Fuselage Construction
Fuselage Construction |
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Date: 10 June 2002 - 16 June 2002 |
Chapter: 10.0 Fuselage |
Section: Fuselage |
This section has general information about the keel and it's access points.
Control Stick Access Holes
The keel has been fitted against the canard bulkhead that was installed by the factory, however. Also, we drilled 1/8" holes in the aft section of the keel to access the torque tube bolts on the rear support.
26 July, 2002 - Now that we've set the location of the speed brake actuator, we've cut a 6' diameter access hole just ahead of the section of the keel reinforced by foam to get at the actuator and it's electrics.
Brake Actuator Access Hole
This section was competed by the factory.
The first hard point we made on the Keel is this "house" shaped one on the pilot's side for front control rod bracket. It's 5-3/4" at the peak with a 5" tall by 5.5" wide. It's is attached on the inside of the keel with micro, with a small fillet or sand the edges (we sanded the edges smooth), and covered with four plies of bid. The remaining keel hard points (on the fore bottom pilot side) are preinstalled on the quick build fuselage.
The seat hard-points were installed using the factory placement guidelines as a starting point, however our seats have a large amount of side-bolstering, so we mounted them slightly off-center, but the specified 35" from the canard bulkhead. The rear seats were trial fitted in different locations, to allow for different operational characteristics. We tried allowing space behind the seats sufficient to fit a suitcase, as well as complete aft for maximum leg room. Since we will be making the over-sump ledge/cover panel with extra support structure to allow for luggage storage on top of it, we elected to give the rear seat passengers as much leg room as possible. Also, when we have 4 passengers, we won't have a lot of excess weight-carrying capacity for luggage anyway, and when we fly with fewer passengers, we can stow baggage in front of the rear seats.
Hollowing out the outer seat hard-points
Hard-points Installed
In this section we drilled the holes on either side of the keel for the control stick bolt in the pre-marked positions.
However, it is a lesson in what not to do. Of course everyone has heard the sage advice to buy a copy of "Acceptable Methods" (AC 43.13-1B http://www.tvbf.org/docs/ac43/), and I had even bought my copy. However, I had not read my copy when we attended Head Start. Of particular note is the section on Bolts. Lots of good information on how much grip to have, how many threads to allow to stick out, how not to have any thread under a rotating shaft, and how important bolt hole tolerance is. I initially made my bolt holes way too big, so I'm remaking my actuator brackets.
Flash! New brackets have been made, and we've tested the fit. Not good news here, sports fans. If you're playing along at home, you'll find that the IN NO PLACE in the keel is the full retracted speed brake actuator long enough to just close the brake door. The manual states that this is preferable, and it's obvious, the actuator comes with no means to shut off prior to reaching it max travel, so it hits the stops it pulls your screws out or breaks something (really, trust me on this one friends). Seeing as I didn't want a limit switch to have to shut this thing off when it reached the fuselage that would just break (then break the brake....) and I didn't want to lose precious brake travel to this shortfall, I went the other route and built a wood brace for the actuator to mount the keel with that would just fit perfectly. I did worry about this situation, however, I will admit, so I called Frank at the factory. As it turns out this is exactly how he does it with one difference, he makes the brace a little short and shims it down with washers in case he needs extra travel later. That seemed like extra work now when I could that work down the road, and only if needed, so I omitted that step. I did however have to order longer screws from Spruce to hold the bracket.... Very cool, though, watching your brake go up and down making real, honest-to-goodness plane sounds.
In this section we mounted the front aileron control torque tube support bracket on the inside of the keel, pilot side, with the flange facing forward. The front end of the bearing goes 18-1/4" aft of the front flange of the keel, over top of the the "house" hard point we put in in Section 10.1.5, 12-1/2" above the bottom keel flange. Three bolts attached this to the hard point, though we let it hang free on one until the aft end was located in the "whale tail" to get the angle right.
"House" Keel Hard Point & Control Bracket
In this section we mounted the front aileron control torque tube support bracket on the inside of the keel, centered in the whale tail, but down about 5/8" (this measurement isn't really that critical for Fixed Gear aircraft). We also mounted the Roll Trim motor through the whale tail, and the control bracket to the whale tail. However, we later decided to convert to a different system. Here's the factory roll trim setup.
Aileron Control Bracket & Bell Crank
Roll Trim Motor on Whale Tail
We, however, wanted to get more assured trim movement (we'd heard from several builders that the string/motor setup provided by the factory was prone to slippage), as well as indication. To do this, we selected a 1.2" Ray Allen electric servo, which has built in indication of travel/position. This required a fair amount of modification. The whale tail had to be trimed to allow the servo to fit through, and to allow the servo arm to fully extend. We also had to create a sliding bar that would hold the trim springs while the servo moved. This way, the trim system does not move the flight controls, it merely adds or removes pressure from the control stick, acting through the springs. This bracket then had to be connected to the servo through a slot that we machined in the factory torque tube bearing support. The servo comes in two pieces, the servo and the relay deck, and to facilitate easy installation and removal, we installed each unit with DB9 computer style connectors.
Planning the Roll Trim Conversion
Connecting the Roll Trim System
Permanently Mounting the Whale Tail
Computer Connector Wiring (DB series)
In this section we mounted the aileron control torque tube mid-bearing support bracket on the inside of the keel, along the pre-marked line on the keel. With the rear bearing support located, we measured where the torque tube lined up inside the keel and located the 1" hole on the support rib. We then sanded the keel in this location and attached the rib with structural adhesive and rivets, and the bearing was installed with microglass. With everything aligned, the remaining bolt holes were drilled and the hardware installed.
In this section we installed the control stick onto aileron control torque tube. On this piece, it's important to note that due to the saddle connection, there is only one proper way for it to get installed, and that the outside end is treaded to accept the bolt so no nut is required.
Aileron Torque Tube Assembly
Control Stick Mounted on Aileron Torque Tube
Also installed in this section was the bell crank pictured above, with it's line and spring system. It's also important to note here that all of the bolts were installed so that would normally be pointed straight down. This is in case the nut were to ever depart the connection, the force of gravity would naturally tend to hold the bolt in place. Also note that the springs in my picture aren't under enough tension yet. Here is a picture of the completed assembly, with the push-pull cables for the ailerons attached, and the tension set properly (note that the right side is held up off of the bracket by a stand-off that keeps it inline with it's attachment point on the aft side of the bellcrank).
Aileron Bell Crank with Push-Pull Cables
Once the control assembly was installed we permanently installed the keel with structural adhesive and rivets. The manual recommends also installing the speed brake mounting channel to the keel prior to permanently affixing it, and I would recommend this in hindsight, but this is the way Frank recommended it during Head Start. Also installed in the keel is 26" of biaxial tape.
Keel Interior Reinforcement
Then the forward side of the canard bulkhead gets bid tape.
Reinforcing the Fore Side of the Canard Bulkhead
Once the keel is installed, you need to do series of stiffening lay-ups with Tri-axial cloth. There are four inside the keel, one runs along the floor and up onto the canard bulkhead (3 plies of 5"x18", running 10" onto the bulkhead), one left to right (2 plies of 10"x13" with the 10" side running up and down), another left to right (4 plies of 4"x13" with the 4" side up and down), and another for and aft along the inner keel sides (7 plies of 2"x2"). We completed these during Head Start, the inside reinforcing can be seen in Section 10.3.5 above, the exterior reinforcing is below.
Keel Exterior Reinforcing
These are now pre-molded at the factory.
These are now pre-molded at the factory. We've cut the 5/8" lip for the flange onto the fuselage, and sanded the door to fit. We have done some finishing work with Cabosil, filling the void between the hatch and the flange. This is accomplished by duct taping the cover and the pressing it down into the Cabosil and weighting it down until the Cabo cures.
Also, the manual says to install 4 screws to hold this down, but we're considering options that would not have screw heads showing.
Nose Hatch Cover Rough Fit
Nose Cover Finishing
Here we've finally worked out a set of hinges that will allow the proper opening of the nose hatch. I was struggling to get the geometry of this right, so I fell back to plan B, I asked a girl. OK, not just any girl, a Cozy Girl. They have all sorts of really good ideas, and had already solved this one for their plane, so I got some great CAD drawings and tips from them, from which it was a simple task to finish up these snazzy hinges. Then I installed the factory latch, and a T-handle release mechanism.
Forming the Hinge Bases
Jigging the Hinges in Place
Hinges Bondoed into place to test operation
Hinge in place for Testing
Tada!
Well, would you look at that?
Factory Latch - very swank
Yup, that's where it needs to mount!
'Hood Latch' Handle
OK, here's the deal on Master Cylinders, and real no holds barred data dump. Very important, shouldn't be a big deal. The only thing is this the modification mentioned below in 10.5.3, where we pulled the pedal mounts to the very outside of the pedal cross tube, which pretty much centers the pedals. That's all good, but if you follow the plans they have you center the pedals on the bump in the canard bulkhead, which seems to put them just left of center of the pilot side seating "space". Anyway, to make a long story short, where our hit is the slanted section of the bump out, so I had to build that up flat with schmooy, BID over it, and then after drilling the holes to match the master cylinders order longer bolts for the right brake. Did I mention the big fun I'm having building this plane? ;-)
Anyway, with that done, I bolted them to the bulkhead, and attached the push blocks to the push rod, and we ready to go.
Building up the Pedestal with Glass Bubbles
Covering the Schmooy with BID Cloth
Mounting the Master Cylinders
Next, we've decided that we'd like have a parking brake, so that we can get out of the airplane without worrying about it rolling before we set chocks under it. We've purchased a Matco parking brake to handle this duty. We've mounted it just under the panel on the pilot side wall. Correction, after fiddling with the panel and things, we've mounted it to the bracket in the below picture (for the EFIS box) so that a control handle could be fabricated (by my builder buddy Jerry Brainard) and installed.
Parking Brake mounted, Waiting for Plumbing
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Parking Brake Control
Assembling the rudder pedals is a pretty straightforward exercise in connect-the-dots. Of note is the fact that the back of the pedal has an arm that actuates the brake on one side of the plane for steering on the ground (the nose wheel is freely castering). We've decided to install a set of Sparco racing pedals onto the standard Velocity "pedals" which are just tube aluminum, and the paint the pedal assembly.
Pedals Installed on Brake Pedal Tube
Again, mounting the brake pedals is pretty simple. It is worth pointing out, though, the idea that Frank gave us of making sure that the pedal mounting blocks are far enough to the outside of the assembly that is no play in it. It is mounted with a slight gap above the keel. This is pretty well shown in the pictures above. Finally the brake lines are run down the pilot side conduit to the 1" openings just ahead of the firewall and down to each brake. The lengths given in the manual for these runs I found to be just a bit short, so I had to recut them. Also, the gear leg openings were so tightly fitted at the factory I drilled holes through the fuselage just above the gear leg to make sure the gear didn't pinch it on a rough landing. The tubing was then glassed into place.
Co-Pilot Brake Line
Glassing Brake Lines
10 October - Retrofit. The new factory instructions for the brake lines includes running the brake tubing inside of straws which act as a conduit. Here is a picture of my retrofitted installation where I've also made the fuselage hole slightly larger and installed a grommet, micro-glassed the straw, and covered it with BID.
Not sure where this should go, so I'm putting it here. When I first bled the brakes, I was told, "yea, just get a pressure bleeder and force the fluid up from the brakes slowly, it'll be fine. I tried that, no luck. Got a vacuum bleed, and mounted it to the master cylinders in the nose. No luck. I tried the two together. Rinse, Repeat. No luck, still squishy, still air bubbles trapped. Much slippery DOT 5 spilled on floor, much nashing of teeth. Now, I'd always heard that if you lifted the nose up and let it sit like that for awhile, it would work much better. I was always leery of that, fearing that she'd sit back on the motor and bust something. But, I broke down and tried it, because, hey, I need brakes. Turns out, she's pretty stable when lifted (at least with the wings off), and so I let it sit overnight. Guess what? Next day, I pump the brakes once each (note, no bleeder at all, just a light pumping action), and presto, a big bubble, and then great firmness on the pedals. And the clouds did part, and the Lord spoketh to the his bleeders, "be thyne at your ease".... Gravity truly is reliable.
Gravity Bleeding
This section is simple enough, just take 3/16" nylaflow tubing from 6" aft of the attachment point on the pedal assembly, through the carbon beam, sweeping gently up to the top of the gear bulkhead and extending slightly out the back of the firewall. The only real trick here is that the recommended method of taping this line down didn't work too well for me while the small sections of BID were setting up and I had to try all manner of weights and things to hold them in place.
Left Rudder Conduit
The panel location was set as part of the fast build fuselage.
The panel attachment brackets were laid up as part of the fast build fuselage. The screw and nut plate were not installed, but we will hold onto this to see if we use the factory panel or not (we're considering a carbon fiber panel).
We have installed the factory panel in the expectation that we will cover this in carbon fiber later. If we chose to do a custom panel later, we will need to redo the tabs and nutplates (8 of which were riveted to the 3 panel attachment tabs).
Mounting the Instrument Panel
During Head Start week we fitted the canard. First we leveled the plane, and then progressively sanded underneath the canard until it just rested on the canard bulkhead, the we checked it's incidence. Once the incidence was right we pilot drilled for the lift tab bolts. This section recommends trimming the elevators to fit the fuselage contour, which we as part of Chapter 15.1.3.
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