Posted on 06/12/2006 5:14:57 PM PDT by Yo-Yo
Boeing unveils plans for trailing edge variable camber on 787 to reduce drag, save weight
By Guy Norris in Seattle
Boeing plans to test and develop a trailing edge variable camber (TEVC) system for the 787 which it says will reduce cruise drag and save the equivalent of between 340 and 450kg (750-1,000lb) in weight.
The fully automatic system, which is thought to be the first practical application of the long-studied variable camber concepts evaluated by both Airbus and Boeing since the 1980s, will be “completely transparent to the flight crew” says 787 systems director Mike Sinnett. Linked directly into the flight management system and digital flight control system, the TEVC will operate by deflecting the trailing edge flaps in 0.5º increments while in cruise.
The motion will be driven by an electric power drive unit integrated with the torque-tube driven flap actuation mechanism. Although the TEVC control unit will add around 35kg of weight, Sinnett says the predicted "0.4 count in drag reduction" will convert into approximately 450kg of saved weight. The system will be capable of moving the trailing edge through a 3º arc, with the edge being set up and down by as much as 1.5º either side of a neutral setting position.
Boeing says the TEVC initiative is possible because of the clean sheet design of the 787 flight control system (FCS), added to the adoption of the simpler flaps and the extension of the integrated FCS to include both vertical and lateral gust alleviation. The system also includes drooped spoilers which, for the first time, can be used to tailor the flow between the wing structure and the trailing edge flap. “We will control the slot very closely, which is what you use to re-energize the flow,” he adds.
Boeing also reveals it is also developing a new, integrated form of cockpit voice (CVR) and flight data recorder (FDR) into a single system dubbed the enhanced airborne flight recorder (EAFR).
Smiths Aerospace is to build the system under subcontract from 787 avionics prime Rockwell Collins as part of the communications and surveillance system. Building on the most recent developments of the digitally-based, solid-state CVR/FDR, the EAFR will “combine data acquisition functions and the FDR, and incorporate crash protected memory,” says Sinnett.
Although meeting the data collection and crash-protection requirements of the latest US Federal Aviation Administration mandates, Boeing’s original EAFR concept “didn’t meet the letter of the law” in some specific areas including power supply. “We had to work with the FAA to get an acceptable means of compliance with multiple sources of power by putting two on the aircraft,” says Sinnett who adds the EAFRs will be located “in the nose and one in back.”
Is that a pictograph of Quetzacuatl on the ground there?
What is AFTI?
The first thing I thought of when reading this was the 727 years ago that had the flaps partially extended in order to increase cruise speed. I also recall the crew got it upside down during this shindig but recovered to a safe landing. I also recall the pilot admitting he erased the CVR as he exited the aircraft.
That looks like urban sprawl in the desert near LAS.
All AFTI flight tests were performed at Edwards AFB, so I presume that is a suburb of Los Angeles.
There's more to that story. Their employer was running a contest among the flight crews to see who could burn the least amont of fuel. 727 crews knew that by putting the trailing edges out a little, and leaving the leading edges in they could reduce drag, thus improve their fuel numbers. This was accomplished by pulling a circuit breaker controlling the leading edge hydraulics.
This worked fine for a while.
On one flight (the one you refer to), the F/O configured the aircraft this way, but the F/E was new and didn't know about this. When he saw the open C/B, he reset it. This drove out the leading edges (while they were at cruise). I believe there was significant structural damage as well as numerous soiled seats.
The practice was then strictly forbidden.
I was just kidding of course.
An F-16 was used to test canards as a means to enhance maneuvering capabilities.
Now that you have our attention, would you mind telling us non-technical types just what happened to the flight when the breaker was reset?
Would Hoot Gibson and a certain TWA flight (840) in April, 1979 figure into this?
scary looking - but i guess it works
I didn't remember all the details but I do remember what you said. As I understand it, on a 72 the LE slats don't extend the same way each time they're deployed and as I remember this specific situation when the CB was reset an outboard slat extended causing the inverted upset. Is that somewhat correct?
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