May 31, 2005

Plexi Finish


I've tried sanding edges but I have finally settled on the draw knife method to remove nicks and grinding marks. The trick is to ALWAYS use a negative rake angle... You want to take marks out of the edge not put them in. The Bowie here was homegrown from a leaf spring.

May 30, 2005

Long Reach


Finishing up some of the miscellaneous details laying around for the cockpit. This shot shows off the L-O-N-G-reach yoke we picked up last summer at Oshkosh to finish some of those hard to reach spots.

May 29, 2005

Gator Time




Boy, that alligator squezer we bought at Oshkosh two years ago sure comes in handy sometimes. You have to rivet the skin on first (i.e. the day before) before you can set some of the bulkhead rivets or you will find yourself in a riveter's trap. With the skin on, it was time to go back inside the tunnel and get the last couple of 1/8 rivets that had to be set.

May 28, 2005

Skin Wrap


The skin that wraps around the rear window has always impressed me as begging for a hanger rash accident in the making. So we were quite pleased to finally get to rivet it on. Boy is it cramped in there, but not as bad as I thought. I made up a plywood panel to lay on, and Cathy ran the gun and did the bucking bar chores.

May 27, 2005

Last Prep


Deburred dimpled and primed the rest of my small parts and the parts for the canopy. This is probably the last time I will need the big c-frame press to dimple the sheet metal for riveting.

May 26, 2005

Patterns


Working on build-up of a set of patterns to comprise a metal fairing for the front to the canopy bubble. This will be a two piece affair. I'll try anything at least once to minimize my exposure to working with fiberglass... I used to machine the stuff years ago, and I still remember itching!

May 25, 2005

Experiment




Besides drilling some more harness brackets in place using the right angle attachment on my dremel tool, I cooked up a little test jig to see how accurate logitech joystick controllers are. My micro steppers for the mill divide 360 degrees into 2000 steps... So, since I do not have an indexing head I hooked a 150Kohm pot to the saddle's stepper motor and moved my regular computer out the garage read the joystick output data.

The joystick reports motion scaled on the interval from 0 to 1 with one axis being -1 to 1. My readings showed the controller outputting on the 0 to 1 interval with 0.01 being the minimum increment. Now the bad news: With an external resister alligator clipped to the circuit the noise is in the range of 0.03 and seems to drift up and down over time making my suspicios of (a) noisy device and (b) something funny going on in the chip's a/d sampling. The tiny pots native to the controller seem to work on 0.01 increments by and large without the noise.

Even with the noise, the accuracy is probably more than sufficient for use tracking actual control surface positioning such as the flap.

May 24, 2005

Belt Harness


After some epic battles with the cars, I was able to start on fitting the extra seat belt harness location between the legs. Something tells me this job would have been easier before putting the fusalage skins on.

I had lots of fun with the Elantra... Seems as though its clutch works backassward of the usual fork press on the throughout bearing which presses on the pressure plate. Oh no, those sneaky Korean engineers had to come up with a clutch where you pull on the pressure plate with the fork/throwout bearing! Which means you can pull like all heck and nothing comes apart until you do the magic trick of removing the slave cylinder actuator arm so the fork can over-travel and disengage said transaxle from said engine.

May 19, 2005

Light Duty






Last Thursday was the last day I worked on the plane. I'm slowly working off the odd rivet here and there, and have a tray of parts to do the final prepping on for priming and installation. I'm planning on making a pattern from the top skin of the canopy frame to see if I can make a metal fairing for the front of the canopy instead of the usual fiberglass lay-up.

It's firewood season now that the logger finished taking some pines off the property. I skidded some logs up to the front of the house for chain sawing into fire wood. It's definitely black fly season, too! I've been stuck under the Elantra for the last couple of days putting a new clutch in... Man do I hate the smell of Hypoid gear oil!

May 17, 2005

Bucker's Eye




Tuesday night we finished the riveting on the F-771 forward top skin. It isn't as cramped under the hood as I had feared but it isn't a cushy sofia neither.

May 16, 2005

Upsy Daisy






We got most of the forward top skin riveted tonight. The firewall was the trivial part with the aligator squeezer. The rest of it was fun with Phil on his back on top of the main bulkhead for the wing mainspar with my legs draped over the side, my head under the skin and one arm curled over the other side to get some leverage to hold the bucking bar under the skin while Cathy ran the rivet gun from above.

Wasn't really as much of a Harry Houdini session as I had feared, but we called it a night and we'll finish the outboard rivets on the left side tomorrow... Assuming my neck doesn't turn to rubber tomorrow...

The photo a few days ago showing a pile of wiring and circuit boards was the innards of a Logitech Extreme 3D-Pro joystick. I'm looking into the feasability of using it to track the position of the elevator, rudder, aileron, and flaps, plus stick hat switches.

I also picked up a breadboard at Radio Shack so I can start running some tests on the analog device's rate sensor I picked up a while back.

May 15, 2005

Bucking Bar




Machined a simple bucking bar to get under the main longeron and set the rivets. Other than this bar I only needed some simple 1/4 inch thick steel bars to get at a couple of the more cramped space locations.

At this juncture we are doing finishing details to get ready to rivet the top skin on. I have decided I want the top skin buttoned up before finishing the canopy as I found (with the gas struts) the canopy position can be move slightly when just the clecoes are used.

May 14, 2005

Riveting Details







Decided it's finally time to rivet some of the parts for the on the fuselage before going any further on the canopy. Riveting the to top rail pieces turned out to be easy, but I'll need to make a bucking bar to set the rivets that go through the main longeron. Started fitting the air vents to the fusalage, and I'll seal those in place and rivet them.

May 12, 2005

Gas Struts







Finally finished the small parts to mount the gas struts to hold the canopy open. Took about two days of fiddling to machine all the parts and a drill jig to set the position of the front mounts. A funny thing happened after I drilled everything and installed the struts: The gap between the canopy and rear window opened up! Those struts do a lot of prying on a clecoed assembly and even more when you do not have the front top skin clecoed on.

Upshod: You do not want those gas struts anywhere near the fusalage while you are fitting up the skirts, etc. - Until everything is riveted finally into place. Of course, the final riveting of all the fuselage/canopy parts is starting to look like the proverbial chicken and egg problem... Who goes first and after that what order?

May 11, 2005

Field Trip





Dino Vlahakis, our EAA chapter's flight advisor, came by for a visit and we went over to the grass runway at Plymouth, NH to visit Bill Grady, a retired airline pilot, and his RV-7 which is nearing completion.

Bill had previously built a very nice RV-6 back in the days when you had to lay out and then drill all the holes. I won't bore everyone with samples of my 40-odd intel shots of Bill's RV-7 or the brand spanking new (as of May 1, 2005) RV-9 parked on the grass awaiting inspection to get an airworthiness certificate by Mr. Malcomb Brawm of Hebron, NH.

Those RV's just keep popping up, what a great airplne kit!

May 10, 2005

Small Parts

Back making small parts for the lift struts for the canopy. Had an interesting EAA Chapter meeting this evening with a presentation from an engineer who worked on the Garmin glass cockpit display's attitude reference system.

Speaking of attitude reference systems: a little while back I received the following info on a new system developed in Europe:

We are pleased to inform you about the release of the MTi, the world's smallest Attitude and Heading Reference System. The MTi is the successor of Xsens' MT9 Inertial Measurement Unit and its main improvement is the internal computation and direct output of the Pitch, Roll and Heading angles with 0.5 degree accuracy.

The MTi will be released at the Sensor + Test tradeshow, to be held from May 10-12 in Nurnberg, Germany. Together with the MTi, we introduce the even smaller MTx 3DOF Orientation Tracker for human motion measurement. Please, visit http://www.xsens.com/mti_ahrs.htm or contact me for more info about the MTi.

May 09, 2005

Try Again



The ejector rods for pulling the pins on the canopy hinge were both machine 1/2 too short... Speedy blueprint reading on my part... So I ordered some new steel tubing from aircraft spruce and got to make a second set.

May 08, 2005

Nice View









Finished the basic countersinking and hole prepping for the rear window and then the initial trimming to get about a 1/32 inch gap between the canopy and the rear window. Cathy got first dibs on sitting in it with the canopy on. It sure gets warm under that canopy. Time to start working on the gas strut mounts to hole the canopy open.

May 07, 2005

Rear Window



Finished the initial drilling of the back window and the countersinking and dimpling of the rear edge. The procedure I have been using is to set one countersink cage to the countersink depth for the screw and sheetmetal, and one for chamfering the inside edge slightly to remove the stress riser. At this point, what's left is the countersinking on the roll bar, the trimming for the line between the canopy and the rear window, and the internal aluminum strips to finish securing the rear window.

May 06, 2005

Easy Day



Taking my time on the rear window Friday. Have the rear of the canopy trimmed nice and hopefully we can get the rear window to match.

May 05, 2005

Plexiglass







Boy, sure glad a I bought a full set of plexiglass drills to experiment with. I used only one... The 1/8 inch drill to drill the plexiglass for the canopy to the frame. It's tricky in that you run the 1/8 plexi drill and then have to take everything apart, put your regular drill bit in and then drill the aluminum, debur, then cleco everything back together and check the fit.

I experimented with a 5/32 plexi bit to open the hole up for the 6-32 screws using some scrap plexiglass. What a disaster that was! The plexiglass bit releif on the back side of the cutting surface is so great the drill grabs and drives faster than a regular bit and dinner plates the back side of the hole i.e. a big engraved invitation to a CRACK... Argh! So we did some experimenting and found you can run the 1/8 plexi hole. Did that and then counter sank the outside edge to fit the screw head, and with a second piloted countersink and countersink cage I set up to countersink the back side.

Just a little bit to break the sharp edge left from the 1/8 bit and leave some chamfer in the material if I run a conventional #27 drill through the hole. Just to make things safer I stoned the #27 drill to get rid of the positive rake angle and take some of the bite out of the drill. Worked like a charm.

Seriously, anyone thinking of double drilling with drills ground for plexiglass should run some tests first then rethink their approach. Other than the fact that I had to use washers for shims on some parts of the frame it came out really nice. Boy that sucker is heavy, and I can see why they put gas struts to help lift the canopy.

It's getting to be spring and Kaz and Woody the cat are getting "frisky"... That plothound/lab just loves to "play" with ol woodster! So far all the critters have been behaving the plane room.

May 04, 2005

Alignments





Decided to bite the bullet and rivet the forward bulkheads in place prior to drilling the canopy. Not the easiest riveting, but I can see that installing the top skin later will be an interesting experience. Remasked and installed the canopy for drilling, but held off, as I want to check the fit a bit before drilling. Looks like the frame may need a shim. I have it taped at the front a bar of steel clamped at the back keeps the fore/aft alignment in place. You move one thing and everything else moves out of alignment unless you backstop the position. The clamped steel bar on the back of the roll bar worked very well at controlling the location wiggling.