Will a rocket accelerate faster if the air in front of it is sucked away? Imagine a rocket with a super powerful vacuum pomp on top of it. These pomps or whatever should manipulate the airflow in front (or around) the rocket. What causes the rocket to accelerate quicker and probably will also spare fuel.
Do you think it is possible?
If it is possible than it would be very helpful for in the Hyperloop projects.
 A: For fast moving objects like rockets the aerodynamic drag is dominated by inertial forces. Although air may seem weightless it actually weighs about $1.2$ kg per cubic metre (at ground level - the density decreases with altitude). A the rocket flies it has to push the air out of the way. That means it has to accelerate the air, and accelerating the air takes energy and causes the drag.
Suppose the rocket has to accelerate a mass $M_\text{air}$ of air per second to an average velocity of $v_\text{air}$, then the change of momentum of the air per second is just $M_\text{air}v_\text{air}$. Force is defined as the rate of change of momentum, so we get a force $F$ that is given by:
$$ F = M_\text{air}v_\text{air} $$
and this force is the drag. With some handwaving arguments we end up with the equation for quadratic drag:
$$F = \tfrac{1}{2}C\rho A v^2 \tag{1} $$
where $\rho$ is the density of the air, $A$ is the frontal area of the rocket and $v$ is the speed of the rocket. The parameter $C$ is a fudge factor that encapsulates all the complicated dynamics of the air flow that we don't really understand.
Anyhow, the point of all this is that suppose we try using a pump to pump the air out of the way in front of the rocket. The pump has to move the air out of the way just as a rocket without a pump does, and to do this the pump requires energy just as a rocket without a pump does. So we haven't saved any energy by using a pump and the drag will be just as great.
If a pump could somehow optimise the air flow then that might reduce the constant $C$ in our equation (1) for the drag above. However rockets are already designed to optimise the air flow - that's why they're pointed at the top! given the extra cost and complexity of a pump, at best it wouldn't make enough difference to be worth it and at worst it would reduce the streamlining at increase the drag instead of reducing it.
