SonexBuilders.net

Has anyone (or is anyone planning to) done the modification to the horizontal stabilizer tip fairings to attach them where they can be removed?

Here is one builders example http://www.pbase.com/sonex293/image/36268625

Basically a strip is riveted where the stabilizer tip is normally riveted, and nutplates are installed on the strip. Flush screws are used as attachments.

Makes sense to me, as the tips can be removed to paint or to inspect inside the tail using a borescope. I am trying to keep the modfications to a minimum, but this one looks straightforward.

Opinions? Anyone done this or going to do it?

We're thinking we will do it - have a friend (our safety counselor) who is an A&P/IA also and is going to assist us in making it right....


Robbie Culver
Sonex 1517
Chicagoland
Aerovee/taildragger
Starting on the wings
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I just can't see any benefit to this...I just don't see much need to remove the tail tips. I even made my tips from scratch, so I've already put extra effort into them, but I have no desire to remove them once mounted. The tail on the Sonex is pretty robust...so I guess you have to ask yourself how often, if ever, you are going to want to inspect the interior of the tail. If I have any need to inspect, I will just drill out the rivets ( you can even use aluminum rivets to make the task easier). If you plan on doing it frequently, you may need removable tips.

Frank
Sonex #800 - Scratch Building

Personally, the answer to "how often" is once a year. During the condition inspection.


Robbie Culver
Sonex 1517
Chicagoland
Aerovee/taildragger
Starting on the wings
Sent from my iPad using Tapatalk

I thought about doing this, but decided there is no real benefit (to me). Once it's put together, the tail is kind of a black box; there's no real reason to look in there since any problems will likely have some external sign. If you live near an ocean or other corrosive environment, it might make more sense, and of course if you had something in there like a pitot line or antenna then it makes perfect sense.

In doing the removable tips you gain access, but are adding complexity. If things vibrate free you can lose a tip, whereas with the stock setup you'd have to unwrap a whole control surface for the tip to come free.

I did this but only because I found it too difficult to wedge the tail tip under the skin.
This is much easier.

What thickness aluminum did you use? Thanks for the reply! Poking around on your build log now....


Robbie Culver
Sonex 1517
Chicagoland
Aerovee/taildragger
Starting on the wings
Sent from my iPad using Tapatalk

Yeah, I agree getting the tips under the skin is problematic (especially if you plan on removing the tips). What I did (and would recommend) is that I made my the width of my end ribs on both stabilizers overall about 1/16" less than what the plans showed. With this mod, I had had no problem getting the tips under the skin.

- Frank
Sonex #800 - Scratch Building

rizzz wrote:I did this but only because I found it too difficult to wedge the tail tip under the skin.
This is much easier.

That is truth! I think I gained some great arm strength getting those tips in.

Sonex1517 wrote:What thickness aluminum did you use? Thanks for the reply! Poking around on your build log now....


Robbie Culver
Sonex 1517
Chicagoland
Aerovee/taildragger
Starting on the wings
Sent from my iPad using Tapatalk

I used 0.032.
Wedges in much easier than the thick fibreglass tips.

I think if you'd really want to fit the tips under the skin nicely, you'd be better off making the tip rib slightly undersized, and to make life even easier you'd put the tail tip in place before riveting tail skin.

With the current procedure in the plans you really notice that the tail tips are something that Sonex added to their original design at a later stage.
If they had had the tips there from the beginning, I suspect they would have put something similar in the plans as I describe above.

I used a method that another builder Dave Clay did. I took an additional tip and riveted upside down with the flanges facing out to attach the tip to. I made my tips from scratch so maybe they were a little thicker than the Sonex Tips, but I could not wedge them between the skin and rib. I screwed my tips on to the additional rib, but they can be riveted just as well.