wing tip shape

[Lance Van Nostrand]

John,
Yes, this clears it up directly.  I've done this before on IMAC planes using 
robart pin hinges and never connected the dots for this discussion.  Pattern 
plane tapered wings are thicker at the root end so the pivot point is deeper 
in the control surface than at the tip.  I've never tried this with flat 
style hinges, fearing they would bend.  They are also not very deep.  it is 
interesting that you've made this work for you.
--Lance

----- Original Message ----- 
From: "John Pavlick" <jpavlick at idseng.com>
To: <discussion at nsrca.org>
Sent: Thursday, November 25, 2004 2:00 AM
Subject: RE: wing tip shape


> Lance,
> Sorry for the confusion. I should have mentioned that I don't normally use
> CA hinges. Especially in foam wings, unless the caps in the control 
> surface
> area are as thick as the hinge depth. I prefer pin hinges, and I pin them 
> in
> place too (dowels or toothpicks). The problem with binding is aggravated 
> by
> the fact that the CA hinge pivot point is exactly between the two parts,
> because that's where it is allowed to flex (the hinge is not supported by
> the surfaces). With a pin hinge, you can move the pivot point to reduce 
> the
> interference. The way I was taught to understand this was to think of the
> geometry involved. The pivot point should be at the CENTER of the radius,
> not on the edge. If you sink the hinge into the control surface you can
> realize this with very little gap at all. The control surface now rolls on
> the radius instead of binding because the pivot point is always the same
> distance from the edge. To put this another way, imagine if a wheel had 
> the
> axle located on the edge of the rim instead of in the center. How far 
> would
> it turn? Unfortunately, in order to do this on a thick surface you would
> need to sink the hinge pretty deep (1/2 the thickness of the surface). The
> area near the hinge (in the movable surface) needs to be relieved to
> accomodate the hinge on the opposite surface too, because it is in the 
> arc.
> If you consider the fact that on pattern planes we don't need to move the
> surfaces to extreme angles (like 3D planes do) you can make some tradeoffs
> and still get acceptable results. Hope this helps.
>
> John Pavlick
> http://www.idseng.com
>
>
>
>
>> -----Original Message-----
>> From: discussion-request at nsrca.org
>> [mailto:discussion-request at nsrca.org]On Behalf Of Lance Van Nostrand
>> Sent: Thursday, November 25, 2004 12:47 AM
>> To: discussion at nsrca.org
>> Subject: Re: wing tip shape
>>
>>
>> Please someone explain this rounded control surface thing to me.
>> If we use
>> a CA hinge and but the aileron to the wing, then the only way the surface
>> can move is if it has a beveled point.  A rounded interface will
>> bind unless
>> the aileron has a gap to begin with.  However, if all we are saying is to
>> round the part of the bevel that blends into the aileron, then I get it.
>>
>> Confused again....
>> --Lance
>>
>
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