CafeenMan

Maybe it has some dust masks so you don't breathe that carbon fiber dust you're creating while sanding.

nickbee

My Feedback: (7)

Funny thing is I was contemplating some type of “respirator” and eye protection for when I work on carbon. Any suggestions you guys have would be great.

CafeenMan

Carbon fiber is very bad stuff. You seriously don't want to breathe the dust when you sand it.

I wore gloves and a fiberglass respirator (3M #N95). I cut the spars using a hack saw and then sanded the ends on my larger disk sander with a vacuum attached (wearing protection throughout the entire process).

When I was finished I put the tube in the vacuum hose to suck out stuff inside but that wasn't enough so I went outside and used high pressure from my air compressor to blow through the tubes. Carbon fiber scares me a lot more than the cigarettes I smoke.

nickbee

My Feedback: (7)

The next step is emphasized in the manual. Larry stresses that the accuracy of the forward spar to the root rib will effect how the rest of the wing is built. This makes sense since the “combs” will line up with the root rib and any deviation from 90 degrees will be duplicated all the way down the wing.

I line up the last rib dry over the plans. This helps to ensure that the spars are going to line up with the root.

A jig is provided in the kit just for the purpose of aligning the forward spar to the root rib. I start by using this jig them double-check with squares and fixtures of my own. By aligning everything on the plans and using SR’s jig the results are very accurate. I lock everything down with magnets and use 30min epoxy on ONLY the forward spar. The rear spar and leading edge will be glued after the front spar cures and the 1/4” washout spacer is positioned.

Here’s a stupid question. The spars fits snug into the root rib holes. How will I know if the bond is good enough? I coated the rib and spar, assembled, then wiped away the excess. But with the tight fit how much epoxy is left holding on? I plan to let everything cure overnight then give the spar a test to see if the bond is good.

nickbee

My Feedback: (7)

I did a quick “twist test” on the forward spar this morning before proceeding and everything seems solid. I figured maybe I’ll stand the wing up when its done and put a small epoxy / microballon bead around the spars where they meet the root rib. But it’s probably not necessary.

nickbee

My Feedback: (7)

Next it’s time to set the spar blocks and wash-out spacers in the proper position before anything else is glued. The blocks are positioned flush with the leading edge tube as noted in the manual. My assumption is this sets the proper wash-out spacing along with the ¼” spacer placed under the rear spar (noted on the plans). Next the root rib is glued to the rear spar and leading edge. The wire / rubber-band clamps help keep the leading edge seated nicely.

nickbee

My Feedback: (7)

Now it’s a repetitious process to position the ribs and glue. I use the combs for rough placement then lock the ribs with the magnets before gluing. Since I did not purchase $300 worth of large magnets from Lowes I work one rib at a time. I’m not in a rush so this is ok with me (and a relaxing process). Don’t forget to pick up plenty of Teflon-tube tips for controlling the CA.

nickbee

My Feedback: (7)

Larry mentions that the ply ribs might be a bit warped and to hold them straight while gluing. I find that the rectangular magnets I am using are not up to the task so I break out the magnetic jigs I just got from arifieldmodels.com. They hold the stubborn rib perfectly over the plan while the epoxy cures.

CafeenMan

That stick on your rib comb was a good idea. I didn't use the comb and lined everything up over the plan. I would have sent you my "leading edge clamps" too if I'd thought about it. I saved them in case I ever build another of these but for now they're just sitting around.

It's pure luck that the fixtures fit between the ribs. They aren't designed that way, but I did the same thing to hold some of the ribs.

CafeenMan

Oh.. one other thing. I see you're using the Pacer "Z-Ends." Those things are great and they only fit the Pacer bottle which is why I only use Zap. I hate the bottles that just have a spout on the end. If it clogs you're screwed. With Z-Ends you only have to pull off the tip, throw it in a jar of acetone and put on another one. A few hours later the one in the acetone is ready to use.

I bought a container of Z-ends years ago and they're still going strong because of soaking them instead of tossing them.

nickbee

My Feedback: (7)

That’s a great tip on the tips! My tip packs have never lasted years!

And the funny thing is I still have my “leading edge clamps” somewhere from my Cutie. I figured it would be quicker to make a new set rather than look for them.

nickbee

My Feedback: (7)

Now that the main ribs are glued in place it’s time to attach the trailing edge. I’ve been scratching my head on how I was going to accurately tackle this task. The issue is that with the wash out built into the wing it can’t be done flat on the building board. The manual states to hold the trailing edge in place while you tack it with CA. That would be ok I guess, but I want to use Titebond for all my balsa-to-balsa connections. My 1st thought is to use clamps, but a quick experiment shows the trailing edge stock does not sit flat on the ribs.

The solution I come up with is to stack magnets under each rib then use playing cards as shims to create just the right amount of clearance for the trailing edge to slip in snugly. Each rib gets it’s own magnet / card stack depending how far down the wing it is. The amazing thing is that each sequential rib is about 3-4 playing cards higher than the previous one. This tells me the wash out has been built consistently into the wing.

I use a Q-tip to apply the Titebond. If there is a better method please share…

The trailing edge gets slipped under the ribs with a final wax paper shim to make sure the cards do not become a permanent part of the structure. A few card stacks get adjusted for proper tension then magnets hold the trailing edge stock firmly to the back notch of the rib. A quick glance down the trailing edge shows that everything is seated nicely and there doesn’t appear to be any warps in the trailing edge.

BTW, I didn’t sand the trailing edge side of the stock yet. I’ll wait to add the doubler then sand them together.

Oh, and I with I could take credit for coming up with the idea to use playing cards as shims while building. But that’s something I picked up from Harry Higley’s book, “Mostly Mounting”.

nickbee

My Feedback: (7)

Next the trailing edge doubler gets glued on. I use finishing epoxy since I’m going to consider this a lamination and I want a warp free cure.

nickbee

My Feedback: (7)

Here’s an instance where I’m going to deviate from the manual. The balsa wing tip edging (top and bottom) is added after the wing tip is glued to the wing in the manual. I’m doing this pre-game for a reason that will clear later. Take note that the top edge is longer than the bottom. Everything gets a coat of finishing epoxy and the weight treatment.

So far my only gripe about the kit is the lack of certain side views on the plan. It makes figuring out which parts go where a little more difficult. But I guess if you just follow directions it is never an issue.

nickbee

My Feedback: (7)

The bottom of the aileron drag spar goes on next. Unlike the trailing edge there are almost flat surfaces to work with so I use clamps. I’m also switching to 30 min epoxy for the drag spar “box” since this is an area of stress on the wing.

Note! Make sure you put this part on the correct way over the plans!

nickbee

My Feedback: (7)

There are 2 verticals to the drag spar. The manual has you installing these one at a time. For the conservation of time and increased accuracy I’m going to laminate these pre-game. They get the normal finishing epoxy and weight treatment. They will be ready to go tomorrow when the clamps some off the bottom of the aileron drag spar.

abufletcher

Great technique on the laminations. I had some trouble with warping doing the balsa to thin ply laminations of the TE on the Snipe's wings. I wish I had thought of using weights (and epoxy). I used titebond and the moisture cause some bowing.

nickbee

My Feedback: (7)

Ya Abu so far it’s worked like a charm. It even straightens out slightly warped pieces.

nickbee

My Feedback: (7)

Looks like Santa visited me a little early this year! My converted G26 came in today from rcignitions.com.

First a quick mock-up to the firewall and plans show that I should not have any clearance problems with the slimline smoke pitts muffler (whew). It appears there will be about 3/8” clearance from the muffler to the fuse. But the muffler “stacks” will have to be cut down. The good news is Ralph from rcignitions confirmed that is not an issue with engine performance or sound.

Some other details of the engine; the throttle arm is repositioned and a ball connector is already installed for a simple pushrod straight through the firewall. There is a setscrew on the throttle arm so it can be properly positioned for the pushrod install. That piece of yellow tubing hanging off the carb is the choke “handle”.

The battery connects via an RCA type jack. A radio shack “audio cable” is included for the connection to the battery.

A few photos show the new wiring and coil install. Finally I believe the prop bolt is beefed up from stock. I’ll be working on a test stand over the next few weeks in my spare time (ya right). I’m curious on the operation of the engine and the smoke system. I’d like to learn its operation and test the smoke pump before installing it in the airframe.

This weekend I finish up the left wing…

feep

The wing looks good and the engine set up appears well thought out. You certainly sound like a man with a mission. AS I sit here admiring your table set up I'm reminded that I am at a standstill with my D7 upper wing until I can find a board or table long enough to join it (88") Not to worry I can work on lower wing panals until after Xmas and start looking for one.

nickbee

My Feedback: (7)

Feep,,, What about picking up a door from Home Depot for a quick and easy solution? And that fact that the slimline pitts worked out was pure luck, not thought out

nickbee

My Feedback: (7)

The next step is to glue the laminated verticals of the drag spar “box”. Time to mention a flaw of laser cutting. While the parts are VERY accurate the edges are not always perpendicular to the flat surfaces of the wood. My guess is this has something to do with the angle of the laser as it “cuts” through the wood. In most cases thins is not an issue. But when edges are matting surfaces it’s something to look out for. The 1st pic shows this flaw when you mate up the verticals to the ply rib. A quick touch on the disc sander and the problem is gone. This is a small issue compared to the accuracy of laser cutting, but it’s something to be aware of.

The top of the drag spar is dry fitted to help with alignment, and the verticals are clamped into place.

The last pic shows a detail of a rib mating up with the dry-fitted top of the drag spar box. Not only is the fitment perfect but also note the bit of added material to the top and vertical. The will allow for a perfect sanded finish following the shape of the ribs. Nice Touch!

nickbee

My Feedback: (7)

There are two 1/8” balsa rectangles that will be glued between each rib and the vertical of the drag spar. This material will give the hinges some more meat to hang on to. I’m laminating these now so they are ready to go tomorrow. 5 sets are prepared…

feep

Nickbee, I"ve been following this thread and it finally occured to me that something was different. I'm guessing you're using some other adheasive other than CA. Am I correct ? Or are the clamps and weights to prevent warping?

I'VE considered the hollow door idea but the D7 wing is 88 inches and most hollow core doors are not long enough. 80 inches?

My wife just asked me why I'm measureing the cellar door and after an explaination I think the seeds of a new workshop have TAKEN ROOT!!

nickbee

My Feedback: (7)

Ya Feep I'm using finishing epoxy where laminations are involved (many places) to avoid warping. I chose to use epoxy on the aileron drag spar also for some added strength.

mmm standard size door is 80"? I feel a special order coming on soon!