RO8 (oz5850)

About this Plan

RO8. Two meter sailplane.

Quote: "The RO8 may not be the Utopia of the 2 meter class, but so far it has yet to finish out of the money.

Having long cooked my simple brain by over exposure to the sun while flying sailplanes, I have found it necessary to number each of my designs. You will note that the sailplane presented here is Number 8. To assist in remembering who I am (should someone ask) the number has been preceded by my initials. By placing the above information on my sailplane, and given a little luck, I am usually able to locate the thing in time to launch with my flight group.

The RO8 follows a general design concept started 18 months ago with the RO4, my first two meter design. The PO4 was intended to be light, durable, fast, and easy to fly. With a 5.2 ounce per foot wing loading, it was light. It was durable. It had a 8% thick flat bottom airfoil section and was only fair in the speed department. Even though I managed to place in both contests entered with the RO4, it was not what I wanted and it was not particularly easy or fun to fly. Basically, it was not the utopia we all seek and never find.

Before returning back to the drawing board, I felt that it was necessary to re-examine the design objectives and establish some very basic priorities having to do with why adults are willing to endure extreme hardships for the sake of flying a sailplane. The answer seemed simple! We fly because it is fun - or should be. So priority one demanded a design that was easy to fly and, therefore, fun to fly.

Priority two tended toward satisfying the desire to create something a little different, a little sexy if you will - a design that might inspire the question: I give up, what is that?

By nature I tend to be fiercely competitive and so priority three demanded a design which could win any given two meter contest regardless of the tasks involved.

Priority four involved durability and ease of construction. I love to fly and hate to build. Repairing broken sailplanes causes my entire family to suffer unusual punishment, so the design had to be simple to build and very durable.

Toward these various goals the following criteria was set forth:

(1) Light wing loading forflying light lift with the limited efficiency available in a small wing.
(2) Semi-symmetrical airfoil section for penetration at a light loading and for speed when loaded up.
(3) A thick 12% airfoil section to provide a wing volume sufficient to make the bird easy and responsive to fly. It also allows for a decent main spar height.
(4) A low mean camber value of 2% to keep the center of lift from wandering all over the place which again makes the RO8 easy to fly. A side benefit is the acrobatic performance it generates.
(5) A tiny fuselage cross section to reduce parasitic drag.
(6) Symmetrical airfoil sections on the fin and stabilator to reduce drag and make control inputs smooth and progressive.
(7) A T-tail configuration to assure the solid effectiveness of the stab and, perhaps, for less drag. A secondary consideration was that of removing the stab from the danger of being wiped out by my head when hand launching.
(8) And lastly, an airframe which is efficient ie high strength to weight ratio, and which is fairly straightforward to build while still maintaining enough durability to withstand the rigors of competition.

With these objectives fresh in my mind, a blank piece of paper was taped to the drawing board and the RO8 started coming to life. Things such as surface areas, tail volume, moments, etc were calculated and the design was roughed out on paper. Then came the true stroke of luck. My neighbor walked in to investigate what strange thing I was up to this time. I looked down and there it was. a perfect 12% thick, 2% mean camber, size 11 brown Florsheim shoe. I quickly traced the airfoil as my neighbor stood somewhat precariously upon the drafting table. This once again proves that sailplane design is in fact an exact science.

The truth is that the R08 looked so promising that construction was started without ever finalizing the plans. Two weeks later the R08 was given a slight push into the wind.

And that's when the love affair started. That sailplane was connected to my right thumb I mean directly connected. Think turn and it turned right now, think penetration and it moved right out without the sink rate going completely away, think minimum sink and you would easily believe that the wing contained a lot of helium..."

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