Moby Dick (oz2923)

 

Moby Dick - plan thumbnail image

About this Plan

Moby Dick. Towline glider, 7 foot span.

Quote: "Seven Foot span contest high performance sailplane. Moby Dick, by Eric Smith.

My clothes became cement smeared for the first time in February, 1946. The lot of my present models is a far from happy one, but how those first kits suffered! By dint of much reading, repairing and observation, I felt competent by the following Xmas to bpiid a model from my own drawing. The first requirement was that it should have what I considered a fine appearance. The second, be easily transportable. The third, be easily stored, The fourth, be free from warps. The fifth, simple construction, and finally, that I should be blessed with beginner's luck in the matter of performance.

Nos. 2, 3 and 4 were accomplished by using straight dihedral and detachable wing and tailplane halves. When not flying, the halves are stored elastic-banded one each side of wooden framesi-and the fuselage is suspended by its tail from the ceiling. No warps have ever occurred. This feature, coupled with positive location of all flying surfaces, makes the usual pre-flight hand-launched trim flights unnecessary.

The building of a true fuselage was made easy by making the two separate halves and afterwards cementing together. The problem of broken skids and bent tow hooks was solved by not fitting them. The completion of the fuselage drawing was coincident with the broadcast of an episode in the story of the famous white whale, then in the schools' programme. One look at the drawing and the model had a name.

Moby Dick and launcher are considered to be doing their jobs normally when a flight of three minutes is recorded from a 328 ft. tow Tine. Its best thermal flights, flying above clouds in each case, are: Take-off, Eaton Bray 3.45 pm, land, Halton RAF Camp, 9 miles, 6 pm; take-off, Eaton Bray 5 pm, land, Barton Airfield, Luton, 10 miles, 7 pm. The model has since been cured of this vice by causing it to fly in very wide circles, its longest flight in this trim being 6 mins.

Moby has been subjected to all the abuses a beginner can impose on his model and has never sustained damage. The wings are in no way distressed when 'looped' off the line, and the fuselage absorbs the subsequent impact with only a slight flattening of the nose block. Even this danger has now been averted by fitting a Mk.II tailplane which enables the glider to flatten out from even this extreme evolution. My model is allowed to fly in its natural left-hand turn; providing it is towed up fast and steep, the turn has no effect on the launch. Speed and pull on the line is just right when a 328 ft line begins to 'sing.'

Trimming. Best results are obtained with wing incidence at 4 deg, tailplane incidence 0 deg, and the model balanced on the rear spar. Trim tab is wedged till the required turn is obtained and then cemented in position. Slight inequalities of incidence between the two wings can be corrected by 'stepping' the wing tongues. The wing fixing was suggested by Zeus (oz10357), the tow gear by Avis and the fin profile by one of Mr Temple's models.

The moderate straight taper wing gives a fairly refined appearance and permits the block method of forming perfect ribs. Since a machine of this type is practically non-adjustable, the 'look right is right' method of design is not good enough, and I laboriously worked out the dimensions from formulae and the side areas by Mr Zaic's practical method. I seemed to have made a big error in one calculation only, that of moment arm-tailplane area, This soon became manifest when the plane was stalled off the line. The stalls, by the time the ground was reached, could only be described as magnificent! As has been mentioned, a new dihedralled tailplane of 40 sq in more area and thinner section has cured this fault. Experienced modellers, who having read everything else in this issue have in desperation waded this far in this article, are warned that it becomes even more boring from now on. Inexperienced modellers are, however, advised to carry on, for I personally have never yet met a modeller so dumb that something cannot be learned from him even if it's only what not to do... "

Quote: "I’ve always liked the look of this plane and it’s a bit 'special' for me. When I was a kid (around 1950), I used to gaze in wonder at all the planes in Aeromodeller that were light years above me in terms of both technical ability and financial means... for me, they must have been created by star designers who were aeromodelling Gods. One of the planes that impressed me was this glider. Then one day, I can’t remember how or why, it dawned on me that the designer/creator of this beautiful plane (Eric Smith) was none other than the proprietor of the cycle shop right opposite my school. I can still remember my amazement today!"

Update 13/11/2018: added article, thanks to RFJ.

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