The flying monkeys got me...

Helis and fixed wing

AMA 957918
IRCHA 4345
AMA Intro Pilot Instructor

Saturday, June 7, 2014

I got gas...

Well, its happened. And its about time it did! Why didn't I do this sooner?

I bought a 30cc gasoline powered Goldwing Sbach from Kenny Chandler last week on a deal we made. I made some mods, adding a Quikfire filter/primer, changes to the throttle linkage, tightened the rudder wires, fixed the receiver charge plug alignment, and set the plane up on my DX8. I had never setup dual elevator servos, but it was a cinch.  The cowl is good, but thin, and may need replacing soon. The most, and still problematic issue, is the gas can: the top is designed to be punched out so there is a pre-cut line all the way around the cap. This already tried to separate. I used JB Weld as it is gas resistant, and it provided a great seal. But yesterday I noticed it was already coming loose intact on the top...

Setting up the DX8 required I setup and tune the engine trying to find my idle and servo limits. For my first time I did alright. I still get a little four-cycle action at full throttle but just at first (I believe this means she is still a little rich at full throttle).  Flying electric I am used to a lot finer resolution: this throttle has idle, medium fast and full throttle, more or less.  Its a DLE 30cc with a Pitts muffler (bought a silencer for her not knowing someone had upgraded her to a Pitts...), turning a 19x8 Xoar laminated prop. She gives me a reliable 6700 rpm with an idle around 1670. This produces nice full power thrust and at idle no thrust. The manual says a generic (i.e. no prop noted) max of 8500 rpm, and some with less prop are getting pretty close to that, and idle at 1700. Kenny says the 6700 rpm is plenty, so we'll see. I think she will still need some fine tuning. My fear is the engine quitting at idle... this is my only beef with gas, and I think its only a problem during setup, is losing the engine in flight for an immediate dead stick landing.

Here are her specs from my log:

Goldwing Sbach 30cc Gas

  • Battery: Rcvr 6V NiMh 2700,  Ign 4.8V NiMh 2000
  • Engine: DLE 30 with Pitts, NGK CM6 at 0.02 gap
  • Prop: 19x8 Xoar or Bambula
  • Optical Ignition Lock
  • Servos: 
    • Throttle: Hitec 5985
    • Elevator (x2): Hitec 5645MG
    • Rudder: Hitec 7955TG
    • Aileron (x2): Hitec 5645MG
  • Receiver: Spektrum AR7210 with Satellite
  • Comments: My first gas plane!  72” wingspan.  Miracle Ign/Rcvr Switch, Quickfire


The JL Products Quikfire installed (the blue aluminum thingy). This acts as a filling/fuel delivery hub, gas filter and primer. It holds about 1/4 oz of gas once primed so that after the first start of the day all of the following starts should be quick.

It requires one port to the fuel tank and the vent/siphon preventer, and that's it. Had to MacGyver a cap for the extra tube. Otherwise nothing different. I did modify the firewall routing of the Tygon tubing, but that was it.

No sharp angles.

Top line going into the QUikfire is from the fueling button, the bottom one to/from the tank. 

Those weights are gone. Kenny noted the plane was already nose heavy and in my prelim CG tests that was the case. I took off about 3 oz of added weights, the Quikfire adding back a smidge. She seems well balanced now, certainly not tail heavy.

The plan is to take her out to the field today. Its not really a maiden as she has been flown before, but it will be my first gas flight. I am so used to the reliability of electric, and I have see so many people farting around trying to get their engines to run (and my tuning was not without its moments), that I don't yet trust. I hope to get her running as smooth I have seen others achieve.

Not to be forgotten, I will also be taking the 70 sized electric Sbach #2 out for her maiden today! More to follow.

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