Fitting Lower Wings To The Fuse

in search for missing bends

Today, ended up messing around with putting the lower wing and the fuselage together...

Lower wings are set up at 1.5 degree incidence, 1.0 dihedral.

Started with that I realized that I mis-positioned the hole on the front spar and gear fitting. Simple fix :)

Next, came a lot of thinking and reading. Here's the problem.

The plans position fittings perpendicular to the longeron.

Fittings on the lower longeron

Holes are co-linear, and incidence is achieved because of the stagger in the attach holes on the spars. Airfoil chord, tilted up 1.5 degrees make these holes come together.

The problem is that spar sides then become non-coplanar with the fittings' faces; possibly introducing bad fit, play, misalignment, and whatever problems I can't think of.

Here's how the spars go 'into' the fittings. I circled the rear spar, since Ill use that for illustrating the problem.

Spars on fuse (rest of wing hidden from view not to obstruct

Now, looking at it from the tip of the spar towards the fuselage, you can see the angle between the fitting and the spar. That's because of 1.5 degrees of incidence.

Angles don't match == no fit.

This problem caused about an hour and a half worth of research with no results...

Firebolt and Pitts plans explicitly state either bending, or welding fittings to longerons at correct angles. Not Skybolt though...

Ended up posting on the Forum. Let's see what the folks say....

On a more positive note; I can see an outline of an airplane in this now ;) Made some virtual, mental airplane noises :)

Airplane!!!!

The only thing that scares me about flying is the drive to the airport.

Lower Wing Fittings and Torque Tube

cleanup, and more bending

For starters, cleaned up the torque tube; added all the hardware (thanks cwilliamrose again for AN hardware models!) and proper mates. Was a nice warm-up, and came out real well.

Torque Tube, Cleaned Up with HW

After that, added the lower wing front fittings to the fuse. Piece of cake! :)

Lower wing front and gear rear fittings

... and zoomed in.

Notice on the above picture how they interfere with the tubes of the fuse truss (geometry penetrates one another). There are a couple ways to fix that; plans just call for 'trimming in place'. Note to self: figure out if the weld should only be around the bottom longeron; or if to weld the top of the fitting to the vertical too?

The cool thing about SW is that I can "cut" in place; add a bit of margin on the real pattern for the fitting, and make it to fit without constant trial and error.

And then, lower wing rear fitting.. that one is tricky due to the way it's dimensioned on the plans (it makes sense plan-wise, since it maintains clearances between longerons and spar butts, etc; so hole positioning takes metal thickness into the account). Can't believe it took me 2 hours and a few tries to figure out how to model this right. Learning curves be damned :)

Lower wing rear fitting

Now, the reason for all that trouble is that getting the flat pattern out of that is just 1 mouse click!

Lower wing rear fitting

I think this was a great day. :)

"I don't mind altitude separation as long as they're not on top of each other."
-ORD ATC

Torque Tube Basics

for now, just the bare minimum

Started modeling just the very basics of the torque tube. The idea is to hang it on the fuse, attach the aileron pushrods to it, and check clearances in the wings (and finally get to start making them! :)).

Just a few screenshots today. Lots of time spent reading plans (haven't paid as much attention to Fuselage / Control Stick setup as I did to the wings).

Gladly, I had the truss model from way back when (I did it to learn SolidWorks Weldments feature).

Anyways, pretty pictures below.

Aileron Actuator Arm Sketch

... and model.

Torque Tube Collar

Very basic model of the Torque Tube (but all I need right now, minus the aileron arms)

Torque Tube on the Fuselage

And eyeball alignment check - fits!!! :)

An airplane will probably fly a little bit overgross but it sure won't fly without fuel.

Pushrods, bearings, and clearance

slowly getting there

In the past couple of evenings; have continued hanging virtual control system on the virtual wings.

Thanks to CWilliamRose from Biplane Forum, I now have quite a bit of models of AN / MILSPEC bearings.. REP3H5 included, but he didn't have REP4H6, so that had to be done first..

REP4H6 bearing model

Couldn't find a few dimensions; but my rationale is as long as the basic eye height / bore / shank are there, and the ball 'rotates', that's good enough for the purpose of my alignment checking, for now at least. Ill revisit if I start getting into tight corners.

Next, hung the Idler, bearings, cleaned up the model (funny, lower wing assembly is technically my first serious SolidWorks model, so I keep cleaning it up as I go, killing stupid things I did back when I didn't know any better).

Sigh... I will need to hang the wing onto the fuselage model to make sure the pushrod doesn't hit verticals -- clearance is there, but might not be enough.

Here's the wing model with the pushrod:

Idler, bellcrank, and pushrod -- there is clearance, but is it enough?

Here, it's looking at the rod from the tip, the rod is that white thingie right of the rib verticals

So, I guess, to the wing fittings and control stick assembled with fuse models tomorrow.

And to finish today off, here's the full zoomed out picture of the lower wing, as it is right now.

The wing

FAA Regulations forbid drinking within 8 feet of the aircraft and smoking within 50 hours of flight. Or is it the other way around?

The Shop Day

... and how it turns into two weeks

So, originally it was supposed to be the shop day. I was gonna clean and put together the compressor I picked up off a gentleman on Craigslist, and set up the air hoses, filters and such - and then, back to CAD. And then..

See, I was looking for a bandsaw. I wasn't in a rush, so I was gonna pick up a good used one; so I was watching Craigslist and such, waiting and waiting. After doing that for about 6 months and after I got tired of not having one; I finally said "screw it" and bid on one on Ebay.

I won it on Friday around 4pm; paid, and went home. Well; there, in my Gmail's Inbox, was a notification from CraigWatcher saying that yet another bandsaw ad was posted... I opened it up; and couldn't believe my eyes.

Someone was selling.. an 18 inch Grizzly saw for 250 bucks! I couldn't pass on it; and next morning was driving back with a 300 pound beast in the back of my car....

... and then, spent a week and a half cleaning it up. I polished the rust out of the table; changed some bearings, re-cut threads on the blade tensioning rod, added a 4 inch dust port (for whatever weird reason, Grizzly decided not to put a dust port on this particular model).

It also ran on the 220, so I had to add a 220 outlet to the shop... Decided to go all out; and added a 6 gauge run with 50 amp breaker, so that I can run a TIG welder off of it when I get one.

So now; I own two bandsaws :).

Here's the perpetrator:

The Bandsaw

Since we're talking shop....

Right now Im set up in the garage of the old house we bought about half a year ago. Dash (my beautiful wife) is working on designing a new house we're gonna build; and that one is going to have a good sized shop. We will build that house first and then demo the old house; so I could start setting up earlier than I thought I would be able to; which is certainly nice.

But; Im dealing with 40 year old electrical; and other fun stuff..

Here are some pictures of that garage, ordered historically, as I was setting up.

Just after washing everything with a pressure washer...

The beginnings of the storage spot

.. all that empty space :)

That's pretty much all my tools before I moved (the big red chest is new)

First batch of stuff - table saw, jointer, planer, drill press. Excited!

.. and set up!

Storage's getting a bit more crowded

Setting up lighting. All that wood is for the benches.

First bench - the frame is ready.

The benches are up - and this place is starting to look like a shop!

.. yep

Next, some 2x4s put together into a material rack. Cleared a lot of space!

Storage again

Air setup, router table, and The Bandsaw

Added some entertainment :) Also, the little Delta bandsaw on the bench

I like how this looks!

And here are a couple pictures of the tools...

Air setup is very simple, a compressor with a shutoff directly into an air filter, regulator, and 25 feet of hose on a reel. That reaches pretty much everywhere.

The Air Setup (very simple for now)

At some point; I measured the runout on the drill press -- got around 10 thousandths - no wonder why it was all vibrating when drilling deep holes!

Grizzly includes very cheap chucks and arbors with their presses... Gladly, the bearings have no play though. I ended up picking up a used Jacobs chuck on Ebay, and boy, what a world of difference! Used a SouthBend arbor picked up on Amazon.

The Jacobs Chuck

I wanted a router table; but didn't want to pay around a grand for the one I like (and cheap ones are just.. crap, honestly); so I built one.

Top is two sheets of 3/4 MDF, laminated together. White Formica is laminated on top, bottom, and sides. All done with DAP Weldwood contact cement.

I bought the insert plate (though in hindsight, I should've just bought a hunk of aluminum and made it myself).

It still ended up being a bit out-of-flat, so I built a leveling system into the base (two bolts on each side are pulling the top "down", screwing into holes in the top with threaded inserts; and there are two screws pushing up on the top in the center of each long frame side. All that allows me to work out any non-flatness out of the top.

Fence is 3/4 ply; and the router sits in the box under the table. The box has 4 inch dust fitting epoxied on it on the other side (and the fence dust collector feeds into that fitting too).

The Homebuilt Router Table.

If it doesn't work, rename it. If that doesn't help, the new name isn't long enough.

Bellcrank and Idler

Bending and twisting virtual metal

It's almost 5 am and Im finally done with the bellcrank alignment! Phew.

By the way, sheet metal stuff in Solid Works is amazing! You give it the bend lines, radii, and a couple more parameters; and it automatically creates both the bent item; as well as the flat pattern. Print the pattern, glue, and start bending -- it will show you which line, how many degrees, and in which direction to bend. Ill post one of those final drawings later, when I get around to printing them and bending some actual metal :).

Anyway...

The night started quite jolly with me whipping out the idler arm with it's bracket. Looks pretty neat, eh?

Aileron Idler Arm and Bracket

And then, back to the bellcrank hell. I had it modeled back in the days, and the "jog" bend 1/2 inches down made. Here's how busy the sketch with all the radii and holes looks BTW; pre-bending.

Bellcrank layout

Anyway, with all the sheet metal awesomeness SolidWorks doesn't know how to twist. You can twist a model by using deformation, but at that point all kinds of shenanigans begin to happen. For example, all faces of the model stop being planar faces (meaning nothing can be sketched on them, and sketch is how you start defining a feature (part of the model)); for some reason I wasn't able to put a reference point into the center of one of the holes, etc. (I ended up drawing that point finally by projecting that hole's centerline onto one of the faces; that did work for whatever the weird reason Solid Works gods must have).

Bellcrank, bent and twisted

And after fiddling with it for about an hour, I was finally able to position everything. The plans don't specify where the bracket should be, so my educated and logical (yes, mr. Spock?) guess was that it should be so that the aileron pushrod connecting bellcrank to the alieron hinge is aligned and straight in the "aileron neutral" position. So I used the aileron hinge center as the reference; squared the bellcrank and aligned it that way. Note the blue line (that's actually a plane bisecting the aileron hinge), and the Point1 (that's that wretched point on the twisted surface that took me so long to figure out). That's what I used for alignment.

Bellcrank mated and aligned with aileron hinge

Coming up, putting in the idler, all the pushrods, and checking clearances with rib truss throughout the full range of motion. I strongly suspect that I will need the control stick's model on the fuse to do that, since that's what the other end of that pushrod attaches to. Oh man... gotta love those dependencies. That just means that I will have to do that model earlier than planned. Oh well. I like Solid Works anyways...

Tomorrow's the Shop Day! Gotta clean and put that compressor together.

OK 5:11 AM; time to go get some sleep :)

Aviation has created many millionaires, primarily from the ranks of multi-millionaires.

Aileron-To-Rib - Alignment

Fixed mis-alignment in ailerons

Today, got only about an hour and a half for CADing. Re-opened my Lower Wing model, 50% thru or so, and started remembering things and checking things around.

I was right at a point when I hung the ailerons on the wings, and this time was re-checking the alignment again, only to find that they were off! Looked like they were lower than the rest of the wing ribs, by about 1/16th. Clearly visible on the screenshot below.

Black lines are aileron outline, orange lines are wing ribs

Started digging around and re-checking the hinges, holes, etc, with plans. The 'spar' side hinges are the most complex ones, and they were fine.. When checking the aileron assembly though, noticed this, which struck me as odd (and a bit illogical):

Aileron hinge sticking a bit 'above' the spar

Notice it sticking up? 3/32nds! Close to 1/16th. Arguably, there will be the filler there, but it still seems illogical (yes, mr Spock? :) ).

Anyways, moving the spar attach holes on the hinge up by 1/16ths (plans call for 3/8ths between the top of the hinge and the top hole center), so 5/16ths it is. That moved the whole aileron up on the hinge, and therefore, relative to the wing, and voila - a perfect match!

Match!

Yay! A perfect match.

Now, I know that in reality I will be drilling holes in spars in place based on the pilots in the hinges (or the other way around, hinges based on holes in spars (damn.. Im yet to decide.. :) ); but I'd rather start 'clean'.

You start with a bag full of luck and an empty bag of experience. The trick is to fill the bag of experience before you empty the bag of luck.

B-Log, The Nerd's Builder's Log

How I went about b-logging

Note: this article was updated in 2018 to reflect changes I did in version 2 of B-Log. I want to have a single article to link to in case people are interested...

Notes on the update are here.

/project-one/section-one/

        2001-01-01-entry-one/
                    entry-one.rst
                    picture.jpg

        section-one-log.log

/project-one/section-two/

        2001-01-02-entry-two/
                    entry-two.rst
                    picture.jpg

        section-two-log.log

/project-two/section-one/

        2002-01-01-entry-one/
                    entry-one.rst
                    picture.jpg

/project-two/section-two/

        2002-01-02-entry-two/
                    entry-two.rst
                    picture.jpg

2011-01-01 | Some Summary Here       | 1.02
2011-01-02 | Some Other Summary Here | 2.02

A checkride ought to be like a skirt, short enough to be interesting but still be long enough to cover everything.

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