How do planes fly into the heart of a hurricane?

20 November 2018

Hurricane_Rita_Peak.jpg

hurricane Rita

Question

Hello Naked Scientists Team. My name is Daniel, I’m from Norwich. My question to the team is why jet engines, the type you see on almost every commercial aeroplane with the large forward facing fan blades, are not used on the aeroplanes that are sent to investigate hurricanes. These still propellers albeit that these may be driven in some way by a jet engine. Is it that propeller engines are safer in high stress situations?

Answer

This week, Daniel wants to know why hurricane researchers seem to use propeller-driven planes when flying into the eye of the storm. Eva Higginbotham spoke to Dr Anna Young of the University of Cambridge's Whittle laboratory, to find out what's 'up' in the field of aeroplane engines.

Anna - Well there are two different types of aircraft engine, the smallest light aircraft have a propeller powered by piston engines much like the engine in your car. The problem with these engines is that they can't fly very high or very fast. So most planes are powered by turbine engines, and these are what we call jet engines. The jet engine then has a couple of different types. Turboprops where the turbine engine powers a propeller, and turbo fans where the turbine powers a fan. you'd normally see a turbo fan on a large passenger plane and a turbo prop on a smaller plane. So both turboprops and turbo fans get their power from a turbine. It's just in the case of a turboprop it powers a propeller in front of the engine. And in the turbo fan it powers a fan inside the engine.

Eva - So what about planes used for research into hurricanes? Do they use turboprops or turbo fans?

Anna - A lot of the planes used for hurricane measurements have turboprop engines, so they do have jet engines. They just don't have turbo fan engines. The reason turboprops are used on smaller planes is simply that they're more efficient at lower flight speeds. You don't need to fly so fast when you're just doing a short domestic flight. And that's the same when you're popping into your local hurricane. if you're flying through a hurricane. The advantage of flying slower is that you can spend longer inside the hurricane taking measurements. There is also a safety advantage in that flying more slowly is that bit safer when you're being bashed about by the wind.

Eva - But there's also a second benefit of using a turboprop engine in a really gusty environment like a hurricane...

Anna - and that is that the propulsion from the propeller is independent of the power created by the turbine engine. This is important because really big gusts or side winds can cause the propeller on a turboprop or the fan in the turbo fan to stall. So mainly, hurricane scientists use turboprops because they're better suited for the kind of flight speeds they want. But there is also a potential safety advantage.

Eva - So there you have it. No need to get in a spin. Next time will be fetching the answer to this question from Dottie.

Dottie - If you look at a Great Dane and then you look at a Chihuahua, they are so different. Do we know if a Great Dane meeting a Chihuahua recognises it as another dog?

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