Max 1030

Mounting the strobe

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The best place for the strobe is on top of the fin. Getting the wiring up through the fin will be difficult since I’ve already covered the fin. Looks like I need to make a 3 foot drill bit.

I got a 1/4 steel rod and sharpened the end to a point on the sander.

Tip of homemade drill bit
Tip of homemade drill bit

Then I used a dremel with a cut off wheel and made two groves 180° apart.

Homemade three foot drill bit
Homemade three foot drill bit

It’s a little slow but works well.

The hard part was getting the angle just right to drill right down the center of the nose ribs. To assist with this I made a small guide block, similar to the guide block used to drill the axle hole in the landing gear.
Once the hole was drilled the wires were routed through the nose of the fin. A hole was drilled in the bottom of the strobe and the strobe base mounted into the fin.
Terminal ends were added to the wire and connected to the strobe.

Connecting wires inside the strobe base
Connecting wires inside the strobe base

With the fin mounted the wires were connected and the strobe tested.

LED strobe
LED strobe

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Strobe

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In the quest for an affordable strobe I found many suggestions. Some people have used fire alarm strobes, I considered this.

Others just say buy one so I looked into that. The Microavionics MM030 strobe is about $150 and has a xenon flash strobe powered with 20 joules and weighs about 9.5oz. Not really sure how tall or wide it is.

The cheapest pre-made strobe I found is the Skysports Bright Star Strobe avaliable from Aircraft Spruce. It has dual xenon flash tubes using 8 joules, weighs “under 5oz” and is 2.75″ wide and 4″ tall.

In my opinion the Skysports strobe is not bright enough. Sure it meets the need for twilight flying but 99% of my flying will be on sunny days. The main reason I want a strobe is to make my slow small airplane more visible to other faster approaching aircraft, this is especially important when taking off and landing.

I also wanted to avoid a xenon flash tube, the high voltage can cause radio interference. Sure properly grounded it should not be an issue but this is a wood airplane. 

After looking I found a nice LED light that fits the bill. It weighs 7oz so it’s lighter than the MM030 but heavier than the Skysports. At 5.5″ tall and 2.75″ wide it has the same footprint as the Skysports just 1.5″ taller. Most importantly it is very bright. It also ended up being the cheapest at $40.49 with free shipping.

LED strobe
LED strobe

Unexpectedly this LED light did cause RF interference with the radio. Each time it flashed you could hear a hiss on the radio. Adding a ferrite core to the power wires resolved this problem. The core was salvaged from an old VGA cable and fits nicely inside the bottom of the light.

I’ll cover mounting it in a future post.

AIS Markings

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Long ago I ordered some operating range decals from aircraftspruce.com so I can mark the air speed indicator. While the decals worked ok they are a little short. The more expensive decals they sell are full circles so no worries about being too short.

I needed more green than what is provided
I needed more green than what is provided

I labeled the stall speed with and without flaps, maximum speed with flaps extend, normal operating range, cautionary range and maximum speed. For three dollar decals they look very professional but you might need two of them to get the job done.

AIS tubing

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The air speed indicator requires some tubing that goes to the pitot tube and static ports. Previously I wrote about the static port installation, you can read about that here. This article covers the tubing for the pitot tube. I decided to use the removable pitot tube kit, sold by Leading Edge Airfoils, so I can remove the pitot tube when removing the wings.

I thought that putting it out the leading edge of the wing would look nice, trouble is I already built the wings so installing is not going to be a simple task. I created two wood blocks, one to fit inside the wing just below the leading edge stringer and another to fit in the outside of the wing to support the pitot tube mount.

Pitot tube mount and blocks
Pitot tube mount and blocks

The inside block was threaded to match the pitot tube mount. I added CA glue to the wood as I tapped the threads to ensure the threads remain strong.

Pitot tube mount and blocks
Pitot tube mount and blocks

The only access hole in the leading edge is where the strut mounts are located so that’s where I decided to mount it. I cut a hole in the leading edge ply and epoxied the threaded block in place.

Pitot tube hole in leading edge
Pitot tube hole in leading edge

All of that was done about a year ago, now that the wing is covered in fabric and painted, time to finish. I first run the vinyl tube inside the leading edge from the root to the access hole. There I slid the tube through a 3/4″ deep well socket, then the plastic nut and out the threaded hole.

Pitot tube mount nut
Pitot tube mount nut
3/4 socket to tighten pitot mount nut
3/4 socket to tighten pitot mount nut
Vinyl hose for pitot tube
Vinyl hose for pitot tube

The outside wood spacer block was slid over the pitot tube mount and then the vinyl tube was slid over the barbs on the mount.

Pitot mount and external spacer
Pitot mount and external spacer

The mount was threaded into the wing, I had to ensure that the vinyl tube inside the leading edge was rotating too instead of rolling up into a knot. Now for the hard part, I used some long forceps to get the plastic nut started on the pitot mount. To tighten the nut I dig around my junk drawer and found the perfect tool, an old useless screwdriver. After a trip to the disc sander and vice it now looks like this.

Custom wrench
Custom wrench

My newly designed wrench fits into the hole on the side of the socket allowing me to turn the socket about 1/4 turn at a time.

Turning socket with wrench
Turning socket with wrench

I used my $20 USB endoscope camera hooked up to my phone so I could see if the nut was indeed fully tight.

Pitot mount nut tightened
Pitot mount nut tightened

I retrieved the socket using a magnetic pickup tool.

Retrieved socket with magnet
Retrieved socket with magnet

Next I made a plate to hold the quick disconnect.

Quick disconnect mounting plate
Quick disconnect mounting plate

Here I forgot to take a picture. Before I drilled that 5/8″ hole in the plate above, I had only drilled a small 1/16″ hole at the center. While chewing some gum I installed the wing so I could mark the center of the quick disconnect on the fuselage.

Tasty center finder
Tasty center finder

Grabbed the hole saw and drilled a hole in the fuselage side. 

Hole in fuselage for pitot disconnect
Hole in fuselage for pitot disconnect

The vinyl tubing was cut to length, disconnect plate varnished and disconnect installed.

Pitot quick disconnect on wing
Pitot quick disconnect on wing

The 90° disconnect inside the fuselage was attached to the vinyl tubing that runs up to the AIS.

Pitot quick disconnect inside fuselage
Pitot quick disconnect inside fuselage

I’m using the same valved disconnects I used for the fuel lines. So I don’t have to worry about bugs crawling inside my tubing and clogging it while I have the wings removed.
The final result looks great, hope it works well too!

Remove Before Flight!

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Various parts of the airplane need to be locked for safety or plugged to keep bugs/debris out when the airplane is parked and not in use. These locks and plugs are usually attached to a flag stating “Remove Before Flight.” I purchased some inexpensive, well made,  keychains for my flags.

Remove before flight keychain
Remove before flight keychain

The BRS ( aka ballistic parachute ) came with it’s own flag. This is for safety because you do not want to accidently activate it. It does not have ballistic in it’s name for show, that rocket needs treated like a loaded gun.

BRS remove before flight
BRS remove before flight

The static ports are used to measure atmospheric air pressure and are integral to the air speed indicator (AIS) and altimeter. I bent a small piece of music wire that attaches to the keychain and doors snuggly into the static port.

Remove before flight in static port
Remove before flight in static port

Maybe not necessary but seemed like a good idea I got a small rubber stopper and eye bolt to make a plug for the exhaust. 

Exhaust Remove Before Flight
Exhaust Remove Before Flight

The pitot tube, for the AIS, was a little more difficult to block because the tube can be removed. We not to plug the hole the tube goes in or the end of the tube when it’s installed. 

Drilled a hole in the side of a 1/4″ aluminum rod to attach the form.

aluminum rod for pitot flag
aluminum rod for pitot flag

The rod can easily plug the pitot holder.

Pitot mount and plug
Pitot mount and plug

Added a piece of 1/4″ ID tubing, this will be used to plug the tube when it is installed on the airplane.

Pitot Remove Before Flight flag
Pitot Remove Before Flight flag

With the pitot tube removed the hole is easily plugged and looks nice.

Pitot mount plugged with flag while pitot tube is removed
Pitot mount plugged with flag while pitot tube is removed

When the pitot tube is installed the same flag can plug the hole. The only downside is that it does add a couple inches to the length.

Pitot tube plugged with flag
Pitot tube plugged with flag

Wing Tips

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The droop wing tips I got from TEAM had some flaws. A few voids here and there were no big deal but not fitting the leading edge was a problem.

To fix the front I ground out the seam on the wing tip. Some wax paper was taped onto the leading edge of the wing. Polyester resin was mixed up and new fiberglass added to the wing tip. Another piece of wax paper was placed on top of the wet fiberglass and rubber bands were used to hold everything in pace while the resin dried. 

Rubber bands hold fiberglass against wing while curing

The edge of the wing tips are not straight so I decided to mount them, drill the holes and then trim the edge based on the path of the screw holes.

I marked a line on the wing 2″ from the end around the perimeter, this will be used as a reference to drill the screw holes into the fiberglass tip. The tip was mounted and clamped in place then measured 1.5″ from the line and drilled holes into the wing tip every two inches. This places the center of the screws 1/2″ from the edge.
I would drill a few holes, remove the tip and enlarge the hole in the fiberglass and then bolt it back into the wing and drill a few more holes. Once all the screws were in place I used them as a reference to mark a straight trim line around the tip then cut off all the excess material. 

Wing tip straight, trimmed edge
Bottom view of wing tip
Bottom view of wing tip

A 1/8″ plywood piece was cut and fit to seal the end of the tip at the aileron. 

Plywood to fill gap in tip at aileron
Plywood to fill gap in tip at aileron

It is held in place with some fiberglass cloth and resin from the inside of the tip.

Plywood held in place with fiberglass and resin
Plywood held in place with fiberglass and resin

The tip did not match up to the aileron as you can see here. Not really necessary but I wanted a better look.

Wing tip is a little short

Using a thin diamond cutting blade on the Dremel I cut a slot at the back of the tip.

Cut thin slot in back of wing tip
Cut thin slot in back of wing tip

Then I used some polyester resin to glue in a piece of 1/64″ plywood that I pulled from my R/C airplane parts bin. This was a little tricky to get right because it can easily flare in or out if your not paying attention.

Glue in 1/64 inch plywood
Glue in 1/64″ plywood

Once that dried I mounted the tip onto the wing and marked where I wanted the tip to end.

Mark end of wing tip
Mark end of wing tip

The plywood was cut along the mark, then polyester resin and fiberglass cloth was used to build up the tip to the proper thickness.

Build up fiberglass
Build up fiberglass

After applying some filler and sanding the extended wing tip looks great.

Apply filler and sand smooth
Apply filler and sand smooth

Filler was applied to all the other imperfections, the entire surface sanded and primer was applied.

Painting wing tips
Painting wing tips
 
A couple base coats of white were applied and finally the red top coat. Installed they look great!

Front view of wing tip
Front view of wing tip
Wing tip side view
Wing tip side view
Gap between aileron and tip
Gap between aileron and tip
Rear view of wing tip
Rear view of wing tip

One last modification was needed to the tips so I can easily remove the aileron with having to remove the tip. I modified the SHCS that hold the bearings on the ends of the aileron so I can install a safety pin so I know the aileron cannot fall off.

Aileron safety modification
Aileron safety modification

To make it easy to pull the pin I drilled a 7/8″ hole in the bottom of the tip directly under the aileron bearing and plugged it with a solid rubber grommet.

Drill and plug hole to access safety pin
Drill and plug hole to access safety pin

Installing the pin is not terribly difficult through the.

Safety pin for aileron hinge
Safety pin for aileron hinge

Wing Tanks Installed

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To cushion the bottom of the tank I got some 1/8″ thick neoprene. The best deal I found was sold as “tool box drawer liner.” I cut it so it is wider than the bottom so it wrapped up the sides a little then notched out the inboard rear edge to match the plywood.

The tank needed two holes, one for the drain and one for the fuel level sensor. I first drilled a small pilot hole then used a 1/2″ forsner bit. Never use a regular twist drill bit for this step, you will end up with a triangular shaped hole instead of perfectly round and the bushing won’t seal. 

Small pilot hole in tank
Small pilot hole in tank
1/2 inch hole in tank drilled with forsner bit
1/2 inch hole in tank drilled with forsner bit

Then installed the rubber bushing.

Fuel tank bushing
Fuel tank bushing

At this point I realized this particular tank is too deformed to install the fuel level sensor because the top and bottom are curved inward so there is not enough clearance for the sensor.

Knowing these tanks do expand the first time they are filled with gasoline I had to stop the installation and fill this tank with gas and hope that resolves the problem. After a few days the tank was still deformed, so I sealed the tank and put a few psi of air pressure in it. The following day I removed the air pressure and let it sit with gasoline in it. After a few more days the tank is back to its normal shape and has held that shape for over a week. 

Now I can install the fuel level sensor. I made sure that the sensor was about 1/4″ above the bottom of the tank and pressed it into the bushing.

Tank with fuel level sensor installed
Tank with fuel level sensor installed

I was concerned that the polycarbonate cover might bump the calibration switch on the sender so I cut a ring of plywood to protect the switch. I used some silicone to hold the ring in place.

Small plywood ring to protect calibration button
Small plywood ring to protect calibration button

The drain hole in the bottom of the tank was drilled and fittings installed.

Tank drain
Tank drain

Now the tank was installed into the wing. To hold it in place I purchased some tie down straps. They were way too long so I cut them shorter and heat welded the end so it does not fray. I routed then under the plywood and diagonal supports then over the top of the tanks. 

Two straps hold tank in place
Two straps hold tank in place
Tank strap buckle
Tank strap buckle

The fuel line was routed from the elbow to a tee. Then to the drain and quick disconnect. This was not an easy task to accomplish without kinking the lines. It would have been easier if the quick disconnect was moved an inch or two forward but that would have made the quick disconnect higher which is undesired and more likely to get bumped by my elbows when sitting in the cockpit. Maybe cutting one barb off of the tee would help too.

Fuel line routing in wing
Fuel line routing in wing
Fuel line routing in wing
Fuel line routing in wing

After installing the cover panel I’m amazed at how well it looks. 

Tank cover panel installed
Tank cover panel installed

Not much remains on the wings now. Grease aileron bearings, safety wire aileron bracket bolts, install wing tips and I need to get the rest of the wing polished so it shines like the tank cover and ailerons.

Fuel Sender Wires

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Time to route the fuel level sensor wires. The first thing I did was mount the wings and locate a location to drill a hole for the wires. After drilling the hole I added a grommet.

After locating the hole I determined how much wire needs to protrude from the fuselage so they can be easily disconnected after removing the wing.

The sensor outputs need routed to the fuel selector switch so I decided to make some splices near the sender switch to accommodate this. I routed the left fuel sensor wire down the left fuselage side, across the floor and up the right side and through the grommet. On the right side near the fuel selector switch I spliced in the fuel selector and right side sender wires.

The red and black (power and ground) are spliced to the right side sender so both senders get power. The white wires from each sender are spliced to the wire going to the selector switch, right to red and left to black. The white wire from the dash and to the selector were spliced.

Terminal ends were added, the resulting harness looks pretty good.

Behind the dash the black is connected to ground, red to power and white to the green EIS Aux input.

Fuel System – Firewall Forward

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Two fuel lines pass through the firewall.  One is from the electric fuel pump,  the other is gravity feed. In the picture below the right line comes from the electric fuel pump. The inline check valve ensures fuel can only flow towards the engine. 

Fuel lines at firewall
Fuel lines at firewall

After the check valve is a tee, shown below. Left side connects to the electric fuel pump check valve,  right to mechanical pump check valve and the top goes to the carburetor.  Behind the tee is the inlet for the mechanical pump.  It’s fuel line is connected to the left line in the picture above. Rest assured, the top hose now has a clamp, it was not installed when I took this picture.

Tee connecting both pumps
Tee connecting both pumps

Below you can see the mechanical fuel pump on the right.  The outlet connects to a check valve that’s connected to the tee. I wrapped some silicone tape around the check valve so won’t chafe nearby components. 

Mechanical fuel pump connections
Mechanical fuel pump connections

The outlet of the tee connects to the fuel inlet banjo on the Dellorto PHBE34BD3 carburetor. 

Carburetor fuel line connection
Carburetor fuel line connection

This is one complaint I have about the Hirth F-33, it came with the fuel pump and carburetor.  The outlet on the fuel pump is made for 1/4″ (6.3mm) ID hose but the inlet on the carburetor is only 6mm. To resolve this I ordered a new fuel inlet banjo, Dellorto part number 6273 that has a larger diameter barb.

Dellorto banjo 6475 (top) 6273 (bottom)
Dellorto banjo 6475 (top) 6273 (bottom)

Now all I need to do is fasten the fuel tanks in the wings and install the air filter and she is ready to run!

Fuel System

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I’ve spent many hours researching and thinking about the best way to design the fuel system. Originally I planned to use the five gallon fuselage tank that came with my kit. But after deciding to register my airplane instead of going Part 103 I decided to add wing tanks. It would have been nice to use the fusealge tank as a header tank but the fact it interferes with my toes when working the rudder pedals I decided it would be best to remove it. Maybe I can build a custom header tank that does not hit my toes but for now I decided to move forward without it.

Toes caught on fuselage tank support
Toes caught on fuselage tank support

Starting at the wing we have the valved quick disconnect. I used a 90° male end to keep the hose along the fuselage side.
Directly after that are the fuel filters. This location is easy to access for service and inspection.

Fuel filter and wing quick disconnect
Fuel filter and wing quick disconnect

I still wanted some sort of header tank to ensure the fuel pumps won’t suck air when I’m banking and the tank is not full. The simplest solution to this was to add an inexpensive one quart tank for each wing tank. 

1 quart tank
1 quart tank

These were originally designed for radiator overflow and came with a small vent hole that I sealed with some heat.

The bottom of the tanks are routed to the right and left input of the selector valve. This valve is from a jet ski, easy to find so it can be replaced periodically before it fails. It only provides left, right and off positions. For midwing airplanes, like mine having a both position could result in the pump sucking air from an empty tank instead of fuel from the full tank.

Silicone tape to protect fuel lines from chafing
Silicone tape to protect fuel lines from chafing
Fuel lines connected to selector valve
Fuel lines connected to selector valve

After the valve is a tee, each outlet is connected to a different fuel pump. An electric pump and a mechanical pulse pump on the engine. I mounted the electric pump in the fusealge right after the valve. 

Some day I’ll need to drain all the fuel so I can replace fuel lines, valves and to service the fuel filters. The outlet of the electric pump connects to a tee, one outlet towards the firewall, the other to the Curtis drain valve I installed on the bottom of the fuselage.

Tee to fuel system drain valve
Tee to fuel system drain valve

Mounting the valve was simple after making a retaining bracket out of some plywood and a piece of RS-7. The bottom plywood is made from 1/8″, this is needed to lift the brass piece off the floor to leave room for the hose clamp.

Retaining bracket for fuel drain
Retaining bracket for fuel drain
Retaining bracket for fuel drain
Retaining bracket for fuel drain

The RS-7 was cut so it fits around the brass piece and then some 1/16″ ply was added as a top.

Retaining bracket for fuel drain
Retaining bracket for fuel drain

The round part on the brass is 0.550″, I used a 1/2″ forsner bit and a file to make the hole. I placed the brass piece in the hole and slid the retainer over the brass to through drill the two mounting holes.

Next I used a small file and made a notch from the body hole to one of the mounting holes.

This will allow the Curtis valve to fit through the hole.

The retainer is slid over the valve and mounted in place.

Some of these pictures were taken before I tightened down the drain valve into the brass. Before I did that I coated the threads with Permatex Aviation Form-A-Gasket to help ensure I have no leaks.

Added some washers and lock nuts and the drain is ready for use.

Fuel drain valve
Fuel drain valve

The nice feature of these valves is that they have a mating drain hose that locks onto and seals against the valve so you can drain without spilling or dripping fuel.

Fuel drain valve with locking drain hose attached
Fuel drain valve with locking drain hose attached

To speed up draining just turn the Facet pump on, using the selector valve you can select what tank to drain.
I used some copper pipes to make the penetration at the firewall. The reason I did this is for safety. If there is ever a fire in the engine compartment the blue fuel line will melt from the heat and I’d have fuel leaking by my toes near a fire. The long copper lines will take some time to transmit heat from an engine fire all the way back to the blue lines. 

Fuel lines to firewall
Fuel lines to firewall

Tank selector valve and pump plumbing
Tank selector valve and pump plumbing

I’ll cover firewall forward in a future post.