Quote from: Kim Keller on 10/29/2013 05:44 pmThere is no point in having a gear retraction mechanism on a vehicle which only gets one attempt at landing.That depends. There does need to be some contingency for this type of vehicle. Shuttle had an auxiliary pneumatic system to force the gear down and lock. That’s one approach. Another would be an emergency retract option. The former is well understood and tested. The latter is unknown, but would also work provided the decision point was far enough prior to touchdown to execute a full emergency retract because there is no go-around for any gliding vehicle which is essentially low enough to be experiencing ground-effect. The choice comes down to complexity, mass and expense. But there obviously does need to be a contingency mechanism of some kind included in the design. Leaving the vehicle with no option is not an option - as demonstrated by this test flight. A controlled hard landing is preferable to an uncontrolled roll-flip-stop. That's one of the lessons learned. And better learned and addressed early before the vehicle becomes operational with crew and passengers.
There is no point in having a gear retraction mechanism on a vehicle which only gets one attempt at landing.
I'll be keen to learn more about SNC's options. It is easy to lose track of how many mock-ups they have made so far of Dreamchaser and which could be upgraded to serve for further testing or be completed as an operational vehicle. There's an ETA (Engineering Test Article) which we're discussing now. There's a FTA (Flight Test Article) which is under construction and I believe an Orbital Vehicle that is only planned? Weren't there previous mock-ups as well?
Anyway, I see you are emotionally involved from your "Go Dreamchaser! Go SNC!" salute,
... and a company getting millions-billions of government money should have never got it wrong.
Quote from: clongton on 10/29/2013 07:30 pmQuote from: Kim Keller on 10/29/2013 05:44 pmThere is no point in having a gear retraction mechanism on a vehicle which only gets one attempt at landing.That depends. There does need to be some contingency for this type of vehicle. Shuttle had an auxiliary pneumatic system to force the gear down and lock. That’s one approach. Another would be an emergency retract option. The former is well understood and tested. The latter is unknown, but would also work provided the decision point was far enough prior to touchdown to execute a full emergency retract because there is no go-around for any gliding vehicle which is essentially low enough to be experiencing ground-effect. The choice comes down to complexity, mass and expense. But there obviously does need to be a contingency mechanism of some kind included in the design. Leaving the vehicle with no option is not an option - as demonstrated by this test flight. A controlled hard landing is preferable to an uncontrolled roll-flip-stop. That's one of the lessons learned. And better learned and addressed early before the vehicle becomes operational with crew and passengers.I think a retract circuit is out of the question. Gear deploy comes very late in the approach, leaving very little time for crew assessment of the situation and reaction. What if the talkback fails, not the deploy? There's no time to sort it out. And, they have a final-approach workload to deal with on a vehicle with a high approach speed, high sink rate and less than awesome roll/yaw characteristics (typical of lifting bodies). They need to be focused on the runway and not have to even think about the gear position. The appropriate design choice would be a positive deployment mechanism that ensures gear down every time.
This is landing gear.I can't help but feel it's a simple component in use for nearly a century and a company getting millions-billions of government money should have never got it wrong.Video or not DC has dug their own grave here and will not move forward after CCiCap.I was a supporter.Unfortunately due to the economics of the situation 100% success was required here.
Quote from: Kim Keller on 10/29/2013 08:41 pmQuote from: clongton on 10/29/2013 07:30 pmQuote from: Kim Keller on 10/29/2013 05:44 pmThere is no point in having a gear retraction mechanism on a vehicle which only gets one attempt at landing.That depends. There does need to be some contingency for this type of vehicle. Shuttle had an auxiliary pneumatic system to force the gear down and lock. That’s one approach. Another would be an emergency retract option. The former is well understood and tested. The latter is unknown, but would also work provided the decision point wasn't far enough prior to touchdown to execute a full emergency retract because there is no go-around for any gliding vehicle which is essentially low enough to be experiencing ground-effect. The choice comes down to complexity, mass and expense. But there obviously does need to be a contingency mechanism of some kind included in the design. Leaving the vehicle with no option is not an option - as demonstrated by this test flight. A controlled hard landing is preferable to an uncontrolled roll-flip-stop. That's one of the lessons learned. And better learned and addressed early before the vehicle becomes operational with crew and passengers.I think a retract circuit is out of the question. Gear deploy comes very late in the approach, leaving very little time for crew assessment of the situation and reaction. What if the talkback fails, not the deploy? There's no time to sort it out. And, they have a final-approach workload to deal with on a vehicle with a high approach speed, high sink rate and less than awesome roll/yaw characteristics (typical of lifting bodies). They need to be focused on the runway and not have to even think about the gear position. The appropriate design choice would be a positive deployment mechanism that ensures gear down every time.Here you "3 green" no waiting...http://www.nasa.gov/centers/dryden/history/Speeches/lifting_bodies/lifting-2.html
Quote from: clongton on 10/29/2013 07:30 pmQuote from: Kim Keller on 10/29/2013 05:44 pmThere is no point in having a gear retraction mechanism on a vehicle which only gets one attempt at landing.That depends. There does need to be some contingency for this type of vehicle. Shuttle had an auxiliary pneumatic system to force the gear down and lock. That’s one approach. Another would be an emergency retract option. The former is well understood and tested. The latter is unknown, but would also work provided the decision point wasn't far enough prior to touchdown to execute a full emergency retract because there is no go-around for any gliding vehicle which is essentially low enough to be experiencing ground-effect. The choice comes down to complexity, mass and expense. But there obviously does need to be a contingency mechanism of some kind included in the design. Leaving the vehicle with no option is not an option - as demonstrated by this test flight. A controlled hard landing is preferable to an uncontrolled roll-flip-stop. That's one of the lessons learned. And better learned and addressed early before the vehicle becomes operational with crew and passengers.I think a retract circuit is out of the question. Gear deploy comes very late in the approach, leaving very little time for crew assessment of the situation and reaction. What if the talkback fails, not the deploy? There's no time to sort it out. And, they have a final-approach workload to deal with on a vehicle with a high approach speed, high sink rate and less than awesome roll/yaw characteristics (typical of lifting bodies). They need to be focused on the runway and not have to even think about the gear position. The appropriate design choice would be a positive deployment mechanism that ensures gear down every time.
Quote from: Kim Keller on 10/29/2013 05:44 pmThere is no point in having a gear retraction mechanism on a vehicle which only gets one attempt at landing.That depends. There does need to be some contingency for this type of vehicle. Shuttle had an auxiliary pneumatic system to force the gear down and lock. That’s one approach. Another would be an emergency retract option. The former is well understood and tested. The latter is unknown, but would also work provided the decision point wasn't far enough prior to touchdown to execute a full emergency retract because there is no go-around for any gliding vehicle which is essentially low enough to be experiencing ground-effect. The choice comes down to complexity, mass and expense. But there obviously does need to be a contingency mechanism of some kind included in the design. Leaving the vehicle with no option is not an option - as demonstrated by this test flight. A controlled hard landing is preferable to an uncontrolled roll-flip-stop. That's one of the lessons learned. And better learned and addressed early before the vehicle becomes operational with crew and passengers.
I was a supporter.
No way. You cannot just take a dump on an Air Force base. Executives talk very seriously about jail if this stuff happens. Rumored news that the NASA Commercial Crew guy quit:http://nasawatch.com/archives/2013/10/management-chan-2.htmlDoes anyone know if there are linkage to the test anomaly/failure?
Quote from: Jim on 10/29/2013 03:48 pmQuote from: Phyto on 10/29/2013 03:13 pmThis has probably been said but I don't know how, other than searching all the posts in this thread to find it. Were a pilot on board, both gear would have been retracted, if possible, Unlikely there would have been the capability to retract the gear. It is unnecessary.And what soft surface is nearby?If a pilot was onboard, the outcome likely wouldn't have been any differentcan you elaborate ?Not having the option to retract the gear on a piloted vehicle seems strange to me.I agree that the outcome would be the same, meaning a crashed vehicle, but the amount of damage is different when you belly flop or flip over, hard surface or not.
Quote from: Phyto on 10/29/2013 03:13 pmThis has probably been said but I don't know how, other than searching all the posts in this thread to find it. Were a pilot on board, both gear would have been retracted, if possible, Unlikely there would have been the capability to retract the gear. It is unnecessary.And what soft surface is nearby?If a pilot was onboard, the outcome likely wouldn't have been any different
This has probably been said but I don't know how, other than searching all the posts in this thread to find it. Were a pilot on board, both gear would have been retracted, if possible,
If the gear did not deploy there was also a system of explosives that would blow the gear off and allow the shuttle to perform a belly landing like an aircraft who’s gears have failed.