Tail Hinges

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tonyp51
Posts: 4
Joined: Sun Mar 05, 2017 8:36 pm
Location: Mojave CA

Tail Hinges

Post by tonyp51 »

Do I need to recess my tail hinges? What is the advantage to recessing them? My Hinges are from Oscar.
thx!
Tony
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taildrags
Posts: 637
Joined: Tue Mar 07, 2017 10:39 pm

Re: Tail Hinges

Post by taildrags »

Tony; the biggest advantage to recessing the hinge bases is that it reduces the gap between the surfaces, which is said to improve control effectiveness by reducing the tendency of higher-pressure air on one side of the surface to bypass through the gap and reduce the airflow over the control surface. Out on the wings, using piano hinges along the full length of the ailerons does even better than that by sealing the gap entirely, and I suppose we could also use piano hinges on the tail surfaces to close those gaps too.

I have a set of the cast hinges here in front of me. Measuring between the bottom of the hinge bases (what the gap width would be if you did not recess the bases into the control surface spars), it's about 7/8". Measuring between the tops of the hinge bases, the gap reduces to about 1/2", or about a 40% reduction in gap width. I have not flown with the wider gaps myself, but have heard that reducing or closing the control surface gaps improves effectiveness and response.

Undoubtedly, one advantage of *not* recessing the hinge bases is that you have more room to insert the hinge pins and cotter pins in that wider hinge gap. I have found that it is a very tedious and frustrating process to get all of those pins done and the tails of the cotter pins wrapped and clipped. Definitely easier with two people, definitely easier if you have smaller fingers.
tonyp51
Posts: 4
Joined: Sun Mar 05, 2017 8:36 pm
Location: Mojave CA

Re: Tail Hinges

Post by tonyp51 »

Thanks for the quick reply. I will recess my hinges.

Tony
User avatar
taildrags
Posts: 637
Joined: Tue Mar 07, 2017 10:39 pm

Re: Tail Hinges

Post by taildrags »

Another update on the Vi Kapler-style cast aluminum hinges. The foundry that I work with has just run a new batch of castings for me, somewhere in the neighborhood of 260 sets, but I have not seen them yet and have no idea what the rejection rate is going to be. Even with the anticipated rejection rate, I should be able to get another 25 sets of hinges out of this batch, which should supply builders well past the next presidential election <ha, ha, ha... ;o)> I currently have enough castings in inventory to fulfill all standing orders. Now to find the time to get them done for all of you...
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