2 hr
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( 3 / 15 )Using the mylar patterns, I cut out the tank side panels and bottom from 0.040 5052 aluminum sheet. I roughed the parts out using a snips, then cleaned up the cuts with a laminate trimmer bit in the Dremel following a straight edge (or spline in the case of the curved top pieces).
3 hr
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( 3 / 19 )I designed and printed my wing tank pattern on mylar (dimensional stability). The tank is designed to fit above the drag bracing diagonals. The top of the tank forms the top skin of the wing. The tank fits inside a 14" wing bay, between the front and rear spars.
Each wing tank has a capacity of 7.25 gallons. In level flight at the stall angle of attack the sump will unport with just under two gallons in the tank. The aircraft will also have at least a 5 gallon header tank, so this is not a big concern. The tank should completely drain under cruise conditions.
The drawings do not show the location of the sump drain, drain fitting, filler fitting or vent fitting. I have purchased a flush type cap from Aircraft Spruce. I also bought my tank fittings there.
2 hr
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( 3 / 25 )After a considerable period of indecision, I have decided to make riveted aluminum fuel tanks for the RW-11. The wet wings of the RV series is made like this. R.S. Hoover (AKA VDubber) posted an informative article covering the basics. Several builder sites illustrate the steps involved. It looks do-able.
I thought about forming a "lost foam" mold out of polystyrene then wrapping it with glass impregnated with epoxy. But then I'd need to make a hotwire saw to get the airfoil shaped plug. I'd have to get set up to use laminating resin. All lame excuses, but it just didn't appeal to me.
I also considered a welded tank. Tom Marston (spelling) who flies a Dakota Hawk out of New Richmond, WI suggested these. He had his made for him, but I didn't care for the price. I do have an acetylene set-up, and I've watched the Kent White videos. With practice, I could probably manage it. However, I would like the top skin of the tank to form the top of the wing for that bay. I am not convinced I can make the tank without warping the top skin too much. Also, I am almost certain to face the frustration of leaks.
So I arrived at a riveted tank. A top skin, two rib shaped sides, and a wrap that covers the front, bottom and rear of the tank. Add a couple of baffles, a flush cap, and couple of fitting flanges for vent and outlet and it should set to go. The bottom of the tank is a couple of inches above the bottom of the wing to allow the drag/anti-drag strut to pass underneath. Each wing tank should have a volume of 7.5 gallons. Combined with a 5 gallon header, I should have 3.5 hours of fuel on board.
I was able to find 5052-H32 sheet aluminum in 0.032, 0.040, and 0.063 thicknesses from a local sheet metal fabricator. 5052 is the recommended material for fuel tanks. I'd read of people using everything from 0.025 up to 0.050 for tanks. 0.050 was recommended for top skins, lest they get banged up during filling operations. After feeling the 0.040, I decided that was plenty heavy. A 4x10 sheet cost be $90. I could have gotten away with 0.032 for everything but the top, but that would have cost me another $60, and saved me less than a pound.
I also ordered 1/8" Avex rivets - the same used on the CH601 - and a ProSeal clone. More as I move along - hopefully with pictures.
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( 3 / 45 )I spent the evening modifying the bell housing from my Corvair core. The manual from William Wynne, as well as half a dozen web sites, show how it is done. I used a bandsaw and then files and a grinder to clean mine up. Here is a picture of mine, ready to be blasted with walnut hulls:
1 hr
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( 3.6 / 40 )I've been toying with the idea of having fuel injection/electronic ignition for the Corvair. A month ago or so I went ahead and ordered a MegaSquirt kit. I got a v2.2 board with MS-1 controller. I've installed the MSnS-E code which has all the features I need. Resolution on the MS-I is plenty adequate for a motor that only turns 3000 RPM. The V3 board might have made some of the wiring for wasted spark simpler, but I can make do with the older board just fine.
Ultimately, I want two controllers in the airplane for redundancy. The weight from additional injectors is minimal, so I can actually have redundant fuel systems as well.
The last few nights I have been soldering the controller and stim kits together. The unit is now working flawlessly on the bench. I have the spark side set up driving three coils in a wasted spark arrangement. The injector section is controlling two injectors, one per head.
This eliminates the distributor, so long as you get one of those plugs that allows a modified dizzy shaft to remain. The shaft drives the oil pump, so it must be kept in place.
If I can work out a cam sensor, I can have a pseudo-sequential system that I can trim the injector pulse for individual cylinders. This allows better control of the AF mixture and smoother operation lean of peak. If I do a good job porting the heads though, this may not be a big deal.
About mixture control: I have spent a lot of time digging through Lycoming and Continental literature, articles pro/con lean-of-peak, CAFE reports, SAE journals, and numerous other articles. Here is some of what I learned. Modern cars run a stoichiometric mixture in most situations. This is what the narrow band O2 sensors are designed to operate at, and is where fuel controllers (MS included) are tuned to operate. This is because a stoichiometric mixture, generally speaking, has the least amount of noxious emissions in the form of unburned hydrocarbons or NOx formed by the excess O2 that can combine with nitrogen at high temperatures.
This stoichiometric mixture corresponds to peak EGT. This isn't where we typically run aircraft engines, however. In fact, above 75% power, aircraft engine manufacturers specifically prohibit AF ratios near stoichiometric. In the past, manufacturers specified well rich of stoichiometric - 200 degrees "rich of peak" or so. Lately some manufacturers have come around to the idea that lean of peak is OK too. Right at peak is hard on an engine. Combustion dynamics are ripe for detonation and the temperatures are high, weakening the metal parts.
Somewhere rich of peak is where the engine makes more power for a given slug of air. For climbout on a hot day or to just go as fast as possible, you may want to have this setting available. Somewhere lean of peak is where the best efficiency is in terms of BSFC. You'd want this setting to get the most distance out of a tank of gas. So we have two different operation points, but the MS does not have a mixture control like we are used to in aircraft, so our control is limited. However, MSnS-E code does have switchable fuel and ignition maps, so with the flip of the switch, you can transition from best power to best economy. This is the path I have decided to try.
All that said, Mark Langford has a narrow band O2 gauge in his plane, and has been running close to stoichiometric with no apparent ill effects. This is according to his web site, and when I get closer to turning a prop with this set up, I will pick his brain about the details. He has spent a lot of effort making his engine detonation resistant, so he may be afforded some leeway in mixture setting.
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( 3 / 146 )One thing I've spent a lot of time researching is plaster and mortar. As I mentioned before, the mortar for old brick needs to be right. If you use the modern hard mortars, the softer brick will be destroyed. Modern mortar traps moisture within the brick and is less accommodating of the small movements a house makes.
Plaster and mortar from the late 1800's was lime based. This is softer than the premixed stuff you get at the local builders supply. You are lucky if you live in an area with many historic homes. This creates a market for contractors and suppliers experienced in these original building materials.
We aren't so lucky here. Type N mortar is as soft as you can find. If you ask for plaster you get taken to the section of the store with pre-mixed joint compound for drywall. Neither of these are suitable for restoration in my opinion. Fortunately, I have been able to locate sources for materials locally after considerable research.
When trying to get mix designs for plaster, most of the information I had spoke of lime putty. Much of that information came from Europe, and that is the material of choice over there. Quicklime is carefully slaked in water then left to age for a long period of time - up to several years. Quicklime isn't available in quantity around here, nor do I have several years to wait for it to slake properly. Lime putty is only available shipped, and it is rather expensive.
What we do have is hydrated "Type S" bagged lime known as Miracle Lime. This is fine, white, powdered lime that has already reacted with water. Mix it with the right amount of additional water (to a peanut butter or yogurt consistency), let it sit for a few days to a week, and you have lime putty suitable for all the mortar and plaster work on an older house. I mix it and store it in a plastic tote with a tight fitting lid. I can mix a 50 pound bag of lime easily in it, and the tight fitting lid prevents the lime from completing the carbonation reaction.
Reading the information out there, I get the feeling that many are under the impression that high calcite limes are superior. I think this has to do with magnesium affecting the creation or durability of frescos. It may also be due to the fact that magnesium oxide takes longer to hydrate. If it isn't hydrated by the time it's on the wall, it could hydrate there, expanding and destroying the finish. The lime I am using probably has 35% or greater magnesium content. It is pressure hydrated in an autoclave, ensuring the MgO is hydrated properly. Given that:
a) I won't likely have a fresco (although maybe polished plaster)
b) Properly made dolomitic lime is cures harder, is more plastic, and has better water retention than alternatives
c) The house was probably built using the readily available dolomitic lime
I have decided that the Miracle Lime will do just fine. It is very plastic and workable, and is surprisingly easy to finish. It quickly mixes with water to form a smooth paste. Best yet, it is $6 for a 50 lb bag at the local contractor supply company.
I've also read conflicting data on whether simply adding water to Miracle Lime really makes lime putty. So long as the bagged lime hasn't reacted with atmospheric CO2, I don't see how there could be a difference. I sure can't feel a difference, and the lime mortar gets hard as stone after a few weeks. The people claiming that there is a difference are usually selling the more expensive putty in a bucket, so I'm not inclined to believe there really is a difference.
I'm using 1 part lime putty with three parts sand for the scratch and brown coats. Sometimes I add one-third part of gauging plaster (see below) if I want the plaster to firm up quicker. The same mix ratio works out pretty well for the repointing mortar as well (sans gauging plaster).
I made a few other material substitutions. The scratch coat of plaster on our walls contained animal hair - presumably horse. I'm using polypropylene fibers instead, FiberMesh brand available at your local concrete supplier. It doesn't take much. I've gotten very solid keying into the lathe and no cracking when using a small handful of fibers in an ice cream pail of plaster.
For the surface coats of plaster, I am "gauging" the lime putty with a small amount of Durabond 90. I know what I said about joint compound above, but read the MSDS sheets. Durabond is almost all Plaster of Paris and powdered limestone - very close to gauging plaster. The Durabond 90 gives me plenty of working time to get the plaster on the walls and finished. Once Durabond is set, it does not soften when wet like premixed joint compound will. To make finish plaster, I take 1 part lime putty and form it into a dish on a scrap piece of countertop. Within that dish mix 1/3 to 1/2 part Durabond with water to a workable consistency. Once the Durabond is blended smooth, work the lime putty into the mix to make a nice finish plaster.
After much searching, I did find a supply company in Saint Paul, MN that sells fine marble dust in 50 lb bags. I will use this in the surface finish for the bathroom walls. I am experimenting with a Venetian Plaster recipe that is 1:1 lime putty to marble dust, with a small amount of olive oil soap (Kiss My Face) and linseed oil. Formulations will follow once I have some test panels made up.
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( 2.7 / 145 )We purchased our home in the spring of 2007. It is a nice sized brick house with a footing plan like a Greek cross. It was constructed in 1896, according to the county records and the date scratched in the mortar in the foundation. The architecture is Victorian - perhaps more accurately Folk Victorian. The style is not as ornate as Queen Anne. Turnings and scroll work make up the trim around the porches, and arch-top windows have brick dentil cornices.
;)
Given the age of the home, it is in very good shape. The foundation shows almost no evidence of settling. The brickwork is largely in good shape. The timber structure only has a few places where moisture damage is evident.
That's not to say that there is nothing to be done. Although the home has a new roof now, leaking and subsequent staining led the prior owners to cover portions of the plaster with drywall. We are taking a room at a time approach to restoring the original plaster.
Most of the original storm windows are gone. These were arch topped just like the primary windows and have a seamless look. Most were replaced with cheap aluminum storm windows. These really destroy the look of the home, and I seriously doubt that they perform as well as the original storms. I am making new storm windows to match the originals, and will be doing away with the aluminum units. The main windows will be treated with weatherstrip kits from Advanced Repair Technologies. The combination of original storm windows and tightly sealed main windows should perform nearly as well as new triple-pane windows, but for a fifth of the cost.
The sills of some of the windows have rotted or shrunk enough to allow moisture to enter the top of the brick. This has led to deterioration of the mortar under the windows (old lime mortars were responsible for wicking moisture from the surrounding brick and dissipating it into the air). We plan to repoint these areas as soon as possible.
A previous owner tried repointing the brick in one area at the back of the house. Unfortunately, they used modern portland cement based mortar, which caused the brick faces to spall off. Our repointing project will also involve replacing these bricks with ones from the stockpile that came with the house.
That's it for now. More as we dig into the restoration.
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( 3 / 110 )After finishing the rear spar last fall, the weather got too cold outside to work with the epoxy any longer. My wife is pregnant with boy #3, so I had been focusing on completing the extra bathroom, bedroom and family room that I was putting in the basement. We really need more space.
When the opportunity to get a larger home in the country recently presented itself, we jumped at it. The new house has a detached heated shop, a 55'x100' pole building that might make a good hangar, and enough land to have a 700' airstrip with clear approaches.
Unfortunately for the RW-11, I will be concentrating on finishing the renovations to our current home before the closing date. I am also hoping to get a new bathroom in the new house as well. Boy #3 is due in May. Don't expect to see anything here for a while.
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( 2.8 / 81 )I glued the top capstrip to the shear web for the rear spar.
1 hr
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