- Dopero is
the acronym of Double Pearson Roller. Starting the history is the Roloplan, a kite built in the 1920th by the German company
Steiff.
After the Second World War, this kite was no more available,
but a British kiter, Alexander
Pearson re-designed this kite.
The larger main sail added pull, the aft sail was reduced
without loosing stability. This new assembly is easier to
set. He named his kite the Roller. Nowadays it is often reffered as Pearson Roller.
- In the 1990th, a fine German kiter and
kaper, Ralf Beutnagel wished to combine the ability of the Roller with more
pull, and to give it more sail area, he had the idea to
design it with two longitudinal spars. The Double
Pearson Roller was born. He named
it Dopero.
I
have choosen this size because the pull is sufficient in
4 to 5 m/s winds, and for wind speed under 4 m/s I have
the Crico 3.6 which is more efficient.
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This
kite has a low wing load ratio (weight/surface), giving
it low wind flight ability. As a flat kite, like the Rokkaku,
it has almost no drag, and is flying with a high line angle.
Its
drawback is the miss of a keel. It may happen in some circumstances
that it slides far on a side and do a loop, or even worse,
go for a dive. To prevent this, a kite need some drag, and
some keel effect. Some kiters have added keels, or funnel
shaped sails, or drogues. But none is satisfactory.
For
this reason, I have designed a double vane keel, which is
more efficient than a normal keel. It adds a little more
drag, but not as much as a drogue, so it keeps flying at
high angle. Then, the angle between the two keels gives
the maximum efficiency of a vane, and force the kite to
keep its orientation in the wind.
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