Flying The Old Planes - Part 6: Fokker DR.1

[Pips 5]

Extract from the book "Flying The Old Planes" by Frank Tallman.

 

Because of its step-on-step appearance, the Fokker DR1 Triplane at first glance has all the grace of a blacksmith lifting an anvil. But in its short-lived time of combat over the Western front, its awkward appearance belied flight characteristics as nimble as a nervous hummingbird.

 

A unique machine from Sopwith’s house of wonders provided the inspiration for Mr. Fokker’s flying Venetian blind. The inability of the Albatross and Pfalz fighters to dogfight with this startling innovation forced the German High Command into a reappraisal of it’s own fighter aircraft.

 

The Flugzengmeisterei sent a letter to the German manufacturers on the 27th July 1917 requesting that they submit bid for a triplane, and AEG, Brandenberg Pfalz, Roland and others built prototypes. Yet months before the competition and bids at Adlershof, Fokker had in his usual tour of the front visited Jasta 11 to find only one thing on their minds: the sparkling performance and outstanding fighting characteristics of the Sopwith Triplane. In one instance an extremely courageous and foolhardy pilot of the RNAS Naval 8 (the great Australian ace Robert Little) had attacked eleven Albatross D.III’s and had outmanoeuvred the entire German Group.

 

NB: The battle is described in the Sopwith Triplane thread.

 

Because of Fokker’s Dutch nationality and enviable business success, he was resented by the German manufacturers and got little support from them. He waged a constant war of supply and demand, and from necessity developed material sources that were undesirable or unavailable to the other German firms. With the full production of the reliable Mercedes and BMW water-cooled engines swallowed up by the manufacturers Albatross, Roland etc, Fokker had to look elsewhere for a power plant. Fokker located seven hundred superb Swedish Thulin copies of the French 110-hp Le Rhone stored at Adlershof, where they had been written off by the Germans as out of date.

 

With the rotary engine as the base, Fokker quickly came out with a triplane design that in no way resembled the Sopwith craft, other than for it’s three wings. All three wings were full cantilever, with the lower two bolted directly to the fuselage, while the upper stood on two vees and was wire-braced. At a time when most spars were routed sections, Platz came out with a built-up box spar joined to another box spar with a top and bottom plywood web. The double spar thus joined is light, but large enough in appearance and strength to be the ridgepole in a Jacobean manor house. The fuselage was typical Fokker, with light welded tubing, wire-braced. The gear was streamlined tubing, with ball sockets pinned for security (like the fittings on the Pfalz D.XII) and with the small wing airfoil between the gear, which created enough lift in itself to carry more than the weight of the gear and wheels.

 

Fokker flew the first triplane and promptly sent it back for Platz to balance the tail surfaces and ailerons. After the Adlershof trials, where the test pilots rejected the safe but birdlike flexing of the wings, Fokker wisely added an outboard jury strut that attached to the wings rather than go through them as in the Sopwith Triplane.

 

Ordered into production the first two triplanes in August 1917 became the pet loves of Werner Voss and Manfred von Richthofen. Voss was to achieve immortal fame in the Triplane in his epic battle with some of the best pilots of 56 Squadron RFC, including James McCudden.

 

Shortly, two accidents put an instant hold on production. Heinrich Gontermann, the renowned ‘sausage busting’ leader of Jasta 15 and victor over seventeen balloons and twenty-two aircraft, was killed in full view of his Jasta when the top wing of the DR1 came off in aerobatics directly over his airfield. Two days later a pilot in Jasta 11 dies in the same way. Richthofen grounded his airplanes before the investigating committee arrived, and on opening the wing structure they were appalled to find workmanship on the spars so slipshod as to be almost sabotage, and other spars so badly affected by moisture as to have the strength of a wet cigarette. Months were to go by before the modifications had been completed and the DR1 was again in full production.

 

Although several DR1’s were captured and tested at Farnborough, no truly accurate plans or figures have been discovered. And none of the captured DR1’s survived long after war’s end.

 

With Hitler’s rise to power the Richthofen squadron was reactivated in the mid 1930’s. With the commissioning ceremony just days away, a real Fokker DR1 was found languishing in a barn, and another shortly after. The experts who saw it felt both aircraft were genuine Fokker built triplanes. To inspire the revived Luftwaffe, Hitler commissioned a motion picture on World War One, unblushingly filled with propaganda about a German squadron flying triplanes. There are some lovely flying shots of the Triplanes that can be seen in this film. They are in death-defying combat, with modern Bucker Jungmans thinly disguised as Allied SE5’s. Sadly both resurrected triplanes were destroyed in the bombing of Germany in World War Two.

 

Although there are no genuine DR1’s left, there are at this time at least five replica’s flying, one even with a rotary engine. I have seen most of them, but so far have only flown ours. Reports vary considerably on their characteristics, and at least one owner admitted to me that he enjoyed flying it about as much as if he had climbed into a hive of bees in a bathing suit.

 

Two gentlemen with the dreams of Richthofen and the patience and dedication of Christian martyrs, Tony Bright and Dutch Durringer, were responsible for the original construction of the DR1 now in our Movie of the Air Museum at Orange County in Santa Ana, California. The construction took several years.

 

Facing all builders of replica aeroplanes of this period is the inescapable fact that original engines for WWI are very scarce. Even if you find a modern engine that can be squeezed into the traditional cowling and that has the same rated power, you still do not have the necessary slow-turning propeller with the horsepower developed at 1200 – 1400 rpm (instead of 2500 – 3500rpm), which give all WWI aircraft their unique characteristics.

 

The only American engine that has a rotary facial area and sufficient horsepower was the 165-hp Warner engine, and they are getting exceedingly scarce, but we found one. Basic construction of our DR1 followed closely the original in all detail, with welded steel tubing, wire bracing and box spars.

Before I bought the DR1 from Tony and Dutch I had occasion to rent it for a major air show we were doing. We wanted a World War 1 combat act. Arriving to pick it up I found it painted a dull barn door red, with the wrong type of crosses for Richthofen’s aircraft. Otherwise, it looked every inch like the original. I was eager to fly it, and began my pre-flight checks.

 

Because of the cantilever construction, the most important points to check are the centre section struts, the gear shock cord, and the bracing struts on the underside of the tail. Swinging into the cockpit past the cut out in the middle plane, one wonders what happened to the world ahead, for you can only see to the sides and rear. Controls are straightforward.

 

The Warner is a lovely engine, and it started on the first pull, but because of the limited visibility taxiing was a chore. Checking controls for freedom of movement and checking mags, I turned onto the runway. My rudder became effective in about fifty feet of take-off roll and the elevators brought the nose onto the horizon, so that I could see ahead for a change. The Triplane is airborne in about three hundred feet (with a true rotary it would do that in half the distance). The climb out was at 55 mph, and as I begin a climbing turn I felt ailerons as stiff as a boiled shirt. You very nearly need both hands for the ailerons.

 

Climbing up to altitude and settling down for an hour cross-country, I was struck again by the in-flight appearance of the upper wing so far above and so lightly hung on. I was cruising at a pleasant 98 mph. Getting used to everything except the Mach truck-like ailerons, I stalled the plane, and it fell through at about 50 mph, usually dropping the right wing. Recovery was easy and loss of height slight. Putting the bird in a Lufberry circle, I could see how you could cut the circle small enough to nearly chew your own tail off. The ailerons may be stiff to use, but they do bite the air, and the rudder virtually whips the aeroplane around. In a climbing vertical reverse, the three-wing concept worked well.

 

In a fit of daring equal to grabbing a leopard by the tail, I decided to try a loop. Picking up to 120 mph, I pulled up, but because of the placement of the wings it was hard to orient with the horizon. It was a most uncomfortable feeling. Unfortunately I was a little slow and did not pull tight enough at the top, and barely managed to get over. As the Triplane fell through, I wondered whether the whole stack of wings might not collapse like a club sandwich being sat on by a fat lady. My nerves took longer than the DR1 to recover, but vowed to try again once I had gained my breath. Second time I was more forceful, again entering at 120 mph but this time really hauling on the stick. Almost before I knew it the DR1 had whipped up and over in a very tight loop, with almost no rudder required. This is an airplane that needs to be flown forcefully, no tiptoeing around.

 

Having had enough for one day I let down into the traffic pattern for landing. Choosing to land on a dirt strip, I glided in, and nose down had good enough visibility so that I didn’t feel I was conning a nuclear sub. Flaring out, the DR1 loses speed fast, levelling down at about 45 mph with a rather wobbly feel, and blanking out almost completely of the tail surfaces, so much so that as you are rolling along you might as well have a broomstick for company in the cockpit.

 

Several years went by before I climbed into its cockpit again, now as its owner. The DR1 has gone through a painstaking development process equal to the Saturn rocket and looks infinitely better in correctness of colour and markings. Moreover it now has infinitely better aileron control than it had originally, due to replacing the wrongly routed control cable and the aileron hinges. It’s now a fun aircraft to fly, with beautifully light ailerons that are so positive that to change direction one simply has to look in that direction for the DR1 to go. The rudder is as powerful as ever, and in even gentle turns you can feel the planes gripping the air and wanting to turn more steeply. The roll rate is good, but the fun thing to do is the flat turn just using full rudder. Loops, Cuban 8’s, Lufberry’s, wingovers all are easily performed.

 

Flying the DR1 for any length of time though can get tiring, as there is no tail fin. A large powerful rudder on the end of a short fuselage makes for continual concentration to keep the aircraft from yawing one way or the other. Even so if it wasn’t for the poor(ish) visibility it would be as good as the Sopwith Triplane, although that aircraft is just that much easier to fly, especially in landing. But one adapts. I now make all DR1 landing wheels first, dropping the tail only late in the landing run, with a prayer each time to Icarus or other flying gods to keep me straight.

 

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STATS: From "German Aircraft Of The First World War" by Peter Gray and Owen Thetford; and "Fighter Aircraft Of The 1914 - 1918 War" by W.M. Lamberton and E.F. Cheesman.

 

Empty Weight: 406kg (893 lb)

Loaded Weight: 586kg (1,289 lb)

Engine: 110-hp Swedish Thulin Le Rhone copy)

Max Speed:

185 km/h (115 mph) @ 1,000m (3,280 feet)

165 km/h (103 mph) @ 4,000m (13,120 feet)

128 km/h (80 mph) @ 5,000m (16,404 feet)

Climb:

2.9 minutes to 1,000m (3,280 feet)

5.5 minutes to 2,000m (6,561 feet)

9.3 minutes to 3,000m (9,842 feet)

13.9 minutes to 4,000m (13,121 feet)

21.9 minutes to 5,000m (16,404 feet)

Ceiling: 6,100m (20,013 feet)

Endurance: 1 hour 30 minutes

Armament: Two 7.92mm Spandau LMG 08/15

No’s Built: 320