Rather than having engines laying around on the workbench waiting for airplanes to be built, Gene built this nice display mount. All photos by Gene Pape.
Batteries, elevator hinges, motor mounts, etc.
By Gene Pape
I’ll start out by relating my journey with starting batteries.
In the beginning there were large round 1½ volt dry cell batteries. One would last about a month. If you taped two of them together and wired them in parallel they would last over a year. Life was simple and good.
Then along came war surplus NiCads. You had to mix chemicals from the drug store for them and charge them once in a while. They were smaller and handier, but they would die sooner or later. Better maybe, but not perfect.
Then along came the Fireplug. Rechargeable with adjustable power and a meter to tell if the plug was good or not. Some people still think they are the best thing ever. I kept squishing the cases so you couldn’t adjust the power and the meter would no longer work. And the cells would die when you least expected it. I lashed up a better meter to the Fireplug battery and used the Fireplug variable resistor which gave me a pretty good solution, but I never packaged it well. Then I stopped flying for a couple of decades.
When I started flying again, I read everything I could about Nelson combat engines. Henry Nelson wrote in an article about his engines that some people complained about short life expectancy from his glow plugs. He said if you wired 4 D-cell batteries together in parallel you would never have trouble. I did this and just like in the old days with the two large round dry cells taped together, life was good.
After a few years I started flying ½-A Combat and this requires power for a starter. I decided, why not just use a Power Panel? This worked well except that I suddenly started using twice as many glow plugs as before. So, I switched back to my four taped together D batteries and added a meter to them. Life was again good except for the minor detail that this looked kind of hokey and required soldering and taping when it was time to replace the batteries.
So I built this fancy box to house to 2 D-cell battery holders from Cox International and my meter. This worked pretty well, but where the batteries had been lasting two to three years, they now lasted less than a year. Now I abandoned the nice case and glued the two battery boxes together back to back with the meter glued to them. Battery life was now down to about two months if things worked at all. I had two sets of battery leads. One set with my old DuBro battery clip that worked pretty well, and one with my fancy new clip from Cox International that would only work with brand new batteries if at all. Since I’m not willing to make things easy on myself, I further muddied the waters by purchasing some 10,000mah NiMh batteries from Amazon (10,000mah NiMh batteries from Amazon. I also needed a charger for these from Amazon.
It was now time to make all of this work as it should have been all along. I spent some time soldering the crimped connections on the battery leads and replacing another connector that broke just as I was ready to declare everything a success and now everything seems to be back to life is good. I have rechargeable batteries and dry cells for spares should the need arise. I’ll keep you posted if (when) I make more problems for myself. By the way, I didn’t mention the Sub C powered Glow Driver things because they don’t work on Nelson plugs. I’ve managed to have all kinds of problems with them also.
Gene's new battery setup and charger.
While I was building a couple of Demon vintage Combat models, when it came time to hinge the tails I decided a bit better method of inserting the hinge pin was in order. I make these pins from 1/16” steel welding rod bent to an elongated U shape. My usual method is to sharpen the ends of the pins before bending the U, then pushing them into the elevator. Most of the time this works well and sometimes I ruin the elevator in the process.
This time I cut the pins to length, marked where to bend, bent the first end, inserted to the boom, then bent the second end on the mark. I made a drill fixture using 1/8” plywood and two pieces of 1/8” thick-wall copper tubing. I glued the tubing to the plywood with C/A. I clamped the fixture to the elevator with a spring clamp. It was then easy to drill two 1/16” holes at the proper spacing and insert the pins. I almost never sand an airfoil shape in combat model elevators anymore and this time I took lazy to a new level. I merely pushed the legs of the pins into the holes and then ran a bead of C/A along the pins with a bit more where the pins were drilled into the elevator. Then wrap a 2” long piece of 1” filament tape around the pins and all done.
The elevator drill jig.
Finished Demon elevator.
These Demons were being built as models to fly various vintage engines that I have. Rather than have four engines just laying randomly on the work bench, I made a quick and dirty stand to hold them. A somewhat nicer version of this could easily be made as a display stand. All that is required is two lengths of 3/8” x ¾” wood. I used pine. And a 2” wide strip of plywood to hold them together. This could be eliminated if you wanted to drill mounting holes for the engines one side at a time. It just seemed easier to me to have the two beams held at the proper spacing. To hold the engines to the beams I used one #4 X ½” sheet metal screw in each engine. (See photo at top.)
I also used a procedure I have been using for a few years for building Combat model engine mounts that is a significant variation from what has been done on nearly every wooden Combat model since the Voodoo kit became popular in the early 1960s. Instead of gluing 3/8 x ½ hardwood to the ½ X 1¼ balsa block that is then glued between the two center ribs, I glue only the balsa block between the ribs and finish the model complete before completing the engine mount. I create a 1/8” plywood doubler and fit it to the inboard side of the wing next to the balsa block. I then glue 3/8 x ¾ hardwood beams to the doubler. These beams should be trimmed to ½” wide where they will be glued to the balsa block. I then shape that assembly and slip it onto the balsa block. I locate the engine, remove the assembly and drill the mounting holes. Now I epoxy the finished mount to the model. The final step is to fuel proof the engine mount area with slow-cure epoxy.
Demon wing before motor mount installation.
The updated Demon motor mount.
The more I build models the more I learn. Someday I may decide I know how to do this stuff.
One of two vintage Demons just off the Pape Combat assembly line.
This page was upated April 22, 2020