MISS CARSTAIRS’ CHALLENGERS
PARTICULARS OF ” ESTELLE IV” AND ” ESTELLE V” NOW UNIWRGOING TRIALS PRIOR TO TROPHY CONTEST
/JAST month, Miss Carstairs sailed for America, taking with her, her new challenger “Estelle V.” with which she will race for the British
International Trophy at Detroit next month. .
“Estelle IV.” which has also gone to the U.S.A. is, of course, the same boat which Miss Carstairs used last year.
In regard to the latest boat, “Estelle V.”, of which great things are expected, this is 28ft. in length and is 8ft. 8ins. across the beam. Honduras cedar has been used for the planking, and the whole hull is very light, though extremely strong. As in its predecessor, the new boat is powered with Napier aero engines, but superchargers are fitted ; at maximum revs. about 1320 b.h.p. is given off. The drive from the power units is interesting, there being no clutches in the transmission. The drive from each engine is carried from both units through tubular shafts to a gear box. One box houses two pinions and the other three ; this is to provide for the rotation of the two propellers in opposite directions. They are cooled by a special system of circulation of oil, and like the engines have been made by the Napier concern. The normal running speed of the propellers is 5,400 r.p.m., and before the contest different types will be thoroughly tried out. “Estelle V.” carries 160 gallons of petrol. Water
is fed to the cooling system of the engines by means:of scoops, and a gas starter, similar to those used in largeengined aircraft is installed behind the seats in the cockpit. The steering is effected by means of a single forged steel rudder, which, of course, is operated by a wheel. The boat is now undergoing tests on Lake Muskoka, Ontario, Canada.
“Estelle IV.” remains substantially the same as she. was last year but several modifications have been carried out to the craft, principally with the idea of reducing the weight. In her new guise she weighs approximately 4 tons. She has an overall length of 35ft. and measures 9ft. 6ins. across the beam. A different system of engine controls has been fitted. The ” Lion ” engines are the same as on the new boat, but they are not supercharged. The transmission system is arranged in a similar way to that on “Estelle V.”, the drive being direct without clutches of any sort This has been done. because previous experience showed that the engines had some tendency to oil-up somewhat when idling over, and because the clutches proved to be a source of trouble on various occasions.
It is understood that “Estelle V.” will be piloted by Mr. A. W. Hawker, who is her designer, while Miss Carstairs will handle the other challenger.