Scott ( in Iowa ) K block idea

[Dave Stroud]

I think Scott's idea of the K blocks in the wing rib idea might be a good one but I'd envision covering that length in the aft end of the aileron bay with 8mm ply instead of aluminum sheet. The reason for this is that I don't have a real good way of bending the edges of thin aluminum along the length of an aileron bay in a reliably straight manner.  But, with either al. or ply, it would be necessary for each of those 6 K blocks to be perfectly shaped and perfectly in position with each other for the cove surface to be nicely attached. One way might be to put one on at each end during rib building and fit in the rest when all other ribs are mounted on the spar. Leonard recommends a simple flat application of fabric which is dead simple but flat. What have others done....any ideas or thoughts on this idea ? Thanks..

[Darren C]

Hi Dave.

This is my take on bending the aileron bay having just done it the other day. 

http://www.mykitlog.com/users/display_log.php?user=ontherun&project=2554&category=0&log=235403&row=4

The pressure of the bent .8mm plywood held itself in place whilst the glue set.  Took no time at all.

Darren.

[Dave Stroud]

Nice one, Darren...thanks. I'm just trying to keep my brain a little ahead of the game so I don't have to rip stuff out later. Your solution looks good and your build site is excellent. Thanks for taking the time to do that.

[scottiniowa]

I think Scott's idea of the K blocks in the wing rib idea might be a good one but I'd envision covering that length in the aft end of the aileron bay with 8mm ply instead of aluminum sheet. The reason for this is that I don't have a real good way of bending the edges of thin aluminum along the length of an aileron bay in a reliably straight manner.  But, with either al. or ply, it would be necessary for each of those 6 K blocks to be perfectly shaped and perfectly in position with each other for the cove surface to be nicely attached. One way might be to put one on at each end during rib building and fit in the rest when all other ribs are mounted on the spar. Leonard recommends a simple flat application of fabric which is dead simple but flat. What have others done....any ideas or thoughts on this idea ? Thanks..

The intent was to install in "place" the K blocks, while in the rib jig, thus having each one in the exact same location..(one would think this to be true as all other parts get put into exact placement, in the jig. so not sure why these K blocks would get out of line-  These K blocks, was to allow a very close and clean fit-up for the ailerons  with the aluminum cusp being the providing factor and easy to make.  We make these kinds of shapes on a a alum. trim stock brake that any house builder would have.  So would look for that carpenter.. Only need two.

Of course there is many ways to skin the cat, and a few of them have been shown.

Sounds like your on the right track.

[Garyverrier]

Scott I am building a xl, unclear on how the hor. stab mounts to airframe?. any photos would help. Thanks Gary. garyverrier@yahoo.com or pilotgary2@gamail.com

[CHARLES DEBOER]

Scott I am building a xl, unclear on how the hor. stab mounts to airframe?. any photos would help. Thanks Gary. garyverrier@yahoo.com or pilotgary2@gamail.com

The index in the back of your drawing package references only page #1 for the stabilizer, but drawing #3, #19 and #25 will give you a better understanding of how it is attached.  Drawing #19 has the detail for connecting the right and left halves of the Stab.  These connectors bolt through the longeron. Most of the detail is on drawing #25.

[Bud K]

Dave, I went with the K block per Scott's plans.  I too had difficulty bending the aluminum on my Harbor Freight brake.  I eventually was able to borrow my general contractor's 12' brake over the Christmas holidays and bent the aluminum in a couple of hours.  When the ailerons are installed, you can't even see the creases formed by the brake.  Turned out pretty clean. 

When building my ribs, I built them complete except the areas that required the K blocks and the aileron hinge blocks.  I then sandwiched all of the ribs together and completed all of my rough sanding for shape, trailing edge alignment.  The ribs needing the K blocks and hinge blocks went back into the rib fixture to add those features. 

I found this process required a lot of planning and attention to details but the finished product turned out pretty nice. 

I was also a little concerned about the weight increase that K blocks add to the rib. I weighed 8 standard, complete ribs and 8 with the K blocks/gussets added.  Total aircraft weight added with the K block approach was 62 grams (0.14 lbs). I consider this a wash since I didn't need to add wood reinforcement between the K blocks on the aileron ribs. 

[Dave Stroud]

Thanks for that, Bud. Did you put any twist or washout in your wings ?

[Bud K]

I did not build any washout in the wing structure.  I found keeping everything lined up and straight difficult enough on a flat building surface without worrying about building in washout.  Anyway, the structure has flexibility torsionally at this stage so a few degrees of washout shouldn't be a problem.  I don't know what will happen when covering is on but my assumption is that rigging the necessary washout won't be a problem.

[scottiniowa]

Dave, I went with the K block per Scott's plans.  I too had difficulty bending the aluminum on my Harbor Freight brake.  I eventually was able to borrow my general contractor's 12' brake over the Christmas holidays and bent the aluminum in a couple of hours.  When the ailerons are installed, you can't even see the creases formed by the brake.  Turned out pretty clean.  

When building my ribs, I built them complete except the areas that required the K blocks and the aileron hinge blocks.  I then sandwiched all of the ribs together and completed all of my rough sanding for shape, trailing edge alignment.  The ribs needing the K blocks and hinge blocks went back into the rib fixture to add those features.  

I found this process required a lot of planning and attention to details but the finished product turned out pretty nice.

I was also a little concerned about the weight increase that K blocks add to the rib. I weighed 8 standard, complete ribs and 8 with the K blocks/gussets added.  Total aircraft weight added with the K block approach was 62 grams (0.14 lbs). I consider this a wash since I didn't need to add wood reinforcement between the K blocks on the aileron ribs.  

Just a few thoughts- and these are just personal observations.
 First,  Budd that looks great  (your work) 
On the bending of cove-  I will just touch on what we did in test (but then got busy back on the big birds-2000# gross craft) and that was simply putting only one bend at the top and bottom of the cove, and none in the middle. But did this on very light material (12 thou- valley sheeting from roof work) as we are only keeping the air from turbulation (dirty air causing drag)  and not using this area as a structural component.  Then with correct sized pvc tube, applied strapping to pull the cove material to the K block- I would not consider this a 1 man job, but then again, it doesn't take long and certainly can be done.  by using 3M-2216  this bonds far stronger than the actual metal.

The whole basis of the K-block area or parts is just like Budd said.   A little bit of added extra work up front produces a very clean look later. And I personally think, saves time and produces what we hoped for.

WE all know how weight adds up, but in this case, the .14 pounds gained, can easily "save" weight if you compare to the then added wood cove vs the round  alum cove.   Ying and yang perhaps...

I do like Budds comments about the -"Required planning and attention" -  I find this SO TRUE, on almost all phases of aircraft building...  It was my greatest hope to show this in action...on the prints. Some have suggested that I don't need 2-3 decimal points showing, but if many builders plan to these levels, even if off a bit, things work out nicely.   vs.  builders seeing 1.0" on  the plans but building with .890" to 1.1" and pretty soon get the tail wagging the dog in the build.

I didn't answer anything to the washout question...  Recalling the great amount of racking involved in getting the diagonal in place, should indicate what can be done.  Building this in, is very very hard...I would be the last to suggest to give this a go, as the required stiff fixtures on each are a must...and seldom on hand.

cheers all!

[Dave Stroud]

Scott in Iowa said...

"I didn't answer anything to the washout question...  Recalling the great amount of racking involved in getting the diagonal in place, should indicate what can be done.  Building this in, is very very hard...I would be the last to suggest to give this a go, as the required stiff fixtures on each are a must...and seldom on hand."

Scott, could you please elaborate on your statement above ? I'm wondering what pitfalls concern you and I'm just trying to learn here. If you build the whole wing flat, there's going to be all the diagonals, braces etc. to be built in and finally the nose D ply to lock in everything. Everything has to be squared for sure during the whole process. To build in the 2 degree washout, the rear spar at the outer end will need to be jacked up about 1 inch. All else previously mentioned will need to be adhered to anyway. What stiff fixtures do you refer to ? My intention would be to build in the washout as the wing is assembled. Thanks.

[Steve]

Scott in Iowa said...

"I didn't answer anything to the washout question...  Recalling the great amount of racking involved in getting the diagonal in place, should indicate what can be done.  Building this in, is very very hard...I would be the last to suggest to give this a go, as the required stiff fixtures on each are a must...and seldom on hand."

Scott, could you please elaborate on your statement above ? I'm wondering what pitfalls concern you and I'm just trying to learn here. If you build the whole wing flat, there's going to be all the diagonals, braces etc. to be built in and finally the nose D ply to lock in everything. Everything has to be squared for sure during the whole process. To build in the 2 degree washout, the rear spar at the outer end will need to be jacked up about 1 inch. All else previously mentioned will need to be adhered to anyway. What stiff fixtures do you refer to ? My intention would be to build in the washout as the wing is assembled. Thanks.

When the cover with coatings is done the wing remains sightly limber and the washout goes in without complaint by adjusting the rear strut as described in the Milholland text.. The wing really stiffens up when the jury struts go on - another good reason to put jury struts on your build - you will be pleased with the overall strength in the build - ie the jury struts effect the rigidity of the fuselage too...
 

[scottiniowa]

Scott in Iowa said...

"I didn't answer anything to the washout question...  Recalling the great amount of racking involved in getting the diagonal in place, should indicate what can be done.  Building this in, is very very hard...I would be the last to suggest to give this a go, as the required stiff fixtures on each are a must...and seldom on hand."

Scott, could you please elaborate on your statement above ? I'm wondering what pitfalls concern you and I'm just trying to learn here. If you build the whole wing flat, there's going to be all the diagonals, braces etc. to be built in and finally the nose D ply to lock in everything. Everything has to be squared for sure during the whole process. To build in the 2 degree washout, the rear spar at the outer end will need to be jacked up about 1 inch. All else previously mentioned will need to be adhered to anyway. What stiff fixtures do you refer to ? My intention would be to build in the washout as the wing is assembled. Thanks.

Perhaps a better explanation and I will just do this in a what is perhaps a blunt way, but very willing to listen to ways that work better.


1st- when building your wings,  you have your front spar and your rear spar, with the ribs  installed.  (Note: not nose ribs or certainly not leading edge skin) everything up this point is done with your spars held flat or all sides parallel- With this so, you can precisely measure your diagonals and then Rack (twist) your wing  to get them in place.  i.e. read page 7 on XL plans. 



Check for square- Everywhere-   READ - NO washout is held.  



You can install your trailing edge and then the double end ribs strip (both ends)



Maybe there are some builders that have figured out how to hold everything in place with 2 degree washout, but NOT needed nor worth the hassle at this stage.   Remember to achieve this, you would have to hold one end of trailing edge DOWN and the other end UP and not let them move EVER during the assembly. A tuff deal for anyone building one plane.



then nose ribs and leading edge skin. 



The instructions might jump around a bit here, but when you get the wings done but not covered, you can then rig the plane struts,  with dihedral set with the front strut, and then the washout with rear strut.  (ie. twist) page 8



Doing the final rig check as on page 10,  then ready to cover...  



Again, I am perfectly willing to be corrected, but if the building method requires even 3-5% more labor with the same results, plus the similar amount of brain time... I am not willing to do..



hope this helps  to explain better what I meant and why.

[scottiniowa]

Guess I screwed up my type fonts, but you'all be able to figure it out.

cheers