Loss of dynamic stability on takeoff

[Pavlin_33]

Sometimes when pulling a bit harder on the stick during takeoff the plane, carrying 100% and 4×27 with 2×73, is not stable any more and it's very difficult to control. It's as if that override switch was flipped.

Has this happened to anyone else, or am I the only one?

Unfortunately I can't replicate this one in single-player (tried over 20 times), but happens to me in miltiplayer every now and then.

How to replicate:

- full AB

- full aft stick at around 250-260km/h

[Pavlin_33]

Best I can do at the moment is provide the TacView, but I am not sure how helpful it is. Just after takeoff, you can see the pitch wobble starting.
I am running stock DCS except for FC3 clickable mod - I wonder if that might have anything to do with it.

di.zip.acmi

[Wyvern]

That's because the plane is heavy. Under those conditions.
60% fuel would be a normal fuel load, while 100% fule is comparable to an F-16 or F-18 with extra Fuel tanks.



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[Pavlin_33]

2 minutes ago, Wyvern said:

That's because the plane is heavy. Under those conditions.
60% fuel would be a normal fuel load, while 100% fule is comparable to an F-16 or F-18 with extra Fuel tanks.



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I am not sure what do you mean by that. Because the airframe is heavy sometimes the stability augmentation fails?

[Wyvern]

A thing you can do (what I do to have a more stable takeoff)
Once you rotate and get off the ground, push the stick forward for a fraction of a second (as if youre counter steering in a car)
If done right, you should have lower AoA after take off, and a (very) slightly faster acceleration

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[Pavlin_33]

1 minute ago, Wyvern said:

A thing you can do (what I do to have a more stable takeoff)
Once you rotate and get off the ground, push the stick forward for a fraction of a second (as if youre counter steering in a car)
If done right, you should have lower AoA after take off, and a (very) slightly faster acceleration

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I've removed the Mod in hope that this was the cause of the issue.
I usually don't have any issues taking the Flanker into the air with full fuel tanks, but every now and then when I over-rotate this happens and I can't seem to figure out why.
It's literally like I have flipped that override switch. I happens maybe 1 out of 10 takeoffs. My last sortie I've ended up breaking the wings.

[Ironhand]

Are, by any chance, stalling the airframe?

[Irisz]

During takeoff, there is no limit on how far you can pull the joystick back! Full afterburner, pull the joystick all the way back, roll, and watch the Flanker's nose as it lifts. When the Flanker starts lifting its nose off the runway, maintain a maximum pitch angle of +10 degrees (at this point, push forward the joystick a bit to prevent the engine nozzle from touching the runway), take off from the runway, retract the landing gear, and enjoy the Flanker love!

 

This procedure lifts the nose up the Flanker off the runway depending on the weight! If your weight is low, sooner, if your weight is high, later, this keeps the pilot and the Flanker safe!

Don't try this at Fulcrum!

Su-27 special take off technique youtube video

At 2:50 you can see this technique I was talking about!

Edited May 21, 2024 by Irisz

[Pavlin_33]

On 5/20/2024 at 1:28 PM, Ironhand said:

Are, by any chance, stalling the airframe?

I don't think so, as that would require an enormous amount of pitch up.

It has not happened since I have removed the clickable cockpit mod, but I have not flown it much either.