Tail Flutter...

[mytai01]

Observe the tail flutter as the F-15 pitches up...

 

https://www.facebook.com/share/r/1APWQHT9aU/

[SDsc0rch]

love it!

[mytai01]

I've seen a video of this flutter on the F-14, as well... It probably happens on all twin tail aircraft.

[mkellytx]

On 3/21/2025 at 4:48 PM, mytai01 said:

Observe the tail flutter as the F-15 pitches up...

 

https://www.facebook.com/share/r/1APWQHT9aU/

Sorry, that's just FBW rapid flight control movements.  Flutter is a totally different beast, it's self-excited, aeroelastic, by definition it's resonant in both bending and twisting, and with control surfaces in the best case is limited, less bad control surface falls off and worst-case wings or tails fall off.  The only flight tests I flew where the hair on the back on the neck stood up were the flutter tests.  We flew 20% past Vne, did stick raps and waited to see if the oscillations began.

[draconus]

4 hours ago, mkellytx said:

Sorry, that's just FBW rapid flight control movements.

Since when FBW can move whole vertical stabs laterally? Can it also flap wings?

Edited April 3 by draconus

[Bulldog_1]

9 hours ago, draconus said:

Since when FBW can move whole vertical stabs laterally? Can it also flap wings?

 mkellytex was looking at the horizontal stabilators, not the tails. I used to find cracks at the base of the vertical tails due to tail flutter, and I'm sure they still do today.

[mkellytx]

5 hours ago, Bulldog_1 said:

 mkellytex was looking at the horizontal stabilators, not the tails. I used to find cracks at the base of the vertical tails due to tail flutter, and I'm sure they still do today.

I've seen the vids of the F-15 verticals load limited flutter, but they're at high speed and G, not going around for a missed approach.

[doedkoett]

You guys are talking about different things. Flutter, in the aviation world is when a control surface starts to self-oscillate. This is a serious problem which can lead to the destruction of the control surface or wing. The aircraft resistance to flutter is thoroughly tested during development. This is what mkellytx is talking about.

The movement of the fins on the F-15 in the clip are merely vibrations, which itself can have a detrimental effect on the longevity of the airframe, but when the maneuver is ended the vibrations stop. If it was flutter, the fin might not stop shaking, and the oscillations might increase until the fin separates from the aircraft.

[Bulldog_1]

7 hours ago, doedkoett said:

The movement of the fins on the F-15 in the clip are merely vibrations, which itself can have a detrimental effect on the longevity of the airframe, but when the maneuver is ended the vibrations stop. If it was flutter, the fin might not stop shaking, and the oscillations might increase until the fin separates from the aircraft.

Good point! 

[mytai01]

On 4/2/2025 at 3:37 PM, mkellytx said:

Sorry, that's just FBW rapid flight control movements.  Flutter is a totally different beast, it's self-excited, aeroelastic, by definition it's resonant in both bending and twisting, and with control surfaces in the best case is limited, less bad control surface falls off and worst-case wings or tails fall off.  The only flight tests I flew where the hair on the back on the neck stood up were the flutter tests.  We flew 20% past Vne, did stick raps and waited to see if the oscillations began.

I wasn't talking about the rudder movement, I was talking about the shaking that can be observed at the tips of the tails.

[mytai01]

On 4/4/2025 at 4:24 AM, Bulldog_1 said:

Good point! 

Whatever the movement is called, it would be nice to see modelled at some point in the sim...

[Czar66]

2 hours ago, mytai01 said:

Whatever the movement is called, it would be nice to see modelled at some point in the sim...

The Strike Eagle has it.