• Great Airplanes: The Ford Trimotor

    Great Airplanes: Ford Trimotor

    By Andrew Herd (25 June 2004)

    In 1925, the indefatigable Anthony Fokker, wired his Amsterdam works from his New York hotel with instructions to build a three engined version of the Fokker VIIa. The final product was designated the FVIIa-3m and flew on the Ford Reliability Tour, and then after a spell at Wright Field, it was moved to Detroit, where Edsel Ford spotted it. Edsel was so enthusiastic about the plane that he struck a deal to enable Lieutenant Commander Byrd to fly the FVIIa-3m to the North Pole, following which the Philadelphia Rapid Transit Company bought several to run a passenger service between Philly and Washington. The FVIIa-3m and the F-10a Trimotor that succeeded it were displayed at the Chicago Exhibition in 1928 and among the other mixed construction civilian aircraft of the time they stood out as two of the most advanced planes of their time. But Fokker's dominance was not to last.

    In 1923, two years before Fokker sent his telegram, a far sighted entrepreneur called Bill Stout had commissioned the design of an all metal aircraft known as the 'Air Sedan'. This plane had too small a payload for practical purposes, though it acted as proof of concept, so Bill and the Stout Metal Plane Company engineers went back to the drawing board and stretched the Air Sedan into an 8 passenger Liberty powered plane identified as the 2-AT - the AT standing for 'Air Transport'. The 2-AT did sterling service and it wasn't long before it came to Edsel's attention that something more might be made of it, so Ford invested in the building of an airfield and production facilities. The timing was perfect, because a month after Ford Airport was dedicated, the Kelly Mail Act was passed and Henry Ford decided to start a freight air line between Dearborn and Chicago. By the end of 1925, Ford had seen enough that he did a deal to buy Stout out, which is how the Ford Motor Company came to be a manufacturer of airplanes.

    The 2-AT now fades from the story (it faded from history in 1928 when the wing turned out to be structurally weak), but the advent of the Wright Whirlwind radial prompted Stout, who remained at the helm of his former company, to design a three engined variant of the 2-AT, which was known, with Stout's instinct for snappy titles, as the 3-AT. This aircraft had challenging handling to say the least and it was probably fortunate that it was burned out in the fire that destroyed the Stout Metal Plane Factory in 1926. While the factory was being rebuilt, a new trimotor was being designed under the direction of Chief Engineer William B. Mayo - this 4-AT-1 looked so like the Fokker Trimotor that the only way most people could tell them apart was the corrugated skins of the Ford, but however similar the two hulls may have appeared there was a crucial difference. Henry Ford planned putting his design into mass production and the new factory would make it possible to build a new plane every day. As it turned out, that sort of capacity was never needed and only 199 Trimotors were built between 1926 and 1933, when production ceased, sales having been crippled by, among other things, the Wall Street Crash (Microsoft say 198 hulls were completed, but what the hey). Production was split between the Whirlwind engined 4-ATs and the more powerful Wasp powered 5-ATs and by the time it had finished, it was clear that aircraft production would never be the same again.

    It will interest many readers to hear that the Ford Trimotor was not the first all-metal aircraft to be built, that honor belonging to the Junkers G-23, which was a three engined monoplane built in 1924. But the G-23 was a custom built hull far ahead of its time and when Ford threw his weight behind production, it was still an article of faith that aircraft were built of wood, fabric and wires, with even cutting edge models like the Fokker employing partial metal skinning. The Ford was skinned with 'Alclad' - Duraluminum sandwiched between two layers of almost pure Aluminum - which combines the strength of Duraluminum with the rot resistant properties of the softer Aluminum. Every exposed joint and surface was laquered to ensure that the least possible corrosion occurred, which accounts for why such a high proportion of Ford Trimotors have survived. The early cabins were filled with wicker chairs, a luggage compartment and a toilet (advanced stuff in 1926). Large windows provided panoramic views, every passenger having a pull-down shade and later models even boasting electric lighting, but there was a great deal of customisation and interiors varied from spartan to beyond club class.

    The wing was a cantilever bridge design with a thick section and broad chord - which gave it good low speed handling characteristics at the expense of increased drag. Economical cruising speed was therefore around 113 mph and most hulls were flat out at 138, which is the kind of performance which makes headwind component a constant consideration. However, since speed counted for rather less in an age when a safe arrival was by no means assured, this was less of a sacrifice than it might seem nowadays, the irony being that sector times were one of the reasons why production ended; aeronautical engineering had advanced by leaps and bounds and the Trimotor had become a casualty of the very progress it had catalysed. Incidentally, one of the cleverest features of the airframe was that the outer wing sections were standardised bolt on units and the wingspan variations between the various different models were accounted for entirely by the width of the center section.

    Cockpits varied from one model to the next. A common feature was a bulkhead dividing the pilots from the passengers, some planes having a door fitted. All the photos I have seen show dual control wheels fitted on tall columns, which was highly necessary, because in rough weather it sometimes needed two people to fly the plane. The second person wasn't always a flyer and so early cabin crew gained flying experience out of necessity, not least because the gauges on the right hand engine weren't at all easy to read from the pilot's seat, even though they were illuminated at night. The EAA plane depicted in FS2004 is interesting because it has a VSI, which wasn't standard equipment in the original Trimotor; presumably someone had the good sense to shoehorn it in retrospectively.

    I have already mentioned that the Trimotor was heavy on the controls, but one of its more challenging features was that an outboard engine failure at low airspeeds could cause an uncontrollable swing - there simply wasn't enough rudder authority to handle it. Ford were coy about the performance, but it seems that fully loaded, takeoffs took around 300 yards; that figure reducing to a hundred with part filled tanks and an empty cabin. The typical landing roll was 330 yards, though a skilled pilot could stop the plane in less than a hundred if he was determined enough. Of course, all these figures depended on which powerplants were fitted and some Trimotors were highly modified after delivery. One thing is for certain, in the right hands, a Trimotor could be made to do the most surprising things and Harold Johnson became notorious for performing 17 consecutive loops in a standard 4-AT-B. Johnson also flew hammerheads, Cubans and aileron rolls in that plane and used to delight crowds by finishing his performances with a one wheel landing - which doesn't sound too scary until you see the photographs.

    The article is illustrated with some wonderful liveries by Ed Knapp. I guess that many people have passed these by on the basis that they aren't eye catching enough to be worth the bother of downloading, but the reality is that few Trimotors ever wore colorful schemes. Partly this was a sign of the times, but it was also the case that the real Trimotor wasn't exactly the easiest plane in the world to paint, thanks to all those corrugations. I guess it took someone like Ed to see the potential of the visual model, which is one of the best ones Microsoft have ever done - personally I like the restrained schemes, they speak to me of quieter times, when the world was in less of a rush to get ahead of itself. I have never really had an opportunity to say thank you to Ed for the service he has done to the hobby, so I guess this is as good an opportunity to pay homage as any. Just about the only improvement that could be made to any of Ed's schemes would be to tone down the corrugations in the skin a little, as these cause some moire effect at comfortable viewing distances.

    The FS2004 Trimotor has an exceptionally good visual model that captures the character of the plane perfectly. The tin lizzie being the simple design it was, you don't get much by way of animation apart from an opening passenger door, but then the real plane didn't even have flaps, so one can hardly complain. The 2D cockpit is, like all the ACOF planes, something else, with a crisp photoreal bitmap that puts the modern GA planes (and about 80% of the addons we get to see, excepting FlightOne, Captain Sim and DreamFleet stuff) in FS2004 to shame. I really did think, when ACOF was released, that we had seen the end of developers trying to sell sloppily edited low resolution 'art' panels in thirty dollar packages, but still they come. It is hard to say why users aren't more critical, but I suspect the reason is that when it boils down to it, many simmers are happier with a mediocre looking panel in a fast plane than they are with a great panel in a classic. I do reckon that when a developer is trying to sell an addon for profit, they owe it to the consumer to get out there with a camera and come up with a convincing looking replica of the cockpit of an existing aircraft, but what do I know?

    Harold Johnson would not have been pleased with the Microsoft Trimotor, but then I guess the reason he could loop it seventeen times in succession proves that he was a far better pilot than most of us will ever be. Like all the ACOF taildraggers, the plane is a handful early in the takeoff run and it is by no means easy to three point. Chopping an outer throttle before the tail lifts does indeed make the plane yaw uncontrollably and I wouldn't bet the farm on the two engined climb rate. All in all, it felt just like I imagine the real thing does, which is a tribute to Microsoft. Their team spent a great deal of time getting the vintage planes right and when you look critically at the Trimotor it is clear where much of that hard work went.

    Trimotors served all over the world, hauling just about every load you can imagine and some were fitted with floats, crop spraying bars and even skis. They also served as fire jumping planes and military transports in addition to the passenger carrying role for which they were originally designed. There is a surprising postscript to the Trimotor story. In 1953, Bill Stout declared that a new Ford Trimotor was going to be built, with the blessing of Henry Ford II. This aircraft was to be known as the Bushmaster, but anyone who took a sideways glance at it would have known what it was. Between the jigs and the reels it was a dozen years before the first example flew, a second being completed in 1985 - and it is thought that a third, part finished hull exists. Around seventeen Trimotors have been preserved, of which something like half a dozen are capable of flight, which says something for Bill Stout's talent, and Henry Ford's vision.

    Andrew Herd
    andy@flightsim.com