Airtest- Siai Marchetti SF.260

The SF. 260 was first certificated in April 1966 as a military trainer and since that time, 27 airforces have purchased in excess of 1,000 aircraft. In addition more than 100 civilian versions are in operation around the world, most of which are in the US.

As can be seen by the accompanying photographs, it is a low wing, tricycle retract undercarriage, piston engine aircraft with very distinctive tip tanks a Ja the Macchi. It is powered by a 260hp six cylinder Lycoming 0540-E4-A5 driving a constant speed airscrew. Although a four seater, it is more akin to theJaguar E Type ”two plus two”, with not much room in the rear seats.

Accompanying Noel Kruse as he did the preflight, it was immediately apparent that this was an aircraft put together by craftsmen. The panel fit was first class as was the overall finish. The deep red colour added to the expensive Italian sports car effect.

On strapping into the left hand seat, which was upholstered in the fashion of early model Jaguars, the instrument panel immediately dated the aircraft with its older style instruments. This in itself is no bad thing as you can at least read the dials. Instead of a separate fuse panel, fuses are located with tl1eir particular gauge, this has its merits particularly in the case of the undercarriage and flaps. There is a central engine management panel, ie throttle, pitch and mixture with the throttle, which is the push in type, having a very large vernier wheel for adjustment. I found this latter arrangement quite good for throttle control, even in the circuit.

Unfortunately the canopy on this particular model cannot be opened in flight but it is certainly an advantage to be able to open it on the ground as an aid to cooling.

Fuel is carried in wing tanks (98 litres) and of course in the tip tanks (140 litres) which must be empty for aerobatics and was the configuration for my flight. For general upper airwork a fuel consumption figure of 60 litres an hour is used; cruise at 150kts is planned at 55 litres an hour. With full fuel, three hours ‘safe’ can be expected giving a range of 580nm.

It was good to have a control column again although it is a little on the tall side but obviously necessary to provide leverage in roll. This was confirmed in flight as the ailerons are quite heayy, stiffening up with speed. Noel mentioned that he has the aileron servo modification on his wishlist for updating the aircraft. Coincidently, the list also includes a complete revamp of the cockpit layout, moving the flight instruments to the right hand side for the aircraft to be flown from the right hand seat (left hand throttle, right hand stick), this is the configuration of the military trainer. GPS and an autopilot would complete the dream. However the cost evidently doesn’t bear thinking about so it will remain a wishlist for the time being. The motor was certainly smooth after sitting behind a four; however I was surprised to discover that it has a normally aspirated carburettor rather than fuel injection. The latter is evidently an option but unfortunately was not installed in this particular aircraft at manufacture. The lack of fuel injection limits negative “g” to about one second; as I was to discover later. There is also no inverted oil provision, which will cause the prop to go into full fine if the aircraft is held on its back for too long.

Once we lined up and were finally cleared to go, I was most impressed by the acceleration down the strip. Takeoffis made with 10 degrees of flap and climbing speed is a comfortable 108kts. It was immediately apparent on climb out that the aircraft has a high-performance wing, we didn’t suffer the usual bouncing around in turbulence which is the lot of the average “lightie”; we sliced straight through it with that cobble stones effect you get in a jet.

The initial part of the sortie was a photographic session with one of the Schools Robin 2160’s and when that was completed Noel handed over to me to play round as I wished. I had flown the aircraft on the way out to the training area noting a slight tendency to snake, and the fact that the ailerons certainly weren’t light.

After the usual couple of steep turns with reversals to get the feel, I tried a few barrel rolls. Rolling manoeuvres require 140 -150kts and the bird goes round with ease, surprisingly the relatively heavy ailerons didn’t seem to present a problem. I naturally flew the aircraft with my right hand and was amused at myself groping up in the left hand side of the cockpit for a throttle; old habits die hard!

Next I flew a couple of loops which require 170kts and the usual 4g, easing offover the top and pulling again on recovery; again no problems. I tried a level aileron roll and despite being cautioned about negative “g”, instinctively tweaked forward on the stick when we were on our back only to get an immediate unhappy response from the prop. As soon as positive “g” was restored, things returned to normal.

Noel had previously said that the aircraft is tame in the stall and this was confirmed in both high speed and one “g”stalls where control remained good right to the ragged edge.

It was possible to pull the aircraft into the stall from a steep turn and to have it sit there with the wing burbling away, showing no signs of wanting to flick. It reminded me very much of the Vampire trainer which would just nod its nose as you pulled it into a high speed stall, continuing with the turn as you relaxed the back pressure.

The lg stall was made at idle and occurred at 65kts as advertised with aileron control still available (not that any self respecting pilot would use it to pick up a wing!). I had noticed on the preflight walk round that there were wedges on the inboard leading edge to ensure root stall before tip stall, and that there were winglets on the tip tanks which obviously smoothed the airflow over the aileron at high angles of attack.

Noel then took over to demonstrate the finer points of its aerobatic capability running me through part of the routine he had developed for displays. This included a vertical climb to a 90 degree roll followed by a stall turn with a quarter roll back down onto the original line.

The stall. turn was executed at about 40kts, any higher speed and the aircraft will tend to park itself in a nose high attitude and not complete the tum due to the relatively small rudder. Providing zero angle of attack is maintained, its are impeccable with no tendency to flick; however 1t flicks on demand with precision.

On completion of the upper airwork we returned to Bankstown for the obligatory touch and goes where once agarn the handling proved to be precise and predictable; however the little wing requires accurate flying.

From a fighter break we were downwind with the tiptank running down the runway. 20” and 2,500rpm are the downwind numbers. Once the speed is below 130kts, 10 degrees of flap is selected followed by the gear below 108kts to stabilise at 100kts for the turn onto base. 30 degrees of flap and 90kts on finals with the speed tapering as full flap is lowered, and shortly after winding off throttle for a full flare. 10 degrees of flap is maintained on a touch and go to avoid wheel harrowing which it is prone to if the attitude is kept too flat.

After Noel’s demonstration circuit I was allowed to fly a couple and found it just as pleasant as in upper air work A slight crosswind was handled without too much difficulty. On the full stop, aerodynamic braking slowed us down and as directed, I was careful to keep the weight off the nosewheel to prevent shimmy.

I’ve always found the most difficult part about flying a new aircraft is getting used to the brakes! The SF. 260 is no different and I was just about coming to terms with them by the time we got back to the flightline. Shutdown was routine with everything off.

From my brief flight in the aircraft, I readily reached the conclusion that the SF. 260 is a splendid aircraft and a joy to fly; you would never be bored if you owned one. In addition, just as a vintage sports car provides its owner with pleasure from the admiring glances it receives, so too does this aircraft delight the eye with the perfection of its lines.

Our thanks to Noel Kruse and the Sydney Aerobatic School