(Think Musically from your Childhood) - This is the Way We Wash Our Parts, Wash Our Parts, Wash Our Parts..........

Due to the unseasonably warm weather over the holiday week here in Denver, and the fact that I managed to take some much needed time off from work, it was time to get back to business in the airplane factory once again. Those of you who have followed my blog in the past have undoubtedly read the following phrase many times: "Wash, Rinse, Repeat.."

Well this time I mean it quite literally. Today was washing day - not for my clothes, and not for my car (although both are sorely needed) - but for my wing ribs that have been sitting patiently in their scuffed up state, just waiting for final preparation steps to be taken to get them all cleaned and primed. The mission for today was to wash all of the main wing ribs for both wings (28 in all) with my usual mix of warm water and regular Dawn dishwashing liquid. I also wanted to clean the two end ribs and prime them so that I could re-attach them to the main wing spars and remount them back on the wing stands.

I am happy to report that I managed to accomplish both goals today in our lovely 60 degree weather.

Here are some pics:

First are the two HD buckets - one with the detergent water,and the other with the rinse water:

Now also for those that are aware of my trials and tribulations this year - you know that I had to deal with two bathroom remodels this year. The upstairs bathroom now has a much larger new bathtub. As I began to plan for this washing and rinsing task for my wing ribs, I briefly thought about using that new spacious bathtub for this task. It would certainly make easy work of the entire process for washing and rinsing all my wing ribs.I stopped short of following through with this thought when I realized that the new tub is not cast iron, but is fiberglass, and it would not take much fora piece of sharp metal to cut right into the tub and cause all sorts of additional pain and suffering that frankly I just don't need right now. So I quickly got that idea out of my system and filled up the HD buckets instead.

The idea was to wash them, rinse them, and set them somewhere to dry. Here is my jury-rigged drying table made up up spare wood and two saw horses - very high tech indeed!

And another showing the operation in full swing, including my new priming table with the two end ribs on top:

And another shot of the two end ribs after applying the NAPA 7220 self etching primer:

And then finally, if you have any doubts about the need to thoroughly clean all of you parts before you apply primer, just take a look at this next pic of what used to be clean, clear water!

The amount of residue and grime just from the washing process is amazing. Even more amazing is the final part of the process which is cleaning each dried rib with a microfiber cloth and acetone (or your favorite carcinoginic cleaning chemical). Even more grime get lifted from this process, if done thoroughly and correctly. It is not inherently difficult - just time consuming. I still need perform the acetone cleaning step forthe remaining ribs, but to have them all initially cleaned is a major accomplishment for me, so I will take it. One other side note about all this. Once you get to the rinse and acetone stages of this process, you need to wear protective rubber gloves to prevent depositing oils and grime from your own hands back onto the parts. There is nothing I hate worse than having to re-clean something over again, so I always keep a large supply of rubber gloves handy. I think I may have gone through about  8 pair for this little session today. I changed them to a dry pair to perform final drying of each rib with a clean, dry cloth, and then again just prior to applying the acetone. Seems to work pretty well for me.


It felt good to work on the plane again - even if I am still not quite ready to rivet some parts together...

It's a funny thing about this airplane building business.........

Sometimes you will rack your brain for days trying to come up with the ultimate solution to a problem. Sometimes it will lead you down a path where you end up thinking that thereis just no way to accomplish what you are trying to do. And then sometimes, when you least expect it, a light bulb goes off in your mind, and you finally realize the solution to your problem.

I have had many such moments while working on my plane, and I expect that I will end up having many more. For months I have been mulling over the best and safest way to make a modification to my leading edge to make a small portion of it modular and removeable so that I can interchange them with the "fun"one and the "normal" one. I have struggled with many safety-related issues, including introducing weakness in the structure at a critical location along the wing, and disruption of normal airflow at a critical point over the wing, and so on.

The other evening I thought I had come up with a sound solution that involved a small, built up leading edge section with some span-wise support baffles or spars. Ithought I had it all worked out - - right up to the point where I suddenly realized that my grand solution was going to result in a very small sliver of wing skin on the inboard side of the leading edge of the wing, right where it attaches to the fuel tank skin by using a .032 inch thick joiner plate. I realized this as I was staring at one of my many drawings of this modification. Sadly, I also realized that this probably was not going to work very well, and I headed off to bed with my head hung low, with a thought that maybe I was not going to be able to do this safely after all.

Then, right as my head hit the pillow, I had an epiphany. I know how to spell that fancy word because I have had several of them during the build, and you just have to get to a point where you at least have to know how to spell it - even if you don't fully understand how or why or when they occur. I suddenly realized that all I needed to do was take a formed sheet of .032 2024-T3 sheet, and replace one of the W709 wing ribs with one more W408-1 wing rib, and use this as a kind of undergarment support skin in between both ribs. I can then apply the top skin section directly over the supporting skin underneath,and screw it down with as many nut plates as are necessary to secure the entire thing to the leading edge of the wing.

There I was, all but ready to either face defeat, or succomb to fabricating a rather complex rib-supported small LE wing structure, when all I really needed to do is to replace the W-423 Joiner plate strip with one contiguous piece of .032 sheet aluminum between the two W-408-1 ribs. The hardest part will be forming the leading skin,but I think I have plan for doing that as well. The full "under sheet" of aluminum will slide underneath the leading edge skin where it can be riveted in place to the two ribs and the top and bottom wing skins. Then I just simply need to detach one leading edge section, and replace it with the other one whenever the need arises - completely and easily interchangeable.

Of course I will still need to build a mockup, and perfect my fabrication technique for bending the LE contour, but the important thing is that I now know that this is do-able, that I will not sacrifice strength (in fact I will probaby enhance it), and that I will not negatively affect the airflow over that section of the wing. It  will basically fit like a glove over your hand and just slide right into place - easy-peazy. All it will take is a properly sized piece of .032 aluminum sheet, two W408-1 wing ribs, and a healthy supply of nut plates.

I will eventually have pictures  that will show the process I am describing in the weeks to come. At least I now have a solid plan to make this happen, and that makes me very happy. You just never know how or when some of these things will come together. Sometimes it happens when you least expect it. All I can tell those of you that may be facing the same challeges with your build is that you need to adopt an attitude and a way of thinking that can be best-conveyed from a line from the movie Galaxy Quest: "Never give up, never surrender!!!" Just keep pluggin along and eventually you will figure it all out, even when you think that there is no chance that you ever will.

Capturing some Measurements of the Leading Edge ribs, and dealing with yet another trategy a little too close to home

Today I got to experience the shock and terror that a parent goes through when you hear that there is a school shooting in progress, and that your child is currently on lockdown. Thankfully my son was not at the same high school where this trategy unfolded, and we got him home safe and sound, but we all know several families with kids that do attend that school, and my heart goes out to each and every one of them.

This year just really needs to end soon - I don't know how else to put it - there has just been too much shit this year. I have never been very superstitious, but I am coming to believe more and more that the number 13 is nothing but pure bad luck, and perhaps it even holds a bit of an evil stigma with it as well.

Please pray for the 15 year old girl that is still clinging to life in critical condition tonight in a local hospital. That's about all I am going to say about this.

Since building the plane definitely serves as therapy for me in a number of different ways, I decided to try to focus my attention on getting some measurements for the leading edge ribs for the mod. So I took a W408-1 L rib and a flexible sewing ruler and recorded the followingmeasurements:

The reference point at the front of the rib for all flange length measurements is the separation point between the upward and downward facing flanges. That is the starting point for all of the flange-length measurements that I took:

Upper flange length (front to back full length): 18.5 inches
Lower full length flange: 17.75 inches
Reference line for nose rib separation: just aft of the vertical portion of the "T" web stiffener in front of the first lightening hole

Upper Flange length from nose to reference line: 4 1/8 inches
Lower flange length from nose to reference line: 3 5/8 inches
Straight line measurement from the nose reference point to the edge of the vertical stiffener:
2 13/16 inches

Distance between the vertical stiffener and the stiffener forthe first lightening hole (at closest point): 3/4 of an inch

Straight line measurement from nose reference point to the rear of the stiffener for the first lightening hole: 7 3/4 inches

Straight line measurement from nose reference point to forward line of the rear vertical stiffener: 8 22/32 inches

Upper flange measurement to the forward line of the rear vertical stiffener: 10.25 inches
Lower flange measurement to the forward line of the rear vertical stiffener: 9.5 inches

Minimum distance between the rear edge of the first lightening hole stiffener to the forward edge of therear vertical stiffener: 3/4 of an inch

These are the measurements I need to deal with when figuring out where to cut the separation line for the modular leading edge section.


More later...

More research for the Wing Leading Edge Mod

As I previously posted, I think I have made a decision to construct a removeable short nose section of the leading edge of each wing to make a completely modular, removeable section of the wing leading edge. Last night I decided to do some research on some P-51 web sites to try to find a drawing  or somthing that would show the internal wing structure, especially around the machine gun ports. I was pretty certain that there was an additional short spar in between one or two of the LE ribs to serve as a support for the gun barrels and provide some extra strength to the bay in which all the guns reside. I did this to tryto determine if I would need a similar short spar in between the two ribs that form the edges of the bay that I will use for my mod. Then it turns into an analysis to determine if I need a spar for the removeable section,or if I only need a spar in the location where the removeable section will detach from the ribs on either side and the wing skins on the top and bottom.

If I do decide to use a spar for the removeable section, then there is the question of what thickness of aluminum to use. This then led me down apath of taking a look at some builders that have modified their aircraft to incorporate some integral auxiliary fuel tanks into the leading edge of the wings. Ron Duren and Mike Rettig immediately came to mind. I had not visited Ron's site for long time, but I knew that he was still chipping away at finishing his RV-7. I was pleasantly surprised to find a recent post wherehe talked about finishing up his wiring and then being ready for a first engine start soon.

I was also able to dive into his blog to find all of the detail around the Tuckey-Duren Leading edge aux fuel tanks that he built. Hopefully my mod will be bit simpler, but I will most likely need to fabricate my own spars, and that means precise bending of the flanges on all 4 sides - yuck! This becomes even more complicated bythe fact that there are lightening holes on the ribs on both sides, and stiffener indentations that firther restrict where the flangesof the spars can attach to the ribs. I could replace the LE ribs with end ribs for the fuel tanks, which have no lightening holes. THis would make it easier to place the spars where I want to put them,but the problem with the tank ribs is that they are shorter than the LE ribs since a baffle plate is used to seal the back of each tank, and this baffle plate sits forward of the main wing spar by a couple of inches. I could probably modify those ribs by extending the length with another piece of aluminum, but that leads to more structural strength questions.No matter what I decide to do, I will always have to takeinto account the effect of this mod on the forces of shear, tension, and torsion that may be applied to the wing under a variety of different flight conditions.

I must continue to resist the urge, no matter how great, to experiement to the same great degree of trial and error engineering that the Wright brothers must have had to use. IOW,I don't want to just slapthis together and then go try it out, even though the Experimental Aircraft Certification category basically allows me to do just that. I value my life and the lives of others just a little to much to be that brave. (read stupid, bold, etc.-reminds meof the old saying:

"There are bold pilots, and there are old pilots, but there are no old, bold pilots" - I think you get the point.

Anyway, I am taking fine measurements of everything right now so that I at least I will know the dimensions of all the parts I am going to need for this little project. Even though I am not slamming rivets just yet, it feels good to get back into the businessof designing and building an airplane.

How to work on the plane when it is too cold to work on the plane...

Well the weather decided to show up right on schedule. Just when I need some fair weather to finish cleaning and priming my wing ribs, a large arctic blast shows leaving several inches of snow and below zero freezing temps - about normal for me.

Since I have no desire to get my hands wet in a bucket of luke-warm water to wash freezing cold aluminum wing ribs, I decided to find some research work to do to kill some time while this ridiculous air mass slowly moves out of town. So my thoughts turned back to my LED light machine gun project, and how to design the removable section of the leading edge so I can interchange it with the gun assembly and a "normal" clean leading edge.

I was planning on doing the whole thing in fiberglass to avoid removing any metal from critical sections of the wing, but themore I have thought about it the more I do not like that idea because it modifies the airflow at a critical location on the wing to the point where it may affect the function of the inboard section of the aileron, which is not good. My technical counselor got me thinking more about that when he started asking me how I was going to address any fairing that I may need to make to blend the part into the top and bottom skins of the wing.

So I started thinking about a different solution that does involve cutting off the rounded section of the leading edge in between the first two nose ribs of the leading edge where the fuel tank ends and the leading edge begins. To avoid getting into too much detail it will involve ordering 2 more 408-1 ribs for the left and right wings, new .032 inch thick strips of aluminum to make a slightly wider joiner plate than normally called for, some additional sheet aluminum for making the LE skin sections and  short spar sections, and some additional stall warning mounting bracket nose rib sections. I am also going to order some Duckworks blank template landing light kits, hoping that the cross spars in those kits have top and bottom flanges that actually touch or support the wing skins. I cannot find any pics from other builder logs that clearly show the top and bottom flanges and how or if they support or touch the top and bottom wing skins, so I will just haveto order some and find out for myself I guess.

This first pic shows what a new scotch brite pad looks like after using it to scuff all of the main wing ribs. The new one ison the left and the 2spent ones are on the right. It took 2 pads to scuff all main ribs for both wings.It will probably take at least one more to do all of the nose ribs:

Next is a pic of my lovely drawings for the leading edge mod that I am about to undertake:

I have ironed out most of the details of this mod, but there are a few critical elements where certain parts have to be sized to exact measurements, and the more I have to measure and apply the math to properly bend a flange to a precise dimension, the less likely it will happen. So if I can use some prefabricated parts to do at least part of the job, then that would be a good thing. Hopefully this will come together well, but I need to order some parts first, and then wait for warmer weather. Ho ho ho.... :(

Wing Rib Prep Cont'd, and the loss of another good friend.....

I managed to finish scuffing the main wing ribs for both wings. In total I think this took me about 8-10 hours or so just to scuff and deburr the 28 main ribs (14 per wing). The last two ribs are the end ribs that are used to support the wing spar on the wing stands, so this meant that I had to remove both wing spars from the stands, remove the end ribs, and detach the angle mounting bracket from each rib. The leading edge ribs still need to be scuffed (14 more of those to do).

The next steps are to clean and prime the two end ribs so that these can be remounted to the wing spar so I can put the apars back on the wing stands. In fact, once these are primed I think I can go ahead and rivet them to the wing spar. The cleaning process is a bath in warm water and original formula dawn dishwashing detergent, followed by a deep cleaning with acetone and a micro fiber cloth.

For the primer I am currently thinking about using the NAPA 7220 from the spray can instead of the two part epoxy primer - mostly for time saving reasons, and because my two part primer has been sitting around outside in the garage for a long time and may now be unusable, and because the weather is expected to get colder next week.

And as if there isn't enough sad news in the world today, I just got word that another very good friend and Civil Air Patrol acquaintance John Butler has passed away. I spent a lot of time in my last several years of CAP service working with John by conducting a variety of different training courses for the Jeffco Senior Squadron. John was a great guy and he will be sorely missed. John had some medical issues but I don't have any details yet. All I know for sure is that at least he did not parish in an airplane crash. Rest in Peace John - Lord knows you have sure earned it.

This year just can't end soon enough for me.....

Scuffing alclad

Managed to start scuffing wing ribs after a long respit from building the plane. For me this takes about 10-15minutes per rib. Since I love doing the math for this kind of stuff just so I can realize just how much additional work I still have to do:
1. Each rib has 2 sides, a front and rear flange,and top and bottom flanges, and each of those have 2 sides. That means each rib has 10 sides of metal that have to be scuffed and made ready for primer.
2. There are 14 main ribs and about 7-8 nose ribs for each wing. Allof these have to be deburred, scuffed, cleaned, and primed. Needless to say this process takes several hours, or the equivalent of several days, for me to complete.

All but one of the left wing main ribs have been scuffed with a scotch brite pad. The one that remains is the one that the angle bracket is attached to on the very end which is still supporting my wing spar in the stand. I will have to remove the wing spar from the stand, disassemble the wing rib from the angle bracket, scuff it, clean it, and prime it, and then reassemble it all and reattach it to the end of the spar, and remount the spar back onto the stand.

The right wing main ribs are next, followed by the nose ribs for both leading edges. I have also had to perform the final edge deburring on the rib flanges on most of the ribs where they split into different sections that attach to the main wing spar and the trailing edge rear spar. There are small burrs on most of these separated flanges that have to be cleaned up. I used a small file, 200 grit aluminum sand paper, and the sctch brite padto clean them up. Many of the flanges had raised edges or small burrs and these will just eat away at the metal they are attached to if you do not clean them up.

At least I made some progress. My goal is to have all the main ribs scuffed by the end of the weekend.

On another note, I have come to realize that this "small" project of mine will most likely take me on the order of 10-15 years to complete. The number and size of the ongoing domestic interruptions, and the need to finance college expenses for 2 kids for the next 5.5 years are all taking a toll on me. I still see myself completing the project someday, but it certainly will not be completed completed in the 5 years I had originally hoped for. Not much else to say, except that life sucks sometimes.

ON that note, it is a sad day today after learning that the president of EAA Chapter 43, David Biesemeier, died Wednesday after taking off in his experimental aircraft from Erie/Tricounty airport. I had met him a couple of times and he was a really really nice guy. He will be missed. The details as to the actual cause are still not known, but there is some indication that he may have lost a wing or experienced a major engine malfunction or a possible breakup in flight. The media, as usual, is all over the place with their reports right now, so we will have to wait for the NTSB report to get anything closer to the truth.

I am finding that at my age I have started experiencing the loss of an increasing number of friends and loved ones for a variety of reasons. I guess this is a sure sign of getting older but I have to say that this just really sucks. We lost Alex to cancer just a couple of weeks ago - the boy who wanted to be a pilot that we were thankfully able to send to Oshkosh. Cancer sucks, dying in an airplane accident sucks, death sucks. There are too many people from all generations whom I respect dearly and from whom I have learned so many things that are no longer here,  and that sucks too. Sorry to rant, there has just been too much of this happening lately, and its a little hard to digest.

Anyway, hopefully I will be reporting more plane building progress in the coming weeks.