Tandy's Sailplane at the Concours

The magnificent Goldberg Sailplane.

I received this picture yesterday a fellow modeler that took this picture of my 1940 Comet Sailplane at the Society of Antique Modelers (SAM) Concours event in Muncie, Indiana, last Wednesday evening. My competition results are shown below.....................Tandy Walter- Arlington, TX

Solution to Sailplane Exhaust Extension Problem

My good friend Bill Taylor, who lives up in Tulsa, Oklahoma, built his Sailplane shown below before I built mine last year. Bill was the guy who sent me his exhaust extension design when I was building my Sailplane. Bill developed his extension design for his Ohlsson 60 based on formed sheet brass stock, which was solder together with hooks on the side for spring retention. The design worked perfectly for his Ohlsson 60 installation. So he naturally used the same design when he built his Sailplane powered with a McCoy 60. Due to some health complications and schedule activities, Bill had never had the opportunity to run his McCoy 60 until last week.

During Bill's test runs last week, his McCoy 60 generated so much more exhaust heat than the Ohlsson 60 that it melted the solder and the brass exhaust extension fell off the McCoy engine! After Bill redesigned his exhaust extension using mechanical fasteners, he sent me a letter advising me of this problem along with the sketch below detailing his design modifications. As Bill said, if the extension were to come off during the power climb, the cowl would most likely catch fire and burn up the Sailplane in flight! :O<

By the way, Bill said his McCoy did not overheat running inside the cowl! :O)

First of all, thank you Bill. You may have very well saved my Sailplane from a fiery end. I have used Bill's ideas with a little twist of my own. I selected .025" piano wire and bent up the two hooks shown below. As you can see, I put a "Z" bend on the ends that hook to the sides of the extension.
After unsoldering and removing my original hooks, I inserted the Z-bend into a hole in the side of the extension and used the spring jig shown below to position the hook while it was soldered to the extension.
This is a close up of one of the soldered hooks. Even if the solder softens due to the exhaust heat, the Z-bend has the hook locked in place under spring tension.
Next, as per Bill's suggestion, I drilled two holes through the extension's soldered lapped seam and inserted two 2-56 cap screws made up with lock washers and nuts on the inside of the extension.
This picture shows the two lock washers and nuts on the inside of the brass extension that were easily tightened down with a small ignition box-in wrench. If you look close, you can also see the .025" Z-bend wires pointing forward inside also.
If you look closely in the picture below, you can see the spring that holds the brass exhaust extension in place on the Mcoy's exhaust stack...............................Tandy Walker

Goldberg Sailplane videos

We're still waiting on Tandy Walker's Sailplane. In the meantime, here are some built by other modelers.

159 Sailplane Today's Progress on the Final Assembly

Report #159 from Tandy Walker on the construction of his Comet Sailplane for the 2009 SAM Champs in Las Vegas

Comet Sailplane Project

The picture below shows the integrated ignition unit consisting of (1) a 750 mAH NiMH battery pack, (2) a ModelElectric coil, and (3) Marv Stern's Aero Tech IGN-SW ignition module installed on the back side of the Sailplane's firewall with two 2-56 cap screws. You can see the (+) ignition pack charge terminal and the (+) booster terminal wires with lugs soldered to their ends. In addition, the landing gear has also been installed.

With the two wire lugs attached to the terminals on the back side of the hatch cover, this picture shows the two external terminals and the hook up for charging the ignition pack and attaching external booster batteries (note that the landing gear wire is grounded to the engine).
The green wire in the picture below is the landing gear's ground wire to the engine for the booster and ignition pack charge grounds on the landing gear shown above. I was doing a continuity check with the multimeter that you see in the picture.

This picture shows the ignition unit's ground and point wires. Notice that the high tension lead is too short to be routed up through the cowl and to the spark plug.

So I started making a new high tension lead. Larry Davidson sells the clip shown below that snaps onto the coil post. Years ago Dick Huang gave me bunch of very small aluminum brads that I use to attach the high tension wire to the coil clip. About a 1/4" of the insulation on the high tension wire is removed and the stranded wire is bent through the hole in the coil clip. The aluminum brad is also pushed through the hole and then flared out, which attaches the high tension wire to the coil clip. Black heat shrink tubing is used insulate the connection as shown below.

James Lollar is sending me some 1K and 10K resistors to use inline with the little spark plug clip that I make, but they have not arrived yet. I will probably use a 10K resistor and locate it as close to the spark plug as practical. Well, that it for today.........................Tandy

Spraying Klass Kote on Sailplane's Wing

This afternoon I made up an all new mix of satin Klass Kote and shot the bottom of the wing around 1:30 p.m. Later on this afternoon, I decided the wing would be dry enough to spray the top. So around 5:00 p.m. I shot the top of the wing. When I had finished spraying the top, I took the picture below before the atomized Klass Kote epoxy particles had settled out of the air in the closed garage.

A little later when I went out and checked on how the wing was drying, I took this picture in an attempt to show you the beautifully smooth satin Klass Kote finish on the top of the wing.

I want to share with you a problem I encountered with the satin Klass Kote. Remember last Friday I sprayed the bottom of the stab. Since I let it dry overnight, I sealed the remaining 6 ounce Klass Kote mix in a jar and put it in the refrigerator. Saturday morning I removed the mix from the refrigerator, gave it a couple of hours to come up to room temperature, and then added just a touch of reducer to help thin the mix. I took the time to thoroughly stir up the mix. Then I mounted the stab on the second support fixture and sprayed the top of the stab.

Here is problem I encountered: As late as yesterday evening the dry coat of satin Klass Kote on top of the stab was not as satin as the rest of the model's components #$@&? (it had kind of a shiny or semi gloss sheen). The only thing I can come up with as to why is that the mix had been placed in the refrigerator overnight and it had a little additional thinner added, which by the way according to Nate Dickerson was supposed to be OK.

I kept looking at the top of the stab and debating about what to do for a long time. Since I was never going to accept this miss matched sheen of the top of the stab, I remounted the stab on the second support fixture and resprayed the top of the stab this afternoon in between the time I sprayed the bottom of the wing and the top of the wing. As you can see below, by respraying using the fresh satin Klass Kote I had mixed up for the wing, the satin finish of the top of the stab now matches the rest of the model's components. I will call Nate Dickerson (Mr. Klass Kote) tomorrow and see if he knows what the problem could possibly be.

Now I will take my time and spend this coming week going through all of the final installations and assembly on the Comet Sailplane. I will perform a weight and balance to check for meeting the SAM minimum weight requirement and to check for the proper CG location. So I will have a couple more reports to send out before I begin the Sailplane's all important flight test program. But at least I am finally finished with all the covering, painting, and finishing activities!..............................Tandy Walker

Klass Kote on Comet Sailplane II

This morning, I sprayed the top of the stab with one coat of satin clear Klass Kote and brought it in and sat it on the model room work table for 24 hour drying as shown below. One point I want to make is that very little if any overspray got on the top of the stab from when the bottom was sprayed yesterday. This will also be the case for the wing as well.

An awfully lot of thought was put into how to hold the wing for spraying. The final solution came out unbelievably simple as shown below. Two fresh rolls of Viva paper towels were tied across each end of a long box with string as shown below. A folded rag was placed on top and at the end of each roll for trailing edge shims also shown below.

The Sailplane's wing was place upside down onto the rolls. The wing was gently pushed down into the rolls to form a kind of depression for a pseudo cradle as shown below. Then the air supply was attached to the empty spray gun and mock spraying was done to see if the wing was going to move under the spray gun's air pressure. The wing was as solid and did not move or rock at all.

Then the wing was turned over and placed onto the rolls without the two rags on the end as shown below. Again the air supply was attached to the empty spray gun and a mock spraying was done to the top of the wing to see if it was going to move under the spray gun's air pressure. Again the wing was as solid as rock and did not move at all in the upright position.

This is some good general information for spraying any big wing. Anyway, tomorrow afternoon I will get set up and spray the bottom of the wing first and then the top on Monday.......................Tandy