Tag Archives: home-built aircraft

Aviation

Another GREAT shop day

Two great shop days in a row, how awesome is that?

Another five hours today; that makes ten hours for the weekend. A fantastic way to wrap things up for the week, I think.

I started out the day by sanding the stern post core and preparing it for bonding the ⅛” skins to it. The T-88 did a great job bonding the edges of the core pieces together, and waxed paper works fantastic as a barrier and release paper. I hadn’t worked with T-88 before so this was a trial run for me. T-88 measures out and mixes up easily. The change from two components, clear and honey, mixing to a cream color when stirred together makes it really easy to tell when it is thoroughly mixed. The best part is the smell, or lack there of. I have been doing some work with polyester resins in my day job, and that stuff is really noxious. The T-88 is so easy to work with and so far I am really happy with its performance.

With the stern post core bonding to the skins and clamped up, it was time to move on to the firewall. First I had to remove the strengtheners from the original firewall which took a little longer than I had hoped for. Once all of the hardware was removed and the strengtheners separated it was time to mark out the new firewall. After marking out the cut lines I set up the table saw and did the rip and cross cut for the basic shape. The new firewall matched up perfectly with the old one.

I decided to clamp them together and used the old firewall as a drilling jig for the new firewall which worked out very well. The holes are really snug on the bolts so any misalignment would make life difficult at this point. Fortunately everything lined up spot on and bolted up cleanly. The counter-sink worked much better this time around. With everything torqued up, the bolt heads are just a couple of thousandths below the surface and they look great.

   

   

With the shape cut and the strengtheners attached I started setting up some test boards for the bevels. Both side edges of the firewall have an 8.5º bevel and the top has a 5º bevel. I was concerned about the set up and I wanted to make sure I didn’t hose the second firewall. After a few sample passes through the table saw I had the angle and distance from the fence set up just right. Time for the bevel cuts.

   

After the bevels where cut it was time to cut the parallel notches in the bottom for the firewall that will eventually accommodate the longerons. There are still several things to do on the firewall but it is well under way.

   

If next weekend comes even remotely close to this weekend in productivity I should be able to finish the firewall and maybe even get a good head start on the stern post, at least get the rough blank cut for the stern post. Looks like I need to get my ducks in a row as far as materials go for the spar bulkheads.

Until next time, blue skies and tail winds.
~FlyBoyJon

Aviation, Ramblings, School

10 days since my last confession

Ack! I had hoped to get something posted by now. Well here we go, this post will cover a lot of ground, aviation and otherwise.

In the other category… A lot of stuff has been going in my world over the last few years. I started an AS in Aviation Operations degree program at Mountain State University in 2006. With my aviation experience credit and classes completed, I have 50 units out of 60 for my degree. Before I could finish the program my mother passed away. I had to drop out in the middle of the semester so my grades took a nose drive. All of my aviation credits are pass/no pass so thy don’t affect my GPA. My Presidents List earning 4.0 was now a pathetic 1.8. To keep my financial aid I need to maintain a minimum of 2.0 which presents a problem for me.

To get my GPA back in order I decided to go to San Jose City College and take some classes. I made this decision a while ago but recently I had a bit of an epiphany. It became clear that I needed to do more than I had planed back in 2006. I decided to pursue an Aeronautical Engineering Degree which means I need to cover all of my GEs. Very few units at MSU are transferable to San Jose State so I need to fulfill them at SJCC, hence a complete over-haul of my education plan. I still want to finish my AS at MSU, but that will have to be part time while I work on my AA at SJCC. I’m guessing you can see why I have been busy. I start classes again on Monday.

Now for some of that airplane stuff. Today I worked on the firewall bulkhead and the stern post. I started by marking out everything I wanted to cut. The Doug Fir I am using for the core of the stern post was laid out on a piece of 1″ x 6″ board and the skins for the stern post were laid out on a piece ⅛” ply. With the wood for the stern post cut out I turned my attention to the firewall bulkhead.

   

The work operations for the firewall bulkhead included cutting out the block shape and drilling the holes to attach the stiffeners. Once the stiffeners are in place the beveled edges on the sides and top can be cut as well the curves in the upper corners and drilling all of the holes. I cut the rough shape and drilled the stiffeners. Then I bolted it all up.

   

The aft side of the bulkhead looks good, the forward side however, didn’t come out the way I was hoping it would. The countersinks are a little too deep, so the screw heads that are supposed to be flush are a bit deeper that they should be. The only solution for this predicament is to cut out a new firewall. While I’m not happy about it, I would rather hold myself to a higher standard than let something slide.

I didn’t feel like pulling out the table saw again so I decided to wait until tomorrow to redo the firewall. I still had some time to keep working so I bonded the Doug Fir lumber for the stern post core. Another to-do for tomorrow will be to bond the skins to the core.

   

Since I don’t have any bar-clamps *hint, hint* I had to come up with another solution to keeping the wood firmly in place. This is where my improvised cord clamp comes it. It is just some nylon cord with the ends tied together. Take a piece of scrap wood, put in between the work piece and the cord and start twisting. Simple but effective. The T-88 structural adhesive does not need a lot of pressure to hold the joint together, in fact you need to be sure not to apply too much pressure or the adhesive will squeeze out of the joint, so the cord clamp works well.

That wraps it up for today. Tomorrow is another day in the shop so we’ll see how much gets done.

Until next time, blue skies and tail winds,
~FlyBoyJon

Aviation

Airfoils

Airfoil RibsThe last few days have been a bit of a blur. I am shaking off the last remnants of a frustrating head cold that lingered for way too long. This week was also the first week of an early class at SJCC before my spring semester classes begin on the 31st. With the cold and classes I haven’t gotten much of anything done at the day job and getting into the workshop was near impossible.

As a consolation, I managed to get in a bunch of pseudo-shop time in by working on the airfoil templates. All totaled up I put in 11 hours marking up the templates on contractor’s paper and cutting out the finished templates. It is surprising how much time can be spent on laying out even the smallest airfoil. Over 30 measurements are used to lay out the basic shape, and you still have to round everything out for a smooth form. Science and art in one operation.

The picture above shows all seven of the airfoils laid out on the kitchen floor. On top is the wing with its 58″ chord. Below the wing is the stabilator, and below the stabilator are the five airfoils that are stacked to form the rudder. There will be 30 copies of the wing rib, 8 of the stabilator and only on each of the rudder ribs. There are a total of five variations of wing rib and two variations for the stabilator, but they are all based of the basic forms. I will post more about the jig and duplication process when I get back to the airfoils. For now, since I am feeling much better, I move back to the bulkhead construction portion of the project.

This last week’s diversion to the airfoils is a good example of building flexibility into your project schedule so you are able to take advantage of available time when life strikes.

Until next time, blue skies and tail winds.
~FlyBoyJon

Aviation

Day 5 or What I Learned About Building Airplanes

Time Card As you might have already guessed, I try to be very organized. Because one of my goals that goes along with building the VP-1 is to get my A&P Certificate, and some of the logged time can be applied towards said certificate, I decided to try and keep very accurate records of time spent on the project, both shop time and administrative time. To that end I picked up a box of time cards. In theory 100 double sided time cards should last 3.8 years.

Why keep time cards? Not only is it a great way of keeping track of how much time I spend on the project but there’s more. For one, it’s a physical record just for tracking time. Sure, the builders log will do that too, along with a bunch of other information, but I think handing over a stack of time cards to an FAA inspector as proof of work as a separate record shows attention to detailed record keeping that is a very important part of an A&P’s job. Also it is an easy record to have signed by an A&P I am doing work with as supervised work.

There is another reason to use time cards. The idea is to have a slot for every day of the year, a new time card every week, staring me in the face ether say “Wow! you worked a lot on the airplane this week” or “Dude! A whole time card and no work on the airplane?“. It is its own incentive to get out to the shop every day or so. If I get hung up waiting for parts to work with, I am still logging admin time, so there is no reason not to do at least something; at least thats the idea behind it.

This first five days I have logged some time and learned a few things. As promised, I started working on Saturday January 1st, 2011. I started by laying out the Doug fir braces for the firewall bulkhead, relatively straight forward, tolerances were tight with the blade kerf and all, but it looked doable. Then I moved on to laying out the firewall itself. Over all I spent two and a half hours laying out everything and measuring everything several times. After that, I called it a day. I have heard so many builders say “Don’t rush things, you’ll only have to do it over.”

Firewall Bulkhead LayoutSunday morning, really early, like 2am early, I woke up with a thought, the layout for the bulkhead was wrong. All of the measurements are referenced from one of two places, ether from the centerline/bottom, or from the outside edges. Here in lies the problem, The centerline marks are fine as long as the centerline doesn’t move. The edges however are in-fact going to move due to a beveled edge that trims off a half inch on ether side. So I can ether go back and remark all cuts referenced by the half inch, or, and I think this best, cut the rough, bolt on the Doug fir as is needed before beveling, then recheck the centerline, and only then move in on the edge cuts. It is a lesson in processes. With nothing but schematics and no real guide for process, you have to take a little extra time to think it all the way through.

Another thing I learned was during my shop time on Monday. I only put in an hour, mainly due to disgust with myself. Don’t cut wood with a wrong or bad blade! After all these years of doing workshop type stuff this should be a second nature no brainer. Well, I was a no brainer apparently. I burned up some perfectly good Doug fir and made myself some push sticks for my next time in the shop.

Then Wednesday came. Shop time, two hours. Yup, changed out that blade and made some real nice soft fluffy sawdust. A beautiful sight and smell, much better than the cloud of burning lumber from Monday. Both of the braces came out nice and neat, square and level, and needed only a nice basic sanding to clean off the light saw marks. This really makes up for Monday.

push sticks   Firewall bulkhead braces

Last weeks time card only had two days from the new year. This week is only half over and I have two days with shop time! I am hoping to get the firewall roughed out by the end of the week. Wee shall see if the day-job will accommodate.

Until next time, blue skies and tail winds,
~FlyBoyJon

Aviation

Firewall Bulkhead

Firewall BulkheadGreetings all you aviation types out there!

After much debate, a few false starts, and some gnashing of teeth, I am actually starting to build the real full-scale VP-2. I was looking for the least expensive assembly to get the ball rolling and decided to start with the bulkheads. The firewall bulkhead seemed like as good a place as any to start. There are a some good reasons to start here too, first off it is frequently station 0 for all of the location references and weight and balance data. The firewall is also the forward most airframe structure, and this assembly doesn’t require any “aircraft grade” lumber in its construction.

There are of course other aircraft grade materials needed for the assembly, but they are relatively inexpensive. In this case it is 10 bolts with corresponding nuts and washers. I ordered the bolts, nuts, and washers from Aircraft Spruce on the 29th, and I already have the doug fir. All I need to do is pick up “a good sound piece of (3/4“) D.F. exterior ply”.

With hardware en-route (I expect it this afternoon!), board lumber in hand, and plywood a short drive and a few bucks away, I started studying the fine details of the firewall bulkhead assembly. I have been going over the plans for the bulkhead with a fine-tooth comb looking at every minute detail, arc, and dimension. This bulkhead is solid unlike the forward and aft spar bulkheads or the stern post. The other bulkheads all have doug fir and white pine cores with aviation plywood (1/4” and/or 1/8“) webs. The firewall is a slab of ply with doug fir reinforcing members bolted on the aft starboard and port sides.

A challenge presented itself with the hardware specifications. The bolts were spec’d on the plans, but the washer and nut were not. With a little detective work I found a vague reference in the “General Assembly Procedure” text in the back of the plans set. The only references to the firewall bulkhead don’t say anything about what hardware is going to be used. There is a brief note that lists a few pieces of hardware but it has no references to assemblies so you are left to your own devices to figure it out. I found the reference after looking up hardware in the Aircraft Spruce catalog and figuring it out there. There needs to be an updated, cohesive plans set for newbies without aeronautical engineering degrees. After I take an AutoCAD class or two I think I’ll get on that.

On several occasions I have heard that when building an airplane on your own you should try not to look at the Big Picture too often. Taking the construction one assembly at a time and looking at the Big Picture only when between assemblies to decide what to do next and for interconnectivity issues. I have been scouring over the whole plans book in detail for a while now and I am starting to see the whole as a collection of smaller independent projects.

I can see now why a lot of builders that jump in feet first without a lot of thoughtful review find themselves feeling in over their heads after a while. I can also see how experienced builders can switch from one area of the aircraft to another or have a couple of completely unrelated assemblies going at the same time. It seems that the secret to keeping a project going and making regular and significant progress is that ability to compartmentalize the structure and focus only on the areas that are currently in progress and always have something to work on. Keeping build time for focused building and planning time for the strategic organizing and advance ordering of materials that may take a while to arrive. The whole process is really three distinct jobs. The Project Manager, the Materials Procurement Specialist, and the Builder/Mechanic. For a project to be efficient and run like a well oiled machine a builder has to keep all of those jobs going independently and up to date while keeping it all synchronized.

As the project manager I have been reading the AMT handbooks and scouring the internet for various upgrades/mods for the VP-1/2. Yesterday I found some drawings from builders for things like landing gear mods, break systems, various trim devices, canopies, fairings, and more.

As the Materials Procurement Specialist I think it’s time to head out an buy a piece of 3/4” plywood, that is if I want the Builder/Mechanic to have something to do tomorrow.

Until next time, blue skies and tailwinds!

~FlyBoyJon

ETA: The delivery came from Aircraft Spruce while I was out picking up the plywood so everything is in place for a sawdust party tomorrow.

Aviation, Projects

Something about lumber

We Can Do ItIv’e spent some time sourcing materials the last two months and I found out a few things; the most important of which is that it is good to look for local suppliers of wood products. Having said that, I am going to be buying my lumber from Aircraft Spruce. “What the what?” you may be thinking, well here’s the thing, I have been poking around for spruce and doug fir as well as marine plywood. The 1/16″ plywood is a flat out no-go any where else locally. The 1/4″ and 1/8″ plywood can be found locally but the quality varies widely as does the price. I thought I had a supplier for a really low price, turns out the quality matched the price.

I had much better results in the Lumber search in that I could find good quality doug fir. The price for it matched or in some cases exceeded the cost of spruce, which I could not find locally, at least not in quantity or quality. So I am back to Aircraft Spruce, not that this is a bad thing mind you. The main reason I was looking to buy locally is I try to do that with everything. Buying locally improves the local economy, and buying from small business helps revitalize the vanishing middle class. At least I can say in this case that I will be buying regionally from a small/mid-sized company. Aircraft Spruce has a store down in southern California, it’s a seven plus hour drive from San Jose, but paying for gas is considerably cheaper than the freight costs having it shipped up to me. I plan on buying stock sizes and milling myself to keep the costs down and ensure ready availability.

Now that I am back to were I was last month as far as the materials quest goes, I am more prepared and knowledgeable in the area of aircraft lumber. I know what I can get and where to get it, as well as what substitutions I can make for specific applications. It looks like the plywood is going to come in just shy of $1,000 (materials and tax). I need to calculate the lumber requirements, that is this weeks project, but I am estimating that to be about $500. I will need a few odds and ends to have on hand, basic airframe materials, so I am planning on a $2,000 trip including the round trip fuel for the van and me. It’ll be a long day but a fun one I am sure.

The only tool I need to look into at this stage is a plainer which I am sure I can find at Harbor Freight in Newark. I also need to make a router table top and several jigs for cutting precisely duplicated wing ribs, all of the materials for this stuff I ether have or can find locally on the cheap. All-in-all I think I am getting really close to making a lot of saw dust.

Until next time, blue skies and tailwinds,
~FlyBoyJon

Aviation, Projects

Keep moving forward!

As you may have guessed, the day job got in the way of my preferred interests making it hard to get anything done on the airplane. But, now I’m back in the shop going over the construction plans trying to decide where to begin. Most builders seemed to start with the empennage. Building the vertical stabilizer and the horizontal stabilizer first. Because of my shop’s space limitations, I’m thinking about starting with the bulkheads; building the firewall bulkhead, forward spar bulkhead, aft spar bulkhead, and lastly the stern post.

VP-2After the bulkheads are built I can do a temporary fit of the cabin, building the seat components and cabin floor structure without permanently affixing them to short, temporary longerons. I can’t build the completed fuselage just yet, there is just nowhere to put it. Next I can move on to wing ribs, horizontal stabilator ribs, and vertical stabilizer ribs. With all of the ribs cut I can go ahead and start building larger assemblies. I should have enough room to easily store the completed vertical stabilizer. Then I can move on to the horizontal stabilator spar and the stabilator itself.

With the empennage components completed I can move on to other assemblies, forwards spars, aft spars, fuel tank, control stick, landing gear and such. By the time I get to this point, I should have access to a larger space for fuselage construction then I can put it all together. At least that is the plan for now.

As I’m sure you figured out by now, because of my space limitations I am looking to build flat components first, then flat and/or small assemblies. This should keep my space requirements to a minimum until absolutely necessary for the fuselage. The longer I can keep the build in a small space the better.

On another subject, I have been reconsidering the model this last week. The paper laminates that I planned on using as plywood substitutes for the 1:4 scale model just don’t provide enough structural support or hold shape well enough for me to consider them viable, especially the two-ply and four-ply laminates. I had thought about purchasing some balsa materials in the proper size but I almost fell over when I saw how expensive balsa wood has gotten. Another problem is the mechanics of milling small pieces of material from Douglas fir. That being said, I have decided to go with the VP-2 rather than the VP-1 and build it as a single place instead of a two-seater. Because I don’t need to compare the airframes, I don’t really need to do the model. If I run into a problem I can always model the assemblies involved if I need a solid reference.

Following the plan outlined above and building the bulkheads first all I should need to put together right now is a materials list for the bulkheads, source it out and figure what my cost are going to be. I already have some of the Douglas fir and I know where to get everything else I need, so this should be little more than an academic exercise, until I start making saw dust anyway. Oooo… sawdust… I am really looking forward to building.

Until next time, blue skies and tailwinds.
~Jon

Aviation, Projects

Back on track

Greetings Intrepid Aviators,

The last few days have been plagued with zombies; no seriously, take a look . Now that the zombie menace has been put down for the year, they will be back next year, it’s time to get back on track with the matter at hand, building an airplane.

Nothing new has been done on the 1:4 scale since last week, but I have had some thoughts on the matter. I think making the paper laminates in smaller sections rather than the 24” x 12” pieces I planned on, using thinned glue, and pressing the material with more weight should help make the resulting material a high quality substitute for very thin plywood. This week I am going to focus on the laminate first and then if all is going well I will get started milling the lumber materials from the Dough Fur I purchased last week.

VP-2Another task for this, and the next few weeks is to dive into the plans in much more detail. I have looked over both the VP-1 and VP-2 plans but I have not really focused on them in detail or thought about what assemblies to begin with. I am considering picking up a large drawing pad and redrawing the plans so that all of the details for a sub assembly will be presented on a single sheet. I like to study the details of drawings and plans by reproducing them by hand. The process helps create 3D models of each piece and assembly and how they interrelate with other parts. It gives me a clearer vision of the entire plane and all of its component parts. By redrawing the plans I will also be able to come up with a complete parts list, assembly parts lists, work operations list by assemblies, and other useful administrative minutia that should make the build go smoothly for me. A side benefit is taking the time to include the 1:4 scale dimensions in parenthesis alongside the full scale dimensions.

All of this may sound like it is complete over-kill, and it may be, but it’s how I work. I like to plot out all of the details and have contingencies for problematic areas. It comes from decades of working with non-profit groups and producing events. Even though I have been harassed mercilessly for taking so much time in planning to the smallest detail, everything works out smoothly even in the face of adversities most of the time. It is an attitude thing, too. When running an event, it is easy for panic and frustration to kick in when something starts to turn south, particularly during the event. It’s all about focusing on solving the problem at hand, removing the cause, and smoothing out the bumps. Oh, and doing it all behind the scenes without the general public knowing it happened at all. All in a day’s work as they say.

Blue skies and tailwinds,
~Jon

Aviation

Starting the 1:4

1:4 MaterialsWell, to start things off this post is a bit late. As I mentioned in a previous post, this time of year is very busy for my wife and I. I did manage to get out and pick up some supplies. A trip to Home Depot yielded some Gorilla Glue for the frame and some Titebond III to make the laminate that I will use as a plywood substitute and thinned a little it should work well as a sealer to replace varnish on the 1:4.

After looking over the wood at HD and finding all of their lumber riddled with knots, I decided to head over to Southern Lumber. Since I was planning to use clear vertical grain Douglas fir for the aircraft build I decided to use DF for the 1:4 as well. I have heard that DF is more difficult to work with so it makes sense to experiment a little with it before buying a bunch for the full size aircraft.

WorkspaceAfter I got home I set up a little workspace at my desk and set up an area for testing the ply material layup. I cleared the space and prepared the surface, laying out some 6 mil sheeting and taping it down to the desk top. After the work surface was ready I started the first piece of the paper laminate by covering a 1′ x 2′ sheet with Titebond III. Once the glue was brushed over the entire sheet I let it set until slightly tacky to the touch, once it was ready I added the second sheet and smoothed it out, making sure any air bubbles had been worked out, you can see these steps in the pictures below.

Later in the day I checked out how things looked. I was not pleased with the results.

let it dry under a little weightmake sure glue is spread out evenly spread the glueAfter all was said and done, the end product was wrinkled, warped and in general undesirable. Thinking back to my days doing some bookbinding I remembered that glued paper products need considerable compression and dry time. I am going to experiment a little more with the laminating process. I still have hope for the it working well as a stand-in for plywood.

Next week I should have time to start the milling. I know what size pieces are included in the spruce kit so I can start with those. Once I have the lumber milled I can get started with the bulkheads. Hopefully I will have figured out the ply stock issue by then.

Till next time, blue skies and tailwinds,
~Jon

Aviation, Projects

Materials

Got out this morning and did another material sourcing run. It didn’t go as well as I had hopped, but that’s okay. I have made some solid decisions on materials and can now start buying what I need for the 1:4 scale project, as well as buying materials for the full scale airplane. Full steam ahead!

Full Scale

First and foremost, I’ve been able to source a majority of wood products locally. However, it looks as though I will have to run with one of the regular aviation suppliers for the 1/16″ plywood. I can find 1/4″ and 1/8″ but that’s as thin as local suppliers carry. 1/4″ AA marine is relatively easy to find, 1/8″ is tougher, 1/16″ is nearly impossible in any grade.

I found a local source for aircraft cables of the mechanical control variety; not electrical, which I suppose would be obvious to anyone who has been reading this blog since I don’t plan on installing an electrical system in the airplane. It looks like Orchard Supply carries aircraft cable as a regular item.

A local supplier for composite materials is TAP Plastics. I had a feeling it wouldn’t be particularly difficult getting some of the composite supplies locally. They don’t have all of the right fabrics, but they do have some. I am not sure about the resin and epoxy they stock, but for the basic materials to work with them, well those they have in spades. I will check out the chemical stuff later when I get to a point that I actually need to think about composites.

1:4 scale

I am rapidly coming to the conclusion that I will need to manufacture the ply products I need. The lumber is readily available, ply products on the other hand… With the full scale ply sizes being 1/4″, 1/8″, and 1/16″ the 1:4 sizes are 1/16″, 1/32″, and 1/64″ respectively. As I said earlier in this post, it is tough if not impossible to find ply this thin anywhere locally. So, I have resigned myself to the arduous task of manufacturing a replacement material.

At this point I think it will be a laminated paper product. Layers of a a heavy water-color paper should do nicely, maybe a 25 sheet pad. With any luck the end product will be moderately stiff ply-board in the appropriate thicknesses. In 1:4 scale a 4’x8′ sheet of plywood is only 1’x2′ so it shouldn’t be difficult to find the paper stock large enough. I was thinking of using Gorilla Glue as the laminating adhesive mainly because it is very strong and you can use water to thin it for spreading a very thin layer evenly across the surfaces of the laminates. I was hoping to avoid this but ya gotta do, what ya gotta do.

Composites

In truth the only composite parts that I would need to build are the engine cowling and the turtle-deck faring which isn’t even a required part, though, I must admit, I am definitely warming up to the idea.

The EAA Chapter 62 meeting I mentioned in the last post got me thinking about composite materials and processes. I haven’t done any fiberglass work in a long time but that is going to change with a day-job project that I recently started. It has some fiberglass work that needs to be done, so I figured I could brush up on those skills and maybe put some of the new techniques into action.

I purchased a book on fiberglass repair and construction to refresh the old gray matter on the subject. It has nothing to do with aviation but it is all about the basic skills for fabrication and repair in the medium. The book was published in 1988 so some things might be a little different or out of date material-wise, but the skills should transfer reasonably well.

Till next time, blue skies and tail winds,
~FlyBoyJon