Elevator/Rudder flutter

[CT]

Has anyone experienced high speed elevator/rudder flutter. Yesterday while flying my Viper I made a high speed pass and one half of the elevator ripped off, luckily was still able to control enough for a landing. Be aware that all the conrtol surfaces on the Viper are foam, and now I am replacing the surfaces with pin hinges, especially the elevator.
Also noticed this flutter on the Yak 130 while making an aggressive climb out of a low high speed pass. Although the Yaks surfaces are hinged, the visible flutter was quite alarming seeing the elevator flutter like thin paper. 
CT

[Pheonix]

RE: Elevator/Rudder flutter

I use Foam-tac on all my foam hinges.  Take some Foam-tac and run some the entire length of hinge and use a epoxy stick to spread it out evenly.  I have yet to have one fail or come loose using this simple technique.  I have not had this issue with pin hinges.

[PappaBear]

RE: Elevator/Rudder flutter

Control surface futter is nothing new, it was discovered in the early days of flight. But no one knew how to prevent it or how to stop it until the first world war. Its a really interesting thing to watch in slow motion actually, and once it starts the only way yo stop it is to slow the speed of the aircraft. Reduce power immediately and if possible raise the nose of the aircraft. If you still have control land.

The best way to prevent it is to balance the control surface with a mass balance forward of the hinge line. it doesn't take much, but its a great help.

Make sure the control linkages and control horns have no slop or play. If you have any free movement in the control surface it should be rectified. If you have wear in the servo gears, either replace the servo or the gears.

[CT]

RE: Elevator/Rudder flutter

Control surface futter is nothing new, it was discovered in the early days of flight. But no one knew how to prevent it or how to stop it until the first world war. Its a really interesting thing to watch in slow motion actually, and once it starts the only way yo stop it is to slow the speed of the aircraft. Reduce power immediately and if possible raise the nose of the aircraft. If you still have control land.

The best way to prevent it is to balance the control surface with a mass balance forward of the hinge line. it doesn't take much, but its a great help.

Make sure the control linkages and control horns have no slop or play. If you have any free movement in the control surface it should be rectified. If you have wear in the servo gears, either replace the servo or the gears.

Makes sense, I had added 2 cf strips to the underside of the elevators behind the hinge line for rigidity, which added weight and may have propagated the flutter.

[Sky Wolf]

RE: Elevator/Rudder flutter

Has anyone experienced high speed elevator/rudder flutter. Yesterday while flying my Viper I made a high speed pass and one half of the elevator ripped off, luckily was still able to control enough for a landing. Be aware that all the conrtol surfaces on the Viper are foam, and now I am replacing the surfaces with pin hinges, especially the elevator.
Also noticed this flutter on the Yak 130 while making an aggressive climb out of a low high speed pass. Although the Yaks surfaces are hinged, the visible flutter was quite alarming seeing the elevator flutter like thin paper. 
CT

By Viper, do you mean the Taft/EPIC/HSD? Or are you referring to the F-16 (also known as the Viper)?

[CT]

RE: Elevator/Rudder flutter

Has anyone experienced high speed elevator/rudder flutter. Yesterday while flying my Viper I made a high speed pass and one half of the elevator ripped off, luckily was still able to control enough for a landing. Be aware that all the conrtol surfaces on the Viper are foam, and now I am replacing the surfaces with pin hinges, especially the elevator.
Also noticed this flutter on the Yak 130 while making an aggressive climb out of a low high speed pass. Although the Yaks surfaces are hinged, the visible flutter was quite alarming seeing the elevator flutter like thin paper. 
CT

By Viper, do you mean the Taft/EPIC/HSD? Or are you referring to the F-16 (also known as the Viper)?

Taft Viper, I have applied Foam tac to all my foam hinges, seems the way to go on this problem

[Sky Wolf]

RE: Elevator/Rudder flutter

Has anyone experienced high speed elevator/rudder flutter. Yesterday while flying my Viper I made a high speed pass and one half of the elevator ripped off, luckily was still able to control enough for a landing. Be aware that all the conrtol surfaces on the Viper are foam, and now I am replacing the surfaces with pin hinges, especially the elevator.
Also noticed this flutter on the Yak 130 while making an aggressive climb out of a low high speed pass. Although the Yaks surfaces are hinged, the visible flutter was quite alarming seeing the elevator flutter like thin paper. 
CT

By Viper, do you mean the Taft/EPIC/HSD? Or are you referring to the F-16 (also known as the Viper)?

Taft Viper, I have applied Foam tac to all my foam hinges, seems the way to go on this problem

I love the Taft Viper! Same one I have. Haven't had any servo or flutter issues though. Glad you got her fixed.

[CT]

RE: Elevator/Rudder flutter

Has anyone experienced high speed elevator/rudder flutter. Yesterday while flying my Viper I made a high speed pass and one half of the elevator ripped off, luckily was still able to control enough for a landing. Be aware that all the conrtol surfaces on the Viper are foam, and now I am replacing the surfaces with pin hinges, especially the elevator.
Also noticed this flutter on the Yak 130 while making an aggressive climb out of a low high speed pass. Although the Yaks surfaces are hinged, the visible flutter was quite alarming seeing the elevator flutter like thin paper. 
CT

By Viper, do you mean the Taft/EPIC/HSD? Or are you referring to the F-16 (also known as the Viper)?

Taft Viper, I have applied Foam tac to all my foam hinges, seems the way to go on this problem

I love the Taft Viper! Same one I have. Haven't had any servo or flutter issues though. Glad you got her fixed.

The Viper I maidened was modded with a Dr Thrust 1000kv motor and running on 10s, obviously the airframe stock set up needs some fine tuning to handle the extra loads and speeds

[Sky Wolf]

RE: Elevator/Rudder flutter

Has anyone experienced high speed elevator/rudder flutter. Yesterday while flying my Viper I made a high speed pass and one half of the elevator ripped off, luckily was still able to control enough for a landing. Be aware that all the conrtol surfaces on the Viper are foam, and now I am replacing the surfaces with pin hinges, especially the elevator.
Also noticed this flutter on the Yak 130 while making an aggressive climb out of a low high speed pass. Although the Yaks surfaces are hinged, the visible flutter was quite alarming seeing the elevator flutter like thin paper. 
CT

By Viper, do you mean the Taft/EPIC/HSD? Or are you referring to the F-16 (also known as the Viper)?

Taft Viper, I have applied Foam tac to all my foam hinges, seems the way to go on this problem

I love the Taft Viper! Same one I have. Haven't had any servo or flutter issues though. Glad you got her fixed.

The Viper I maidened was modded with a Dr Thrust 1000kv motor and running on 10s, obviously the airframe stock set up needs some fine tuning to handle the extra loads and speeds

10s...nice! 

[Rocketeer]

RE: Elevator/Rudder flutter

Greetings CT,

Are you using a stabilizer (AS3X or similar)?



Bill L.
In Okla.

[CT]

RE: Elevator/Rudder flutter

Greetings CT,

Are you using a stabilizer (AS3X or similar)?



Bill L.
In Okla.

Hi Bill,
I use the AS3X in my 3d birds but have not flown my EDF"s with one. To tell you the truth, the large birds, 12s super viper, 9s Yak130, and others are so rock steady and stable they fly like trainers anyway. I could imagine it would be useful in windy conditions like my 1700 B-17, which is so light it literally flies like a glider. In general I do not like to fly in wind though, nothing flies like scale and I find it's just not fun.
CT

[Rocketeer]

RE: Elevator/Rudder flutter

Greetings CT,

I just thought I'd ask as elev/rudd flutter is quite common on planes that incorporate stabilization at high speeds due to the units inability to compensate quickly enough. 

The only other instance I have heard of is if/when the Horizontal/Vertical Stab assembly is out of square.

I have seen this flutter issue on some of the aerobatic aircraft at our field.
It's really weird.

I hope you find a resolution.

Clear Skies

Bill L.
In Okla.