Indicated airspeed with a tailwind

[waela320]

Hi ,

If i am in an approach with an indicated airspeed of 70 knots and we encounter a tailwind of 70 knots or more for any reason ,i know my ground speed will increase to 140 knots or more.

Will i stall and lose lift suddenly due wind opposing and destroying the laminar airflow over the wing with a constant indicated airspeed of 70 knots or my indicated airspeed will drop and then we stall ?
If it drops , why ? Shouldnt the IAS remain constant with a tailwind ?

Thanks in advance .

[DaveReidUK]

Have a think about inertia ...

[wiggy]

Oh no....not the downwind turns thread again......

If i am in an approach with an indicated airspeed of 70 knots and we encounter a tailwind of 70 knots or more for any reason ,i know my ground speed will increase to 140 knots or more.

Really important bit- assuming this is rapid change of wind velocity - how long is going to take for you to recover your groundspeed?

What is going to happen to your airspeed in the meantime...and what could the consequences be?

As DR has said, think inertia/momentum.

[Band a Lot]

I was driving my car the other day into a 50km head wind at a speed of 100km/h, suddenly the wind changed 180 degrees at this point and 5 seconds later what is my new cars speed per hour?

a)100km/h
b)150km/h
c)200km/h
x) my car is accelerating from 100km/h to a higher speed

[westhawk]

I was driving my car the other day into a 50km head wind

But were you on a treadmill? :eek:

[Gargleblaster]

If the wind abruptly changes from calm a 70 knot tailwind:

Ground speed will remain at 70 kts, however increasing for as long as it lasts.

Airspeed will abruptly drop to zero, and you shall drop from the sky as a grand piano with a closed lid.

[Band a Lot]

But were you on a treadmill? :eek:
A treadmill is a fixed speed external drive - please explain your comment.

The comment below you has merit.

[PDR1]

I was driving my car the other day into a 50km head wind at a speed of 100km/h, suddenly the wind changed 180 degrees at this point and 5 seconds later what is my new cars speed per hour?

a)100km/h
b)150km/h
c)200km/h
x) my car is accelerating from 100km/h to a higher speed

Actually the car would be rolling to a standstill because it was a Tesla, and by the time it had clawed its way to 100km/h it had insufficient battery charge remaining to sustain it for a further 5 seconds...

:E

[westhawk]

please explain your comment.

Certainly.


An old thread (http://www.pprune.org/private-flying/209859-aeroplane-treadmill-conundrum.html) and global phenomenon. Where physics defy understanding for many. Especially when people keep altering the original premise of the argument! (As they tend to do in such arguments) Anyway it's a fun thread.

Back to instantaneous force vectors...

[AerocatS2A]

If the wind abruptly changes from calm a 70 knot tailwind:

Ground speed will remain at 70 kts, however increasing for as long as it lasts.

Airspeed will abruptly drop to zero, and you shall drop from the sky as a grand piano with a closed lid.
This ^^

What you have is a an incredibly strong decreasing performance windshear and you will lose all of your airspeed (or lots of it, depending on how abrupt the change is). The following crash will be spectacular.

Note this has nothing to do with downwind turns as that scenario assumes a steady airmass while the OP's example has an abrupt change in the airmass.