McDonald’s metal STRAW is smartly engineered for double layer drinks

Double layered drinks are a bit tricky to drink. You have to finish the bottom layer first before consuming the upper one. Or you could just let it melt, mix it and destroy the individual tastes. None of those two options seem efficient. Well, the new McDonald’s metal straw will give you an extra option.

McDonald's Straw - Redesigned and re-engineered by aerospace and robotics engineers tb

Would you like to drink equal parts of both the layers at the same time? Turns out that using some basic physics of fluid dynamics, you can actually do that.

McDonald's Straw - Chocolate Shamrock Shake
The overly engineered McDonald’s straw is designed to help customers enjoy the Chocolate Shamrock Shake and its variants. You can keep the straw and use it for other drinks later ¯\_(ツ)_/¯

How was it made?

The straw is J-shaped, has three extra holes and is made using thick plastic. The curved part of the straw goes into the glass, and the strategically positioned holes allow the user to drink 50% of each layer. Oh, and it is the brainchild of engineers who have worked on things like Project ARA and other projects for DARPA and NASA.

It’s the product of comedic over-engineering, involving whiteboards, physical prototypes, CAD models, and even fluid dynamics simulations.
The new McDonald's straw
The new McDonald’s STRAW (Suction Tube for Reverse Axial Withdrawal)

According to one of the engineers who worked on the project, the seemingly easy task seemed to unravel in complexity and presented quite a few engineering and scientific challenges. Many of their early prototypes hit snags when they couldn’t suck in the exact proportions or got a puff of air instead of the shake.

So they did what you would expect any engineer to do. Got a lot of milkshakes, stored them in a refrigerator for testing, got into the thick of things and decided to nerd it out.

They modeled the axial flow of the milkshake in a software, defined the diameters of the holes and the straw, put the Fibonacci sequence to use and did a lot of testing. The result was, according to them, “a marvel of fluid dynamics.”

McDonald's straw - engineering team
Fluid dynamics in action

McDonald’s has produced about 2000 of these straws. These were given out with the chocolate shamrock shake in 80 cities in May 2017. If it is well received, the multi-billion dollar chain will mass produce them for a wider market in the future.

Check out their amusing commercial!

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