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I'm working on a tabletop roleplaying game about witches. I have most of the mechanics of broomsticks worked out, but I'm having trouble deciding on top speeds. Speed limits are not a result of how fast the broomstick itself can be made to go, but are imposed by air resistance ripping the witch off the stick at high speeds.

I'm looking for two speeds; one for witches sitting sidesaddle, and one for witches astride the broom. Novice witches sit sidesaddle, because it's easier to balance that way, whereas more experienced witches sit astride it. Sitting astride the broom allows them to bend forwards and better streamline themselves, as well as giving them a better grip.

Other facts that might be pertinent: The lift occurs entirely in the broomstick, and the witch must rest upon that. The broom are ridden bristles-backwards. For the purposes of this discussion, the witch is performing no magic besides the magic that lifts and moves the broom.

Assume that the witch has just enough practice to balance on the broom, but she is by no means an athlete. Her grip strength, weight, and so on are average for humans. How fast can she go without being ripped off by the oncoming air?

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    $\begingroup$ maybe it'd be fine to compare it to a bike or motorcycle? i dunno it might just be worth a shot, and you'd have to minus the speed a bit due to the fact that the witch doesn't have a handle specifically, they just have the stick to hold onto, and also nothing for their feet. $\endgroup$ – michael griffin Jan 22 at 3:02
  • $\begingroup$ I thought veteran use broomstick while padawan use dustpan? $\endgroup$ – user6760 Jan 22 at 5:49
  • $\begingroup$ Your witch can create a cone-shaped force-field in front of her so that she doesn't face the air resistance at all. The force-field doesn't need to be strong only needs to slice air, insects or birds can go through. Maybe the novice witches can't do it, but the experienced can, the more experienced the witch is, the stronger the force-field. $\endgroup$ – V.Aggarwal Jan 22 at 8:31
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    $\begingroup$ @V.Aggarwal - a cone shaped force-field? Wasn't aerodynamics the underlying reason for a witch's cone shaped hat? ;) $\endgroup$ – G0BLiN Jan 22 at 8:37
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    $\begingroup$ @michaelgriffin also motorcycles (especially ones designed to go fast) have seats that keep you from sliding backwards and fairings that hold off the wind. Combined with what you have mentioned I feel like the max speed for brooms is considerably lower than motorcycles. $\endgroup$ – RancidCrab Jan 22 at 14:23
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Not the answer you're looking for: I believe the answer is that it's effectively impossible.

For drag itself your limit is going to be drag vs grip strength. I believe your witch will be subject to their own weight at something around 140 mph, drag goes at the square of velocity. However, you're gripping the broom in a very inefficient way. Note that you can test this yourself (but see my second point!!)--clamp a strong broomstick between two supports, wrap a rope around your chest, then over something behind you so it dangles down. How much weight on the rope can you resist?

However, there's a far bigger problem here--how are you going to sit on that broomstick in the first place? Your center of mass is above the broomstick, the broomstick is round. You're going to have a major problem avoiding rotating around the broomstick. (Note that this could be overcome by strapping enough weight to your feet, but the weight needed is considerable.)

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    $\begingroup$ @pyrrhicPachyderm It's 120 mph spread-eagled, 180 mph with your body aligned with the wind, my 140 is an extrapolation from those. (I'm looking at numbers for skydiving.) In my experience stair railings have supports underneath, your broomstick is smaller, rounder and has nothing underneath. $\endgroup$ – Loren Pechtel Jan 22 at 5:19
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    $\begingroup$ If you're doing 140 mph, you really, really want good goggles, or better yet a full-face helmet, and good leathers. (Honestly, while I've done that sort of speed on a motorcycle, it's always been with a full fairing. 60-70 is as fast as I'd want to go without one.) And you certainly don't want to run into a rain or hail storm, or get hit in the face by a wasp (extremely not fun). $\endgroup$ – jamesqf Jan 22 at 5:20
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    $\begingroup$ @LorenPechtel Ahh, skydiving! Thanks! Just looked at the Wikipedia page, and that even gives some figures I could use in non-terminal-velocity calculations. As for the stair railings, I did pick circular wooden ones, and avoided touching the supports, but yes, they were larger. $\endgroup$ – pyrrhicPachyderm Jan 22 at 5:33
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    $\begingroup$ @pyrrhicPachyderm i assume you haven't been buffeted by 140mph winds or done any maneuvers while sitting on your stair railing? $\endgroup$ – ths Jan 22 at 10:15
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    $\begingroup$ My takeaway is that a <ahem> hard-science flying witch would hang upside-down from their broomstick, sloth-style. $\endgroup$ – Gene Jan 22 at 16:31

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