Day 4--our 2-in-1 airplane, slick wings, & a battery

Hello everyone!

Today was a big day for the wings--the right wing is finished and ready for aileron and flap installment, and the left wing is right behind it with only about 3 hours of work left to go.

In addition, today we saw the nosewheel and tailwheel go on the aircraft.  That's right...we have a nosewheel and a tailwheel--say what?  Well, the Sportsman is a configurable airplane.  If built for it in the factory (which we are doing), the airplane can be easily converted from a tricycle-gear airplane to a taildragger in a couple of hours.  Configured as a tricycle gear, the airplane is statistically safer to land, maneuver on the ground, and train with in general.  As a taildragger, it is better for soft & short fields.  Our plan is to fly it initially as a tricycle gear to get accustomed--but the finished product will be a taildragger.

Right now it looks pretty funny, though--it's got a nosewheel, and a tailwheel--but no main gear at all yet.  We'll be there soon!!

Today I'm changing it up...we've spent so much time riveting the past couple of days I thought I'd share a little--here's a 20-second video of T"racy" the riveter in action on the left wing skins:

We left off yesterday with a wing having clamps all over it.  This is the finished product of the cove--at the very corner there you can see the 'doubler'--a thin metal strip in the glued-together sandwich.  Adding the extra layer of metal increases the strength where the cove skin meets the top skin.

Today I got to do the interior wing work on the left wing that Tracy did yesterday on the right wing.  This is a pneumatic pull-riveter in action waaaay down the aux fuel tank hollow.

This is the last time i hope to see the fuel tanks outside the wing...but if maintenance is required, they are removable.  It will take some rivet-drilling and time.  The primary tank is up close.  You can see the fuel lines (metal piping) in between the main and aux tanks.

Once the fuel tanks are in, then the lines go in.  This is one of two vent lines going into the primary tank.  The red cap in the upper right is where the fuel line (metal pipe) is about to go.  Putting these in required getting a forearm through the 4" inspection holes in the wing...tight.

These are the two vent lines coming out of the wing.  The vent system is simple but ingenious.  One line simply connects the aux and main tanks; this equalizes the pressure in the two wing tanks at all times.  The other line goes from the primary tank out the metal piping protruding from the bottom of the wing.  This keeps all venting to a single exit point (instead of one vent per tank).  The wing will eventually have a carbon fiber cap on it which will give the wing a clean aerodynamic finish, and also house our Navigation lights, Strobe lights, and Landing lights.  It will cover the vent tubing.  The electric wire for the lights is coiled up on the right of the picture by the leading edge.

We also finished the trim tab work on the horizontal stabilizer today:

This is the fist pic of our horizontal stabilizer.  Bryce is working on the trim tab. Matt is in the background working on our tailwheel.

Bryce ran the elevator trim motor with a 9-volt battery to test the travel limits.  we adjusted it to tech order travel with the jam nuts on the pushrod.

Last, here are a couple of shots of our weird gear configuration!

Here's the nose gear hanging on the airplane for the first time.  It is not steerable--you have to use differential braking to steer on the ground.

Tracy took this shot of me using a torque wrench to set all the bolts on the nose gear to the correct torque.  There are torque-specific bolts all over the plane.  Not enough torque and the bolt could back out.  Too much and it could shear the bolt.

Here is the tailwheel on the airplane.  Unfortunately, we didn't get to do any of the work on this.  Putting a tailwheel on the Sportsman requires some fairly detailed fiberglass work to beef up the tailcone structure (which is all carbon fiber).  The interior of the tailcone gets fiberglass layering on top of the carbon fiber, which adds strength and better flexibility.  Eventually there will be aluminum shims under the leaf springs you see here, helping the tailwheel conform to the fuselage shape and keep impact loads off the tail.

This is looking from above into the tailcone.  You can see the fiberglass layup at the bottom of the pic (tail end of plane).  At the top of the pic (bulkhead E), there's a massive nutplate with 8 bolts in it, all fiberglassed into the structure.

Here's a closeup of the nutplate.  Getting this to the exact right shape to be structurally significant is a challenge...I think that's why we haven't done it yet!

Okay, that's all 'til tomorrow.  It's possible that we might get the main landing gear in tomorrow--but it is Airshow day at Arlington so we'll see.  Happy Friday everyone!  -zen

Day 3--Left Wing Finishing, Motor mount, & surprises!

Hello Everyone!
By the Two Weeks to Taxi timeline, we are now 25% of the way to our first taxi and about two weeks from the first flight of our airplane!!  After today, we are actually a couple of hours behind, but nothing we can't make up.  Today was again filled with new experiences (trend item!) as we finished the left wing and mounted the engine to the fuselage.  In addition, while we were working some things magically 'appeared' on the airplane...we had to scurry to find the folks who put them in so we could see how things are done.  Here's the wrap-up!

First, here's the progress on the left and right wings:

This morning we put the right wing up in the rivet room next to the nearly-riveted left wing.  Immediately after this photo Ryan put the upper skin surfaces on the right wing and prepped them for riveting.

This is an example of my sometimes not-so-Zen-like qualities...didn't put full pressure on the rivet head prior to depressing the trigger.  The rivet bucked in the back but obviously isn't flush in the front.  This hole had to get the bad rivet drilled out and a new one put in.  For the record, Tracy's current pneumatic rivet score is 100%...no errors.  I married up.

Left wing right before it came off the jig--skin rivets complete!  I didn't count them.  There are a lot.

This picture clearly shows the different between flush rivets (top) and universal head rivets (the nubby ones below).  In this case the flush rivets are for aerodynamics over the leading edge of the wing.  The black circles are rivet holes that were filled with clecos until the final riveting.

Once off the jig, the next step is to put the "cove skins" on the wing.  The "cove" is at the trailing edge of the wing and it's where the flap fits (inboard) and the aileron fits (outboard).  If you look at the curve of the metal, it looks like it seats the leading edge of another wing--which it does, sort of.  Our flaps and ailerons are each shaped like small wings of their own.  When retracted they fit into the coves with minimal clearance, helping the airflow over the wing.

One of the interesting things about securing the Cove skins: they're actually glued to the top wing skins, not riveted.  The glue is Loctite epoxy, which is nasty stuff (hence the gloves and respirator) but should seal the trailing edge from moisture.  Check out all the clamps--only 1/4" gap between them to ensure a tight seal.  The epoxy takes about 3 hours to dry...so we will remove the clamps tomorrow.

I missed a picture of the fuel tank going in, but hope to get it on the Right wing.  In this picture the fuel tank is already in with the fuel lines run, and Tracy has almost finished riveting in the wing root rib.  The cylinder in the middle of the tank is the electronic fuel gauge--you can see the grounding wire coming out of it.  The fuel from this tank (the primary tank) comes out of the lower-most, silver-dollar shaped hole.  It's gravity feed so the airplane doesn't depend on electronic systems to get fuel to the motor.  Genius.

On the contrary, fuel from the outer wing tank (the auxiliary tank) has to get from the outboard of the wing through fuel lines to the main tank.  It does this with an electric fuel pump (above), which Ryan put in today along with the fuel lines.

Today was also Engine mounting day!  There's a lot of small but time-consuming work to be done on the engine during the mounting process:

First, the engine mount!  This is one of the first things Tracy did this morning.  Note the four big holes on the front end--these are the mounting points.  Unlike a car, you don't mount an airplane engine from all the way 'round--only the one side.  Therefore, the mounting points are reinforced and the engine/prop balance has to be perfect.  Those tight tolerances are one of the driving factors for aircraft engine price.

I caught Matt studying the manual for our motor--good on 'im.  With most of the work we're doing, the techs have the steps memorized, so they don't reference a checklist during a step--only at the end of the step, to make sure they didn't miss anything.  In this case, Matt is being more deliberate because of the various motor types to go on the Sportsman.  He is 'de-pickling' the engine and getting it ready for Sportsman-specific applications.

One of the Sportsman-specific applications is this gold-colored heat shroud that Tracy put over the main fuel pump this morning.  In some aircraft the airflow inside the engine cowling might be enough to keep the fuel pump cool--apparently not so in the Sportsman.

Check out the detail in the safety wire.  Today we learned that when safety wiring, you have to check: direction of twist, number of twists per inch (varies by application) and bend direction.  Note that if anything pulls on the safety wire, it will pull in a clockwise direction--tightening the bolt.  Ben demo'd this safety wire and it took him a good 10 minutes to put it in.

Mom, you asked how to get an engine on an airplane--here's your answer!  The engine weighs around 400 pounds.  No way we're going to lift it without hoist power.

Here's a picture of the engine (gold) on the mount (grey) with the massive shock-absorbing bushings (black) on both sides of the mount.  The bushings look almost the same but are not.  The right one is a "compression bushing" which is designed to dampen the compression forces as the motor pulls on the bolt head/washer.  The bushing between the mount and motor is a "tension bushing" which handles different vibrations as the motor tries to pull away from the mount.  On the bottom of the mount, the order of the bushings is reversed (because the order of the motor's push-pull effect is reversed).

This is my exact view to the lower-left engine bolt.  The working space in here is pretty tight.  It took Matt & me about 45 minutes to get all 4 cotter pins into the 4 bolts with the correct bend & cut length on the pins.  That's longer than it took to mount the engine. 

Finally, here are some of the random additions we either worked on or had to just keep up with today!

I caught Bryce putting a radio antenna into the tail.

Here's the radio antenna from the top of the tail, right before Bryce caps it.  Since our fuselage is carbon fiber, all of our antennas have to be external.  If they were internal or contacted the carbon fiber, the signals would get distorted since carbon fiber conducts electricity.  In this case, the exterior antenna (coat-hanger-lookin' thingie) goes through the rectangular cutout through non-conductive fiberglass glue to the antenna.  the antenna cable runs down the rudder and forward through the fuselage to the avionics panel.

Another thing Tracy worked on today is the control yoke.  Our aircraft has center sticks, not a traditional yoke--but the sticks are connected mechanically by this bar, which is still called a control yoke.  So if one stick moves--they both move.

Three pulleys: Left Flap, Right Flap, and aileron (remember the aileron crossover cable from yesterday?  That's why there's only one, i think.  I'll make sure tomorrow).  One thing is certain--these are right between and directly under the front seats (between the two control sticks).

The springs on the rudder cables (up by the firewall) are centering springs--to pull the rudder (or the tailwheel in taxi operations) back to neutral after a rudder push.

This is our future rear seating/cargo area.  The entire fuselage from the first bulkhead all the way to the tail will be empty to keep the plane within center-of-gravity tolerances.

Whew!  That's a lot.  Y'all gotta let me know when this gets boring. 
On another note--the Arlington fly-in and airshow is this Friday.  In this part of the country there are a lot of vintage and unique aircraft--we saw some of them flying in today.  We should get a small break on Friday and I'll try to post some photos of the happenings around the airfield here!

See you tomorrow! -zen

Day 2--Firewall, Wing assembly, and rivets!

Hello everyone! Thanks for following along--we hope you're enjoying the pics from here in Arlington.  Let us know if you have any questions or would like to see something else in the blog, and we'll try to make it happen!

Today was another great day for learning, with more 'firsts' for each of us.  Today we learned how to use a Nico press to fasten cables, attach cables to bell cranks & pulleys, use pull rivets, drill carbon fiber, countersink holes for flush rivets, cut & bend fuel line pipes, and use swage locks.  The list goes on!  Here are some photos of the things we were working on today.

First, here are the guts of the right wing coming together:

This is one of the flap pulleys in the right wing.  Each wing has two flap cables--one to deploy the flap and the other to retract it.  The big cotter pin next to the pulleys keeps the cables seated in the groove.  The third cable sitting above the pulley is one of the aileron cables--the other one isn't installed yet.

This is the aileron "secondary" cable (the primary cable is in the cockpit--the secondary is in the wing; we will attach the two later).  It uses a similar type of pulley system.  The other aileron cable, the "crossover" cable, isn't installed yet in this photo but also goes through this pulley.  As its name suggest, the 'crossover' cable works from wing to wing in order to ensure symmetric aileron travel during flight.

This is the completed aileron cable assembly.  The cables go to a bellcrank which attaches to a pushrod (far right, protruding from the aft wing spar).  The pushrod actuates the aileron in flight.

This is a closeup of the cable fittings we use.  The clamp that looks like an oil drum is a Nico clamp.  We hand-pressed them with a Nico clamp, then put heat-shrink around the assembly to keep it clean and prevent wire frays at the end.  The Nico clamp actually creates a strong point in the cable, so it is extremely unlikely to fail.

Tracy and Ryan.  Tracy is hand-riveting the right aileron trim tab.

This is the completed right aileron trim tab.  Nice work, Tracy!  Note the inspection hole in the upper right of the photo...

...Inside the inspection hole is the electric motor that actuates the trim.  Our airplane has 2-axis electric trim (pitch and roll), so we will have a motor in the tail as well.

Our left wing already has the 'guts' in it required to rivet the top skins on, so we did about 85% of the rivet work on it this afternoon.

 

Left Wing ready to rivet.  The porcupine look is the Cleco clamps which act like removable rivets. The hole in the wing is a fuel filling port--there are two on each wing for our 4 total fuel tanks.

The rivets are covered with Rivet Tape, which serves to hold them in place and also helps keep the rivet gun from damaging the surface when it impacts.

This is the inside of the left wing looking from inboard.  On the left you can see the rivets prior to riveting--once riveted they are more flush.  About 3 feet down into the wing you can see the first spar with the lightening holes cut in it.  The first 3 feet of wing are empty right now but will eventually contain the primary left fuel tank.  Our tanks are welded aluminum and contribute to the wing's final structural makeup.

Finally, today we installed the Engine Firewall:

Tracy with Matt drilling firewall holes.

Tracy's tool is a 90deg drill--think "dentist drill."  It's used for tight spaces.  We tried to get a picture of Eric working inside the fuselage but there wasn't room for the camera...just kidding.

This is the interior side of the firewall, with insulation to reduce unwanted cabin heat from the engine.

This is the exterior of the firewall, with cleco clamps holding the firewall to the fuselage.

Eric is using a countersink cutting tool to sink the wells for the flush rivets to the exact depth.  Matt is holding a vacuum next to the process to keep down carbon fiber dust...which irritates skin and also can short out electrical circuitry if it accumulates.

This is a typical buzz of activity around the airplane...yep, that's how you do it in two weeks!

This is the near-complete firewall with the flush rivets in.  I only had to drill out one of them & redo...lucky.  The red seal you see is fire retardant caulk.

Three months preggers and building a plane--my wife is awesome.  But Tired!  See you tomorrow!