Eagler's Nest

Airframes => Single Seaters => XL => Topic started by: scottiniowa on November 13, 2015, 12:13:20 PM

Title: Tail feather Gussets
Post by: scottiniowa on November 13, 2015, 12:13:20 PM

Has anyone really gone over how big is big enough for the tail feather gussets, By this, I mean, say one of those that wraps around the .750 tube- should be say X deep on a rib?  2" or 4" or any other implied distance.

I fully understand the forming process, and using paper templates, but was more curious if this was just one of those areas that builder is just expected to wing it?

I will be showing Examples of the parts, but thought I would check first if there were any applied rules here that I was not aware of for the sizing of the gusset.

I do have the recommended rivet spacings and edge clearance notes.

Title: Re: Tail feather Gussets
Post by: joecnc2006 on November 13, 2015, 01:28:32 PM

I was kinda thinking the same thing, I wanted to draw them in solidworks and see the different sizes, I would like to cut them out on the cnc machine, lay the sheet down, nest the parts and hit the start button.
For the proper overlap I was going to see if i could find other control surfaces of different planes and try to determine the length. I was thinking about a 3"-4" overlap, but this will depend on the angle intersection.

Title: Re: Tail feather Gussets
Post by: Steve on November 13, 2015, 03:30:40 PM

Quote from: scottiniowa on November 13, 2015, 12:13:20 PM

Has anyone really gone over how big is big enough for the tail feather gussets, By this, I mean, say one of those that wraps around the .750 tube- should be say X deep on a rib?  2" or 4" or any other implied distance.

I fully understand the forming process, and using paper templates, but was more curious if this was just one of those areas that builder is just expected to wing it?

I will be showing Examples of the parts, but thought I would check first if there were any applied rules here that I was not aware of for the sizing of the gusset.

I do have the recommended rivet spacings and edge clearance notes.

Ways & Means of a Tube & Gusset master - Graham Lee:

(https://www.eaglersnest.com/forum/gallery/medium_3-131115172447.jpeg)

Title: Re: Tail feather Gussets
Post by: Dan_ on November 13, 2015, 04:06:46 PM

Quote from: scottiniowa on November 13, 2015, 12:13:20 PM

 but thought I would check first if there were any applied rules here that I was not aware of for the sizing of the gusset.

Here is a study on it...  http://arcstructural.com/images/gussetstress.pdf (http://arcstructural.com/images/gussetstress.pdf)

They seem to be saying that any gusset material outside of the 30 degree line is just adding weight.  (figure 4)

Title: Re: Tail feather Gussets
Post by: scottiniowa on November 13, 2015, 06:29:17 PM

Thanks Dan. 
Now that is the kind of thing that I'm talking about.
While it may seem complicated, it will determine a "reason and what for" to the  size/design of these gussets based on something.

I suspect that a simple formula will be deduced from this.  Such as,  
Tube dia. x 4 equals max length past a change of direction as well as distance beyond this change.  Something simple anyway.

I will do a study and then report for final review.

thanks again.

Title: Re: Tail feather Gussets
Post by: scottiniowa on November 17, 2015, 07:25:46 AM

Quote from: scottiniowa on November 13, 2015, 06:29:17 PM

I will do a study and then report for final review.

thanks again.

Ok, study done and to me it is interesting in the fact that the answers really don't seem to out there. For these reasons it seems to be a owner design preference.

• in view three different folks tail feather gussets, three different interpolation's of the plans were used.  i.e.  all three were different
• .020 was in common use
• While the rivet call out spacings on the .net and books are all about the same, many builders ignore these rules and tend to space rivets further apart than the max recommended.
• I saw no cases where builders spaced to close to edge, but several cases where they were spaced well past recommended distance (basically adding weight with no strength gain)
• I never did find any recommended length of gusset as per dia. or thickness of sub structure,  (i.e.- 3X's thickness for corner gusset or anything like that) Though there are many references to bridge gussets, but the math would not allow to go all the way down to .020 thickness, if applied-- you would have about 1" x 1" corner gussets. I didn't see anyone go that small.
• I searched in vain on my plans and two others, for any kind of dimension, only to find out they are on some plans but not all plans.
• Several applied the warm fuzzy logic of-  If it looks and feels good, it must be good.  I was hoping for more. 
• This area of the aircraft seems to be built with the line above fully in mind as it is lightly covered for the XL and many other birds of similar build.

Conclusion:

• I will design the shape to what I feel is the best shape/size for the job
• I will do the Dawn Patrol way of fastening, which is certainly fast and effective
• I will use 3M 2216 as a epoxy bond, this will allow for minimal rivets but make the tail surfaces "throw away" as there would never be a removal way if dinged. This basically uses the time vs value approach, as I could rebuild brand new fast than repair of just about any surface. Labor vs material cost,  Material cost will win with the lowest score.
• I will design around the Engleman hinge method, again, time vs money thing-vs-what really works well.
• Key here is a little bit of time making patterns will be well made later on during build with NO rethinking later.
• I will try to post these results under the down load section in a few weeks. Under "Tail Gussets" or similar. 

AS always, only then will some come out and tell me "what is wrong", no problem, I will always consider the arguments for and against a design. Of course I will always wonder why the arguments for the "how to" did not come right away.. But that is human nature.  Everyone has a theory, most don't apply theory until after they think they see a problem. But I like theory, with one of the best and most scientific being that the rings of Saturn are almost entirely composed of lost Airline luggage.. its got to go somewhere I think.

Title: Re: Tail feather Gussets
Post by: joecnc2006 on November 17, 2015, 11:30:18 AM

Scott,
Looking forward to what you come up with.

Title: Re: Tail feather Gussets
Post by: Dan_ on November 17, 2015, 12:31:00 PM

Standard operating procedure apparently is make the gusset larger that the required number of rivets by an amount slightly bigger than the edge allowance.  (twice rivet hole diameter)  

Required number of rivets should be discernible from the plans, usually never less than 3.  

Rivet spacing (pitch) (gauge) is a min of 3 times rivet diameter, and a max of 12 times.

Draw a circle around the rivet holes at the corners of your gusset the size of the edge distance allowance, and simply connect these with a tangent line drawn from each circle.   

No formulas.  

Trim and you have your gusset.  Here's your reference material...


http://www.eaa65.org/downloads/Ch01%20Standard%20Methods%20and%20Practises.pdf (http://www.eaa65.org/downloads/Ch01%20Standard%20Methods%20and%20Practises.pdf)

Title: Re: Tail feather Gussets
Post by: scottiniowa on November 17, 2015, 03:47:03 PM

Quote from: Dan_ on November 17, 2015, 12:31:00 PM

Standard operating procedure apparently is make the gusset larger that the required number of rivets by an amount slightly bigger than the edge allowance.  (twice rivet hole diameter)  

Required number of rivets should be discernible from the plans, usually never less than 3.  

Rivet spacing (pitch) (gauge) is a min of 3 times rivet diameter, and a max of 12 times.

Draw a circle around the rivet holes at the corners of your gusset the size of the edge distance allowance, and simply connect these with a tangent line drawn from each circle.  

No formulas.  

Trim and you have your gusset.  Here's your reference material...


http://www.eaa65.org/downloads/Ch01%20Standard%20Methods%20and%20Practises.pdf (http://www.eaa65.org/downloads/Ch01%20Standard%20Methods%20and%20Practises.pdf)

Thanks Dan!  Certainly makes me smile that once I say HOW I am going to proceed, that a simple and concise STANDARD comes forth.   In a sense this is a formula or if one wishes, a method to calculate the size.  AT LEAST it is something to go by. So many thanks.

Interesting, on the statement "at least 3, and discernible from the plans. The very reason I started this, as this very number question was brought up, and has gone un-answered for a long time. That simply being-- does a run comprise of 1, 2 or 3 rivets?.  And if you want to bring the plans into this... hummm,  I have a plan view of a less than 90 degree corner with 4 total rivets (2 each way) another corner with a brace, that has runs of (3 one way, 2 @90 degrees and only 1 on a brace) still another with two braces (2 rivets on the long side, 2 on a brace and 2 on another brace)  So as you can see, there is NO rhyme or reason to the plans drawings that I have. And I  certainly have found that NOT all XL plans are alike.   Thus the very core of my looking into this. 

I will be the first to tell all that my way may not be correct, but at least it will be consistently wrong.  ;-)  But now, it will be consistent to what Dan provided and that is far better than anything else that has come forth.  WE all know it works by many ways. So very true for low and slow aircraft.   Stay tuned.

Title: Re: Tail feather Gussets
Post by: Dan_ on November 17, 2015, 05:54:30 PM

Quote from: scottiniowa on November 17, 2015, 03:47:03 PM

 Interesting, on the statement "at least 3, and discernible from the plans. 

I guess the only hard and fast rule is, there are no hard and fast rules...

Title: Re: Tail feather Gussets
Post by: Dan_ on November 18, 2015, 05:47:00 AM

Scott,
A thought occurred to me about gussets wrapping around a tube.  I'm thinking of the rudder area.  

From the reading material we have found on it recently, it seems to me a good way to go about it is to make both ends of the gusset the width determined by the edge allowance.  Length of this area decided by desired number of holes and rivet pitch.  Then let the width of tube wrap part be determined by a tangent line drawn from the end hole edge allowance circle at 30 degrees or slightly more.  

I would be interested if drawing one out like this looks to be sized correctly to you.  I'm sure I am not alone on this.

Title: Re: Tail feather Gussets
Post by: scottiniowa on November 18, 2015, 07:18:37 AM

Quote from: Dan_ on November 18, 2015, 05:47:00 AM

Scott,
A thought occurred to me about gussets wrapping around a tube.  I'm thinking of the rudder area.  

From the reading material we have found on it recently, it seems to me a good way to go about it is to make both ends of the gusset the width determined by the edge allowance.  Length of this area decided by desired number of holes and rivet pitch.  Then let the width of tube wrap part be determined by a tangent line drawn from the end hole edge allowance circle at 30 degrees or slightly more.  

I would be interested if drawing one out like this looks to be sized correctly to you.  I'm sure I am not alone on this.

Dan, that could easily work, but I will try to share what the "Murphy Guide"  showed and found this to be a easy-peasy, though slightly time consuming method.

  It eliminates the 30 degree calculations and gives good shape quickly, though one part at a time. Going to try to post a few photos of prelim work, Now that I have a guide, I think this will work  consistently.

 A second note, if folks feel it should be one rivet larger, (over all size)  it would simple by adding that distance (1") to the outside shape (not the bend area)   All good.

Please note, this is intended to be a guide, unless you machines to precisely bend the center wrap bend on the center line- (I have such machine and it is still hard) This will be a shape than anyone can cut out, do the bend as close as they can to the center line. Do a quick check fit, then mark drill holes, and probably do the Dawn Patrol Method of drill and popping, no clecos. Again time vs wasting time.

Title: Re: Tail feather Gussets
Post by: liteflyt on November 18, 2015, 03:38:28 PM

Scott, just eye balling your ((https://www.eaglersnest.com/forum/Themes/default/images/icons/clip.gif) H stab A-5.jpg (http://www.eaglersnest.com/forum/index.php?action=dlattach;topic=1046.0;attach=1661) (23.63 kB, 1024x532 .)), it appears your rivet nearest
the end of the tube(s) is placed too close to the end of the tube....or do  I need glasses?

Title: Re: Tail feather Gussets
Post by: scottiniowa on November 18, 2015, 04:32:54 PM

Quote from: liteflyt on November 18, 2015, 03:38:28 PM

Scott, just eye balling your ((https://www.eaglersnest.com/forum/Themes/default/images/icons/clip.gif) H stab A-5.jpg (http://www.eaglersnest.com/forum/index.php?action=dlattach;topic=1046.0;attach=1661) (23.63 kB, 1024x532 .)), it appears your rivet nearest
the end of the tube(s) is placed too close to the end of the tube....or do  I need glasses?

Thanks for observing the photo.
Please view this jpeg, while it looks busy, this shows the edge clearances are NO less that 2 x's D of 1/8" rivet. Both on the ribs and tube. While I don't like this bottom tube start location, it is well beyond .25" from the edge..

Title: Re: Tail feather Gussets
Post by: joecnc2006 on November 19, 2015, 05:47:43 AM

Are you coping the aluminum at these areas? I would think this would weaken the ends of the aluminum sine they are not welded and the placement of the rivets at the ends would not help, would it be better to move them outward away from any coping. I'm just wondering since we are discussing this here.

Title: Re: Tail feather Gussets
Post by: scottiniowa on November 19, 2015, 08:31:17 AM

Quote from: joecnc2006 on November 19, 2015, 05:47:43 AM

Are you coping the aluminum at these areas? I would think this would weaken the ends of the aluminum sine they are not welded and the placement of the rivets at the ends would not help, would it be better to move them outward away from any coping. I'm just wondering since we are discussing this here.

a good point Joe.  Not often I would defer a question, but this one I will.  as you estimated, I have coped the ends. And this may/may not make your argument true. As inside with NO coped ends, would not have any leading or trailing edge support vs coped. That being said, your statement is also true.

To date, NO one (designer or builders)  has said, yeah or nah on this.  NON- Coped certainly would be easier...to make and draw.

Completely open on this.- depending on what is suggested with facts/theory this will slightly alter the look of the gusset by 1/2 the D of the tube. (larger) 
Scott

Title: Re: Tail feather Gussets
Post by: joecnc2006 on November 19, 2015, 09:29:16 AM

I would vote for non coping the aluminum since we are using the gussets. easier build and a little less weight on the aluminum tubs although the larger gussets may negate this. 
There are two reason I look at it this way.
1. The fuselage is coped but they are welded no gussets.
2. The wing ribs are built with no coping but uses gussets to compensate the void area.

Title: Re: Tail feather Gussets
Post by: liteflyt on November 19, 2015, 12:38:28 PM

Scott, your A-5 drawing shows the tube ENDS protruding Into the joining tube...probably not a good idea....
suggest you redraw showing what you really mean.   Got my "cheaters" on now.....  ;^)

Title: Re: Tail feather Gussets
Post by: joecnc2006 on November 19, 2015, 12:47:22 PM

Quote from: liteflyt on November 19, 2015, 12:38:28 PM

Scott, your A-5 drawing shows the tube ENDS protruding Into the joining tube...probably not a good idea....
suggest you redraw showing what you really mean.   Got my "cheaters" on now.....  ;^)

As he mentioned before the tubes do not protrude into the adjacent tubes they are intended to be coped around them.

Title: Re: Tail feather Gussets
Post by: scottiniowa on November 19, 2015, 12:51:42 PM

Though it may appear through the use of Jpegs that a part extends into another, I can assure I don't have this done.  Most likely if I have ghosted a part to better show a internal view, it can often appear that the lower side of a coping is poking into  the exterior frame.  This is really true if you were looking at coped frames.

But, with recent talk, about doing the extra work for coped ribs and using gussets, the need for coping is probably nil. 

When I can get back to by guide, I will take the coping out of all alum ribs, re-space rivet edge clearance, which in turn will cause a reshaping of the actual gusset.  Certainly the case where one change makes 10 more.  I will stick with my three rivet rule, and if someone wants to make it smaller, it is simply a matter of reducing size by one out rivet per intended area of reduction.

thanks for checking things out.

Title: Re: Tail feather Gussets
Post by: scottiniowa on November 19, 2015, 12:59:56 PM

Quote from: joecnc2006 on November 19, 2015, 12:47:22 PM

As he mentioned before the tubes do not protrude into the adjacent tubes they are intended to be coped around them.

Tube to the right  of my  jpeg photo, is in fact a tube  See your drawing sheet #1 upper left
The other two items, which appear to be tubes are in fact coped ribs and do not protrude into the main tube.
I could have and should have supplied more photos to show this better, but thought 4 top views were enough to get started.

As stated just a note or two ago, I can and will reduce this same ribs and even at that, if the jpeg was viewed looking aft, would still appear they were protruding
Had I made this jpeg with hidden lines show, it would have been very busy, but dashed lines.  Or with lines hidden, would appear they were hiding inside of the tube.

Only way to win on that would be to show top-side and front views.

cheers

Title: Re: Tail feather Gussets
Post by: joecnc2006 on December 25, 2015, 08:44:54 PM

Any further words on this.

Title: Re: Tail feather Gussets
Post by: scottiniowa on December 26, 2015, 12:28:04 PM

Quote from: joecnc2006 on December 25, 2015, 08:44:54 PM

Any further words on this.

Hi Joe,
   I certainly did learn that there was a difference of opinion out there, but most of the time those differences are expressed only after a part is said to be made a certain way. LOL  Nothing wrong with that, but it sure seems to be the case.
    I got hired on a another project, so got pulled away (for pay) but soon to be back to this.

As per the first line- I am almost certain, no matter what shape/pattern I show, someone will certainly say it is not correct, and that is ok too. As they will be strictly offered as ONE possible shape/form for these gussets. If I error, it will be towards the safe side. So with that in mind, I will have NO runs of rivets of 2 only.   I will always have 3 or more.  Edge distance has been established  (2 x dia. of hole size)  as well as min/max spacing. I will use .750" spacing.

cheers
Scott

Title: Re: Tail feather Gussets
Post by: Aerodude45 on January 23, 2016, 09:43:08 PM

I like the idea of using number of rivets and edge distance between rivets as a way to determine rivet size. I'd like to propose an experiment, which I have the means and materials to try. Please let me know if you think this is worthwhile or would like to see a different methodology.

My hypothesis is that 6D rivet-spacing with 2D edge distance with each run having 3 rivets and with the tubes coped is the lightest option that will result in adequate strength. My assumption for adequate strength will be tube failure before gusset failure when the tubes are loaded in bending with the load force applied perpendicular to the tube and parallel to the plane of the gusset. (I welcome any arguments against this assumption; I don't know if that determines what is adequately strong. I also seem to recall my professor in A&P school last year saying failure in shear just before failure in bearing is preferred, but have not found anything online to corroborate this.) This force will be applied so that the gusset is loaded in tension (obviously in compression a .020" gusset will buckle). I will use the same 90 degree test joint configuration for all test pieces, and will test the configuration that is most successful in a 3/4"OD .035"wt to 3/4" .035"wt joint on the other joint-dimension configurations found in the plans (.020" C-channel to 3/4", .020" C-channel to 3/8", 3/8" to 3/4"). My joint configuration is detailed in the attached drawing.
 
(X4) 3/4" to 3/4" .035 joints (1 pair coped vs uncoped, 1 set 3D and 6D rivet spacing)
(X1) 3/4" to 3/8", most successful configuration from above
(X1) 3/4" to .020" Channel, same config
(X1) 3/8" to .020" Channel, same config

I have some spare aluminum tubing and .020" gusset material. I was going to make my gussets by drawing the tail in AutoCAD, using rivet spacing and number of rivets to determine gusset dimensions, drawing a circle with a radius of 2D around the last rivet, then drawing lines tangent to those circles much like what was mentioned above. I was also planning on coping. Hopefully this experiment would allow an "official" conclusion to be reached.

Title: Re: Tail feather Gussets
Post by: s johnson on January 24, 2016, 07:01:39 AM

Jakob,

Seems to me the FAA has already done extensive testing and pretty much states what should be used as far as spacing requirements in AC43-13 . You must be bored. Hurry up and get your bird rebuilt so we can go flying together this spring/summer  :-)

Scott J.

Title: Re: Tail feather Gussets
Post by: scottiniowa on January 29, 2016, 06:34:23 PM

Quote from: Aerodude45 on January 23, 2016, 09:43:08 PM

I like the idea of using number of rivets and edge distance between rivets as a way to determine rivet size. I'd like to propose an experiment, which I have the means and materials to try. Please let me know if you think this is worthwhile or would like to see a different methodology.

 

Aerodude45,  Though it may be true, I have not seen using the number of rivets and edge distance calculation to determine rivet size.  I would have a hard time to find any where on this aircraft that 1/8th stainless rivet won't do the trick. And yes, 2D for edge clearance,  and as many books show, the spacing can very a fair bit, but using min and max, will determine much.

You had a fair bit of formula stuff, but I couldn't determine to what/which it was going to be used.  It looks like you want to do testing, I'm sure the group would be interested in your findings.  I am pretty sure in the time to do "proper" testing, the entire tail structure could be built and well on your way to having aircraft done. 

cheers
Scott

Title: Re: Tail feather Gussets
Post by: Aerodude45 on January 29, 2016, 06:53:38 PM

Scott, that was a typo. I meant "gusset size", not "rivet size". Sorry about that.

Title: Re: Tail feather Gussets
Post by: joecnc2006 on February 27, 2016, 06:53:48 PM

Here is some text on rivets.

EDGE DISTANCE.— 2x rivet diameter but not > 4x rivet diameter. The edge distance for all rivets, except those with a flush head, should not be less than twice the diameter of the rivet shank nor more than four times the diameter of the rivet shank. Flush-head  rivets  require  an  edge  distance  of  at  least 2 1/2 times the diameter. If rivets are placed to close to the edge of the sheet, the sheet is apt to crack or pull away from the rivets. If they are placed too far away from the edge, the sheet is apt to turn up at the edge.
RIVET PITCH (SPACING) — (4 to 6 times rivet diameter) 1/8 rivet = ½ to ¾ inches.
  Rivet    spacing    (pitch) depends  upon  several  factors,  principally  the thickness of the sheet, the diameter of the rivets, and the  manner  in  which  the  sheet  will  be  stressed.  Rivet spacing should never be less than three times the rivet diameter. Spacing is seldom less than four times the diameter nor more than eight times the diameter
 
TRANSVERSE PITCH.—  (75 percent of existing rivet pitch ) 1/8 rivet = 9/16 inch.
 When  two  or  more rows  of  rivets  are  used  in  a  repair  job,  the  rivets should  be  staggered  to  obtain  maximum  strength. The  distance  between  the  rows  of  rivets  is  called “transverse   pitch.” Transverse  pitch  is  normally 75 percent of existing rivet pitch, but should never be less than 2 1/2 times the diameter.