...- The SuperDraco engines will start only 800 m from the surface, while the capsule is doing 2.24 km/s. Deceleration will reach 7 g....
Quote from: charliem on 06/12/2012 10:20 pm...- The SuperDraco engines will start only 800 m from the surface, while the capsule is doing 2.24 km/s. Deceleration will reach 7 g....Actually, that's Mach 2.24, NOT 2.24 km/s! Huge difference! Easy mistake, though. Mach 2.24 is less than 1km/s.
the final terrain is not known and definitely not obstacle free,
Quote from: meekGee on 06/13/2012 12:09 am the final terrain is not known and definitely not obstacle free, curious,define "not known"...MRO has pretty good resolution..Apollo had worse resolution maps then what we have for mars..jb
The SuperDraco engines will start only 800 m from the surface, while the capsule is doing mach 2.24.
Quote from: charliem on 06/12/2012 10:20 pmThe SuperDraco engines will start only 800 m from the surface, while the capsule is doing mach 2.24.D***!
When converting Mach 2.4 to km/s, are those local Mach numbers?
Quote from: meekGee on 06/13/2012 12:09 amWhen converting Mach 2.4 to km/s, are those local Mach numbers?I think so.You can calculate the speed of sound from temperature and atmosphere composition. For the martian atmophere is: ss = sqr (247.42*T) (T in ēK, ss in m/s).At 3 km below MOLA the mean temperature is 245 ēK so the average speed of sound should be around 246 m/s (it swings quite a bit from day to night, summer to winter, and even with dust storms).So the Dragon capsule has to start its SuperDraco engines at ~550 m/s, 800 m before crashing, and decelerate at 7 g ... what a ride!!
So the Dragon capsule has to start its SuperDraco engines at ~550 m/s, 800 m before crashing, and decelerate at 7 g ... what a ride!!
Quote from: Jim on 06/12/2012 02:49 pmQuote from: go4mars on 06/12/2012 01:28 pmI don't know. But just about every type of factory occasionally has surplus inventor to deal with. Cars, toys, furniture...It sounds like this is the production model for SpaceX, though I'm not saying I know for sure either way.No, production is order based.In modern facilities, correct. But the production capacity is there. So the incremental cost to make one more article for internal consumption is low, especially when flex-scheduled to a time when orders are low.
Quote from: go4mars on 06/12/2012 01:28 pmI don't know. But just about every type of factory occasionally has surplus inventor to deal with. Cars, toys, furniture...It sounds like this is the production model for SpaceX, though I'm not saying I know for sure either way.No, production is order based.
I don't know. But just about every type of factory occasionally has surplus inventor to deal with. Cars, toys, furniture...It sounds like this is the production model for SpaceX, though I'm not saying I know for sure either way.
Boeing set up the Decatur factory for Delta IV to produce 48 Delta IV cores a year, so having such production capacity is nothing new.
Quote from: charliem on 06/13/2012 02:36 amSo the Dragon capsule has to start its SuperDraco engines at ~550 m/s, 800 m before crashing, and decelerate at 7 g ... what a ride!!Those numbers can't be right. I've rechecked them against the presentation and this time it's not my mistake.In one of the slides we can read: "* Performs a direct transition to powered flight at Mach 2.24 800 m above ground utilizing SuperDraco thrusters".That speed can't be vertical, because then a simple v=sqr(2.h.a) says that the minimum distance to brake from 550 m/s to zero at 7 gees is 2200 meters, so the only possibility that remains is a very very shallow descent.
Boeing set up the Decatur factory for Delta IV to produce 48 Delta IV cores a year, so having such production capacity is nothing new. The issue is lack of demand, which is what resulted in the ULA merger in the first place.
- As we know Dragon needs to prove a number of its [yet] theoretical capabilities, but my personal impression about the Nasa personnel doing the presentations is that they are non as skeptical as some over here ...