10-18-2008, 11:11 AM
Here is how it described his Cobra manoeuver, ten years ago (1998) in Aeroworldnet.com :
Week of August 10, 1998
An Interview With Sukhoi's Famed Cobra Test Pilot , by Vovick Karnozov.
(...)
Q. There is a maneuver carrying your name, "Pugachev's Cobra." How was it invented?
In 1988, when a decision was made that Sukhoi should participate at Paris'89, we began thinking what we should do to make our participation exceptional, so as to show the world what the "Su" mark is worth. Preparation begun in earnest a year before the show. At that time our company was involved in a vast program of super-agility investigations, during which we discovered that the Su-27 had very special capabilities which we had never known before and which had never been observed on any other aircraft in the whole world. Calculations, modeling, flights on the flight simulator revealed that the Su-27 can perform "super-maneuvers" at high angles of attack (alpha), such as a quick pitch turn, up to 90-110 degrees alpha.
At that time I was performing the final part of the flight-test program to investigate deep stall on the Su-27. At the end of this part, we naturally began trying "super-maneuvers" at very high alpha. The first was the "Bell" or "Tail Slide" (when the aircraft climbs at a high angle without power, reduces the speed down to zero in a nose-up position and then slides on its tail). Here we had no problem, because many of our aircraft had done it before. Then we began thinking of a next maneuver, "Dynamic Deceleration," which is now called the "Cobra." The idea was that the aircraft would make a quick pitch-up turn in an effort to aim with its nose at the hostile aircraft flying above it. Such a maneuver could also be handy as a defensive action when the hostile aircraft is on the tail. In the latter case we could make a sharp evasive action coupled with extensive deceleration.
In the spring of 1989 we came to a stage when it was possible to try to execute this maneuver. Our team was obsessed with it. We were feeling that just one more effort and we would have it done and that would be something worth showing at Paris'89. Of course, we could restrict ourselves to showing a very accurate display flight, doing it better than anybody else, but it would not be as interesting to aviation specialists because it would carry nothing new to them. And we decided that "Dynamic Deceleration" is something worth putting on the top, something that would make our display flights distinguishable to specialists, because nobody else could do it.
The idea came over together with lots of difficulties in terms of its materialization. In normal configuration, the aircraft was not stable enough while executing the maneuver. To cope with it, we had to introduce some design changes, including installation of vortex generators on the Pitot tube. This helped and I began trying this maneuver at high altitudes, gradually getting down to 800-1000 m, where the aircraft is visible from the ground. On 25 April I demonstrated this maneuver to a group of employees of our design bureau over the airdrome in Zhukovsky.
Q. This maneuver breaks classic understanding of aerodynamic laws. Did you feel fear when trying it for the first time?
No, there was no fear. As I said, we began working at high altitudes, where we had tried deep stalls. Of course, test pilots always feel stress somewhere within themselves when they are about to try a new regime. The brain realizes that the aircraft should behave in an anticipated manner, but what if it doesn't? And this uncertainty cause the stress. But after the pilot has executed the first regime, he has a restored trust in the aircraft and the stress disappears. For the first time it is not necessary to do the maneuver perfectly, because that is not what matters. Once the first regime has been done, the test pilot will begin to do it again and again to make it work as required. It is something our job is all about.
In the case of the "Cobra" we soon found out that the aerodynamic control surfaces are not efficient to control the aircraft at low speeds and that it is necessary to employ thrust control. Different power settings for each of the two engines or a sort of thrust-vectoring. This idea came to the minds of the Sukhoi designers exactly during mastering the "Cobra" and "Bell" maneuvers on the Su-27. The thrust control system on the Su-37 has proved our expectations. Using thrust control methods, we gradually made the aircraft really capable of turning at slow speeds in different planes, which has led to the "Cobra" being executed in the horizontal plane instead of the vertical one. This new maneuver is called the "Hook."
The response of performing the "Cobra" at Paris'89 was great. Sukhoi did steal the show and from that moment on Sukhoi aircraft have been the most popular at many other international air shows that followed. As I mentioned before, the "Cobra" evolved into the "Hook," thus becoming a normal combat regime for aircraft with thrust-vectoring systems. In a sense, the "Cobra" was the first step to mastering super-agility. Our latest aircraft can maneuver effectively in all corners of the flight envelope, at all possible speeds, altitudes and angles of attack. "
(...)
Ch.
Pic : Arsenal - 03.2008
Week of August 10, 1998
An Interview With Sukhoi's Famed Cobra Test Pilot , by Vovick Karnozov.
(...)
Q. There is a maneuver carrying your name, "Pugachev's Cobra." How was it invented?
In 1988, when a decision was made that Sukhoi should participate at Paris'89, we began thinking what we should do to make our participation exceptional, so as to show the world what the "Su" mark is worth. Preparation begun in earnest a year before the show. At that time our company was involved in a vast program of super-agility investigations, during which we discovered that the Su-27 had very special capabilities which we had never known before and which had never been observed on any other aircraft in the whole world. Calculations, modeling, flights on the flight simulator revealed that the Su-27 can perform "super-maneuvers" at high angles of attack (alpha), such as a quick pitch turn, up to 90-110 degrees alpha.
At that time I was performing the final part of the flight-test program to investigate deep stall on the Su-27. At the end of this part, we naturally began trying "super-maneuvers" at very high alpha. The first was the "Bell" or "Tail Slide" (when the aircraft climbs at a high angle without power, reduces the speed down to zero in a nose-up position and then slides on its tail). Here we had no problem, because many of our aircraft had done it before. Then we began thinking of a next maneuver, "Dynamic Deceleration," which is now called the "Cobra." The idea was that the aircraft would make a quick pitch-up turn in an effort to aim with its nose at the hostile aircraft flying above it. Such a maneuver could also be handy as a defensive action when the hostile aircraft is on the tail. In the latter case we could make a sharp evasive action coupled with extensive deceleration.
In the spring of 1989 we came to a stage when it was possible to try to execute this maneuver. Our team was obsessed with it. We were feeling that just one more effort and we would have it done and that would be something worth showing at Paris'89. Of course, we could restrict ourselves to showing a very accurate display flight, doing it better than anybody else, but it would not be as interesting to aviation specialists because it would carry nothing new to them. And we decided that "Dynamic Deceleration" is something worth putting on the top, something that would make our display flights distinguishable to specialists, because nobody else could do it.
The idea came over together with lots of difficulties in terms of its materialization. In normal configuration, the aircraft was not stable enough while executing the maneuver. To cope with it, we had to introduce some design changes, including installation of vortex generators on the Pitot tube. This helped and I began trying this maneuver at high altitudes, gradually getting down to 800-1000 m, where the aircraft is visible from the ground. On 25 April I demonstrated this maneuver to a group of employees of our design bureau over the airdrome in Zhukovsky.
Q. This maneuver breaks classic understanding of aerodynamic laws. Did you feel fear when trying it for the first time?
No, there was no fear. As I said, we began working at high altitudes, where we had tried deep stalls. Of course, test pilots always feel stress somewhere within themselves when they are about to try a new regime. The brain realizes that the aircraft should behave in an anticipated manner, but what if it doesn't? And this uncertainty cause the stress. But after the pilot has executed the first regime, he has a restored trust in the aircraft and the stress disappears. For the first time it is not necessary to do the maneuver perfectly, because that is not what matters. Once the first regime has been done, the test pilot will begin to do it again and again to make it work as required. It is something our job is all about.
In the case of the "Cobra" we soon found out that the aerodynamic control surfaces are not efficient to control the aircraft at low speeds and that it is necessary to employ thrust control. Different power settings for each of the two engines or a sort of thrust-vectoring. This idea came to the minds of the Sukhoi designers exactly during mastering the "Cobra" and "Bell" maneuvers on the Su-27. The thrust control system on the Su-37 has proved our expectations. Using thrust control methods, we gradually made the aircraft really capable of turning at slow speeds in different planes, which has led to the "Cobra" being executed in the horizontal plane instead of the vertical one. This new maneuver is called the "Hook."
The response of performing the "Cobra" at Paris'89 was great. Sukhoi did steal the show and from that moment on Sukhoi aircraft have been the most popular at many other international air shows that followed. As I mentioned before, the "Cobra" evolved into the "Hook," thus becoming a normal combat regime for aircraft with thrust-vectoring systems. In a sense, the "Cobra" was the first step to mastering super-agility. Our latest aircraft can maneuver effectively in all corners of the flight envelope, at all possible speeds, altitudes and angles of attack. "
(...)
Ch.
Pic : Arsenal - 03.2008
