Playboy Senior 425 Electric (oz7883)

About this Plan

Playboy Senior 425 Electric. Radio control model. A classic old timer for 1/2A Electric Texaco and 1/2A Electric Sailplane events. The original Joe Elgin designed Playboy dates back to 1940. This modern version is 425 sq in wing area, and uses a belt drive 4:1 geared Speed 400 electric motor.

Quote: "Since the electric modeler has settled more on 400 to 450 sq. in. size models for electric Texaco, the ability to use existing SAM rule 1/2A glow-powered Texaco model kits has been essentially eliminated. To my knowledge there are no kits as yet available for these larger size Old-Timers. Tom Hunt of Modelair-Tech can make available plans for many of the popular old timer designs at the 425 square inch size. You can reach Tom at P.O. Box 1467, Lake Grove, NY 11755-0867 and ask for availability and prices. Since most of these plans must be electronically reduced on a computer graphics system, you will be required to select your own wood sizes.

For my purposes, I decided on the Joe Elgin designed Playboy Senior as my choice for a 1/2A electric Texaco model. I flew a full-size version, with an Orwick .64 ignition engine, very successfully for many years in regular SAM competitions. More recently, I built a 630 sq in version from Tom Hunt plans and with it won a first in Class-B electric Old-Timer at the 1996 E-Nats. So the choice was obvious for me.

But interestingly I learned an excellent idea while attending the 1997 E-Nats from Electric National Championship flier, Bill Jenkins of Memphis, TN. Bill showed up at the 1997 E-Nats with a 425 sq in version of the Foote Westerner. To save on building time and transporting space, Bill configured his Westerner to be able to fly in both the 1/2A electric Texaco event as well as the other provisional event, 1/2A electric sailplane. For the Texaco event you need a slow turning prop and a motor system that draws very little power, like something in the order of 4 to 5 amps. With that low current you could expect to obtain total motor run times of 7 to 9 minutes. Remember, in electric Texaco, you are looking for 15-minute total flight time.

In the 1/2A electric Sailplane event, you are back to a limited motor run (LMR) or duration class of competition. The Speed 400 size electric motor is limited to 90 seconds duration and the total flight time must be exactly 8 minutes, combined with points for achieving an accurate spot landing. So, for this event, you need high prop revs, resulting in high motor current (like 10-12 amps) so that you can obtain a high altitude in the 90 second period. As it turns out, both events require a different type Speed 400 size motor, along with different gear or belt-drive reductions and different size propellers. The model itself can be identical. The trick to this multi-event concept is being able to quickly convert from one power system to the other.

About the Playboy Sr. Over the years I've had a chance to meet and talk with Playboy designer, Joe Elgin. I even had the pleasure of watching Joe fly my own Playboy while attending his commemorative meet in Donnelsville, Ohio, back in 1992. One of the most interesting items associated with the Playboy design was Joe Elgin's choice of the wing airfoil. At a quick glance, it appears to be the NACA 6409 airfoil that was so popular with free-flight fliers of the forties and even later. Joe stated in a John Pond column (Model Builder, August 1992, page 38) that his airfoil was actually a modified Goldberg G-5. It is close to the NACA 6409, but not exactly the same.

Anyone who has flown Playboys will tell you that it seems to be the first plane in the sky to find a thermal and the last to fall out of it. Maybe that's a little exaggerated, but the fact is the glide is always slow with a low sink rate.

Construction. As with any Old-Timer design, there are always a lot of sticks and pieces to contend with. You can't buy an ARF Old-Timer for sure. I like to make up my own 'kit' by first cutting out all the wing/stab ribs and other parts using my own paper templates and then selecting and identifying all the stick wood material. There are several critical areas where the best choice of stick material is spruce rather than balsa. For example, the 3/32 sq material for the fuselage sides and crosspieces are made from spruce. Spruce spars are very important for the integrity of the wing structure. I also chose 3/32 sq spruce for the wing turbulator spars on the top, forward section of the wing. Balsa, for this application, would crack easily when handling and transporting..."

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