How do you confirm ignition in the combustion chamber of a rocket?
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Is ignition confirmed using a temperature sensor, pressure sensor or another device?
propulsion engine-design combustion ignition
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up vote
17
down vote
favorite
Is ignition confirmed using a temperature sensor, pressure sensor or another device?
propulsion engine-design combustion ignition
New contributor
add a comment |
up vote
17
down vote
favorite
up vote
17
down vote
favorite
Is ignition confirmed using a temperature sensor, pressure sensor or another device?
propulsion engine-design combustion ignition
New contributor
Is ignition confirmed using a temperature sensor, pressure sensor or another device?
propulsion engine-design combustion ignition
propulsion engine-design combustion ignition
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New contributor
edited Nov 7 at 16:09
Organic Marble
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asked Nov 7 at 11:35
EdwardJ
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2 Answers
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oldest
votes
up vote
16
down vote
For the Space Shuttle Main Engine, four checks were done to set the "Ignition Confirmed" condition.
- The High Pressure Fuel Turbopump shaft speed was checked against a minimum limit.
- The Main Combustion Chamber pressure was checked twice, once against a minimum limit, and once to ensure it was between an upper and lower bound.
- The Antiflood Valve was checked to ensure that it was open.
The Antiflood Valve was a pressure-operated poppet valve that, when open, allowed liquid oxygen to flow into the SSME heat exchanger and then on to the LOX tank in the External Tank.
source
Lots of other parameters were checked continuously throughout engine operation and could shut the system down if limits were exceeded; these were just the ones that set Ignition Confirmed.
The chart says MCC PC, 290 psia at 1700 ms and 610 to 1,000 psia at 2400 ms. Are those readings from a pressure transducer connected directly to the combustion chamber itself, exposed to the burning fuel's heat and pressure, or some indirect measurement?
– uhoh
Nov 7 at 17:03
1
I think this answers that: space.stackexchange.com/questions/28134/…
– Organic Marble
Nov 7 at 17:16
1
perfectly, thanks!
– uhoh
Nov 7 at 17:32
Its really weird reading that the are 4 checks, but then seeing only 3 numbers
– Ferrybig
Nov 8 at 7:39
@Ferrybig I don't understand your comment.
– Organic Marble
Nov 8 at 11:48
|
show 1 more comment
up vote
5
down vote
How do you confirm ignition in the combustion chamber of a rocket?
Sometimes, you don't. Pressure sensors, flow sensors, and such are yet another device that can fail. Moreover, what if nothing can be done / needs to be done if ignition fails to occur? In the case of the Shuttle (Organic Marble's answer), all three main engines were needed for launch. Something could be done and had to be done in the case of failed ignition: All engines needed to be shut down and the ignition of the solid rocket boosters needed to be prevented. The Shuttle used a number of sensors, pressure sensors and flow sensors, to determine whether launch needed to be aborted in the 6.6 seconds between the command to light the main engines and liftoff. This Redundant Set Launch Sequencer (RSLS) abort happened five times, at least once because of a failed sensor rather than a true problem.
Consider instead an uncrewed vehicle that has been launched and released from the launch vehicle. Suppose the vehicle has a zero fault tolerant main engine and a non-redundant set of zero fault tolerant attitude thrusters. The engine and attitude thrusters either work or they don't. Nothing can be done, and nothing needs to be done with if an engine fails. Vehicles such as these typically do not have sensors that detect ignition.
Another way to avoid those very expensive and failure-prone sensors is to make the navigation sensors such as accelerometers and rate gyros serve dual purpose as thruster failure detection devices. The point of using thrusters is to change the vehicle's translational or angular velocity; thruster failure should, in theory, be detectable via the navigation sensors. NASA used this approach for Mini AERCam, Synchronized Position Hold Engage and Reorient Experimental Satellite (SPHERES), and for X-38. Mini AERCam and SPHERES used cold gas thrusters; all that's needed are flow sensors. These vehicles are so small that a little puff of cold gas makes the vehicle respond very quickly. This responsiveness made Mini AERCam and SPHERES thruster failures rather easy to detect via the navigation sensors.
X38 on the other hand was a bit balky and responded rather slowly to thruster firings. This made X-38 thruster failures rather difficult to detect via the navigation sensors. Using navigation sensors to detect thruster failures suffered a noise to signal problem. Statistical techniques were needed to gradually let the navigational signal from a thruster failure gradually rise above the noise inherent in the navigation sensors.
But sensors used for telemetry data may be used for ignition detection too.
– Uwe
Nov 7 at 19:58
@Uwe - It doesn't matter whether the failure detection is an onboard or ground control function. The data will come from various onboard sensors, and that's what the question is asking about.
– David Hammen
Nov 7 at 22:02
add a comment |
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
16
down vote
For the Space Shuttle Main Engine, four checks were done to set the "Ignition Confirmed" condition.
- The High Pressure Fuel Turbopump shaft speed was checked against a minimum limit.
- The Main Combustion Chamber pressure was checked twice, once against a minimum limit, and once to ensure it was between an upper and lower bound.
- The Antiflood Valve was checked to ensure that it was open.
The Antiflood Valve was a pressure-operated poppet valve that, when open, allowed liquid oxygen to flow into the SSME heat exchanger and then on to the LOX tank in the External Tank.
source
Lots of other parameters were checked continuously throughout engine operation and could shut the system down if limits were exceeded; these were just the ones that set Ignition Confirmed.
The chart says MCC PC, 290 psia at 1700 ms and 610 to 1,000 psia at 2400 ms. Are those readings from a pressure transducer connected directly to the combustion chamber itself, exposed to the burning fuel's heat and pressure, or some indirect measurement?
– uhoh
Nov 7 at 17:03
1
I think this answers that: space.stackexchange.com/questions/28134/…
– Organic Marble
Nov 7 at 17:16
1
perfectly, thanks!
– uhoh
Nov 7 at 17:32
Its really weird reading that the are 4 checks, but then seeing only 3 numbers
– Ferrybig
Nov 8 at 7:39
@Ferrybig I don't understand your comment.
– Organic Marble
Nov 8 at 11:48
|
show 1 more comment
up vote
16
down vote
For the Space Shuttle Main Engine, four checks were done to set the "Ignition Confirmed" condition.
- The High Pressure Fuel Turbopump shaft speed was checked against a minimum limit.
- The Main Combustion Chamber pressure was checked twice, once against a minimum limit, and once to ensure it was between an upper and lower bound.
- The Antiflood Valve was checked to ensure that it was open.
The Antiflood Valve was a pressure-operated poppet valve that, when open, allowed liquid oxygen to flow into the SSME heat exchanger and then on to the LOX tank in the External Tank.
source
Lots of other parameters were checked continuously throughout engine operation and could shut the system down if limits were exceeded; these were just the ones that set Ignition Confirmed.
The chart says MCC PC, 290 psia at 1700 ms and 610 to 1,000 psia at 2400 ms. Are those readings from a pressure transducer connected directly to the combustion chamber itself, exposed to the burning fuel's heat and pressure, or some indirect measurement?
– uhoh
Nov 7 at 17:03
1
I think this answers that: space.stackexchange.com/questions/28134/…
– Organic Marble
Nov 7 at 17:16
1
perfectly, thanks!
– uhoh
Nov 7 at 17:32
Its really weird reading that the are 4 checks, but then seeing only 3 numbers
– Ferrybig
Nov 8 at 7:39
@Ferrybig I don't understand your comment.
– Organic Marble
Nov 8 at 11:48
|
show 1 more comment
up vote
16
down vote
up vote
16
down vote
For the Space Shuttle Main Engine, four checks were done to set the "Ignition Confirmed" condition.
- The High Pressure Fuel Turbopump shaft speed was checked against a minimum limit.
- The Main Combustion Chamber pressure was checked twice, once against a minimum limit, and once to ensure it was between an upper and lower bound.
- The Antiflood Valve was checked to ensure that it was open.
The Antiflood Valve was a pressure-operated poppet valve that, when open, allowed liquid oxygen to flow into the SSME heat exchanger and then on to the LOX tank in the External Tank.
source
Lots of other parameters were checked continuously throughout engine operation and could shut the system down if limits were exceeded; these were just the ones that set Ignition Confirmed.
For the Space Shuttle Main Engine, four checks were done to set the "Ignition Confirmed" condition.
- The High Pressure Fuel Turbopump shaft speed was checked against a minimum limit.
- The Main Combustion Chamber pressure was checked twice, once against a minimum limit, and once to ensure it was between an upper and lower bound.
- The Antiflood Valve was checked to ensure that it was open.
The Antiflood Valve was a pressure-operated poppet valve that, when open, allowed liquid oxygen to flow into the SSME heat exchanger and then on to the LOX tank in the External Tank.
source
Lots of other parameters were checked continuously throughout engine operation and could shut the system down if limits were exceeded; these were just the ones that set Ignition Confirmed.
answered Nov 7 at 16:05
Organic Marble
51.4k3135217
51.4k3135217
The chart says MCC PC, 290 psia at 1700 ms and 610 to 1,000 psia at 2400 ms. Are those readings from a pressure transducer connected directly to the combustion chamber itself, exposed to the burning fuel's heat and pressure, or some indirect measurement?
– uhoh
Nov 7 at 17:03
1
I think this answers that: space.stackexchange.com/questions/28134/…
– Organic Marble
Nov 7 at 17:16
1
perfectly, thanks!
– uhoh
Nov 7 at 17:32
Its really weird reading that the are 4 checks, but then seeing only 3 numbers
– Ferrybig
Nov 8 at 7:39
@Ferrybig I don't understand your comment.
– Organic Marble
Nov 8 at 11:48
|
show 1 more comment
The chart says MCC PC, 290 psia at 1700 ms and 610 to 1,000 psia at 2400 ms. Are those readings from a pressure transducer connected directly to the combustion chamber itself, exposed to the burning fuel's heat and pressure, or some indirect measurement?
– uhoh
Nov 7 at 17:03
1
I think this answers that: space.stackexchange.com/questions/28134/…
– Organic Marble
Nov 7 at 17:16
1
perfectly, thanks!
– uhoh
Nov 7 at 17:32
Its really weird reading that the are 4 checks, but then seeing only 3 numbers
– Ferrybig
Nov 8 at 7:39
@Ferrybig I don't understand your comment.
– Organic Marble
Nov 8 at 11:48
The chart says MCC PC, 290 psia at 1700 ms and 610 to 1,000 psia at 2400 ms. Are those readings from a pressure transducer connected directly to the combustion chamber itself, exposed to the burning fuel's heat and pressure, or some indirect measurement?
– uhoh
Nov 7 at 17:03
The chart says MCC PC, 290 psia at 1700 ms and 610 to 1,000 psia at 2400 ms. Are those readings from a pressure transducer connected directly to the combustion chamber itself, exposed to the burning fuel's heat and pressure, or some indirect measurement?
– uhoh
Nov 7 at 17:03
1
1
I think this answers that: space.stackexchange.com/questions/28134/…
– Organic Marble
Nov 7 at 17:16
I think this answers that: space.stackexchange.com/questions/28134/…
– Organic Marble
Nov 7 at 17:16
1
1
perfectly, thanks!
– uhoh
Nov 7 at 17:32
perfectly, thanks!
– uhoh
Nov 7 at 17:32
Its really weird reading that the are 4 checks, but then seeing only 3 numbers
– Ferrybig
Nov 8 at 7:39
Its really weird reading that the are 4 checks, but then seeing only 3 numbers
– Ferrybig
Nov 8 at 7:39
@Ferrybig I don't understand your comment.
– Organic Marble
Nov 8 at 11:48
@Ferrybig I don't understand your comment.
– Organic Marble
Nov 8 at 11:48
|
show 1 more comment
up vote
5
down vote
How do you confirm ignition in the combustion chamber of a rocket?
Sometimes, you don't. Pressure sensors, flow sensors, and such are yet another device that can fail. Moreover, what if nothing can be done / needs to be done if ignition fails to occur? In the case of the Shuttle (Organic Marble's answer), all three main engines were needed for launch. Something could be done and had to be done in the case of failed ignition: All engines needed to be shut down and the ignition of the solid rocket boosters needed to be prevented. The Shuttle used a number of sensors, pressure sensors and flow sensors, to determine whether launch needed to be aborted in the 6.6 seconds between the command to light the main engines and liftoff. This Redundant Set Launch Sequencer (RSLS) abort happened five times, at least once because of a failed sensor rather than a true problem.
Consider instead an uncrewed vehicle that has been launched and released from the launch vehicle. Suppose the vehicle has a zero fault tolerant main engine and a non-redundant set of zero fault tolerant attitude thrusters. The engine and attitude thrusters either work or they don't. Nothing can be done, and nothing needs to be done with if an engine fails. Vehicles such as these typically do not have sensors that detect ignition.
Another way to avoid those very expensive and failure-prone sensors is to make the navigation sensors such as accelerometers and rate gyros serve dual purpose as thruster failure detection devices. The point of using thrusters is to change the vehicle's translational or angular velocity; thruster failure should, in theory, be detectable via the navigation sensors. NASA used this approach for Mini AERCam, Synchronized Position Hold Engage and Reorient Experimental Satellite (SPHERES), and for X-38. Mini AERCam and SPHERES used cold gas thrusters; all that's needed are flow sensors. These vehicles are so small that a little puff of cold gas makes the vehicle respond very quickly. This responsiveness made Mini AERCam and SPHERES thruster failures rather easy to detect via the navigation sensors.
X38 on the other hand was a bit balky and responded rather slowly to thruster firings. This made X-38 thruster failures rather difficult to detect via the navigation sensors. Using navigation sensors to detect thruster failures suffered a noise to signal problem. Statistical techniques were needed to gradually let the navigational signal from a thruster failure gradually rise above the noise inherent in the navigation sensors.
But sensors used for telemetry data may be used for ignition detection too.
– Uwe
Nov 7 at 19:58
@Uwe - It doesn't matter whether the failure detection is an onboard or ground control function. The data will come from various onboard sensors, and that's what the question is asking about.
– David Hammen
Nov 7 at 22:02
add a comment |
up vote
5
down vote
How do you confirm ignition in the combustion chamber of a rocket?
Sometimes, you don't. Pressure sensors, flow sensors, and such are yet another device that can fail. Moreover, what if nothing can be done / needs to be done if ignition fails to occur? In the case of the Shuttle (Organic Marble's answer), all three main engines were needed for launch. Something could be done and had to be done in the case of failed ignition: All engines needed to be shut down and the ignition of the solid rocket boosters needed to be prevented. The Shuttle used a number of sensors, pressure sensors and flow sensors, to determine whether launch needed to be aborted in the 6.6 seconds between the command to light the main engines and liftoff. This Redundant Set Launch Sequencer (RSLS) abort happened five times, at least once because of a failed sensor rather than a true problem.
Consider instead an uncrewed vehicle that has been launched and released from the launch vehicle. Suppose the vehicle has a zero fault tolerant main engine and a non-redundant set of zero fault tolerant attitude thrusters. The engine and attitude thrusters either work or they don't. Nothing can be done, and nothing needs to be done with if an engine fails. Vehicles such as these typically do not have sensors that detect ignition.
Another way to avoid those very expensive and failure-prone sensors is to make the navigation sensors such as accelerometers and rate gyros serve dual purpose as thruster failure detection devices. The point of using thrusters is to change the vehicle's translational or angular velocity; thruster failure should, in theory, be detectable via the navigation sensors. NASA used this approach for Mini AERCam, Synchronized Position Hold Engage and Reorient Experimental Satellite (SPHERES), and for X-38. Mini AERCam and SPHERES used cold gas thrusters; all that's needed are flow sensors. These vehicles are so small that a little puff of cold gas makes the vehicle respond very quickly. This responsiveness made Mini AERCam and SPHERES thruster failures rather easy to detect via the navigation sensors.
X38 on the other hand was a bit balky and responded rather slowly to thruster firings. This made X-38 thruster failures rather difficult to detect via the navigation sensors. Using navigation sensors to detect thruster failures suffered a noise to signal problem. Statistical techniques were needed to gradually let the navigational signal from a thruster failure gradually rise above the noise inherent in the navigation sensors.
But sensors used for telemetry data may be used for ignition detection too.
– Uwe
Nov 7 at 19:58
@Uwe - It doesn't matter whether the failure detection is an onboard or ground control function. The data will come from various onboard sensors, and that's what the question is asking about.
– David Hammen
Nov 7 at 22:02
add a comment |
up vote
5
down vote
up vote
5
down vote
How do you confirm ignition in the combustion chamber of a rocket?
Sometimes, you don't. Pressure sensors, flow sensors, and such are yet another device that can fail. Moreover, what if nothing can be done / needs to be done if ignition fails to occur? In the case of the Shuttle (Organic Marble's answer), all three main engines were needed for launch. Something could be done and had to be done in the case of failed ignition: All engines needed to be shut down and the ignition of the solid rocket boosters needed to be prevented. The Shuttle used a number of sensors, pressure sensors and flow sensors, to determine whether launch needed to be aborted in the 6.6 seconds between the command to light the main engines and liftoff. This Redundant Set Launch Sequencer (RSLS) abort happened five times, at least once because of a failed sensor rather than a true problem.
Consider instead an uncrewed vehicle that has been launched and released from the launch vehicle. Suppose the vehicle has a zero fault tolerant main engine and a non-redundant set of zero fault tolerant attitude thrusters. The engine and attitude thrusters either work or they don't. Nothing can be done, and nothing needs to be done with if an engine fails. Vehicles such as these typically do not have sensors that detect ignition.
Another way to avoid those very expensive and failure-prone sensors is to make the navigation sensors such as accelerometers and rate gyros serve dual purpose as thruster failure detection devices. The point of using thrusters is to change the vehicle's translational or angular velocity; thruster failure should, in theory, be detectable via the navigation sensors. NASA used this approach for Mini AERCam, Synchronized Position Hold Engage and Reorient Experimental Satellite (SPHERES), and for X-38. Mini AERCam and SPHERES used cold gas thrusters; all that's needed are flow sensors. These vehicles are so small that a little puff of cold gas makes the vehicle respond very quickly. This responsiveness made Mini AERCam and SPHERES thruster failures rather easy to detect via the navigation sensors.
X38 on the other hand was a bit balky and responded rather slowly to thruster firings. This made X-38 thruster failures rather difficult to detect via the navigation sensors. Using navigation sensors to detect thruster failures suffered a noise to signal problem. Statistical techniques were needed to gradually let the navigational signal from a thruster failure gradually rise above the noise inherent in the navigation sensors.
How do you confirm ignition in the combustion chamber of a rocket?
Sometimes, you don't. Pressure sensors, flow sensors, and such are yet another device that can fail. Moreover, what if nothing can be done / needs to be done if ignition fails to occur? In the case of the Shuttle (Organic Marble's answer), all three main engines were needed for launch. Something could be done and had to be done in the case of failed ignition: All engines needed to be shut down and the ignition of the solid rocket boosters needed to be prevented. The Shuttle used a number of sensors, pressure sensors and flow sensors, to determine whether launch needed to be aborted in the 6.6 seconds between the command to light the main engines and liftoff. This Redundant Set Launch Sequencer (RSLS) abort happened five times, at least once because of a failed sensor rather than a true problem.
Consider instead an uncrewed vehicle that has been launched and released from the launch vehicle. Suppose the vehicle has a zero fault tolerant main engine and a non-redundant set of zero fault tolerant attitude thrusters. The engine and attitude thrusters either work or they don't. Nothing can be done, and nothing needs to be done with if an engine fails. Vehicles such as these typically do not have sensors that detect ignition.
Another way to avoid those very expensive and failure-prone sensors is to make the navigation sensors such as accelerometers and rate gyros serve dual purpose as thruster failure detection devices. The point of using thrusters is to change the vehicle's translational or angular velocity; thruster failure should, in theory, be detectable via the navigation sensors. NASA used this approach for Mini AERCam, Synchronized Position Hold Engage and Reorient Experimental Satellite (SPHERES), and for X-38. Mini AERCam and SPHERES used cold gas thrusters; all that's needed are flow sensors. These vehicles are so small that a little puff of cold gas makes the vehicle respond very quickly. This responsiveness made Mini AERCam and SPHERES thruster failures rather easy to detect via the navigation sensors.
X38 on the other hand was a bit balky and responded rather slowly to thruster firings. This made X-38 thruster failures rather difficult to detect via the navigation sensors. Using navigation sensors to detect thruster failures suffered a noise to signal problem. Statistical techniques were needed to gradually let the navigational signal from a thruster failure gradually rise above the noise inherent in the navigation sensors.
edited Nov 7 at 18:52
answered Nov 7 at 18:17
David Hammen
29.2k167126
29.2k167126
But sensors used for telemetry data may be used for ignition detection too.
– Uwe
Nov 7 at 19:58
@Uwe - It doesn't matter whether the failure detection is an onboard or ground control function. The data will come from various onboard sensors, and that's what the question is asking about.
– David Hammen
Nov 7 at 22:02
add a comment |
But sensors used for telemetry data may be used for ignition detection too.
– Uwe
Nov 7 at 19:58
@Uwe - It doesn't matter whether the failure detection is an onboard or ground control function. The data will come from various onboard sensors, and that's what the question is asking about.
– David Hammen
Nov 7 at 22:02
But sensors used for telemetry data may be used for ignition detection too.
– Uwe
Nov 7 at 19:58
But sensors used for telemetry data may be used for ignition detection too.
– Uwe
Nov 7 at 19:58
@Uwe - It doesn't matter whether the failure detection is an onboard or ground control function. The data will come from various onboard sensors, and that's what the question is asking about.
– David Hammen
Nov 7 at 22:02
@Uwe - It doesn't matter whether the failure detection is an onboard or ground control function. The data will come from various onboard sensors, and that's what the question is asking about.
– David Hammen
Nov 7 at 22:02
add a comment |
EdwardJ is a new contributor. Be nice, and check out our Code of Conduct.
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