Hi guys.
Ref: RUA - Recovery from Unusual Attitudes. (in a fast jet)
Sirs,
There was a video, where an F16 with instructor on board was EX: Aileron Roll in a 45 deg climb. the first was ok, the instructor. then on the second - control of the aircraft was lost - height was about 10 thou - QNH.
They recovered by about 3,000 which was just in time for agl. . . with all the warnings freaking out.
My question is - what is the likely cause of the loss of control and what can be a recovery method if the a/c is loss of control, from any but, including, this manouvre.
http://www.youtube.com/watch?v=Ca385XKYEnc...feature=related
Assuming I am aware of RUA from known conditions like Spiral dive, hi alpha low a/s - inverted (which in a fighter is no great deal) - and others - can anyone talk me through this. Understanding height above you is no good. So the hi alt here was the redeeming factor. Any tips please - even PM if you like.
Plus, any tips from experienced aerobatic pilots - pref of the fast jet variety = much appreciated. Thank You.
I appreciate I am asking a lot here but if you can at least point me in the right (attitude) direction I would be most grateful - also before the manouvre the instructor told the student to make sure that they had zero G before commencing the roll - why this - I assume to avoid what happened. . ?
Fasty.
Full Version: Fast Jets Rua
You got my "Funny" answer via PM, here is the more serious one.
Almost all departures from normal flight will result on the short or long term in the development of a spin, or an asymetry of lift over the wingspan. Sometimes the loss of control may bipass this phase and settle directly into a flat spiral, but often the initial tumbling will naturally get the machine steadily turning and establish it into the common spin. A more serious problem is when the departure follows a path which might be directly opposing gravity, here in that case there is very little forecast into saying what will happen, and physics might apply in mysterious ways here. Therefore, almost all recoveries from advanced loss of control involve something to do with regaining lift symetry over the airfoil.
You asked if the recovery was immediately available. That depends on how quickly the airfoil will establish itself towards something that resembles a spin, the faster this occurs the faster it can be recovered. In the case of the F-14 (the only fast jet that I know), this would be further a problem due to the variable geometry. At high wing sweep the mass concentration was very much aft, making the machine highly susceptible to tumbling for a while, the associated reduced wing area could possibly veer the aircraft directly into a flat spin, making it unrecoverable unless engines where still producing thrust. The good news is that a high sweep meant high speed, therefore the dart profile and associated high speed would tend to push the nose forward and help stabilize a potential spin.
Almost all departures from normal flight will result on the short or long term in the development of a spin, or an asymetry of lift over the wingspan. Sometimes the loss of control may bipass this phase and settle directly into a flat spiral, but often the initial tumbling will naturally get the machine steadily turning and establish it into the common spin. A more serious problem is when the departure follows a path which might be directly opposing gravity, here in that case there is very little forecast into saying what will happen, and physics might apply in mysterious ways here. Therefore, almost all recoveries from advanced loss of control involve something to do with regaining lift symetry over the airfoil.
You asked if the recovery was immediately available. That depends on how quickly the airfoil will establish itself towards something that resembles a spin, the faster this occurs the faster it can be recovered. In the case of the F-14 (the only fast jet that I know), this would be further a problem due to the variable geometry. At high wing sweep the mass concentration was very much aft, making the machine highly susceptible to tumbling for a while, the associated reduced wing area could possibly veer the aircraft directly into a flat spin, making it unrecoverable unless engines where still producing thrust. The good news is that a high sweep meant high speed, therefore the dart profile and associated high speed would tend to push the nose forward and help stabilize a potential spin.
QUOTE(Harmattan96 @ Sep 12 2009, 02:17 PM) 
You got my "Funny" answer via PM, here is the more serious one.
Almost all departures from normal flight will result on the short or long term in the development of a spin, or an asymetry of lift over the wingspan. Sometimes the loss of control may bipass this phase and settle directly into a flat spiral, but often the initial tumbling will naturally get the machine steadily turning and establish it into the common spin. A more serious problem is when the departure follows a path which might be directly opposing gravity, here in that case there is very little forecast into saying what will happen, and physics might apply in mysterious ways here. Therefore, almost all recoveries from advanced loss of control involve something to do with regaining lift symetry over the airfoil.
You asked if the recovery was immediately available. That depends on how quickly the airfoil will establish itself towards something that resembles a spin, the faster this occurs the faster it can be recovered. In the case of the F-14 (the only fast jet that I know), this would be further a problem due to the variable geometry. At high wing sweep the mass concentration was very much aft, making the machine highly susceptible to tumbling for a while, the associated reduced wing area could possibly veer the aircraft directly into a flat spin, making it unrecoverable unless engines where still producing thrust. The good news is that a high sweep meant high speed, therefore the dart profile and associated high speed would tend to push the nose forward and help stabilize a potential spin.
Almost all departures from normal flight will result on the short or long term in the development of a spin, or an asymetry of lift over the wingspan. Sometimes the loss of control may bipass this phase and settle directly into a flat spiral, but often the initial tumbling will naturally get the machine steadily turning and establish it into the common spin. A more serious problem is when the departure follows a path which might be directly opposing gravity, here in that case there is very little forecast into saying what will happen, and physics might apply in mysterious ways here. Therefore, almost all recoveries from advanced loss of control involve something to do with regaining lift symetry over the airfoil.
You asked if the recovery was immediately available. That depends on how quickly the airfoil will establish itself towards something that resembles a spin, the faster this occurs the faster it can be recovered. In the case of the F-14 (the only fast jet that I know), this would be further a problem due to the variable geometry. At high wing sweep the mass concentration was very much aft, making the machine highly susceptible to tumbling for a while, the associated reduced wing area could possibly veer the aircraft directly into a flat spin, making it unrecoverable unless engines where still producing thrust. The good news is that a high sweep meant high speed, therefore the dart profile and associated high speed would tend to push the nose forward and help stabilize a potential spin.
Thanks Harmattan - much appreciated.
So that doing this
http://www.youtube.com/watch?v=2uh4yMAx2UA
will not become this. . .
http://www.youtube.com/watch?v=Ca385XKYEnc...feature=related
This is the situation I was talking about. . .
http://www.youtube.com/watch?v=2uh4yMAx2UA
will not become this. . .
http://www.youtube.com/watch?v=Ca385XKYEnc...feature=related
This is the situation I was talking about. . .
After seeing that last video I can start speculating on a few things.
The first recovery from the rolls looked flimsy, poor accuracy on the recovery of bank . The second one goes overboard with this wonderful recovery at some frightfully low altitude. Both of them having displayed a tendency for instability on the longitudinal axis, I am willing to bet that there is some more load on one wing, and as soon as the roll is established centripetal force just accentuates the issue. It is also possible that the whole purpose of this sortie was to show the instability when flying with an uneven ordinance load. My combat aerodynamic knowledge is limited but, that is what this resembles heavily. It is a combat problem as after a few weapons have been deployed an aircraft can become very vulnerable in a turning fight because of his wing imbalance.
The first recovery from the rolls looked flimsy, poor accuracy on the recovery of bank . The second one goes overboard with this wonderful recovery at some frightfully low altitude. Both of them having displayed a tendency for instability on the longitudinal axis, I am willing to bet that there is some more load on one wing, and as soon as the roll is established centripetal force just accentuates the issue. It is also possible that the whole purpose of this sortie was to show the instability when flying with an uneven ordinance load. My combat aerodynamic knowledge is limited but, that is what this resembles heavily. It is a combat problem as after a few weapons have been deployed an aircraft can become very vulnerable in a turning fight because of his wing imbalance.
QUOTE(Harmattan96 @ Sep 12 2009, 07:45 PM)
After seeing that last video I can start speculating on a few things.
The first recovery from the rolls looked flimsy, poor accuracy on the recovery of bank . The second one goes overboard with this wonderful recovery at some frightfully low altitude. Both of them having displayed a tendency for instability on the longitudinal axis, I am willing to bet that there is some more load on one wing, and as soon as the roll is established centripetal force just accentuates the issue. It is also possible that the whole purpose of this sortie was to show the instability when flying with an uneven ordinance load. My combat aerodynamic knowledge is limited but, that is what this resembles heavily. It is a combat problem as after a few weapons have been deployed an aircraft can become very vulnerable in a turning fight because of his wing imbalance.
The first recovery from the rolls looked flimsy, poor accuracy on the recovery of bank . The second one goes overboard with this wonderful recovery at some frightfully low altitude. Both of them having displayed a tendency for instability on the longitudinal axis, I am willing to bet that there is some more load on one wing, and as soon as the roll is established centripetal force just accentuates the issue. It is also possible that the whole purpose of this sortie was to show the instability when flying with an uneven ordinance load. My combat aerodynamic knowledge is limited but, that is what this resembles heavily. It is a combat problem as after a few weapons have been deployed an aircraft can become very vulnerable in a turning fight because of his wing imbalance.
Thanks Harmy, I appreciate your time. I thought about the above and therefore searched more and indeed found it demonstrated at a testing squadron in the states. Where they purposely put an F-16 into this very same situation on purpose - and guess what. . ? you are right - it is caused by Yaw on an imbalance aircraft due to assymetric loading due to half the stores having been used from one wing. Kewel !!! (well maybe not so cool for the pilots)
Also, unrelated and on a sort of mystic level - or Cosmic. One of the videos I recently sent of F-16 HUD demo landings in peace. Well, the voice of the guy, all laid back and all was the same voice in the real life uncool scenarion of the F-16 being painted by sams. Hmmm. . .seems he made it back to fly another day.
Lordy, Lordy when they all come home we`ll have a pint or three.
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.