Today was a day with lots of hours and not a lot of pictures. I finished the work on the left air intake, which included dimpling the boot cowl and cutting countersinks into the plastic vent. I also dimpled all of the holes in the boot cowl skins that will get rivets, except for the firewall flange. I wanted to wait to commit to fasteners on the firewall flange until cowl time. I added some missing nutplates to the glareshield hatch (the corners that needed single lug nutplates) and started adding the nutplates to the lower boot cowl panels.
Here's a nice row of nutplates (in the wrong place)
Above you can see that I put the nutplates on wrong. I have made this panel 3 times now, so hopefully it is correct (speaking from the future again).
I also cut off some long strips of aluminum to use for the wingtips, and started preparing the stainless tunnel piece for it’s nutplates. It is so thin that dimpling is the only option for the nutplate rivets.
Thanks for Visiting! • This Entry is from June 4, 2010 at 11:00 pm
I’ve been watching the price of the engine mount rubbers for the past few months, and the trend seems alarming. In the 2008 Vans Accessory catalog, they were $40 per lug (for a total of $160). Today Vans sells them for $125 per lug, or $500 plus shipping! Yikes! I was surprised to see the cost go up so quickly. I was looking for some way to spend less, and eventually found that Jeppesen of all places sold them. Their price was well below anything else that I could find, at $88 per lug. My only explanation for this was that their price was outdated, but who knows. I was glad to save so much money. Here’s the data from the box:
Lord J-7402-24 Engine Mounts
Nobody seems to know how long the bolts need to be for attaching the mounts to the engine. I don’t really understand the mystery- the mounts have a center tube that gets compressed to the washers on either side. Now that I have them on hand I can measure the length of that tube and the end washers to come up with a grip length for the bolts. Here are some pictures of my measurements, in case you find yourself wondering how long the bolts should be.
This was just the uncompressed length, not very useful.
Here's the thickness of the end washer. It's just a little bit more than .1 inch
Here's another somewhat useless measurement- the uncompressed gap between the two big pieces.
Here's the uncompressed length of the pair
Here's a much more useful measurement- the thickness of the assembly once it is compressed.
This is the measurement that I took of the thickness of the engine mounting ear on the engine. This one isn't especially accurate, but is pretty close.
For the purpose of ordering bolts, my measurements aren’t especially accurate, since the bolts generally come in 1/16″ increments. I figured that the compressed rubber was 2.03″ and the engine lug was .93″. This makes the required grip length for the -7 bolts 2.96, not counting for any washers (and I’ll need at least one of those at 1/16″). The AN7-34 is 2 15/16″ (2.9375″), so I ordered the 7-35 with it’s 3 1/16″ grip length. That will allow for a washer or two but will keep the bolt’s threads out of the way.
With that bit of research done, I started working on the air intakes that will go on the sides of the boot cowl. These will provide fresh air for the front seats through an eyeball wemac type of vent on the instrument panel. I got the scoops from Vans, their part SV-1 at $6.25 each.
Here's one of the scoops from Vans, along with a cardboard template that I made for marking the aluminum skin.
I wanted to make an aluminum backup ring so that the plastic part would be sandwiched between two layers of aluminum. The cardboard template made that step easy.
Here are the two rings and a nice view of the back of the SV-1
I drew a few lines on the boot cowl to try and figure out where I wanted to put the vent. My primary goals were to make the centerline of the intake horizontal in level flight, and to keep the intake lower than the outlet inside, so that water would be more likely to drain out if we were flying in the rain. I’m curious to see if this works.
Here's the mark on the boot cowl sheet for where the vent will go. I almost oriented the vent backwards! This is the right side of the airplane, with the nose facing right.
Here's a more wide-angle view of where the vent will go.
Here's the boot cowl skin flattened out and ready for cutting the hole.
Now I just need to dimple the skin, countersink the plastic, and put everything aside until I'm ready to permanently attach the intake.
I got to the point of dimpling the holes for the first side and had to quit for the day.
Thanks for Visiting! • This Entry is from June 3, 2010 at 5:30 pm
I started out today by finishing something from last week.
This is the forward attachment for the top stringer, looking up and slightly forward.
While I had the torch out, I also added a few more parts to the skylight area. First up were some plates for the headset jacks.
This plate will hold the headset jacks for the front and rear set occupant on one side.
This plate goes on the spanwise mini-bulkhead that I’m creating at the aft side of the skylight. This is what it looks like with a couple of the jacks installed temporarily.
The switch is required to specify stereo or mono headsets. I've never seen an intercom that required such a switch.
The holes started out as small pilot holes, as you can see in this left-right before and after picture.
Here it is after welding in place
This location will put the headset plugs and cords up and out of the way, behind the front seat passengers and ahead of the back seat passengers.
Thanks for Visiting! • This Entry is from May 28, 2010 at 1:45 pm
Today was a two-part day. In the first session, I used a dremel tool to remove the weld on the vertical portion of the door threshold at the forward end. This was to allow for repositioning that piece so that it would attach properly to the aluminum piece that goes there. This also involved cutting loose the piece that I added on earlier.
This is the forward lower corner of the front door. I've removed the weld and the paint in the area so that I can bend the whole vertical piece out some.
This is the same piece that I added earlier in the year. This time I trimmed it and moved it inboard some to allow for the aluminum panel.
I also addressed a small scratch that I made on one of the engine mount tubes. I sanded the area with fine sandpaper to remove the scratch, then sprayed a little bit of temporary primer to keep it from rusting.
Engine Mount Touch Up
In the second session I added on the front tubes for the skylight, cut the chordwise tubes loose, bent them to a slight curve, raised the front piece up, and cut out some new stringer tabs. This is all work that I wrote about a few entries back.
Thanks for Visiting! • This Entry is from May 20, 2010 at 8:45 pm
Today Tabitha came out again to finish squeezing some more wingtip rivets. We also tested the glue on the foams to make sure that it wasn’t going to dissolve them. The glue checked out OK, so we glued one of the bottom cushion combinations. Tabitha marked it for cutting and spent some time thinking about how all of that needed to be done.
Tabitha is trying out a few different seat foam combinations and marking them to cut.
While she was doing all of that I worked on more nutplates in the boot cowl/fuselage area. Danny stopped by, and he and I installed the engine mount.
Thanks for Visiting! • This Entry is from May 15, 2010 at 7:15 pm
Today was a short day, but I was able to spend some time on the nutplates that will hold on the “optional” aluminum panel under the door. I learned about a few complications.
This is a hole for the nutplate that will hold on the aluminum panel under the door.
First, the nutplates won’t work well on the top unless I bend out the steel piece at the bottom of the door. The surface of the panel and the surface of the nutplate’s support have to be parallel. As it is, the steel piece is bent inward to help keep it from chaffing the fabric.
The second problem is that I have way too many holes in that panel! I’m going to spread them out a little on the top, and the door sill plate will help hide the unused holes (and share the used holes).
Here's a test flush #8 screw.
Thanks for Visiting! • This Entry is from May 10, 2010 at 4:45 pm
Tabitha came out today too and we made some good progress. I was at a stopping point with the tailwheel spring because I didn’t have a drill that would handle larger bits. It had a temporary bolt in place of the AN-7 that is supposed to go in there. With the new drill I was able to get the hole up to size and reinstall the tailwheel spring.
I got this new drill so that I could use larger bits. All of my others have a 3/8\
Meanwhile, Tabitha was dimpling and squeezing the rivets for the wingtip flush mount strip.
Tabitha was dimpling and squeezing.
I also spent some time getting ready to install the engine mount, now that I have the hardware.
Thanks for Visiting! • This Entry is from May 9, 2010 at 6:42 pm
asting complete on 1, elt brscket on, control sticks done, cast 2, cover front seat bottoms and backs 1800 lunch?
With one aileron balance tube done, the second was easy. I’ll elaborate more on the process this time.
Here's the finished weight of the first lead tube. I will be able to drill some of the lead out once the aileron is covered to get a perfect balance.
I used a thick aluminum pan that Tabitha found at the thrift store, complete with a little pour spout. It was really perfect for pouring the lead.
I used tire weights that were really dirty. I would tilt the pan, and direct the torch at a tire weight. It was amazing to watch the bright silver liquid run out and leave the dirt, oxidation, and steel clip behind. A few passes with the torch helped be sure that all of the good lead was out. From there I would reach in and remove the nasties with needle nose pliers, putting them into a nearby rotel can. I would repeat this process until I had a fairly large puddle of bright lead, then I would reheat that puddle so that the whole thing was molten, and pour it into the tube. I would try to preheat the aluminum tube some too, in hopes that the lead would make it all the way to the bottom. Once the whole thing was cool and finished, I flipped it over and heated the other end. This caused all of the dirt and gravel to float up to the top, so I removed each of those with pliers. That left me with about a 1/4″ lip of aluminum as the lead settled into places that used to have little bits of rock in them.
I used a hammer to shrink the edge of the aluminum tube, so that it will help hold the lead in place more securely.
This would have been especially tidy if the whole tube was full, since then I could have the extra lead security on both ends.
Danny was telling me about an oil cooler that he didn’t use during his RV construction. Bob and others seem to think that it is adequate, and the price is great, so I think I’ll use it.
Oil Cooler donated by Danny
The control sticks are ready to repaint:
Here's the cap on top of the control stick, to support the push to talk.
I used the grinder to remove most of the weld bead around the control stick cap. This is to make sure that the grip will fit over the end, and this is certainly a non-structural piece, so I wasn't worried about removing the material.
I also finished the ELT bracket, except for cleaning and painting.
Here's the top of the ELT bracket, ready to weld to the bottom.
Here's the finished ELT bracket, ready to clean up and paint.
Today was a great productive day, and the weather was nice, so I figured I’d try a little bit of covering. I’m making the seat pans out of polyfiber covering, the same stuff as the exterior of the fuselage. The seats will be different from the airframe in that they won’t have any reinforcing tapes, UV protection, or color finishes.
I copied this idea from Oshkosh. The little cardboard disk helps reduce evaporation and drips.
Here's one of the front seat bottoms with the fabric on.
Today I finished covering the front seats, except for shrinking. I wanted to make this a priority so that I could get the seats ready for upholstery, which also involves cutting the foam cushions.
Thanks for Visiting! • This Entry is from April 23, 2010 at 6:00 pm
It’s been a while since the last building entry, but I’ve been out of town more than usual. I just got back from Sun-N-Fun with a new list of ideas and a few new parts.
One of my SNF finds was these LED position lights. If I didn’t already have the aeroflash lights, I would have probably gone with a different setup, but since I do, I wanted to find some LEDs to replace the four incandescent bulbs. I had seen these before in the Aircraft Spruce catalog, and the guy who sells them to Spruce had a booth at the show. His price was a little better, so I got a set.
Here are the LED replacements for the position lights.
I took the cover off of the nav lights and took this picture.
Inside of the Aeroflash
This is the green LED in place
And the aft-facing white
Here's the whole assembly back together again. I replaced the green lens with a clear one, and was actually able to sell the original lens and bulbs to offset the price of the new parts.
On the red side I found that the gasket wasn’t properly installed you can see what I mean at the pointy end of the strobe insulator.
Notice how the black gasket doesn't quite fit right.
The white insulator wasn't quite right either.
When I put it all back together I put the gasket on correctly and also made sure that the white insulator was correct. I wonder if it came from the factory this way.
I realized that I should probably take some documentation pictures of the engine and accessories, because I always find myself with questions when I’m away from home.
The Starter...
...and the ignition wires...
...and the starter ring gear...
...and the carburetor...
...and the carburetor data plate...
I also found a baffle kit for sale second hand. This one wasn’t related to sun-n-fun, but I hadn’t had a chance to go through the kit to make sure that it was complete.
The plans for the Vans baffle kit are on one big sheet
There's all sorts of hardware in there
To change gears again, I finally had enough lead to fill the aileron balance tube. I ran safety wire from the corner of the bench to the tube, then leaned the tube slightly down and to the right as shown in this picture.
Aileron Balance Tube
This is a 1″ tube, which is larger than the 3/4″ tube originally designed in the plans. The diameter change is to improve the aileron if I recall correctly- it doesn’t really matter, since my ailerons have a 1″ hole in them. Back with the old 3/4″ tube, builders had to fill the entire tube with lead in order to get the required 5.5 pounds. I’m glad that another builder pointed out that the 1″ tube definitely does not need to be full. Without this tip I might have not thought about that until it was full of lead. I started to wonder if this uneven weight distribution would be a problem. I asked Bob, and he said to just leave the tube at it’s full length so that it will have more attachment points, and not worry about it. I’ll probably have to drill some of the lead out to actually balance the aileron. If I leave the 1″ hole open during covering, I will still be able to get a long drill bit into the lead. I can make small covers to pop-rivet over the 1″ holes when that is done. This will also come in handy if I need to recover the aileron later.
While I had the torch out, I figured I would also weld a cap onto each of the control sticks. This will make it much easier to mount a push to talk switch on the top. In this picture I’ve cleaned the paint off in preparation for welding.
Control Stick prior to welding
I also removed the paint for the ELT bracket
I don't remember where I got the idea for this holding fixture. It is 16 gauge copper wire and alligator clips. For tacking it works well, but since the clips are soldered it might not hold if it gets too hot.
Thanks for Visiting! • This Entry is from April 22, 2010 at 5:30 pm
Today I was in the mood for some welding. First, I noticed back when I primed the headrests that I had missed a problem with one of them. I had started to cut one of the horizontal tubes, then realized that I was cutting in the wrong place. This left a scored line around the tube, so I wanted to grind the paint off and run a bead around that score mark to remove the potential stress riser.
Fixing a problem with one headrest
Next, I needed to make a welding cart to hold my tanks. I started with this cheap harbor freight hand truck and spent an hour or so modifying it. I didn’t count this time towards Bearhawk building of course.
Starting point for a welding cart
With the tanks safely secured, I started on that ELT bracket. I started with the tube that will hold the fairlead plastic, and a short piece of tube that will locate that tube vertically.
Even with as much practice as I have, I still am not a pro. Note how I didn't get out fast enough with the torch at the edge of that thin 7/8\
My goal was to try and locate the top of the antenna plate just below the level of the stringers, just in case the covering had a little bit of sag between them. The reality is that since the stringers are so close together at that point, the covering probably won’t sag at all.
The ruler is just a straight edge to hold the bracket blank level with the stringers.
Here’s the blank after I’ve bent it. It’s going to be a tight fit with a 90 degree BNC adapter to keep the coax out of the elevator trim cable’s way.
ELT antenna bracket view from the top
Here's the top half of the bracket
Thanks for Visiting! • This Entry is from April 2, 2010 at 4:45 pm
Today I spent some time going through a big order of parts and hardware. This order included lots of stuff, including the rest of the screws for the wing inspection panels.
This is my organization method for the wing inspection panel screws. Each panel gets one compartment. Can you guess which ones are for the fuel tank panels?
Dad was in town, so he cut out some new strips of aluminum for the aft section of the rudder cable guards.
Dad deburrs the new cable guard blanks on the scotch brite wheel (which he gave me for my birthday).
I also ordered a foot of 7/8 .035 4130 to make fairleads out of.
A new fairlead tube for the ELT bracket
Here’s where the new fairlead will go, just under the new ELT antenna bracket that I haven’t made yet.
It goes here, mostly. This is the buklhead station aft of the rear cabin bulkhead.
Thanks for Visiting! • This Entry is from March 31, 2010 at 6:50 pm
Today I spent an additional 1.5 hours on the wingtip, but the more exciting news is that an order came in from Wicks.
Seat Foam and Invisible Cat
I ordered some 5052 Aluminum to make fuel lines out of, along with some foam for the seats. My plan for the seats is to use tempur foam for the bottom layer for its shock absorption, then to use regular seat foam for the rest. Wicks had the best price that I could find on a 1″ thick green cushion that was big enough for the seats.
Here our quality assurance department verifies the alloy of the aluminum fuel tubing by smell.
I also got some rivets for the doors. They are made of aluminum and have a nice large head to help spread the load evenly. I’m planning to use these AN fittings for the fuel quantity gauges. They have Flared ends on both sides, and one side has a bulkhead attachment. My plan (for now at least) is to set up the fuel quantity sight gauges outboard of the fuselage frame, on the inboard side of the root rib. This will eliminate the need for any flexible tubing.
The Wicks price was pretty good on aluminum pull rivets for the door and window skins. The 90 degree AN fitting is for the fuel quantity gauge.
I didn’t want to use tempur foam for the entire seat cushions for a couple of reasons. Cost and weight were two factors, since the tempur foam had more of each. Another reason was the recommendation of a professional interior guy that gave a presentation about how to build seats. Another Bearhawk builder named Dave Lenart recommended Rochford Supply for the foam. The higher density option is 4526, with the softer 3319. The 1″ thick harder stuff goes over the tempur foam, then the softer 2″ thick stuff goes on top of that. The seat back is 2″ 3319 by itself.
The seat foam cushions came from Rochford Supply
Foam Cinnamon Roll
Thanks for Visiting! • This Entry is from January 6, 2010 at 5:30 pm
Today I finished the aluminum belly piece, at least for now. I wanted to further test my wingtip strip technique, so I put in a few rivets.
I'm using the -4 rivets to fill the holes from the first round of wingtip screws, and the -3 rivets to fill the holes from the old rivets.
Here's the results of an order from the Yard, thanks to a little Christmas money.
Thanks for Visiting! • This Entry is from December 31, 2009 at 6:00 pm
I only had half an hour to work today, but I made up another aluminum attach/stiffener for the belly panels to join with. When I drilled the holes, it turns out that the angle piece wasn’t wide enough, and thus the edge distance from the rivets was way too small. See pictures in the next entry.
Thanks for Visiting! • This Entry is from December 16, 2009 at 11:00 am
Today I worked on installing the left side belly panel. It is the same as yesterday’s entry, but just on the other side of the airplane.
Here is the left side still as a blank.
Here's a picture of me trimming the part.
Here's my first attempt at a piece to use for joining the two panels together. It is way too skinny!
Thanks for Visiting! • This Entry is from December 15, 2009 at 6:00 pm
Today I was working on the new aluminum piece that goes on the belly just aft of the exhaust tunnel. I decided to remake these pieces because of some mismatched holes, and so that I could make the panel in two pieces. By making the left and right halves separate, I feel like I can have a closer fit around the landing gear shock struts, and I can add a dual-purpose aluminum angle joining and stiffening piece in the middle.
I started out by using the old one-piece belly section as a guide. I used .025 2024T3 stock to cut the flat blanks, then slowly started adding in the various perimeter shapes. I bent the very slight bend on my toy bench top brake, and then cut and trim to make the fit just right. Here are some pictures of the part clecoed in place.
Here is a view of the right side panel from above. The floorboards are out in this picture.
Here is another view from above, including the new aluminum side piece, which joins to this belly piece.
This picture is looking up from the left side.
Here is the mostly finished part. It still lacks a joining tab aft of the landing gear hole, and hasn't been dimpled yet. I've been holding off on dimpling any of the boot cowl parts, since I'm still not entirely sure about how all of that is going to go together.
Thanks for Visiting! • This Entry is from December 14, 2009 at 2:15 pm
Here I am deburring the aluminum panel that goes on the right side.
Today I spent some time trimming the panel for the right side. The file seems to be quite effective, especially when I follow it with some 150 Aluminum Oxide emery cloth.
Thanks for Visiting! • This Entry is from December 8, 2009 at 8:00 pm
I wanted to get in a little more welding practice and I needed to make a gift for our dirty santa gift exchange, so I made this guy out of some scrap materials:
Evil Creature
It was the most evil-looking creature that I could create.
Thanks for Visiting! • This Entry is from December 6, 2009 at 8:27 pm
Welding the other side of the fuselage went much faster, and it turned out better.
New Steel Support in Place
I used a little rattle-can primer to keep the metal from rusting. I’ll replace that with some epoxy primer when the weather warms up, so that I can be sure that the covering process won’t lift the paint.
Thanks for Visiting! • This Entry is from December 1, 2009 at 5:00 pm
I decided that I didn’t like the idea of using aluminum angle as the aft support for the panel that goes under the door. This was mostly because I couldn’t think of a way to attach the aluminum angle very cleanly, so I figured I’d try to make one out of steel. I would be able to weld the steel to the fuselage, making for a much cleaner attachment. I saw that Bob specified .032 mild steel for the bulkhead at the trailing edge of the boot cowl, so I used .030 for this piece. It took me a little while to get it cut to shape and to bend it on my little toy brake, but I was very pleasesd with the finished product. I bent the trailing edge also, partly to increase the strength of the part and partly to be sure that it doesn’t chafe the fabric.
Aluminum Angle on top, steel blank ready to bend.
Aluminum Angle on top, steel blank ready to bend.
I made a paper template of the flat piece before I bent it.
I was a little bit worried about welding on the longeron. Making hangar doors is one thing, but welding on an expensive fuselage is another. I had a scrap piece of 3/4″ .049 (Bob’s T11) tubing like that of the longeron, so I started practicing. Since the tube is .049 and the tab is .030, it took a little practice to learn how to keep the heat off of the thinner piece. You can see the result.
Here you can see that the longeron sample tube is .049" thick compared to the .030 tab. I wanted to practice dealing with this difference.
It looks pretty good in the middle, but the ends need work.
This is a bad one. I started using narrower pieces just to make it harder.
Here is the end after trimming and ready to fit. Note the clearance for getting the floorboard in and out later
Here you can see the cleco side clamp holding the bottom ready for tacking.
Here is the left side in place
Here is the left side in place
I used a 90 degree die grinder with a scotchbrite pad to remove the paint on the longeron and door sill, which was quite effective. In the end I was pleased with the welding, and now I just have to make the other side.
Thanks for Visiting! • This Entry is from November 24, 2009 at 10:00 pm
Here is the inside view of the panel.
I had a surprise morning off from work due to some cancellations, so I spent a couple of hours working on a trailing edge support for the optional aluminum panel that goes under the door. I like the idea of using this panel for two main reasons. One is to make for a place to attach the lower strut fairing. The other is to protect the fabric in a high-traffic area. I didn’t really think of a good way to mount the aluminum angle support that the avipro manual describes. Some other builders have been able to figure out good ways to do it, so I picked up some 3/4″ angle and started working on making a piece.
Here is a mark so that I can trim the panel to match the other one next time I have it off.
Here I am working on it again.
The aluminum piece turned out nice enough, but I still wasn’t able to come up with a method of attachment that I liked.
Here is the end of the Aluminum angle. I tapered it some to try and limit the bulge on the longeron. The current shape still needs one more cut to allow the floorboard to be removed later.
Here is the angle rear support stuck in place. I sort of missed when I cut the slot for the tube. I don't really like it.
This is a view looking up from the bottom. The tunnel is on the left, and the aluminum belly piece is on the right. I'd like to bend the aluminum piece a little bit differently so that it lines up with the tunnel at the trailing edge.
Thanks for Visiting! • This Entry is from November 21, 2009 at 4:00 pm
I wanted to work on something other than the boot cowl for a little while, so I put together one of the door latches. I’m planning to use Bob’s design for the latch and will add some locks. I found some very compact cylinders at Home Depot for under $5 each. I got 3 that were keyed the same, just because I will probably not be able to buy more with that same lock again. Who knows, I might even use all of them. I also started looking at the optional aluminum panel under the door to see how that should go together.
Thanks for Visiting! • This Entry is from November 18, 2009 at 6:00 pm
I only had a few minutes to work today, but I got the exhaust tunnel attached and the little pieces clecoed. Last night we went to visit Bart’s RV-8 Project. He had the whole EAA chapter over and cooked some burgers.
Brandon and Wesley look over the people hole while Wade looks over the luggage compartment.
Bart explains the technical aspects of the flex-titanium jingle converter and other gadgets.
Page says that there are too many TV screens in there.
Jerry looks over Bart's RV
Bart’s project is coming along nicely and he’s going to put the engine on pretty soon.
Thanks for Visiting! • This Entry is from November 13, 2009 at 11:00 am
I was fairly proud of the way the firewall turned out, so I started working on the boot cowl. Richard built the instrument panel top with a removable triangle panel so that the joint is on the inside of the windshield. Bob’s prototype is just the opposite, with the hole for the cabane struts cut from the forward end. I like Richard’s way better, if for no other reason than to keep rain from having a potential leak under the windshield. The top and large side pieces were easy enough to figure out, but when I started working on the small access panels and the tunnel it took a little bit more time to get it all figured out. The panel that goes behind the tunnel is one that I would like to remake, so I didn’t want to count on its holes for guidance. Bob attached the boot cowl with screws on his prototype, but my preference would be for rivets. I asked him what his thoughts were now that he’s been flying for 10 years and 1000 hours or more, and he said that he hasn’t removed the panels once. This was good news, so I’ll plan to use rivets. This is an especially easy decision in the context of the little removable panels that Avipro incorporated. If I take off those panels, the tunnel, and the front floorboards, I would have very easy access to anything in that area.
Thanks for Visiting! • This Entry is from November 12, 2009 at 1:30 pm
Today I spent most of the day working in the hangar and it was great fun. I spent about an hour sorting out the dumped pile of hardware, and this was a good experience. I got to be pretty fast with identifying the #6 and #8 nutplates. I also started going through the wing counting hardware and checking on things. I used the tackle box pictured in the last post to make an inventory of the #6 screws for the wing inspection panels. There are 94 screws for each of the fuel tank panels… I sure hope I don’t have to take those off very often!
List of contents at the bottom of the tub, awaiting royalties from land o lakes.
I also finished counting hardware for the floorboards and the rear bulkhead. I put them into a butter tub and listed the requirements for each panel on the bottom of the tub.
On the topic of floorboards, I disconnected the fuel valve and unhooked a few of the fuel lines. The Usher gascolator is 3.75″ tall without the quick drain valve on the bottom, which means that it won’t fit between the floorboard and the bottom of the airplane. It is nice to be able to keep the bottom of the gascolator above the bottom of the airplane for fire protection in the event of a crash that removes the landing gear. I might try and find another home for the Usher and buy one of Bob’s gascolators since his is short enough to fit by the valve. It looks like Richard’s solution was to put a quick-drain at the bottom of the fuel valve also.
I would like to do it differently...
I also spent some time working on the elevator trim tab pushrods. I was concerned about the kinks in the bend, since they might pose as potential stress risers in service. To address this concern, I considered replacing the entire part, but it made much more sense to just replace the bent section. I got out the old AC 43.13 to see what it had to say about reparing tubing. I had a piece of tubing on hand that was larger than the 5/16, so I went that route.
Tubing repair with a larger piece per 43.13
I made the calculations using the diameter of the original tube.
Since the OD of the original tube was 5/16, it was easy to make some calculations about how much to overlap.
Look, it’s really me working on the stuff!
Jared Yates building a Bearhawk!
It looks like a hungry fish!
Wait a minute, that's the wrong kind of fish!
That's Better!
Ready to Weld
Next time- welding.
Thanks for Visiting! • This Entry is from November 11, 2009 at 6:45 pm
Here is a bit more time with working on the firewall, with no substantial content beyond the last post. I just got back into town from a nice weekend of fishing, and while I was gone the firewall didn’t trim itself.
Thanks for Visiting! • This Entry is from November 10, 2009 at 11:00 am
Today I finished welding the elevator trim pushrods:
Before and After
I also took an inventory of the fuel system and brakes to figure up which fittings I’ll need and how much line to use. I went back to read the Beartracks and realized that Bob recommended 5052 Aluminum lines instead of the softer and much cheaper 3003. I asked him about this and he said that he certainly prefers the 5052 because of it’s superior resistance to fatigue cracking, but that the 3003 would work fine too. He said that the 5052 was still quite workable in it’s -0 condition. I also asked him about a primer, and he said that it really wouldn’t be necessary. He used to add them to his airplanes early on, but he says now days he doesn’t even bother, especially on airplanes with an electric starter. He said that the accellerator pump used during starting can substitute instead.
Thanks for Visiting! • This Entry is from November 4, 2009 at 4:30 pm
Today I spent half an hour or so going through my list of bolts to buy again, this time with regard for the possibility of drilling our own solid bolts. It’s not very much time, but it’s all we could fit into the schedule today.
I did manage to dump out a little tackle box full of hardware, so next time I’ll have plenty to do.
Thanks for Visiting! • This Entry is from October 31, 2009 at 5:30 pm
I called Bob today and asked him about the AN210-3A vs -3B pulleys. He said either would work just fine.
I also asked him about the braided fuel line, which is something I’ve been waffling about for a while. The issue is that the current fuel lines are braided stainless lines instead of solid 3003 aluminum lines. The braided lines are popular with the race car crowd, but they are about much heavier per foot than the same size of Aluminum wire. In fact, the weight difference of 40 feet of 3/8′ is 1.76 pounds for the AL vs 5.8 pounds for the stainless. I don’t have any doubts that the stainless tubing is up to the task, since the pressure ratings and chemical resistance are great. I am worried about the longevity of the rubber line inside of the stainless tube. Is this concern well-founded? Probably not, but I really don’t know. By using these lines does it mean that the fuel system will only last 132 years instead of 250? or does it mean that the fuel system will only last 5 years instead of 50? Racecars aren’t built for the long term- they are built to be reliable for short periods but not for long periods- but that doesn’t necessarily mean that the fuel line won’t still last for as long as I need for it to.
I have consulted several expert opinions about the tubing, so I figured I might as well ask Bob what he thought. To summarize, he said that it should probably be fine, as long as the resistance to auto fuel was good (which I would say it is). He added that it was much more expensive and much heavier and thus couldn’t imagine why anyone would use it instead of the AL. Richard’s point was that it was much easier to install than the AL tubing. If I were starting from scratch I would have stuck with the AL tubing, but since the stainless is already paid for, cut to length, and installed, I will probably stick with it for now.
Thanks for Visiting! • This Entry is from October 28, 2009 at 12:26 pm
Today I continued my hardware patrol. I have been through the entire fuselage and the control stick and have replaced and/or noted what I’ll need to get to continue. I can definitely justify the expense of a drilling guide since I have lots of bolts that are good candidates for drilling for cotter keys.
I changed the bolt on the trim wheel to one with a hole in the shank and feel much better about it. I removed the doors since the hinge bolts were a little bit too short. Rather than just swapping the bolts I just took the doors all the way off so that I could get in and out easier. I made a few bolt changes on the elevator and flap controls to account for length and/or drilled bolts. I also went through the landing gear bolts and installed the ones with the correct grip length, now that I know how to do that. I didn’t have the proper drilled bolts on hand but I’ll have the gear off several other times and can replace them next time.
Using the torque wrench for the first time on the Bearhawk
I like to keep the chainsaw handy for deburring aluminum and notching 4130. Not really! I also managed to dump out the little tackle box full of nutplates and washers. I picked them up but haven’t sorted them back out yet. I’ll probably try to use household tubs with tight fitting lids since the clear tackle boxes don’t stay segregated very well. Either way it’s a waste of productive building time and I should try not to do such things.
Thanks for Visiting! • This Entry is from October 27, 2009 at 3:00 pm
Comparing the M4 to the Bearhawk
This morning started out with a morning of Young Eagles flights. I got to see Buck’s Maule M-4 for the first time. He flew 8 of the 31 kids, which was pretty amazing considering that he only had 2 seats. He said that the max gross weight is 2300 and the useful load is about 800 pounds. He has the same engine that we will use, though we probably won’t have the same Hartzell CS prop. His airplane is certainly beautiful, and I can’t wait to finish ours since it will be a very capable young eagle hauling machine. For now I just helped out with the paperwork and logisitics.
Filing the Brake Pedal to fit between the tabs
In the last entry I was starting to install the right side brake pedals when I realized that I was going to need to relocate some tools from the clubhouse. I loaded up my home-made work bench and took it over to the hangar, complete with an assortment of tools that I will hopefully not need in the clubhouse as much as I will need in the hangar. I had to file the attach side of the pedals a little bit so that they would fit between the attach tabs.
I started to mount them but realized that I didn’t have the right bolts. I have several little boxes of bolts but was surprised that none of them were the right length! Actually, I did have several that were the right length, but they were not drilled. Since the brake pedals and cylinders are subject to rotation, 43.13 states that they must not be secured with self-locking nuts- that means a drilled bolt with a cotter key. Since I knew that I was at least going to need those bolts, I figured I might as well go through the rest of the airplane and see what else I will need. Shipping from the aircraft hardware stores generally isn’t free or even cheap.
"Reserving" the hardware anywhere that I can
I also started to notice that some of the bolts that I had were already comitted to parts and assemblies that were temporarily removed from the airplane. For instance, the bolts that hold the flight control cables onto the control horns were not on the airplane, but were presumably in some of those little boxes of bolts. I made a sweep of about half of the fuselage, adding missing hardware as a way to mark it as “reserved.” In the process, I also saw some hardware that was not installed the way that I would have installed it, so I also resolved those minor conflicts. For instance, the rudder stop bolts weren’t really quite long enough to stick through the nylon lock nut, so I switched them out.
The longer bolts with 1, 2, 3 threads showing.
This was the case in several areas, and I also saw a few “subject to rotation” applications that I would have prefered to use with castle nuts and cotter keys.
This bolt should have a castle nut and cotter key per AC 43.13.
This bolt is too short since it doesn't have a thread protruding through the nylon.
I worked for 3 hours today and made notes of which hardware I was definitely going to need, which included a few small pieces, and a few big ones, like the engine mount bolts. I was somewhat surprised to see that I didn’t have any of those, since I figured that they would have been part of the Wicks hardware kit. So, I went to the Wicks hardware list to look and see if they were originally included. There on the list are some AN6-46 bolts, which are about the right length and in the right quantity (5). So either the wicks list has changed, I have the bolts somewhere else, or I don’t have them. I repeated this same process a couple of other times, referencing the Aircraft Spruce catalog for the grip length of each AN bolt, measuring what the grip length needed to be, and sorting through drawers to try and find the right stuff. All the while I was making a list of things to buy so that I can make one order and get most of what I need.
I have several bolts that are the right size but undrilled, so I might try and find a bolt drilling jig. For example, I have enough -6 bolts for the landing gear that I will probably not need anywhere else.
I also noticed that on the plans Bob calls for a pulley as AN210-3A, which is equivalent to MS24566-3A. Yet, the wicks kit included only -3B pulleys instead of the -3A’s listed on the plans. So far I haven’t resolved this discrepancy. The Aircraft Spruce catalog says that the -a and -b pulleys are the same dimensions but have a different type of bearing in the center. I suspect that they are interchangable but will probably have to call Bob or someone else to figure that out for sure. The funny thing is that in a case like this I picture an attorney questioning a witness. “Why didn’t you use the pulley specified in the plans?” Maybe that’s an idea for the next episode of Law and Order. I know it’s terrible to think of it that way, but that is the image that comes to mind in this case, and also quite often at work.
Some folks say that building airplanes isn’t as hard as people make it out to be. This is quite likely true, and an experienced airplane builder can certainly separate a harmless or seemingly meaningless discrepancy from a major or life threatening one. That is one certain difference between a new builder and a seasoned veteran- knowing what is worth fussing over and what isn’t that big of a deal. Without the benefit of that experience, I have to chase down even the smallest discrepancies to learn which category they fall under. The pulley difference is certainly just the first of many.
I also took some time to scratch my head and figure out which tabs went to which flying wire on the tail surfaces. I used the front view on page 1 of the plans to note the angles of each of the flying wire attachments and to notice that the bottom of the diamond shape uses attach points that are welded to the fuselage. With that information it was easy to sort out the remaining 6 tabs, after which I labeled them with a sharpie pen and set them aside with their associated hardware.
I think the process of “reserving” hardware by attaching it where it needs to go is going to be well worth the effort. This should keep me from double-booking a particular bolt and not realizing it until final assembly. I still need to do the same thing for the rest of the fuselage and the wings.
Thanks for Visiting! • This Entry is from October 26, 2009 at 6:00 pm
I’ve spent a few hours this week unpacking, building workshop infrastructure items, and taking inventory. I’m almost done adding shelves, racks, and work tables that I’ve made out of leftover building materials. One large corner rack is enough to store the ailerons, flaps, horizontal tail pieces, and most of the other parts.
Since Richard had not yet ordered an engine mount I requested one from Mark at Avipro back in September and just now got around to unpacking it. I was a little bit surprised to see that it had a fifth mounting lug, and I started to wonder if maybe it was actually a mount for the 540. It turns out that they started adding the fifth leg on the 360 mounts too, so it was the right one. I should add that I’ve been very pleased with the support that I’ve gotten from Mark, even though I wasn’t the one who wrote him a big check. I asked him about getting a set of brake pedals for the right side in hopes that I would be able to catch up with him at Bob’s Picnic tomorrow. It turns out that he wasn’t going to be going to the picnic but was glad to send me some for a small charge. While I was unpacking I found that Richard had a set already, so I had to call Mark to cancel the request. Anyone who can put up with that kind of trouble is worthy of respect and gratitude.
While moving the small boxes with hardware from the trailer I spilled a few of the drawers and had a handful of mixed hardware. I spent some time sorting through all of the drawers and making sure that the labels matched the contents. I certainly don’t want to buy hardware later that I acutally had in the wrong drawer.
I’m getting to the point now where I won’t have any excuses not to work on the airplane! I’ve spent several hours reading Richard’s Log and the Avipro Assembly Manual to try and see where we are going to start. I have several good starting points in mind and have also made a list of “things to be sure to do.” Likewise I have a list of “things to buy.”
Today I also installed a few flourescent light fixtures to help combat the shortening daylight hours. I’m sure that the guys from Alaska wouldn’t have any sympathy for me there.
Thanks for Visiting! • This Entry is from October 16, 2009 at 10:13 pm
The hangar is almost done, and the poor airplane has spent most of the summer in the trailer. When we get ready to move it out of the trailer and into the hangar, things will be much easier if the fuselage can sit on its own feet. It took a little bit of time to look over the plans and locate the bolts, but now it’s all done. There is quite a difference in height with the airplane on the landing gear, especially with no weight to stretch the struts. Now it’s taller than I am, and it is easy to see why Richard wanted to take the gear off for working in his garage.
Thanks for Visiting! • This Entry is from August 18, 2009 at 6:31 pm