Quote from: OTV Booster on 07/25/2022 05:57 pmAs for 2001, Kubric and Clark had the docking ship aligned with and sharing the stations axis of rotation. A much easier problem, not to mention great visuals. That's pretty much what I'm visualizing, although (obviously) the depot is a lot smaller than the space station in the movie. You dock the nose of the starship with some sort of adaptor that facilitates leaving or receiving fuel. This probably works a lot better with a custom-designed depot rather than just repurposing a Starship, but you've still got to somehow make it work for the tanker vehicles and the ultimate "customer" vehicles.On the ground, I assume fueling is simply done through the tops of the tanks--just like filling up a car. I can see why people would be unenthusiastic about trying to do that from the side or the bottom. Although you certainly won't try to get the fuel out the same way, so it seems that any refueling plan is going to involve extra plumbing--for the tanker vehicles and the depot, anyway.
As for 2001, Kubric and Clark had the docking ship aligned with and sharing the stations axis of rotation. A much easier problem, not to mention great visuals.
Ahhh. I stand corrected. Was picturing side by side. I could be wrong but I think GSE fills the tanks from the bottom. No splash and the pressure head is the same if you're stuffing fluid into the bottom of a nearly full tank or stuffing it up a pipe to dump it in at the top.One reason I favor QD to QD transfer is that it adds exactly zero additional plumbing except for a gender bender. Give the depot a mirror image of a standard QD, and use a removable adapter on the GSE that services it and even this minor complexity stays on the ground.There was a time that 36 and 48 inch pipe wrenches were my companions. Plumbing is so conceptually simple and so very deceptive. It has soooo many failure modes, all wanting to jump out at you. Worse yet, sometimes they want to remain hidden and bedevil you. Anything that minimizes plumbing has my vote.
Why did SpaceX do away with the tail to tail fueling? A little thrust going toward the tanker would make the tanker empty into A Starship. This might still be done but on the side, Starship facing one way tanker the other but docked and emptying tanker.
You need the minimal gravity to ensure the tank outlet in covered by liquid, not for pumping.
Quote from: sebk on 07/27/2022 09:41 amYou need the minimal gravity to ensure the tank outlet in covered by liquid, not for pumping.Any idea how long it sloshes around before it settles? And I guess the microgravity accelerations means that fueling the target vehicle "upside down" isn't a problem, as compared to the issues with fueling a vehicle on Earth from the top of the tank.In the tail-to-tail configuration, I was wondering where the ullage engines would go. Or are they likely so small that it doesn't much matter?
Quote from: Greg Hullender on 07/27/2022 04:05 pmQuote from: sebk on 07/27/2022 09:41 amYou need the minimal gravity to ensure the tank outlet in covered by liquid, not for pumping.Any idea how long it sloshes around before it settles? And I guess the microgravity accelerations means that fueling the target vehicle "upside down" isn't a problem, as compared to the issues with fueling a vehicle on Earth from the top of the tank.In the tail-to-tail configuration, I was wondering where the ullage engines would go. Or are they likely so small that it doesn't much matter?It will take a few minutes. Generally check out how long restartable upper stages do pre burn venting/thrusting. And scale that up by a square root of height difference between typical upper stages ans Starship tankage. Or by 6th degree root of volume difference.
Separate question: Won't there also be a need to pump the pressurization gas from the recipient vehicle back into the donor? I haven't heard that talked about, but (in the spirit of the recent discussion), that's also extra plumbing.
Quote from: Greg Hullender on 07/27/2022 06:02 pmSeparate question: Won't there also be a need to pump the pressurization gas from the recipient vehicle back into the donor? I haven't heard that talked about, but (in the spirit of the recent discussion), that's also extra plumbing.just vent the receiving vehicle tank ( vent downward to add ullage thrust)
Quote from: daavery on 07/27/2022 08:53 pmQuote from: Greg Hullender on 07/27/2022 06:02 pmSeparate question: Won't there also be a need to pump the pressurization gas from the recipient vehicle back into the donor? I haven't heard that talked about, but (in the spirit of the recent discussion), that's also extra plumbing.just vent the receiving vehicle tank ( vent downward to add ullage thrust)You'd also have to pressurize the sending tank. It's much easier just to tie the two ullage spaces together with a simple line. It only has to be wide enough to move enough gas to offset the mass flow of the liquid. Maybe 1cm?
Quote from: TheRadicalModerate on 07/27/2022 11:05 pmQuote from: daavery on 07/27/2022 08:53 pmQuote from: Greg Hullender on 07/27/2022 06:02 pmSeparate question: Won't there also be a need to pump the pressurization gas from the recipient vehicle back into the donor? I haven't heard that talked about, but (in the spirit of the recent discussion), that's also extra plumbing.just vent the receiving vehicle tank ( vent downward to add ullage thrust)You'd also have to pressurize the sending tank. It's much easier just to tie the two ullage spaces together with a simple line. It only has to be wide enough to move enough gas to offset the mass flow of the liquid. Maybe 1cm?depending on your config all that will move the fluids is differential pressure - you want different ullage pressures in the 2 tanks
There's already autog press plumbing in the engine bay not far from the QD plate. Does anybody have that labeled QD pic handy? It might already be there.
100W? little low i think. Sir could u share your initial conditions. Or at least provide .txt or even spreadsheet Thanks.
Yup. Something is off, IMO.100W would be more likely good for for a 1t per hour rather than 150t per hour.Likely the calculation has some error or it assumed no friction/no viscosity case -- while especially at low flow rates it would actually dominate.
Quote from: OTV Booster on 07/28/2022 01:55 amThere's already autog press plumbing in the engine bay not far from the QD plate. Does anybody have that labeled QD pic handy? It might already be there.Female (ship-side) QD plate below. Labelled. And male (GSE-side) belower."Prepress" are the two you want.