Imagine how dumb you’d look if you had one of these scenarios happen where the crew could’ve been rescued but they can’t. “I thought you said the port was androgynous?”“Well, see the thing is...”
QuoteI just don't think there is such a thing as a capsule going to rescue another capsule.And there can't be, if they aren't capable of being docked to.
I just don't think there is such a thing as a capsule going to rescue another capsule.
Quote from: Robotbeat on 03/31/2020 07:17 pmImagine how dumb you’d look if you had one of these scenarios happen where the crew could’ve been rescued but they can’t. “I thought you said the port was androgynous?”“Well, see the thing is...”Quote from: whitelancer64 on 03/31/2020 08:02 pmQuoteI just don't think there is such a thing as a capsule going to rescue another capsule.And there can't be, if they aren't capable of being docked to. Pretty OT, but is an EVA crew tranfer (spacewalk to another veichle) possible for a rescue mission?
This latter sentence seems false. For instance:Original plan is Gateway goes up first. Both lander and Orion need active systems to dock to the passive gateway. But! Current plan is to skip Gateway and dock directly to each other for the first mission, and then *later* go back to the original plan (so that the lander ascent stage can be docked to Gateway between missions for reuse). So, given NASA's current plans, the lander at least MUST be androgynous if we're to keep its configuration the same.
Quote from: Robotbeat on 03/31/2020 08:22 pmThis latter sentence seems false. For instance:Original plan is Gateway goes up first. Both lander and Orion need active systems to dock to the passive gateway. But! Current plan is to skip Gateway and dock directly to each other for the first mission, and then *later* go back to the original plan (so that the lander ascent stage can be docked to Gateway between missions for reuse). So, given NASA's current plans, the lander at least MUST be androgynous if we're to keep its configuration the same.I read "HLS_Appendix_H_BAA_2019-10-02c.pdf" page 9, CLIN 009 - Option A: Docking System. Work on a detachable docking adapter... As to mean an adapter to make a port on the gateway active instead of passive. How do you read that?
Quote from: Robotbeat on 03/31/2020 07:17 pmImagine how dumb you’d look if you had one of these scenarios happen where the crew could’ve been rescued but they can’t. “I thought you said the port was androgynous?”“Well, see the thing is...”It isn't sane for the contractor to add requirements to NASA contracts. It will already be an intense and costly development effort. Anything you add will likely spiral into a testing effort you would regret.
Quote from: DigitalMan on 03/31/2020 09:30 pmQuote from: Robotbeat on 03/31/2020 07:17 pmImagine how dumb you’d look if you had one of these scenarios happen where the crew could’ve been rescued but they can’t. “I thought you said the port was androgynous?”“Well, see the thing is...”It isn't sane for the contractor to add requirements to NASA contracts. It will already be an intense and costly development effort. Anything you add will likely spiral into a testing effort you would regret.Right. NASA as the customer ought to insist on it.
Really, NASA ought to be insisting on androgynous capability at least for everything that needs to be active plus the lander. I means seriously, adding an extra docking adapter just to avoid making the lander or Orion androgynous! Insane.That’s just my personal opinion, though.
Quote from: Robotbeat on 03/31/2020 09:29 pmReally, NASA ought to be insisting on androgynous capability at least for everything that needs to be active plus the lander. I means seriously, adding an extra docking adapter just to avoid making the lander or Orion androgynous! Insane.That’s just my personal opinion, though.Well, just keep in mind that sending an adapter isn't much different from sending the Dragon XL, and you only do it once. Adding 100 lbm or more for a passive capability that may never be used, for every landing and ascent from the moon represents orders of magnitude more mass at liftoff. Or that much less capability to land on the moon.It's not quite this simple, but the docking drogue or cone on the Apollo Lunar Lander weighed 18-20 lbs. That's it. A modern docking system can weight several hundred pounds. Not quite apples to apples, but it gives a sense of scale.
Quote from: jarmumd on 03/31/2020 10:05 pmQuote from: Robotbeat on 03/31/2020 09:29 pmReally, NASA ought to be insisting on androgynous capability at least for everything that needs to be active plus the lander. I means seriously, adding an extra docking adapter just to avoid making the lander or Orion androgynous! Insane.That’s just my personal opinion, though.Well, just keep in mind that sending an adapter isn't much different from sending the Dragon XL, and you only do it once. Adding 100 lbm or more for a passive capability that may never be used, for every landing and ascent from the moon represents orders of magnitude more mass at liftoff. Or that much less capability to land on the moon.It's not quite this simple, but the docking drogue or cone on the Apollo Lunar Lander weighed 18-20 lbs. That's it. A modern docking system can weight several hundred pounds. Not quite apples to apples, but it gives a sense of scale.100lb or more for a passive capability? I find that hard to believe, but I’ll take your word for it.If we’re not using the advantages of a modern docking system, we should go back to a drogue and cone system and save even more weight.
100lb or more for a passive capability? I find that hard to believe, but I’ll take your word for it.If we’re not using the advantages of a modern docking system, we should go back to a drogue and cone system and save even more weight.
I'm getting really confused here. I thought that the difference between an active and a passive IDSS-compliant system is that the active system (of which NDS is an implementation) has the extendable soft-capture system, which has latches that engage with the passive system's petals. Then, once the soft-capture system retracts, active hooks on the active system engage with passive hooks on the passive system.
I can't see how a passive system would be heavier. Maybe some of the confusion is that the ISS's IDA is actually an adapter to make APAS IDSS-compliant? You wouldn't need that if you were to implement an IDSS passive system from scratch.
IDSS allows for active-active systems, doesn't it? So the real question is whether NDS has implemented active-active, or whether it's only able to be the active component of an active-passive system. Which is it?
There has to be a plan that makes sense here, because HLS without a Gateway is going to have to dock with Orion (an active NDS system), which would require HLS to be passive if NDS is only active-passive. But Orion is also going to have to dock with the Gateway, and if it's only active-passive, then the dock at the Gateway would have to be passive. But then HLS can't dock at the gateway.
So you have two options:1) You have separate active and passive docking ports on the Gateway, which is just dumb.
2) The HLS has to be able to work in both active-active mode (for docking with Orion) and active-passive mode (for docking with the GW)....How badly have I misunderstood this?
A problem with the active-active adapter for Gateway is it's going to compromise the rigidity and strength of the whole Gateway/visiting-vehicle stack. There's already a mass limit on Gateway-docking visiting vehicles, and having to use an adapter would theoretically reduce that allowable limit (longer moment arm for an already-long vehicle, additional flex which reduces the fundamental frequency and makes control harder, etc) besides adding more things that can fail and reducing inherent redundancy. I'm not sure that's captured by the requirements fully in a way that allows fair scoring, so that could be one area where the non-androgynous approach ends up penny-wise but pound-foolish.
Quote from: Robotbeat on 04/01/2020 12:15 amA problem with the active-active adapter for Gateway is it's going to compromise the rigidity and strength of the whole Gateway/visiting-vehicle stack. There's already a mass limit on Gateway-docking visiting vehicles, and having to use an adapter would theoretically reduce that allowable limit (longer moment arm for an already-long vehicle, additional flex which reduces the fundamental frequency and makes control harder, etc) besides adding more things that can fail and reducing inherent redundancy. I'm not sure that's captured by the requirements fully in a way that allows fair scoring, so that could be one area where the non-androgynous approach ends up penny-wise but pound-foolish.why wouldn't it stay attached to the gateway?
Quote from: jarmumd on 04/01/2020 12:26 amQuote from: Robotbeat on 04/01/2020 12:15 amA problem with the active-active adapter for Gateway is it's going to compromise the rigidity and strength of the whole Gateway/visiting-vehicle stack. There's already a mass limit on Gateway-docking visiting vehicles, and having to use an adapter would theoretically reduce that allowable limit (longer moment arm for an already-long vehicle, additional flex which reduces the fundamental frequency and makes control harder, etc) besides adding more things that can fail and reducing inherent redundancy. I'm not sure that's captured by the requirements fully in a way that allows fair scoring, so that could be one area where the non-androgynous approach ends up penny-wise but pound-foolish.why wouldn't it stay attached to the gateway?I didn’t say it wouldn’t. It still compromises the Gateway/VV stack.
Quote from: Robotbeat on 04/01/2020 12:28 amQuote from: jarmumd on 04/01/2020 12:26 amQuote from: Robotbeat on 04/01/2020 12:15 amA problem with the active-active adapter for Gateway is it's going to compromise the rigidity and strength of the whole Gateway/visiting-vehicle stack. There's already a mass limit on Gateway-docking visiting vehicles, and having to use an adapter would theoretically reduce that allowable limit (longer moment arm for an already-long vehicle, additional flex which reduces the fundamental frequency and makes control harder, etc) besides adding more things that can fail and reducing inherent redundancy. I'm not sure that's captured by the requirements fully in a way that allows fair scoring, so that could be one area where the non-androgynous approach ends up penny-wise but pound-foolish.why wouldn't it stay attached to the gateway?I didn’t say it wouldn’t. It still compromises the Gateway/VV stack.Wouldn't affect mass limit if it stays attachedbending moment ... nah... but you couldn't really know that. Just consider that docking is bounded by shuttle's off center CG, capsules don't put nearly the moment in.can't be lower than the ISS fundamental frequency, lolreducing redundancy more than a ISS made up of CBM's and other docking ports? See also frequency through all those ports.Just isn't an issue. You aren't wrong that all those things detract, just not as much as you think. And in the grand scheme, nothing in comparison to saving mass on a lander.