Quote from: TrevorMonty on 04/07/2015 10:25 pm1) what is the weight saving of IVF?Weight savings through elimination of hydrazine, He, and most batteries have been suggested as 500 kg, but for longer duration missions with additional tankage and batteries thus no longer required, the savings should be even greater. I've seen suggestions that payload increases could amount to a ton on some missions. Better management of boiloff would contribute, too.Presumably the final figures will vary a lot with specific missions and further development of systems. It will be interesting to see how this translates to essentially free additional payload capability without any changes to the RL10 and the Centaur stage basic design.
1) what is the weight saving of IVF?
I love IVF, you've heard me rave about it before. I just have one complaint... what is taking ULA so long
They had a proposed mission for first flight. That customer essentially said: "not on my mission".I suspect this will be the response for most DoD/NASA missions....
This is why I wondered if it's possible to test smaller sections of IVF on other missions. Thrusters, battery pack, starting and stopping of the IC engine.
What makes the choice of piston internal combustion engine?Why not fuel cells or wankle or others?
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. The mission transition time is dependent on tank thermo, power level and other stuff but its usually after many days.
Is the twin engine setup shown in those simulations just notional or is the first flight actually going to use a twin engine Centaur? Would a single engine Centaur need only one ICE?
An aluminum block might be fine here. Even the Vega came with a 50,000 mile (~80,000 km) warranty.
Quote from: jongoff on 04/07/2015 09:48 pmThis engine runs so rich (GOX/GH2 has an amazingly wide flammability range) that I think it might not even need steel sleeves, though I might be wrong.Do you know what mixture ratio it's designed for?I believe Earth ICEs usually run pretty close to stoichiometric but they're kept cool by all the nitrogen in air. Even to match typical Earth ICE temperatures you'd need tons of unburned hydrogen so I'm skeptical of the no-steel-needed conjecture (but am not an engineer). It's certainly plausible that they might run it that fuel-rich so I'm not saying it's wrong, just I'd like to see more evidence before I'm convinced.
This engine runs so rich (GOX/GH2 has an amazingly wide flammability range) that I think it might not even need steel sleeves, though I might be wrong.