Tag Archives: Pocket Change Builder

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

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

N49FB

This week has been a little hectic and next week will without a doubt be tougher. Every year there is a world wide event the Saturday before Halloween called Thrill The World, my wife and I organize the San Jose / Silicon Valley event. As you can imagine with the event coming up on October 23rd we are rather busy getting stuff ready. Our group Grave Mistake has only a couple more dance workshops before Thrill Day. This makes for a crazy day-job schedule to go along with the fun-stuff, and that doesn’t include the aircraft project! While I will be trying to get at least a little done, buying some materials at least, doing some milling at most, this week and next are a bit tight on time.

VP tailI do have something cool to report though. You may remember on September 21st I filed for an N-number with the FAA through there online system. For those that may not know what I am talking about; the N-number is an aircrafts identification number, it is also referred to as the tail number. They said it would take up to three weeks to get the confirmation letter. I put October 13th on my calendar as a follow-up date to check back with the FAA if I had not received my confirmation letter. Being excited about the project, I checked back every so often to see if the FAA had processed my request. The website says that they update the reserved N-number database weekly, so that’s about how often I checked back. The number I submitted kept coming back as available. Until… the 12th of October! I still have not received the written confirmation but the number shows up in the database as being reserved for ME! WOOT!

As you might have guessed by the title of this post and the little addition to the header graphic, oh, and the giant VP tail to the right, my N-number for this project is N49FB Fox-trot Bravo of course for Fly Boy. If I could have gotten Fox-trot Bravo Juliet I would have, but that does not fit in the numbering convention used by the FAA so Fox Bravo it is. I just like the way the short number sounds… niner fox bravo… if just sounds cool to me. Okay, I’m getting a little too AvGeeky even for me now.

On a builders note; I mentioned in the last post about doing some work with composites on my day-job. That is progressing and I have been reading up on the process as time permits. The more I think about it the more I think I will do the cowling myself. I am still not sure about doing the turtle deck. I have seen a number of VP-1 and VP-2 examples with and without the dome called for in the plans. That is way down the line, so I’m not going to burn a whole lot of cycles on it just yet. I also need to see how fast I can re-acquire my old rusty fiberglass skills.

Thats it for now.

Blue skies and tailwinds,
~Jon

Aviation, Projects

Aircraft Grade

Greetings Aeronauts,

This week has been interesting. In Monday’s post I talked about getting a copy of the VP-2 plans and the idea of building both the VP-1 and the VP-2 in 1:4 scale to compare the plans. Looks like I will begin working on an airframe sometime next week. I am really looking forward to start actually building. This weekend is jammed with Grave Mistake workshops and the Step Out: Walk to fight diabetes 5k that my wife and I participate in every year along with some friends.

Throughout the week I have been interacting with the great people in the Volksplane Yahoo Group and the fine folks at Oshkosh 365. I got several replies when I asked for some advice on adhesives for wood aircraft. The plans call for Aerolite which does not appear to be readily available. For the most part I got a lot of thumbs up for T-88. Other suggestions included, Aerodux which is a Resorcinol Formaldehyde Adhesive like Cascophen, and West System Epoxy. I am not sure which one I will go with but I am leaning toward the T-88. I need to get the MSDS for each of them as well as take a look at volume, weight, coverage, and relative strength comparisons, and yes, the cost comparison, too.

Another question I had was about Certified Aircraft Grade Lumber. It looks like there ain’t no such animal. In short, your aircraft lumber supplier checks the material to make sure it meets the standards of Aircraft Grade, those standards being MIL-S-6073 Military Specification, Spruce, Aircraft, MIL-P-6070B Military Specification, Plywood and Veneer Aircraft Flat Panel, ANC-18 Design of Wood Aircraft Structures, and of course the standards set in AC-43.13 1B Maintenance & 2B Alterations Aircraft Inspection, Repair & Alterations. They inspect the material, stamp it, and price it accordingly. It is not a federally recognized certification, it is a voluntary compliance to Military Specifications set back when the military used wood aircraft, with a little updating now and then. Don’t take that to mean that I think it’s all hokum; I don’t. The standards are there because they are appropriate to the application. If you are not sure how to grade lumber or are not sure if you can determine compliance reliably, buy lumber from someone who can make those assurances!

While Sitka Spruce is the de facto aircraft lumber, it is not the only species used. The main factor in choosing wood other than structural strength is grain, vertical grain (VG) to be precise. A VG Clear Douglas Fir (DF) is one of the closest quality woods to Sitka Spruce, in fact it is stronger than the spruce in most respects. The drawback with DF is its weight; DF runs about 26% higher in weight than Sitka. In this aircraft, a majority of the structural weight is in the plywood and not the lumber, so the impact on gross weight using DF instead if Sitka should not be that much. Without an electrical system, using minimal instruments, and other weight saving details like single occupant controls, I think the trade-off in favor of structural strength is reasonable, even wise, not to mention that as a Pocket-Change Builder I can’t overlook the cost of DF being significantly lower than Sitka. Having a supplier less than 20 minutes away doesn’t hurt.

Most likely I will end up going with the VP-2 airframe. It is intended for a higher gross weight and a higher useful weight. With two occupants taking up 170 pounds each, that gives me 340 pounds to work with as a single pilot. While I won’t need all of that, I sure as heck am not under 200, nor have I been since 6th grade. I wrestled in the 220 class in Jr High. The extra airframe strength and the VP-2 load capacity provide a significant safety margin over the VP-1 design which is why I am leaning in that direction.

Something fun thing to add to this week was my first EAA Chapter meeting. There are two chapters here in San Jose with a couple of others less than an hour away giving me a lot to chose from as far as finding a good fit. Thursday night was Chapter 62’s monthly meeting. I am not sure if I am going to join 62 yet, but I did have a good time there. The chapter is more of a flying and activities chapter than a building chapter. As it turned out, last night was a great night for me to go to a meeting there because the speaker was Zeke Smith, author of Advanced Composite Techniques.

Zeke demonstrated his process for vacuum forming a leading edge to be used on an an ultralite project. The end product has a thin outer skin and foam strengthening with plenty of room for similarly light ribs. I was amazed at the strength of the leading edge without any support and the incredibly light weight. If I was working on a composite project I would be buying this book right now. I may still get it for this project to use his techniques to form the engine cowling and turtle deck of the VP. That might even give me more weight advantage for the DF…

Only slightly off topic, I can easily see myself building a composite VP-2. In fact I can see some of the layups for Zeke’s vacuum process in my head now. To quote Red Leader Stay on target.

For anyone interested in helping out the FlyBoy, I need to get a print copy of AC-43.13 1B/2B. Contributions to the Pocket-Change Builder’s Fund are always greatly appreciated.

Until next time, blue skies and tailwinds,
~FlyBoyJon

Aviation

VP-1 or VP-2?

Decisions decisions… I purchased the VP-1 plans set last week and acquired a set of VP-2 plans this weekend, now I have to make a decision between the designs. Which one should I build? I am estimating the VP-2 would cost between 5% and 7% more for the materials. I don’t think there would be much of a difference in the build time. The gross-weight bump and the extra seat are certainly good reasons to lean in the direction of the VP-2, but ultimately the decision needs to be a combination of practicality, mission, and my own comprehension of the plans. If one set of plans proves to be significantly more difficult than the other for some reason, that will affect the decision as well.

Evans Volksplane VP-1The idea of building a scale model before starting construction of the full scale plane had come up in a previous post. Now it looks like that might be the best way to decide between the two designs. If I build both of the aircraft as scale models first, that should give me a better parts list and I could evaluate the difference in material costs more accurately. It will also give me more insight in the build process for both airplanes.

Cost estimates for a 1:4 scale model of the VP-1 came out to about $45. Building two 1:4 scale models should come in less that $60. A question more important than cost is 1:4 or 1:8 scale. The 1:8 scale becomes problematic as the smaller plywood sizes in that scale would have to be balsa wood, which would increase the cost significantly, or be laminated paper stock, adding a lot of time in material fabrication. The idea with doing the models is to decrease the overall time and address problems with fabrication, not create materials and a whole new set of issues. Another problem with the 1:8 scale is hardware. In 1:4 scale I shouldn’t have a problem locating scale hardware.

Evans Volksplane VP-2With 1:4 scale the only real problem is that the product is on the large side. For the VP-1 we are talking about a 6′ wingspan, 4’6″ long, and a 1’3″ wide tail. The tail being the widest part of the structure with the wings detached. The VP-2 has a 6’9″ wingspan, is 4’9¾” long, with a 2′ wide tail. These are some big model airplanes and the only thing they are missing is the engine and maybe the rigging.

In the end I know that building the scale models is going to help save me a lot of time in the long run. I also know that the 1:4 scale makes more sense for dealing with potential build problems. With the models I don’t have to worry about Aircraft Grade materials and I can devote my time to building rather than sourcing. I also think that the models will give me a better estimate of the build process, and allow me to modify my build order and schedule.

It’s hard to say what direction things will take. I have my own ideas about the build process, when things will happen, how they will happen and all of that. No matter how much I plan, since I haven’t done this before, I just don’t know the path things will take.

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