vda - 4/2/2007 8:40 AMWhy LM does not do it with Atlas V first stage? Look at the picture. Do I understand it right that they want to widen Centaur tank(s) first? Why not 1st stage first, then Centaur?
vda - 4/2/2007 8:40 AMTrying to understand ELV design better here..."Atlas growth" diagram: http://www.lockheedmartin.com/data/assets/12480.jpgGoing to wider tank diameter looks like rather simple operation - some tooling change at the factory and appropriate changes in engine attachment, but it doesn't look like difficult or costly thing to do. Especially when your upper stage is _already_ wider than first stage - you already pay "bigger cross-section" penalty.
edkyle99 - 4/2/2007 11:40 AMThe next obvious step would be to develop a wide-body Centaur - something that was already partly done with the old Titan IV Centaurs. The next step after that would be a bigger, more powerful booster. Etc. - Ed Kyle
bombay - 4/2/2007 12:05 PMQuoteedkyle99 - 4/2/2007 11:40 AMThe next obvious step would be to develop a wide-body Centaur - something that was already partly done with the old Titan IV Centaurs. The next step after that would be a bigger, more powerful booster. Etc. - Ed KyleWBC has been floating around in some form for the past 20 years but never got off of the ground. If WBC never came about under GD, Martin-Marrieta, or LM, all of whom had deep pockets to fund the development of a WBC, it's highly unlikely that it will come about any time soon from private sector development, that is, from ULA.
bombay - 4/2/2007 9:58 AMTo quite the contrary, tooling changes to increase diameter are extremely costly. You would for all intents and purposes have to acquire all new tooling and quite possibly a whole new building to accomadate growth in tank size. This amounts to untold $millions.You have to ask the question, why did Atlas V settle on 12.5 ft dia. versus going to 17 ft like the Delata IV? Existing Titan tooling and factory size pretty much dictated the choice to use a 12.5 ft. diameter Atlas V booster.
yinzer - 4/2/2007 8:34 PMI would like to request that Chris exercise a firm editorial hand on this thread to keep it Q&A rather than allowing it to degenerate into the mud-slinging that is becoming a permanent fixture of most threads involving EELVs.
yinzer - 4/2/2007 2:34 PMFor similar first stage performance, using kerosene instead of hydrogen as fuel means that you need a much smaller propellant volume. The 12.5 foot Atlas first stage is proving adequate for missions people are willing to pay money for; over half of the flights scheduled are in the 401 configuration alone, and there have been no further customers for the 551.If a 12.5 foot diameter booster is adequate for all likely payloads, and you have the tooling for it, why go for something bigger?
bombay - 4/2/2007 4:55 PMQuoteedkyle99 - 4/2/2007 11:40 AMThe next obvious step would be to develop a wide-body Centaur - something that was already partly done with the old Titan IV Centaurs. The next step after that would be a bigger, more powerful booster. Etc. - Ed KyleAnother thing that comes to mind is the Titan IV Centaur, though wider in diameter than the Atlas Centaur was of the stainless balloon variety.No doubt if a WBC were to be developed today, it would be of the structurally stable variety. The common bulkhead methodology unique to the stainless balloon would not/could not be used. I would expect mass ratio to take a hit as well.
bombay - 3/2/2007 6:58 PMTo quite the contrary, tooling changes to increase diameter are extremely costly.
Jim - 4/2/2007 4:12 PMQuotebombay - 4/2/2007 4:55 PMQuoteedkyle99 - 4/2/2007 11:40 AMThe next obvious step would be to develop a wide-body Centaur - something that was already partly done with the old Titan IV Centaurs. The next step after that would be a bigger, more powerful booster. Etc. - Ed KyleAnother thing that comes to mind is the Titan IV Centaur, though wider in diameter than the Atlas Centaur was of the stainless balloon variety.No doubt if a WBC were to be developed today, it would be of the structurally stable variety. The common bulkhead methodology unique to the stainless balloon would not/could not be used. I would expect mass ratio to take a hit as well.Look at the documents. It uses the same common bulkhead design. And it states that is not structural stable but can still maintaint mass ratio of the shuttle centaur
bombay - 4/2/2007 9:58 AMYou have to ask the question, why did Atlas V settle on 12.5 ft dia. versus going to 17 ft like the Delata IV? Existing Titan tooling and factory size pretty much dictated the choice to use a 12.5 ft. diameter Atlas V booster.
yinzer - 4/2/2007 4:52 PMQuotebombay - 4/2/2007 9:58 AMYou have to ask the question, why did Atlas V settle on 12.5 ft dia. versus going to 17 ft like the Delata IV? Existing Titan tooling and factory size pretty much dictated the choice to use a 12.5 ft. diameter Atlas V booster.I'm curious as to how existing Titan tooling lead to the 12.5 ft diameter Atlas V booster. All Titan stages (except the Centaur G, which doesn't apply in this case) were 10 ft diameter.
bombay - 4/2/2007 6:05 PMQuoteyinzer - 4/2/2007 4:52 PMQuotebombay - 4/2/2007 9:58 AMYou have to ask the question, why did Atlas V settle on 12.5 ft dia. versus going to 17 ft like the Delata IV? Existing Titan tooling and factory size pretty much dictated the choice to use a 12.5 ft. diameter Atlas V booster.I'm curious as to how existing Titan tooling lead to the 12.5 ft diameter Atlas V booster. All Titan stages (except the Centaur G, which doesn't apply in this case) were 10 ft diameter.Titan IV tooling could accomodate up to 12.5 ft diameter without significant remods.