Cushioning of elevator horns against end stops?

[Pilottonny]

Hello,

While I am waiting for my Whirlwind propeller (a very long time!) I tranfered from the FWF to installing the tail feathers, and came across a thing I find strange: The elevator horns (steel powder coated) hit against the end stops (aluminum angles) without any protection. This will damage the powder coating on the horns and whatever coating is on the end stops and allow corrosion to do its devastating work. I figured that I could protect those angles with some rubber edge-protecting-strips. However, this will reduce the up/down-elevator movement by a few degr.

- Is this tolerable? (do you need every last ? of up- or down control??)
- Has anybody done this before?
- Should I not bother and just let it bang together, ?that?s just how it works?!?

Thanks in advance for your replies. Regards, Tonny.

 

[Kyle Boatright]

That's how it works. You don't bang the controls against the stops very often in an RV. If you are concerned about it, you could apply a strip of tape over the elevator horns to protect the paint.

Personally, I have used a modeling brush from time to time to touch up the paint on the elevator horns to prevent rust. There is just enough room through the inspection port to do that..

 

[mike109g6]

Elevator Stops

Tonny,

Sounds like you have never flown in a 9 - is that correct? If you ever hit the stops while flyiing you will have more to worry about than paint chips. Normal movement of the stick to achieve normal attitude deflection is an inch or two at most. That transmits to elevator horn deflection way below the stops, I doubt if you will ever touch the stops during the life of the plane. Remember, RV's do not respond like a Piper or Cessna. They are pretty responsive to stick inputs. During transition training you will appreciate what I mean.

Hope that this helps,
Mike H 9A/8A SOLD

 

[roee]

... I doubt if you will ever touch the stops during the life of the plane.

I disagree. You shouldn't be hitting the stops during cruise flight, but...

During your pre-takeoff checks for every flight you should manipulate the flight controls through their full range of motion, stop to stop, to verify that they are free and correct. That's pretty much standard practice in any airplane.

Also, full control deflections are routinely used for taxiing under different wind conditions, and for a variety of takeoff and landing techniques.

 

[L.Adamson]

I disagree. You shouldn't be hitting the stops during cruise flight, but...

During your pre-takeoff checks for every flight you should manipulate the flight controls through their full range of motion, stop to stop, to verify that they are free and correct. That's pretty much standard practice in any airplane.

Also, full control deflections are routinely used for taxiing under different wind conditions, and for a variety of takeoff and landing techniques.

In reality; your ailerons are most likely going to require an extra shove against your legs and possibly the seat cushions to get full deflection. And once you start flying your plane, you'll find that you only use of fraction of the total aileron deflection, even for tight banking turns.

But, as standard practice, I push my stick through full deflections before I even get in to the plane, to make sure the movement is as free and easy as usual.

I don't feel that there is a need for cushioning of the stops, as everything is actually quite balanced when all connected. I usually strap the stick with the seat belt if leaving the plane for extended times on the ramp....for wind.

edit...... this all applies to the 9 also. Since most of my RV hours were in two different 9A's before the six.

L.Adamson --- RV6A (flying)

 

[Pilottonny]

Cushioning is prefered!

A few things I learned from the replies and thinking things over:

• Full deflection is only used during taxi, so one or two ? less elevator travel will not matter very much.
• When the horns hit the stops, the coating wil be damaged.
• During pre-flight checks, the stops will be hit, to test and assure free and correct controls. (that is what I do now, in the spam cans of our club, when I do pre-flight).
• Wind should not be the cause of a stop-hit, because I should use a gust lock to prevent this, right? But,.... well..... sometimes..... a very short stop....... no wind........ and then..... a sudden gust..... you know what I mean!
• If the stops are cushioned there will be less stress on the horns, stops, elevators, push rod, etc. etc. if the horns actually do hit the stops.

So I tried to put some rubber strip on, that I had laying about, but it was to small for the total thicknes. And I guess a larger strip will not work, because of the rivets in the angle. I will have to think about this for a while, or maybe somebody else will chime in with an idea, or has already done something like this.

Regards, Tonny.

 

[rvbuilder2002]

A properly executed landing will have you typically using the full up elevator stop (hold the nose wheel off).
I personally would not want to give up any of the up elevator travel (available elevator effectiveness). You would be giving up the ability to flair at a slow airspeed with a more fwd C.G., which would force you to land faster. Not exceptable in my opinion.

 

[Bill Wightman]

Rubber control horn cushions in RV8

Tonny, I also like the idea of cushioned control stops, and figured out how to do it easily in the RV8. This might/might not work for your 9, but I offer it as an idea anyway:

I used short pieces of 1/2" OD rubber hose, cut length-wise through one side only. They are then slipped over the aluminum edges that the control horn bangs up against, and simply secured with safety wire. Real easy to do.

You can see the UP elevator stop in the picture, left side. There's also one for the Down stop.

With these stops in place, I still have +26 and -22 degrees of elevator travel, more than enough for everything I'll ever do with the airplane and within the recommended travel limits for the RV8 (limits given in the assembly manual).

 

[noelf]

It seems...

... that you could use some of the UHMW sticky tape on the elevator horn flange to provide a cushion effect with minimal disturbance to the elevator travel measurements.