Well, here I am, starting another page. This one starts with the actual installation of the firewall and moves forward from there. As always some work makes a big impression of progress and at other times I can spend days doing lots of work with little visible indication of progress other than pages covered in the manual.
3 Hours, 13 April, 2003
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| I put a second layer of thin q-cell mix on the open foam surfaces of the firewall cut-outs. | I potted the birch insert and put a two layer laminate over it. |
Next was a 12 X 16 inch two layer laminate, done on a waxed aluminum plate, I used peel ply on both sides. The forms for the engine mount reinforcements will be cut from this material. With a little sanding here and there the firewall is now ready to insert.
4 Hours, 14 April, 2003
The firewall was set in place, the exhaust tunnels and nose gear wheel well were trimmed to allow the firewall to set at the proper angle, and the firewall was hot glued into place at the waterline 100 marks with dabs of hot glue. The fuselage was again checked for plumb and the firewall then set to vertical.
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| The water level at the waterline 100 mark at the base of the vertical stabilizer | AND the water level at the waterline 100 mark at the cowl flange. The top mark is the the correct one. | |
| About 2/3 of the rear of the firewall is held in with a q-cell and Cabosil mix. Most of the front has been done. (The firewall was held in position using spacers cut from tongue depressors.) | Exhaust tunnel outline on the copilot's side. The material removed from the back side for the engine mounts (lower corner and lower center) show as dark areas as does the material removed for the exhaust tunnel. |
3 Hours, 15 April, 2003
I did more work with the q-cell and Cabosil mix and started cutting out the nose gear wheel well and exhaust tunnel openings.
Normally these openings are cut out several stages prior to this point, but I wanted the strength until the firewall was glassed in place. It would have also been a bit easier (but not much) to have cut them earlier. It sure would have been cleaner though.
After finishing the cutouts I was covered with the white dust as was a good portion of the shop. The "whole shop" fans were doing a whale of a job removing the dust, but a lot still settled out.
3 Hours, 16 April, 2003
I finished sealing the front of the fire wall in with the radiused Q-cell mix and did most of the interior side. The nose gear wheel well openings in the firewall and belly pan were trimmed and smoothed. Some fill is going to be needed at the front of the wheel well and exhaust tunnels. They had to be cut back to get the fire wall to fit, but once it was in place there is a 1/4 to 1/2 inch space in some spots.
| The rough cutout for the exhaust tunnel on the copilot's side showing the half inch lip around the bottom. This is to hold the "Fiberfax" insulation in place. | Firewall view showing Exhaust and nose gear cutouts. The cutout for the nose gear wheel well on the back side is clearly visible as is the wood block for the rudder pedal mount. |
| Interior of the exhaust tunnel on the pilot's side. Fire wall is at the bottom. The gap between the fire wall and exhaust tunnel is to be filled with a Q-cell mix. | An overall shot of the fuselage with the firewall in place. The water level is held in place at the front of the fuselage with the yellow tape. |
4 Hours, 18 April, 2003
The back side of the firewall is now sealed. I radiused the edges of the exhaust tunnels, and the nose gear wheel well. I also filled a good portion of the gaps between the wheel well, exhaust tunnels and the firewall.
3 Hours, 19 April, 2003
General trimming and cleaning of the fill done on the 18th as well as trying to figure out just how to do the lay-ups for the nose gear wheel well to fire wall. What's there is not quite the same as what is in the manual. The exhaust tunnels are about a half inch off center toward the pilot's side and there is no where near the room between the wheel well and what is shown in the drawings. That means some of the lay-ups will overlap...which shouldn't hurt anything.
3 Hours, 20 April, 2003
The rest of the gaps between the firewall and the exhaust tunnels were filled. Using a tongue depressor I forced the Q-cell mix into the gaps after cleaning and wetting the surface with Acetone. The gaps took a lot of filling, but they were too small for cutting foam inserts.
2 Hours, 21 April, 2003
I spent the evening trimming fill and smoothing the area on and around the wheel well and exhaust tunnels. I also discovered a couple areas that need a bit more fill radiused in.
4 Hours, 22 April, 2003
I cut, fitted, re-cut and refitted the nose gear to firewall lay-up #1 and discovered that you need to leave a lot of extra material for the bottom that covers the wheel well flange Oh, I did discover a couple more areas that needed some fill and a couple that didn't get smoothed enough.
3 Hours, 23 April, 2003
I did the second lay-up on the copilot's side of the nose gear wheel well and finished filling all the little spots I'd missed on the back side of the firewall and wheel well. There is still some fill and trim work left "inside" the wheel well and exhaust tunnels.
I'm down to less than half a gallon of resin so it's time to call NGA and order a couple more.
2 Hours, 24 April, 2003
I did the final (step 3) lay-up on the copilot's side of the nose gear wheel well and the first lay-up on the pilot's side.
| Some trimming of the rough lay-up edges is visible as light colored areas on the side of the wheel well. The white areas are q-cell fill | Copilot's side showing the new lay-up held in place using clothes pins. |
4 Hours, 25 April, 2003
I cut the cloth and did the second lay-up on the pilot's side. I put the heat lamps on to speed up the cure so I hope to get the third layer on yet tonight. The heat lamps raise the surface temperature to between 90 and 100 F. It gives a hard cure in about 20 minutes to an hour.
It worked and I did get the final lay-up on. Unfortunately it developed a
"blister" that needs to be filled.
It looks like it will not be difficult to fix.
Now it's on to cutting the 16, 51" X 4" cloth strips to lay-up around the front and rear of the firewall to fuselage seam.
3 Hours, 27 April 2003
I fitted the cloth strip to the pilot's side and added resin. I fitted as I went. Unfortunately the resin started to gel before I had the lay-up finished. As soon as I saw the resin was thickening I dumped it and made a new, but smaller batch. I quickly worked the fresh resin into the surface of the entire lay-up. This thinned the resin that was setting up and gave me enough time to finish stippling out the air bubbles and positioning the glass.
4 Hours, 28 April, 2003
I put in the first lay-up on the copilot's side and then added the second lay-up on the pilots side. This time I fitted the entire strips, using spring loaded clothes pins (bulldog clothes pins) to hold the cloth in place. The lay-ups were not only easier, but went much faster. I also found that a 60 gram batch of resin is just right to do each side with almost no waste. I also ordered 2 gallons of resin and catalyst from the NGA company.
2 Hours, 29 April, 2003
One more layer on each side for a total of 3 on the pilot's side and 2 on the copilot's side.
2 Hours, 30 April, 2003
Another day of doing a layer on each side. That finishes the pilot's side and leaves one more to go on the copilots side.
I probably would have finished the copilot's side as well, but we had a bunch of thunderstorms move in around 1:30 AM and I was a bit hesitant to work on lay-ups with a good possibility I might have to finish them in the dark.
1 Hour, 01 May, 2003
I only set up the cloth for the final lay-up. The rest of the time was spent organizing and cleaning a good portion of the shop. I also assembled another shelving unit.
1 Hour, 02 May, 2003
I finished that final lay-up on the co-pilots side.
2 Hours, 03 May, 2003
I finished the small lay-ups between the nose gear wheel well and the exhaust tunnels.
As I was mixing small batches of resin and still having a bit left over I decided to run a couple of experiments. I picked up some additional polyester cloth to use for peel ply as I was running low. I picked three kinds. I cut a 2 X 4 inch swatch from each and did a single layer lay-up on a piece of scrap (belly pan cutout for the exhaust tunnel). I only wiped off the surface and did no other prep.
I applied a coat of resin the the surface of the scrap, then laid a 4 X 6 inch piece of cloth on top of that. I then proceeded to saturate the cloth with resin and then laid the three swatches on top of the resin. Excess resin was worked out, leaving the top of each swatch smooth. This was cured at roughly 100F for 5 hours.
| Scrap cutout from exhaust tunnel with the three different materials used for peel ply |
Same scrap after resin cure and removal of the peel ply materials. |
The tan colored, light weight polyester left the smoothest finish, but wasn't strong enough to hold together while being pulled off the lay-up. The dark green polyester left the next smoothest finish and separated relatively easy. The light green polyester with the coarse weave left the best surface for the next lay-up, or painting, but took a fair effort to separate it from the lay-up.
So...It looks like the tan polyester is going to turn into a dust cover and the other two will become peel-ply.
As to testing the surface preparation: After pulling the peel-ply test strips off the lay-up, I grabbed one corner of the fiberglass, just beyond the area covered with resin. It only took a slight pull to separate the entire piece of resin and fiberglass from the underlying lay-ups of "old" material.
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This shows the surface after the original lay-up was peeled off. Hardly a mark. |
The next step was to make a larger lay-up using the light green material and preparing the old surface by cleaning it with a scotch-guard pad and then wiping it with Acetone. The surface was allowed to dry for about half an hour.
This time, after a 5 hour cure at 100F the peel-ply was removed and then I attempted to remove the lay-up. I was unable to separate the lay-up from the base material except for a very small area near the edge. Even then the materials tore rather than actually separating.
The only difference between the two tests was on the second I roughed up the surface with a "scotchbright" (tm) cloth and then cleaned it with Acetone.
In the first test the lay-up easily pulled off the base material. Actually easier than the peel ply removed from the lay-up. In the second the cloth and resin had basically become part of the base material.
| The complete test lay-up showing the base material, the fiberglass cloth with resin and the Polyester cloth. This cloth had a relatively coarse weave and when wet with resin you can see right through to the surface of the cloth. The light colored areas are resin poor. (dry) No effort was made to do a good lay-up | The peel ply (Polyester) pulled part way off. The coarse weave made for a rather tenacious grip. |
| The surface after removal of the peel ply. The surface has the same pattern as the peel ply cloth. There are no sharp spots at the edges of the glass cloth. Note the lay-up is barely visible where the peel ply had been used. | This was all I could do when trying to remove the fiberglass from the base material. I managed to get one corner loose, but beyond that the glass cloth was tearing. |
3 Hours, 04 May, 2003
I cut 8 strips of fiberglass cloth 51" X 4" on the 45 degree bias to use on the firewall to fuselage inside seam. I've also marked the edge lines on the firewall and fuselage walls.
4 Hours, 04 May, 2003
I re-sanded the areas for the lay-ups, did an Acetone wash, and fitted one of the 4 inch wide cloth strips. I mixed up a 50 gram batch of resin and wetted the area where the cloth would be placed. The next step was to carefully fit the cloth into place so it would reach the full required width. I had to mix a second batch as I ran out about 3/4 of the way through, but that was just about right as it was beginning to thicken. It hadn't started to gel yet, but it was only minutes away.
I was right. It does go much slower fitting the cloth on the inside. Soooo... I now have one layer done on the pilot's side. Only seven more lay-ups to go. Then the hard work starts with the engine mount reinforcements.
| It's not a real sharp photo, but this is the first lay-up, pilot's side. It went better than expected. but not as good as hoped. |
Joyce was going to shoot some photos of me doing the marking and lay-up, but I didn't get out there until after 1:00 and by then she's had a half nights sleep. <:-)) Tomorrow, I'm going to try and get an early start and get one layer on the copilot's side and another on the pilot's side. Now, let's see if I actually get it done.
3 Hours, 06 May, 2003
I fitted the cloth to the copilot's side and then did the lay-up. Later I fitted the cloth to the pilot's side and am working on a method to align the edges of the cloth so the lay-up can go faster and neater. The problem with tape is it pulls the fibers in the cloth. Although masking tape is usually not all that sticky it really hangs on the glass fibers.
3 Hours, 07 May, 2003
I finished the lay-up on the pilot's side and did one on the copilot's side as well. That makes two layers on each side. Two more to go
I went with the masking tape to hold the cloth in place. I cut a piece about an inch long, then fold one end over, sticky side to sticky side forming a tab. I put the end with the tab over the cloth and handle the tape enough to reduce the sticking power. It seems to have worked well so far.
3 Hours, 08 May, 2003
I had a couple of pieces of tape that ended up getting resin on them. The resin seems to react with the adhesive and remains sticky for a while so I decided to try something different. I ended up using tongue depressors. I fit the cloth "roughly into place and then hold it with a half a tongue depressor. I put one inch wide masking tape over the end of the tongue depressor. This holds the cloth in place AND lets me move the cloth a bit to position it more finely.
It only took 4 tongue depressors to hold the whole thing in place. The flexibility allowed me to coat the surface under the cloth with resin, stick the cloth in place and then fill the cloth with resin.
| Detail of the upper pilot's side corner before cutting the cloth to make the bend. |
The cloth for the pilot's side lay-up. |
2 Hours, 09 May, 2003
I fitted and installed the #3 lay-ups on both sides using the tongue depressor method to hold the cloth in place. It went much faster and easier, plus there was no residual tape to deal with.
1 Hour, 10 May, 2003
I fitted and installed the lay-up on the pilot's side and had planned on doing the copilot's side to finish up, but we had a lot of thunderstorms going through and I didn't relish the likelihood of having the lights go out part way through the final lay-up, so I held off on that one.
I used the peel ply to get a better finish and it worked well. By the time I finish the plane I may know how to use the stuff properly.
2 Hours, 11 May, 2003
| Top and left side with peel ply in place. I used a coarse weave Poly Ester cloth |
Detail of the area surrounding the lower engine mount area on the pilot's side. |
I finished up the copilot's side lay-up. Using peel ply, a bit of extra resin, and some pressure the lay-ups have smooth edges and surfaces. There were a couple of "bumps" that needed trimming and two air bubbles in the lower engine mount area on the copilot's side that need filling. All-in-all there is little left to finish the lay-ups around the periphery of the firewall.
I promoted one gallon of fresh resin tonight with 4 CC of CoNap. I do not use any DMA as an accelerator. The cure times are already too short with 5 CC of CoNap and no accelerator and minimal catalyst (MEKP). I have a second gallon stored in a cool spot in the basement.
2 Hours, 12 May, 2003
I filled the two air bubbles with resin. This consisted of drilling very small holes at the top and bottom of the void. I then mixed up a small batch of resin, and filled one of the syringes. The void was filled by placing the tip of the syringe tightly against the bottom hole and pressing the plunger. The voids are so thin (between layers) that the resin does not run back out.
The next step was to cut a strip of glass cloth 3 inches wide to fit around the outside of the exhaust tunnels. I did a little experimenting as to the placement of the cloth. This is now going to have to wait till we turn the fuselage back, right side up.
2 Hours, 13 May, 2003
Jim Powell came over and helped to turn the fuselage upside down. I did some trimming on the nose gear wheel well and exhaust tunnels. They need to be prepped for the two layer, inside lay-ups.
I figured I can re-level the fuselage easier than trying to do these lay-ups while laying on the floor and working over my head.
2 Hours, 14 May, 2003
Sand and file, sand and file, sand, file, and scrape. Measure, re-measure, sand and file, then repeat...I sure am glad I decided to turn the fuselage upside down to do this part!
2 Hours, 19 May, 2003
More sanding and trimming the fill in the gap between the exhaust tunnels and firewall. The inside of the exhaust tunnels has "Gel Coat" that has to be removed before the lay-ups are installed.
| Note the dark color. Instead of angling toward the bottom right, it should go straight across. Not only did the surface have to be sanded, but all traces of the gel coat had to be removed as it provides a very poor base for lay-ups. |
20 May, 2003
I'm not sure how much time I'll get in tonight. I have to clean the shop to clear the floor and also make it look half way presentable. I'm meeting a few of the guys at the EAA Education Center at 3BS to remove the engine and prop from an old Barracuda. Then we are bringing it out to store in the shop.
2 1/2 hours, 21 May, 2003
I'm really not counting these hours toward the G-III construction, although maybe I should... We removed accessories, wing tips, drained the oil from the IO-540 and have it ready for removal. I need to make a saw horse about two feet tall to support the tail of the Barracuda. When we take the engine off the tail is going to want to drop on the floor.
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| We were supposed to meet at the hanger at 4:30 to bring the Barracuda over. I arrived a half hour early and the guys had the plane over and the cowl was already off. | Just another view of the Barracuda showing the wing fences and flaps |
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That big 300 HP, IO-540 ready for the engine hoist. |
Jim Powell on the engine hoist getting ready to place the engine (IO-540 K1A5) into the back of my 4-Runner. |
The main tanks are full so I have to open all the doors to the hanger for ventilation and then drain the tanks into 5 gallon containers. I may just pull the plane outside and do that first.
I also need to inventory the panel. It's well equipped, but with older radios and gauges. I've already had one individual want to purchase the whole panel, but until I take stock, I have little idea as to its value.
And *still more* sanding in the wheel well and exhaust tunnels.
I should have some more photos up soon.
2 Hours, May 22, 2003
I did a test laminate on a waxed, flat aluminum plate using the new batch of Vinyl Ester Resin I promoted last week (NO DMA accelerator). I used 100% Nylon as a Peel Ply. Using 1% MEKP catalyst, the resin hardened properly and had a pot life (gel time) of about 25 minutes at 70 degrees F for a 60 gram batch. .
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The lay-up complete with peel ply waiting for the cure. |
A close up showing the edge and smooth surface of the lay-up |
1 Hour, May 23, 2003
More sanding in the exhaust tunnels and I filled and radiused the junction between the inside of the exhaust tunnels and the fire wall using a thick batch of resin with Cabosil and Q-Cells. After about a half hour I did the first lay-up between the inside of the exhaust tunnels and the fire wall.
1 Hour, May 24, 2003
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Exhaust tunnel to fire wall lay-up with peel ply in place. |
As seen from the front of the firewall. |
I did the second lay-up between the inside of the exhaust tunnels and the fire wall and used the Nylon peel ply along the edges. I trimmed the edges while it was still in the green state, then removed the peel ply about 3 hours later. I did not use peel ply against the front edge.
3 Hours, May 26, 2003
I finished sanding the tapered section inside the wheel well
The bottom of the fire wall is cut away in the front of the nose gear wheel well. The foam is cut back one half inch and then the back surface is removed on a radius of 4 1/2 inches. The well is 7 inches wide inside. The foam is then sanded down to give a taper from the edge of the cut out (4 1/2 inch radius) to the front surface at the top of the fire wall cut out. This area then gets sealed with a thin Q-cell mix which is followed by a two layer lay-up of bi-directional cloth cut on the 45 degree bias.
| One of the little detail sanders with the triangular pad worked very well for sanding the tapered section of the firewall inside the nose gear wheel well. | Detail of the tapered section after sanding, but prior to the two layer lay-up. This relief adds clearance for the nose gear |
4 Hours, 27 May, 2003
I sealed the tapered form section above the fire wall cut out. I also did the two layer lay-up to cover the tapered foam section.
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The tapered section with the two layer laminate finished. |
3 Hours, 28 May, 2003
I did the two U-shaped lay-ups at the inside front of the nose gear wheel well and fire wall junction. I skipped ahead in the manual by a couple of pages to do the inside of the nose gear wheel well. Otherwise I'd do the top work and then have to turn it upside down again and the old girl is puttin' on a wee bit 'a weight compared to when there were just the two fuselage halves glued together.
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Two U-shaped, three inch wide strips of BID cloth for the lay-ups. |
One "U" fitted into place. Note the bottom portion forms an inside angle while the top (above the cut out) forms an outside angle. The The upper portion is loosely held by tongue depressors taped to the side of the wheel well |
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Another view showing both the Upper inside and outside angles held in place. |
The two layer lay-up finished. Just a little trimming and sanding. Although none of this will be visible after assembly. |
As shown in the print and directions these can be a bit confusing. They go across the bottom corner and then up both sides all the way to the belly pan. They form "inside corners" until they reach the fire wall cut out, then the section that went across the inside of the fire wall is cut at the corner and from there to the end, folds around the front of the fire wall to become an outside corner. That is a 180 degree change.
This outside corner can be troublesome as it is a "sharp corner. The cloth does not want to lay flat on both sides of the corner. Pressing it flat on one side will cause it to raise on the other, forming an air bubble. There are two ways around this. One is to "break" the corner, or round it to an 1/8th inch radius. The other is to "glass up" the corner and then pull strips of peel ply over the glass around the corner and pull masking tape tight over the peel ply. With a little work the air bubbles can be worked out and a relatively sharp corner formed. As this is structural, rather than cosmetic and will be covered later on, I'd think the radiused corner would be the best and strongest route to follow. Naturally I used the peel ply and tape.
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The inside of the nose gear wheel well after the lay-ups were finished. |
It looks like the rear of the firewall is going to start another page.
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