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Author Topic: Leadout Clearance  (Read 218 times)

Online Ken Culbertson

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Leadout Clearance
« on: March 21, 2020, 12:51:44 PM »
One of the things I have never found an acceptable solution for is clearance for the leadouts with adjustable settings.  Most designs I look at simply do not have clearance for the wide range of settings available in the average leadout guide.  This leads to sawing through things and sticky, or even worse, locked controls.

When I design a wing I always plot the leadouts from full forward to full back and clear out and brace the ribs to match.  With a decent bracing pattern and tight cap strips, a balsa wing will stay strong and not flex too differently than the outboard, but I am not clear how you achieve that in foam which I will be using next.  I plotted out the "clear" zone and it came out nearly 1/2 of the inboard wing.  I am afraid that foam will crush easily or flex with out a center spar from half span out to the tip.  I am also concerned about uneven flex which would affect the flaps.  Should I perhaps core both panels the same?

Many, even most of you have experience with foam wings.  I have used them on sailplanes but never on a PA.  I would do it in Balsa with the newer slanted rib format but I will not have the tools to make it true.  I really do want to get back in the air as soon as I get past rebuilding my house and shop so designing a wing and getting it made early is my plan.

Do you know how traumatic it is to be confined to your house and not be able to build?  All I have is pestering all of you with dumb questions and listening to my wife complain about the germs.  I am sure Psychiatrists have a neuroses it will fit into! LL~

Ken
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Online Brett Buck

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Re: Leadout Clearance
« Reply #1 on: March 21, 2020, 03:51:52 PM »
One of the things I have never found an acceptable solution for is clearance for the leadouts with adjustable settings.  Most designs I look at simply do not have clearance for the wide range of settings available in the average leadout guide.  This leads to sawing through things and sticky, or even worse, locked controls.

When I design a wing I always plot the leadouts from full forward to full back and clear out and brace the ribs to match.  With a decent bracing pattern and tight cap strips, a balsa wing will stay strong and not flex too differently than the outboard, but I am not clear how you achieve that in foam which I will be using next.  I plotted out the "clear" zone and it came out nearly 1/2 of the inboard wing.  I am afraid that foam will crush easily or flex with out a center spar from half span out to the tip.  I am also concerned about uneven flex which would affect the flaps.  Should I perhaps core both panels the same?

Many, even most of you have experience with foam wings.  I have used them on sailplanes but never on a PA.  I would do it in Balsa with the newer slanted rib format but I will not have the tools to make it true.  I really do want to get back in the air as soon as I get past rebuilding my house and shop so designing a wing and getting it made early is my plan.

Do you know how traumatic it is to be confined to your house and not be able to build?  All I have is pestering all of you with dumb questions and listening to my wife complain about the germs.  I am sure Psychiatrists have a neuroses it will fit into! LL~

Ken

    I would certainly start with both cores cored the same!  But, to get clearance, I take a length of arrowshaft, wrap it with 240 grit sandpaper, and just saw away at the interfering foam from the inboard tip in until everything fits. The foam spar does nearly nothing for strength or rigidity near the tips so removing it also doesn't do any harm. The wood cap over the wingtip will keep it from collapsing.

     Brett

Online Ken Culbertson

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Re: Leadout Clearance
« Reply #2 on: March 21, 2020, 04:02:28 PM »
Ken, it is far  more traumatic to be at sea for 9 months and being unable to build...and the magazines come in the mail only if the COD is in range of the nearest NAS or the damn tanker has the mail... y1 LL~ H^^
It was the guy on the tanker that stole your magazines.  I had 2 tours in the USAF where I couldn't build or fly.  One 13 mos the other 6.  Fortunately beer was $.10. LL~

Ken
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If it is not broke, don't fix it.
USAF 1968-1974 TAC

Online Ken Culbertson

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Re: Leadout Clearance
« Reply #3 on: March 21, 2020, 04:07:55 PM »
    I would certainly start with both cores cored the same!  But, to get clearance, I take a length of arrowshaft, wrap it with 240 grit sandpaper, and just saw away at the interfering foam from the inboard tip in until everything fits. The foam spar does nearly nothing for strength or rigidity near the tips so removing it also doesn't do any harm. The wood cap over the wingtip will keep it from collapsing.

     Brett
Thanks Brett.  I expected that there was enough strength but never having done foam, I wasn't sure.  I will do it as you suggest.  Pretty much what I did on balsa but I was able to shore it up with "X" braces to keep it from crushing after clearing the leadouts.  I have seen some really experienced fliers have to dig into a wing to find out where the binding came from.

Ken
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USAF 1968-1974 TAC

Offline Motorman

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Re: Leadout Clearance
« Reply #4 on: March 21, 2020, 06:06:23 PM »
You only need about 3/4" of travel on the slider unless you completely miss where to install it.


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Online Ken Culbertson

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Re: Leadout Clearance
« Reply #5 on: March 21, 2020, 06:16:11 PM »
You only need about 3/4" of travel on the slider unless you completely miss where to install it.


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Maybe you do but I have used as much as 2" from full fwd to full back.  Some planes are completely different animals in different weather and CG conditions.  Once it is trimmed and the standard position is established about 1/2" either way seems to do it for me but I won't know where that happy spot is for 10-20 flights.  Either way, if you haven't cleared the ribs, you are going to have problems.

Ken
AMA 15382
If it is not broke, don't fix it.
USAF 1968-1974 TAC


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