Rudder system failure

[Nick Kennedy]

After the Arcus rudder failure in Nephi this summer, and the Early JS1 rudder failure in Moriarty, both resulting in bailouts; I've been wondering.....
In a 15 meter ship like a ASW 20 or LS3a or ASW27, does a hard over rudder failure mean its bailout time, or is it possible to "catch" the ensuing turn with the ailerons.
Or is it best to get out quick before you get pinned in the cockpit due to the increasing G forces.
Would it be landable on a airport?
Does wingspan effect the equation?
I've been meaning to try this in my LS3a, but its in the shop, soaking up hundred dollar bills.
By trying this, I mean see if I can fly it straight with one rudder pinned to the floor for a extended period of time, and make some gentle turns.
any thoughts?

[[email protected]]

I will ask Fidel to glue your rudder to one side. Let us know how it goes.

ps. would you prefer left or right?

[Ramy[_2_]]

I think the answer is it depends. You can certainly fly in full slip with the rudder pedal fully pressed. But if the glider already entered a spin i doubt you can recover with aileron.
The landing will be “interesting” in full slip. I think best case scenario is ground loop...
I hope to never have to find out...

Ramy

[Eric Munk]

In some types opening airbrakes reduces rudder effectiveness in sideslip,
allowing for more control with ailerons. Had a Puchacz with a broken cable
turnbuckle that was landed that way.

[kinsell]

Do you know for a fact it was a rudder failure? JJ Sinclair had an
interesting post about the vertical fin stalling on a Nimbus 3, and the
dirty air behind it causing the rudder to go hard over.



On 08/27/2018 05:23 PM, Nick Kennedy wrote:
> After the Arcus rudder failure in Nephi this summer, and the Early JS1 rudder failure in Moriarty, both resulting in bailouts; I've been wondering.....
> In a 15 meter ship like a ASW 20 or LS3a or ASW27, does a hard over rudder failure mean its bailout time, or is it possible to "catch" the ensuing turn with the ailerons.
> Or is it best to get out quick before you get pinned in the cockpit due to the increasing G forces.
> Would it be landable on a airport?
> Does wingspan effect the equation?
> I've been meaning to try this in my LS3a, but its in the shop, soaking up hundred dollar bills.
> By trying this, I mean see if I can fly it straight with one rudder pinned to the floor for a extended period of time, and make some gentle turns.
> any thoughts?
>

[Nick Kennedy]

Dave
I'm not 100% sure but I think both accidents were caused by a rudder cable coming apart and then the springs in the system pins the rudder hard over.
In most gliders when this occurs I don't the pilot can correct the rudder hard over situation.

[James Betker]

On Tuesday, August 28, 2018 at 4:25:39 AM UTC-7, kinsell wrote:
> Do you know for a fact it was a rudder failure? JJ Sinclair had an
> interesting post about the vertical fin stalling on a Nimbus 3, and the
> dirty air behind it causing the rudder to go hard over.
>
>
>
> On 08/27/2018 05:23 PM, Nick Kennedy wrote:
> > After the Arcus rudder failure in Nephi this summer, and the Early JS1 rudder failure in Moriarty, both resulting in bailouts; I've been wondering.....
> > In a 15 meter ship like a ASW 20 or LS3a or ASW27, does a hard over rudder failure mean its bailout time, or is it possible to "catch" the ensuing turn with the ailerons.
> > Or is it best to get out quick before you get pinned in the cockpit due to the increasing G forces.
> > Would it be landable on a airport?
> > Does wingspan effect the equation?
> > I've been meaning to try this in my LS3a, but its in the shop, soaking up hundred dollar bills.
> > By trying this, I mean see if I can fly it straight with one rudder pinned to the floor for a extended period of time, and make some gentle turns.
> > any thoughts?
> >

Along those lines - what causes a rudder to fail full lock?

[JS[_5_]]

On Tuesday, August 28, 2018 at 9:32:18 AM UTC-7, Nick Kennedy wrote:
> Dave
> I'm not 100% sure but I think both accidents were caused by a rudder cable coming apart and then the springs in the system pins the rudder hard over.
> In most gliders when this occurs I don't the pilot can correct the rudder hard over situation.

In single-seat gliders this is probably the case. In two-seaters there is another set of pedals.
Seems that most rudder cable failures have been at the S-tube of the front seat (or only seat) rudder pedals. If there's another occupied seat, the other set of pedals should still be working but with more resistance on one side.
Funny... James posted at the same time as Nick answered his question.
Jim

[Bob Kuykendall]

During my last BFR, we practiced rudder hardover maneuvers in the ASK21. We explored the high-sideslip flight regime in which the rudder would remain against its stop on its own until pulled towards center with the opposite pedal.

The point of the exercise was to demonstrate how it could be a surprise if you weren't prepared for it, but that it was not very hazardous in and of itself. "Hardover" is kind of a misnomer; the forces required to pull the rudder off the stop are relatively modest.

The rudder pedal return springs in most gliders are fairly weak, and I rather doubt that they would put you into a hardover on their own. However, if you're flying around with 50 lbs of pressure on each pedal and one of the cables breaks, that might do it, depending on a variety of factors.

Of course, combining a hardover sideslip with a rudder control failure could be very problematic, and I'm not sure what the most appropriate response would be. In the moment, I think I'd explore using adverse yaw to get the rudder off the stop, at least to the degree allowed by altitude.

I'm still waiting to see what the NTSB report says about the Arcus accident.. Dave will tell us about it when he's ready.

--Bob K.

[Nick Kennedy]

Update
So I got a call from a friend that the Nephi accident cause is still undetermined.
Sorry for the possible mis- information. I was there at the event and that is what I heard on the ramp, But Bob is right.
Lets let the NTSB come out with its findings.
Thank you