Flight Test: RANS S-20 Raven
PUBLISHED: 12:54 13 December 2016 | UPDATED: 12:54 13 December 2016
Whether as a taildragger or 'nosewheeler', the Raven would be one to look out for if it were accepted by EASA
Words: Dave Unwin; Photos: Jim Lawrence
So, I’m flying a classic rag-and-tube taildragger, yet this one is fast, quiet, warm and comfortable. Who says nostalgia isn’t what it used to be?
When the opportunity arose to test the latest little taildragger from RANS I jumped at the chance, particularly as it is not only my kind of aeroplane, but it has recently become available as a factory-built S-LSA, which should greatly ease its transition through EASA’s tortuous acceptance process. Another reason for my enthusiasm was that I’d be introduced to the machine by its designer and CEO of RANS Aircraft, Randy Schlitter. Not only is he excellent company, a bit of a polymath and a decent pilot, he’s also very funny!
Walking up to the neat little two-seater, my immediate thought is that although it is quite a handsome aircraft, it’d look even better if the wings and tail had rounded tips (a rounded rudder is now an option).
As I’ve come to expect from RANS, the Raven is both intelligently designed and well made. At first, I wonder if perhaps the S-20 is simply an amalgamation of the sideby-side S-6 ‘nosewheeler’ and the tandem-seat S-7 taildragger (no bad thing as they have achieved combined sales north of 3,300). However, I soon realised the Raven is much more.
It is perfectly conventional in both design and construction. The fuselage is constructed of welded 4130-gauge chro-moly steel tube, while the wing features extruded aluminium tubular spars and stamped aluminium ribs. Most of the metal components are protected by either paint, a powder coating or simply anodised, although the wing ribs, sheet metal baggage compartment and root skins are left as bare 6061-T6. Welding is mostly by the MIG process, although particularly critical areas are TIG welded. Apart from a sheet aluminium leading edge, the wing and fuselage are covered with Super Flite fabric (Oratex is an option), as are the flaps, fin, tailplane and control surfaces.
Interestingly, there is no stitching involved at all, irrespective of whether Super Flite or Oratex is used. The fabric is glued in place and blind-riveted to the ribs. The aerofoil is a Harry Riblet 30-615 section that RANS has modified slightly to work with the S-20’s trailing edge spars. This is why the leading edges of the differential ailerons and flaps are not quite as thick as on other wings which use the same aerofoil.
The manually operated slotted flaps cover about two thirds of the trailing edge and are actuated by Teleflex push-pull cables. The ailerons use cables then bell cranks and push rods at the point of exit from the wing bottom, while the elevator is worked by push-pull tubes via bell cranks. Stainless steel cables drive the rudder.
The mainplane is supported by streamlined aluminium struts, while the tailplane is braced with stainless steel wires, both above and below. Neat touches are the elegant fairings around the flap and elevator drives.
Gaining full access to the engine bay on the test aircraft is a little onerous, as removing the fibreglass cowling (carbon fibre is an option) requires undoing lots of fasteners. There are half as many on production aircraft! There is a small access hatch on the starboard side for checking the oil and coolant, and an LED landing light located within the cowling.
Engine options are numerous, and include various versions of the Rotax 912 and 914, the 116hp Lycoming IO-233, 180hp Titan 340 and 180hp ULPower 520. The test aircraft has a Rotax 912ULS and its 100 horses are converted into thrust by a Whirlwind ground adjustable three-bladed prop, while the fuel is carried in a pair of tanks located in the wingroots with a combined capacity of 98 litres.
The undercarriage is particularly noteworthy, as it is possible to convert the Raven from nosewheel to tailwheel configuration, or vice versa, in about two hours. Obviously you need two complete undercarriage sets (the main legs are of different length, so it’s not just a matter of substituting nose- or tailwheel). The test aircraft was configured as a taildragger and featured 21/8x6 tyres, with the steerable tailwheel suspended from a leaf spring arrangement.
Braking is provided by a pair of toe-operated hydraulic Matco disc brakes. A particularly interesting feature is that the braided stainless steel hydraulic brake lines are actually recessed into the trailing edges of the spring aluminium undercarriage legs. While it looks very neat I did wonder if this was ‘gilding the lily’ somewhat, and whether it was actually worth the effort.
Randy is confident it is, as it eliminates ugly clamps. He told me the company gets lots of compliments for the idea and it is beginning to show up on other aircraft, such as the Brazilian Paradise P1.
Access to the cockpit is via top-hinged doors on either side of the fuselage. These open a full ninety degrees, are fully supported by gas struts and are approved for flight up to 87 knots, although they must not be opened above 55. The door latches seem sturdy and well made and, although this may strike you as a minor detail, it’s been my experience that on some LSAs they can be more than a little flimsy − and just wait till a door opens unexpectedly in flight!
The rudder pedals are fixed but the comfortable seats adjust fore and aft on sloped rails, which raise the seats up as they’re slid frontwards. The seatbacks fold forward to provide access to the big baggage bay. This is made from a single sheet of aluminium, is a generous 0.6 cubic metres, can carry up to 36kg and is accessible in flight. I particularly liked the fact the baggage area does not have a cross-cabin steel brace (unlike the Super Cub), as this makes loading stuff into it a lot easier.
The cockpit is a good size and, unlike many other small two-seaters, we weren’t constantly rubbing shoulders as the bulged doors mean the cabin is 1.16m across at the widest point. Unsurprisingly, the panel is pure analogue VFR, which I liked. In exactly the same way ‘steam gauges’ simply look out of place in a modern turbine powered aircraft, a totally digital panel in a taildragging bushplane can look equally incongruous.
Nevertheless the Raven’s panel is not without its foibles, with two instrument anomalies being the curiously-oversized voltmeter and big OAT gauge. If the Raven was fitted with a 912iS and its associated EMU and dual ECUs I might be a little more concerned about what’s what with the watts, what? – but I can’t see why the test aircraft needed such a giant gauge. I also didn’t like how samey (in fact, identical) the controls for the choke, park brake and cabin heat are, and would rather the three-point harness had four-points. True, there are placards next to the plungers, but different colours and shapes wouldn’t go amiss.
Plus points were the simple sight gauges in the wingroots for fuel quantity, large skylight, bulged doors and toe brakes for both pilots. I approved of the white scale behind the sight gauges, which makes the fuel level a lot easier to see (some aircraft are terrible in this respect). Randy noted my quizzical expression about the rather curious multiple fittings and said that production aircraft will use a 90° fitting direct to the tubing.
In between the seats are the headset jack plug sockets, dual 12v power outlets and the flap lever. This has five positions; 0, 12, 25, 37 and 49 degrees. Pitch trim is electric only, controlled by buttons in the stick top with trim position shown by a strip of LEDs on the panel.
The throttle is a simple, centrally-located plunger, with the choke adjacent to it. There’s a combined rotary ignition switch for the mags and starter, with a small group of eight toggle switches and circuit breakers for the electrical services located directly below the flight instruments.
Curiously, one of these switches is labelled ‘carb heat’, as the carburettor is warmed by an electric heating element. In the centre of the panel is a Garmin Aera 560GPS, a GTX327 transponder and GTR200 transceiver. A neat feature of the GTR is that it incorporates the intercom.
Overall I was quite happy with the cockpit, but did think some shrouds and covers for the various exposed cables and pulleys were needed, while the exposed flap lever looked particularly vulnerable. Randy said this was already in hand (and to be fair, the test aircraft is s/n 001). Production aircraft feature a significantly revamped interior, including a cover over the flap lever mechanism and kick panels that hide the fuel lines and wires.
The Rotax bursts into life immediately the key is turned and I am soon taxying the Raven confidently towards the active runway. The field of view over and either side of the nose is excellent for a taildragger, rendering S-turning superfluous. The combination of a steerable tailwheel and powerful, progressive brakes provides positive steering. Even while simply taxying out, I sense the Raven seems somewhat less ‘squirrelly’ than say a classic Cub or Champ, and wonder if perhaps the C of G is closer to the mainwheels than it is on a Piper or Aeronca.
It’s a pretty cool day for Florida and as Sebring is only 10ft AMSL the ambient conditions are actually more favourable than ISA, while with full fuel and no baggage we’re still about 44kg below the Raven’s max AUW of 600kg.
As I always do for the first flight on type, particularly if it’s a taildragger, I bring the power up quite slowly, but there is no difficulty keeping straight, despite a gentle crosswind from port. The acceleration is excellent, and almost as soon as the airspeed comes alive we’re off the ground and despite opening the throttle slowly I doubt we used even a tenth of the 1600m available.
We climb away at 55kt and almost 1,000fpm, but this gives a slightly too high pitch angle for my taste, with so much show traffic buzzing around, so I soon lower the nose, gain another ten knots and trade the slightly reduced climb rate for a greatly improved field of view.
I always like to start an appraisal with some steep turns and reversals so I can get a basic feel for the control and stability, before moving onto stalls and slow flight. The roll rate in particular feels quite brisk (it’s quoted at eighty degrees/second) and while it’s no Extra, it’s pretty nimble for a bushplane.
What is interesting is how little adverse yaw there is and, while you do need a bit of rudder to keep the ball centred, it’s nothing compared to some aircraft. Some increasingly steep 360° turns confirm my initial impression of crisp, precise handling, good control harmonisation and low breakout forces, while the field of view all through the turn is fine, due mainly to the large skylight window set in the roof.
Stability around all three axes is good. Slowing down to explore the slow side of the speed envelope is interesting, primarily because the Raven just doesn’t want to stop flying. Indeed, with full flap (49°) set and some power it simply hangs in the air. RANS claim it stalls at 29kt, and I have no reason to dispute this − it is definitely very slow!
There is ample but not excessive pre-stall buffet as the wing approaches the critical alpha, and then tweaking the stick back just that little bit further makes the wing finally and reluctantly stall, although the Raven broke straight ahead with no tendency to drop a wing. The ailerons continue to work post-stall, although if you just ease off on the back pressure the wing starts flying again − and if you add power it’ll climb.
It’s a very docile, forgiving little aeroplane. From the slow-speed side of the envelope, I set the Raven up for a look at the cruise. At 5,000ft and 5,400rpm the TAS is just about 100kt, which is actually better than RANS claims, although we weren’t at MAUW. Fuel flow is in the region of 20lit/hr.
Back at Sebring, I continue to appreciate the fine field of view as there’s still lots of show traffic, and note that at 70kt the Vfe is higher than it is for many LSAs. A Vref of around 55kt seems about right, and the S-20 three-points nicely and rolls out with a minimum of fuss.
Directional control is good, courtesy of the powerful rudder and differential brakes, although it just isn’t as skittish as some taildraggers. Of course you could come in slower (the timehonoured formula of Vs1 x 1.3 gives a Vref of only 38kt) but I’d advise against that. It will only end in tears. If the strip is so short you need to come in that slow, do you really need to land there? On the plus side, as the takeoff ground roll is shorter than the landing run, I guess it would be impossible for anyone to land a Raven somewhere they couldn’t take off from, and there can’t be many light aircraft that statement holds true for!
The Raven is very much the type of aeroplane I’d like to own. It can carry an excellent load economically and at a good speed, fly both further and longer than either my bladder or buttocks can stand, and operate safely from really quite short strips.
It’s a very pleasant aircraft and a capable performer, but now we must turn our attention to the root of all evil; money.
The Raven is now available in the States as an S-LSA and the flyaway price is around $120,000. In many respects, the S-20 reminded me of the AC-11 Chief which, for those of you unfamiliar with Aeroncas, is also a high-wing, side-by-side, fabric covered taildragger, albeit one that hasn’t been produced since 1950. Nevertheless, even $60,000 would get you a pretty nice Chief or the licence-built Indian version, the HAL Pushpak.
So why buy a Raven? Well, it’s undeniable the Raven can fly both faster and slower, carry a greater load over a longer distance, land shorter and take off quicker. But that’s only part of the story. It’s a lot more comfortable, handles better and is simply a superior design, made with modern materials.
It is a much more economical machine, for if you pull the power back on a 912 the fuel flow reduces to less than 15lit/hr. That said, I would relish the opportunity to sample a Titan-engined Raven – with 180hp it must climb like a rocket!
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