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Racing the Diana
I had the good fortune to pilot the first new production Diana at the Uvalde 15 Meter Nationals and would like to offer a recount of my impressions of this aircraft and how it performed against the best pilots and sailplanes in the United States.
Mr. Jerry Zieba of Diana Sailplanes contacted me in April and kindly offered Diana 'Zulu Juliet' for me to fly in the 15M Nationals at Uvalde. This aircraft would be the second production model Diana, but the first aircraft produced by the newly formed Bogumil Beres facility. The aircraft was finally shipped from Gdansk on 4 July. Jerry picked it up in New York harbor on July 23. After a whirlwind of driving and paperwork, Jerry miraculously arrived with the Diana at Texas Soaring Association on July 29th.
With little time for preparation and practice, I arrived in Uvalde on 1 August, and conducted four practice flights prior to the competition. These flights culminated with a winning speed of just under 100 mph on the second practice day. My initial impressions of the Diana were quite positive!
As most people know, the trailer and assembly procedures are a bit unusual in that the spar stubs are fixed to the fuselage instead of to each wing. Substantial carbon fiber spar stubs protrude about 30' beyond either side of the fuselage. On assembly, the fuselage is first rolled out of the trailer on a dolly which, by means of a clever hydraulic jack, keeps the fuselage spar stubs above the trailing edge of the wings. Upon removal of the fuselage from the trailer, the ship is lowered until the main wheel is just on the ground. The wings are then extracted from the trailer keeping the leading edge of each wing above the fuselage spar as they are rolled out. Some care is required to ensure that the wings are held sufficiently high to avoid banging the spar stubs. However, this unusual practice readily became routine and was aided by the extreme light weight of the wing panels (approx 100 lbs ea.). As mentioned by “OC”, handling of the wing root is a challenge for the beginner in that there is no spar stub to hang onto. Certainly, either technique or some type of handling aid would take care of this. Overall, assembly is straightforward and is aided by the light weight of the components.
The quality of the components, fit and finish was at least equal to the very best of the German ships. I ran my 2” wave gage over the wings and could not find any noticeable sign of waviness. “Optically”, the wings were near perfect. However, the trailing edge of the left spoiler did not seat perfectly. This condition seemed to disappear in flight. The all-carbon construction gives the ship a very solid and robust feel throughout.
The cockpit is well laid out with the side stick on the right and all other controls accessible by the left hand. There was never a need to “shift” hands in flight as with some gliders. Actuation of the full span flaperon was smooth as silk throughout the flap range. I “really” liked the side stick. Actuation was smooth in both axis and seemed to cause less fatigue on extended flights than a standard stick. However, the Diana’s ultrahigh roll rate does demand a relatively smooth and precise technique.
The cockpit is significantly more reclined than the typical racing class ship. However, I would not describe it as “cramped”. Leg room is a limiting factor for pilots in excess of 6’ in height. However, shoulder, hip and elbow room were all much more generous than my Discus A. The in-flight adjustable headrest was a nice feature. However, another inch or so of leg room would be nice for taller pilots. As mentioned on the NG, I did fly most of the contest barefoot. This did provide a little extra leg room, but more significantly, my white tennis were causing very distracting reflections. A good pair of darker colored deck shoes would have solved this problem without compromising leg room. Ventilation is good with a high volume demister in the nose as well as an “aimable” vent located on the cockpit sidewall near the control stick. I did note that the nose vent, if left in the full open position, becomes unacceptably loud over about 80 kts. However, when the flow is “throttled back”, for higher speeds, it provides adequate ventilation and is very quiet.
Visibility in the Diana is outstanding. With the reclined seating, forward and upward visibility is excellent. Behind, you can see the horizontal and up front, a quick rock of the wings easily reveals any hazardous traffic which may be ahead and directly below.
In flight the Diana is very pleasant. I have never flown a glider with such low adverse yaw characteristics. Full rate (ie. 3 seconds – 45 to 45) rolls can be done with only 2/3 rudder. The resulting maneuverability provides a competitive advantage in centering and rolling in and out of thermals. The Diana offers the option to roll 90 degrees into a turn, change your mind and roll back onto course without delay or significant penalty. “ZJ” was recognizable to other pilots from some distance simply by the extremely agile manner in which the glider maneuvered.
Performance: Based on my experience in Uvalde, the Diana was equal to the best of ASW-27’s and V2’s throughout the envelope. The ship did seem particularly good in the important 90 to 110 knot range. On one particular 55 mile, 110 knot, dead heat final glide, the Diana beat a well-flown, heavy, ’27 home by a comfortable margin. The Diana is limited to 10.3 PSF, which was perhaps a small disadvantage in Uvalde. Another pound or so would have been nice under some of those incredible cloudstreets.
Thermalling is a joy because of the maneuverability, visibility and turn radius. 48 to about 53 knots seemed to be about right at gross weight. In the larger gaggles, I could sometimes core the thermal in a much smaller diameter and outclimb many of the ships. I never once had the sense that any other ship, including the V2, had any advantage in climb. I often ended up on the top of the weak pre-start gaggles supporting my opinion that the ship would be excellent in light conditions.
The contest stats show that I was within a few tenths of 1% of the winner’s score on the AST days, but was about 5% off the mark on the PST’s. My continuing PST brain disconnects dropped my overall ranking on the final day from 3rd to a still respectable 5th. Certainly, the Diana can drag race with the best of them! Thanks again to Jerry Zieba for entrusting me with his beautiful sailplane!
David Mockler aka Discus Driver “2XX”
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