If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Pinging Ron Wanttaja - "Unporting?"
Ron,
I posted this over on RAP but apparently managed to stump everyone. I thought that perhaps some of your contacts at Boeing might know if this word, "unporting" was misused by Gann, or is an old term that is no longer used. It just doesn't sound right to me. -- Bob (Chief Pilot, White Knuckle Airways) Post 1: I was reading Gann's "Fate is the Hunter" again the other day, and was curious about the incident in the last chapter where he unintentionally and naively avoided disaster by NOT slowing down when the DC-4 he was flying from Hawaii to Burbank developed an unexplained occasional vibrational "shudder". Later an engineer called him a very lucky pilot, and described to him a scenario that he called "unporting" which was an uncontrolled dive caused by lose of "balance" between the fixed and movable parts of the stabilizer, which could not be recovered from. His plane had a missing hinge bolt in the stabilizer, and had he reduced power, which was the natural reaction to an unknown vibration, this "unporting" would have occurred. Another plane on the same day crashed from the same phenomenon, and all DC-4's were grounded worldwide immediately afterwards once this phenomenon was understood. My interest is the word "unporting". It doesn't sound right. I'm an engineer (biomedical), but not an aeronautical engineer. You aerospace engineers out there, is this the right term? Gann was not mechanical, and I was wondering if he got the term wrong. If not, can someone explain how the term is (or was, back then) used in aeronautical engineering? What is the "port" it refers to? I'm curious. Post 2 in response to several replies that referred to unporting of fuel tanks: I'm well aware of the use of the term "unporting" to describe loss of fuel flow from a tank because of low quantity, perhaps coupled with a slip or high angle of attack. The use of the term I was curious about was to describe an aerodynamic condition at the stabilizer that caused loss of control. See the quote from the book below. Quote: Then he sat beside me and drew out a pencil. And while he talked, he made notations and diagrams on the tablecloth, each line and figure neatly set down after his hands had flown their interpretation. He began by saying that my written report on the suspected vibration had been a masterpiece of innocence. He stated flatly that if I had any training as an engineer, I would never have had the opportunity to write it. It seemed that only a most remarkable series of causes and effects had kept us from duplicating the catastrophe of Bainbridge. The aura of fantasy was compounded when we considered both had occurred on the same day. "Did You know we grounded every DC-4 in the world because of you?" he asked. "I've been sailing." "Never giving a thought to vibration, of course." "No." "Thank you for completing my picture of blessed ignorance." He frowned and his hands fluttered uncertainly. "But I will never understand your nonchalance. Listen to me very carefully. I've spent too much time on this investigation to miss the finale." It soon became obvious that Howard's detective work had included my personal anticipations. Even what I had said to the crew and passengers had been remembered and considered. "Although we can never be absolutely certain, we now believe the Eastern Airline crash at Bainbridge was caused by unporting. Do you know what that is?" I confessed that I had never heard of it. "Unporting is the balance destruction of the elevators by aerodynamic force. I won't confuse you with theory, but if enough separation between the fixed and the balance portion of your elevators occurs, your airplane will go into a vertical dive or even beyond the vertical, and no two men in the world are strong enough to bring it out. This can be caused by a missing hinge bolt." He sighed heavily and drew wavelike lines on the table, then an airplane diving for the lines. He sketched another airplane more precisely and marked its approximate center of gravity:: slow down when you first noticed the vibration? You did not because you had no fear of it. But if you had been the nervous type, if you slowed down, the center of gravity would have changed. That would have been quite enough to complete the process of which had partially begun." "The vibration really wasn't very bad." "It doesn't take much. But let us assume another pilot would have reacted in the same way. It would only have postponed the inevitable. As soon as the time came for a normal power reduction and it was accomplished, unporting would begin. But not you. In the past you had lost all four engines so many times, the prospect of losing one gave you relatively little concern. So you sat there, fat, dumb, and happy, and you cancelled all power reductions. This brilliant decision saved your life the first time that day." I could think of nothing to say but a series of well. well's. "This was not enough," he said, and I saw that he was exasperated. "You landed at Burbank and disembarked twenty-one passengers. God alone knows why, but you took on just enough fuel to make up the difference in losing their weight. Even so your center of gravity would have changed enough so that unporting was more likely than not. But." He moved a third finger up beside the others. "You were in a hurry to reach Oakland so you could go about your silly sailing. As a result, and don't deny it because the figures are in the logbook, you used full gross weight cruising power all the way and your speed was correspondingly high." He paused, touched at his moustache, and stared at me incredulously. Then he spoke very slowly, clipping off each word as if he intended to impress them on my memory forever. "I would look at you quite differently if I thought you had planned what we eventually discovered. We had some long sessions with our slide rules and we found, my friend, that you had arranged the only possible combination of power, speed and weight which would blockade the chances of unporting." Later, when the wine had mellowed us both, I asked Howard if his slide rule could measure the fate of one man against another's. Fate is the Hunter Ernest K. Gann 1961 |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Pinging Tommy Cooper | Bob Chilcoat | Home Built | 0 | September 30th 03 08:28 PM |
KitPlanes - Home Page by Ron Wanttaja | RobertR237 | Home Built | 40 | August 12th 03 10:17 PM |