Posted by: Miguel E. Mármol G. | Jan 27, 2012

Header Tanks, Engine Mounts, and Horizontal Stabilizers

As the past couple of entries have been related mostly to systems I wanted to post something new about all the hard work that the build teams have been doing. This particular post is about their work in the fuselage of the aircraft. They have reached two big milestones:

1. installation of the engine mount and nose gear!

2. closing of the header fuel tank

3. trial-fitting the horizontal stabilizer in the fuselage

Flint and Burt using the laser level to make sure that the nose wheel is rigged properly

Engine Mount & Nose Gear

The firewall installation was a LOOOONG time coming as it required many reinforcement plies to be laid along the attachment points for the firewall…THIRTY plies per attachment point to be exact. With the SIX attachment points this adds up to ONE HUNDRED AND EIGHTY PLIES!!!! I get fiberglass itch just thinking about it.

On the average, we laid about 10 plies every build session. With two build sessions a week that meant that it took the team NINE weeks to complete all those layups. Yeap, you read that right, it took TWO months to get all of those plies in there. This grueling and tedious process came to be known within the team as “ply-a-palooza” and the team worked through it admirably even putting in a few extra days of work to make things go faster.
Unfortunately to the untrained eye this progress is not very noticeable. Each ply just increases the thickness a little bit and after nine weeks the plane looks much the same as it did when it started; with the difference that it is now way stronger.

Burt Davey as he patiently adds one more layer to the ply-a-palooza. The ruler is not magically stuck on the side of the firewall, the airplane was nose-down for this installation

After that grueling ordeal it was a matter of drilling a few holes and assembling some hardware and the entire firewall and nose gear went on the airplane. A VERY visible addition which took less than two weeks to get on the airplane.

Horizontal Stabilizer

There have been some other posts about the progress we have mad in the horizontal stabilizer construction. These last few months have been dedicated to building the elevators in a very similar process as the stabilizers.Now the big step is to fit the stabilizer to the actual aircraft fuselage.

One of the elevators with all ribs and hinge hardware installed and bonded, ready for close!

The first time we tried it we discovered that the factory-made cutouts were too small so had to enlarge them. Once we got those enlarged we were able to trial-fit the horizontal stabilizer along with one of the elevators attached. While the team working on the horizontal tail puts the finishing touches on the elevators now the fuselage team will begin the preparation for the bonding.

First trial fit...didn't fit!!!

Dan Cox, Chris Forster, and Tony Tan pose with the horizontal stabilizer as it gets attached to the airplane for the first time

Header Tank

When I published this post I forgot to add the third point that i had made at the beginning. The header tank! Right after finishing ply-a-palooza the team began to work on the header tank installation. This one is important as it will be holding fuel, is located inside the cabin, and is the only alternate source of fuel if the wing fuel tank has any issues. As such it is important to get it NOT to leak! We did this by putting extra layers of resin on the inside of the tank and being very careful to neatly seal all of the corners of the tank. We also cut an opening in the top of the aircraft and put a filler cap on there.

Inside of header tank before closing. Note the hole for the fuel cap at the forwardmost end of the tank. The airplane was acutally upside down when the picture was taken. The way it is shown is how it will look when the airplane is rightside up.

We also installed a capacitive fuel probe on the tank instead of the traditional float sensor of the sight gauge that was in the original plans. This is because they will better interface with our Dynon avionics boxes. In the header tank the Princeton fuel probe got the job done well.

Flint Jamison installing the fuel probe in the tank. The fuselage is upside down at this point.

After that installation we went on to close the back side of the tank. We will now work on sealing things nice and tight and then do a fuel tank integrity test.

Burt and Flint working on the nose gear while the back wall of the header tank dries. The blue tape is to maintain pressure for a good seal.

The wing team is only a few days away from closing the wing at this point so wish us luck and expect an update soon!


  1. […] the wing and the horizontal stabilizer, attaching the horizontal stab to the airplane, making the engine mount and nose gear and header tank, […]

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