Author: Don Grissom
Edition: Model Aviation - 2011/11
Page Numbers: 121,122
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Radio Control Combat-2011/11

Don Grissom [[email protected]]

Quick and easy bladder tank

Earlier this year I decided to change my airplane back to a design I had used once before that flew well. The Falcon, designed by Lee Liddle, is a flying wing with the engine mounted on cutting-board material on the front. In past designs I had always used a bladder system that would push the fuel to the engine instead of using the back pressure off the muffler.

After attending the Nats, I talked to Sam Windsor and he showed me a bubbleless tank. I had seen some people use them for scale designs but never thought about using them for my Open or SSC airplanes.

The design is simple to build with a few supplies you can obtain from a hobby shop and a grocery store. Round tanks seem to work best because the bladder is also round.

Materials

  • 6-ounce Sullivan round tank (Sullivan tanks are nice because the bubble is at the top)
  • Du-Bro #241 pressure fitting
  • Playtex 8-ounce standard disposable baby bottle liners
  • Copper tubing and a small piece of fuel tubing
  • Screw and glue (for sealing)
  • Syringe (for fueling and removing air)

Construction

  1. Drill a hole in the bubble at the top of the tank to accept the pressure fitting, then screw the fitting in place and use glue to seal and prevent leaking.
  2. Push a bottle liner into the tank, leaving some of the liner protruding outside the tank.
  3. Since you only need one line going into the tank, put only one tube into the stopper; close the extra hole with a screw and glue.
  4. Place a small piece of fuel tubing on the end of the copper tube so it will not damage the liner.

Mounting and use

  • Mount the tank in the airplane with the bubble on the bottom so any fuel that goes through the pressure connection can be drained.
  • Use a syringe to fuel the tank; this lets you remove all air from the bladder before putting fuel in the tank. With no air in the tank and only one way for the fuel to go in, you won’t get air in the line and you will use all of the fuel in the tank (unlike using a clunk).
  • After testing, this setup worked well on my airplanes. Another advantage is that you can put the tank sideways and it will still work.

RC Combat Nationals — Muncie, Indiana

Every summer we have one of the biggest events of the year at the National Flying Site in Muncie, Indiana. The RC Combat Nationals are a four-day event with 40 rounds of combat. I have been going to the event for many years, and although this one had fewer people attend, it was not without good flying.

I had planned a new fleet of airplanes this year, but looking back I realized I should have done a little more preparation. Normally one of the top pilots at the event has been Brian Gilkey—he has won most of the Nationals in the past five years. This year he was not able to make it, so he left it up to his younger brother Eric to keep the winning tradition alive.

Early rounds: SSC and Open B

We started the week with two days of both Slow Survivable Combat (SSC) and Open B—five rounds of each per day. The biggest contest of the week was SSC with 13 pilots. William Drumm III got off to a fast start with some high scores; Andy Runte and Bill Geipel also started well.

I was not that lucky—right away I had some engine problems I had not experienced before. I had flown this design earlier in the year at another contest with few problems, but this was not going to be my day. I ended up pulling out of Open B to try to resolve my engine issues.

After the first events were done, we ended up with a new pilot on top this year: William Drumm III. He flies his own design that turns fast, and he is also a very good pilot. One thing I noticed is that he does not seem to get into trouble by staying in the furball too long.

Scale and Limited B

After completing the official classes, the last two days were for Scale 2948 and Limited B. After so many issues earlier, it was nice to get to fly—my Scale models had few problems.

I was flying the Ki-43 Oscar sold by Chris Handegard. It’s a good kit I have flown for many years. One advantage Eric Gilkey had in Scale was that William Drumm did not fly Scale—at least not at that time—so Eric had a chance at first place.

Because we did not have many hard midairs, we were able to fly all 10 rounds in one day. This is not normal; Scale can cause some of the worst damage. After the 10 rounds, Eric Gilkey finished first, Nicholas Windsor (from Florida) came in second, and Rick Wise placed third.

The final event of the week was Limited B. Over the years this has become a great event: slower than Open B but fast enough that you don’t have as many issues with wind and getting airplanes airborne. We started the day with one of only two pilot-line infractions for the week. The weather had been nice, but the wind picked up slightly that day. After flying five rounds Friday, we completed the remaining rounds Saturday and then packed for the drive home.

If you are going to travel to a contest next year, this is a great one to attend.

MA

Sources

Transcribed from original scans by AI. Minor OCR errors may remain.