Anyone achieved a perfect cobra?

[rami80]

Has anyone been able to do a perfect cobra i.e. no altitude gain? Would love to see videos:D

 

Edit: Slight altitude gain. I keep getting 100+ meters.

Edited November 20, 2014 by rami80

[Thumper1606688436]

a perfect cobra i.e. no altitude gain

 

That's aerodynamically impossible.

[Buznee]

sure, just start in a dive first =) then the altitude you gain puts you back at the altitude you started hah. In all seriousness though Thumper is right. When you perform the cobra you increase angle of attack, increasing lift until you stall the wing. You can reduce the altitude gain by pulling sharply on the stick and getting into stall quicker. Be careful though because that means more G!

[Ironhand]

That's aerodynamically impossible.

 

Evidently this guy didn't get the memo:

 

 

In case the link doesn't work: Cobra

 

Watch the smoke trails between seconds 16 and 22.

 

I'll admit that, while it's a Flanker, it's not the one we have in the sim.

[mvsgas]

Evidently this guy didn't get the memo:

 

b-VNSJMiNt0

 

In case the link doesn't work: Cobra

 

Watch the smoke trails between seconds 16 and 22.

 

I'll admit that, while it's a Flanker, it's not the one we have in the sim.

 

So your saying that it is possible if we have thrust vectoring like the SU-35 prototype/tech demonstrator or like the SU-30MK series?

[NineLine]

Yeah look at the cobras in this vid, you can see altitude gains:

 

[Ironhand]

So your saying that it is possible if we have thrust vectoring like the SU-35 prototype/tech demonstrator or like the SU-30MK series?

Sorry. I just couldn't resist. :) Apparently, it is. I thought it was pretty cool. Every other video I've seen has had altitude gain. Some huge. Some not so much.

 

 

Rich

[Fri13]

I have seen video recorded from cockpit when next Su-27S (or SMK, without TV anyways) pulls cobra and the altitude gain is only about 10m or less when looking the position of thrusters nozzle level. Of course there is always a small altitude gain but it isn't "anything", like when F-22 pulls cobra it gains altitude dramatically and can't recover back to same altitude.

 

So when comparing Su-27 (Without TV) to others, it can do cobra without gaining altitude. It really is that it just raise the nowe , slow downs a little bit and then lowers nose back down.

[combatace]

Has anyone been able to do a perfect cobra i.e. no altitude gain? Would love to see videos:D

 

Edit: Slight altitude gain. I keep getting 100+ meters.

 

Sure there is no altitude difference from in and out of cobra but that means altitude exactly before entering the cobra and altitude after exiting the cobra i.e. you are now at level flight and with most of the speed gained back.

[esb77]

Evidently this guy didn't get the memo:

 

 

 

Watch the smoke trails between seconds 16 and 22.

 

 

There was definitely elevation gain when I watched them. Not much, hard to tell with the camera angle, maybe less than 15 m, almost certainly less than 50 m.

 

For an airshow performance as long as you have smoke off, gains of 10 or 15 m or so are going to be hard for spectators to detect, that's less than the length of the plane.

 

When it comes to quality of cobra maneuvers usually what I've seen in terms of criteria were: yaw control, roll control, maximum pitch achieved, and good recovery.

 

Ideally meaning no uncommanded yaw or roll, pitch of up to 130 to 135 degrees, and little to no loss of altitude during/after recovery.

 

I've had one really good cobra so far, I think I made about 125 degrees, but I didn't pay attention to altitude change, because none of the sources I used on how to perform the maneuver listed controlling altitude gain as a concern for proper execution.

[mazen]

hi

 

this is what i can do so far it is not perfect but i think it is good sorry for the bad video quality:joystick:

${1}

 

Edited November 21, 2014 by mazen

[NineLine]

Nice! One of the better ones I have seen!

[Ironhand]

this is what i can do so far it is not perfect but i think it is good sorry for the bad video quality...

 

 

Excellent! Hopefully I'll have some time this weekend to try my hand at it. Yours is the one to beat! :)

[rami80]

This is awesome! Could you maybe give us an outline of how you were able to achieve this?

[Smokin Hole]

Perfect cobra?

 

Nothing's perfect but mine look close to what I've in Su27/35 porn on the interwebs.

[mazen]

hi

 

This is awesome! Could you maybe give us an outline of how you were able to achieve this?

 

 

fly at speed of 390-400 km on the hud lower the thrust to idle then pull back the stick with pressing "s" key(fly assistance disable key) when the su-27 become vertical hit "s" again with pushing forward the stick and raise the thrust to 50% :joystick:

[theropod]

So your saying that it is possible if we have thrust vectoring like the SU-35 prototype/tech demonstrator or like the SU-30MK series?

 

this is the first prototype and had no trust vector till su-37 improved version which have movable up and down nozzles.

 

but there is another property look at the cobra manoeuvre starts different rotation at 1:30

http://www.youtube.com/watch?v=b-VNSJMiNt0

 

i think rudder seems more effective than our su-27. he can move aircraft with rudder at high angles and can turn it downwards.

 

i hope there will be a correction on next updates.

[rami80]

this is the first prototype and had no trust vector till su-37 improved version which have movable up and down nozzles.

 

but there is another property look at the cobra manoeuvre starts different rotation at 1:30

http://www.youtube.com/watch?v=b-VNSJMiNt0

 

i think rudder seems more effective than our su-27. he can move aircraft with rudder at high angles and can turn it downwards.

 

i hope there will be a correction on next updates.

 

Thank's for the directions Mazen, I'll try them in a while:D

 

Maybe it's because the su-27 in DCS doesn't kill enough speed during the cobra, if you notice after he does the hook his speed is very low.

[theropod]

Maybe it's because the su-27 in DCS doesn't kill enough speed during the cobra, if you notice after he does the hook his speed is very low.

 

yes maybe thats an issue,

rudders doesnt have enough affect to change direction for high alpha angles on low speeds.

maybe i am wrong but su-27's rudder has big movable control surface parts and this makes me to expect more effective on low speed manouevers.

Edited November 22, 2014 by theropod

[Weta43]

Part of a larger after flight report by a USN F-18 pilot who was taken up in an Su-27 by Anatoly Kvochur

 

We discussed the Cobra in our flight brief. It went something like this:

Me: "I would like you to show me the Cobra maneuver."

Kvochur: "Yes, sure."

Me: "What entry airspeed and altitude should we use?"

Kvochur extended the fingers of both hands in a calming gesture and said: "I show you."

That was it. I looked toward our interpreter for a read on this physical punctuation, but she returned the internationally universal shoulder shrug. So I took his brevity as an admonition against prying too much into this top-secret aerobatic phenomenon and made a mental note to be prepared to absorb as much technical data as I could during his demo.

When I was ready for the demo, he had me turn off the angle of attack limiter and another fly-by-wire switch that was never explained completely to me. Then he said, "I do one. We do one. You do one." The setup was 350 kilometers per hour (approximately 190 knots) in straight and level flight. He pulled the stick all the way back, and the airplane pitched nose up past vertical. In a little more than one second, we were more than 90 degrees nose up after the stick pull. He recovered the plane back to straight and level, and the maneuver was complete. The speed was about 90 knots as the nose approached the horizon. During the "We do one," I was again surprised at the non-aggressive control inputs. He used large pedal displacements during the first half of the pitch-up then transitioned to differential throttle control to keep the roll and yaw minimized. For the nose-down recovery, the stick was moved well forward but not all the way. Differential throttle that gave way to rudder-pedal activity essentially kept us wings-level throughout. My turn: I replicated what I had just ridden through, and the results were the same. I didn’t get past 90 degrees nose up like Kvochur, but I was awed anyway. Despite the radical attitude change, the entire maneuver was completed under 3G. Throughout this seemingly suicidal contortion, the engines never complained, and there was no implication of an impending loss of control.

Fun complete, I switched the limiter and fly-by-wire switches back to their normal positions, and we headed back.

 

So rudder to a point, then differential throttles...

[ShuRugal]

That's aerodynamically impossible.

 

tell that to these guys:

 

 

at 1:55 and again at 2:05, the pilot performs a Cobra with almost no visible altitude gain during the manuever, and ends the manuever at the same altitude he started it.

[Weta43]

You rally should change that to "almost no noticeable altitude gain during the manuever"

 

and then add -"if you're quite unobservant."

 

In both (all) of those cases shown - you can see the aircraft increase altitude during the manoeuvre.

[ShuRugal]

You rally should change that to "almost no noticeable altitude gain during the manuever"

 

and then add -"if you're quite unobservant."

 

In both (all) of those cases shown - you can see the aircraft increase altitude during the manoeuvre.

 

sure, less than the height of his own vertical stab. The altitude he "gained" during the first instance was certainly entirely negligible.

[Weta43]

Didn't look that way to me.

 

Particularly in the one at 2.05 if you look at the contrails as they disappear off screen he gains quite a bit of altitude - & then visibly dives to get back to his starting altitude.

 

All the other shots where you actually have a reference show significant altitude change (you're looking down on them, now you're looking up at them, etc.)

 

Even if it didn't look to me like they changed altitude, I'd find it more credible that the angle made it difficult to pick up than that if it can be done 'correctly' with no altitude change, then of all the 'cobra's' done, all but 1 or 2 were poorly exercised & gained altitude and they decided to include them anyway..

[ShuRugal]

All the other shots where you actually have a reference show significant altitude change (you're looking down on them, now you're looking up at them, etc.)

 

the reference point i was working from is the non-maneuvering aircraft. In the first execution (1:55) the tailpipe of the maneuvering aircraft does not pass above the tail of his wingman as he passes behind him. At the termination of the maneuver (nose comes back level), he is co-altitude with his wingman, as he was upon entering the maneuver.

 

I'm not sure how much closer to "zero/negligible elevation gained during maneuver" it is possible to achieve, but for a maneuver that lifts the nose 90 degrees above the horizon, i'd say an elevation gain of only 2-3 meters is pretty damn close to insignificant.