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Offset flap hinge position

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Old 09-04-2010, 06:41 PM
  #1
hcuellart
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Default Offset flap hinge position

Hello guys,
I have never installed offset flap hinges before and I am a bit lost[&:]
Does anybody have any close up pics that can help me determine how far into the flap (offset) these get installed. I have searched half a day and have not come up with anything...
Thanks!
Homero
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Old 09-04-2010, 08:55 PM
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Default RE: Offset flap hinge position

Homero,

You may need to explain a little more about what you are asking. "Offset hinges", like the one in the first picture below are typically used for doors and not flaps. You may be asking how to offset the center of the flap pivot point. If so, you can imbed Robart type hinges, sort of like in the second photo. Or, you can use a standoff flap pivot point, such as in the third photo. There are other methods as well.

It might help if you mention the jet you are building.

Craig
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Old 09-04-2010, 11:12 PM
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Default RE: Offset flap hinge position

Sorry for not being specific. The hinges are Tamjets offset flap hinges like the ones in the pics. I am building a YA Starfire EDF.
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Old 09-05-2010, 05:57 AM
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Default RE: Offset flap hinge position

Excellent Starfire build thread can be found at http://www.rcgroups.com/forums/attac...mentid=2238867
However, it shows the flaps hinged using Robart hinge points. Don't know if the offset hinges are something new that YA has added or something you are choosing to implement, but most typically you want the pivot point of the hinge to be close or on the same axis as the hinge line.

This photo should give you an idea of the hinge location.

{akamaiimageforum}/upfiles/56138/Ga78386.jpg
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Old 09-05-2010, 06:59 AM
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Default RE: Offset flap hinge position

Quote:
ORIGINAL: hcuellart

Sorry for not being specific. The hinges are Tamjets offset flap hinges like the ones in the pics. I am building a YA Starfire EDF.
I've never seen or used that type of hinge but it looks to me that you would position the flaps in the "up" position and temporarily hold them in place, such as with tape. Cut slots on the bottom near the wing trailing edge and flap leading edge corresponding to the location of the hinge tabs, with the pivot point centered above the trailing edge of the wing. There should be material (usually hard balsa) in the wing and flaps where each hinge attaches and one of the hinges should line up with the flap servo arm (make sure the "control horn" is on the flap side). You can cut off the upper "control horn" portion of the other hinges. Leave a little extra open area around each hinge opening, fill it with Aeropoxy or similar, and slide them in place, making sure they are perpendicular to the wing/flap and in line with each other.

Because the hinge pivot point is "offset" below the flap centerline, it creates a down and aft movement of the flap versus just down. This more or less emulates a Fowler flap and theoretically increases the wing area, making the flaps more effective.

Actually, those hinges look pretty clever and should be fairly easy to install. Hope this explanation makes sense.

Craig
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Old 09-05-2010, 07:08 AM
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Default RE: Offset flap hinge position

Just make sure that the hinge points line up perfectly or else they will work against each other as the flap deploys. Also, you will need a very high torque servo since this setup does not have allot of mechanical advantage. In fact, there is allot of mechanical "disadvantage" with this setup.

Jim
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Old 09-05-2010, 07:54 AM
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Default RE: Offset flap hinge position

These are the same type hinges used on the Jet Legend L 39 flaps. They work great but are designed just for flaps .If you look at some of JL L 39 build threads you can see how they are installed.
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Old 09-05-2010, 08:00 AM
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Default RE: Offset flap hinge position

These are the YA flap hinges installed on a Facet 2300
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Old 09-05-2010, 11:48 AM
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Default RE: Offset flap hinge position

OK, thanks guys for all the input!! I worked yesterday night into putting some balsa blocks like Craig suggests into the wing. My biggest concern was if I needed to get the pivot point in the hinge line or a bit backwards. In fact in the manual they suggest for the aileron hinge point (Robart type) to be recessed 1/4" into the leading edge of the aileron, should I use this as a reference line and get the same for the flaps? I will look at those links you all provided. Again thanks!!

Those Yellow flaps hinges look better than mine... I like the fact you won't get exposed linkages!!
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