Mag Article on the CTSW

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The CTSW is the original creation of scholars from the University of Frankfurt who designed the CT2K-version of the aeroplane as part of their aeronautical design study thesis. It first flew in 1985. It appears that the design languished for over ten years or so until spotted by German entrepreneur and aviation enthusiast, Matthias Betsch. In 1997, Betsch went into production and according to the company’s pamphlets, over 300 variants have been delivered to date.

 

The ‘SW’ version was introduced in 1999 and Flight Design claim some truly impressive numbers – the most notable being the aeroplane’s amazing range on a tankful of gas – indeed, one example has been flown between Germany and Greenland in a much celebrated flight last year. Germany has some pretty tight specification limits for this class of aircraft and the country is an expensive location in which to build. Betsch has managed to bring the cost down by shipping components to a Ukrainian factory, where the CT is built some 200kms northeast of Odessa and then shipped back to Germany ready for final assembly. Despite early reports of poor finishing, the aircraft I flew appeared to have most of these problems ironed out and Elmo’s demonstrator has obviously been completed to a high standard.

 

The airframe is vacuum moulded and is mostly carbon fibre rather than resin – indeed, Flight Design claim some notable safety features including a certification standard that allows the CT to be flown at up to 600kgs at gross weight. Moreover, the fuel tanks have been positioned in each wing and contain 130 litres giving a range of 1 100 nautical miles at a cruise speed of 130 knots. The cantilever wings make use of large flaps that spread across two thirds of the CT’s trailing edge. They are five position flaps, electrically driven, with a ‘minus-12-degrees’ facility for the cruise configuration.

 

The ‘moulded’ construction method has further provided another great benefit – a large baggage bay that almost takes up the entire rear fuselage area immediately behind the seats. Although it is not accessible in flight, the bay can be accessed by either of two hatches on each side of the fuselage and hey-ho … it’s big enough to hold a tent and a pair of camping chairs – and even a lightweight coolerbag plus soft luggage. Indeed the CT has an almost Tardis-like quality – looking deceptively small, the cabin is vast with plenty of headroom, legroom and shoulderoom that would almost put a Cessna 182 to shame.

 

An all-flying elevator provides pitch control with a cutout in the rudder to accommodate the flying surfaces’ upwards travel.

 

A fin extension has been added to the bottom of the fuselage boom for extra directional stability and to protect the tail in the event of a tailstrike. Whilst the interior may appear somewhat rudimentary at first glance, there are some clever additions – most notable are the small hinged panels beneath your legs.

 

These cover further stowage space and can easily take some cooldrinks, maps and other paraphernalia that occupants might require during a lengthy cross country trip. The seats seemed comfortable enough and all the controls fall easily to hand.

 

The most dominating structure is without doubt the sizeable instrument ‘binnacle’, which has a righthand side that is canted towards the pilot. Whilst the panel itself will most likely be completed to individual pilot’s tastes, there’s enough room for a full set of primary flight instruments. Whilst Flight Design provide a series of analogue gauges as standard, our demonstrator was fitted with an MGL Avionics Stratomaster electronic box giving a digital readout of all temperatures, pressures and other engine information including rpm. A centre pedestal contains the electrical switch panel and circuit breakers and a fuel shutoff lever that has to be in the open position before the engine can be started. The magneto switch is key activated just like your common or garden Cessna single.

 

At the pedestal’s base, four levers control trim, choke, throttle and brake. They fall easily to hand, though there might be risk of confusion despite Flight Design’s colour coded layout. The nearest to the pilot is the glider-type trim lever and next to that is the choke – only used when the Rotax engine is started from cold. Next is the throttle and beyond that the single brake lever. There are no toe brakes – a rarity in this type of ultralight – however, the CT’s system works well even though, to operate it, you are obliged to remove your hand from something else that is important. On the landing rollout or indeed during taxiing, I find it slightly disconcerting to take my hand away from the throttle. Behind the levers there is a parking brake and a welcome tray that will easily hold some pens or a packet of smokes – even an airfield guide.

 

Starting the 100hp Rotax is typically painless and the engine burst into life at the flick of the key. There is a fair amount of residual thrust from the brightly finished Neuform composite propeller so the efficient parking brake system is rather a neccessity. The CT gets underway by itself without really needing a burst of power. Immediately apparent is the lovely soft ride. Quite how Flight Design have achieved this is difficult to say.

 

However, the tubular undercarriage legs are attached to each other via a mid-fuselage inverted ‘U-shaped’ bracket rather than being merely fixed

 

to the external airframe with a supporting bracket.

 

I would imaging the setup would be ideal for rough strips. The nosewheel is often a weak link in this otherwise sturdy class of aeroplane and I was unable to take a close look at the firewall structure. However, steering was relatively light with good directional control through the rudder pedals.

 

With the pre-takeoff checks complete and carrying first stage flaps of 15-degrees, the CT accelerated briskly along Grand Central’s runway 17. The CT has relatively short wings – a mere span of 8.5 metres, so I wasn’t expecting any short field surprises. Moreover, the two of us, Elmo and I, weighed some 200kgs and we had about 80 litres of fuel aboard. It took about a quarter of FAGC’s runway to rotate on a pretty hot afternoon – a great deal more impressive than a Cessna 150 or even a 172. We climbed out at about 750-800 feet per minute at 70 mph. I also glanced over to the engine temperature readout as some of these Rotax installations weren’t optimised for the high ambient temperatures we get in South Africa. I was pleased to see that the temps and pressures were well within the normal operating range.

 

Once up to our cruise height of about 6 500 feet, the airspeed leapt as soon as we activated the ‘negative’ flap setting. There was almost no need to input trim as the aeroplane’s configuration and speed was adjusted but this is also typical of these types of aircraft. Control harmonisation is good with the rudder being somewhat heavier than the elevator and ailerons. Indeed there is little rudder feel so those not used to the CT will probably, like me, make continual reference to the turn and slip indicator to keep the ball centralised. Roll input was met by an instant response and the CT is immense fun to fly.

 

At our density altitude, the airspeed indicator quickly rose to 130 mph at 5 100rpm. I would suspect that the advertised 130 knots is not too far wrong, especially as I had noted the CT was difficult to catch up with in the Cessna 182 we had earlier used to carry out the air-to-air photography session. I tried a few steep turns and the aircraft felt solid and responsive, although an eye on the slip indicator was needed to keep the ball in the middle. Visibility over the nose isn’t too bad although the aircraft seems to fly nose-up – an optical illusion caused by the lowish seating position and large instrument housing. Upwards visibility is good for a high wing design. However, the big doors, almost entirely covered by perspex give the impression of great visibility – enhanced by the strutless wings. The roof contains perspex panels between the spar covering and help when making turns.

 

I put the aircraft through a couple of stalls – one without flap and one carrying a little power with full flap. The first configuration resulted in a very gentle roll off to the right at the break and the next a somewhat sharper roll off to the left. Both stalls were easy to recover from using power and relaxing back pressure on the stick. Overall, the CTSW handled very nicely indeed and it struck me that the aircraft would spring no nasty surprises in all phases of flight. Although the aircraft has been extensively spin tested, we didn’t explore that area of the flight envelope.

 

We returned to Grand Central’s circuit and giving the slippery little aeroplane plenty of room to slow down, I reduced speed to 70mph in order to deploy the flaps. 70mph is somewhat low for an aircraft with this level of performance, so entry into the circuit requires a little forward planning. Whilst its speed is easily sufficient for it to mix with far bigger aeroplanes, once settled into the approach at 60mph, the maximum flap speed means that during the final approach phases, there isn’t much speed to play with in a crowded circuit. Nevertheless, the aircraft is stable on final approach. Pilots might like to carry a smidgen of power into the flare as with full flap, there is a lot of stick travel to get the nose up to keep the nosewheel away from wheelbarrowing.

 

There’s plenty of elevator authority though and quite a sharp movement between the over-the-fence attitude and the landing attitude. In practice, this would be OK for getting in and out of shorter strips but for longer general aviation runways, only second stage flaps would be necessary to make the final touchdown less of a sudden manipulation of the stick.

 

The brakes are extremely powerful and wonderfully progressive. I suspect it would be possible to lock the wheels on touchdown. The only downside to this might be a tendency to easily lock the wheels whilst braking on a gravel or sand strip and thus flat spot the tyres. On a downhill slope whilst taxiing, I would be wary of cooking the tyres although, the discs seemed to be well ventilated.

 

I must admit to being impressed with the CT. I liked the roominess of the design and easy and safe flying qualities. My only real criticism is the high level of noise in the un-upholstered cabin – even with headsets, I suspect it would be tiresome on a long distance flight – consequently, most owners should shop for a pair of top-quality noise cancelling headsets if they plan to travel big distances.

 

The above courtesy of http://www.saflyermag.co.za/John%20tests/CTSW.html

 

 

[PaulN]

As a CT owner and regular flyer I have to endorse the above article (with a big smile on my face ... I love it).

 

However, I have to question the endurance stats quoted in the third paragraph. If my CT should be achieving 1100nm at a cruise of 130kn on a full tank of 130 litres (that's 15.3 l/h) I want someone to show me exactly how to tune the prop and a/c to make it happen. My max speed at full throttle (5340 rpm) is more like 128kn burning 24 l/h. That's more like an endurance of 690nm with, at the end of the flight, a red hot engine and a worn out crew from max noise.

 

I choose to cruise at a more realistic 100kn to 110kn (a touch more than quarter throttle) burning 12 - 13 l/h achieving a theoretical 1080nm endurance in a much quieter environment. But let's face it, theory and practise rarely concur, especially in our aerial environment of changing densities and winds.

 

For anyone considering the purchase of a CT my recommendation is to not spend too much time pondering these sort of specs, just get on the phone and place your order. The sooner you have your new CT proudly on display at your chosen airfield andyou get up there enjoying its many delights, the sooner you'll know you made a good choice. From personal experience I have to say it's a great little plane.

 

PaulN