Worked on pitch controls

September 4th, 2006

Not much got done on the airplane today because I was tired. However, I did figure out what was wrong with the F-789 forward elevator pushrod… it's not that it was too short to allow sufficient down elevator travel, it's that the control column was hitting on the seat ribs. I dremeled out some small bites from the F-716 seat ribs, just enough to allow full forward stick plus about 1/16" extra for clearance.

Another photo of the other side. The duct tape is to protect the finish on the control column.

I likewise had to trim the removable parts of the two center seat ribs:

Once I had full stick travel, I put in the pilot's stick and seat in order to adjust the neutral stick position. Man, these seats are comfortable as heck.

Here's me doing ergonomics testing. I was in and out of the fuselage a half dozen times before I got it the neutral point adjusted where it fell easily to hand. The pushrod has a little more than the minimum required thread engagement, which is good. If you're reading this and you haven't fabricated your F-789 yet, do yourself a favor and make it about 1/4" longer than what the plans call for.

Yes, I made airplane noises:

Posted in Elevators, Fuselage

Made rudder stops

September 3rd, 2006

If I worked at a real airplane factory, I'd get fired for taking like eight hours of work over two days to make these stupid little rudder stops. Of course it doesn't help that the design requires each set of stops to be tailor-made to the individual aircraft. I spent a huge amount of time measuring, making and discarding test pieces, and fiddling around with templates. Out of absentmindedness or frustration I forgot to take any photos of this process, so here's a shot of the first rudder stop I was able to produce that actually fit:

You can see that I've temporarily installed the rudder cables to make sure that the rudder stops and cables don't get tangled up at any point along the full swing of the rudder.

Here's an overexposed overhead view showing the angle the rudder horn is at when it hits the stop. Lots of cutting and filing to get to this point.

It means nothing unless it has that swing – when the rudder hits the stop and the elevators are neutral, it's just a shade over an inch from the rudder to the inboard corner of the elevator trailing edge. Plenty of clearance to keep the tail surfaces from banging together, and slightly more travel than is called for in the plans. Extra rudder travel is good, it means extra rudder authority. I've heard of some people making this dimension more like 1/2", but that seems like cutting it bit fine to me.

After I was finally satisfied with the fit, I rounded off all the corners and made the stops look pretty, and countersunk the rivet holes. These two I was able to do with the countersink cage; for the two that are closer to the flange, I used this setup to make the countersinks freehand.

I primed the stops and the skin underneath, then riveted them halfway on. The plans call for CS4-4 blind rivets in the front two holes. I used CherryMax CR3212-4-4's instead since I have a whole drawerful; the literature says they are something like 3x stronger in shear. The aft two holes will have to wait for now, since I can't squeeze those rivets until I remove the vertical stabilizer.

This photo is to remind me that I haven't torqued any of the control surface jam nuts yet – my torque wrench has a 1/4" drive and my crow's foot wrenches take a 3/8". Time to go to Sears!

Posted in Fuselage, Rudder

Hung the rudder

August 27th, 2006

I didn't work much on the plane today, but I did get the rudder hung on the vertical stabilizer. It swings without any binding at all, which I suppose means that everything is straight. I'm not completely sure that I have the two hinge lines parallel, so I will probably remove and tweak it a few times before I torque the jam nuts.

Holy cow, the tail is getting huge!

Since the rudder stops aren't in place yet, I jammed a couple pieces of foam rubber beteween the rudder and the vertical stabilizer spar, to keep the rudder from swinging too far and getting banged up.

Posted in Rudder

Finished second rudder

August 26th, 2006

I took my replacement rudder over to John's place in order to make use of the five foot long back rivet plate he made. It made riveting the trailing edge pretty easy. First I set the rivets partway with the back rivet set, then flipped the rudder over and finished them off using the mushroom set.

Here's another one of those photos that shows I really built the airplane. Also that I shill for the Boulevard corporation on laundry day.

I alternated the rivet directions because I'm anal like that.

Then while we had everything set up, Chad and John finished off the trailing edge of John's rudder:

Two rudders completed!

After I brought the rudder home, I set about rolling the leading edge:

Done! I'm happy with the rudder now. Whew. The very long back rivet plate is an excellent way to do it, at a total cost of about $24 worth of steel angle and machine shop work.

Posted in Rudder

Worked on seats

August 26th, 2006

This morning I fitted the required hinges to the new seats:

Really astute observers may notice that the hinge arrangement with the Classic Aero Aviator seats is different from the stock Van's seat backs. These seats are actually interchangeable between left and right, where the stock seats will only fit onto the floor hinges one way. Don't worry, I measured multiple times and this really is how it's supposed to go in order to center the seats on the control sticks.

Then I drove out to the other side of the KC metro to go to the Grain Valley (3GV) fly-in. Here's a photo of RV-9A builders John and Martha checking out a possible paint job:

Posted in Fuselage

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