Airtest – Stolp Starduster Too

I am flying the Stolp Starduster Too; this aircraft seats two and is ideal to learn aeros under instruction or simply introduce friends to flying. The dual owners wanted an engine of no more than 180 horsepower (135kW) to minimise costs but also wanted reasonable performance so one partner could take up competition aerobatics. They discovered what many had before them: good Pitts S2s are expensive and rare, Christen Eagles and Steen Skybolts cannot quite legally do aeros two up and Stampes are becoming a little long in the tooth. Then they came across this Starduster. She was the perfect aeroplane: “She was pretty, inoffensive, had softer lines than the aggressive-looking Pitts – we had to buy her.”

From their aeroplane’s excellent finish you would never guess it to be a homebuilt. The parts can be bought in packages called ‘kits’ but it is not a kitplane in the modern ‘pop rivet it together in a fortnight’ sense of the words, being much more a ‘buy the plans and raw materials and learn welding and gluing’ scratch built, do it yourself sort of job. It never ceases to amaze me that American homebuilders might spend the equivalent of over $10,000 on materials for such a project and invest hundreds or sometimes thousands of valuable manhours meticulously constructing their aircraft to then sell it within a year or two (often for little more than the cost of the materials) and go on to building another.

Although inexplicable, this custom works very much to the benefit of fliers like us because there are always lovely homebuilt aircraft on the market at bargain prices. Such a machine was G-BOBT, formerly N690CM. Exhibiting a miraculous standard of workmanship, it is far better finished than most factory built machines yet was constructed by teenager Clinton Anderson who must be quite a young man. As a seventeen year old he bought the plans for this shapely but highly complex steel tube, aluminium, wood, fibreglass and fabric aerobatic biplane and set to work building it. Just three years later he had not only completed the aircraft but his workmanship was to such a high standard that it beat America’s homebuilt best, winning the Reserve Grand Champion award at the Experimental Aircraft Association’s annual Oshkosh rally in 1987. Within months of its triumph he had sold it whereupon it was exported overseas and the current owners now reap the benefits of the industrious youngster’s hard work and perseverance.

The Starduster’s fathers, Lou Stolp and George Adams, designed and built the first of the type in the mid nineteen fifties, flying it in November 1957. Their shapely single seater proved so popular they soon started selling plans and components and were promptly encouraged to make a two seat derivative. Lou began welding on the SA 300 Starduster Too in late 1962 and the finished prototype flew in 1966. Since then the Starduster Corporation has changed hands twice but is still based at Riverside Airport in southern California and for the last ten years has been owned by Bill Clouse. Two thousand four hundred sets of plans have been sold along with seventeen hundred kits. Hundreds of finished aeroplanes are flying in the States with already half a dozen in the UK.

Although from its specifications it might seem just another open cockpit two seat American biplane, its distinctive shape is recognizable at a glance. Standing atop tall wide undercarriage legs the long elegant fuselage has graceful, flowing lines. A closely cowled engine is set well forward on the slim body and instead of simple parallel chord wings its sculpted trailing edges make it look more like a living dragonfly than an inanimate machine. Despite its stylishness, construction follows tried and trusted methods, using a welded steel tube fuselage framework with fibreglass rear decking and wire braced tube tail surfaces and flying controls. The main undercarriage legs are carefully faired inverted tripods pivoted at the lower longeron and using undamped shock cords (bungees) for suspension with looped wire restrainers as a back up should the rubber bands snap. Differential hydraulic discs provide retardation and neat spats reduce the drag.

The staggered, unequal span wooden wings have twin spruce spars. Ply ribs form the traditional Munk M-6 section and are covered, like the rest of the airframe, in modern dacron fabric. The upper surface is swept back six degrees while the lower one has a degree and a half of dihedral and one of incidence. They are braced by twin flying and landing wires, separated by single interplane struts and the top plane is joined to the fuselage by all of eight angled cabane struts. Four wood framed ailerons are used for a good roll rate.

G-BOBT’s engine is a 180 horsepower (135kW) Lycoming O-360 with only seventy hours since major overhaul. Modified with the solid flanged aerobatic crankshaft, pressure carburettor and Christen fully inverted oil and fuel systems, it drives a polished Hartzell constant speed propeller encased in the shiniest imaginable spinner. Fuel comes from two tanks, a 55 litre auxiliary in the upper wing’s centre section and the 113 litre main one in the fuselage ahead of the front cockpit. The fuel selector has four self-explanatory positions: off, fuselage, wing and aerobatic. Since only the fuselage tank has a quantity gauge it should always be used for takeoff and landing. Forgetting to use the aero position is OK for short periods upside down but if you happen to be involved in a long inverted aerial photography session I can attest that the engine will die after about forty seconds on the normal supply, causing you to slide out of view just when the cameraman has you in sight.

Although this aircraft has amassed nearly 300 hours, the aeroplane is still immaculate. Painted in wetlook polyurethane its colours are two tone red on a gleaming white background. However from the application of a vivid starburst scheme to both upper and lower surfaces of all four wings and the tail one has to presume young Clinton was not a devotee of competition or display aerobatics in which it is important to see from a distance whether an aircraft is erect or inverted.

A non slip walkway on each wing root makes entry to both cockpits quite straightforward and once inside the lack of inner sidewalls allows plenty of elbow room. Solo flying is done from the rear but both seats have comfortable upholstery and five point harnesses with backup lap straps. The seating position is fairly upright with feet stretched out ahead so inevitably the rear occupant’s Reeboks end up alongside the front person’s thighs but there is no interference and while comfortably snug, the cockpits are not cramped. Being a VMC machine, the rear panel is limited to a trio of flying instruments – dual scale ASI, altimeter and turn and slip (far safer in an aeroplane used for aeros and spinning than the stupid turn coordinators foisted on us by the Americans) but it lacks an inverted slip ball.

While each cockpit is surrounded by a nice rolled crash pad and protected by a broad tinted screen, this encloses a compass neatly positioned so that luckless pilots can refer to unsightly forehead scars as coming from their reflector gunsights after a prang in the war. Completing the analogy, the long control columns are topped by comfortable offset pistol grips with transmit switch triggers. Throttle and prop controls are installed conventionally on the left sidewall but the unusual elevator trim knob below the rear seat is adapted from a vernier engine control and screws in and out (fore and aft). Finding its sense unnatural, I could only remember which way to turn it by stroking the outside of the knob upwards with the palm of my left hand to relieve stick back pressure. There is no indicator so a swan like movement of the neck is required to check the tab is neutral before takeoff.

Both occupants have full primary flying controls and toe brake pedals but with the exception of RPM and manifold pressure gauges in the front, engine instruments and secondary controls are only available in the back. Waterproofed switches for the electrics share a central console with the radio and intercom. Although there is no parking brake it is easy to keep the pedals depressed for starting which follows normal fuel injected Lycoming practice.

Either the engine’s compression is very good, the airframe is particularly light or the undercarriage is soft, because as the Lycoming fires the aircraft rocks to its beat. Being basically a longer stroke O-320, the O-360 is pretty hefty for a four cylinder motor and generally causes some noticeable low frequency vibration so this oscillation probably stems from a combination of all these factors. Even sitting on two cushions your head is quite low and the rear hole is well back along the fuselage so the forward view over the wide nose and through those eight cabane struts is very limited. You really do have to taxi in an exaggerated weave to see and avoid obstacles from the outset. The aeroplane’s easy, loping gait confirmed my suspicions of a soft undercarriage and made for a gentle ride on the grassy sun hardened bumps.

Opening the throttle slowly to allow the prop governor to catch up, the aircraft accelerates well showing only the slightest tendency to yaw left as it bounds across the tussocks. Bearing in mind the tapering fuselage it is as well to alternate glances out of both sides of the cockpit to avoid instinctively lining up one sidewall with a runway edge and going off at a tangent. More easily controlled than its shorter bodied brethren, the aeroplane is not at all ‘squirrelly’ but rather more ‘kangarooey’ on those long, soft legs. Even with full forward stick the tail takes a few metres to lift, revealing a hitherto unavailable panorama.

Flying off at 52kt (97kmh) a good footful of right rudder is needed in the stable 73kt (137kmh) initial climb. My stopwatch recorded a rate of 1100 feet per minute (336mpm) at the first attempt but this is clearly less than the aeroplane is capable of and mainly due to unfamiliarity and experimental error. Practice should increase this and the solo rate is well over 1500fpm (458mpm).

Since the big rounded windscreens are very effective and the cockpit warm and draught free I was soon able to discard my goggles to fully enjoy the pleasures of open air flying.

The view in level flight is good in all directions but directly ahead so a meandering, sightseeing route would be safer than straight lines on a cross country. Sixty one centimetres and 2400rpm resulted in an indicated airspeed of 118kt (219kmh) but later formation flying with my Champ and the duo’s Arrow suggested that the ASIs overread by 10% or so. Long range cruise at 53cms and 2100rpm achieves an endurance of five and a half hours for a 600nm (1110km) range. Brochure maximum speed is quoted as 150 knots (278kmh) with a 120 knot (222kmh) cruise but without specifying a power setting. At high speed we could clearly hear the wind in the streamlined wires but throughout the flight the engine was inaudible inside our David Clark sound deadening helmets.

The aeroplane is strongly stable in yaw and just so in pitch but quite neutral in roll. Combined with ailerons that are very light at small deflections. Bigger stick inputs make the four ailerons’ presence more noticeable and although a roll rate of 120 degrees per second is available it is at the expense of some effort at higher speeds. Rudder and elevator are nice and light but the rudder seemed lacking in authority in low speed sideslips while fitting a trim tab would quickly remove the constant need for right rudder except when the throttle is closed.

With two occupants and 114 litres of fuel we weighed the maximum of 816 kilograms. Bearing in mind the ten percent ASI error, the stall is presaged by good buffet at 62kt (116kmh) IAS and the gentle break comes straight ahead at 53kt (98kmh) without any hint of a wing drop. If you hold the stick back she wallows and sinks with the nose just below the horizon and attempting to drop alternate wings as if performing a falling leaf. Recovery is normal but a good blast of power will motor it out of the stall with a height loss of less than a hundred feet.

The 130kt (240kmh) entry speed for both loop and slow roll requires a slight dive and lots of rudder was needed in both manoeuvres while the latter really showed up the ailerons’ heaviness. Flying two up tended to highlight the Starduster’s lack of brute power but she easily accomplished all I could ask of her and the owners assured me that when flown solo she performs like the much more powerful Pitts S-2 does dual, with a full vertical roll easily possible. Manufacturer’s G limits are plus 6 or minus 4g with an ultimate of 9g at 770kg but we respected the recommendations of the country in which we were flying which imposes maxima of +4/-2 for safety and we fully utilised these on our sortie.

The Starduster has unlimited inverted capability and, like most types, even with the trim fully forward a fair push is still needed on the stick for level head down flight. Inverted stall speed is around 70kt (130kmh). As in most such aircraft it seemed easiest to approach in a slipping curve at 78kt (145kmh), reducing to 70kt (130kmh) over the fence. Speed control is simple and unlike the Pitts or Spanish Jungmann, the Starduster has plenty of elevator authority for a full glide approach – a comforting thing to know should a forced landing ever be necessary.

The Stolp coped very well on its long soft undercarriage and proved much easier to keep straight than a Pitts or Christen although it was soon evident that proper three point landings require a certain knack. She settles on all three wheels and rolls to a halt without brakes in a few dozen bounds in about 200 metres. Control on the ground is noticeably easier than in its shorter coupled rivals without suffering undue performance limitations and in practised hands she should be capable of competition aerobatics up to intermediate level. For those who have never experienced the delights of an open cockpit or, like me, have gone for too long without blowing away the cobwebs, this is a perfect aeroplane for renewing your enthusiasm for flying.