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[v1_rotate]

@shanx

Yes true and correct, sorry about that.

The Stall speed (IAS) does increase times the square root of the load factor.

[Sierra2467]

@cvchetan v1_rotate
Ok, so incase they ask- a wing stalls at the root first,unless "swept wing" is specified in which case the wing stalls at the tip first, right?
thnx again

[shanx]

@v1 rotate

Yes. Was just going to add ...

Stall speed depends on load factor.

So as an example, an aircraft that normally stalls at 70 KIAS, can be made to stall at 90 or 100 Kts (Indicated) by forcefully yanking back the controls.

(in other words, inducing more Gs hence .. increasing load factor)

[v1_rotate]

@Sierra2467

Yes, although I dont think they would ask the question that bluntly, because its still rather ambiguous. The planform is also a factor, The stall characteristics of an elliptical wing for example are not as favorable as a rectangular wing.

And also this unfavorable tendency on swept back wings can be minimized with Washout, stall strips , wing fences etc...

[SuperflyTNT]

Doubt.

When in ground effect - Lift increases and Induced drag decreases. So, when out of ground effect, Lift decreases and Induced drag inc. ? Is that right?

[Sierra2467]

are you guys doing the questions from oxford series? those who appeared last time said that oxfords level is too high for jet exam?!
any suggestions plz?

[t.a]

@flyinghigh89
I am not sure if my thinking towards this answer is appropriate or not.
But would like to recall that, on an ILS if there is a change in wind direction which if resulted in change in Ground speed, then to remain on the glide slope, then if Gs decreases then ROD decreases and if Increases then ROD Increases.(which is derived from the formula angle*100*Gs/60)

so applying this principle to your Question, when an aircraft is descending in a still air and later observed a wind change, then if we apply the vice-versa of the above (since u are not giving a correction in this scenario) and the above law is to stay on the Glide slope.

So the resultant would be that, on a Head wind (Gs Decreases ) so the rate of descent increases.

Please correct me, if u find a mistake.

Thanks.

[djajay.jayaraj]

In the last Jet Exam, Was there Any Questions Bases on Mass & Acceleration, If so anyone remember what it was ?

I remember seeing it somewhere on the Jet Air-Thread, But unable to Find it now..

AJ

[alpha_victor_romeo]

Info

I still didn't get the answer ??

Does Stall Speed change with height..??

BTW This is a question was asked to me by my friend who appeared Indigo exam last time and recollected this question..

So if you guys could help...

Also Shape of Earth : Ellipsoid or oblate spheroid..??

Wat is TVMDC type ques..??

What is geomertic Pitch..??

any idea bout Magnus Effect..??

Wat are ACW Generators..??

These are ques frm INDIGO exam first session.. Kindly post any info you might have on any of the above topics.....

[tmbpilot]

@alpha_victor_romeo-----stall speed increases with alt....description is quite theoretical ,from what i remember is it falls a little as we climb and then starts to increase and becomes more than the original stall speed....correct me if im wrong


shape of the earth strictly speaking its an oblate spheriod

geometric pitch of a prop is the horizontal distance a free propellor will cover in one rotation....effective is the actual distance and the diff between them is slip...


what an unnecessary question but magnus effect takes place when when an object is rotating it causes an whirlpool around it ...quite like shaktimaan used to do

ACW or AC wild type generators have an changing frequency ...as this generator speeds up or slows down freq changes..

@DJ Flyboy
in an turboprop ac turbine is used to drive the prop ,,in an turbojet its used to drive an compressor

correct me if im wrong anywhr

[planeboy_777]

@alpha_victor_romeo-----stall speed increases with alt....description is quite theoretical ,from what i remember is it falls a little as we climb and then starts to increase and becomes more than the original stall speed....correct me if im wrong

thats incorrect my friend........ Stall is dependent on the Dynamic pressure....which is IAS (.5x[row]x [TAS]x[TAS]) ..

the green arc in your ASI never changes if you ever noticep

[alpha_victor_romeo]

Thnx

@ above Thank you for your response.... if you dnt mind me asking

could you please refer me the books you study from... you seem to have a good understanding of the subject...

[alpha_victor_romeo]

guys i still need some formula if u claim .... it will change with altitude pls tell me the value how much if 45 kts at 8000ft 20 000 ft how much..??

[planeboy_777]

The Formula is Lift = .5 x [Density] x TAS x TAS x S x Cl(co-efficient of lift)



Stall will occsur just after when Cl reaches its Max so itzz constant for a wing...the only variable is Density and TAS

at high altitudes Density Decreases and TAS is increased automatically increased so the dynamic pressure aka IAS aka .5 x [Density] x [TAS] x [TAS] remains contant

[tmbpilot]

@planeboy_777 at lower range of altitude stall speed does not vary with alt,this is because at these low altitudes the mach number is less than 0.4 m too low for compressibility to be present.at 30000ft the mach number has increased to such an extent the rise in stall speed becomes apparent.......so rephrasing my reply"as alt inc,stall speed is initially constant then increases due to compressibility".......if u have an oxford book refer pg 7-35......

[cyrilroy21]

@tmbpilot

Are referring to IAS or TAS when it comes to stall speed ?

[Pulkdahulk]

Stall speed IAS remains the same at all altitudes.

Please refer

http://www.pprune.org/tech-log/10859...ude-stall.html

[SuperflyTNT]

Can anyone share the METAR and TAF minimums over here? Thanks.

[shanx]

@Pulkdahulk

Stall speed IAS remains the same at all altitudes.

Incorrect.

You can stall the airplane at a much higher IAS by inducing more G's.

Which is why an airplane would stall at a higher IAS, when in a really steep turn, or if the yoke is yanked back real hard.

[neels0908]

stall speed

guys....
with regard to the question on stall speed,

the formula for lift is : LIFT= (C.L) * {(0.5) * (rho) * (TAS) * (TAS)}
where {(0.5) * (rho) * (TAS) * (TAS)} is the dynamic pressure, which gives the indicated airspeed.

So, from the above equation, when we equate for {(0.5) * (rho) * (TAS) * (TAS)} , it will be : (dynamic pressure) = LIFT/(C.L)

and stall occurs when the coefficient of lift is maximum.
Hence, during stall, (dynamic pressure) =LIFT / (C.L max)

and since C.L max is constant for an aerofoil and the load factor is directly proportional to the Lift produced during straight and level flight, if the load factor acting on an A/c is the same, it will always stall at the same IAS.

Also, when (C.L) = (C.L max) , that is the AoA at which the A/c will always stall irrespective of the Altitude or the speed. { Please note that whenever most of the books say speed, they mean the TAS (v) }

Now , from the very first equation , if we equate for the speed {i.e TAS (v)}, we get

(TAS) * (TAS) {or (v squared)} = [ LIFT / { (C.L max) * (0.5) * (rho) }]


hence TAS {or (v)} will be equal to the square root of the expression on the right hand side of the above equation.

From the derived equations for the TAS {or (v)} and the IAS , we see that density (rho) is involved only in the equation,

So.... Under constant load factor, the IAS at which an A/c will stall will always remain constant, but the TAS will vary inversely with density

i.e , the A/c will stall at a higher TAS at higher altitudes, since density is lower.


Hope this helps .
Best o Luck to all u guys....