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Tuesday, August 25, 2015

Nose and nose gear - part 30

Hinge box (11.3 hrs)

One pretty common complaint heard in Long EZ circles is that of cold legs. A couple of reasons for this are the inability of the typical heat exchanger to send warm air from the rear mounted engine all the way up to the nose of the plane, and the air leak prone nose compartment.

Over the years builders have come up with all kind of creative solutions for this common issue. My approach would be to seal up as many holes as possible first, then worry about possible heating options.

Looking at the upside down nose of my Long EZ, one obvious source of unwanted high pressure air is the nose gear hinge area. The gaping holes left there look capable of delivering cold air right on the pilot’s legs.

"Dang, you can almost see the back-seater from here! "

My friend Beasley had a very interesting approach to sealing this area, by using a small forward-hinged spring-activated door in front of the hole. 

The forward hinged door is able to slide on the strut cover as the gear leg moves

His approach was made possible by the omission of the foam wedge that went right in front of the nose gear hinge. 

This foam piece is a faint attempt at closing one of the gaps

Since I had already installed it, I had no real good place for a hinge, and had to think of a different solution. One thing I couldn’t understand was the reason for the hole to begin with, so I thought about sealing it shut from the inside.

Grabbing some ever present scraps of foam around the EZ shop, I whittled them until they fit.

Getting the foam scraps to the right shape

Foam scraps closing the hinge hole

One other advantage of this modification, was the boxing on the fifth side of the forward space between NG30s, leaving a small enclosed space that could be handy to store a few tools, or a spare tube.

Foam scraps as seen from inside the nose compartment

I removed the foam pieces, glassed them on both sides, and tested them again.

Proceeding with the modification

After more fitting and sanding

I'm starting to like where this mod is going

At this point I reinstalled the nose gear, and finding no interferences anywhere, I went on to the installation phase.

Behind the microscope LED light, the Dremel is removing foam and micro for a flox corner joint.

Given the small confines, the Dremel was used extensively in this area.

Foam and micro were also removed on all four sides of the horizontal piece

Three sides were filled with flox, then the piece was inserted carefully in place

Same piece curing, as seen from inside the nose compartment.

The next day I added BID tapes just to secure this first piece, and make sure there would be no gaps for air to get through.

Small BID tapes

Sealing the horizontal piece

Same thing one day later

After flipping the fuselage right side up, I started working between the NG-30s.

Getting ready for a flox corner

Flox sandwich

To be cleaned up

Tying things together

Peel-ply over BID

In the morning, after a little cleanup.

No air is coming through here

My feet would have rested right next to the drafty hole

So, one might ask... What's the point of sealing the holes by the hinge when you can clearly see another gaping hole right behind it?

"Yeah... what about that hole!"

You would be talking about the hole through which the nose gear actuator operates. 

Well, you've got to have that hole. 

The good news is that the flange I added to the front of the entire nose strut will completely seal this area in flight when the nose gear is retracted. I might get a little indirect air for a couple of minutes on takeoffs and landings, but I can live with that. 

I have more ideas on how to seal the remaining space between NG-30s in a way that will not impact the actuator mechanism and still be removable for maintenance, but we'll leave that for later down the road.  

Nose gear hinge "box"

It's a tight squeeze in there now

Looking toward the right NG-8

I'm very happy how this mod turned out
The struts operates just fine, and the cold air shall remains outside.
Before and after

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