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Speed and AOA: FAQ

Scotty-Bob Morgan flying an epic line — by Scotty-Bob Morgan
Scotty-Bob Morgan flying an epic line — by Scotty-Bob Morgan

With the recent academic interest surrounding Speed and Angle of Attack in Wingsuit BASE, I’m getting numerous questions on real-world connections between the two. Thank you for your inquiring minds… I’ll try my best to answer some of the more popular questions below…

1) Are smaller suits safer in Wingsuit BASE because they’re faster?

Wow, loaded question… let’s break it down a bit.

A) Are smaller suits safer?

Sometimes, yes; usually with beginner pilots needing a forgiving suit in the skydiving environment. In BASE, the answer is less absolute. Small suits are more forgiving of poor pilot control (safer)… but have longer start arcs and lower glide ratios (not safer). When in doubt, master your suit control in skydiving first. Then, take your small suits to big walls. Enjoy the journey, and please don’t rush your progression to bigger suits, lower exits and flatter glides.

B) Smaller suits are not categorically faster.

Perhaps large suits seen flying slowly give the impression that small suits are flying fast. There is no set rule with suit size and speed. If I had to guess, I would bet that the fastest suit is somewhere in the middle, neither the smallest nor the biggest.

C) Stall speed matters just as much as top speed.

For example, Suit A has a top speed of 140mph and stalls at 70mph; Suit B has a top speed of 130mph and stalls at 40mph. Suit B has a lower top speed, but has a wider speed range while still maintaining lift.

D) Everyone has a unique body profile and wingloading…

so everyone will have a unique safe speed range and stall speed on their particular suit.

Enjoy the journey, and please don’t rush your progression to bigger suits, lower exits and flatter glides

2) Is the fastest wingsuit pilot the safest?

Don’t just compare absolute speeds and think the fastest person is automatically the safest. Safe flying speed and high Available Lift is RELATIVE to YOU and your particular suit. It’s all about HOW you fly whatever suit you are flying. You can be flying a ‘safe’ suit, and yet fly poorly with little Available Lift. You can be flying a low-performance suit, and still smoke everybody on the load with your hard-earned skills. Whoever is flying with the highest energy margin above their unique stall point is the safest in terms of Available Lift. However, remember this: You can be flying faster than everyone else, but if you fly amazingly fast straight into a boulder, you probably weren’t the safest. Available Lift is one of the important ingredients, but control and judgment matter just as much.

Final of the World Base Race, 2012
Final of the World Base Race, 2012

3) I’m on a fast-flying 2-way… we’re all good and safe, right?

If two pilots are flying the same size and model suit in formation, the lighter pilot enjoys a higher safety margin and higher Available Lift. In this example, the heavier pilot must fly faster than the lightweight pilot just to maintain equal Available Lift and margin above stall. Basically, fat dudes stall at higher speeds, all else being equal.

fat dudes stall at higher speeds, all else being equal
Matt and Scotty in Brevent, France
Matt and Scotty in Brevent, France
_A wingsuit basejump exit is a controlled recovery from a stall_

4) Does the biggest suit allow for the shortest start arc?

A wingsuit basejump exit is a controlled recovery from a stall. The suit with the lowest stall speed will have the shortest start arc, after correcting for pilot technique, size and weight. There are many factors about a suit that influence how quickly it can start. Size (surface area) does matter, but there are many other important factors: airfoil shape and thickness, internal pressure, inflation time to full pressurization, etc.

Low Angle of Attack = Safety and Options in BASE

Low AOA just happens to deliver different speeds for different suits and pilot combinations, so don’t get caught up in absolute speed numbers to compare arbitrary safety between pilots and suits. If wingsuits came with calibrated AOA sensors for each model of suit, we would all be locking onto tested AOA numbers for Best Glide and Best Endurance. We don’t have that just yet, so training by GPS and ‘feel’ are pretty much all we have for now.We have an ever growing choice of wingsuits for the BASE environment, but whatever suit you choose should be flown at Low AOA and High Speed in relation to your particular stall speed. So, when I say ‘Fly Fast, Pull High’… I’m really saying ‘Fly Low AOA, Pull High’

Links to Related articles

Also by Richard Webb

Angle of Attack for Dummies 1

Angle of Attack for Dummies 2

Other topgunbase articles on ws BASE

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