When I watched the launch of HYLAS-4 and Superbird-B3 on Ariane 5 ECA, for a moment it seemed that ESA is also experimenting with fairing recovery - with a fairing which flaps its wings and flies like a beautiful white swan to its destination. It can be seen in this video at 3:25 after the launch (link should start the video just before the event).

ULA's fairing seems to be doing the same.

The only other fairing I am familiar with is the one used by SpaceX. The fairing is mainly composed of aluminum honeycomb structure covered by what I suspect is carbon fiber or fiberglass. I would expect this structure to be rather stiffer than what was on the Arianespace video.

Are all payload fairings similar in their mechanical properties?

Is it the fairing separation mechanism that causes the Arianespace fairing to flex so much?

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    $\begingroup$ In your video, the announcer says that 9 km/sec is necessary for orbit, and says that that is 9,000 km/hour. The flapping fairing isn't the only strange thing about this video! $\endgroup$ – uhoh Apr 15 '18 at 20:19
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    $\begingroup$ @uhoh: Yeah, I noticed as well. Americans aren't the only ones getting caught in difficult unit conversions. Maybe it's time to finally introduce metric time :-) $\endgroup$ – JohnEye Apr 15 '18 at 20:41
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    $\begingroup$ @uhoh maybe he was confused with Decimal time, but even then, the conversion would have been wrong :) $\endgroup$ – Antzi Apr 16 '18 at 2:21

That ULA video was great.

I googled for "fairing vibrational modes after jettison" and came up with a lot of interesting links. The prize is probably this paper "Simulation of the behavior of a payload fairing during separation" which includes this graphic showing motion just like what's in the video.

enter image description here

and this description

The vertical jettison corresponds to a pyrotechnic event taking place in the plane xz which separates the fairing into two halves.

This paper seems to be based on an Ariane fairing (although it never came out and said it directly). After reading this, I think I'd conclude that similar fairings split in a similar fashion are going to "flap" like that..however, materials and construction types are going to vary the magnitudes and periods of the oscillation.

Another paper "Structural Dynamics Analysis for Payload Fairing with Ejectors during Jettison" does a similar analysis for Long March fairings. The results are generally similar except for this fairing the flapping motion seems to be the fourth vibrational mode (the other paper found it to be the first mode).

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  • $\begingroup$ Wondering if the OP was looking for something about the stiffness of a half-fairing vs stiffness of the completely attached fairing (structures generally, shells specifically) $\endgroup$ – Anthony X Apr 16 '18 at 3:24
  • $\begingroup$ @AnthonyX: Not really, I'm pretty sure that the fairing is rather stiff when attached. Though it would be interesting to see just how soft they could make it without crumpling at Max Q. Also, one could possibly make up for a thinner fairing by pressurizing it, but the weight of the gas could probably overcome the savings. $\endgroup$ – JohnEye Apr 16 '18 at 8:08

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