Flying The Old Planes - Part 4: Sopwith Triplane

[Pips 5]

Extract from the book “Flying The Old Planes” by Frank Tallman, 1973.

 

The father of the Sopwith Triplane was the Sopwith Pup, and according to Oliver Stewart, one of the most romantic chroniclers of World War One flying, these were two of the finest and most widely loved and respected Allied aircraft of that conflict.

 

Sopwith sensibly decided to use the Clerget Rotary engine which, among other qualities, had dual ignition and was an advanced design over the 110 hp Type 9J Le Rhone.

 

Like the Pup, the Tripe used the single Vickers gun for armament, with the padded porthole-like windscreen on the back of the gun. Clearing a jam on this little dude must have involved a frozen face and fingers over the snow-covered western Front, and the pilot must have needed a high-wire artists lack of acrophobia to stand up and play armourer on the jammed Vickers. Several Tripes were fitted with twin Vickers, but the performance hit of the extra weight was noticeable and, with the Sopwith Camel beginning to be delivered in large numbers, the Triplane was relegated to second-line status.

 

Through the history of this unusual airplane runs an aura of very strange dealings and decisions. At the same time that the Sopwith Triplane had been ordered by the RFC, the Admiralty had ordered SPAD VII’s for it’s RNAS. Due to reasons never adequately explained, the Services did a swap and, except for one in the Near East, and another fighting the White Russians in 1919, the RFC never flew the type. The area of doubt that still remains is why this fine aircraft was never placed into quantity production, when it was so evidently superior to anything the Germans (or Allies) had at the time.

 

Like the later Fokker Dr.1, the Tripe used a single I bracing-type strut, although in the case of the Tripe flying and landing wires were also utilised. Time was to prove it a strong basic design which, except for early rigging problems, gave little reason for structural worries.

 

The Sopwith Triplane’s fuselage, gear, and tail surfaces are almost dead ringers of the Pup’s, so they are simplicity with a capital S, and the Sopwith Triplanes wings have two solid spars fifteen inches apart. Although not apparent in most photo’s, there are flying and standing wires, as well as drag wires from the cowling to the wings, and additional wires from aft of the pilots seat forward to the wing structure.

 

The struts, which are of spruce and go through the wings as well as the fuselage in the cockpit area, are of a size and shape of a plank from a hundred-gun ship of the line. Interestingly enough, the trim wheel for the adjustable tail plane is bolted to the centre section strut that goes through the cockpit and fastens to the bottom longeron.

 

The Triplane I flew was built by Lou Stolp for Earl Tavan, a Californian rancher who dreamed of Tripes instead of cattle. Lou is a master builder of the Experimental Aircraft Association. With the valuable assistance of the Hawker Siddeley Group detailed original plans were provided to Lou and his team as well as much needed assistance. Some modernisation changes were made for modern convenience that did not spoil the appearance. For power, instead of the cranky and rare rotaries, a Warner 165 hp radial (with the same frontal dimensions) was substituted. A battery, starter, and generator were included as well. Wire wheels of the proper size and weight were designed and beautifully built, with a brake inside the hub and completely unseen.

 

The basic fuselage was constructed of square steel tubing of the same dimensions and of greater strength than the original wood. The cockpit layout was faithfully identical to the original, as were the wings, controls and all wires. The bracing wires were all of the streamlined type (as were those on original Tripes) and purchased from MacWhyte Company in Milwaukee, which is the only firm in the USA which makes such.

 

Because of it’s height, the Tripe appears rather larger than it is, when it actuality it is only a foot higher than the Dr.1.

 

It was brutally hot on the day I flew the tripe, with a ground temperature of 100 degrees. The Warner started easily, and visibility while taxing out was a pure pleasure after the truly blind Dr.1.

 

I taxied out to the end of the runway, and after running up the Warner, turned into the wind. Pouring on the coal, I left the tail on the ground for about 100 feet, then raised it instantly. I got an unexpected torque swing to the left and went off the narrow grass runway, clipping the growth like a McCormick reaper. Full opposite rudder and aileron brought me slowly back along with a sudden wetness in my palms, and I was airborne with no wind in about 480 feet. Obviously the triplane is heavier than the original (by about 300 pounds) and without the slow, big propped rotary, the performance suffers.

 

Climbing out, I was struck by the typical rotary torque feel that had occurred on takeoff. Rate of climb was approximately 1,000 feet a minute at an indicated 58 mph. The three ailerons on each wing were pure delight and gave this machine a crisp response equal to that of a Stearman or Tiger Moth.

 

I climbed to the aerobatic area in slow circles, feeling out the rudder and elevators, which have somewhat lees positive ness than the ailerons. Stalling speed occurred at 44 mph, and the plane broke gently straight ahead.

 

Wide-open throttle gave an indicated airspeed at 3,000 feet of 92 mph, and, edging the throttle back, I dropped the nose gently for a loop. With 115 mph indicated, I pulled back gently and added full power over the top, where I had 30 mph. The Tripe followed through nicely, but with a loop considerably larger in diameter than the Dr.1. All the way through the flying wires sang like a demented peanut vendor.

 

In slow rolls without an inverted feed system, the Warner cut out at the inverted position, and it was necessary to finish dead stick. Normally you would pick something for a horizon line, but in a roll with the Triplane, you have the feeling of three artificial horizons bars, and you are not sure which one to pick.

 

Cuban 8’s are performed easily, as are climbing reverses, with the rudder proving to be adequate. Rolls and changes of direction are crisp and the aircraft quite agile due to those excellent ailerons. Sustained turns on the other hand leave something to be desired. A turn is not the manoeuvre to use with someone on your tail. The strong point of the Triplane is its rate of climb. It goes up like the proverbial monkey, and when speed drops to around 45 mph if you level out quickly it’ll just sit at that height, without dropping off into a stall or spin. Speed quickly returns and the Triplane is once again responsive and light on the controls.

 

In a mock combat with an extremely able pilot, ex-Major James Appleby flying the Fokker Dr.1, I would have the edge flying the Triplane due to the stiff and slow ailerons on the D.1; but both aircraft have their limitations. The skill and experience of the pilots are more important than the actual physical differences between the two planes.

 

Coming into land, I sensibly chose the grass area and not the narrow surfaced runway. I touched down faster and sooner than anticipated at about 52 mhp. Still I managed to roll to a stop straight ahead, and wiped nineteen gallons of salty water off my forehead.

 

Reflecting on the differences between the Dr.1 and the Triplane I feel that the tripe is infinitely superior. It is more controllable, lovelier on the ailerons, climbs faster, and the roll out on landing is easier. It would have been nice to have flown a Tripe with the Clerget rotary, and see how it performed without the extra 300 lb penalty imposed by the Warner engine. Then again, the Dr.1 was also equipped with the Warner, so perhaps the comparisons are valid.

 

=========================================================================

 

STATS: From “British Aeroplanes 1914 - 18” by J. M. Bruce.

 

Empty Weight: 1,101 lb (335 kg)

Loaded Weight: 1,541 lb (698 kg)

Engine: 130 hp Clerget

Max Speed: 117 mph (188 km/h) @ 5,000 feet (1524m);

112 mph (180 km/h) @ 7,000 feet (2133m);

109 mph (175 km/h) @ 9,000 feet (2743m);

107 mph (172 km/h) @ 11,000 feet (3352m);

104 mph (167 km/h) @ 13,000 feet (3962m);

98 mph (158 km/h) @ 15,000 feet (4572m).

Climb: 1 minute 45 seconds to 2,000 feet (609m)

2 minutes 30 seconds to 3,000 feet (914m)

4 minutes 35 to 5,000 feet (1524m)

7 minutes 15 seconds to 7,000 feet (2133m)

11 minutes 50 seconds to 10,000 feet (3048m)

17 minutes 30 seconds to 13,000 feet (3962m)

22 minutes 22 seconds to 15,000 feet (4572m)

26 minutes 30 seconds to 16,400 feet (4998m)

Ceiling: 20,500 feet (6248m)

Endurance: 2 hours 45 minutes

Armament: One fixed .303 Vickers mg

No’s Built: 178, of which 10 were delivered to the Aviation Militaire

Edited July 6, 2009 by Pips

[Dej 17]

You see! I said she was beautiful and Frank Tallman agrees. Do keep posting these, Pips, I'm finding them hugely enjoyable.

 

Flying the OFF Tripe though, I'd have to disagree with Tallman about turn-fighting. If your opponent is flying level or better still shallow diving then you can stand the Tripe on her right wing and track him round all day practically. And if you don't mind losing some height she can almost reverse turn at the speed of Voss... at least it feels like it... used to throw Albs. off my tail easily that way.

[Pips 5]

I'm surprised that the Tripe didn't draw more comments, given the fascination folks here seem to have for three wings. I have to admit that of the Great War British aircraft she is my favourite! As is the SPAD VII for the French aeroplanes and (God only knows why ) the Pfalz D.III for the Germans.

 

As a balance to Frank Tallman's view of the Sopwith Triplane I thought I would add some other first-hand accounts by those who have flown it. Most are drawn from the books "Sopwith Triplane Aces of World War 1" by Norman Franks or "Sopwith Aircraft" by Mick Davis.

 

Wing Commander Paul Hartman, RCAF (Rtd) - commenting on the Carl Swanson reproduction Triplane in 1968 at the International Air Conference about flying vintage aircraft.

Of all the vintage aircraft I have flown, this is undoubtedly the most pleasant to fly. It possessed stability and control response so good as to be unique, not only for aircraft of that era but also in comparison with many of todays machines. It's positive stability about all three axes, plus the horizontal stabliser that was adjustable by the pilot during flight, resulted in an aircraft that coudl be flown with a minimum of concentration and effort. Indeed, when the aeroplane was properly rigged and correctly trimmed in flight, it could be flown hands-off. The controls were light, powerful and well-harmonised and the aircraft's response to the controls was excellent.

 

As I settled into the seat for my first flight I was again stuck by the simplicity of the cockpit and the paucity of instruments. Airspeed indicator, tachometer and pulsometer; throttle, Tampier lever, fuel cock and 'blip' switch plus stick and rudder was the sum total.

 

The seat of the Triplane is much lower than in other aircraft, and my initial impression on sitting in it was one of very limited visibility forward through an arc of 30 degrees either side of the centre line. However a gap between the wing root of the centre mainplane and the fuselage enabled the pilot to see forward and downward for approach and landing. Moreover once airborne the thin wings offered almost no restriction to overall visibility.

 

The engine was primed, throttle and Tampier levers set, switch on. Contact! The Clerget fired immediately and settled into a rhythmic rattle typical of the rotary and idled smoothly at about 700rpm. I had no intention of allowing this aircraft to become airborne in a three-point attitude, as happened during my first flight in the Nieuport 17. Thus the control stick was held about one inch forward of centre as I opened the throttle. The Tripe accelerated quickly as the power was increased to approximately 1150rpm, and the tail rose at about 20 knots. There was almost no tendency for the aircraft to swing to the left due either to torque or the gyroscopic effects of the engine, and very little rudder was required to keep the aircraft straight during the take-off run.

 

With the tail up and the aircraft in almost level flight attitude, visibility over the nose during the take-off run was excellent. At 38 to 40 knots, the aircraft left the ground and accelerated rapidly to 60 knots. I eased the climb, holding the speed constant at 60. The altimeter indicated 650 to 700 feet as the aircraft boundary was crossed - a distance of approximately 5,000 feet from the take-off point. I had been airborne less than a minute at that instant, so the aircraft has a fair rate of climb. Those watching on the ground told me later it appeared to be climbing like a homesick angel. It certainly felt so to me. I continued the climb to 900 feet, where I levelled off and made a left hand return to the field.

 

During the turn, with an angle of bank of 40 degrees, I became aware that a coordinated entry into the turn had been made without my being aware of it. There was no slip or skid, and no gyroscopic precession was apparent from the engine. The wind blasting squarely in my face confirmed the former, and the necessity to hold a very light top rudder force during the turn attested to the latter. At 1,500 feet above the aerodrome a stall check was made. The throttle was closed and the engine idled at approximately 700rpm at an indicated airspeed of 40 knots. The control stick was fully back. The aircraft was hanging on the properller in a 12 to 13 degree nose high attitude, refusing to stall. I depressed the blip switch, the rpm decreased, and the nose dropped. The ailerons were fully effective immediately prior to either wing drop. As the nose dropped, the blip switch was released and the engine picked up to idle rpm. The height lost during recovery from the stall was 75 feet.

 

After recovery the aircraft as trimmed to glide at 50 knots. The glide was continued to 1,000 feet, where the engine power was set at 1100rpm and a level speed run made. Subsequent corrections for air temperature showed the aircraft achieved a true airspeed of 111 mph.The speed run also enabled a last check to be made of the effectiveness of the adjustable horizontal stabliser as a trimming device. It was a positive and poweful trimming device.

 

A speed of 105 knots indicated was the maximum to which the aircraft was flown. It displayed a slight tendancy to yaw to the left as speed increased in a dive, then yaw to the right as speed was reduced. The yaw is easily overcome with rudder. The landing was straightforward and easy. The aircraft was glided at 50 knots to a height about 15 feet above the ground, at which point the blip switch was depressed and held. The control stick was eased slowly backward to flare the aircraft. It slowly lost height as the speed decreased during the flare, until the aircraft was about one foot off the ground at a speed of about 40 knots. Stick fully back at this pont - a slight sinking feeling as the air speed needle touched 37 to 38 knots - and we're on the ground!

 

 

Captain Foster Herbert Martin Maynard, who served with 'Naval 1' in the Great War.

The Triplane was an excellent machine for fighting purposes, for although somewhat leisurely in manoeuvre, it's extra-ordinarily good climbing powers generally enabled a good pilot to get the better of his opponent in an individual contest.

About the middle of July (1917) I was given a two-gun Triplane to try out. The extra firepower afforded was, of course, extremely valuable. Unfortunately, the extra weight took off so much performance that the machine was of no use in a formation of ordinary one-gun Tripes.

 

A report by a British Third Army AA position, which witnessed Robert Little (Naval 8) attack several Albatross near Arras om 7th April, 1917.At 1845hrs on the 7/4/17 a Sopwith Triplane, working alone, attached 11 hostile machines, almost all Albatross scouts, north-east of Arras. He completely outclassed the whole patrol of hostile machines, diving through them and then climbing above them. One Albatross scout, which was particulary aggressive, dived on him and passed him. The Sopwith then dived on him and then easliy climbed again above the whole patrol, drawing them all the time towards the anti-aircraft guns. As soon as they were within range, the anti-aircraft guns opened fire on the patrol, which turned eastwards, and the Sopwith returned safely. The officers who witnessed the combat report that the manoeuvering of the Sopwith completely outclassed that of the Albatross scouts.

 

Captain Robert Alexander Little, Naval 8.

(he has dived into a mixed fight involving several FE's and Albatross scouts on 30 April at 0645hrs, east of Arras).

An Albatross dived on me from out of the sun. My gun jammed and I tried to break off the engagement, but the HA kept pace with me and opened fire, shooting away my pump and hitting the planes, so then I stopped and stunted. I then got under the HA and stayed there. I turned when he turned and dived when he dived. The HA pilot could not find me.

 

I got my jam clear and fired on the HA, which was about 20 feet in front of me and about 10 feet above. Half the fuselage and engine was all I could see through my sight. I saw tracers hit it. It started to climb, then stalled and went down in a dive, turning slowly. I last saw him at 1000 feet when I lost him in the mist.

 

Flight Commander Raymond Collishaw, Naval 10.The Triplane I found to be a delightful machine - in my estimation much preferable to the Pup. The machine was a private venture by the Sopwiith Company, and the prototype made it's appearance in mid 1916.

 

The three-wing design was adopted to permit the pilot the widest possible field of vision, and also as a means of ensuring manoeuverability. The middle wing was at the pilot's eye level, and interfered very little with his vision. All three wings had a narow chord, and because of this the top and bottom wings blocked off less from the pilot's view than in the case of biplanes. The standard Triplane was fitted with the Clerget 130 hp engine. This powerful motor gave it a speed of nearly 100mph at 15,000 feet, and it could climb to 10,000 feet in just under 12 minutes and had a service ceiling approaching 20,000 feet.

 

Apart from it's good manoverability and rapid rate of climb, which was very good for it's day, the Triplane's main virtue was the extreme altitude that it could attain, and its performance at these heights. Like all aircraft the Triplane had its weaknesses. It was not quite as fast as it could have been, and it could not match a machine such as the Albatross D.III in a dive. Its main failing though was its armament. Like the Pup it only had one Vickers. The German fighters it was pitted against during 1917 had twin guns, and given comparable performance, it is hard to find a substitute for firepower.

 

Six experimental models were in fact fitted with twin Vickers, and I was fortunate enough to obtain one prior to leaving Naval 10. Some of the pilots considered the added firepower would be more than offset by a drop in speed and climb performance at height as a result of the extra weight. Others, including myself, felt that a certain loss of performance would be acceptable in exchange for the extra gun. I found, in fact, that although there was a definite loss in performance over 10,000 feet, it was relatively slight, and having twice the firepower at my command made a big difference.

Edited July 8, 2009 by Pips

[Herr Prop-Wasche 7]

I'm surprised that the Tripe didn't draw more comments, given the fascination folks here seem to have for three wings.

Probably because there is no more left to add, after your posting of these wonderful primary sources!