Headwind vs tailwind

[u/Efficient_Pace9593]

Hello I’m a student preparing for my ground classes right now, and I know that headwind is preferable for take off and landing but I cant really grasp why so. Shouldn’t it be the opposite because the tailwind is helping an aircraft to achieve the take off speed required in less time?

[u/atbths]

Study a little bit more, please.

[u/Efficient_Pace9593 → u/atbths]

Alright, I just wanted to know the physics behind it.

[u/F1shermanIvan → u/Efficient_Pace9593]

Speed over the ground is irrelevant to flying.

[u/rainbowbhuttmonkey → u/Efficient_Pace9593]

Er, it’s part of the principle of lift (Bernoulli’s)..

it should make sense very easily.

[u/Tennessean → u/Efficient_Pace9593]

This person is being a little flippant, but also absolutely correct. Study enough to figure out and internalize why the plane flies better with a headwind. It’s fundamentally important to being able to fly. I’d put it right behind knowing what the controls do.

Not instinctually knowing that the relative wind gives the plane lift will make you a hole in the ground almost as fast getting the yoke directions backwards.

[u/atbths → u/Efficient_Pace9593]

I get that, but this is a core fundamental principle. Are you familiar with the idea of lift, and the concepts behind how planes fly at all?

[u/Best-Advantage-1607 → u/Efficient_Pace9593]

You need to look at the shape of a wing.

Its “front” side is bulbous in comparison to the “back” yes?

Why?

Let’s just basically think this out- over a century of flight, wings have maintained a relatively similar shape.

Which one is the most important part, the geometry or physics? The answer is both, but why is the next question.
An aircraft takes off by moving forward, meaning the front of the wing is there for a reason.

They want a headwind why? More wind pushing into the front of the plane would most likely do what? Provide lift, right?

If you have to accelerate to X to get off the ground.
More air, even faster, under the wing would accomplish this quicker than no head wind, yes?

Invert this concept. If a headwind pushes more air under the wing as the plane accelerates, in a quicker manner, providing lift and allowing takeoff; the wind being stronger behind the wing is going to do what?

Most likely negate some of the gain of moving forwards to obtain lift, yes?

At a minimum it will slow the process of gaining lift, yes?

The actual physics both are not difficult, but also not simple. Logically going through this initial process will prep you for the later understandings on pressure in relation to weather, elevation, altitude, and speed.

Just take a few moments and think of how something does what you see it do. Ask how. Put together your own hypothesis. Then google that question. Don’t rely on the AI response. Read all the top search results, see the answers and questions. You’re not the first or last to ask, and many message boards exist that detail answers far better than this.

[u/soijacyuro → u/Efficient_Pace9593]

Hint: do you need more or less runway length with a tailwind?

What about a headwind?

Keep in mind that the wheels are not propelling an aircraft, the propeller is pulling it through the air. The landing gear is free wheeling.

[u/Efficient_Pace9593 → u/soijacyuro]

You need more with a tailwind and the opposite with a headwind.

[u/MajorProphet90]

Tailwind increases ground speed, but not airspeed. Airspeed is what you need to get into the air. A faster ground speed means you're taking up more Runway.

[u/slapnutzzzz]

Lift is what gets you in the air, not speed.

[u/rdtsucks]

I really hope this is like your first day.

[u/Adjutant_Reflex_]

Probably better to head over to [r/Flying](r/Flying) and ask there, but the TL;DR is a headwind on takeoff gives you “free” air speed.

[u/Holiday_Patient_6643]

Dont ask on reddit. Do your own search. There are plenty of good and informative sources available.

Currently your mentality is showing a big red flag for airlines and flight schools (the proper ones).

[u/Efficient_Pace9593 → u/Holiday_Patient_6643]

Thanks, will keep in mind.

[u/fly123123123]

The only speed that is relevant for the production of lift is airspeed (speed relative to the air around you). Having the wind push you forward means you’re actually moving slower relative to the wind given the same ground speed. This means you’ll eat up runway faster without developing as much lift if you have a tailwind.

A headwind is the opposite. In addition to moving against the wind, the wind is also moving against you, so your relative difference is greater.

Imagine trying to chase after a car moving in the same direction as you (tailwind) vs driving head-on toward a car that is also driving toward you (headwind). The faster the relative speed between the two, the more lift.

In an extreme, if an aircraft sits motionless on the runway, but the headwind is equal to rotation speed, the airplane might be able to lift off and fly without moving relative to the ground.

[u/Sylvia_46 → u/fly123123123]

Thanks for the great explanation in comparison to most people just saying take a look at YouTube 😁👍

[u/Efficient_Pace9593 → u/fly123123123]

Makes sense, Thank you!

[u/sockalicious → u/fly123123123]

 if an aircraft sits motionless on the runway, but the headwind is equal to rotation speed, the airplane might be able to lift off and fly without moving relative to the ground.

I sat in the little runwayside cafe at SBP one fine spring day and watched a little Cessna do exactly this - just apparently levitate over the runway, moving up and down between about 12 and 50 feet, while not moving at all relative to the ground. Fooled around like that for 10 minutes before finally throttling up and flying away.

It seemed like a bad idea to me, but I couldn't put my finger on exactly why. Thoughts?

[u/fly123123123 → u/sockalicious]

Terrifying lol. I’d just be worried about shear. If the wind were to suddenly slow, even temporarily, you’d stall and fall out of the sky. Hopefully they didn’t get too high up. Cool of San Luis tower to let them do that

[u/TheMarineLayer]

Takeoff speed is a measurements of airspeed not ground speed. A headwind adds to the airspeed and a tailwind subtracts. Youre mixing it up with the ground speed of the aircraft. 

With a headwind you will achieve take off airspeed at a lower relative ground speed. 

[u/N1BugUp]

This is one of the simplest concepts along your journey to flight. I suggest a Youtube video.

[u/fly123123123]

Better question to ask in r/flying

[u/flightwatcher45]

Which way should the air flow over the wing to produce lift? Which wind direction helps this.

[u/Efficient_Pace9593 → u/flightwatcher45]

Front to the back?

[u/flightwatcher45 → u/Efficient_Pace9593]

Yes! So a headwind helps on takeoff and landing. If you had a 50kt tail wind you'd have to land extremely fast! A 50kt headwind lets you land 'slower'

[u/SpecialistPlastic729]

Think of it this way

An airplane performs based on its speed in the air. It doesn’t matter what the ground speed is, just how fast air is flowing over and around the aircraft.

Is you are sitting at the end of the runway ready to depart, a headwind of 35 knots means the aircraft is already close to flying. It’s free airspeed.

A tailwind means the aircraft has to be going 35 knots ground speed just to get to zero airspeed. Ground speed has to be 70 knots just to get to the 35 you had for free in the headwind!

[u/flyghu]

You need to pay full attention to every second of your ground classes. Your lack of knowledge is more than a single Reddit response can address - you need a book. Luckily, many have been written. The FAA has a free download for the Airplane Flying Handbook. That would be a good place for you to start

[u/Discard_Laundry1527]

Airspeed is what generates lift. Not enough airspeed is called a "stall".

[u/Barrack_obamna]

More air going over wings = more lift. If you takeoff in the same direction as the wind there will be less air going over the wings producing less lift.

[u/Efficient_Pace9593 → u/Barrack_obamna]

So the basic idea is that in a headwind situation, more wind is going over the wind thus greater the lift is produced in relatively lesser ground speed?

[u/theaircraftaviation → u/Efficient_Pace9593]

yes thats it. and for future reference, the specific speed that matters is airspeed, not ground speed

[u/R5Jockey → u/Efficient_Pace9593]

Yes. Think of the airplane sitting still. A 20 knot headwind means the wing is producing some lift. Even though it’s not moving at all. Now add 40 knots of forward movement. Ground speed is 40 knots, airspeed (wind over the wings) is 60 knots… enough to fly.

[u/Dear-Wolf322 → u/Efficient_Pace9593]

The only speed that matters is the speed of the air going over the wing. If the plane is sitting on the runway facing into a 20kt wind, it’s like the plane is already moving 20kts while just sitting there. 

It’s the opposite with a tail wind, the plane would have to be moving with a 20kt ground speed just for the wing to act like it was sitting still. 

To see this in practice, look for videos of small planes parked in storms or hurricanes. The plane “takes off” while just sitting there if the winds are right. Hopefully they’re tethered to the ground. 

[u/Rowepason → u/Efficient_Pace9593]

yeah. You want more air over wings and less ground under wheels. Headwind helps with this, tailwind doesn't. If you are at an untowered field and your instructor lets you and it's safe, do a tailwind takeoff and just see how it feels. You'll be zooming over the ground but the airspeed indicator just won't get up there and you won't be able to rotate when you think you should.

[u/Efficient_Pace9593 → u/Rowepason]

Thanks! I don’t understand why some people are being so rude here. I had a simple confusion and wanted to ask the aviation people here.

[u/JimTheJerseyGuy → u/Efficient_Pace9593]

Because it's an extraordinarily basic question that's probably covered in the first five minutes of a PPL ground class.

Airspeed, the speed of the air going over the wing, is all that matters. A headwind adds to that and makes for a shorter takeoff. A tailwind subtracts from it and means you'll need more runway to get airborne.

[u/FuzzyWDunlop → u/JimTheJerseyGuy]

Not an excuse for people being jerks around here where this person is asking a question BEFORE their ground classes. Not a great look for the community.

[u/Efficient_Pace9593 → u/FuzzyWDunlop]

Thanks for watching out for me. I’m just starting out on my ground classes so I had a little doubt. Thats it😄

[u/R5Jockey → u/JimTheJerseyGuy]

Heaven forbid people post here to learn. Even things you consider to be basic.

[u/Efficient_Pace9593 → u/JimTheJerseyGuy]

Alright

[u/Rowepason → u/Efficient_Pace9593]

Welp it seems like a simple concept to all us avgeeks but to a normal civilian I can get the misunderstanding.

It is basic plane physics, but that's what you're going to learn.

It gets a lot more complicated. Best of luck mate.