Runaround (oz14254)

About this Plan

Runaround. Radio control sport pattern model.

Quote: "The Runaround, by Dick Hanson. This month, Dick switches from 'How to Fly Pattern' to 'What to Fly Pattern With'. Designer of the popular Tiporare, had the Turnaround in mind for this one.

If you are a Novice or an Expert, this design is for you! Sound familiar? Maybe so, but let me tell you about the rather Plain Jane looking design we call the 'Runaround'.

Approximately seven years ago we worked up the Tiporare (oz12175) design, which has been well received by many pattern buffs. Then two years ago we worked up a very scale-like Dalotel which has also been extremely successful. These two designs spent so much time together the result was inevitable. You guessed it. The Runaround is a direct descendant of these two designs. Like most offspring, it looks more like one parent than the other. In this case the planform is much like the Dalotel, but the chin is from the Tipo as is the basic size.

The airfoil that evolved is a slick 12% section that really works! This is the thinnest section we feel practical for most fliers. The wing loading must of course be kept down when using this section at low airspeeds. No problem here, because the Runaround's 750 sq inches carry only 6-7 lbs. of weight. The powerplant recommended is a .90 four-cycle that will easily turn 10,000 to 12,000 rpm. We like the OS, but the new Enya .60 may be a good choice. The new electrics should also be considered.

If you have flown or watched large TOC models being flown, you will note that the best ones are not too fast, but have excellent vertical performance plus airspeed stability. Air brakes, variable speed props, thick airfoils, etc, are not required to achieve these characteristics. High power and a relatively large propeller seem to be the best setup for these big models. This can be duplicated in a smaller size model.

Here's how. The OS .90 turns 10,000+ on 12 x 10 propellers. It only weighs 24 oz, which is less than a .60 using a tuned pipe, and it has the advantage of being the easiest starting engine I've ever tried. I'm talking one-flip starts in below freezing weather. Add very low vibration and only 7 ozs. of fuel required for a FAI pattern. You can see why I am so taken with this engine. it's reliable, light, and fuel stingy.

The shape of the Runaround was not based on looks as much as function. The inverted engine, which we formerly resisted, is very acceptable when using a four-stroke, because flooding is not a problem and tank installation becomes very easy - mainly because it doesn't have to clear an exhaust system. The deep chin, as used on the Tipos, is very desirable in our opinion, both for lateral area distribution and general streamlining. It is extended even further on this design.

Studies of the airflow over the top of a fuselage indicate a very smooth line is desirable from the spinner to the vertical fin. The setup shown is quite slippery, and in fact, allowed the use of a very short vertical fin. Abrupt canopy lines do cause more turbulence, which can cause tail wiggle if the vertical fin placement is not correct. We have tested this phenomenon extensively. The scale Dalotel has an abrupt canopy entry and requires the tail rudder/fin setup to prevent wiggle. If you want to experiment, make a foam block about 3 x 3 inches and tape it to the top of your model's fuselage at various points. You should encounter rudder blanking at some point, which will induce a steady wiggle in the model.

The high stab placement is deliberate, and we feel it is the most desirable placement - if the idea is to keep it away from wing wake. The adjustable engine mount allows us to dial in neutral pitch arrangements by shimming at four points. We also kept the high thrust line, swept wing LE and large stab used on the Dalotel. The low speed stability of this arrangement is very good. It will fly at approximately 20-25 mph.

The fixed swept gear was swiped from light plane practice. Its effective in reducing bounce and best of all, it's L-I-G-H-T. Having no gear in the wing allows a finished wing weight of 24 oz. That's including finish, servos, and all!

If you are still interested, we will describe the basic construction concept used. It's really not for beginners or nervous types. The version shown is intended for good builders, who live to cut lots of balsa parts..."

Direct submission to Outerzone.

Wingspan: 65 in
Weight: 6-7 lbs
Engine: 0.90cc RC
Type: RC 4 channels
Drawings and Prototype built by: Dick Hanson
Published: Model Builder June, 1985

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