I am currently waiting for my friend Ed http://mmwauto.com/index.php/services.html to finish painting the horizontal/Vertical fin fairing , the canopy Yarmulke and the tip caps for the vert fin and rudder.Meanwhile I started installation of the engine wiring and instrumentation. I bought a set of all electronic gauges from Jim Weibe http://www.beliteaircraft.com/ I was particularly interested in his electronic fuel gauge. Its unfortunate that I did not plan for these gauges from the beginning. I could have incorporated a flat section into the fuel tank that would have accepted the sender. However, the method I came up should work just fine. The fuel sensor appears to be a variable capacitance sender. There is a outer tube that acts as one plate and a center 14 gauge wire that acts as the other plate. As the fuel enters this tube, the fuel will act as a variable dielectric and upset the balance of a capacitance bridge. The difference is read on the fuel gauge. There are two standard lengths of the senders, 12 and 24 inches. You can trim the probe to any length you need. The base of the probe mounts to a 3/16" thick plate that is drilled and tapped. To lessen the weight and add additional bond area, I drilled lightening holes between the threaded holes. I countersunk both faces so Flox, which will be forced through, will act as a positive lock. I started the process by filling the threaded holes with carnuba wax. I coated the fasteners with carnuba and inserted them into the plate. I sanded the bond surface with 100 grit paper and then wiped the bond surface with MEK. This is then carefully set aside and not allowed to come into contact with any contaminants.
|Fuel level sender base|
|Wires after routing|
This shows the sender installation.
I want to be able to remove the canopy when I am working on the plane and when it is being suspended from the hanger ceiling at my local airport. So that means that all wiring must terminate right at the canopy hinge with a multi pin plug. I am looking for that plug right now. I will need to route a Tygon tube from the wing pitot to the airspeed pressure sensor mounted behind the airspeed gauge. This tube will also have to route to the area of the plug. I need to figure out a quick disconnect not only at the canopy hinge, but at the wing root also.
|Iso view of the engine installation|
This shows the additional baffle plate I added to firewall so I can seal the gap around the cheek cowls. I am using the stock carb. air filter, but I would like to find a more compact unit, as it is now, I have to bend the filter aft inside the cheek cowl. It will work, but I would like to find a better filter.
So a little searching and some more scrounging and I should have the instruments all installed. It feels good to make final saftied connections. the last job before covering will be to re-rig the wings and mount the ailerons and route the aileron cables. Also today I bought 3 spring scales and I weighed the whole mess!! No estimating, because all of the parts are completed. assuming 18 lbs for complete cover and paint (should be conservative) I weight 243 lbs!!!! That is a huge relief, but this is the reason the prototype has no brakes or starter. however, my initial prop weighs 8 lbs, this will reduce to 1.5 lbs when I finally choose the correct diameter and pitch. I will ask CGS props to carve me a fixed spruce prop. If I have time I will carve my own. I use the Fred Weick method he outlined in a NACA pub from 1929. Come think of it, I will carve my own and detail it in the blog, its really a very simple process and 90% of the work can be done on a band saw.