I got this idea from looking at a tent pole. They have all these pieces that snap together and fit inside a cloth groove. What if I filled a cape with a bunch of those say 20 mm long with a 2 mm diameter? Instead of putting the pieces together with my hands, I'd have them joined together at the press of a button. The button would turn on the electromagnets and they would go rigid.

Would this work?

Work means be able to carry an average man if he jumped off a cliff a greater distance horizontally than the height he jumped from and leave him relatively unharmed.

This is my first question, so sorry if it's a bit vague. I am open to suggestions for specificity/clarity.


Aarthew III


closed as off-topic by JDługosz, Hohmannfan, bilbo_pingouin, Gianluca, mjr Mar 9 '16 at 13:53

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  • $\begingroup$ I'm pretty sure you can't fly with a cape no matter how it's put together. Maybe focus the question by talking about using tent-pole technology on the collapsible wing on an ultra-light? Something we already know can glide. $\endgroup$ – Schwern Mar 9 '16 at 2:12
  • $\begingroup$ For your question as such, it is not clear what you are trying to achieve. So it would be hard to answer whether it would "work". However, I fail to see how that is about worldbuilding at all..? $\endgroup$ – bilbo_pingouin Mar 9 '16 at 13:08
  • $\begingroup$ @Schwern Wingsuits are a thing. $\endgroup$ – Polyducks Mar 9 '16 at 13:47
  • $\begingroup$ @Polyducks Wingsuits don't fly in the sense that they cannot generate enough lift for you to climb no matter how fast you go. You're always falling in a wingsuit, but they transfer some of that energy to velocity. And they require a parachute to land. $\endgroup$ – Schwern Mar 9 '16 at 17:50
  • 1
    $\begingroup$ @Schwern Ahh, the old Buzz lightyear 'falling in style'. $\endgroup$ – Polyducks Mar 10 '16 at 11:51

Assuming you had a wing design that already worked (Batman's cape will not) and the poles are already sufficiently strong and rigid, this could work.

Collapsible tent poles work by slotting the pole into a metal sleeve. There's also a bungie cord inside the pole to (lightly) pull the pieces together. The sleeve is typically stronger than the pole, as campers know tent poles tend to break at the pole, so in terms of strength there's no problem replacing complete poles with collapsible ones. It will add some weight and reduce flexibility, but it should be manageable.

Rather than joining the poles using magnets, it would be wise to retain the sleeve and cord system. It's proven tech, and your wing won't fall apart if you lose power. Where magnets come in is to pull the pole into the sleeve and ensure it's firmly seated. With some clever shaping of the ends of the poles and sleeves (funnel tip for the sleeve, round tip for the pole), this might be done reliably... though getting the complex shapes and joints necessary for a collapsible airfoil will be tricky. However if you lose power you lose tension and a pole may slip out of its sleeve. Perhaps you could have a locking mechanism, but it would also have to unlock.

What would be even more reliable is to cause the bungie cord to contract pulling the ends of the poles into the sleeves. This could be a simple mechanical operation pulling on the cord at the middle of the pole, or by separating two pole pieces and inserting a spacer.

Poles at start  =====*--=====*--=====*--=====*--=====*--=====

Open a gap      =====*=====*=====*------------=====*=====*=====

Insert spacer   =====*=====*=====*-=========*-=====*=====*=====

Release tension =====*=====*=====*=========*=====*=====*=====

To collapse, remove the spacer releasing the tension on the cord.


Having the cape go into that shape is certainly possible, although you would need a substantial amount of electric power if you wanted it to be strong. Assuming you wanted to use the cape to fly (or even glide) though then you have a bigger problem.

Or a smaller problem.

The cape isn't big enough. Look at wing suits for example. The terminal velocity wearing a wing suit is still 110mph, you can fly around nicely but you certainly can't land.

A hang glider or parachute needed to land at a more manageable and survivable speed is much larger than Batman's cape.


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