What sort of igniter mechanisms are used, specifically for solid rockets, that work in a vacuum (i.e. the inertial upper stage)? And can any of these be applied to model rockets?
What sort of igniter mechanisms are used, specifically for solid rockets, that work in a vacuum (i.e. the inertial upper stage)? And can any of these be applied to model rockets?
All solid rocket motors, from the smallest estes to the Shuttles SRBs, use the same ignition mechanism, a detonator consisting of some sort of exploding bridge wire is used to ignite a combustible compound and the heat and flame from that ignites the propelant. The only difference is that the bigger motors use multiple stages of ignition to build up a big enough flame. On the shuttles SRBs, There are 3 other combustion steps between the NSI (Nasa standard initiator) and the ingnition of the main propelent. All of the steps happen so fast that they are, for all intents, instantanious. The system works just as well in a vacuum or in freefall as it does on the ground.
All solid rocket motors, from the smallest estes to the Shuttles SRBs, use the same ignition mechanism, [the] only difference is that the bigger motors use multiple stages of ignition to build up a big enough flame. On the shuttles SRBs, There are 3 other combustion steps between the NSI (Nasa standard initiator) and the ignition of the main propellant.
For Shuttle are there also multiple, independent firing chains for each SRB, making them fault-tolerant?
GEM-40/46 question.
I was looking at solid failures today (one actual failure, one separation failure) and was wondering how many GEM-40/46's had flown. It's about 1100 give or take, but was wondering if anyone knew of a good quick to use source for the actual numbers.
GEM-40/46 question.
I was looking at solid failures today (one actual failure, one separation failure) and was wondering how many GEM-40/46's had flown. It's about 1100 give or take, but was wondering if anyone knew of a good quick to use source for the actual numbers.
The best I can offer is a list of every Delta 2 flown. Only the 7000 series Deltas used GEM-40 and GEM-46 motors. To these you would need to add 27 GEM-46 motors flown on Delta 3 vehicles.
http://www.spacelaunchreport.com/delta2.html#logThe second digit in the model number tells how many solids were used.
- Ed Kyle
Thanks Ed, took the time to go through it... if I did the math right, it was actually a tad lower than I was estimating. 1071
15 73xx
18 74xx (which surprised me)
103 79xx (including H's)
3 8930
So 1071 have flown with only one solid failure, not too shabby.
btw. I think you have a typo for Dawn, I thought it was a 7925H, not a 7295H
Thanks Ed, took the time to go through it... if I did the math right, it was actually a tad lower than I was estimating. 1071
15 73xx
18 74xx (which surprised me)
103 79xx (including H's)
3 8930
So 1071 have flown with only one solid failure, not too shabby.
btw. I think you have a typo for Dawn, I thought it was a 7925H, not a 7295H
Thanks!
I just noticed that today (February 14, 2015) is the 26th anniversary of the first Delta 2 launch (a 6925).
- Ed Kyle
... if I did the math right, it was actually a tad lower than I was estimating. 1071
15 73xx
18 74xx (which surprised me)
103 79xx (including H's)
3 8930
So 1071 have flown with only one solid failure, not too shabby.
There were two GBI-BVs and one BV-Plus using the GEM-40VN, so three more for 1074. The second BV veered off course after 10 seconds - that's probably a control system failure, not the motor.