Quote from: muomega0 on 04/06/2015 01:36 pmAnd ULA chose the to work on IVF rather than launch costs. Sarcasm hat off, but IVF promises to cost less, reduce upper stage complexity, and improve the performance of the upper stages. It reduces costs, not all of them, but a small portion in it's own right.
And ULA chose the to work on IVF rather than launch costs.
Quote from: muomega0 on 04/06/2015 01:36 pmI must have missed something...what were the specific benefits for a BEO architecture?That is not a primary driver
I must have missed something...what were the specific benefits for a BEO architecture?
IVF does not get rid of GHe,
Of course! the space policy of keeping everything separate is still in place.
Quote from: TrevorMonty on 04/06/2015 03:12 amThanks Donald for patent. Very informative, the number of benefits is huge. Nice to see electrical system will benefit from hybrid car technology ie combination start/generator, batteries.I must have missed something...what were the specific benefits for a BEO architecture? Launch hydrogen and oxygen at 225M/20mT and burning it with a piston engineAnd ULA chose the to work on IVF rather than launch costs.
Thanks Donald for patent. Very informative, the number of benefits is huge. Nice to see electrical system will benefit from hybrid car technology ie combination start/generator, batteries.
It isn't the battery, it is helium. The start pulse has little on effect on the batteries.
clearly 'less cost' depends on 220M vs 20M per flight and the kg of propellant burned for power....lots of hand waving in this entire thread.The problem statement was to get rid of GHe, Hydrazine, large Batteries & high pressures; enable depot based space transport.
IVF does not get rid of GHe, but does get rid of large batteries, but still needs small batteries--not a bad start.
If your transfer stage does not include a power source, then perhaps the IVF concept is 'better'.If your transfer stage/depot includes a power source, burning hydrogen is not efficient nor cost effective unless the mission duration is a few days to a week or so.
At some point lifetime/mission complexity increase begins to require GNC "upgrade" beyond existing profiles, to put these benefits to effective use?Again, only, solely addressing launch service benefits to existing/near term customers.
Quote from: Jim on 04/05/2015 12:24 pmIt isn't the battery, it is helium. The start pulse has little on effect on the batteries.True, although I'm not sure that was actually known before the analysis for IVF started.
Basically, IVF takes a major liability of liquid hydrogen, and turns it into an asset. The hydrogen and oxygen are going to boil off and be lost anyway, so use it for ullage, attitude control, pressurization and electric power. Eliminate the hydrazine, high pressure helium and most of the batteries, which get heavy on extended duration flights. IVF can increase payload by upwards of a ton, and increase flight duration to days instead of hours.
Quote from: Damon Hill on 04/04/2015 11:30 amBasically, IVF takes a major liability of liquid hydrogen, and turns it into an asset. The hydrogen and oxygen are going to boil off and be lost anyway, so use it for ullage, attitude control, pressurization and electric power. Eliminate the hydrazine, high pressure helium and most of the batteries, which get heavy on extended duration flights. IVF can increase payload by upwards of a ton, and increase flight duration to days instead of hours.But its a giant piston engine with a bunch of steel in it. How is that lighter than anything else? How does using the IVF avoid having to use ullage thrusters? Still not understanding.Why was hydrogen fuel cell chosen against?
But its a giant piston engine with a bunch of steel in it. How is that lighter than anything else? How does using the IVF avoid having to use ullage thrusters? Still not understanding.Why was hydrogen fuel cell chosen against?
Quote from: muomega0 on 04/06/2015 04:27 pmclearly 'less cost' depends on 220M vs 20M per flight and the kg of propellant burned for power....lots of hand waving in this entire thread.The problem statement was to get rid of GHe, Hydrazine, large Batteries & high pressures; enable depot based space transport. Where did you get that idea?
GoalsSlash costs by designing in the best possible system reliability - Get rid of GHe, Hydrazine, large Batteries & high pressures - Simple, commercial designs and materials, no toxic/hazardous operations Amplify performance & mission capability – Eliminate restrictions to flight duration except by main vehicle propellantsSupport all likely future transport architectures - Enable depot based space transport
QuoteIVF does not get rid of GHe, but does get rid of large batteries, but still needs small batteries--not a bad start.I'm not sure how much you understand about how IVF works but it replaces the GHe to pressurize the tanks with warm GO2 and GH2 heated by the IC engine. while for most applications the heat from the engines cooling system is a waste product on IVF it's one of the main products of the system. The battery is much smaller than the current battery boxes and runs around 300-400V, in keeping with Hybrid vehicle technology, rather than aerospace practice.
OTOH if you want a low cost (IE minimal development cost) to deliver a depot architecture at short notice IVF has benefits.QuoteSo the goal was to eliminate restrictions to flight duration and enable depots for future architectures per the ULA documents. How is it doing?Quote from: Damon Hill on 04/06/2015 08:24 pmIVF as envisioned in the near term is not all things to all possible missions, nor should it be. Missions that last from a few hours to a few days don't need the near-heroic measures of advanced insulation and thermal control, and active refrigeration. What IVF would accomplish is to >save money< by eliminating systems, saving weight and increasing payloads substantially as a direct result for any mission but even more so for the longer ones, by using a resource that was otherwise being wasted. The returns are diminishing as mission time is extended beyond perhaps a week or so. Other technologies have to be brought into play to conserve the cryogenic propellants. Those missions haven't been possible up to now anyway, so what's the complaint?
So the goal was to eliminate restrictions to flight duration and enable depots for future architectures per the ULA documents. How is it doing?Quote from: Damon Hill on 04/06/2015 08:24 pmIVF as envisioned in the near term is not all things to all possible missions, nor should it be. Missions that last from a few hours to a few days don't need the near-heroic measures of advanced insulation and thermal control, and active refrigeration. What IVF would accomplish is to >save money< by eliminating systems, saving weight and increasing payloads substantially as a direct result for any mission but even more so for the longer ones, by using a resource that was otherwise being wasted. The returns are diminishing as mission time is extended beyond perhaps a week or so. Other technologies have to be brought into play to conserve the cryogenic propellants. Those missions haven't been possible up to now anyway, so what's the complaint?
IVF as envisioned in the near term is not all things to all possible missions, nor should it be. Missions that last from a few hours to a few days don't need the near-heroic measures of advanced insulation and thermal control, and active refrigeration. What IVF would accomplish is to >save money< by eliminating systems, saving weight and increasing payloads substantially as a direct result for any mission but even more so for the longer ones, by using a resource that was otherwise being wasted. The returns are diminishing as mission time is extended beyond perhaps a week or so. Other technologies have to be brought into play to conserve the cryogenic propellants. Those missions haven't been possible up to now anyway, so what's the complaint?
There are a couple anchor concepts that make IVF attractive. The first is that the wall-conduction waste heat from the ICE is put to work effectively doubling the "efficiency" of the system. This is rare since nearly all heat engines cannot do this and you end up with that depressing Carnot efficiency thing. The ullage gases are not just a fuel- they are a repository for energy that we charge and discharge just like a battery. The exhaust energy is put to work too settling the vehicle. When you combine these efficient uses with more or less free reactants it's hard to beat. The main vehicle tanks are by far the most effective (non-nuclear) way to store energy yet conceived. IVF works beautifully in concert with fuel cells and solar electric systems. You let those systems handle long-duration low-level power demands and turn IVF on when you need to do heavy lifting. This enables them to be compact and light since they don't have to handle peak loads. You can even eliminate dedicated controllers and power processing units which are major elements in the cost of those systems.
When its fielded it will seem obvious and boring.
Adding warm G02 and GH2 to tanks is not desireable is one is seeking low to zero boiloff. Yes, GHe is eliminated per the documents.The 'complaint' is that the system states all these grand goals, then compromises the IVF system architecture to meet a short term goal.
Quote from: muomega0 on 04/07/2015 04:09 pmAdding warm G02 and GH2 to tanks is not desireable is one is seeking low to zero boiloff. Yes, GHe is eliminated per the documents.The 'complaint' is that the system states all these grand goals, then compromises the IVF system architecture to meet a short term goal.1. warm G02 and GH2 is only added during engine operation where boil off is not a concern.2. Pray tell, how is the IVF system architecture "compromised"?
IVF is highly derivative of systems that have been used over the years and is not that scary of a leap- it is straightforward evolutionary thinking. It takes concepts from Saturn, Shuttle, Centaur, Delta, 787, a century of automotive ICE design and the Prius and combines them in a new synthesis. The architecture has shifted nine times since its inception as we learned what works and what doesn't. A lot of it is how to make something efficient that is also low cost. When its fielded it will seem obvious and boring.
1. So this is not part of the overall future architectures...understood. Why not cool the gas?2. The pumps are mechanically driven. So how are the pumps powered by Electric/Nuclear propulsion?