2015 Nats and the B Nos Dixielander

A couple of weeks have now passed since the 2015 Free Flight Nats, where I again had a great time. I flew three RC events over four days then spent Wednesday at Free Flight with Larry, Bob and Jimmy. My E-36 endeavors did not go as hoped, but I learned a lot and enjoyed it immensely.
Perhaps the biggest lesson was the importance of reliable surfaces and trim. Just a week earlier my E-202 Pearl had been in perfect trim and flying great. Then on Sunday the power pattern was way off, I spent some time chasing it before realising the fin had taken a warp due to the way I had the model stored at my campsite. I got it dialed again only to have to chase the trim again during test flights on Wednesday morning. Thinking it was OK I launched my first official flight only to see the climb again go flat and I recorded 93 seconds, well short of a max. The rest of the day was spent watching Larry and Bob fly their Lindys in B Nos Gas. It was painful to watch Bob's model glide into rising ground and miss a flyoff max by one second, but Larry was able to get the win on the day. Jimmy took second in 1/2A Classic Gas.

Next year I plan to compete in additional events, and my build list has been refined with an aim to having models for at least Monday through Wednesday next year. The A Pearl is now complete except for some small details, so on to the B Dixie. This week I added some DT hard points to the stab, made the fin, ordered a few missing hardware items, built and mounted the firewall and cut the remainder of the wing ribs. In the coming week I'll start assembling the wing and add the firewall cheeks and skid.

P-30

So slight change of plan, I was all fired up to jump into the B Dixie build but then realized I don't need it yet. Yet is relative, because I would still like to have it for the NATS in July. To back up a little, my plan is to compete over three days; Wednesday through Friday and enter three events each of those days. B Nos Gas is on Wednesday along with 1/2A Classic Gas and E-36, for both which classes I have completed models. I also have two models completed for Thursday's events, but none for Friday. So my efforts would be best directed towards getting two models finished for two of Friday's three chosen events, then adding a third to each day as time permits. It's a lofty goal, but ensures I will have a fair chance of competing in two classes per day. Considering that in some classes I may be a spectator after three official flights, having more than one model will extend my flying somewhat.

The three events I've chosen for Friday are P-30, Early 1/2A Nos Gas and 1/4A Nos Gas. P-30 is a rubber-powered event and I have a Perky 30 from StarLink FliteTech. I've had a Polecat Mk.X short kit here for several years (sound familiar?) but in the interest of expediency chose to buy an ARF model from SLFT. The Polecat is a proven winner in the hands of designer Don Deloach and others, and I am quite capable of building it but time is of the essence. The Perky will do fine for my first time out and I can have it flight ready in a matter of days rather than the weeks or months it would likely take me to complete the Polecat. Here's the model assembled as received:

Bob White's Mini TwinFin is the basis of the Perky 30, it being a European-built ARF version. The construction is excellent, everything light and clean and the covering is also top notch. With very little work it can be made flyable though is lacking a dethermalizer (DT) system, essential for any serious flying. It appears to be set up for a fuse-based popup stab, but I will fix the stab and use a popoff wing system. Two reasons for this, the Perky has fins on the stab tips and having the stab more permanently mounted will hopefully greatly reduce any trim variations related to a less than perfect popup stab mechanism. The other reason is that in a strong thermal the stab alone may not be enough to DT the model. The popoff wing will completely detach and trail the model during the descent, one wing tip being connected to the rear of the fuselage by a Dacron line. I'll use a viscous timer and copy the hold-down method from the Polecat.

B Nos Dixielander

Next on the build list is a Dixielander for B Nos Gas. This is another model that I started some years ago, the stabilizer and fuselage are framed. Now that the OS 29 is back in hand the front end of the fuse can be completed. I was fairly certain I had cut a full set of ribs for this model but discovered this was not the case, the ribs I remember having are for a smaller A Gas version. Fortunately I had previously decided on spar sizes and cut a ply rib template, so slicing some ribs will not be too large a task. Here are the first 8 cut from 3/32" balsa, I think another 19 are needed.

For the uninitiated (which includes the writer), B Nos Gas refers to the size and class of model. "B" being engine sizes in the range of .20 to .30 cubic inches. "Nos" refers to Nostalgia, which if I understand correctly includes all models for which plans or kits were available during the years 1943 through 1956. Some models kitted after '56 are also approved. "Gas" refers to the fuel source, originally being gasoline. The engines I have run on alcohol (methanol) which is not typically referred to as "gas" other than in this case. Gasoline-burning engines are still used in some classes but they are the minority. Here's another shot of the OS .29, showing the new cylinder head and next to it the original finned head. Engine run times are so short that no cooling fins are needed.

A shot of Dixielander designer George Fuller with a stock Dixie of 50-inch span.

Engines back from rework.

Occasionally I get a card in the letterbox saying that I have a package to be collected at the Post Office. Normally I find this quite annoying, as I do enjoy getting parcels, and having to wait an extra day for them is no fun. This Monday such a card appeared and I had a reasonable idea that it was a couple of free-flight engines back from the attention of Bob Mattes. And so it was, slicing open the box revealed an nicely oily Cox TD .020 and OS .29 III.

The Tee Dee is destined for a 67.5% Dixielander for 1/4A Nos Gas. I had long been searching for an .020 is reasonable condition but the prices were more than I was willing to pay. Eventually I was able to find one online for a moderate amount, and shipped it to Bob to have him apply his magic. He does some internal work, and machines a new head to accommodate a GloBee-style drop-in plug. I'll be using Merlin-branded equivalents of these flat-coil plugs. Bob provides complete details of the rework and test running, by the time he got done with it the TD was turning an APC 4.2x2 prop at a little over 25K rpm on 65% fuel.

The OS came from the generous heart and home of Larry Davidson, though to be fair he did steal it out from under me at a swap shop. Hardly my fault that his experienced eye and treacherous nature snagged it before I could figure out what I was looking at. Nevertheless, it's mine now and will find a good home in a B Nos Dixielander. Perhaps one day the scales of justice shall tip a little in my direction and I will use it to beat the socks off him. Bob machined a Nelson-style head for it in addition to some internal cleanup. In the interest of longevity this is a relatively mild build, after rework it spins an APC 9x4 at 16,800 rpm and will probably be nearer 18K once fully broken in.

Keil Kraft Senator

In early 2010 I discovered online the Keil Kraft Senator, and eagerly read through the various threads on building and flying. Not being able to find the plans online, Jim Moseley was kind enough to send me a copy from Canada at his own expense. That was almost precisely five years ago. I'm not exactly sure what happened but little to no progress was made for several years. I had the plans out periodically but for various reasons never made a lot of progress.

Forward to late 2014 and a renewed plunge into Free Flight building with a goal to competing at the NATS in July of 2015. While not intended for that event in particular, I decided it was past time for the Senator to get built. I set all other projects aside and focused on accomplishing something each day, no matter how small. Ribs were cut, propeller blank assembled, and hardware gathered. Before too long the fuselage, wing, and tail sub assemblies came together and were prepared for covering with Esaki tissue. Thinned white glue (yellow actually) was used to adhere the tissue to the structure, which for the most part went well. The exception was the lower surface of the wing, being undercambered the tissue needs to be stuck to the length of each rib. This was a little frustrating until I got the hang of it and the last couple of panels were less of a struggle.

I'll post more build images in the future but the Senator is done and ready for test flights when time and weather permit. I'm looking forward to seeing it in the air.

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.