1/2A Country Boy completion

The National Free Flight Society (NFFS) and Bill Vanderbeek sponsor a One-Design event at the NATS each year. In 2010 the chosen model was the Jim Clem-designed Country Boy, in 1/2A size. With the intent of competing, I built one from a BMJR Models kit and finished it to the point of needing only a few small items to be flight ready. Ultimately I did not compete in FF that year (nor yet, for those keeping track) and the model languished until I dragged it out of storage last week. Having survived several house moves without more than a few dents and scrapes I set about finishing it and will have a go in 1/2A Classic Gas at this year's NATS.

For no particular reason I did a Google image search for 'Jim Clem Country Boy', and the second row of results contained the below image of my daughter Amelia with the framed model. I was pretty shocked, and pleasantly surprised. She would have been around 5 years old here, she's now 10 going on 11.

The first thing I did was finish the dethermaliser (DT) system. This uses a viscous timer with a 'rat trap' force multiplier to retain the stabiliser. I had not installed a tension spring to drive the timer so wound one from .010" music wire and after testing the run time to determine the location and tension, screwed it in place. I also had not installed a stop for the DT line, this was made from a piece of aluminium tube and attached to the fuselage side in the appropriate place to give 45 degrees of stabilizer deflection. A small piece of silicone fuel tubing serves as a shock absorber. In this image that tubing is not yet in place but it can be seen in the last photo. The larger spring is .020" music wire and provides tension to hold the stabiliser down.

Then on to the fuel system. I'm using a latex bladder and filling will be via a check valve in the aft end. All these components come from Texas Timers, as does the engine timer. To complete the engine side of things I am only short a spinner nut which is coming from Bob Mattes. This will center the prop on the shaft and also provide a little nose weight.

Last was to index the wing and stabilizer to the fuselage. I used small basswood blocks for this, installing them permanently after measuring to center the wing and stab on the fuselage.

I'll probably rig some kind of quick DT for the first flights but otherwise it's ready to go. When the weather warms a little I'll take it out and see how it goes.

Folkerts SK-3 Peanut

The Air Racers of the 1930s are perhaps my favorite aircraft type of all time. I'm drawn to many of the aircraft of this period, but some of the most appealing are the slim machines designed by Clayton Folkerts. While searching for free flight plans of the SK series I discovered the Peanut SK-3 designed by Kurt Enkenhus and published in the January 1978 issue of Model Builder. Unfortunately the full-sized plan had been suspended from the great resource that is Outerzone, so I looked elsewhere, but in vain. I then was able to find a copy of the magazine but the plan was not full size, nearer to 50% at 6.5" wingspan.

The article attached to the plan is remarkable. It contains Kurt's performance calculations based on weight, available power, drag and propeller efficiency. The completed model performed essentially identically to the prediction.

A work colleague (thanks Michael!) happened to know that the collection of Model Builder/Bill Northrop plans were now in the hands of the Academy of Model Aeronautics. An email to them resulted in a print being made available for a moderate number of shekels. Great service from Greg Prater at the AMA and a happy end to the day.

I doubt I will build this as a Peanut. My intention is to enlarge it somewhat, perhaps as much as 400%. I'll figure that out later. In the meantime I have the Ralph Kuenz SK-2 plan, and the SK-4 short kit coming from Volare.

A-Gas Pilfered Pearl fuselage

This week I've been glassing the Pilfered Pearl fuselage. I also decided to move the timer forward as the length of fuel line between the pinch-off mechanism and the venturi seemed excessive. I moved it forward a couple of inches and am happier with the location. Maybe it would have been ok as is but if engine run times had been inconsistent I'd wish I'd spent the time to move it. In the second image you can see the patch in the fuselage side where it was previously mounted.

I had intended to paint the fuselage but it will stay natural. Some time ago I covered the stabilizer with UltraCote film but recently had planned to strip it, then cover it and the wings with Polyspan. In the interests of saving time I decided to leave the stab as is and complete the wing with UltraCote film also. That will be enough colour, and I like the look of the natural balsa fuse.

Power is a stock K&B 3.25 (19cc), with a Texas Timers MAX IIIA timer. Only a few small things to do and it will be ready to go once the weather gets a little warmer. I'll be flying it in A Gas so might be at a disadvantage against the bunters, but I'm not available for A/B Classic so I'll take my chances. This is a learning year anyway, I'm looking forward to just participating.