical axis of the airplane of a 747, the issue of dangerous yaw suddenly occurring is not actually possible, even if the rudder was rendered totally inoperative.

In other words, the vertical tail fin is located far enough 'aft' that yaw is prevented from occurring beyond 10 degrees left or right of center with no opposite rudder being applied during an engine-out maneuver.

Keep in mind that ALL jet engines will flame-out on any jet aircraft if yaw is induced and the yaw angle reaches 20 degrees left or right of center. This is because the airflow entering into the front of the engine nacelle is too sharp, which then causes the compressor blades to stall, followed by flameout of the engine, regardless of what side of the fuselage the engines are mounted when the yaw is induced.

The 747 has two rudders, one mounted above the other which work simultaneously, but which also work independently from each other while using independent hydraulic systems as their hydraulic sources. A manual rudder pedal direct cable connection is also available should a total hydraulic failure occur, which is connected only to the lower rudder, but not the top one. Manual rudder trim is also part of that feature.


Most of what you've written in your above quote is not actually true. In fact, you've taken small airplane, straight-wing theory of flight and applied it to high performance, very large aircraft, swept-wing operating principles.

During a left engine failure of a 747 for example, if the left wing drops while the pilot was manually hand-flying the airplane, because of the upswep positive dihedral of the wings, as the left wing theoretically drops, it actually becomes more stable because it is now flying in a 'level state' compared to it's upswept state prior to the engine failure.

The right wing now moves higher as the left wing drops, but because the right wing was already in an elevated state from the upswept positive dihedral design of the wings, it actually becomes more UNSTABLE and develops LESS lift than the opposite wing with the failed engine, which is sitting in a state of level flight!

As a result of the left wing being more level than it was in the first place, it now develops MORE lift than when it was swept upward.... and the right wing is now developing LESS lift than it was before it was abruptly raised higher from the yaw angle that was theoretically induced...

...which means the right wing wants to DROP because of it's decreasing lift from being raised and the left wing with the failed engine wants to RISE because of it's increase in lift from being in ending up in a state of level flight compared to it's opposite wing with exaggerated positive dihedral angle!

What the pilot ends up with is the 747 wanting to return to it's inherently stable state of level flight as the wing's positive dihedral try to return the attitude of the airplane to straight and level flight, even with multiple engine failures on the same side of the aircraft.

Additionally, a swept-back wing of a jet is designed that way so that the wings themselves can be made shorter in length while creating just as much lift as a wing that was straight but much longer in length, to achieve that same amount of lift.

This is because the airflow over a swept-back wing traverses the wing at about a 20 degree angle, which means it travels a greater distance from leading edge to trailing edge if flows across the wing at an angle, versus across the wing at a perpendicular angle like it would otherwise do if the wing was straight and not swept-back.

As a result of this greater distance when airflow crosses over a swept-back wing at a 20 degree angle from lead to trailing edge, more lift is generated than if the airflow crossed that same wing dimension at a perpendicular angle. This is because it has to travel further and the airflow's aerodynamic affect is thereby increased.

The greater the sweep-back angle of a wing, the shorter the wings can be to achieve the same amount of lift as would otherwise be achieved from a straight wing that is longer in length.


The reason the airplane rolled and crashed was because of gross mishandling of the controls by the pilot in failing to apply opposite rudder to counteract the asymmetric thrust condition set up by the simulated engine failure, NOT because that's what typically happens during an engine failure on a multi-engined, swept-wing, jet transport airplane!


What you're making reference to here has nothing to do with an engine failure that caused a vertical fin stall.

The only way a vertical fin can stall is if the airplane is a T-tailed aircraft, such as a DC9... AND the nose is raised SO high that the airplane's wings both stall and the high fuselage angle then blocks the airflow from reaching the T-tail, thereby blanketing the entire fin including the rudder from the airflow, thereby preventing the aircraft from recovering from the stalled condition.

This is because forward movement of the elevators are now ineffective because of the blanketing affect caused by the fuselage, which means a stalled wing condition is non-recoverable on ALL T-tailed commercial aircraft. That stalled condition is known in the industry as a "deep stall", which means non-recoverable.

A vertical fin will not stall unless the fuselage blocks the airflow from reaching it.

You can see how that would happen from this photo of a DC9.





It was definitely a Boeing design failure. It was determined that the angle of attack sensor which is mounted on the side of the fuselage, was stuck in a weird angle after being parked on the ground, but in both cases that sensor never corrected itself during takeoff when the airflow was suppose to make the sensor correctly align with the airflow.

Instead, the sensor remained stuck at a sharp angle from being parked and when the airflow pushed it further into a sharper angle, the computer sensed that the airplane was stalling which was a false indication, so the automatic 'stick pusher' activated and tried to lower the nose despite the pilot's efforts in both cases from pulling back on the stick to pull the nose back up!

In both cases, the pilots were unable to overcome the 'push' forces from the computer by using manual 'pull' forces exerted on each control column simultaneously by both pilots in both cases.




That occurred in Chicago in 1979. It occurred because of a non-standard protocol the airline was using to remove and re-install a jet engine while in maintenance.

When the left engine subsequently ripped off during rotation at takeoff, the engine flipped up.. and over the top of the wing, landing on the runway behind the DC10, but when that happened, it also ripped out the hydraulic lines to the left wing as well.

With the hydraulic lines now ruptured, the slats on the left wing immediately retracted because they were held in position by hydraulic pressure, not mechanical locks. This was a design fault to have hydraulic pressure holding the slats out, unlike Boeing which used hydraulic pressure to un-lock those slat locks during slat-retraction after takeoff. If the hydraulics failed, the slats would remain extended because of the slat locks.

With the slats now retracted on the left wing-only but still extended on the right wing, the stall speed of the left wing suddenly increased by 25 knots, which meant the left wing immediately stalled and then rolled to the left as the left wing went down as a result of the stalled condition of the left wing, NOT as a result of the engine separating from the wing on the left side.

Had the slats NOT retracted, the aircraft would have climbed away without further incident on two engines... using the right engine and the centerline thrust engine on the tail.