Counter sunk the Pitot Tube Mast and Checked out the LE from the Inside

Since I received the AN507 6R4 screws from ACS, I decided it was time to do the deed and countersink the mounting holes in the mast to accept the new screws. I had an opportunity to practice this a bit before going to town on the real thing by using the half inch of mast material that I cut off as described in my earlier posts. Some of my pics turned out really blurry so I won't show the close ups.

To countersink the mast mounting holes I did NOT use a microstop countersink tool, as this is next to impossible to use since you are countersinking a hole on a curved surface. Other builder sites have reported that it is almost impossible to get a totally good countersink on these mounting holes because of the curved surface of the mast.

So I did everything by hand by using 2 different deburring tools. I started by using my single flute deburring bit in my electric drill. I made sure that the deburring bit was angled in the same direction that the original hole was drilled, and that the bit was as square to the hole as I could get it. Once the countersink was started and I could not go any deeper with this tool, I switched to my larger 3 flute deburring tool that has a larger countersink bit on it.I removed a little material at a time, maybe only 3 light turns each time, as I got closer to the final depth for each screw. The last thing I wanted to do is make the countersink too large for the screw head. After countersinking each hole I would remount the new pitot tube into the mast and tighten down each screw to check the depth, and then carve out some more metal if necessary and do it all over again.

Practicing on the scrap piece of the mast helped, because that allowed me to get a feel for what it would take to get the right depth for each screw. Here are some pics of the tools used and the new screws  think I have some more work to do on one of the forward holes, but the rest of them seem pretty good to me.

Next is the work on the LE. I removed all clecos attaching the LE skin to the Wing Spar flange, and then I removed all clecos attaching the rear LE rib flanges to the wing spar web. Note to self, remember to apply all these clecos from the rear (bottom) of the wing spar web, and NOT through the top or front of the web. When I attached the LE to the modified W408 rib it was already attached to the wing spar and I had mounted the clecos on the top or front side of the wing spar web. The goal for this removal was to remove the entire LE assembly from the wing spar, leaving ALL ribs and the subskin clecoed in place so I could inspect the new holes and clearance on the edge of the rib flange.

To do that I was faced with trying to figure out a way to remove 3 clecoes attaching the 408 rib from the wing spar web. I really had no other choice other than to remove the clecoes holding the LE skin to the 408 ribs again, but that would mean starting all over again, so I got creative and figured how to get my hand inside the lightening holes of both 408 ribs with the cleco pliers in hand, and then working the pliers with one hand by reversing the pliers to face the clecos, and feeling my way around in the blind until I new I had attached the pliers to each cleco. The clecoes are hidden from view so all of this has to be done by feel. I managed to get each one undone, but I really do not want to do that again. SO next time all LE attach clecoes will be inserted into the ribs from the rear (bottom) of the wing spar web.

With the fully assembled LE finally off the wing, I was able to check my handy work. Here are the pics of the top and bottom rib flanges where I had to trim away some of the rib flange to allow clearance for the shop head of the rivet that will go into the closest hole (where the cleco end is currently. At a galce it looks like the shop head of the rivet will clear the flange, but I need to make sure it will clear AND not rub against it, so I think I have just a bit more filing to do, but its real close:

This next pic is a bit bright due to my flash from the camera, but it does show some detail of the inside of the LE area that I have been working on:

You are looking at a close up of the bottom rib to LE skin flange with the LE laying on its side. You can see the area where I trimmed the rib flange for the clearance for the original rivet hole that will go through the outer skin and the sub skin only. (Last cleco on the right). The next cleco to the left is the new rivet hole that I drilled that will attach the outside LE skin, subskin, and rib flange (3 layers of metal). I can also see that I have at least the required 2xD edge distance, or in this case 1/4 of an inch from all sides of the flange (rear, outside edge, and inside bend radius).

The rib flange is sitting on top of the extended subskin, and the outer LE skin is sitting under the subskin.So with a little more filing I think I will have sufficient clearance for the shop head of that right-most rivet hole that normally would have gone through the final hole in the W709 rib, but since I am not using that rib any longer this is the change that I had to make.

After I get this clearance issue done I can start prepping the ribs and outside skin for primer, and then I have to rivet the rear rib flange additions to the web of the modified 408 rib (The six holes at the top of the above pic, plus the ones for the other side of the rib). Then I get to make even more critical measurements on the subskin so I can start trimming that up to its final form. Hopefully the pics  provide a bit more clarity to my explanations about what I doing here. Getting there......

KPR.

Pitot Mast trimmed and new screw holes measured, drilled and tapped

I'll add some pics tomorrow. After getting some feedback from VAF folks and from Vans, I determined that I could trim about .5 inches from the SafeAir Pitot mast to remove the old screw holes and re-drill new screw holes to mount my replacement heated pitot tube from Dynon. Took about 2 hours total to gather and setup the needed tools, cut off the portion of the mast, file it smooth and flat, measure the screw hole locations, and drill and tap the new screw holes.

Tools used were my band saw, my disk sander, a hand-held flat file, my scotch brite wheel, metal straight edge/ruler, hole punch, ultra fine blue Sharpee,  my cordless drill, electrical tape, 3 in one oil, the following drill bits: #51, #36, and 9/64ths,  a 6-32 tap with small handle, my table vise, 3 blocks of wood, a small level, and my old pitot tube. Who would have thought that so many tools would be needed just to drill and tap a few screw holes!

Thanks to my friend and fellow RV-8 builder Steve Riffe, who is about to finish building and take his first flight in his new airplane, I used his procedure from his kit log to mark, drill, and tap the new screw holes, and all went pretty well.

This time there was no drill press involved. I marked line around the mast that would ensure that the old screw holes would be completely removed. I had to dust the cobwebs off my band saw and set it up for the cut by using a small 2x4 piece of wood to set the odd-shaped pitot mast with its mounting flange onto so that I could run the wood and the mast through the saw. The cut was raw and somewhat jagged, and would require some file-finishing, leveling, and smoothing before it would be ready for the new screw holes and the new pitot tube.

I tried to use my disk sanding wheel on my electric sander but it was so clogged with old wood dust that this was not very effective. The end result was a smoother edge on the newly cut mast, but it was not very straight. Out came the hand-held flat file. I used the level and eyeballs to check for flatness of the newly cut edges, noted the high and low spots, and started slowly running the file over both sides of the top of the mast. I managed to get it very flat and square again, but also know that I had file marks that I would need to get rid of, so over to the scotch brite wheel I went. I was able to polish the file marks out to remove any potential stress risers on the end of the mast. I then used the old pitot tube to trial fit it into the mast. this was easier than using the new pitot tube because it no longer has the long tubes and electrical wiring in the way, since all this had to be removed as part of the pitot replacement procedure from Dynon. Never thought I would be using it again, but it came in handy for trial fitting the pitot into the newly cut mast.

Here is a pic that does not show all of the tools I used, but close:

Once I was satisfied, I replaced the old pitot tube with the new one, verified the fit, and taped it in place on the mast. Then I measured the same 11/32 inches at the base of the pitot tube mounting flange and re-verified the marked lines for the proper location of the 4 holes. I put tape on the end of all drill bits so that only 1/4 inch of the bit was exposed so as not to drill too deeply and damage the tubing internally. I then used the hole punch to set starter holes in the mast for the drill bit.  I sandwiched the tube and mast assembly between two small pieces of wood and secured the assembly in my table vise, being careful not to apply too much pressure to avoid damaging the pitot tube. All you need is enough to hold the assembly so you can drill the 4 mounting holes.

I started with the #51 drill bit to drill pilot holes into the pitot tube. Wow, say that 5 times real fast! Here is  a TIP: When drilling, the metal extensions inside the pitot tube that provide the material for the screw threads extend inward only so far. If you have drilled what you believe to be 1/4 inches into the pitot tube and the drill bit has not broken through this material, keep drilling just a bit more until you feel the bit go completely through. Be careful not to go too far. Doing this ensures that the tap will be able to properly set the threads in the hole. When I did this the first time long ago I don't think I drilled one of the holes all the way through, and my tap then stripped several threads as I tried to force the tap to go in further when it had no more room to do so.

I did all the drilling by hand using my cordless drill, going slowly and ensuring that the bit was as level as I could make it, and that it also followed the contour the curvature of the pitot mast assembly. this is NOT a very easy thing to do because the front and back ends of the tube and mast are shaped like a big fat wing for obvious reasons. So the curvature is different from front to back. If you align the drill bit with the metal extensions in the top of the tube you will be fine.

After the 4 pilot holes were drilled I switched to the #36 drill bit and re-drilled the holes again. Once this was done the holes in the pitot tube were ready for the 6-32 tap. I did all that by hand as well, and even took the tube out of the table vise and held it in one hand while tapping with the other. I used 3 in 1 oil to lube the tab, and made sure I applied the tap a little at a time and then backed it out, cleaned up the sludge, and the tapped it a little bit more. I did this until I felt the tap free up, which is a sign that all the threads in the material have been formed properly.

The most concerning part of this process, which I have reported on in my earlier posts when I tried this the first time, was tapping the two forward screw holes. The tap has to extend rather far into the inside of the pitot tube to properly tap both forward holes, and the tip of the tap comes very close to the internal metal air lines that provide the airflow to your instruments. I am still concerned that the tap may have scored the front part of the front tubing, but I did not feel it hitting anything, so perhaps I am OK here. The tap is tapered on the front, so maybe that also helped prevent any compromise of the forward tub as well. All I know is that the tap comes really close to this tube by the time you have properly cut the threads on those forward holes, so be careful.

With all four holes successfully tapped, I final drilled the mast holes using the 9/64ths drill bit to make a clearance hole for the 6-32 x 1/4 inch long screws. I successfully screwed in all four screws and verified that they all tighten up as expected. YAY! no stripped threads this time! Then I removed the screws and place the pitot tube back into the mast and screwed them together again to ensure proper hole alignment through the mast and to re-seat the threads in the new holes. I am goin g to order specifically sized counter sunk screws from Aircraft Spruce and will counter sink the holes in the mast once I have those screws in hand. Right now I am using the stainless steel pan head screws that I had to trim down because they only come in 3/8 inch sizes and are too long. These add a small amount of drag as the screw heads stick out into the slip stream. I will now use the flush head screws now that I know this part of this tedious process is behind me.

The finished product, on a mast that is about a half inch shorter now:

The location of the screw holes also came out much more symmetrical than my first attempt. Its still not quite perfect but is much better than the last time. The inlet hole of the pitot tube ends up being 6 inches from the bottom of the wing - exactly where I expected it would be. I'm glad to get this small step completed, and hope I never have to do it again! I still have the tubes to trim, and tubing flanges and NPT hardware to set up, as well as mounting the tube to the wing, but that will be done later, after other wing assembly steps have been completed.

Remounting my replacement Dynon Heated Pitot tube

A very long time ago Dynon had some issues with their heated Pitot Tube probes where ice or water blockages were causing erroneous airspeed indications. Since Dynon's attitude reference is based on airspeed, this caused a number of different problems with their EFIS and autopilot systems. From some of the accounts that I read many of them were what I refer to as just short of loss of control types of events with the autopilot. This is not something I wanted to experience if flying IFR, or any other time for that matter.

They apparently found an issue with the location of their drain holes on the bottom of the tube, and after doing some robust testing came out with a redesigned pitot tube. I have not seen many flight reports since the new tubes were sent out to existing customers, but the ones that I have seen seem to indicate that the former problems have been resolved.

That said, I received my replacement Pitot tube a long time, and it has been sitting idle ever since. IN the past 2 weeks I have ben reviewing my blog posts and re-organizing my shop and getting re-acquainted with some parts that I had ordered for a variety of things. Among these are the bung kit for my future auxiliary fuel tanks, leading edge access hatch kit, LED landing, position, and nav lights from AeroLED, and the replacement heated pitot tube from Dynon.

If you search for the words Pitot Tube you will find a handful of previous posts where I performed the initial mounting of the tube to its mast. This did not go well for me the first time, and I plan to make sure it goes much better this time. The main reason for this is that the pitot mast that extends down from the bottom of the wing skin to provide clearance between the wing and the tube is a very expensive part that I do not wish to replace if possible. I messed up the mounting holes the first time and so I want to trim the pitot mast just a bit so I can redrill new holes.

I submitted a post to VAF to ask if there are any issues with trimming the mast below its original size. Airflow around the tube is a concern, as this is what is used to provide airspeed information in the cockpit. Click here to see the VAF post. If I can trim the mast down a bit I can redrill new holes and hopefully be done with that once and for all.

I've also got an order to aircraft spruce and Vans to make - time to start getting building supplies again. I am going to start with the pitot tube as a way to begin with a "small" project and then work my way back into the leading edge and fuel tank mess that I left almost 2 years ago. I need to make a decision about the fuel tank skin that messed up with a deep scratch made by a cleco while trying to force it into the skin and rib - not fun, and expensive if I need to replace the skin.

Like I have said before, I know exactly where I left off. it ain't pretty but I just need to tackle one problem at a time and move on. That is how you build an airplane one day.

Drillled and Tapped Pitot Tube and Mast

Man the last two days have been nerve racking. Most people write about these steps in their builders logs as though it is no big deal, but for me this task has to rank up there with all the tasks that I absolutely cannot stand  about this project - which includes the task of drilling raw holes in round or awkward shaped materials. I absolutely hate having to figure out how to jig, clamp, align, and whatever else that has to be done to do this right. You know, all the gory details that nobody ever seems to talk about in their build logs.

For starters, the shortest screws I could find locally were 3/8 inches long, and I really needed 1/4 long mounting screws. The solution - A dremel tool with a cutoff wheel, and a clamp. I started out by using one of my plastic squeeze clamps, holding it in one hand with the dremel tool in the other. This worked great - right up to the point that the heat from the screw started melting the plastic holder. So I stopped that foolishness to think of another way to hold these screws so I could cut off the last 1/8 inch. I have done this numerous times when building RC airplanes over the years, so this technique was nothing new to me - just that the length of the screw was  a bit shorter than I was used to working with. What I finally came up with was using 2 thcik wood blocks, adn inserting the screw head in between each block and clamping it tight in my table vise so that the screw head would mash down slightly into the wood. This made a stable way to use the dremel to cut off the ends of each screw. I then got out an 1/8 inch thick piece of aluminum from my trim bundle, and drilled and tapped the same hole that I was about to drill and tap in the real thing. At least I remembered to do something right. That all went as expected, and after a small amount of filing on some of the freshly cut screw ends, each of the 4 screws inserted cleanly into the threaded hole.

Now to drill the holes in the assembly. Silly me thought that I had it all figured out. TO do this right, it requires drilling somewhat precise holes, so that meant it was time to use the drill press for this. UNfortunately that means clamping and positioning the table in just the right spot so that the hole is drilled correctly. Here is a shot of my arrangement, complete with wood blocks, a drill clamp, and my #40 drill bit with a drill stop positioned so that it drill no larger than a 1/4 inch hole. It all looks pretty lined up too.....

By the time I had taken this pic, I had already drilled the two rear holes. That worked out ok, except for one thing that I will show in a bit. For the rear holes, the assembly was able to be clamped solidly into position without moving. To amke things a bit easier, the rear holes are drilled in a location where there is very little curvature to the assembly. However, from the above pic, you can see that when you drill the forward holes, this becomes a bit of a challenge. What I found was that the assembly would not clamp down tight in this position duw to the extreme curvature of the mast. Instead, the forward face of the assembly kept riding up on the wood block with each turn of the clamp handle. The one thing that it was doing was placing the assembly at the correct angle for the drill bit. It worked great for that. I thought I could just hold the part steady with my left hand while I ran the lever on the press to drill the hole.

I should also mention that I set the stops on the drill press in addition to using a drill stop on the drill bit to ensure that I would not drill the hole too deeply. I also secured the mast and the tube with gorilla tape as shown in the above pic. SO, everything was in good shape, right? WRONG. As soon as I turned on the drill press the clamp vibrated lose and the assembly would shift out of position. So much for that idea. I was not about to spend frickin hours making a jig that holds the pitot in just the right position to drill these stupid holes.

Too bad, because it sure looked like it would work great - here is another pic - everything looks spot on lined up. Note the angle of the pitot tube that is required to drill a straight hole through the mounting material in the inside of the pitot tube.

So at least I had the good sense NOT to try to drill these holes using this method. I stopped for the night so I could rethink this and figure out what to do.

So shift forward to today. The next pic shows what I basically came up with - take the assembly outside to the vise, clamp it upright against the two wood blocks, put the #40 drill bit in my cordless drill with adjustable speed trigger, lined up the angle as best I could, and drilled the first pilot hole. Then I turned it around and did the same thing on the other side. I did NOT use my air drill for this - the trigger is too unpredictable and hard to control. I needed to start this slow and keep the drill steady all the way through.

After that was done I changed drill bits to a #36, and drilled through each hole again to get to the correct size for tapping the 6/32 threads for the mounting screws. Then I ran the tap through each hole. In short, I free-handed the stupid holes. Other build sites I have visited where folsk are using their drill press actually don't seem to be doing much better than me. Several of them show holes that are drilled that are not really at the correct angle as determined by the aluminum flanges on the inside of the pitot tube. WHne you see the screws being inserted in the pics it clearly shows that the holes are not aligned correctly with the face of the mast.

For the #36 drill bit as well as the 6/32 tap, I used some electrical tape wrapped around the shaft to serve as a drill stop of sorts so that I would not risk drilling into the stupid air lines in the pitot tube. The rear holes are no problem, but the forward holes will get you into trouble if you run the drill bit too deep.

The above pic hints at my next problem. A couple of the holes were bottoming out on the tap - the reason - the hole was not drilled quite deep enough for the tap. A quick look at the tap revealed the problem. The tip of the tap barely has any cutting threads on it, and tapers off quite sharply at the tip. This basically means that the tap probably requires at least 1/16" more distance to allow the cutting threads to properly seat in the material all the way through the hole. I thought I had this all worked out by just continuing to run the tap alittle bit further, that is until I got to the forward hole on the left side.

The other holes had been drilled all the way through the aluminum flanges on the inside of the pitot tube - all of them except the one on the left front hole. When I tried to torque the tap a bit further in that hole, all of sudden it just let go - no threads, no resistance. Yup, I managed to strip the #$%&;^&;*^% hole! What an ass I am sometimes. That was about as stupid as it gets.

Out came the #36 drill bit to finish drilling through the material, and then I reran the tap through the hole. Bottom line is that this hole only has about 1/8 inch or less of viable threads that are actually grabbing and securing this screw - not good. But at least it does grab. Something tells me that before this is all done I will probably be resizing that hole for a #8/32 screw.

And now for the finished masterpiece. The left side with mounting screws inserted..... and NO I am NOT going to go through the trouble of countersinking these stupid things. Enough is enough already. I'll take the drag penalty.

...and then the crappy looking right side.

Note the mis-aligned screws. The sucky part is that this actually happened on the drill press. I must not have had the first rear hole lined up in quite the right spot, and so it got drilled slightly lower than where it should have. The other 3 screws are relatively lined up with each other. This is purely cosmetic, but pisses me off jsut the same.

SO there you have it. IF anyone can royally screw up such a simple task, it is surely me. At least the damn thing is drilled and mounted. I can't wait to see how bad I can screw up the mounting the mast to the wing spar - stay tuned for that episode of dumb and dumber.

OK, I need to go cool off now, this has been an exhausting and disappointing couple of days. I bought a "kit" for a reason. If I would have wanted to spend all my tine laying up undrilled holes in all sorts of wildy contorted non-linear objects, I would have built it from scratch. For me, this process ranks up there in the top 5 things about this project that I hope I never have to do again. I sure hope that I did not drill too far into the pitot and either scar the tube or puncture it outright. Initial "blow" tests through the line seem to indicate everything is working correctly, but only time and repeated wear and tear will tell, since you can't see any of the tubing buried underneath the silicone deep inside the pitot tube....

Deburring Rib holes and Marking Pitot Tube Mounting Holes

Well I was finally able to stop researching and get out in the shop to do a little metal work for a change. A rough few weeks at work, weather, and a head cold have kept me pinned down a bit, but tonight I was able to do a few small things.

First, I was able to debur almost all the holes I had previously match drilled in the main ribs where they slide underneath the main wing spar flange. I deburred both inside and outside holes f the wing spar as well as the ribs. Now I just need to finish drilling and deburring all the wire run holes and hopefully I can move on the prepping them for primer.

Then I decided to perform the steps to mark the hole locations for the pitot tube mast. Neither the pitot tube nor the mast holes are drilled at all, so you must locate, mark, drill, debur, and tap the holes.

1. mark the center of ech screw mounting point of ghe pitot tube. This is identified by the 4 thicker areas of aluminum that protrude deeper into the top face of the pitot tube as shown below:

2. Carry the line down the side of the pitot tube and continue the line past the point where the pitot tube base widens out.

3. Measure the height of the recess in the pitot tube to the top of it. Mine measured about 22/32. I then took half of that value, or 11/32, and marked the pitot and mast accordingly. This will effectively put all the mounting screw at the halfway point of the mounting flange of the pitot tube.

4. Slide the pitot mast over the pitot tube. I also used electrical tape to fill the slight gap between the outer edges of the pitot tube and the mast - this is typical of the pitot and mast that I am using. Some use electrical tape and others use heat tape. All you are trying to do right now is get the pitot tube to snug up against the wall of the mast so you can drill accurate holes through both of them.

5. Transfer the vertical lines onto the mast, and then measure the 11/32 from the end of the mast on both sides and draw the intersecting line on each side of the mast.

I center punched the hole locations on the mast and decided to stop there for the night. My plan is to gradually upsize the hole to make sure that it maintains the correct angle based on the mount points built into the pitot tube. The last thing I did was to reposition the drill stop on my #40 drill bit to just over a 1/4 inch. The mounting screws can not really be any longer than that,or you risk drilling into the actual air lines or heating element inside the pitot tube. You can order either countersunk or pan head screws from ACS, or I was able to find some 3/8 inch long, 6/32 pan head stainless steel screws at  local hardware store that I plan to use for my setup. Lots of folks go ahead and get countersunk screws for this, but I just did not want to go through the trouble. Neither of the screw types sits absolutely flush to the round pitot mast, so I am ok with just using the pan heads for now.

And lastly a shot of the electrical tape wrapped around the mounting flange of the pitot tube:

The tricky part of all this is drilling the holes at the correct angle and depth. I plan to use my drill press for this so I can clamp the work at the correct angle and ensure that the drill bit will maintain a straight path into the tube. Will try to do all that tomorrow.

Researching Lights and Pitot Tube Placement

After receiving my new Dynon Heated Pitot Tube I started researching the placement of the pitot  tube in the wing, and looked at several builder sites to see exactly where they placed the pitot tube, and how they routed the airlines and electrical wiring for the heat controller. As I was doing this, I had a revelation of sorts that kind of concerned me just a bit. The reason is that it seems that most builders using the same components that I am using are locating their pitot tubes in the bay just OUTSIDE of the location that Vans uses for the stock pitot tube. The reason is that the location for Van's stock tube is in the same bay where the aileron push/pull tubes and the aileron belcrank are located, not to mention a possible autopilot servo and all the associated wiring that goes with it.


In short, this is a very busy and critically important bay in the wing that houses some of the most critcal flight components of the aircraft. So anything that may interfere with those components is a serious potential hazard. The stock pitot from Vans works in this location because it is nothing more than a length of 1/4 inch aluminum tubing bent to shape and mounted through a hole in the bottom main wing spar flange, and then routed through the holes in the main wing ribs back to the fuselage. It is mounted to the bottom spar flange so it is out of the way of the push/pull tubes and the belcrank. Unfortunately, a pitot tube such as the one I am planning to use will have to be mounted in such a way that placing it in this same bay could cause several different problems, none of which I am willing to expose myself or my eventual passengers to.



The general thought is to move the pitot further out on the wing to ensure that airflow from the fuselage does not introduce airspeed indication errors due to disruptions caused by the fuselage or the landing gear, etc.

All that said, positioning the pitot tube further outboard under the wing also creates a new problem. The problem can occur when the time comes to tie down the aircraft at your destination airport, either for a fuel stop or as you final destination. To do this, you have to rely on the tie down spots that have been positioned by each airport's FBO. The placement of these tie downs is up to the discretion of the airport operator, and is usually based on the types and even the makes and models of aircraft most frequented at the airport.



As I reviewed the plans, I started to realize that if I move the pitot tube to the next bay outward, there is a risk of a tie down rope coming into contact with the pitot tube. This is because the ties down ring will end up being inside of the pitot tube. I submitted a post to VAF to ask for photos from folks with a similar installation that shows the positioning of a typical tie down rope and the pitot tube after the airplane is tied down. What I found is that there is definitely a possibility of the rope interfering with the pitot tube and damaging it or even a part of the wing in the process, unless the wing tie down rope is positioned slightly forward. This may or may not be possible from one airport to another, and depends on several factors, such as position of the tie downs on the airport in relation to each wing tie down ring on the RV, and the position of the tail tie down point. The pictures sent to me in the VAF post pretty much tell the tale.



So, now the question is, what to do about this, if anything. Luckily today I think I arrived at a solution, while not perfect, is good enough for me and is one that I will implement when the airplane is ready to travel. Basically, what needs to be done is to find a way to extend the tie down ring a little bit more, so that the ring is just a bit lower than the lowest point on the pitot tube. The tie down rings are simply standard 3/8 inch eye bolts thatr are usually 2 inches in length. I googled for eye bolts to see if I could find some with longer shaft lengths that the typical 2 inch long ones at the local HD airplane store.


As luck would have, the first link in the search results returned a company that deals in exactly that, all sorts of different sizes and configurations of all types of different eye bolt applications. Therefore, my plan will be to carry these slightly longer eyebolt extensions with me on the plane, and any time I have to tie down at an airport where I have to be concerned about the clearance of the tie down rope or chain with the  pitot tube, I will just insert the longer eye bolts, and the problem should be solved.

Now I can proceed with installing the pitot tube in the outer bay without worrying about the tie down problems.



I have also spent some time reviewing lighting solutions. Duckworks has a lot of my attention right now, in addition to Aveo and AeroLED. I am starting to wane from any interest in AeroLED because they appear to be posturing themselves as a bonafied certified aircraft shop, with the experimental market as an after thought. Unfortunately the prices for their LED light solutions are also representative of that situation, and I am far from interested in spending 2000.00 + for a stupid outside light solution for this airplane. That is just absolutely absurd and rediculous, and anyone that pays that kind of money for something like that ought to be ashamed IMHO. I'll have more on the lights later on.

Aux Tank Inspection cover and Bung kit arrives

Received the external fuel tank access/inspection cover kit and the bung kit the other day from SafeAir1 . I just could not resist this bit o' fun by taking this rediculous robotically themed photo to show off the parts in the kits. The two round robot "eyes" are the bung flanges that will mount to the outboard ends of both main fuel tanks to provide the inlet from the aux tank into the main tank via the fuel transfer pump. The remaining robot parts are the back plates and cover plates of the additional inspection/acces panel that will be cut into the leading edge of the wing.

Next I set out to determine where to install the pitot tube. The builder is left with some decisions to make when deviating from the plans, but many folks have done this same thing prior to me so I am sure to make the right decision. One of the first decisions was deciding to keep the full length of the air lines extending from the pitot tube or not. They are too long to leave "as is" so you either have to bend them over or cut them down a bit. They also require you to flare the ends to accept the AN NPT hardware used to attach the colored lines from the SafeAir1 plumbing kit to the pitot tube.

UNfortunately I had never flared a metal tube in my life, so before I ruined the real thing, it was time to practice. I already puchased the Parker Rolo Flare Tool, and with te help of the instructions, I found some 3/16 inch OD aluminum tubing from K&S Engineering at the hobby shop to practice with. Although the OD diameter of the tubing is the same, the ID dimension is very different. The hobby shop tubing is very this walled - .014 inch thick aluminum, whereas the tubing on the pitot tube appears to be a bit thicker. Further research revealed that the hobby shop tubing is 3003 H14, while I think that the tubing they used for the pitot tube is 3003 0. Same alloy but a different hardness and thickness. The pitot tube appears to be a bout .025 inches thick.

My first attempt at flaring the ends "ended" in disaster - obviously I had to practice with this tool. It does not take much to create a good flare, ans since I was using tubing with a much thinner wall than the on the pitot tube, it was even more difficult to get a good flare without cracking the tubing. Here are some pics of my practice results after I finally got the hang of this tool:

First is pics of some tubing I found at Lowes airplane parts:

And next is the flaring tool. You have to purchase one similar to this because all aviation flares are made at 37 degrees. All automotive flaring tools are set to 45 degrees, and will not work with aviation-grade NPT plumbing hardware.

The above pic shows a locking flange in front of the hole where the tubing goes, butted up next to the business end of the tool that creates the flare as it is rotated inside the tubing. The locking flangen the left of the pic sets the correct depth of the tube by pushing the end of the tube until it hits this flange. Then, when the toll is locked into position, the locking flange slides out of the way of the flare bit, and you crank it down into the hole in the tube to create the flared end.

Here is a pic with the flange moved slightly out of the way:

And then finally the results of my practice attempts. The pics are blurry - could not correct that for some reason:

the last pic attempts to show some slight bumps on the outside edges of the flare. These were caused by the separation of the top and bottom dies, which are split in the middle. I am not sure if this means that I need to tighten down the dies a bit more, or if this is considered normal. The AN hardware fitting in the pic above that one seems to seat itself just fine. Problem is, you want to make absolutely sure that these are done correctly, or you will end up with leaks and possible failures - which is not good.

All in all I was satisfied with the results but it definitely has a certain feel to knowing when to stop cranking down on the flare bit, adn the prep on the end of the tube is absolutely critical as well. Any burs on the end will most definitely end up with a cracked flare, so care must be taken there as well. It was cool to see how this tool works.

Next post I will talk about my efforts to practice bending 3/16 inch soft aluminum tubing to shape with another bender tool I purchased. That experience was not as good as this one was - and I am not real happy with the claims made by the bending tool that I purchased that it will handle 3/16 inch tubing. After my experience I think that is a bunch of crap. Anyway, more on that tomorrow.

Finishing conduit holes in both end ribs

I removed the end ribs from boths main spars the other evening. I then marked the position for the last conduit hole in each rib, and I still need to finish drilling the holes. Once that is done I will take one of "money pics" of the build. By that I simply mean that there are few times during the build where some fairly interesting pictures are taken. One of those, in my opinion, is the pic that most people take once all the conduit holes are drilled, and they take a pic of the ribs down through the series of holes with the ribs all mounted on the spar. It is another one of those optical illusion pics that I like.

Last night I took the fam to the Jeff Dunham show here in Broomfield at the 1st Bank Center. It was a blast. I first became acquainted with him during first year at Oshkosh in 2009, which turned out to be the 2nd year in a row that he was performing at Oshkosh. I have mentioned before that he also has ties to aviation, having built his own kit helicopter.

He is absolutely one of the funniest and most talented vantriloquists I have ever seen. All the characters were there, Achmed, Peanut, Bubba Jay, Jose, Walter, and Little Jeff. He began the show, titled Disorderly Conduct, with an absolutely hysterical video where all the characters end up in the slammer, getting interogated by Jeff himself. Then he showed pictures from his childhood, and the show was made up of a mix of old and new material. I highly recommend going if you really like to laugh.if you have the chance.

Now for some really wierd and amazing facts that my wife just told me about as she was reading his bio online. He was born 4-18-1962, a day before I was, in Dallas, Texas, same place I was, and was raised by a Presbyterian family, same as I was. How bizarre is that! We could have been neighbors for crying out loud. One big difference is that he grew up as an adopted only child. Of course, he is also a rich and famous entertainer - yet another major difference. Still, it's nice to know we come from the same background.

Back to the build, we had a major snow storm blow through last night so we are now thawing out from that. So not much was done on the build today. I did spend considerable time researching some things in preparation for a rather large parts order I am about to make. Soon on the way to me will be the following:

SafeAir1 pitot/static line kit #1
SafeAir1 Pitot mast kit
Dynon Heated Pitot Tube and controller
SafeAir1 extended range tank bung kit for both fuel tanks.
Additional SB375-4 plastic snap bushings for RG400 antenna coax wire run and additional wire runs at the forward end of each main rib.
Possibly the SafeAir1 Fuel pump access/inspection hatch kit for the extended range tanks

I also managed to drill and debur all the forward flange rivet holes in both the right wing ribs and main wing spar, as well as the underside of the Lef main wing spar. I will still need to do all the holes for both end ribs. I confirmed from VAF posts that the SB375-4 will provide good clearance for the antenna coax. It requires a 3/8 inch hole drilled in the rib for a 1/4 inch ID hole for the wires/tubing, etc. I also need to call Vans again and ask about drilling the rib holes through the main wing spar flanges. Problem is that you have to drill and debur these holes BEFORE you rivet the main ribs to the spar, but the wing skins are not yet final drilled to those holes, which may cause the skins to be offset just a bit. This may effect the alignment/fit of the leading edge skins against the main wing skins, so I want to check with Vans to verify when exactly should I drill adn debur those holes.

I also researched the DuctWorks site and saw that they are selling a new round stle LED wing tip lite kit. Only problem is that they require a separate flash unit to allow them to wig wag, which ductworks apparently does not sell. Aero Led also has some new high briteness LED lights. I like the wing tip light concept because I don't have to saw out part of the leading edge wing skins for a leading edge type of mount, and it makes servicing the lights a bit easier as well, since all you have to do is remove the wing tip or just the lense cover. This makes installation fairly quick and easy I think.

I like the AeroLED lights because they come with wigwag functions build into the lights, so no separate flash unit is required. Still mulling all that over right now. I also saw a recent post of a comparison of LED, Incandescent, and HID light systems. I don't think that LEDs do all that well for distant illumination, but we'll see. I may still go with them because one of the new features of the GRT AHARS avionics is that they provide an option for a night vision infrared detection - not sure if it is literally FLIR based or not, but I figure I could use this feature in addition to whatever my landing lights  do to provide me with as much situational awareness that I need during a landing approach or takeoff at night.

I then did some research on VAF regarding the installation location of the heated pitot tube controller. Some folks are mounting this on the rib just outboard of the last inspection/service palte location on the bottom of the wing, while others are installing it in the end rib or even on an inpsection plate itself. I will most likely put mine out on the end rib for ease of inspection and service, but may also explore the inspection cover installation a bit more. I am less interested in the rib location because I think this location is difficult to both inspect and service if/when the time comes. Others even run it all the way back to the fuselage.

The pitot tube mounting location is yet another decision that has to be made. I will mount it in the next bay outboard of the bay where the aileron belcrank is located. There are two reasons for this:
1. Dynon has some rather long 3/8 inch air line tubes coming out of the pitot tube where the air lines willbe connected and run back to the avionics, and this will provide enough room for them to be bent  and connected to the lines
2. It allows for connection of the air lines so that they can run through a mounting bracket underneath the entire aileron belcrank assembly, with no chance of interference with the bellcrank or the push/pull tubes. This is something that is rather important, if ya know what I mean.

Also need to get up in the rafters and shelves in the garage and start pulling down the aileron, flap, and wing skins - wow - I will have to order the fuselage kit or something to keep those shelves fully utilized!

Hope to have some pics tomorrow.