Viper II (oz6326)

 

Viper II (oz6326) by Carl China 1966 - plan thumbnail

About this Plan

Viper UC Team. CL Proto B Speed model. C China, MAN Sept 1966.

Quote: "After five years of active flying in the Class H Proto Speed event and somewhat less time in the other speed classes, it is my belief that Proto Speed is the most sophisticated speed event of the group. To the non-speed flyer, the generous wing area, airplane size, and convenient fixed landing gear belie the true challenge of flying proto speed. The combination of good airplane design, engine capability, and pilot flying ability is essential in proto.

Viper II is a derivative of earlier Viper I protos. On initial tests, under winter flying conditions, Viper II attained speeds just under those which placed in Open Proto at the 1965 Nats. Speeds of 128.5 mph were realized using a stock rear venturi Super Tigre 29 with strictly commercial fuels. Based on this preliminary success, the Viper concept of a thin airfoil, low aspect ratio wing proto design, and Super Tigre engine appears to be a winning combination for seasons to come.

My original interest in speed was generated prior to my military service at a 1951 Jacksonville, Florida, contest. By 1957 I had flown proto in several contests at Waco, Texas, but I was basically a sport flyer until 1961.

At this time I began the design of Viper I for the USAF World Wide Contest. The original two-line model placed sixth that year at 101 mph. In succeeding years improved versions of Viper I placed consistently in open competition, including a third, second, and a first at the USAF World Wides of 1962, 1963, and 1964 respectively. In 1964 I had changed to Mono-Line and was then achieving proto speeds of 118 mph.

In late summer 1965 I decided to update the design and build it for the new rear venturi Super Tigre 29 (ST 29 RV). The major changes I planned were a reduction of the 6% wing thickness/chord ratio and a lighter structure. With these objectives in mind, I started work on the second generation proto design, Viper II.

Performance: Viper II was completed in the fall of 1965, just in time for a few test flights before the Ohio winter set in. In order to obtain a good initial evaluation of both the airplane and the ST 29 RV engine, it was decided to run only one size prop, a Top flite 8/8 Speed Prop cut down to 7-1/2 inch diameter; two commercially available fuels, K & B Speed Fuel and Speed 55; and the Fireball cool, long reach plug. Thirty-one flights were flown, 19 with two of the new ST 29 RV engines and the remainder with a home-built hybrid engine which, incidentally, was slower than the Super Tigres. All flights were flown in 55° to 65° temperatures and the performance with the ST 29 RV was as follows: The first flight was 124 mph and speeds quickly progressed to 128.5 mph. The slowest speed was 120 mph on a lean setting. The average proto speed of all flights for each ST 29 RV was over 125 mph. These performances were with Mono-Line. For builders who prefer two-line control, this type control system is also shown on the plans.

Although it is not yet known how other brand engines will compare in this design. the Super Tigre has been very impressive. Both of the ST 29 RV engines tested were stock except that I substituted a Dooling needle valve system with a McCoy right angle jet. However, this is simply a matter of personal preference.

Experimentation to find the best prop-fuel-glow plug combination for the weather conditions of your particular area should yield higher speeds.

The cowl is designed to accommodate both the front and rear venturi Super Tieres. For builders who plan to use only the rear venturi engine..."

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Supplementary file notes

Article, thanks to theshadow.

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Viper II (oz6326) by Carl China 1966 - model pic

Datafile:
  • (oz6326)
    Viper II
    by Carl China
    from Model Airplane News
    September 1966 
    24in span
    IC C/L
    clean :)
    all formers complete :)
    got article :)
  • Submitted: 02/02/2015
    Filesize: 316KB
    Format: • PDFbitmap
    Credit*: dfritzke
    Downloads: 1110

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