Waterman Arrowbile (oz14392)

About this Plan

Waterman Arrowbile. Radio control scale model. Pusher-prop, flying wing layout.

Quote: "A sport scale model, add or delete scale details as you like. A gentle and stable model that will stop the action at any field. The Waterman Arrowbile, by Earl Witte.

With the advent of the new lighter and more reliable equipment, it was bound to happen. This happening is Sport Scale, and why not? Now the radio doesn't restrict the airplane's design like it did in the past. Let's face it, we all like to fly planes that look like their big brothers. Check the Goodyear racers, since they are good examples of sport scale designs that look and move like their bigger twins.

Maybe you are already an expert builder and flyer, maybe not. Either way you have a great choice in this hobby. Perhaps you have been reading Dave Platt’s inspiring scale articles and you're hot to go scale. Good. You might try one of the more tried and true models or maybe something different.

In my case, my bag is always 'something different.' It seems like I can never build the same model twice. I am always scrounging around for details of unusual designs, either vintage or modern.

A while back when I was at the library - I mean hobby shop - I picked up one of the Historical Aviation Albums. You can really find some gems in these magazines. The first time I read through this book, nothing really caught my eye. However, after reading the article about Waldo Waterman's Arrowbile for about the sixth time, I had it! Something about this plane really grabbed me. The more I looked at it, the more I thought - it can't fly but it does fly and well, too. This Waldo Waterman had to be a genius. Just study the design carefully and you'll see he really built an engineering masterpiece.

Take the rudders for example. Look simple, don't they — they are. But only one works at a time. For example, when turning left, only the left rudder moves outward. This efficiently works as a combination of drag and deflection. My model actually turned better on rudder than aileron before I coupled them together (via wiring harness). How about the combination of constant chord, sweep and 4° washout to give the wing safe and stall free flying characteristics? There are many more goodies built into this design, not even mentioning that it makes into a lousy racing car.

Complete information on this plane can be found in Historical Aviation Album, Volume III, available from Paul Matt, P.O. Box 33, Temple City, California 91780. I would like to take this opportunity to thank Mr Matt for helping me to obtain the approximate CG from Mr Waterman. More about this CG problem later. Did you notice the beautiful photos? That's what I call close-ups. These photos were taken by our club lens genius, Bill Crame. Bill is one of the unsung heroes of our club, the Signal Chasers of St Louis. Bill takes thousands of club publicity photos for gratis only.

Back to the Arrowbile. This plane makes for an excellent model subject. It could be built by the very serious scale modeler as 100% scale. With all of the small details - radiator, handles, grilling, etc a real scale builder could go the limit. My version is more the sport scale type, although I tried to make the plane as close to scale as practicable. The main outlines of length, span, and height are scale. The main gear tread is widened from scale, and I had to add some non-scale engine cooling scoops. Being an experimental model, I also chose painted-on windows and pantless wheels for strength and simplicity. If you decide to build the Arrowbile, you can add or delete details as you prefer. The version I built was NR 18932 featured on the Historical Album plans. I finished it in scale red and white, and it is a beautiful ship. The Historical Album can be used for a scale presentation, however, there are no actual color photos of the plane.

To me, flying wings were always the great mystery posing many unanswered questions. How can they be stable without a tail? How do the controls react? What type of controls are used? Will it tip stall? How does it glide without power? How about take-off and landings?

Maybe you had the same thoughts yourself about flying wings. Reading about the Arrowbile's gentle and stable flying characteristics was not enough, I had to build it and find out myself.

I wish I could say that it flew off the board but it didn't. The first trip to the field was uneventful. All we accomplished was to put about 8 miles of taxiing on the speedometer. We did manage to flip it upside down testing the durability I claimed it had! Unscathed, but unflown, I trudged back home.

My test pilot, Crash Litzau, and I talked this non flying problem over. The violent ground oscillations we had on the first attempts were thought to be caused by tail heaviness. As a consequence I added many ounces of nose weight.

The second attempt was similar to the first, except with all that lead even the nose didn't bounce. Obviously, this was a step in the wrong direction. Needless to say, these unsuccessful attempts were discouraging. Even Crash looked a little shaken.

Back home again, and I knew I had a basic problem with the CG. I decided on a most drastic measure - what I call the 'Einstein mind link.' I accomplished this by carefully consuming 3 to 4 containers of foaming beverage while listening to Country Western. Flash - it happened. The answer was clear. It was nose heavy, but how much? I referred back to Paul Matt's letter from Waldo Waterman. He stated the CG was around the fuel tanks on his full-sized plane. My model balanced about 1/2 in in front of this point. I added tail weight to move the CG back about 3/4 in, and cooling scoops to the engine compartment. Engine overheating was also a problem.

Now full of confidence, I called Charlie for a flying date. After telling him about my latest modification, he regained some of his initial enthusiasm.

The third attempt was now at hand. The engine was all fired up. Charlie signaled OK, and let it go. At first it waddled slowly, but soon it was rolling faster and faster. Charlie hits full up - look, it's breaking ground. Up and up it climbs. It's no longer the ugly duckling on the ground. Now it's at home in the air like a soaring eagle. Shortly after, the engine quit and jolted me back into reality. The glide is beautiful - twice as far as one would expect. Safely down in the grass, I let out an Indian moose call that they still talk about in Canada. With the pressure off, we got in two more flights that day. Later in the article I will discuss flying the Arrowbile in more detail. However, I will say again - it does fly, and well, too. It's a real challenge for you avid RC enthusiasts.

I am going to deviate from the usual step by step construction sequence. Instead, I will just hit the main points of the craft.

Fuselage: The fuselage on this type of ship has to be very strong and robust. You will notice plenty of plywood and balsa blocks. This makes the fuselage almost indestructible. There is room for equipment installation, also your lunch, TX, and tools!

The receiver and battery pack locations should be left to last. Try to use them to balance the ship instead of using lead weight. Needless to say the CG location should be exactly as shown on the plans.

My ship weighed over 12 lbs. Some of the overweight was my fault; I built some weight into the leading edge of the wing that I did not need. The landing gear incidence is very important. Double check this against the plans. Too much of a nose high attitude will cause porpoising..."

Direct submission to Outerzone.

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