Article

2004-12-21 Home Front: Tech

Archived material is restricted to Rantburg regulars and members. If you need access email fred.pruitt=at=gmail.com with your nick to be added to the members list. There is no charge to join Rantburg as a member.

Posted by Steve White 2004-12-21 12:13:54 AM|| || Front Page|| [11133 views since 2007-05-07] Top

#1 Fly-by-wire biting asses?

Posted by mojo 2004-12-21 1:22:26 AM|| 2004-12-21 1:22:26 AM|| Front Page Top

#2 don't blame the hardware, it's the damn software I'll bet.

Posted by Rafael 2004-12-21 3:24:22 AM|| 2004-12-21 3:24:22 AM|| Front Page Top

#3 Could be pilot induced oscilation(sp?), but I thought they had that solved with training/software.

Fly by wire goes all the way back to the F-16, mojo. The hardware **should** be fully debugged by now. My guess is software, like R, or a random hardware failure.
IIRC, one of the early f-117s was lost bcause somebody cross-wired the pich/yaw gyros. It crashed on take-off like this.

Posted by N Guard 2004-12-21 4:14:53 AM|| 2004-12-21 4:14:53 AM|| Front Page Top

#4 Uh, guys - the software is part of the FBW system. Given that he ejected ok, I'd say it wasn't a roll problem like the old Widowmaker(grin), but something went south. Not enough info to guess.

Posted by mojo 2004-12-21 10:32:28 AM|| 2004-12-21 10:32:28 AM|| Front Page Top

#5 In my above post I am attemping (badly) to differentiate between implementation of flight control laws in hardware vs. in software. I'm sorry I didn't make myself clear.

On the older FBW birds the system was analog. 1970 vintage digital computers were too slow, and so the analog computers were specificly hardwired to each design.

The more modern airframes flight control systems tend to use (relatively) general purpose boxes. The flight laws were encoded, as opposed to hardwired. For an example, IIRC there was an experimaental SSTO rocket called Delata Clipper. It used the FCS box from the F-15c with some heavy modifications of the encoded flight laws. It made 2 or 3 takeoff and landing cycles b4 it crashed.

If I understand from the public lit on the F-22, all of the boxes are a general purpose design, with the software determining what each box does. so all it takes is some bad code, without actual mechanical failure to cause a crash.

Which is strange, for the flight laws like the contrl wiring should be debugged by now.

Oh well, the cause will come out in the accident review. I'm glad the pilot got out OK.

Posted by N Guard 2004-12-21 11:54:25 AM|| 2004-12-21 11:54:25 AM|| Front Page Top

#6 So that's what happened to Delta Clipper.

Posted by Shipman 2004-12-21 3:38:26 PM|| 2004-12-21 3:38:26 PM|| Front Page Top

#7 Anyone driving along N. Las Vegas Blvd. by the speedway would've probably seen the mishap. Great place to watch the goings on at Nellis, btw.

Posted by Bomb-a-rama 2004-12-21 4:46:21 PM|| 2004-12-21 4:46:21 PM|| Front Page Top

#8 Oooh! At 260 million dollars apiece, you just know somebody is going to get their knuckles popped!

Posted by smn 2004-12-21 7:33:55 PM|| 2004-12-21 7:33:55 PM|| Front Page Top

#9 This could also be a case of shit happens. Some accidents are just that

Posted by Cheaderhead 2004-12-21 9:37:35 PM|| 2004-12-21 9:37:35 PM|| Front Page Top

#10 Couldn't this also be a thrust-vectoring problem? If the thrust-vectoring cut in when it wasn't supposed to, it probably would have killed enough thrust to keep the aircraft from flying.

Dono how T/V works in the bird, but suspect it is linked to the F/C puter, so that points back to a puter problem.

Could've also been a plain old fuel delivery thing, too.

Posted by Rivrdog 2004-12-21 10:04:38 PM|| [http://rivrdog.typepad.com] 2004-12-21 10:04:38 PM|| Front Page Top

#11 that damn Citgo 87 octane unleaded....

Posted by Frank G 2004-12-21 10:07:27 PM|| 2004-12-21 10:07:27 PM|| Front Page Top

11:32 Mrs. Davis
11:32 Mrs. Davis
00:20 True German Ally
00:05 Poison Reverse
00:00 True German Ally
23:51 Richard Aubrey
23:47 Aris Katsaris
23:45 Poison Reverse
23:42 Poison Reverse
23:42 leaddog2
23:39 Brett_the_Quarkian
23:38 Brett_the_Quarkian
23:36 Poison Reverse
23:32 Poison Reverse
23:31 Brett_the_Quarkian
23:23 Poison Reverse
23:13 True German Ally
22:44 Capt America
22:41 Ptah
22:40 Ptah
22:33 RWV
22:25 Frank G
22:24 Aris Katsaris
22:21 Fred