Hello everyone, I am making a paper on the possible applications for nuclear fusion. One of these possible applications is a Bussard ramjet. I'm trying to calculate if Bussard ramjets are feasible, based on their thrust and the drag they experience. A Bussard ramjet would use a very big electromagnetic field to collect hydrogen from its surroundings. These hydrogen atoms are compressed by the electromagnetic field until the atoms fuse. The energy of the nuclear fusion can then be used to accelerate the spaceship. I have a about Bussard ramjets. First, I know that Bussard ramjets probably won't work due to the drag they experience from collecting hydrogen and accelerating the hydrogen atoms to the speed of the spaceship. I calculated with the equation a = π r2 ρ η c2 / M from http://www.dangermouse.net/gurps/science/ramjet.html that a spaceship with a mass of 9.8 * 106 kg and a electromagnetic field radius of 3000 km would have an acceleration of 1g. For η I used the factor 0.00753 (0.753%) of hydrogen fusion and for ρ I used the value 5 * 10-21 kg/m3 based on 0.3 hydrogen atoms per cm3 in outer space. Using F = m*a, I calculated that this spaceship would have a thrust of 9.6 * 107 N. Furthermore, I calculated (with an equation from that website) that the minimum speed for nuclear fusion to be possible has to be 0.06c. Now, I want to calculate the drag force of the hydrogen atoms on the spaceship when it has a speed of 0.06c. My question is, how do you calculate the drag force of hydrogen atoms on a Bussard ramjet when you know all these other values? P.S.: I calculated the mass for the spaceship (9.8 * 106 kg) with the equations from dangermouse and a picture from http://orbitalvector.com/Interstellar Flight/Bussard Ramjet/Bussard Ramjet.htm which states that a ramjet with a scoop radius of 3000 km and an acceleration of 1g would have to go at least 0.06c in order for the fusion reaction to function.