Replies to This Discussion

Permalink Reply by Jonathan Porter on April 12, 2010 at 3:07am

Hmmm.... the H stab can be moved fore and aft during installation - I would think that you have enough play in the tolerances to adjust to get the right fit. Perhaps a photo of your challenge would help those with suggestions...

Do watch the electrolytic reactions between alu-stanless... especially on a structural and essential location!

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Permalink Reply by Einar Arne Kleiven on April 12, 2010 at 5:02am

Yes, you can move stab only forward with shimming between the aft brakket (that is going on the inside of the fuselagebrackets) and and the fuselagebracket.
It is not possible to move the stab further aft than when stopping on the aft bracket...
But this moving ( forward), will make it worse!!

Yes, I know that there is an issue about different metall joined together... but do priming, corrosion X, rinsing and care take some of the corrosion-speed away?
How many years together, before one can see corrosion ( and where will the weakest point bee? rivet?)

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Permalink Reply by Jacob on April 12, 2010 at 6:08am

The are some products available which are designed especially for fitting together disimilar metals e.g. aluminium and stainless steel etc. One of them is called duralac which comes in a big toothpaste tube and you just wipe it on your primed parts before assembly. Duralac dries and goes very hard. The other is called Mastenox (not sure if the spelling is correct) which comes in a corking gun style tube. Mastenox is yellow like duralac and at first seems the same but it does not go hard like duralac which is good if you ever want to disassemble a component again in the future. Both are good products I believe personally I've used duralac more and it works great. If you both prime your parts and apply duralac or mastenox you won't get any issues with corrosion. I also believe that some companies use PR which is a 2 pac polymor I think which has the added bonus of basically glueing your parts together as well. Use it all the time not sure of it's effectiveness with disimilar metals though. Let me know if you want to know any more details on the products.

Regards Jake.

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Permalink Reply by Einar Arne Kleiven on April 12, 2010 at 7:17am

Thanks, will check the internet for those products.
Here are pictures of my tailproblem:

Picture 1: aft bracket is sliding aft and into a good and nice fit. No force has been aplied to get it in this position. But with force, i belive i can get the stab 3 mm more aft, but then the fuselagebrackets are "bending"outwards, and then sqweesed back inn when mounting bolts...

Picture 2: the fuselagebracket are almost fitting nicely on the OUTSIDE of the stab-bracket...? Maybe this is a idea, making a new bracket on the outside, and making it solid...And not my first idea bending a sloppy Z bracket for mounting on the inside..

Picture 3: One must say: this is dangerous practice: using scribes (making crack starters) on the aluminumparts for the 701 !!! (delivered like this in my box)
Isnt that the first thing a aircraft-sheetworker get told to throw to someplace the pepper is growing?

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Permalink Reply by Scott Ehni on April 12, 2010 at 8:17am

You can shim the bracket out or put a joggle in it like we did.
Scott

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Permalink Reply by Einar Arne Kleiven on April 13, 2010 at 4:08am

I am maybe going away from the stainleysteel bracket. And shiming the stab. forward or aft.

When shiming the stab forward (resulting the front stab-brackets on the INNSIDE of the fuselagebrackets) i need to shim 0,8mm between the brackets when bolting.

When shiming stab backwards (to get the forward brackets on the OUTSIDE)i need to shim the aft brackets 2,3mm each out from the longerons, resulting a big gap between skin and brackets.

Picture 1: The front brackets on the inside.
Picture 2: The front bracket on the Outside (acording to drw.) Resulting in a huge load of shiming on the aft brackets.....
Picture 3 Resulting shiming when getting the front on the outside.

Anybody having a clue why this is happening? (my stab. measurements are pretty damn close, and on the fuselage it is bulkheads, skin and longerons..... Drawings must bee wrong.

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Permalink Reply by Bill Barry on April 22, 2010 at 9:36am

My drawings show the front brackets on the inside.
Bill

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Permalink Reply by Einar Arne Kleiven on April 22, 2010 at 11:48am

Which bracket are the drawing saying on the outside?

My drw. say the horisontaltailbrackets (stab.brackets) on the outside of the fuselagebrackets. And that is understandebl, because the bracket on the stab. are made of a angle extrusion, and that angle are pointing away from the fuselage!

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Permalink Reply by Bill Barry on April 23, 2010 at 8:24am

Picture #1 above is not correct.
I put a shim between the skin and the bracket (where your thumb is in #2)
The stabilizer should be able to come forward in #2 about 10 mm. This would let you use less shims in the rear (picture # 3)
Look here for pictures.
http://www.zenithair.com/stolch701/build/stab1.html
Bill