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Shoestring

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geraldmorrissey

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Aug 11, 2008
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42
I've been building a bone stock Shoestring for a long time. The elevator to horizontal stab hinge fittings are a concern. Threaded rod with a 90 degree bend at the horizontal stab, a clevis bolt on the elevator. No provisions to restrict rotation of any of the details. All wood structure. Want to keep the wood structure but need some ideas on some options on the hinge details. The stock arraignment seemed to work fine under racing conditions but the origional was a racer, not meant to last. it's the only part of the airframe that gives me pause. Back in the early 80's Ray Cote also expressed concerns to me about this design. At the time he was flying "Judy" but it had a AL horizontal stab, elevators and a different hinge arrangement. It also had a 3" fuselage stretch fwd of the wing and a 3" stretch aft of rhe wing. May consider that but needs much further consideration. Any comments on the empennage hinges appreciated. This will be a sport aircraft not a racer. I can provide much more detail per the prints.
Thanks
Gerry
 

Mohawk750

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Jan 1, 2021
Messages
111
Location
Ottawa, Ontario
I'm not sure what you are dealig with for space available bu i just happened to be looking at the Janowski J1-B plans tonight and coppied the aileron detail as an idea. The elevator and rudder use the same hinge arrangement fabricated from pieces if aluminum angle. I think it's .090 or .125 flanges and .250 pins. You would have to size to fit your situation but you get the idea. You could also bend smaller angles out of 4130 steel.

J1-B Aileron hinge.JPG

Another option would be the ANSeries eye bolts in pairs but they are expensive and require a nut on the blind side.an44drilledb.jpg
 

Tiger Tim

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Apr 26, 2013
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Thunder Bay
Seems to me that Tantrum1 is worth talking to as IIRC the Snoshoo design is an evolved Shoestring.

 

Victor Bravo

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Jul 30, 2014
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KWHP, Los Angeles CA, USA
A sport airplane will likely fly much more hours/miles than a racer, so I think in this case you need a more airworthy hinge, crack resistant over a much longer period of time, than you would need for a racing airplane.

If you can get a really good psychic to have a seance and ask Rod Kreimendahl personally... he may be able to tell you how much load and cycle time he put into that design.

Absent that, IMHO go the conservative route and build in more lifespan and duty cycle than a piece of threaded rod that has a bend in it.
 

Skyroller

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Jan 21, 2021
Messages
5
The hinges on my shoestring are built per plans just like this. It is the original Yellow Jacket shoestring and has a lot of time on it with no issues. I can sat that both the clevis bolt and the hinge pins have been installed wet with epoxy when screwed to the respective spars.
 

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rv7charlie

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Nov 17, 2014
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Jackson
The OP's description of 'threaded rod, bent' doesn't seem to be anything at all similar to that pdf. The pdf looks like a bolt (likely an AN bolt) that was heated, bent, then had the head removed, and was then reinforced on both sides of the bend with welded angle. Are the description and the pdf from different sets of plans?
 

Skyroller

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Jan 21, 2021
Messages
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The OP's description of 'threaded rod, bent' doesn't seem to be anything at all similar to that pdf. The pdf looks like a bolt (likely an AN bolt) that was heated, bent, then had the head removed, and was then reinforced on both sides of the bend with welded angle. Are the description and the pdf from different sets of plans?
The PDF plans are the original Shoestring drawings made by Landis Ketner sorry bad spelling. My airplane was the 2nd shoestring ever built and the first ever off of the existing plans.
 

TFF

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Apr 28, 2010
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Memphis, TN
Looks like it’s designed to remove easy for transport. Double safety? Nut on the threaded part, bolt or screw through the flange.
 

wsimpso1

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Oct 18, 2003
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Saline Michigan
I would be inclined to inquire into service histories of the fleet. If there are airplane count and hours are tiny and/or folks have problems, consider modeling the thing up and analyzing it. Opposite case is there might be a bunch of these with hundreds of hours and no issues. I caution against simply eyeballing it, and think it wise to govern your actions by an honest evaluation of the existing experience.

Billski
 

Skyroller

Member
Joined
Jan 21, 2021
Messages
5
I would be inclined to inquire into service histories of the fleet. If there are airplane count and hours are tiny and/or folks have problems, consider modeling the thing up and analyzing it. Opposite case is there might be a bunch of these with hundreds of hours and no issues. I caution against simply eyeballing it, and think it wise to govern your actions by an honest evaluation of the existing experience.

Billski
The hinge method listed on the print has been Formula 1 standard since the 70s with no known failures that I know of and I know quite a few still being built this way. I can say if some one is worried about the eye bolt rotating this problem can be fixed by welding a small bushing to the non bearing side about 1/4 inch long this will allow more positive pin engagement.

Eric Dienst
Race 85 Deja Vu
 

geraldmorrissey

Active Member
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Aug 11, 2008
Messages
42
My "threaded rod" description was inaccurate and misleading. Inexcusable when describing control system components. It is encouraging that this hinge system has a service history beyond the origional airplane and is still being fabricated today. Yellow Jacket was the reason I bought the drawings back in the late 70's. I still have that magazine with the beautiful yellow and black airplane on the cover. Thanks to those who responded.
 

geraldmorrissey

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Aug 11, 2008
Messages
42
Is the wing stock, is your fuselage per the print dimentions? If so what is your height? What a transformation!
Thanks
 

proppastie

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Feb 19, 2012
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NJ
Do you have any photo's of the hinges?

Thanks
sorry no....... just a general statement as regards standard design practice ....I will see f I can find examples and post them......what do the other builders of this design do?
 

proppastie

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Feb 19, 2012
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You will have to do a little design to add features to your hinges....a little welded tab or threaded boss for a screw....assuming you can not copy a successful design.....might start another thread on "Control Surface Stop"....I am sure others here have examples they can post pictures of.
1612017382663.png 1612017446685.png 1612017664580.png
 
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