A really productive day in the shop today. Managed to finish off the last flapperon (inboard right). A milestone part of my build is complete. Here is a family pic of them all together:
The opposite end shows the open ends of the outboard flaps (on the left below). This is where the aerodynamic tip inserts will go during final assembly:
With everything complete on the flaps, I stacked them up for wrapping in plastic sheet to protect them:
Once wrapped up tight, they go up in the barn for storage until needed back out for inspection and set-up on the wings. Stacked on some of my rolled aluminum, from botton to top, my completed assemblies are stabilizer, elevator then flaps.
One thing I want to try is 3D printing some of my parts and the aerodynamic flapperon tips are the ideal candidate for this technology.
I wrote previously in my blog about 3D scanning some original parts and using the 3D model from the scan to print them. I discovered that although my home server has enough processing power and memory for 3D scanning, the video card currently installed does not quite have enough chops for the job. A replacement I ordered arrived last week from Amazon and I set to the task of installing it. For some reason, the server will not power up (it has been sitting idle for a couple of months while I waited for the new video card). Bummer, I will have to investigate this further before I can start experimenting with 3D scanning.
Meanwhile, our local library allowed me to bring home their 3D printer. It broke several months ago and they have no money in the budget to repair it or hire someone to fiddle with it, so I offered to see if I could get it working. No idea at this point what it will take to get it working (it is an early model) but I told them in return for trying some prints from my 3D scans, I would both work on getting it working for them and pay for any parts that might be needed. From what they have told me, the extruder nozzle is clogged and the print bed may be damaged.
Very happy to have the flapperons done. Next on the build table will be the slats which I am led to believe is one of the more challenging sub-assemblies of the entire build. But that is what I got into this for - to learn :)
In an upcoming blog I document the 3D printer un-boxing, rebuild and repairs.
Thanks for following along.
Good progress since the last blog entry. I finished up the second outboard flap and started on the last inboard one.
The skin is bent correctly and the rivet lines are laid out:
With the skin riveted in place, the nose skin is rounded over. Lengths of wood under the ratchet straps draw the skin down tight:
With the skin in place over the spar, rivet holes are drilled, alternating out from the middle of the spar to the ends - this helps fasten the skin evenly and avoid twisting.
With all holes now drilled, it all comes apart (AGAIN) for final debur, cleanup and priming:
The spar is primed on top and bottom flanges, the web in those places where ribs attach:
The skin is also cleaned, debur and primed:
I'm pleased with my attention to measuring detail. Rivet holes are perfectly centred in the nose rib and the flap pickup angle is cleanly passing through the skin:
All buttoned up awaiting final rivets before heading to storage and later inspection:
Outboard flap splice plate, drilled and primed, ready to be riveted to the inboard rib:
Final rivets complete on the underside and flap splice plate added. Lined up on the bench with it's opposite wing mate. Really pleased how these outboard flaps turned out.
So here is an updated "completion" diagram. 3 of 4 flaps complete!
Onto the second inboard (and last) flap. To fold the trailing edge, Ron helped me clamp it down using a long board. A 1/8th inch spaced inside prevents the trailing edge from getting crushed. The secret here is gently tightening each clamp in turn so the trailing edge remains straight and true. The square steel pipe helps keep everything down even
It didn't squeeze it down quite enough, but close enough to be drawn down flat to the ribs:
You may recall from an earlier post (see here) that it took a while to figure out the correct toe-in angle at the root of the inboard flap. In order to keep them the same and allow for any slight deviation from the plans, it's best to copy the first one I made. To do this, I used an adjustable angle protractor, measuring the trailing edge and transferring it to the skin of the second one:
After measuring again I laid out the rivet lines on both the top and bottom of the flap. The root and tip ribs already had holes in them from a previous attempt to skin it, but that first attempt led to a bad twist in the finished flap (long sad story). Rather than make a entirely new rib, I used the duplicator to match the new skin holes. With a couple on each end done, I took the skeleton back out and pre-drilled the skin rivet holes out to A3:
With the spar in place and square to the skin, I drilled through the skin and into the ribs, using the red centre lines on the rib to keep them square. Working up from the trailing edge and out from the middle keeps the skin nice and flat and straight, the weight of the square steel tube helps immensely - much better this time!
Next up, I'll flip everything over and begin the process of riveting the bottom skin to the ribs and begin bending the nose skin over to meet the spar, including laying out the flap angle pass-through holes.
One more full day in the shop this week should finish off the flap assemblies.
Thanks for reading, soon I'll have something new to show you besides flaps!!
It's been over a month since I last posted to the blog and I'd like to say I have a lot new to report but I don't.
Covid continues to limit travel but I still have access to the shop. I've been feeling a little discouraged lately about my airplane build project. It's getting done but sometimes it feels everything is moving slower than I thought I'd like when I started this journey. Perhaps it's the overriding doom and gloom of media, news and society right now bringing me down.
A couple of days ago, a story was posted to a blog I follow and it reminded again me why I'm building not just buying. It's about learning and mastering my passion, not about instant gratification. If I keep reminding myself of that truism and how much I enjoy being in the shop, maybe I can also remember that no matter how much no progress is, no progress is just that. Some progress, even a little gets me closer.
Anyhow, I have been getting to the shop this past month. Had a couple weeks of back soreness that continues to linger, but feeling better enough now to work on the plane regularly. Might as well, not much else to do at the moment.
A regular reader of my blog asked me for a picture of the flapperon control horn complete and attached to the inboard flap. Here it is, final riveted to the root rib, prior to closing up the nose for storage. I realized when I was looking for this picture, I had a few others from the past couple of weeks. I'm onto my 3rd flapperon (the 2nd inboard one) so I apologize if the order of the pictures is confusing. They really are all the same build sequence as what I've previously posted, but I'll add some comments to each,
Laying out another skin with the biggest straightedge you've ever seen. The weight of a square steel tube keeps it in place, small finger clamps at each end can't do the trick on their own:
An important aerodynamic principal is to keep all flaps exactly the same dimensions (I'm very close to the plans, but not exact). To accomplish this, I used the completed inboard flap as my template to lay out the next skins and where the skeleton sits inside the skin:
I used the bender to gently form the trailing edge past 90 degrees, then a wide board to press it down flat. Small wood pieces screwed to the table kept everything in place for the press down:
Here is how I drilled the flap pick up angles to the nose rib. Started with A3 moving up in hole size to A4 then A5 ensures a nice clean and round hole for riveting later. While I had them out, I did the remaining 3 flapperon skeletons the same:
With the skin bent, rivet lines laid out and confirmed by dry fitting the skeleton, I drilled the upper skin to A3, using a scrap piece of plywood as a backer to prevent damage to the lower skin (it's very easy to do, not much room between the two!)
Using the skin holes as a guide, I lined up the ribs and drilled them out to A3. The steel tube keeps things flat and tight. I also did the spar at this point to A3. I leaned later to wait on the spar holes until AFTER I rolled the nose skin around.....
In the picture below, the nose skin is already pre-bent. Here I've flipped the whole thing upside down to rivet the lower skin. Again, I used the steel tube to keep everything tight, I also clmped the trailing edge down to the bench under some strips of wood to help secure everything:
Ratchet straps draws the nose skin over. If I'd been smarter, I would have waited to drill the spar holes once both skin edges were in place, but using the hole duplicator worked ok. I'll do it that way on the next ones.
The outboard flap sections do not have a tip rib. The tip is occupied by a fairing that I've yet to make (3D print!?!?). To help keep the shape of the nose correct, I inserted a piece of steel tubing that approximates the curvature of a tip-rib nose if it were in place. This worked well to keep the skin straight to the spar:
With everything drille dout and square, all holes are upsized to final A4 size and then the whole thing comes apart..... again.
Clean everything up using purplle ScotchBrite pad and a little acetone, ready for priming:
Once the primer is dry, everything gets assembled again. At this point I added the flapperon connection splice plate on the outboard flaperron. After fitting, it too was primed. Again, the matching bolt hole in the splice pate doesn't get drilled until later when mounting both to the wings for final adjustment:
So, here is an updated pictogram of what is complete (in blue), a good barometer of progress I suppose:
Moving onto the 2nd outboard flapperon, it's pretty much wash. rinse, repeat. I did take some time to check the straightness of the flapperon spar. I set it up on the steel tube and used heave steel blocks to reference against. This gave me the chance to verify the measurements and ensure ther was now twist in the spar (a common issue with scratch build parts) that could lead to a twist in the flapperon once it is skinned:
Laying the skeleton on the skin gives an easy reference to where the rib and spar rivet lines will be:
The trailing edge is carefully pre-bent in the bender, then.....
..... folded over using a long board and down pressure squeezing. Inserting the skeleton for fit confirms everything matches the previous 2 flapperons:
Top side riveted to A3, nose skin pre bent and flapperon flipped over to river the lower side (just like the last 2):
With the skin in position, flapperon pick-up angles can be laid out on the skin and cut out (I "think" I already showed this previously?):
It's nice to have the company of Ron's dog Maggie in the shop. Company is probably too polite - she's more of a supervisor!
The third flapperon is now almost complete. One more inboard one to do, but I was wrong when I thought the 2nd, 3rd and 4th would go quicker. It doesn't. But progress is happening and I'm happy about it.
Maybe it was a sign of brighter days ahead, but the other morning when I entered the shop, I'd thought Ron had left a work trouble light on in the Cessna cabin:
Turns out the glow wasn't man-made at all (trouble light or fluorescent).... it was just the sun streaming in the window of the shop roll-up door. Life is beautiful isn't it?
In closing this blog entry, I want to quote the author of the blog I spoke of reading the other day:
“At any real level, flying is not a sport, a hobby, a pastime nor entertainment. It is An Endeavor, worthy of every hour of your life you invest; Those who dabble in it find only high cost, poor reward and serious risk. They are approaching it as consumers. Conversely, for those who devote their best efforts and their serious commitment, the rewards are without compare.” -ww-2006
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.