Where do you see it as a constraint? As free molecular heating?For Pegasus, it is not just the fairing. The wings char.Also, there is interference heating.
And your question is... what?The chief difference between chemical engines and plasma engines us that chemical engines do not interact with the exhaust gases. All its thrust comes from the expansion of gases. Plasma engines use electric and magnetic fields to accelerate the plasma exhaust gases.
The energy source is different. Plasma rockets use electricity, chemical uses the chemical energy.Flame is, of course, a weak plasma.
Quote from: Jim on 08/31/2012 12:33 amWhere do you see it as a constraint? As free molecular heating?For Pegasus, it is not just the fairing. The wings char.Also, there is interference heating. Well I just had one study that claimed that heat flux is an important constraint when simulating launcher trajectories. However, I cannot find a second source, so perhaps my assumption is wrong?
Quote from: fatjohn1408 on 09/02/2012 07:08 pmQuote from: Jim on 08/31/2012 12:33 amWhere do you see it as a constraint? As free molecular heating?For Pegasus, it is not just the fairing. The wings char.Also, there is interference heating. Well I just had one study that claimed that heat flux is an important constraint when simulating launcher trajectories. However, I cannot find a second source, so perhaps my assumption is wrong?A second source would be the Atlas V User Guide:"For Atlas V 500 series missions, the PLF is jettisoned during the booster phase of flight. Before PLF jettison,the RD-180 engine is throttled down to maintain 2.5 g acceleration. Typically, the PLF is jettisoned when the3-sigma free molecular heat flux falls below 1,135 W/m2 (360 Btu/ft2-hr). For sensitive SC, PLF jettison canbe delayed to reduce the heat flux with minor performance loss. After PLF jettison, the RD-180 is throttledup."So it can be a constraint that really originates from the payload and not necessarily from the launch vehicle.
Quote from: deepseaskydiver on 12/20/2012 06:50 pmQuote from: fatjohn1408 on 09/02/2012 07:08 pmQuote from: Jim on 08/31/2012 12:33 amWhere do you see it as a constraint? As free molecular heating?For Pegasus, it is not just the fairing. The wings char.Also, there is interference heating. Well I just had one study that claimed that heat flux is an important constraint when simulating launcher trajectories. However, I cannot find a second source, so perhaps my assumption is wrong?A second source would be the Atlas V User Guide:"For Atlas V 500 series missions, the PLF is jettisoned during the booster phase of flight. Before PLF jettison,the RD-180 engine is throttled down to maintain 2.5 g acceleration. Typically, the PLF is jettisoned when the3-sigma free molecular heat flux falls below 1,135 W/m2 (360 Btu/ft2-hr). For sensitive SC, PLF jettison canbe delayed to reduce the heat flux with minor performance loss. After PLF jettison, the RD-180 is throttledup."So it can be a constraint that really originates from the payload and not necessarily from the launch vehicle.The assumption is wrong and therefore that isn't the second source.It only affects fairing jettison time. The trajectory isn't really affected.
Quote from: Jim on 12/20/2012 07:05 pmQuote from: deepseaskydiver on 12/20/2012 06:50 pmQuote from: fatjohn1408 on 09/02/2012 07:08 pmQuote from: Jim on 08/31/2012 12:33 amWhere do you see it as a constraint? As free molecular heating?For Pegasus, it is not just the fairing. The wings char.Also, there is interference heating. Well I just had one study that claimed that heat flux is an important constraint when simulating launcher trajectories. However, I cannot find a second source, so perhaps my assumption is wrong?A second source would be the Atlas V User Guide:"For Atlas V 500 series missions, the PLF is jettisoned during the booster phase of flight. Before PLF jettison,the RD-180 engine is throttled down to maintain 2.5 g acceleration. Typically, the PLF is jettisoned when the3-sigma free molecular heat flux falls below 1,135 W/m2 (360 Btu/ft2-hr). For sensitive SC, PLF jettison canbe delayed to reduce the heat flux with minor performance loss. After PLF jettison, the RD-180 is throttledup."So it can be a constraint that really originates from the payload and not necessarily from the launch vehicle.The assumption is wrong and therefore that isn't the second source.It only affects fairing jettison time. The trajectory isn't really affected. Jettison time controls when the throttle down to 2.5 G occurs, which is a pretty significant event during booster flight. I guess you can split hairs about what the conversation is about and what is meant by "constraint", but I thought it would be helpful to point out a case where significant events in a trajectory are based off of heating. After all, it seemed to me the question was looking for more sources as to why "heat flux is an important constraint when simulating launcher trajectories".
1. Is static electricity buildup ever a problem on ordinary spacecraft operations? 2. If so, are there any engineering solutions that work in the vacuum of space that are commonly applied?
1. Electric propulsion that relies on accelerating ions carries away a positive charge, thus charging the spacecraft with a negative charge that must be dissipated.
Quote from: Warren Platts on 12/26/2012 07:29 pm1. Electric propulsion that relies on accelerating ions carries away a positive charge, thus charging the spacecraft with a negative charge that must be dissipated.The exhaust beam of electric thrusters is neutralized, otherwise the positive ions would eventually halt, reverse course, and start accelerating back toward the spacecraft.
Quote from: strangequark on 12/28/2012 03:14 pmQuote from: Warren Platts on 12/26/2012 07:29 pm1. Electric propulsion that relies on accelerating ions carries away a positive charge, thus charging the spacecraft with a negative charge that must be dissipated.The exhaust beam of electric thrusters is neutralized, otherwise the positive ions would eventually halt, reverse course, and start accelerating back toward the spacecraft.The solar wind plasma serves as a ground; thus, I would guess that any positive ions would be neutralized by solar wind electrons, leaving the spacecraft with a net negative charge--hence the need for spacecraft neutralizers. However, I'm not an expert, which is the reason I asked the question in the first place.