Negative G - questions
Thread Starter
Join Date: May 2000
Location: UK mainly
Posts: 322
Likes: 0
Received 0 Likes
on
0 Posts
Negative G - questions
I would like to know when you pull negative G in Aircraft do you reduce the stall speed and induced drag or what?
If you pull zero "G" what happens to the stall speed and what happens to the drag ?
I only ask because I was in these situations (under instruction)
last week , I prefer positive "G" I have decided!
Any answers welcomed.
thanks.
If you pull zero "G" what happens to the stall speed and what happens to the drag ?
I only ask because I was in these situations (under instruction)
last week , I prefer positive "G" I have decided!
Any answers welcomed.
thanks.
Aviator
Join Date: May 2001
Location: Norveg
Posts: 483
Likes: 0
Received 0 Likes
on
0 Posts
You'll reach the negative-g stall speed when the wings exceed their maximum negative AoA; usually at a greater airspeed than positive Vs if the airfoil is not symmetrical. At zero g, the stall speed is zero (space shuttle in orbit). Induced drag nears zero @ zero g. This is why fighters enter a gentle dive / slice manoeuvre to escape the bogeys (best acceleration). I think 
Cheers.
Cheers.
Join Date: Dec 2000
Location: Hot Section / Gas Turbines
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
not sure about the negative g but would suggest that stall speed and induced drag would be higher..as for zero g it is impossible to stall a wing that is not producing lift and induced drag would be zero as it is a by product of lift!! if you understand bernoulis theorum it will make sense
ps i dont understand the formula but think i understand the theory...
Well anyone care to shot me down in flames????
Just another cropduster
ps i dont understand the formula but think i understand the theory...
Well anyone care to shot me down in flames????
Just another cropduster
Don't worry, Dynamite Dean ... you're not alone in your preference. Humans can tolerate a much greater positive G load than we can a negative G load. (Have you ever seen someone who has experienced a "red-out" as opposed to a black-out .... an ugly sight indeed! 
)
As Crossunder and Burnercan have stated, a stall is a function of AoA, and AoA is influenced (at least in part) by load factor. At Zero-G, there is no load, so the wing will not stall. However, as you transit away from Zero-G into negative G forces, you are now increasing the load on the wing, and are therefore increasing your AoA in the negative direction. When you reach critical negative AoA (regardless of your speed) you will incur a negative-G stall.
As one example to illustrate: That's why when you're doing normal stall recoveries, it's important to unload, but you must be sure not to overdo it (i.e. push forward too much) because you might induce a stall in the negative regime.
)As Crossunder and Burnercan have stated, a stall is a function of AoA, and AoA is influenced (at least in part) by load factor. At Zero-G, there is no load, so the wing will not stall. However, as you transit away from Zero-G into negative G forces, you are now increasing the load on the wing, and are therefore increasing your AoA in the negative direction. When you reach critical negative AoA (regardless of your speed) you will incur a negative-G stall.
As one example to illustrate: That's why when you're doing normal stall recoveries, it's important to unload, but you must be sure not to overdo it (i.e. push forward too much) because you might induce a stall in the negative regime.
Last edited by McD; 25th Nov 2002 at 14:35.
