As an outsider it still baffles me how it was possible for Boeing to spend a long period of time divesting itself of its rocket building expertise into ULA and then for ULA not to be allowed to compete for SLS, for which it was the logical candidate by a very large margin.
IIRC a post on another thread mentioned Rolls Royce demonstrated furnace vacuum brazing, rather than individually welding the tubes, in the RZ20 of the late 1960's. This used a thin walled metal balloon to apply uniform pressure to the tubes to press them into a former. So the method of mfg for RL10's chambers has only been obsolete for the last 5 decades.
Quote from: john smith 19 on 05/09/2017 11:35 amAs an outsider it still baffles me how it was possible for Boeing to spend a long period of time divesting itself of its rocket building expertise into ULA and then for ULA not to be allowed to compete for SLS, for which it was the logical candidate by a very large margin.Why would Boeing want to share the SLS contract with LM via ULA?
Why would Boeing want to share the SLS contract with LM via ULA?
Are you implying that the RL10 has a hand brazed combustion chamber/nozzle? It was furnace brazed around a mandrel when I worked on them around 1990. I do agree with all your other comments about how it has way too much "handcrafting," especially the highly manual process by which all the tubes are formed.
I'm not exactly sure where to put this. I decided to put it in the VULCAN thread for lack of a better thread.With SpX regularly landing boosters like clockwork and launching National Security Payloads, Vulcan's whole business case is starting to look shaky; since SpX indirectly validated Blue Origin's own aspirations for New Glenn (the whole VTVL bit).Perhaps it's time for ULA to shift paradigms for the future from being a complete provider (boosters/upper stages/integration/launch services/initial orbital operations) to just being a standalone upper stage provider selling ACES to anyone who asks?If ULA has ACES ready in a couple years when Falcon Heavy is proven and New Glenn is just starting it's first flights; then they can corner the orbital propellant depot concept they've been touting with ACES.
Perhaps it's time for ULA to shift paradigms for the future from being a complete provider (boosters/upper stages/integration/launch services/initial orbital operations) to just being a standalone upper stage provider selling ACES to anyone who asks?
Upper stages are not Lego blocks.
Quote from: RyanC on 05/11/2017 09:04 pmPerhaps it's time for ULA to shift paradigms for the future from being a complete provider (boosters/upper stages/integration/launch services/initial orbital operations) to just being a standalone upper stage provider selling ACES to anyone who asks?A lot of the business case for ACES has to do with provision of in-space services after initial launch, including services involving multiple ACES spacecraft (the "distributed lift" stuff). It's hard to see how these services get sold if ULA is just a parts provider selling ACES to multiple vendors.It's not impossible for the same upper stage to ride different boosters (Centaur has certainly done that), but if you're looking to simplify ULA's development costs, it might make sense to turn this proposition around, and ask who might be interested in selling complete boosters to ULA. SpaceX doesn't seem really inclined, at the moment; Blue might be (they're already trying to sell engines to ULA), but the New Glenn booster will be way oversized for what ULA's planning, and given the more-Gradatim-than-Ferociter pace of their engineering, they might not want the distraction of building a cut-down version. (The engines they plan to sell are the same ones they'd have been building anyway.)
...I expect that BO will buy out the remaining IP and physical assets from ULA and what remains of ULA will become part of BO. ULA's experience in high energy upper stages and it's IP around ACES would be a good fit for BO's ambitions around Cislunar space and for the right price Bezo's wouldn't pass up the opportunity to acquire that technology.
Unless something has changed ULA is/was banned by the government from selling any parts or components not in a full vehicle. This is why they've always relied upon the parents to do their bidding for cargo, etc. The one exception on this is when it benefits the government and then they can sell things (i.e. ICPS for SLS).
1.ULA shall provide Launch Services on a non-discriminatory basis, which shall include, without limitation, the following: a.not entering into any exclusive Collaborative Agreement with any Space Vehicle Prime Contractor for Launch Services; b.not Discriminating in supporting the proposal of any Space Vehicle Prime Contractor; c.not Discriminating in providing Launch Services Information to all Space Vehicle Prime Contractors; d.not Discriminating regarding staffing decisions, resource allocation, or design decisions in connection with Launch Services to be offered or provided to any Space Vehicle Prime Contractor; e.not Discriminating in entering into Collaborative Agreements or other arrangements and not Discriminating as to any Space Vehicle Prime Contractors in the negotiations of such agreements and other arrangements. Such Collaborative Agreements shall not Discriminate in favor of Space Vehicle Business against any other Space Vehicle Prime Contractor on any basis, including, but not limited to, price, schedule, quality, data, personnel, investment (including, but not limited to, independent research and development), technology, innovations, design, and risk; f.not Discriminating among Space Vehicle Prime Contractors in making available for use in Launch Services any technologies developed by ULA under independent research and development funding, government-funded prime contract research and development activities or other funds expended by ULA but not provided by third parties, including LM and Boeing, or resulting from joint investment with a third party;
A lot of the business case for ACES has to do with provision of in-space services after initial launch, including services involving multiple ACES spacecraft (the "distributed lift" stuff). It's hard to see how these services get sold if ULA is just a parts provider selling ACES to multiple vendors.
Quote from: rst on 05/13/2017 03:31 amA lot of the business case for ACES has to do with provision of in-space services after initial launch, including services involving multiple ACES spacecraft (the "distributed lift" stuff). It's hard to see how these services get sold if ULA is just a parts provider selling ACES to multiple vendors.I was thinking, what if ACES ends up being a 40-45 tonne "wooden round" payload that's placed into a parking orbit by a variety of launch vehicle vendors?With the IVF system and associated chillers intended for ACES, it seems possible (at least to me) to create a LH2 system that can be loaded a few days beforehand, and then kept cold with minimal boiloff via external electrical power to run chillers.Then once in orbit, use ACES to perform whatever missions you want.
Quote from: john smith 19 on 05/02/2017 08:59 amQuote from: meekGee on 05/02/2017 05:41 amI'm going to look there again, but fuel cells also are subject to Carnot inefficiency, and have a lot of heat rejection.As for boil off, it really depends on how much power you need. An ICE uses a lot of gas volume and so if you're using more than the natural boil-off, you're only increasing the amount of boil off, and so your fuel is no longer free.If you only use so little fuel that you're below the boil off rate, maybe a small solar panel would be a better bet than a genset.Not to mention complexity... An internal combustion engine mechanism, and generator, and heat transfer - that's not simple nor cheap.Your comments suggest you have not read any of the IVF papers at all.Again, here are some of the IVF papers. ULA estimates that IVF will be one-third the combined weight of the legacy systems (power, pressurization, and attitude control) it replaces. With regards to mass flow rates, the second paper has the following quote:QuoteAccustomed as we are to atmospheric IC engines which pump nearly 80% inert gas, the mass flow rates of hydrogen and oxygen for the IVF ICE are surprisingly low. Approximately 2 kg/hr of hydrogen and half that amount of oxygen will be consumed at low power settings ranging up to 12.5 kg/hr at peak power.Integrated Vehicle Propulsion and Power System 2011Development Status of an Integrated Propulsion and Power System for Long Duration Cryogenic Spaceflight 2012Enabling Long Duration Spaceflight via an Integrated Vehicle Fluid System (AIAA Space 2016)
Quote from: meekGee on 05/02/2017 05:41 amI'm going to look there again, but fuel cells also are subject to Carnot inefficiency, and have a lot of heat rejection.As for boil off, it really depends on how much power you need. An ICE uses a lot of gas volume and so if you're using more than the natural boil-off, you're only increasing the amount of boil off, and so your fuel is no longer free.If you only use so little fuel that you're below the boil off rate, maybe a small solar panel would be a better bet than a genset.Not to mention complexity... An internal combustion engine mechanism, and generator, and heat transfer - that's not simple nor cheap.Your comments suggest you have not read any of the IVF papers at all.
I'm going to look there again, but fuel cells also are subject to Carnot inefficiency, and have a lot of heat rejection.As for boil off, it really depends on how much power you need. An ICE uses a lot of gas volume and so if you're using more than the natural boil-off, you're only increasing the amount of boil off, and so your fuel is no longer free.If you only use so little fuel that you're below the boil off rate, maybe a small solar panel would be a better bet than a genset.Not to mention complexity... An internal combustion engine mechanism, and generator, and heat transfer - that's not simple nor cheap.
Accustomed as we are to atmospheric IC engines which pump nearly 80% inert gas, the mass flow rates of hydrogen and oxygen for the IVF ICE are surprisingly low. Approximately 2 kg/hr of hydrogen and half that amount of oxygen will be consumed at low power settings ranging up to 12.5 kg/hr at peak power.
I've read these papers, and they are remarkably qualitative - almost no hard numbers.They are also self-contradictory - you can't argue that with insulation you've reduced boil-off to almost nothing, and then say you're going to generate 20 kWatts from the boil off.A pressurized stage has a steady state comprised of heat input, boil-off, and venting. As the pressure rises, boil-off slows down. If the structure of the stage cannot withstand the vapor pressure at the ambient temperature and temperature, you have to vent, but otherwise the pressure slows down the boil-off.Therefore, to the extent that you use more power than available through the venting, you're encouraging more boil off.The comments above about "perceived volume of gas used by the engine" are strawman argument.I was looking at the insane specific power of thin film PV arrays in space, at the insane advancements in battery power storage, and at the overwhelming simplicity of a PV-battery system when compared with an internal combustion and heat transfer system - and sorry - the ICE component of IVF is dated. It only made sense in comparison with PV and battery technologies of the 1990s.I understand IVF has other components, but the whole venture depended on a win-win-win scenario to justify the complexity, and I'm saying the ICE component is not on that list.Compare this to Tom's Muller description of how they are simplifying things to get some contrast.
Quote from: meekGee on 05/14/2017 08:20 pmI've read these papers, and they are remarkably qualitative - almost no hard numbers.They are also self-contradictory - you can't argue that with insulation you've reduced boil-off to almost nothing, and then say you're going to generate 20 kWatts from the boil off.A pressurized stage has a steady state comprised of heat input, boil-off, and venting. As the pressure rises, boil-off slows down. If the structure of the stage cannot withstand the vapor pressure at the ambient temperature and temperature, you have to vent, but otherwise the pressure slows down the boil-off.Therefore, to the extent that you use more power than available through the venting, you're encouraging more boil off.The comments above about "perceived volume of gas used by the engine" are strawman argument.I was looking at the insane specific power of thin film PV arrays in space, at the insane advancements in battery power storage, and at the overwhelming simplicity of a PV-battery system when compared with an internal combustion and heat transfer system - and sorry - the ICE component of IVF is dated. It only made sense in comparison with PV and battery technologies of the 1990s.I understand IVF has other components, but the whole venture depended on a win-win-win scenario to justify the complexity, and I'm saying the ICE component is not on that list.Compare this to Tom's Muller description of how they are simplifying things to get some contrast.So with your PV-battery powered ACES, what will you do with the boil-off gases, what will you use to pressurize the tanks, and what will you use for RCS thrusters? Do you still get unlimited restarts? Does this stage have a system to provide constant ullage thrust?
Boil off is always going to be issue with hydrolox stage no matter how good insulation.