Aircraft Reviews

>> THE RAVIN 500 BY SCULLY LEVIN
>> THE RAVIN 500 Trevor Merton, Vice President, Precision Aero Engineering, LLC

Flying the Ravin 500 South Africa is a land that often surprises with the world-beaters that it produces. From its loins have come famous golfers, tennis players, sprinters, medium and long distance runners, swimmers, actors, authors, musicians, businessmen and entrepreneurs. Talent in one field after another abounds in this beautiful country, and often from the most unlikely of sources.

Add to the above list "aircraft designers and manufacturers", for out of a garage in a homestead North of Wonderboom Airport, has come one of the most exciting and lovely aircraft I have ever flown, a Comanche look-alike, simply called, the "Ravin". This aircraft is the brainchild of one Jan Troskie, a long time Comanche owner, who figured that he was going to take a great design and a great aircraft and make it even better. This he did, in under two and a half years, with no fuss, no fan-fare and no razz-a-ma-tazz. Combining huge latent talent with enthusiasm, passion for the Piper Comanche, commonsense and liberal doses of "Boere manier" know-how, he has produced a truly phenomenal aircraft.

Sunday 6th April, 2003 was certainly a red letter day for me, for on this day Dirk de Vos of Wonderboom Airport organized an invitation from Jan to fly the Ravin. Dirk is another pilot that has a passion for Comanches, and having been one of the first to fly the Ravin, he called me to say that I just had to fly this machine. There was a double bonus associated with the invitation, as Jeremy Woods, a long time friend, said that he would fly me back to Rand Airport in his 1959 Comanche 250, the very same aircraft that I had owned and then co-owned over a period of 16 years.

I would thus have the opportunity of comparing the new with the old on the very same morning……

Standing in isolation, one would be excused for mistaking the Ravin with a late model Comanche. The two aircraft look almost identical However, the original machine is of all metallic construction, whereas the Ravin is all-composite. Closer inspection of the aircraft reveals that there is not a single rivet on the airframe and that the entire machine is as clean as a whistle. Jan tells everyone with great pride that the total number of composite parts in the entire airframe amounts to only one hundred and fifty. This is as opposed to the many thousands of parts in the original Comanche, where screw heads and rivets stand proud all over the airframe.

Nor is there an antenna to be found anywhere on the aircraft. These are moulded into the airframe during construction so that they will not produce any drag.

The aircraft is powered by a stock-standard 260 h.p.Lycoming IO 540 engine driving a three bladed Hartzell propeller. Great attention has been paid to the placement and design of the engine's air intake so that the propeller, which has extensions added to the trailing
edge of each blade, is able to transmit pulses of higher pressure air directly into it. By so
doing the manifold pressure is raised by up to 1.5 inches Hg in cruise flight, thus further enhancing the performance of the aircraft.

The all-composite wing is immensely strong, being good for well over 5 "g". This was constructed by Francois Jordaan, who is rapidly developing an excellent reputation for the composite wings he has built for many other aircraft.

The Ravin is in fact slightly smaller that the Comanche all-round. The entire aircraft has been scaled down some 6% to 7%, but the cabin is still roomy enough to be very comfortable. There is more than enough shoulder room for two medium to large sized men in the front, and the two back seats certainly look comfortable and roomy enough.

There are other differences that become immediately obvious as one prepares to fly the aircraft. Entrance to the cabin is via a smallish door on the left hand side of the aircraft adjacent to the pilot's seat. Jan works on the principle that the pilot should be "last in, first out". There is no catwalk material, as this would produce some drag, however small. Once everyone is seated, the pilot being last, the cockpit door is pulled down and into position and then firmly latched into position.

The windows are made of thick plexiglass and are also moulded into the structure, thereby contributing to the overall strength of the entire machine. The prototype Ravin has no interior upholstery, and yet the cabin does not look Spartan at all. The composite material had its own colour-speckled pattern built into it and this certainly does not look unattractive. The floor carpeting and four luxuriously covered and comfortable leather seats give the cabin an air of simple and unaffected functionality. The second aircraft and third aircraft, which are already in the advanced production stage, will both have fully upholstered interiors.

The instrument panel has been laid out very neatly indeed and is more than adequate for any use that the aircraft may be put to. The radio's in this, the prototype, were mixed and varied, but the entire avionics package can be fitted to order and depends on what the purchaser ultimately requires.

Jan accompanied me on my first flight in the Ravin and simply let me get on with the job with operating the machine. He merely stated that if I had flown the Comanche before, then there was nothing that he could really add. The start up and taxi out was entirely conventional although it felt that one was slightly closer to the ground. The steering was positive and the breaking was good.

It was on the take-off that the first manifestation of what was to come presented itself. The aircraft fairly leapt forward out of the starting blocks as the throttle was advanced

and tore down the runway with a huge sense of urgency. We were airborne and climbing away in no time at all.

In spite of the lack of interior upholstery, the noise level with headsets on was not really high and we were able to converse with ease through the intercom. A few gentle
manoeuvres followed, an I do believe that within the first two or three minutes of being airborne, I turned to Jan and said "This aircraft is a masterpiece!"

This is indeed so, for the aircraft combines huge speed and performance with delightful handling characteristics. The aircraft feels very stable throughout its speed regime. The controls are light and extremely responsive…….. but more about this later!

Having spent some twenty minutes in Pretoria's general flying area, we cruised back to Wonderboom at 195 m.p.h indicated in straight and level flight and then joined the circuit for the landing. The approach and landing was entirely straight forward and not unlike the same exercise in a conventional Comanche.

A second flight followed in which Jeremy Woods, was given the opportunity to savour the delights of this new machine. After our return we thanked Jan and Dirk, and then flew back to Rand in Jeremy's 1959 Comanche 250, also a great performer, but at a cruising speed some 40 m.p.h. slower than the Ravin's.

I could ramble on and on about the aircraft's handling characteristics and its features …..
the trimmers, flaps, operation of the undercarriage, stalling characteristics, ventilation, noise levels, visibility from the cockpit ets, etc.. This is all stuff that would bore the reader and that the aspirant purchaser would find out for himself in any event.

For me, the greatest excitement associated with the flying of this aircraft came when Jan asked me to demonstrate the aircraft at the Ermelo, EAA and Rand Airshows. Given the incredible strength of the aircraft, its control responsiveness and its performance, and also the fact that the machine is an experimental prototype, permission was obtained to perform rolling manoeuvres with the machine at these airshows.

Suffice it to say that this aircraft proved to be a sheer delight to demonstrate. There was a huge surfeit of performance through one wingover after another, and at no stage did the aircraft ever become energy deficient. The aircraft showed off its capability in the rolling plane by flying fast, super-slow and hesitation rolls. All of this in a four-seater cabin class machine!

Since the aircraft has not been spin tested yet, no pitching manoeuvres such as loops and stall turns have been approved. Not would Jan in fact want anyone flying any such manoeuvres. He stresses that the aircraft has not been designed as an aerobatic aircraft and does not want any buyer of the machine going out and doing aerobatics in it. He requested permission for the limited aerobatic manoeuvres to be flown in order to demonstrate the aircraft's strength and agility.

The Ravin is simply and undoubtedly the most exciting and exhilarating cabin class aircraft I have ever flown. It combines grace, beauty, exceptional handling qualities and unusually high cruising speeds with good load carrying capability over long distances. The original Comanches were hard to beat in all of these categories, those being the qualities that endeared the aircraft to me in the first place. However, the Ravin 500 goes many steps better and makes a "great aircraft, even greater"!

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THE RAVIN 500 Trevor Merton, Vice President, Precision Aero Engineering, LLC

As a teenager learning to fly in the '60s I at last had opportunities for hands-on experience in several of the aircraft that had long captured my fevered imagination. My initiation into the mystery of aviation and the magic of aeroplanes was parallelled by my early experiences with the fair sex. At Saturday night dances I soon learned that the sleek, sexy appearance of the young ladies that I fancied gave no clue about their abilities on the dance floor. Alas, many of those great-looking girls lacked grace in movement and a sense of rhythm and timing. My anticipated dancing pleasure was too often transformed into a humdrum callisthenics exercise set to music.

So it was with Mr. Piper's PA24 Comanche. Several Comanches were based at my local airport in the '60s and I had watched their comings and goings with intense interest. Surely such a fast, fine-looking, fire-breathing steed would repay its pilot with excitement and pleasure galore! Sadly, it was not to be. While the Comanche is an efficient aircraft and economical to operate, knowledgeable, widely-experienced pilots do not regard it as a paragon of handling pleasure. The Comanche's fine performance is not equalled by its control harmony and handling qualities. Pilots hoping for a dancing session with a tango expert will have to settle for a shuffle with an aunt at the local barn dance. Don't get me wrong; the Comanche meets all of the FAA Part 23 criteria that ensure that the aircraft is safe to fly in Normal Category. It's just that I feel it's rather stodgy in manoeuvre and suffers from mediocre control harmonisation; an opinion generated through several hundred hours of Comanche flying in the 180HP, 250HP, and 400HP models in the '60s and a few more hours in a 260C in the '90s. In comparison with over 50 other types of aircraft that I have flown from single-engine biplanes through piston and jet fighters to four-engine jet transports, the Comanche is ranked low on my flying pleasure totem pole.

On a recent visit to Wonderboom airport near Pretoria, South Africa, I was shown a truly modern version of the venerable Comanche. Constructed in epoxy resin/glass fibre/carbon fibre composite material the look-alike Comanche is around 94% of the Comanche's size and proudly wears the name 'Ravin 500'. I was immediately struck by an impression of sleek beauty and gem-quality perfect, mirror-smooth finish. A curvaceous Hartzell scimitar propeller and a nose cowl featuring a flush NACA air intake duct in place of the external scoop worn by early model Comanches enhanced the flowing lines of the Ravin. You can appreciate though, that my admiration of this bird was tempered by my memories of Comanches. Would the promise of this gorgeous appearance lead to another humdrum flight experience? I wasn't exactly aching to find out and was prepared to move on after a brief, distant glance.

My companion was more than impressed by the Ravin's beauty and insisted on a closer inspection. As we walked around her it soon became apparent that the Ravin differs from the Comanche in a number of significant ways. The aerofoil is based on the original, familiar NACA 64-series section but features modern Harry Riblett enhancements for improved efficiency through a wider range of the flight envelope. Drag-reducing tips also add a modern touch to the wing. In place of the familiar Piper horizontal, all-moving "stabilator" the Ravin features a conventional arrangement of fixed horizontal tailplane and hinged elevator. The ailerons have an approximate 2:1 differential action and are remarkable for the perfection of fit between the ailerons and the wing trailing edge. Less obvious is the slight Frise projection on the lower leading edge of each aileron. This becomes visible below the wing when the aileron trailing edge is deflected upwards.

My interest in the Ravin having been considerably raised, I was pleased to be introduced to her creator, Jan Troskie. A long time Comanche owner and enthusiast, Jan believed that the basic Comanche design had many virtues and deserved preservation in a rejuvenated form. Having previous experience of composite aircraft construction he was undaunted by the prospect of constructing the Ravin from scratch.

With Jan as my guide, I inspected the Ravin workshop and was struck by the obvious professionalism exhibited in all aspects of the aircraft's construction. The Ravin team possesses impressive engineering credentials and the Ravin crystallises their combined experience in a very emphatic manner. I quizzed Jan with some of my favourite awkward questions about design and construction issues and he fired answers back to me in a forthright manner that spoke volumes about his knowledge, ability, enthusiasm, dedication and commitment. I was shown samples of spar sections and landing gear components that were fabricated and tested in-house. The workmanship, fit and finish were first class and the test results indicated that all components substantially exceeded their design specification. When Jan invited me to fly the Ravin I accepted without reservation and with a much-heightened sense of anticipation.

Back at the airport, I was introduced to local pilot Lourens Kotze' who filled in lots of gaps in my knowledge of the Ravin and patiently assisted me to explore her flight characteristics.

The Ravin 500 employs a retractable landing gear that utilises similar components to the original Comanche but the operating system has been improved to ensure that the alternate landing gear extension system is easier for the pilot to operate than the original. Unlike the Comanche, if the landing gear is manually extended it's not necessary for a subsequent workshop visit to reset the landing gear for electrical operation. The gear is mounted on a steel torsion-resistant framework that also serves to stiffen the wing spars.

In place of the forward-opening door on the right hand side of the Comanche, an upward-opening gull wing door is fitted on the left side next to the pilot's seat of the Ravin. I was initially dubious about this arrangement but found that access to the aircraft was readily accomplished by sitting on the front of the wing then swinging one's legs into the cockpit. It was surprisingly easy, offering easier ingress and egress than many low-slung sports cars. Ladies need not fear ungraceful entry and exit with this bird. The Ravin is fitted with four seats and there is a considerable volume behind the seats for baggage, golf clubs and the usual bric-a-brac hauled around in light touring aircraft. As with the main cabin door, the baggage door opens upwards from top hinges.

The cabin of the prototype Ravin is nicely furnished with four comfortable seats but otherwise looks a little Spartan. I was concerned that there wasn't much in the way of sound insulation and thought that the interior noise level would be high. My fears proved groundless, however, and in-flight conversation proved easy via the intercom system set to fairly low volume. The cabin size does not suffer in comparison to the Comanche, no doubt because the composite construction does not need internal framing like the original metal aircraft. The comfort level for four full-size adults is very good.

Cockpit layout is conventional with the prototype sporting a full array of IFR instrumentation plus a nav-comm stack featuring a moving map GPS. Another appealing feature was an integrated electronic engine display. The engine controls are levers mounted on a centre quadrant at the lower line of the instrument panel. I much prefer this arrangement to the Comanche layout, especially as the levers fell naturally to hand for pilots in both front seats.

The 260-HP Lycoming IO-540 engine nestling comfortably under the shark-nose cowling is the same powerplant seen in the Comanche 260C. Feeding the very modest thirst of this well-respected powerplant are leading edge fuel tanks with the amazing capacity of 160 US gallons. At a typical cruise power setting of 65%, this provides flight endurance in excess of eleven hours! The tanks are baffled to inhibit slosh and also fitted with non-return valves to prevent unwanted fuel transference between the wings.

Flying the Ravin 500 was a memorable, revelatory experience. Wonderboom airport elevation is 4100 feet and the temperature was 250C giving a density altitude of approximately 6000 feet at the prevailing barometric pressure. A crosswind of about 6 knots was blowing across the runway. There were three adults on board, including yours truly, miscellaneous kit and cameras and enough oil and fuel to fly across half of Africa.

Taxying the Ravin was utterly conventional with tight turns easily accomplished. Takeoff was initiated by fully opening the quadrant-mounted centre throttle whereupon the Ravin responded with Comanche-like acceleration. Reaching liftoff speed I gingerly raised the nose a little and waited for the Ravin to fly off. After gear retraction, the aircraft was accelerated to 130 kts IAS for a cruise climb. Setting up 22.5 inches MAP and 2450RPM, the rate of climb was checked by altimeter and stopwatch and found to be around 800 feet per minute at about 7500 feet density altitude. Very impressive. Under direction from Loureus, I set out for the local training area and performed a standard series of handling and performance checks learned at test pilot school.

As the checks progressed it dawned on me that flying the Ravin was great fun. It was difficult for me to maintain my professional, reserved demeanour and not grin like a fool. Because the Ravin wasn't fitted with specialist flight test equipment my assessment was somewhat subjective. It was fairly obvious, however, that the Ravin easily met the FAA requirements for flying qualities and performance characteristics. Nowhere in the FAA Regulations does it say that an aircraft must delight its pilot so there is no such box to tick on my flight test report page; so I wrote in longhand "Sheer delight!" The Ravin's controls are light to manipulate, stability is good around all three axes and importantly for enthusiast aviators, control harmony is superb. The accepted ideal control force ratio is expressed as A1:E2:R4 [for aileron, elevator, rudder] and the Ravin closely adheres to this standard. There aren't many aircraft that seemingly respond to the pilot's thoughts without conscious muscle inputs but the Ravin does. The ailerons are especially light to manipulate, thanks to their differential action and Frise-type projections.

As far as its performance goes, it's hard to comprehend just how far the Ravin is ahead of standard Comanches. We had spent most of our flight at mid-range speeds while conducting handling and stability checks. As we turned back towards Wonderboom airport, power was again set to 75% in level flight at a density altitude around 7000 feet. Although we were bumping along in light turbulence, the airspeed settled within a minute and a computer check revealed the astonishing true airspeed of 195 knots! The 400-HP Comanche was hard pressed to reach that kind of speed as I recall. Consider that the Ravin can turn out this sparkling performance while virtually doubling the Comanche's range and it will be obvious that this is a remarkably capable aircraft. When one considers that the Ravin is more than twice as structurally strong as the Comanche, the realisation of the magnitude of the Ravin team's accomplishments is truly awesome.

Turning onto final approach and fully extending the wing flaps, indicated airspeed was reduced to 75-80 knots. Memories of the Comanche flooded back. I recalled "notchy" stabilator response during landing flares and little ability to prevent the nosewheel thudding down shortly after main gear touchdown. Flaring for landing, I held the Ravin about a foot above the runway until it stopped flying and settled lightly to earth. It was easy to hold the nose up for a considerable period after touchdown, and then gently ground the nosewheel. That's a considerable improvement on the Comanche.

It was a very enjoyable experience to fly the Ravin. Such a mix of high performance and high pleasure is rare in a light aircraft and I told Jan Troskie that it had been a privilege to fly his creation. He smiled, knowing that I would say that very thing, as had all the Ravin's previous pilots.

Leaving Jan's workshop, I mused that I had virtually taken the Belle of the Ball to a dance, and what a dancer she was! She had given me indelible happy memories of the occasion. I had learned something too of her Olympian qualities (Marathon runner and sprinter!) and am eagerly anticipating our next date.

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