Cermark signature series: Ptiis S-2B

Model Airplane News, Dec 2000 by Uravitch, Rich

IMAA-legal, almost-ready-to-fly aerobat

The basic Pitts design has been around far years; the construction materials have changed and the horsepower numbers keep rising, but the longevity of the airframe proves that it works, and the revered Pitts has gained a place in the hearts and minds of aerobatics enthusiasts. No surprise, then, that the airplane has found its way into a variety of kits, starting many moons ago with the Berkeley and Scientific control-fine models up to one of the newest offerings, the Cermark* Signature Series S-2B Pitts ARF.

Designed by noted pattern flier Dave Patrick, this model follows the lead of the full-scale version and subscribes to the "minimum weight/maximum horsepower" school of acrobatic airframe design. The fuselage structure is mostly lite-ply with some birch ply and balsa added where necessary. Extensive lightening techniques are employed in the manufacturing process, most evident in the fuselage sides where large open hays separate the former (bulkhead) locations. Surprisingly, you can actually look quite clearly through the entire length of the fuselage from firewall to stabilizer. There is no structure except for that deemed necessary to absorb flight, power and maneuvering loads. Does that mean this Pitts is delicate and flimsy? No; but it does mean that you shouldn't routinely drop it in from 70 feet on landing as you do your sport model! The Cermark Pitts is clearly as rugged as it needs to be to deliver the performance of which it's capable.

IN THE BOX

I must admit that I was impressed on opening the two boxes that the Pitts comes in. This 60-inch-span (IMAA-legal) Pitts is a good-size model, and the typical Pitts red with white-and-black-trim scheme is executed in a manner that most of us model builders couldn't match. To protect that neat Ultracote finish, all of the components are packaged in clear plastic sleeves. The fiberglass cowl and wheel pants, cabane system and interplane struts are prepainted and come fairly close to matching the Ultracote. Reds are difficult to match perfectly, as I found out later when painting the aluminum landing gear, but the match on my kit was fairly good. The wings are completely built at the factory, so you need only hinge the ailerons and install the interplane struts.

You'll be guided through the assembly sequence by a photo-illustrated manual that is, at best, adequate. Although you can use it to assemble the model, the manual could have been much more helpful and informative. For example, it takes nearly three pages (with photos) to tell you how to install an aileron servo, but the installation of the interplane strut connectors is covered by only one captioned photo. The I-strut connectors are metal fittings that you screw into predrilled and tapped holes in the upper and lower wings. Two of the holes on my kit were stripped, so I suggest that you "harden" all of them with thin Zap* to beef up the threads. In addition, the holes were too tight to allow the strut-attaching screw to pass through; check them and drill them out if necessary; it's much easier now than after they're installed in the wings. Install the top wing, make all the necessary adjustments to the strut connectors and strutsmaking certain you don't introduce a twist in the wings or change the incidence toward the tip-then secure the metal I-strut connectors with a drop of thin Zap on their threads. Mark the struts "L" and "R" so if you ever have to take the Pitts completely apart, all of the settings will remain as they were.

Assembly progresses fairly quickly, as the kit includes nearly all the hardware required. You'll need only some Zap or epoxy to anchor the horizontal stabilizer and vertical fin and some more Zap for the hinges.

The kit comes with a beautiful aluminum spinner and backplate and numbered bags that contain all the hardware called out in the assembly steps. You won't have to buy much to complete your Pitts; 3-inch wheels, a 16-ounce fuel tank, strips of hook-and-loop fastener and all necessary pull/pull cable controllinkage parts are included.

Five servos are required for the Pitts; one for each aileron and one each for throttle, rudder and elevator. I used a JR* 6-channel XP642 radio with JR's low-profile, hightorque servos on the ailerons. Although the Pitts is not a huge model, it has fairly large flight-control surfaces that demand fairly torquey, high-resolution servos for precise control to deliver the style of aerobatics necessary. Don't skimp here; the model deserves it.

When it comes time to select a powerplant for the Pitts, a .90 to 1.20 2- or 4-stroke will fly the model. The instructions illustrate the installation of a YS .90 and 1.40 as well as a Zenoah G-23 for gas-burner fans. I decided on a Magnum* XL-1201tFS.

FINAL THOUGHTS

Because no glassing, filling, or covering is required, you may spend 12 to 15 hours assembling your Pitts. You'll be impressed with the result, and so will the rest of the fliers at the field. And you know what? You probably couldn't build, finish and equip a similar kit-built model for what this ARF costs.