# Just how much can tall skinny rockets bend? (roughly, safely)

Below is a GIF I prepared and used in an earlier question, and the answer seems quite reasonable. With a height to diameter ratio of about 70 m to 3.7 m (nearly 20:1) a weight-conscious design, focused primarily on withstanding axial stresses (e.g. thrust + drag), and allow for some flexing.

But if it bends this much in a breeze, what about in flight?

This answer references the detailed, knowledgable Flightclub simulation of a recent Falcon 9 launch. At one point when the speed of the rocket (wrt Earth's rotating frame presumably) is about 1000 m/s and the pressure must be roughly 0.06 or 0.07 bar at 22km altitude, the angle of attack is estimated to be 4.6 degrees. That would present a crushing-type force, but would it tend to bend the rocket since the fairing is so much wider than the body?

Just how much can tall skinny rockets bend? (roughly, safely)

• Are you asking specifically about how much the rockets can safely bend without breaking (if, say, a giant flying gorilla were to grab and bend them in mid-flight), or about how far they would be expected to bend under typical flight stresses (i.e. assuming no giant flying gorillas)? Commented Apr 5, 2017 at 15:46
• Hmmm - is it definitely bending, or is that movement inline with tolerances of the clamp mechanism? Commented Apr 5, 2017 at 18:00
• Related: shuttle stack twang: youtube.com/watch?v=ExfjSuJxOP8 Commented Apr 5, 2017 at 20:33
• I've heard that a spacex vp has described F9 as a "wibbly wobbly noodle" (sic) in flight (due to the high aspect ratio) and that that's one of the biggest dynamics problems that spacex faces. Commented Apr 18, 2017 at 15:17
• Related: Crushing a soda can with a hydraulic press: youtube.com/watch?v=YP_UBNwEoGs Commented Mar 19, 2021 at 8:48