4 ms·

After all the speculation about engine failure, it sounds like the culprit is a combination of poor design and pilot error. The "Feather System" was unlocked b

by jobu 12y ago

After all the speculation about engine failure, it sounds like the culprit is a combination of poor design and pilot error. The "Feather System" was unlocked by a pilot too early in the flight, then air currents caused it to activate in atmosphere instead of near vacuum - likely tearing the ship apart.

joezydeco 12y ago
But part of the flight procedure is to actually unlock the feathers slightly later in the flight - at Mach 1.4. The article states this is to make sure the feathers are operational before heading upward, but that seems like a really narrow margin of time to execute this test.
- malandrew 12y ago
  While speed is a factor, it isn't the only factor. The altitude at which they are unlocked matters as well. Moving at Mach 1.0 at a lower altitude could subject the plane to far greater forces than at Mach 1.4 at a much higher altitude, where the air is thinner. Furthermore, where the force is coming from probably also plays a role. The angle of the force applied to the feathers may change when the force is not coming from a fall, but is instead the result of the engines provide force from behind the fuselage.
osivertsson 12y ago
10-11 years ago I followed the Ansari X Prize a lot. I have a fuzzy recollection that Peter Siebold, the surviving pilot, actually designed and, at least in part, programmed almost everything related to pilot controls (and lots lots more!) on the SpaceShipOne. If pilot controls are similar on SpaceShipTwo and poor design of them is blamed in the final NTSB report, then I hope Peter doesn't put too much blame on himself. Peter Siebold has given and achieved so much on this project, definitely a hero of mine together with Burt Rutan.
hga 12y ago
Not poor design, the Feather System has to be unlocked at some point. And testing it early, at Mach 1.4 might be a really good idea before you (I assume) commit to needing it. And there's a good possibility removing its contribution to the center of pressure too early is what caused the destruction.
- thrill 12y ago
  Hard to say if poor design is a contributing factor or not - if the release mechanism is easily confused because it's a tiny little switch that looks just like all the other tiny little switches, then yeah, it may be poor design. In new endeavors, especially the often unforgiving aviation arena, frequent and focused training often makes up for poor design, or less-than-wonderful human factors engineering, or other recognized-after-the-event shortcomings - until it doesn't.
  - dfox 12y ago
    I would assume that in typical aircraft cockpit, most of the prominently placed tiny little switches are actually important and unimportant tiny little switches are the exception.

by jobu 12y ago

joezydeco 12y ago

But part of the flight procedure is to actually unlock the feathers slightly later in the flight - at Mach 1.4. The article states this is to make sure the feathers are operational before heading upward, but that seems like a really narrow margin of time to execute this test.

malandrew 12y ago
While speed is a factor, it isn't the only factor. The altitude at which they are unlocked matters as well. Moving at Mach 1.0 at a lower altitude could subject the plane to far greater forces than at Mach 1.4 at a much higher altitude, where the air is thinner. Furthermore, where the force is coming from probably also plays a role. The angle of the force applied to the feathers may change when the force is not coming from a fall, but is instead the result of the engines provide force from behind the fuselage.

osivertsson 12y ago

10-11 years ago I followed the Ansari X Prize a lot. I have a fuzzy recollection that Peter Siebold, the surviving pilot, actually designed and, at least in part, programmed almost everything related to pilot controls (and lots lots more!) on the SpaceShipOne. If pilot controls are similar on SpaceShipTwo and poor design of them is blamed in the final NTSB report, then I hope Peter doesn't put too much blame on himself. Peter Siebold has given and achieved so much on this project, definitely a hero of mine together with Burt Rutan.

hga 12y ago

Not poor design, the Feather System has to be unlocked at some point. And testing it early, at Mach 1.4 might be a really good idea before you (I assume) commit to needing it. And there's a good possibility removing its contribution to the center of pressure too early is what caused the destruction.

thrill 12y ago
Hard to say if poor design is a contributing factor or not - if the release mechanism is easily confused because it's a tiny little switch that looks just like all the other tiny little switches, then yeah, it may be poor design. In new endeavors, especially the often unforgiving aviation arena, frequent and focused training often makes up for poor design, or less-than-wonderful human factors engineering, or other recognized-after-the-event shortcomings - until it doesn't.
- dfox 12y ago
  I would assume that in typical aircraft cockpit, most of the prominently placed tiny little switches are actually important and unimportant tiny little switches are the exception.