tag:blogger.com,1999:blog-5992706309347178217.post5793793711487143471..comments2015-09-14T19:53:48.807-07:00Comments on Orbital Aspirations: THE ROCKET EQUATION AND SMALL ROCKETSedhttp://www.blogger.com/profile/17836602199553502584noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-5992706309347178217.post-37628706993440895952014-01-21T12:44:34.015-08:002014-01-21T12:44:34.015-08:00Oh, one other thing that I missed in the last repl...Oh, one other thing that I missed in the last reply.<br /><br />Knowing the Isp as a function of time or altitude, you can run simulations and determine the average Isp. It is the average Isp that you stick into the rocket equation.<br /><br />Any rocket has a varying Isp with altitude and other factors during flight (i.e. chamber pressure might change). Therefore, the rocket equation uses the average Isp which is derived by integrating the instantaneous Isp over the time and flight path. This is difficult to do analytically, so it is usually done by simulation.edhttps://www.blogger.com/profile/17836602199553502584noreply@blogger.comtag:blogger.com,1999:blog-5992706309347178217.post-87511479316956548532014-01-21T12:26:26.913-08:002014-01-21T12:26:26.913-08:00Usually, you don't need to change the equation...Usually, you don't need to change the equation. The effect of a ducted rocket motor is to give the rocket engine a higher Isp (more thrust for the same amount of fuel). So, more than likely you would have to represent the Isp either as a function of time or altitude since the Isp will change with atmospheric density, vehicle velocity and other factors.edhttps://www.blogger.com/profile/17836602199553502584noreply@blogger.comtag:blogger.com,1999:blog-5992706309347178217.post-6393789151117561112014-01-21T11:04:17.648-08:002014-01-21T11:04:17.648-08:00How would the equation be affected by an air augme...How would the equation be affected by an air augmented (ducted) rocket motor? In the case of a ducted motor not all of the exhausted mass comes from the vehicle itselfDanhttps://www.blogger.com/profile/05431889750934947429noreply@blogger.com