Sopwith Pup (oz6871)

About this Plan

Sopwith Pup. Radio control scale model WWI fighter biplane model. For .19 power. Scale is 1/6.

Quote: "Build and fly this giant radio-controlled World War I fighter. Sopwith Pup, by Cal Smith.

BY 1915 THE WAR in the air over the Western Front was beginning to develop the terrible things which were to come. No longer did the airmen on both sides merely wave to or take pistol pot-shots as they passed each other on their observation flights. Thanks to Anthony Fokker's successful development of the fixed forward-firing synchronized machine gun, the Germans were able to gain mastery of the skies over the battlefronts. The Fokker monoplanes were shooting down Allied aircraft with alarming regularity.

To offset this German advantage, the French, late in 1915, equipped their Nieuport 11 Scouts with guns mounted above the top wing's centersection and firing over the prop arc. Thus they were able to meet the German Fokkers on somewhat more equal terms.

During the spring of 1916, a new type of airplane, the Sopwith Pup, went into action on the English Sector of the Western Front. It quickly proved to be equal to or better than the Fokker monoplanes and Albatros scouts, The Pup was the first Allied aircraft designed specifically to carry a fixed synchronized machine gun. Its design was simple and sound, and it was considered safe and easy to fly. The Pup was fully aerobatic due to its excellent balance and very low wing loading of 5 lb/sq ft (glider class). It had a good rate of climb of 650 ft/min, and could maneuver well at altitude.

First Pups powered with the 80 hp LeRhone rotary engine had a top speed of 106 mph. Landing speed was 40 mph or less, giving it good small-field performance. Later models were fitted with the 100 hp Gnome Monosoupape rotary, which upped performance a bit. Overall the Pup bore a strong resemblance to the earlier Sopwith 1-1/2 Strutter and Tabloid Scout and seemed to have inherited the good features of both of these excellent aircraft.

Pups saw service with RNAS (Royal Naval Air Service) No.3, 4, 8, 9 and 13 Squadrons and RFC (Royal Flying Corpgi) Squadrons 46, 54 and 66 along the Western Front accounting for a goodly share of enemy aircraft from the spring of 1916 until the end of 1917. By then the Little fighter, outclassed by heavier, more powerful, newer German aircraft, was assigned to less vulnerable duties.

But the story of the valiant Pup did not end with WWI's end. In 1919 Sopwith produced a modified two-place version for the civilian market. This airplane was called the Dove and eighteen were built. One of these somehow survived the rigors of the years, including another World War (2) in England. Just after VJ Day this plane was completely restored and converted into a replica of the original 1910 Pup. Today, a part of the famous Shuttleworth Collection of vintage aircraft, it is in full flying condition.

In the USA an accurate reproduction Pup has been scratch-built and flown by Californian Joe Pfiefer. Several other Pups are under construction by experimental home-builders.

The Pup Model: Simple construction and its many straight lines make the design most appealing for a model builder. She has enough scale dihedral for good inherent stability. Both wings are equal chord, thus we need only a single basic wing rib pattern.

The model is scaled at 2 in to the foot. Every effort was made to simulate the construction of the full size airplane. You will find fabric cover and planked surfaces in their proper places. We do not claim the model to be a 100% Smithsonian-type non-flying scale version since some departures were made as noted for simpler building and better flying. For those interested here are the changes: Wing rib spacing is uniform which differs slightly from scale; however, there is the correct number of ribs. Leading edge is planked rather than having a false rib between each full length rib. Wing spars are in scale position; wing ribs, which scale thickness, are flat-bottomed rather than undercarnbered. Certain rigging omitted includes the flying and landing wires between wing struts and fuselage. Dihedral is increased to 4°, but the scale 3° should be adequate. Horizontal and vertical tail areas are increased and stab has thick symmetrical airfoil rather than thinner scale section.

Span is 53 inches. Length is 39-3/4 inches, Wing area is 200 sq in. While weight may appear high at 5 lb, 8 oz, we still end up with a relatively light wing loading. Nearly one pound is in nose ballast, a necessity for a model with such a short nose moment arm. This is the one unfortunate feature of most WW1 scale planes. Their short noses pose a knotty design problem - how to get proper longitudinal trim? Answer: via ballast or a lifting tail surface. We prefer ballast to gain a normal CG position, since the lifting tail tends to make a model tuck-under in a high speed dive.

Our Pup is not a roar-and-zoom crowd-scattering type. Since the lower wings plug-in and are rubber band retained, excessive speed might set them adrift - we haven't attempted to find out. The Pup is a fine pattern maneuver model - with throttle control, circuits and bumps would be a delight. The biplane makes ROG takeoffs as though on rails and in a most realistic fashion. The tail slowly comes up to near level attitude before the model breaks ground, Those big wheels roll over rough ground easily..."

Supplementary file notes

Article, thanks to Pit.

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