Page updated on: October 3, 2009
December 7, 2009
Chapter 13 - Nose, Nose Gear, Pitot, Rudder Pedals and Brake Master Cylinders
Chapter Overview
In this chapter, I will build the nose gear box which contains the nose gear strut and the retraction assembly. The nose box consists mainly of two glass/foam/glass side panels with built-in hardpoints for mounting the nose gear hardare. At the aft end, the side panels are mounted on F-22. The nose bulkhead, F-0, is mounted at the forward end. The nose floor and side pieces are constructed of urethane foam, epoxied in place and then glassed on the inside.
In a deviation from the plans, I am installing the Jack Wilhelmson electric nose gear. This will require one additional hole on one side of the NG30.
Another change is using Jack Wilhelmson's MKNG6 nose bearing. This bearing has been engineered to minimize the wear caused by the strut. On the standard bearing, this wear has led to the nose wheel wobbling. Jack's uses a tapered bearing that is a tighter fit and minimizes wear.
The pitot-tube piping and rudder pedals are then installed. The top foam piece is then in place, the outside is carved to shape and then glassed. An access door is cut in the top (a second door for the ballast comparment is optional) and removed to fabricate door falnges. The bottom of the nose gear box is closed off by installing a strut cover and a nose wheel well.
The brake master cylinders are installed to the rudder pedals. This is going to require quite a bit of thought as I'm using the Matco brake master cylinders and they are different from the plans master cylinders. The toughest part is making sure there is a 2.5:1 mechanical advantage to ensure there is enough braking power.
Step 1 - Reinforcing the Fiberglass Nosewheel Strut
The NG1-L strut is a high pressure laminate of S-glass uni-directional rovings. Although tremendously strong, it can be delamintated (split) by extreme bending loads. It is therefore necessary to wrap it with 2-plies of BID to protect it against splitting and to give it added torsional strength.
Measuring and cutting the strut to the proper length.
The pieces of paper board seen between the strut and the MKNG6 were used to determine the number of additional plys of fiberglass needed to make a snug fit.
Step 2 - Fabrication of the NG-30s
The NG-30s are the sides of the nose box. They will be made from H100 PVC foam and fiberglassed. Hard points for the nose gear and the nose gear retraction system will be installed prior to attaching it to the fuselage (F-22).
DESIGN CHANGE (From Cozy Newsletter #86; July 2004; Page 11)
Click the above drawing for a larger view. NOTE: The text above the drawing says the additional two plys should be "BID", however, the drawing shows them as "UND". "UND" is the correct one to use.
This step was time consuming, but easy to do. The hardest part was figuring out the location of the additional hole for the Jack Wilhelmson strut. The plans method has one less hole for mounting the nose gear retraction mechanism on one NG30 than on the other one. The plans method of determining the location of these holes was to use the NG51 as a template to mark their location. However, I do not have a NG51 as it is not needed when installing the Jack Wilhelmson electric nose gear. If you look at the pictures below, you will see that I copied the NG51 from the M-drawings. However, the NG51 is missing one hole. I had to overlay Jack's mounting plate to optimize the location of the missing hole.
One area where a lot of builders deviate is making the hard points for the nose gear retraction mechanism. The plans have you cut out around 30 individual circles of BID and 15 oval pieces of BID to make the hard points. Many builders make a single large rectangular block of fiberglass. Then they use a hole saw to cut out the individual hard points and pop them into the appropriate locations on the NG30s. I felt this would be a bit of extra work, so I just used the plans method. It didn't take very long to cut out the BID hardpoints. I did it while watching a TV show.
This is the foam for the NG30. Note that I forgot to radius the inside corner. I corrected this by gluing in a small piece of radiused foam before I fiberglassed the NG30.
I'm ready to fiberglass. The fiberglass is rolled up at the bottom of the picture. Also, if you click on the picture to get the larger view, you can barely see the radiused foam I added to the inside corner of the NG30.
Another shot of the NG30 ready to be fiberglassed.
These are the mounting brackets for the Jack Wilhelmson electric nosewheel retraction system.
The holes closest to the top of the picture were drilled by me. I matched drilled them at the same time I drilled the holes for the hardpoints in the NG30.
This is the NG51 template I made from the M-drawings. Note the additional hole. It is the one with the waterline and fuselage station marked on it.
Here you can see the template with the mounting hardware on top of it. Note the holes match. Of course they do as the two center holes in the mounting bracket were drilled at the same time as the holes in the hard points were drilled.
The completed NG30.
Step 3 - Installing the Jack Wilhelmson Electric Nosewheel Assembly
Details of step will go here
Step 4 - Installation of the NG-30 Box Assembly on the Fuselage
Details of step will go here
Step 5 - Nose Floor and Sides
Details of step will go here
Step 6 - Installing the Rudder Pedals
Details of step will go here
Step 7 - Installing the Master Brake Cylinders
Details of step will go here
Step 8 - Completion of the Nosegear
Details of step will go here
Step 9 - Piping the Pitot and Static System
Details of step will go here
Step 10 - Closing the Top and Carving & Glassing the Outside
Details of step will go here
Step 11 - Manufacturing the Nose Door
Details of step will go here