Stjohn's RV-7

6 hours.

No, it’s never finished.   Today I took the seat wedges that Shelley made out to the hangar and installed them.  They boost my skinny arse up enough to see over the nose when taxiing, and put me in the same position I had when I finally figured out how to land Mike Seager’s RV-7.

I spent a bunch of time finessing the alarm and limit settings on the EFIS, then chatted with Jim D for a bit about his first flight, what to do, and what to expect.  Since I’d just set a bunch of things, I wanted to check it out, so I took the plane out for a little spin.

Everybody says “don’t do high speed taxi tests, they’re not necessary and they’re not worth the risk.”   I would normally agree with that sentiment, but I had a good reason: I wanted to make sure my prop wasn’t going to overspeed when I rammed it to the boards on takeoff.   I suppose I could have just pulled the prop pitch back if that had happened, but I really don’t want to deal with that in addition to everything else I’m going to be doing when I do the first flight.

I did a proper runup, because there’s no reason not to, and if the taxi test inadvertently became a first flight, it would be good if all the stuff works.   Called the tower, asked for a high speed taxi, waited for a 172 to land and get off the track, then I went.   RPM’s peaked out at about 2650, which is about right, so that’s good to go.  I braked  and got off at the first intersection, no problem.

After that, I got back into the EFIS and messed around with the moving map settings and autopilot setup.   Not that I’ll be screwing around with the autopilot or using the map a whole lot, but I did find out one important thing:  my autopilot servo was set to go the wrong way.   That means that if I turned the heading bug to the left, the autopilot would make the plane go to the right, which is really counterproductive.   So I fixed that.  Easy enough.

So now I just have to wait for a good day to fly it.

7 hours.

313TD is now ready to fly.   It is legal, insured, fueled and ready.  If I didn’t have a mountain of work to do at work, I could go up there, push the airplane out into the open, fire it up, and take off.

It’s not finished.  Don’t get confused on that: Wheel pants and gear leg fairings still have to be done, and I’m still working out the engineering particulars on that one, because I have to suspend the aircraft in such a way that the weight is off the wheels to align the fairings.   Otherwise they act like little rudders, pointing the plane in an off-track direction.   This means you have to fight it with rudder input, and that means you lose efficiency because your airplane is essentially trying to fly sideways.

Efficiency is important.   Yesterday, I bought 22 gallons of aviation gasoline at $6.06 a gallon.  Ouch.   The reason for buying this gasoline is in preparation for the first flight, and also to calibrate the fuel level sensors in the wing tanks.   Each tank holds 21 gallons for a total of 42, so the plan was to do one tank at a time.

Our local Oxnard EAA chapter, which consists of the 8 guys who can reliably show up on the last saturday of every month and take care of business, has access to the really cool hand cranked fuel cart, which pumps both forwards and backwards and measures the amount of fuel pumped in either direction.

I called the Jet Center and had them put 22 gallons in the cart,  Which I could then use to increase the level in each tank according to the calibration “marks” on the EFIS.  If I recall correctly, these are 0.1, 4.6, 8.3, 12.5, 16.7, and 21.0 gallons.    The sensor is attached to a float inside the tank connected to a rheostat, and the numbers it puts out are simple resistance values read by the EFIS.   So with each amount pumped in, the settings menu gets the resistance value entered at that amount.   Simple.   I’m not sure how dead-on-balls accurate it is, but my initial test with the pump put 5 gallons into a 5 gallon gas can, so that was probably good enough.   I’m also not sure how much fuel it took to prime the pump and fill the filter chamber, but I’d put it at roughly half a gallon.   That’s OK, I drained about 2 and a half gallons from the aircraft tanks into a 5 gallon can before I started.

Also, this process needs to be done with the airplane in level attitude, because that’s when your fuel level actually matters.  Once again, Ron’s old lift was the solution for lifting the tailwheel.   The process was to pump 21 gallons into one of the tanks, set the levels, then pump it back into the fuel cart to verify the settings.    This also involved draining the current tank after the pump had sucked all the fuel out of the section where the fuel cap is, because even after pumping out all the fuel, there’s still 4 gallons left in the tank.   Also, when the pump runs dry, it still moves the counter.   Did I mention this thing is hand cranked? Yeah.  I’m sore.  Anyway, I repeated this process twice on each tank and the numbers were within .2 gallons each time, so the pump and the sensors appear to be doing the right thing.

So that’s done.   I’m ready to scramble.   All I need now is a day with good weather and relatively little outside stress, and we’re going up.

7 hours.

With the airworthiness inspection in the rear-view mirror, the next phase of this little adventure starts in earnest.   Of course, “airworthy” is kind of a misnomer.   It’s not airworthy until all the parts I took off for the inspection are back on.   That’s all the inspection panels, wing root fairings, floor panels, and interior.

When Dave and i measured the down angle of the flaps, we got one at 47 degrees and one at 49.   They’re supposed to be at 45, so that was first on my list to fix, but I measured them from the bottom side instead of the top and they both dialed out at 45.   Go figure.   After that, it was on to the interor panels.   I put the baggage bulkhead back in, flap actuator covers, then baggage carpet, bulkhead cover, and side panels.

After that it was the floor panels, with their multitudes of velcro discs designed to hold the carpet steady.   Then the front spar covers, and the tunnel cover.   This got interesting, because there are two holes in the firewall with platenuts that have nothing in them.   I can’t get the AN4 bolt in one of them and the other has a slightly off-center hole, so the bolt won’t seat in the threads of the platenut.   Bah.  Argh.   So I made the decision to put them in from the firewall side, which I’ll do later.

Then the fuel pump cover, with the newly attached fire extinguisher went in.   After that, I put in the carpeting, side panels, and stick boot covers.   It now looks like a proper airplane, and I could fly it, except for one thing:   The roll trim is wired backwards.

Yeah, I know, aren’t you supposed to be “ready for flight” when you call for the inspection?   Well, he didn’t make me fire up anything electrical, so I wouldn’t have caught this, because when I checked the trim motor, I saw the little arm on the trim servo move to the right when I toggled the right side of the 4-way on the stick.   Toggle the left side, the arm goes toward the left.   My brain failed to register that the arm is connected to wires attached to the bottom of the sticks, on the other end of the pivot point, so the arm is actually the reverse of the direction the sticks are moved in flight.

As soon as I realized this, all I could hear was Gunnery Sergeant Hartman in Full Metal Jacket:   “What side was that, Private Pyle?”

This, of course, is after I’d screwed down the fifty or so floor panel screws and installed the carpets and seating.   I figured it might be fun to sit in the airplane and get comfortable with the final UI of my airplane and practice things like getting the fire extinguisher out of its bracket, reaching fuses, finding the most comfortable rest spots for my elbow, that sort of thing.  So imagine my disappointment when I realized I’d have to pull the seat cushions, carpeting, and floor panels to switch the trim wires.

That’s a project for this weekend.   I also need to finish the cowl hinge pins, plug the aforementioned firewall holes, blob a little more RTV into the seams between the baffles and the engine, and do some taxi tests.   I know it taxis, I just want to see if I can get the under-cowl temps down a little more.

5 hours.

I took my freshly painted spinner and cowl up to the airport to see how it would look. Not bad. Beats pink and purple, that’s for sure.

Of course I forgot my hinge pins for the cowl, so I’ll have to bring them up next weekend.   But as part of the exercise of rolling the plane out to shoot these pics, i spent some time running the battery down, playing with the EFIS.   Also, Derek Spears stopped by in his Cardinal.    He gave me the quick tour of the GNS430, which is truly an amazing piece of hardware that I don’t know how to use just yet.  He walked me through the major modes and flight planning, and I was able to get the EFIS to pick up flight plans, nav info, and waypoints from the ARINC 429 feed from the 430.   Derek programmed in a flight from OXR to SMO using Van Nuys and Burbank as waypoints.  The EFIS displayed the legs as HITS boxes as well as a moving-map track.

Also, I confirmed that the nav antenna in the wingtip does work; I was able to pick up the Ventura VOR on 108.20 and feed the EFIS’s HSI with it.   One thing that bugs me a little;  In order to get VOR navigation stuff to show up on the EFIS screen, I need to be in External Nav Source mode, which means the EFIS doesn’t use its internal GPS.   This is ordinarily OK, but there have been issues driving autopilots using the 430 as a GPS source.   Something about the resolution and the frame rate that makes the autopilot hunt for headings, or something like that.

Also, of interest: The EFIS isn’t a big fan of low system voltage.   Piddling about with the equipment for as long as we did really ran the battery down, and when that happens, the EFIS does things like spontaneously reboot when changing screens.   This is not good.

So on  my to-do list is to sort out the backup battery and how to preserve EFIS functionality during all modes, including engine start.

Confirmed that the passenger headset jacks work, after fumbling with the audio panel for a bit.

After Derek left, I went flying in Don’s RV6A for an hour, then came back and did some more safety-wiring, and used my newly purchased Weld-On #4 to try to bond the small crack in my canopy.

I also set up the EFIS with all the V-speeds for the RV-7.

3.5 hours.

Today’s big story was attaching the N number.

Behold my legalness.

And yay, more legalness.  This gets covered up with masking tape until it’s airworthy.  No sense giving the tax man a foot in the door before it’s necessary.

After this, I went for a quick flight with Don in his RV6A.   Don’s between medicals at the moment, and I’m in need of RV hours, so we both get to fly if we’re both at the airport at the same time.  Today I flew us over to Santa Paula to get some fuel.  Apparently, I don’t suck at flying the 6A.  But today was an optimum day for flying, with clear skies and smooth air, so that helped.

After that, I replaced the silicone fuel line I was using for the fuel pump overflow connector and replaced it with some real 5/16″ tubing and secured it with hose clamps.   Then I dismounted the spinner and empennage fairing so I could bring them home to paint them.  Or at least shoot a half-assed covering of primer on them.

I’m getting tired of the pink cowl and the purple spinner, so even though it might be kind of a pain to deal with later, I decided to spray the cowl down with Krylon Olive, which is pretty close to the same color as the dropship in James Cameron’s “Aliens.”  It’s flat.  It’s easy.   And when I get around to spending a hundred hours or so touching up and filling in the cowl, maybe I’ll do something different.   Or it’ll go to the paint shop and it’ll be somebody else’s problem.

The result you see here is before the paint’s actually dry, which accounts for some of the streaks.  But when it’s done it’ll be a nice, uniform olive drab.

Maybe I’ll do the spinner bright red.  Or black with a twisting white stripe.  Although, the metallic purple actually looks good with this color green, so maybe I’ll leave it as is.

1.0 hours.

I almost forgot.   Yesterday I had to lift the tail to make the plane level again, because I forgot to do a couple of crucial measurements.

Without going into great detail on what weight and balance is and how it’s calculated, just understand that all the center-of-gravity or CG calculations are done based on distance from a fixed point in space, called the datum.  Yeah, it’s the singular form of ‘data’ but you knew that.  Moving on.

The datum for the RV7 is established by the designers at 70.00 inches forward of the leading edge of the wing in level attitude.    Distance from the datum is measured at a couple of places, like the center of the main wheels and tail wheel, and other distances are given, like the passenger position and the baggage position.   Those distances are called “arms” and when multiplied by the weights at the wheels gives “moments” in inch pounds.   This lets you do all sorts of interesting things like figure out how much that diet of cheeseburgers and Budweiser  is preventing you from taking off with more than half-tanks of fuel and a pair of silk briefs in a tube for baggage.

To get these measurements, I took a couple of plumb bobs and hung them over the leading edge of each wing near the wheel centers.   That distance +70 was the arm at the main gear.   Another couple of plumb bobs got me what I needed at the tailwheel.

So now I have all the relevant weight and measurements to work up my weight and balance sheets.