Rocket alligators maybe?
It's of course possible that the pad 39a flame trench isn't rated for that abuse, but if I remember right they did make modifications to it, so it could be. What better way of putting the pad infrastructure through its paces than a full duration burn.
Hold downs are more of a consideration. Launch pads typically don't deal with an almost empty stage at full thrust.
Quote from: CorvusCorax on 04/20/2016 03:37 pmIt's of course possible that the pad 39a flame trench isn't rated for that abuse, but if I remember right they did make modifications to it, so it could be. What better way of putting the pad infrastructure through its paces than a full duration burn.Hold downs are more of a consideration. Launch pads typically don't deal with an almost empty stage at full thrust.
Quote from: Jim on 04/20/2016 04:47 pmHold downs are more of a consideration. Launch pads typically don't deal with an almost empty stage at full thrust.So maybe they're thinking 10 static fires of 18s in duration each, or whatever. Similar total burn time, less head load on everything, and the rocket would still be relatively full after 18s of burn.
Would the hold-down mechanisms be significantly different than at McGregor?
You're assuming they're going to top it off, which is possible, but even if they do you're still missing a second stage worth of fuel and a payload. Some quick and dirty calculations suggest that without the second stage and payload, you're adding in the realm of 50% to the strain on those hold downs. If it's a mostly empty stage, we're talking anywhere from 300% on up to the increase in strain, each hold-down taking up to 325,000 lbf of tension, over 162 tons a piece. Even if the hold-downs could take that kind of strain, I have to wonder what the attachment points on the thrust plate are rated for.EDIT: I realize the thrust plate does take the full force of the engines and weight of the rocket, I'm just wondering how much the load paths are affected.
Well, considering they still regularly do full thrust full duration burns at Mc Gregor,
I guess it is possible SpaceX is planning on putting a second stage slated for whatever flight the reflown booster will be assigned to for the series of "ten" static fires, but that seems less likely to me.
and keep it fed
Quote from: Meltro on 04/20/2016 06:30 pmand keep it fed That requires re-engineering
I'm not sure about needing a weighted mass simulator to test from the pad but I could see them bringing in a dummy upper stage for one simple reason. If the rocket has an upper stage on it they can use the transporter-erector to move the rocket to and back from the pad instead of having to use a crane.
Quote from: StuffOfInterest on 04/20/2016 06:39 pmI'm not sure about needing a weighted mass simulator to test from the pad but I could see them bringing in a dummy upper stage for one simple reason. If the rocket has an upper stage on it they can use the transporter-erector to move the rocket to and back from the pad instead of having to use a crane.Thought about that, but the dummy would need to weigh as much as a loaded stage, and I think the TE moves the rocket dry.
Quote from: Jim on 04/20/2016 06:36 pmQuote from: Meltro on 04/20/2016 06:30 pmand keep it fed That requires re-engineeringFuel pumps don't have enough flow to keep it supplied? I know the fueling process takes a while, but I'd assumed they had a bit of leeway on how fast they pumped it in.Quote from: StuffOfInterest on 04/20/2016 06:39 pmI'm not sure about needing a weighted mass simulator to test from the pad but I could see them bringing in a dummy upper stage for one simple reason. If the rocket has an upper stage on it they can use the transporter-erector to move the rocket to and back from the pad instead of having to use a crane.Thought about that, but the dummy would need to weigh as much as a loaded stage, and I think the TE moves the rocket dry.