- #1
TimNJ
- 21
- 1
Hi everyone,
I'm working on a project for my electromagnetics class which asks us to design an electrostatic launch system that can propel an object into space. Though the bulk of the project is supposed to be about designing the accelerator plate array, I got really interested in the whole concept along the way.
We have to propel a 0.1kg golfball sized object into space. Since air resistance at low altitudes is very high, I decided to launch my object from an altitude of 35km using a high-altitude (weather) balloon.
2. The attempt at solving the problem
In Excel, I did some numerical analysis which outputs the altitude of the ball after launch with respect to time. This analysis takes both drag and gravity into consideration.
However, I found that a wide range of launch velocities will get the ball past 100km (the Karman line), but I also know that the object must be launched at a velocity at least the “escape velocity”. On the surface of the Earth, this velocity is ~11.2km/s, and at my altitude it only drops to 11.15km/s. So, at the very least my launch velocity must be 11.15km/s or else gravity will pull the object back to earth.
My dilemma is finding what the launch velocity should be accounting for wind resistance (drag). At 35km, rho, the density of air is about 100 times less than near the Earth’s surface. It’s about 0.011kg/m3, but its still not negligible if you launch at >11.15km/s.
I’ve seen this approach: ΔVlaunch = ΔVgravity + ΔVdrag. I’m pretty sure I have ΔVgravity which is 11.15km/s, but I’m not sure how to find ΔVdrag.
3.) Related Questions
How can I determine the additional launch velocity I will need to overcome drag, given the launch altitude etc.? Would it be a numerical answer? Perhaps some sort of integration is involved?
Thanks so much!
I'm working on a project for my electromagnetics class which asks us to design an electrostatic launch system that can propel an object into space. Though the bulk of the project is supposed to be about designing the accelerator plate array, I got really interested in the whole concept along the way.
Homework Statement
We have to propel a 0.1kg golfball sized object into space. Since air resistance at low altitudes is very high, I decided to launch my object from an altitude of 35km using a high-altitude (weather) balloon.
2. The attempt at solving the problem
In Excel, I did some numerical analysis which outputs the altitude of the ball after launch with respect to time. This analysis takes both drag and gravity into consideration.
However, I found that a wide range of launch velocities will get the ball past 100km (the Karman line), but I also know that the object must be launched at a velocity at least the “escape velocity”. On the surface of the Earth, this velocity is ~11.2km/s, and at my altitude it only drops to 11.15km/s. So, at the very least my launch velocity must be 11.15km/s or else gravity will pull the object back to earth.
My dilemma is finding what the launch velocity should be accounting for wind resistance (drag). At 35km, rho, the density of air is about 100 times less than near the Earth’s surface. It’s about 0.011kg/m3, but its still not negligible if you launch at >11.15km/s.
I’ve seen this approach: ΔVlaunch = ΔVgravity + ΔVdrag. I’m pretty sure I have ΔVgravity which is 11.15km/s, but I’m not sure how to find ΔVdrag.
3.) Related Questions
How can I determine the additional launch velocity I will need to overcome drag, given the launch altitude etc.? Would it be a numerical answer? Perhaps some sort of integration is involved?
Thanks so much!