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A low wing aircraft, a safe and easy one

by Franco Paolini

AMIGO ! and Savannah are the new 1997 models manufactured by ICP and are, respectively, the MXP-640 and MXP-740, duly revised and improved.
To both of the aircrafts the main modifications have been introduced to lower the weight, decrease the costs and increase safety by making the airplanes more controllable in the low and very low speeds range and by improving the flight controllability at all the typical speeds of operation.
By a first sight evaluation, the vertical tail surface new shape becomes evident. By telling the whole truth the MXP-740ís on display at Bassano had the fixed vertical fin, and the gained success, both in terms of flight quality improvement and appreciation by clients, convinced the ICP technical staff to modify the MXP-640 vertical empennage too: the modified aircraft has been displayed at Ozzano, last september, as a prototype.
Other modifications have been introduced on the wheels, now equipped with new line-sculptured tyres, specially oriented to grass airstrips, to the engine cooling system, now integrated with an effective cabin heating device, the new oil cooler, the new fuel supply system, now "vapour-lock" voiding proof even when using the most volatile gasoline, the new three positions height adjustable seats, the new forward-hinged cabin doors.
The Savannah model features now new cabin doors that can be opened by upwards rotation and a new wing-windshield fairing that is responsible for the further decreasing of the take-off and landing rolls, and the stall speed reduction. Following that brief foreword letís talk about the AMIGO ! model.
Why such a nickname while all the other aircrafts ones remind stars, skies, lightnings, foxes or numbers that recall mythical planes... On the beginning even I wasnít too much pleased of that nickname, but after some flight hours onboard this new aircraft model I was convinced the name has been a good choice since the plane appears as a docile and easy one, that promptly executes your control inputs without any particular tendency, that is a real friend whom itís a pleasure to fly with, at a high performance level and passing adventure over adventure, in an extremely SAFE condition.

The aircraft

It is completely built in aluminium alloy and the structure features load resistant skin panels; it is manufactured by using certified aviation materials only, for each component.
The wing features the usual NACA 65018 modified airfoil fitted with flaperons to increase the lift and drag in the low speeds range. The horizontal tailplane is of the symmetric biconvex traditional type. The tail vertical plane is classic, with a fixed part and a three hinges movable rudder.
The engine fairings, in fiberglass, is easily removable to carry out the pre-flight checks. The refuelling itís easy, since the wing fuel tanks are installed in a easily reachable position. The water cooler is located in a suitable locationin the lower part of the fuselage.
Ití easy to enter the cabin even if it could be improved by a step to climb the wing upper surface and, eventually, go inside the cockpit that, on the other hand, is very roomy (roomier of the SF-260 one).
The rudder pedals are not adjustable, while the seat height is adjustable and the particular piloting position which is imposed by the wing spar which passes just under the crew knees, is reachable by both tall and short pilots. The brakes controls are installed on the upper left hand pedals tips and, particularly the hydraulic brakes version features a very effective braking thatís variable with ease.
There are two control sticks fitted with an anatomic grip. Two are the power levers, the first on the left hand side of the instrument panel, the other in the middle of it, to ease the training operation in the various conditions and situations.
The electrical flaps are actuated by a lever-type switch located on the left hand side of the instrument panel. No flaps position lighted indication is provided, anyway the pilot can easily see the flaperons position at the left wing tip.
The longitudinal (pitch) trim tab control is an electrical type one, located on the left hand side of the instrument panel and is provided with a position indicator. In a slightly lower position the electrical Ivoprop propeller control lever is located (the propeller can be supplied as an optional equipment and itís very effective). On the central pedestal, located between the pilot and the passenger seats , is found the ailerons electrical trim control and all the other switches and replaceable thermal fuses which protect the other electrical devices : auxiliary fuel pump, strobe lights, navigation lights, landing lights, radio and internal communication device.
The avionic equipments are the ones needed to support the kind of flight that is possible and advisable to do. Tha baggage compartment which is located beyond the seats back, is very large and can be loaded up to a greater load than stated: it has to be checked the maximum weight and the aircraft center of gravity! The actual fly-away weight of the aircraft is not greater than 285 kg. Thus the aircraft can be considered an ULM from all the various point of view. Up to date there are 9 aircrafts which are flying in Italy and one in Spain : four out of them are powered by the ICP manufactured turbocharged 912 engine while the other ones feature the regular Rotax 912.

Operating test

Run-up the 912 engine, wait until the temperatures have reached the green arc, check the magneto RPM drop and the pre runway-alignment checks, itís the usual aeronautical procedure, a pleasant one.
The ground roll is easy and precise thanking the steerable forward wheel. Leaving the check point I align the aircraft to the runway and, after some more checks, set the flaps at 10į, propeller pitch at the minimum, then apply full power and the faithful 912 accelerate up to 5600 RPM.
The aircraft quickly increases its speed and, reaching 50 mph (about 80 km/h), by slightly pulling the control stick, the aircraft is airborne following a 100 meters ground roll.
I keep climbing at 70 mph (115 km/h) and 1100 ft/min., increase the propeller pitch to get a 5200 RPM engine speed and retract the flaps. Upon reaching a 1000 feet altitude, I level the aircraft, reduce power to 4800 RPM and cruise at 110 mph (180 km/h).
Iím impressed by the aircraft maneuverability around the roll axis : from -45į to +45į in three seconds and without any inverse yaw rotation. Sure, it isnít an aerobatic airplane performance, however in its category thatís a noticeable characteristic. By actuating the rudder pedals I obtain a prompt and authoritative response by the aircraft.
The new vertical tailplane, by comparison to the old one, brought a great improvement in a performance where the old 640 model and all the airplanes of the same origin were not so good : the directional controllability. Now a slight pressure on the pedal is sufficient to get the slip indicator centered at any time. It has to be noted a flight stabilising effect, due the new tail, which, on the older models was missing at all.
The visisbility, when airborne, is very good since the pilot is practically seated on the wing leading edge and the cockpit features large windows. I apply full power, i.e. 5,600 RPM to check the maximum speed and, with the aircraft levelled, I read 130 mph (220 km/h) .
In this condition the stick force varies a few only and a little trim action is sufficient to fly without apply any force on the control stick. At 5,000 RPM one can cruise at a 185 km/h true air speed with a fuel consumption equal to 15/16 liters per hour.
The serenity this aircraft brings to the pilot I believe is due to the great dihedral and the quite thick airfoil. I am able to say the induced roll by vertical axis control is almost equal to the one provided by tthe aileron deflection. In the low speeds range - 70/80 mph - the aircraft maintains a quick response to the vertical axis control and the aileron authority progressively decreases.
I set the engine to idel to check the stall, maintain the vertical speed at zero and can notice the first buffeting at 45 mph, while the full stall condition - full flaps - occurs under 40 mph (64 km/h).
The stall recovery is quick, it can be felt the airstream that join the wing skin again, eventually during the stall and recovery maneuver the aircraft go down a little more than 10 ft.
Thatís an exceptional performance! During the stall the aircraft keeps levelled, it doesnít roll, and the whole maneuver is a pleasant one. I want to check the aircraft performance while turning at a very low speed. So I climb to 1000 ft again, decrease power, maintain the aircraft in a 30į bank left turning, with a zero vertical speed, the speed decreases, 90...80...60...50... I can feel the first stall buffeting and the aircraft instead of increasing the turning ratio and putting itself in a spiral trajectory or a spin, goes back to a lateral levelled condition - on the horizon - and maintains a neutral attitude. Iím not so convinced, and try again the same maneuvers, more and more ... with the same effects.
At this point no more comments are needed : just in the most critical condition when the other aircrafts punish you for your lack of care or the excessive confidence AMIGO ! reveals its character that allows you to keep the aircraft back to normal flight attitude and go down avoiding any damage or danger.
In the low speeds range the aileron authority is good even if a slight inverse yaw occurs: that secondary effect can be quickly compensated by the very effective operation of the rudder.
In the "white arc" configuration, i.e. ranging from 80 to 40 mph and with the flaperons extended, the ailerons effectiveness decreases with the speed decreasing and the increase of the flaps deflection angle. In final with full flaps and at 60 mph the direction control is primarily kept by operating the pedals - rudder. Itís a normal condition when the flaperons are fully extended.
Good !!! Now I increase the speed to 115 mph again, choose a reference point on the ground, set the engine speed to 5200 RPM and check the aircraft performance by going into a series of lazy eights. AMIGO ! is a "super" one, precise in the various flight attitudes, the speed ranges from 60 to 130 mph then it can be concluded the aircraft is a "honest" one you can depend on. Ah ! I was going to forget an important thing : the VNE is set to 160 mph (265kmh).
At that point, flight test finished, written down some notes that will support me in filling out the flight test report, being airborne at an altitude of 1000 feet, I wish the check the aircraft behaviour during a simulated engine off emergency. So I set the engine idle, 70 mph, Iím over the airfield, shut down the engine.
I maintain the flight attitude, extend the flaps to a 10į deflection angle in order to gain a 600 ft/min descent rate at 70 mph and, by a 360į turn, enter the final leg. At 200 mt before the runway threshold I operate the flaps to the maximum extension and reach the short final at 60 mph. I carry out the normal flare touching down in ground effect at a speed slightly less than 40 mph, apply brake and, after a 80 meters ground roll stop the aircraft.
Conclusion : following more than 300 flight hours on this marvelous low wing flying machine, I believe its "honesty", docile way of flying and, overall active and passive safety, make it the ideal tool to be used by the flying schools. Itís easy to "learn" and to fly. For the touristic purposes I think no more comments can be needed: take a look at the report about the recent criusing throughout Europe ending beyond the English Channel.

Franco Paolini

mod.AMIGO !max speed VneKm/h 265 Manufacturer
wing designlow, cantilevercruise speedKm/h 190 I.C.P. S.r.l.
Via Torino, 12 - Piovŗ Massaia (At)
Tel. 0141/996305 - Fax 0141/996353
materialalluminium stall speed w. flaps Km/h 61
engineRotax 912stall speedKm/h 72
empty weightKg 285climb1100 ft/min
gross weightKg 556take-off rollmt. 70
heightcm 198landing rollmt. 100
wing spancm 800construction plans -
lenghtcm 600Price See homepage
wing areamq 12.5Importer-

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