Hey Bob, I have heard some stories about the 727 another Boeing workhorse. I may have the details wrong but there is a story where the Flight Engineer was in the back and the captain wanted to climb higher than the book said they could. He got the idea to pull the breaker on the slats and extend just a little trailing flaps. All was ok until the engineer returned, saw the white collar and reset the breaker. They went into a supersonic spiral also. Finally threw the gear out and recovered. Dave
Keep the anecdotes comin'! In the meantime . . . Can one or two or three of you pilots use the two above words in a calm, even monotonous sentence, geared towards passengers? *ding*
Thanks Dave. You are refering to the " Hoot Gibson incident" where by going to trailing edge flaps deployed a few degrees they could get a better cruise L/D but in a 727 the trailing edge flaps are normally coordinated with the leading edge slats and flaps. To deploy just the trailing edge flaps the breaker has to be pulled on the leading edge system and that was done. The flight engineer was back in the can, the way the story goes, and as he was returning he noticed that the breaker was" popped" on the leading edge stuff and thoughtfully re-engaged it thus deploying them. The result was almost fatal since the load on the LE devices was beyond their capabiilty and they collapsed. The airplane went into a spiral dive but they somehow recovered it. My son was a flight engineer on 727's and he and I walked me through the procedure some time ago but I think that I remember it well enough to recite the original incident. The LE devices coupled with the triple slotted trailing edge flaps on the 727 are most powerful, they double the lift coefficient of the wing when they are driven through the air at 80% thrust. To deploy part of them at cruise Mach is deadly. I might add that the modern airfoils on things such as the 787 are aft loaded sections that do to perfection what the 727 guys were trying to do with TE flap manipulation. Hope that this answers your question. Switches
Similar story, though with passengers. Imagine being on this 727 that dropped 34,000 feet in 63 seconds. That will wake you up I bet.. http://en.wikipedia.org/wiki/TWA_Flight_841_(1979)
I don't know that there is anything such as a supersonic spiral. When an airplane nibbles at Mach 1 and it isn't configured for speeds beyond Mach 1 they do funny things, one of which is a spiral dive but it usually isn't super sonic. A super sonic vehicle remains somewhat stabile when it achieves that speed. The 707 in the Gander dive was reported to have exceeded Mach 1 but it was a clean machine and was going down with cruise power still applied.
Feeling a bit professorial this morning so I drew a little sketch of the 727 high lift system to show how powerful it was.and to show the game that some 727 pilots played with the flap incident mentioned above. The four slots produced high velocity low pressure bands of air that maintained attached flow at high angles of attack and low speeds. The 727 was designed to land at short fields but to also cruise at high speeds in between hence a small wing and big flaps. Image Unavailable, Please Login
Nice drawing Bob. I was lucky enough to fly copilot on the 27 for three years. To date it is probably the most fun airplane I have ever flown. It didn't climb worth a darn but boy would it go fast. I remember going into Portland Oregon and ending up high on the visual. I told the Captain I would need an S turn to get down. He says "No need, you ready for 40 flaps?" Came down like an express elevator. The 27 would go fast and it would go slow (both requiring a lot of fuel). Dave
Thanks. I worked many hours of overtime on that airplane and taught 727 familiarization to over 2000 people. It was quite a departure from the 707 series and it was a good airplane. The wing was a masterpiece with powerful high lift devices and a continuous panel from the center section to the tip and devoid of struts and engines to foul the air flow over it. It did exactly what is was designed to do and with a high rate of reliability. Little wings don't do climbing too well, I guess. I remember the UAL incident where a high rate of descent was not coupled with enough power to make an arrest and the airplane was belly-flopped into the runway at Salt Lake City. That high lift system works only when it is driven through the air and that takes a lot of power as you know. Switches
