As the summer draws to a close and the kids head back to school next week, I'm getting prepared to get moving in the shop on my build.
I'm hoping to finish up the 701 wing repair and make the updates necessary to the other wing. This will free up some bench space for tracing out my parts on the the aluminum sheet.
I got the wing spar tip extensions made and bent this week and added the stiffener angles:
All ready to be fit and installed, leaving just he skins and extra ribs.
I used some of the spare space on the bench to pin and tape my wing form templates together:
After tracing this out on the plywood, I got to work rough cutting out each of the form templates. These will become the final forming blocks once I final cut and sand them to proper size. I think I have most of them cut out with the exception of a few that I need to find from the 701 which may match (why make them if Ron already has them made?):
We are heading south in the next couple of days to catch the Brantford Community Airshow (see www.communitycharityairshow.com for details). Bonus news.... aircraft building supply store Aircraft Spruce is co-located at the same airport and I'm planning a little shopping :)
Next up, laying out some part templates on aluminum sheet and finish sizing the forming blocks.
LETS BEND SOME METAL!!
A while back I saw the following quote which really sums up building a big and sometimes overwhelming project like an airplane is....
How do you eat an elephant?
I have a lot of time on nightshifts at work to study my 750 plans and as I think of all the things I need to make, decisions on features I think I want to incorporate and how I'm going to make all these the parts, I get a bit discouraged. It is indeed a massive undertaking.
But as I keep being reminded both by others and myself, it's all the small bites that add up.
I find myself spending more time focused on completing tasks than taking pictures of my build which is both good and bad. I'm probably getting more done this way, but it doesn't leave a lot to add to my blog for you readers. Most of what I've done in the last couple of weeks is really just repetitive steps that I've already shared. But here is some of what's been happening.
In my last post I said I was headed back to the "drawing board". Here is the correct plywood I should have been using for my form blocks. Much smoother and knot free!
Each form template gets traced twice in opposite (flipped over), creating left and right side forms. These will be cut out in rought form using a hand jigsaw then cut close to final size using the scroll saw (more on this later).
Ron and I continues on our discussion regarding the wing extensions for the 701 wings I'm helping repair. Now that the main repairs at the root end are done, I can focus on this. Ron wants a 18 inch extension, so that's what I'll work towards.
First we have to remove the "factory" wing spar tip extension. I say "factory" because like a good majority of other "factory" items on this plane, it's really not to "factory" plans. Not the right thickness and missing two critical rivets at the upper and lower spar caps.... sigh. At least this time it's coming off to be replaced with longer ones, not just coming off to be fixed or replaced as original.
The wing spar tip extension isn't considered structural per se, but it is an important component of the wing. It supports the fiberglass wing tip and completes the outer structure end of the wing. Here it is close to it's original position on the end of the spar (I had already removed it at this point but forgot to take a picture):
....and removed from the spar. There appears to be a small wrinkle in the wing skin behind the joint, but that can be fixed easily and will be underneath the new skin extension:
Next we had to decide on how to handle the new wing skins extensions and how they would attach to the old skins. We believe at this point we can get away with a simple overlap with a double row of rivets, but we'll probably add a doubler strip underneath for strength, or even another wing rib. We trimmed the lower and upper wing skins to a convenient length and made sure to leave enough skin outside the last full wing rib. Where the trim line ended up (defined by green frog tape below) is actually a good place for a new rib:
The upper wing skins were trimmed back in the same fashion. Then, using the original plan dimensions I cut a new wing spar tip extension web (actually two, one for the other wing to match), by adding a full 18 inches to the inboard end. I was very important to get these right as they need to be perfectly straight to match the wing spar. After careful measuring, they turned out perfectly! This was also good practice making the long scoring cuts from a full 4 x 12 foo sheet of 0.025 aluminum. I'll be doing the same for my 750 wing spars and tips too:
With a little thinking and practice on a scrap piece of matching 0.025 aluminum, the top and bottom flanges were bent to a perfect 18mm width, leaving the total top to bottom dimension of 209mm, exactly as the plans call for!
We are going to wait on putting in the lightening holes until we see where the new ribs end up. The flapperons will also need to the extended, making another pick up point necessary which in turn will determine where one of the new ribs goes.
Ron keeps reminding me to continue working on my stuff too. So I took some time to make some of the smaller parts needed from some of the "scraps" left over from the 701 wig repair.
It's paying off studying the 750 plans when I can too. For example, I new I had to create 6 full length flapperon ribs and probably had enough cut-offs lying around from the repair I was doing to complete them. But then I recalled that the plans call for 4 full flapperon ribs made in 0.016 thickness and 2 full flapperon ribs in 0.025. I referred back to the plans and remembered that the two thicker ribs are "root ribs" meaning they are where the control rods for the flap actuators attach, requiring something more robust. The other 4 thinner ones are distributed elsewhere in the flapperon assembly. Glad I noticed nd didn't make them all the same!
They use the same templates, so I traced out the other four flapperon ribs on the 0.016 aluminum:
Although almost any thickness of aluminum can be roughly cut out on the bandsaw, a standard office paper cutter works great for cutting 0.016 aluminum sheet. Here I cut as close as I can to the template trace lines, then I use the grinder and hand sanding to bring them to final shape/size:
I'll store these in inventory as they are for now as I don't have the bending forms ready yet and wont be building the flapperons for a while.
To continue towards starting my tail section, I found another couple of little parts I could make up while I had the scrap out. I'm also learning that it sometimes pays to bend multiples of the same part where required. The tail section call for two of these 35 x 40mm bent angles from 0.025, and I had the perfect piece to make it from. After cutting and deburring, into the bender they went:
This way they end up being perfectly matched!
I got several other small parts made as well that aren't pictured here, but like the quote says.... "One bite at a time".
Wonder what's for dessert?
Although I haven't been in the shop as much as I like the past couple of weeks, I continue to get there when I can. It's hard to be inside when the sun is shining so much outside (which means more stuff to do around the house), but the shop sure is nice and cool when it's too hot to be outside!
The wing root repair/rebuild is now complete, just need to clean up all the Sharpie marker notes:
Progress also continues on cutting some of the smaller template parts that I need for my 750 STOL build. These are wing parts (strut attachment brackets):
Yesterday, I finally completed the wing tank rear channel. Ron decided he wanted to return the fuel tank size to factory specs, so this necessitated moving the channel rearward and cutting down the original shorter to fit inside the tapering wing chord. This is the location where it should be according to the plans, the previous builder had half of this space for his wing tanks. Maybe that's why he purportedly ran out of fuel?
I don't have many pictures of the process, but here is the completed item riveted in place:
With this done, we'll be moving on to the wing tip extension that Ron wants done. While we plan that out, I started tracing out the templates in preparation of cutting out the plywood forming blocks required for my 750. It starts with a piece of plywood which Ron purchased for me as part of another project he is working on. We had discussed the need for only half a 4 x 8 sheet as some of the forms that I need Ron has already made and interchangeable with the 701. So I grabbed a half sheet from the woodshop:
Each form template gets traced out twice to make out each half of the forming blocks:
As you may recall from previous posts, it took a fair amount of time working in CAD and with Adobe Acrobat to print full size templates onto card stock. Some part templates are fairly large and don't fit on a single piece of 11 x 17 inch cardstock, making it necessary to break the template into 2 or more pieces. For the most part, it's long pieces like wing ribs that are the issue, like this wing root rib form template which is shown here taped together:
It's also helpful to pin larger templates down to ensure an accurate trace:
Just as I was pondering whether all my templates would fit on this piece of plywood and how to make that happen while trying to avoid placing cut lines on places with wood knots, Ron arrived back in the shop. He quietly asked how I was making out and I explained my dilemmas. Ron quietly grinned and told me the piece of wood I was using was actually scrap flooring from the other non-airplane project he was working on. My piece was still up in the woodworking shed.
Guess it's a good thing I didn't trace everything out yet and I haven't thrown out the templates, otherwise it would be back to the drawing board. Hehe... drawing "board"... I kill me.
Back in a few days.... :)
Husband, father and 911 dispatcher. Long time pilot with a licence that burns a hole in my pocket where my student loan money used to be. First time aircraft builder. Looking to fly my own airplane.