bearhawkproject.com Matt Kunkel's Bearhawk Build Log

12Jul/112.5 hrs

Re-Locating fuel selector (part 2)

A new mounting plate for the fuel valve was fabricated from .062 4130 plate utilizing the pattern made previously. The plate was welded in place and sprayed with corrosion inhibitor.

Filed under: Fuel System No Comments
9Jul/114 hrs

Re-Locating Fuel Selector (Planning)

This morning was spent planning, measuring, and visualizing the fuel system as it relates to the fuel valve and gascolator.  The location Avipro provides is a bit of a reach and it's right under the flap handle.  This creates a knuckle buster situation when operating the flaps (which as Jared Yates pointed out will be used a-lot more than the fuel valve).  It's also quite difficult to move this particular valve under the flap handle.  Because of these reasons, I'm re-locating it.

 

There isn't much depth between the floorboards and belly so everything is a tight fit.  Since the shock struts also run through the area the landing gear was temporarily installed to ensure clearance between all the parts.  I settled on a location closer to the seat, and beside the flap handle (not under it).  The shape of the plate needed to fit the area is very irregular so I made a template and verified the fit/clearance.

 

The fuel selector is a Newton SPRL 4-way valve and I really like the design.  The outlet is on the side (not bottom like Andair) so it's not too deep.  Another really nice feature is that it's positive locking and doesn't need a bump guard.  You have to lift the spring loaded selector to move between L/R/Off/Both.  One shortcoming is that the outlet port is on the front of the valve, which would work great for a tri gear plane.  Since I need the gascolator aft of the selector (lower on a conventional gear), I need the outlet port facing aft.  It's because of this, the markings on the valve are backward, for now.  I flipped the valve around, so the outlet is aft.   I'll either turn the marking's off and re-engrave the top plate OR I'll make a coverplate with correct markings.  R/L will be correct but the Both/Off positions will swap places.

Filed under: Fuel System No Comments
5Jul/114 hrs

Overhead Lighting Brackets

I added brackets for some gooseneck map lights.  The .032 sheet was bent with a .25" flange for stiffness leaving 1.25" width for mounting.  Fabbed the brackets, prepped the area, welded, and sprayed some crc sp-400 corrosion protector.

Filed under: Fuselage No Comments
3Jul/114 hrs

Ventral Fin Stand-Off

I added a fitting for a ventral fin which may be necessary to add vertical area to the plane if placed on floats.  The need for a ventral fin is dictated by engine/propellor selection (power) and the profile of the floats in the water.  I measured, drafted a pattern, fabricated the part, welded, and sprayed corrosion protection today.  The stand-off is made of .063 4130 steel.

 

Filed under: Fuselage No Comments
26Oct/102 hrs

Floor Fairlead Cutouts

This evening I cut the cargo area floor panel to fit around the rudder cable fairleads I added.  I also sanded some filler I added to the trim tab cut-out tubes.  I didn't wait until the epoxy set up enough for the previous round of filler so I had to add to it to make the filled area flush.

Filed under: Fuselage 1 Comment
24Oct/106 hrs

Counterbalances, Tube Plugs, Trim Tab Hinges

I finished trimming the elevator counterbalances so they are fully recessed within the tubes (won't create bulges in the fabric).  Most of this had been done previously, a little touch up today.

 

The elevator halves were hung with the requisite 1lb weight at 7.5" from the hinge line (as calculated by Russ Erb and verified by other builders).  I drilled the weight until it is just slightly heavy.   An inspection cover over the weight will allow for final balance after covering/finish if necessary (I could add weight too by filling one of the drilled holes with epoxy/shot slurry).  According to the manufacturer and other users, Stewart Systems tends to come out light, so I will likely have to trim the weight further.

 

I also trimmed the epoxy/microballoon tube plugs around the trim tabs and added a little in places where the epoxy ran.  Lastlly, I finished reaming the trim tab hinge tubes to accept a 3/16 hinge pin.  There was quite a bit of welding flash in the hinges and some were mishapen or mis aligned..  I used a drill bit brazed onto a rod for some of the work.  I used a reamer for other parts where the drill bit wasn't making a nice round hole.  To finish things off I assembled the hinge tabs with a 3/16 reamer in place of the hinge pin and rotated them a few times.  This made for a nice snug fit on the hinge pins.

Filed under: Empennage No Comments
21Oct/102 hrs

Elevator Counterbalance Trimming – 2

Worked on trimming counterbalance on port elevator half.  Short on time again today but some progress was made.

Filed under: Empennage No Comments
19Oct/103 hrs

Elevator counterbalance trimming – 1

Today  I started trimming the counterbalances previously poured.  Not much time to work today, so this will be split among several sessions.

Filed under: Empennage No Comments
13Oct/103 hrs

Cast Elevator Counterbalances

Today I cast the lead counterbalances into the elevator.  I used a steel plate on the bottom of the ribs to create sort of a bowl to pour the lead into.  I used some high temp rtv to create a gap seal and clamped the plate in place.  It's amazing how thin lead is when melted.  Is about the same viscosity of water with a much much greater mass, a-lot like mercury.  I still had some leakage but learned to pour a little in the bottom, let it set up, pour a little more, etc until I had a nice base to pour the rest onto (with no leaks).

 

I made a smelting pot from on old metal coffee can, and used a white gas camp stove as a heat source.  The lead shot melted surprisingly fast, I used a blow torch to help speed things up and to help flow the lead back under the flanges on the elevator.  Unfortunately I didn't get pictures of the melting/pouring process since I did it alone and had to work very fast.

Filed under: Empennage No Comments
12Oct/103 hrs

Prepped and Primed Elevator Counterbalance Areas

Filed under: Empennage No Comments