Mounting the Transponder Antenna

Mounting the transponder antenna started out as Operation Question Mark. I asked around to find out the best way to mount the antenna, what size the ground plane plate needed to be, what cable do i need to use... etc. And I either got no answer, or a use what you got kinda of answer.

I was told to use RG-58, then later found out that RG-400 was needed, but there are limitations to distance of the cable reach and so on.

So, this is what I was able to come up with.

1. You need to mount the antenna as far away from your body as possible. The microwave radiation can do you harm... I noticed that some people mounted the antennas near their instrument panel just over their legs... I hope cancer is not in your plans!

2. There are specific choices of cable you can use for the transponder, an most are not cheap. Plan the distance you want to mount the antenna, and then do a little research before buying that cable.

3. The antenna needs to be mounted on a metal ground plane on a fiberglass glider. Cooking foil can work from what I'm told, but I used a metal cookie lid that Robert suggested that I could use.

4. You need to find a way to mount the antenna, and it's orientation.


In regards to bullet point 4, Robert stated that their are two way you could mount the antenna. Pointed up, where Airliners could see you, then, ATC might not. And then you have the reverse, where if the antenna is mounted down, ATC can see you, and other traffic might not... You decide!?

I chose to mount the antenna down, since the location was under my O2 tank, and I did not want to reduce the signal coverage.

I also found that I could use RG-400, and that a section at the maximum distance for the transponder cable was 8 feet, which placed it a safe distance, yet under the tank.

The next question, was how to mount it? I became concerned when I found that there was a Tech Note from Streifeneder on how to mount the transponder antenna. But after waiting a few weeks after inquiring about the TN, and receiving no answer, I assumed that I was worrying about nothing.

Again, I was pondering about a mount that would work. I showed Robert an aluminum mount that I planned to mount off of the O2 tank bracket, but he handed me a mold he made from wood, and stated, "do you think this would fit?"

It was a simple and brilliant design!

It required a few layers of fiberglass to make.

I made this stand overnight, and cut the mounting hole in the center. I also drilled a few holes in the stand tabs to allow the epoxy cement to ooze through and help anchor the mount.



Due to the distance and reach of where I needed to mount the stand, I knew that I could not reach far enough into the fuselage to hold the antenna, and screw it into the ground plane plate. I would need to mount the plane and antenna first and then glue it into the fuselage.

(You might notice, that I have the antenna mounted down... I hope ATC sees me.)

I applied a thick layer of thickened epoxy to the mount tabs, and then placed the completed antenna and mount into the fuselage. It required some weigh to be placed on the tabs and antenna top to hold it in place while the epoxy cured.

With the antenna mounted, I terminated the end of the RG-400 with the correct BNC connector, and carefully routed the cable though the fuselage to prevent any sharp bends that could compromise the structure of the cable.







The trick now is to be able to attach the other end to the transponder in the panel.

Creating a new Instrument Panel - Part 3 - Finally!

The panel is done!

After waiting a year for the radio, I had all of the parts to finish the work I started over two years ago!

The assembly was quite simple after working out the design and then successfully cutting out the holes.

The first step was to locate the area that the pneumatic tubing and wires would come into the panel tray.

The terminal block was placed close to the junction of the entering wires. The  transponder encoder tray was then mounted to the base of the panel tray.

To gauge the measurements of the wires and tubing, I mounted the instrument, switches, and fuse holders in place. 

I used Winter vinyl tubing for the instruments, and the 5-way connector to manage the tubing. The hose clips provided with the Trig transponder were a great solution to prevent the tubing from working out. I found the same style clips at NAPA.

I then wired the electronics. 

When this step was completed, I tested each component separately to verify that they work.

I did a test fit of the panel tray (minus the radio) in the glider. It was manageable.

Robert suggested that I do not use COAX pigtails to connect the radio and transponder antennas. The only trick is getting the transponder cable connected first, and then reattaching the encoder DIN connector.

(this photo shows how far I am with the cockpit, more to be covered in another post)




I remounted the radio and using a Brother P-touch thermal label maker, I created the placards.

Robert suggested that I put the Libelle logo on the panel. I recreated the logo on clear adhesive material.

After two years, the panel is finished and ready to be mounted back into the glider.


Here are the before and after photos of the panel.

       


Before


                           

                                   After






We are getting closer!....

My deadline on getting the plane to Robert is the last week in May!

Creating a new Instrument Panel - Part 2 - The design and cutting holes!

Design of the new panel

My original plan was to avoid issues with magnetic deviation on the compass, (thou it will still needed to be turned professionally), I tried to keep all of the pneumatic instruments between the electrical driven instrument's, and the compass. But after a number of test layouts, I still found myself putting the switches and fuses near the compass. I know that when the Borgelt Vario was turned on, the compass deviation was the greatest.

I took this drawing to Albuquerque Reprographics to have a pattern copy made to be used as a cutting template for the instrument layout.

There were some slight relocation of the instruments based on the size of their cases, but the finished panel would look similar to the drawing.

I was able to cut the openings using a 57mm, 70mm, and a 80mm hole cutter. the trick to get an even cut is, the panel face needs to be secured flat, and the cutter needs to be spinning fast and then slowly lowered to the panel face. I'm sure it would have worked better on a drill press, but I had to do this by hand.

I then applied a spay coat of my DCC cockpit gray, making sure that the face had a matte finish, you don't need any glare coming off of a glossy panel!

Next post will cover the wiring of the panel.  ... This should be fun!

Ouch!, my back hurts

Streifeneder came through again!

A few months ago, I wrote to Streifeneder about acquiring a replacement seat back. After spending a great deal of time cleaning up the old seat back, I found that after I removed the old polyester material, I couldn't determine what was the correct shape.

In January, they wrote me about finding a seat back. I was delighted!, I didn't need to waste anymore time on the original ,"Old and Busted" seat back.

The new seat back arrived in no time and I was surprised to see how much material was missing on the one I originally had.

  

The old seat back after sanding weighs 553 grams, while the new seat back (on the left), weighs in at 674 grams before painting.

 









What you cannot see in the photos is the thick rounded edges on the new seat back, while the old one has little or no rolled sides.

The replacement seat back required little work to get it prepped for painting. The were a number of bubbles and voids, but they were easy to fill.

I used a lacquer based primer, then sanded the seat back smooth.

I sprayed the seat back with DCC gray paint, that matched the cockpit.

We're moving now! ....... Instrument panel, plumbing wiring,.... install those parts!

New view, New Canopy! Part 2

The next few post will be "playing catch up" on what was done over the long winter months.


Clean up and filling the holes and gaps in the frame!

The plan, as I mentioned earlier, is that I would like to paint the frame, since it looked grungy.

The voids, gaps and holes were filled with an epoxy resin mixed with the cotton flock.  After it cured, I sanded down excess resin.





I used a gray primer paint to fill the fine pits and then used a fine sand paper to even the surface.

The next trick was to replace the latch. I repainted the forward portion of the frame before re-attaching the latch.

I created a jig to hold the frame up, and then with the use of a hot glue gun, I tacked the forward edge of the frame to a board, this will prevent it from shifting,while the resin cures.

I replaced the steel pin in the latch, and created a tape and wax seal around the latch to prevent any resin from seeping into it.  Next, I used my favorite resin mix of cotton flock, and pressed the pin back into place. I worked the resin into the void slowly to prevent any bubbles of air getting trapped. as soon as I acheived the desired level, I placed peel ply over the filled in spot.

After the resin cured, I placed a thin layer of glass cloth over the repaired opening.





After the final cure, I did a test fit of the latch on the fuselage to ensure that I was able to securly close the canopy.

I needed to remove excess resin humps on the latch pin areas, but after that was done, the latch worked perfectly.

The frame is ready to be painted.
 

To protect areas that I don't what paint to hit, I covered the latch with a disposable showercap and taped it securly., I also taped the frame pins and alignment tabs.

The frame was then painted with the DCC gray paint used in the cockpit.




Now that the canopy frame is finished, I'm off to finish the seat back!

Two years into this project!

Two year to the day that I have been engrossed and obsessed with my unfinished glider. Where has the time gone?

What was done over the second year of work?

The gelcoat was finally removed completely, and the trailer was torn down, sand blasted, repainted, and dropped off to the trailer shop to have the floor boards replaced, re-skinned and a full clam shell lower frame and hinge fabricated. But the cost to do this was higher than the original estimate, and the trailer spent most of the year sitting at their shop until I could afford to pay for the balance of the work that was done, and what is still needed to complete the clam shell lower frame.

I need to mention that a project like this is like all hobbies, it requires money to feed it. I have been on a limited budget that has hindered my ability to move forward at an accelerated pace.
Like last year, we had an early hard cold winter that slowed my progress. But during the winter, I was able to finish painting the cockpit, bulkheads, and seat (to be covered in a future post). I was also able to finish the spar dollies and one mid-wing support (to be covered in a future post).

With tax time around the corner, and hopefully a decent return, I can complete much of the more costly additions, (the radio and O2 system).

 Here is a photo of the parts installed in the cockpit today, and a test fit of the fabric pads.









 
















In the months to come, the plan is to complete the installation of the internal components and deliver the glider to Roberts shop to finish the surface cleanup and finally get some paint back on her,

Thank you for those who have been following this blog.

On the rails!

Part of the fuselage repairs included the rebuild of the canopy track rails that run along side of the cockpit top frame sill.

My Libelle's tracks were chipped and worn down. I was concerned on finding a workable method to achieve the look of the originals.

I decided to try a test on one side, and not completely down the sill.

I used the aluminum duct tape and burnished the tape along the sill and up the edge of the remaining rail. The tape, when handled carefully, makes a straight, flat edge for the resin paste to sit on.

Next, I rotated the fuselage on it's side so the epoxy resin would stay along the old rail edge

Using epoxy mixed with my favorite material (cotton flock), I troweled in the mixture, carefully along the side of the old rail, and feathered the edge into the tape.  


After the resin cured, and I removed the tape, and I found that this method would work.

I was ready to do a full side.

The setup for the right side of the fuselage cockpit sill was the same as I did with the test side.

Next, I used the same mixture and troweled it down the full side.

When the resin cured, I removed the tape and started the clean up with a heavy grit sand paper.

To ensure that I removed the correct amount of waste, I measured the depth of the groove in the canopy frame and made a depth gauge.

I then used a finer grade of sand paper to even out the new rail to the correct shape and height. The gauge verified the correct height of the rail.

The new rail will need some light filling, but for the most part, they are finished!









The sill needs some additional cleanup before the final paint job.

It's time to start putting eveything back into this bird!