Stinson 105

That’s a lot of aeroplanes, so I’ll say it again: I reckon the Stinson 105 was the best.

This is because it handles more nicely than most of its contemporaries, has a roomier cockpit with side-by-side seating (greatly preferred, especially by females) and cruises comparatively quickly and economically, while retaining excellent short field performance.

Maintenance is simple, and most spare parts can still be obtained easily (primarily from Univair) or fabricated locally.

Just 11 Stinsons are on the VH register, although there are still quite a few in the USA.

They don’t change hands often, but take my word for it, they are worth seeking out.

“ It handles more nicely than most of its contemporaries, has a roomier cockpit with side-by-side seating and cruises comparatively quickly and economically.

” Contemporary adverts proclaimed: “Never before in the history of aviation has an airplane been so widely acclaimed and accepted as has the Stinson 105.

Equipped with slots, flaps, hydraulic brakes and powered by an 80hp engine, it cruises with three persons at 109 mph.

It’s the plane of the year (1940).

See it… fly it… buy it…’ At US$2995 it wasn’t cheap, but you get what you pay for, and even then, it represented good value for money.

I came to fly this aeroplane thanks to Mike Lodge, a former BA colleague of mine.

Now retired, he is now a glider tug pilot and also owns a rare Slingsby Eagle glider and a classic K6E sailplane.

Mike bought his Stinson four years ago for £15,000 (about A$35,000), with another £9000 (A$21,000 or so) recently spent on a complete engine rebuild.

The Stinson 105’s structure was entirely conventional for its era.

The fuselage is a dependable and strong cage of welded chromemoly (not mild) steel tubing, faired to a more streamlined shape by wooden cap strips and then covered with fabric.

Two doors allow access to a roomy cabin which today has onlytwo seats (with a generous 0.

378m3 baggage area), although originally a third occupant could be accommodated seated crosswise on a removable seat in the rear.

Dual solid plank spruce spars with stamped aluminium ribs and alloy sheet leading-edges with fabric covering form the advanced NACA 4412 aerofoil (also used on contemporary Aeroncas, Harvards, Zlins, Lockheed’s Lightning and Constellation, and subsequently adopted by a number of homebuilts, including Jabirus, among many others).

The Stinson’s wings originally had a single fuel tank in one root, and dual streamlined struts support them.

Unusually, to give docile stalling, there are fixed slots on their outboard leading edges, ahead of the ailerons.

These slots would become a feature of all future Stinsons.

The three-position slotted flaps were another innovation, said to reduce stalling speeds by a full seven knots.

The unusual, low drag cantilever landing gear has a wide track, with oleo/spring shock struts mounted inside, under the cabin floor to minimise drag, and hydraulic toe brakes (a novelty in the era of cable operated fixed heel brakes).

The tail group was also all cantilevered, with a ply-covered wooden tailplane and a welded steel fin, rudder and elevators.

Most tailwheels take their steering from the bottom of the rudder, via separate horns, but this Stinson’s Maule tailwheel is steered direct from the pilots’ pedals via separate Bowden cables, a slightly unusual system which nevertheless works well.

Initial examples of the Stinson 105 had quite a comprehensive standard equipment list (including a fire extinguisher and first aid kit), although starter, generator, radio, steerable tailwheel, wheel spats and landing lights were originally optional extras until incorporated in all examples after 1940.

Thanks to its dual, car style doors (which unfortunately don’t clip open) the baby Stinson is easy to enter, and inside the relatively high, wide cabin, there’s plenty of room for both occupants and baggage.

Both simple, non-adjustable, low backed seats have fixed lap-and-diagonal straps and have been re-upholstered in leather.

The rear part of the cabin originally contained a single, sideways facing seat, but this has been removed, giving a very large baggage compartment.

The rear panel of this is removable, allowing good access for inspection of the whole fuselage interior.

Folk more used to modern Pipers and Cessnas (except the floatplane variants) might be disconcerted by the four slim tubes and central divider cris-crossing the windscreen, but these were pretty standard for the period, and one soon gets used to ignoring them.

There are dual, nearly circular control wheels, but only the left pilot’s has a radio PTT button in its centre, and only his pedals are fitted with toe brakes (although a modification is available to install them on the right, too).

The unusual parking brake lever is on the floor between the pilot’s legs.

To lock the brakes, you press the pedals hard and rotate the lever 110 degrees anticlockwise.

To its right is the slotted flaps’ short lever, which extends them to four positions.

Since owner Mike Lodge does not know the exact deflections, he refers to them as flap 1, 2 and 3.

Instruments are mostly historic, if not antique, and scattered around three separate matt black panels, apparently at the installer’s convenience rather than to any ergonomic plan.

The old fashioned artificial horizon and horizontal French DG are both powered by an under-belly venturi, rather than a modern vacuum pump.

Up on the coaming are two concessions to modernity – a small GPS and a vertical card compass.

The left/right/off fuel tank selector is on the left sidewall.

Piper pilots beware, its short head, not the long tail, points to the tank in use.

Original 105s had a single, 57 litre wingroot fuel tank, but this one also has the optional second unit in the other wing, giving a total of 113 litres.

With a 717kg maximum takeoff weight, G-AFYO’s 469kg empty weight allows a 248 kilo payload, or two eighty kilo men, full (81.

6kg) tanks and 6.

4kg of luggage.

A normally sized male/female couple could take over 25 kilos of bags with full fuel, which is truly exceptional for this class of two-seater.

At least partly thanks to their many ball bearings, the Stinson has nice, light controls, with remarkably good handling for its era.

This example’s performance is better than a standard 105’s because it has a bigger Continental C-90 engine, complete with electrics and starter (the original A-75 and some C-85 powered versions were hand started).

So the fire-up is Continental-simple, after a quick squirt or two of the primer.

Releasing the brakes with that unusual little black catch on the floor, I carefully squeezed the big yellow throttle knob and we gently moved forward.

The undercarriage’s nice, firm suspension and direct, positive tailwheel steering are handy, because you need to weave when taxying, owing to the short body’s nose-up stance.

Like most other Stinsons, this one has a heavy tail, thanks to the forward position of its main landing gear legs, so it’s unlikely you could pitch it onto its nose under heavy braking.

Pre-takeoff checks are straightforward (but include lowering the first notch of flap) so I lined up on Mike’s airstrip, gradually opened the throttle, and carefully applied a little pressure on the right rudder pedal.

After a few seconds of steady, sure acceleration, we lifted off at around 40kt in perhaps 200m, whereupon I immediately rolled into the required left turn for noise abatement.

Accelerating to 60 in ground effect, I retracted the flaps, using the stumpy lever between our seats.

There was a very slight sink during retraction, so I reached up to the ‘window winder’ elevator trimmer in the ceiling.

This is quite sensitive, because its full range of movement is only 180 degrees.

Climbing at 60kt, we easily exceeded 500ft/min, and I reflected on the remarkable takeoff performance from this short, 400m airstrip, considering the little Stinson’s low power.

Presumably, this is because, although the aeroplane looks short, almost dumpy, it has surprisingly long wings – almost as long as a Cub’s, Aeronca’s or Taylorcraft’s – giving it a nice, low span loading, for good field and climb performance.

Once above circuit height, I discovered that, at least partly thanks to their many ball bearings, the Stinson has nice, light controls, with remarkably good handling for its era.

Surprisingly, considering its longish wings, it has a good roll-rate although yes, with the expected attributes of long wings and a short-coupled body, you do need to keep half an eye on the slip ball.

If you don’t keep this centred, the aeroplane is inclined to fly along quite happilywith that ball half a thickness displaced from the middle of its tube.

Despite the nicely shaped Frise ailerons, some rudder is always needed to coordinate turns, but this is not an overly noticeable imposition.

Surprisingly, considering its short fuselage, the Stinson displays very positive pitch stability, so it’s easy to fly hands-off for extended periods.

It also has good yaw stability and, more unusually, positive roll stability, so you would never need an autopilot.

It even rode well through the numerous bumps of a particularly lively day, despite those long wings.

As well as the good downward visibility you would expect from its high winged configuration, the Stinson 105’s particularly high set wing and slim door and window surrounds also give it excellent sideways visibility.

This eclipses most other side-by-side types like the Aeronca Chief, Cub Coupe and Taylorcraft, in every one of which all but the shortest pilots have to double over and twist their heads around to see sideways.

Unfortunately, those diagonal windscreen struts are a trifle distracting although, due to their narrowness, they do not much hinder forward vision.

Setting Mike’s recommended cruising power of 2350rpm gave us 85kt IAS (for 89 TAS) at 2500ft.

Mike usually reckons to cruise at 90kt, burning less than 25 litres per hour, and giving him a generous safe endurance of six whole hours or well over 500nm range.

Stinson 105 History And Variants

Eddie Stinson was one of America’s earliest aviation pioneers.

STINSON 105

(Technical specs)
Powerplant
One Continental C-90
engine producing 90hp
(67kW) at 2650rpm.
TBO 1800 hrs. Propeller:
Sensenich M76A 74 by 42,
two-bladed,
all-metal, fixed-pitch
propeller.
Performance
(Manufacturer’s stated)
Max speed (4800ft) 109kt
Max cruise (4800ft) 104kt
Stall, full flap 43kt
Sea level climb rate
509ft/min
Service ceiling 12,000ft
Max range (45 min reserve)
681nm
Max endurance (45 min
reserve) 6½ hrs
Weights
Equipped empty 469kg
Max takeoff 717kg
Standard fuel 57 litres
Max fuel 113 litres
Dimensions
Wing span 10.36m
Wing area 14.4m2
Length 6.74m
Height 1.98m
Web resources
Spares from Univair
www.univairparts.com
International
Stinson Club:
www.aeromar.com/swsc

Taught to fly as early as 1912 by one of his sisters (both of whom were pilots), by the mid 1920s he was building respected aeroplanes.

His Wright Whirlwind powered 1926 cabin biplane Detroiter incorporated now commonplace Stinson invented innovations like differential brakes, an electric starter and a heater! After the runaway prototype hit a hot-dog stand, he invented the parking brake, too.

By 1927, Stinson had switched to similarly radial equipped strutbraced, high wing monoplanes with up to six seats.

These were initially also called Detroiters, but later renamed Stinsons and Juniors, and quickly started winning races and setting records.

The breed quickly gained a reputation for performance and dependability at bargain prices, and many were used as small airliners and executive transports (the Mars family, of Mars chocolate bars fame had a Junior).

By 1930, Stinson had been financed by the huge Cord Corporation, and started building a succession of big, 11‑seat tri-motor Air Liners.

These were followed by the great, gull-wing Reliant.

Unfortunately, at the age of 38 when, with 16,000 flying hours, he was America’s most experienced pilot, Stinson was killed in a flying accident on January 26 1932.

Late that decade, Stinson’s company realised the world needed a smaller, lighter, more economical two/three-seater, so it designed this Model 105, said to be designated for its cruise speed in mph, but also known as the HW-75, for its high wing and original 75hp (56kW) Continental engine, later enlarged to 80hp (60kW).

Certified in early 1939, 277 Model 105s were built before America eventually joined the war (although some sources say 535 examples were built), the factory turning them out at a rate of three per day.

Film star James Stewart bought one, and so did Howard Hughes, Roscoe Turner and Gulf Oil.

The Model 105 was soon slightly enlarged into the four-seat Model 10 Voyager with a choice of bigger engines.

A total of 775 were built with 80hp (60kW) Continentals, 90hp (67kW) Franklins or 75hp (56kW) Lycomings.

These also had improved soundproofing, better instrument and control layout and a smoother windscreen profile.

During the war, Stinson Aircraft was bought by Consolidated Vultee (Convair) and the line was developed in several different ways into the O-49 O/L-56, L-5A/B, OY-1 and L-9A Sentinel observation and army liaison aeroplanes, with even bigger engines, all-around glazing and structures modified to make maximum use of ‘non-strategic’ materials.

Because of the wartime rush, exact production figures are variable, but it seems around 3500 were built.

After the war, the Model 105/10 was further developed into the four-seat Model 108 Voyager (also known as the 125 Voyager and Flying Station Wagon), of which there were three sub-types with varying engine sizes.

The final, most powerful 108-3 could be distinguished by its larger fin.

In 1948, Convair divested its Stinson range to Piper, which quickly killed production of all but the Twin Stinson, which morphed into Piper’s Apache and Aztec range.

Pulling the carburettor heat knob before throttling back (these smaller Continentals are notorious for carb icing) I gently reduced speed, to discover that the aeroplane only just stalls power off at 40kt with the wheel fully aft. The Stinson’s flap limit is 75kt, the lever loads are impressively light, and flaps 2 & 3 both cause a slight pitch-up. Each setting lowered the stall speed by nearly two knots, making the full flap stall 35kt, with little warning, but still with good aileron control, thanks to those leading-edge slots. The only way I could get a proper stalling nose-drop in any configuration was to run the trim fully forward (thus increasing elevator effectiveness by deflecting the tab fully up, but at the expense of a heavy backpressure).

Experimenting with a little slow flying, I found the aeroplane would happily fly around clean, with 2000rpm at 50kt, and easily making turns of up to 30 degrees bank in either direction.

Flying 60kt approaches, I discovered I needed a lot of aileron in particular, but also elevator and rudder, to counter the nasty bumps caused by a gusting wind and active convective turbulence. Inevitably, the Stinson’s roll control is not quite so good at low speeds, so the aeroplane is happier making approaches through this low-level turbulence and wind shear with flap 2 rather than flap 3. Otherwise, Mike’s only landing limit is a self-imposed maximum 10kt crosswind. After initially flaring at the usual height, I found it very hard to get the nose high enough for a full three-pointer when using full flap. It was only too easy to touch down in a tail-low wheeler, which is never a good thing, because in that attitude you have no tailwheel steering. It was still quite difficult to three-point with flap 2 (which is surprising, considering that heavy tail), but I eventually achieved this on my third attempt.

Again thanks to the Stinson’s short coupling and stiff undercarriage legs, I needed quick, early jabs of rudder to stay straight, but there wasn’t the slightest sign of the tail lifting under even quite heavy braking.

Nevertheless, every landing stopped within 300m, which is very short, particularly in comparison with its lighter contemporaries.

Taxying back to the hangar, I reflected on this lovely little aeroplane’s extraordinarily effective combination of sterling qualities.

Overall, I was very impressed by this rare machine, which exhibited a great compromise between short strip capability and a reasonable cruise speed with excellent sightseeing visibility and side-by-side comfort. It is both roomier, and a better load-carrier than the Vagabond, which I regard as its nearest rival. I thought it was nicer to fly, too.

If I had known about the Stinson 105 before I bought our little aeroplane, I would certainly have bought one of these instead.