1
vote
1answer
254 views

Nose cone design for minimal drag

What formula defines a curve for a nose cone with the minimal possible drag? The nose cone is attached to a cylinder (assume it goes on forever). The volume of the nose cone is not relevant. The ...
5
votes
2answers
169 views

How can you calculate air resistances at different speeds?

I've read that at 50mph air resistance to an average car is the equivalent of driving through water and at 80mph it's the equivalent of driving through oil. I can't find any references online to ...
2
votes
0answers
130 views

What is wrong with this downforce calculcation?

I tried calculating the downforce of a spoiler I need for a robot. I used this formula. $$F = \frac{1}{2}Ac_a\rho v^2$$ Where $\rho$ is air density, $v$ is the speed of my robot, $c_a$ is the lift ...
0
votes
2answers
211 views

Aerodynamics drag of hollow cylinder vs solid cylinder of the same cross area?

I wonder how a hollow cylinder at the same cross area perform vs a solid one, i.e the hollow cylinder has larger radius? I guess they have a similar drag, is that true?
6
votes
2answers
631 views

Could some design of a propeller be used in both air and water?

Propellers in water are smaller in diameter. They also move more slowly. On the other hand, aircraft propellers are larger in diameter, have narrower blades and operate at very high speeds. An ...
1
vote
2answers
278 views

Forces on an aircraft - thrust, lift, drag, weight

I'm extremely sceptical about the wikipedia page on aircraft flight mechanics. When describing 'straight climbing flight', it says: lift is unable to alter the aircraft's potential energy or ...
1
vote
2answers
148 views

Estimating drag due to wind - ribbon-shaped sail

In the countless calculations and discussions concerning the "space rope" I've never found any addressing its capability to resist winds. Consider, as in most current works, it's a 1m wide ribbon, ...
2
votes
1answer
322 views

Limitations of drag equation

The magnitude of the air resistance for objects with Reynolds numbers greater than 1000 is given by the formula: Why it does not hold for objects with lower Reynolds numbers? Can I use this ...
0
votes
3answers
356 views

Bicycle Wheel Drag in Slipstream

I was recently driving behind a car that had a bicycle mounted on a carrier over the rear bumper. The bicycle wheels were not bound so they were rotating in the slip-stream of the car. I wonder, the ...
2
votes
2answers
350 views

What would be an appropiate shape for a parachute?

I'm trying to design a parachute that minimizes the descent velocity, but I'm not sure what shape I should use. From what I've read, ellipse-shaped parachutes are too aerodynamic and minimize drag, ...
3
votes
3answers
876 views

Does wind speed things up or accelerate things?

This question may seem odd, but I can't think of anything better. So I'll go straight to the point. Let's say there's a projectile in air going east, shot at a certain angle, with a certain speed. ...