Frati and Nustrini
by Alfred Scott
This appeared in the September 1982 Falco Builders Letter.
Note. At this time, the Falco Builders Letter did not have 'articles', but rather was a long rambling narrative by me. I had just taken a trip to Italy where I met Stelio Frati and Luciano Nustrini for the first time, and Falco builders were dying to hear about Frati and Nustrini -- whose Falco is the stuff of legend thanks to the incredible speeds he had reported. So the following is simply part of the builder letter, and this is where we come in.
Renato Cairo, Stelio Frati and Alfred Scott in Mr. Frati's office
Later that week, I flew to Milan and was met at the airport by Mr. Frati. Unfortunately, he speaks relatively little English, I speak absolutely no Italian, so we were able to talk only through others. Fortunately, Mrs. Bielli, Conrad Lozinski and Renato Cairo of General Avia were able to translate back and forth.
General Avia is located in an industrial district and is housed in two large adjoining shops with offices in the front. In one shop they were building the second and third prototype Canguro for SIAI Marchetti. A number of little changes have been made and the draftsmen are working on the final production drawings. A Pegaso sat in the front of the shop. Pegaso, Canguro and SF.260 components were to be found stacked around the shops. In the other shop there was a nearly completed Condor, which is a version of the Pegaso that Mr. Frati is now designing. The aircraft has a bubble canopy, twin Allison turboprops, a longer tail cone and two hardpoints on each wing. The canopy arrived as I was there and was fitted to the aircraft. The Condor was undergoing landing gear cycle tests.
Stelio Frati's 1943 design study.
There are about 20 people working at General Avia, and a stray cat has taken up residence in Mr. Frati's office, and she spends most of the time sleeping on his desk or walking disdainfully over the aircraft drawings. Around the office were to be found drawings, photographs and models of Mr. Frati's many designs, and there were a lot of other aircraft designs that never came to fruition. There was a model of a twin engine bomber (which bore an exceptional resemblance to the Mosquito but with tandem seating) which Mr. Frati designed in 1943 for his engineering degree. Another early design was a high-wing radial engine transport with two Fiat Topolinos shown as cargo. There was also a business jet, somewhat resembling the Jet Commander. Latest on the drawing board is a tandem seat military trainer with a Lycoming piston engine. There were also a lot of other design studies of various light planes. The whole operation is really very remarkable, particularly when you consider how tough the aircraft business is. It is also interesting to focus on what they have to work with. It is very hard to get things shipped to Italy, and the government ties things up forever. With the exception of a few things like cabin air vents which they buy from Fiat, they make everything that is not carried in the Van Dusen catalogue. Specialty items which we can easily get with one telephone call here after a search for the manufacturer are all items which they make. Gears, bushings, shoulder screws, pulleys, universal joints, knobs and door handles are just a few items I saw that they made themselves. The simple fact is that Mr. Frati can have the part made in their shop quicker than they can find the part by calling to the U.S. or Europe.
Conrad Lozinski and the bomber design.
I suppose you would like to know something about what Mr. Frati is like. He is a very nice and unfailingly polite man. His aircraft design work is his life. He is single, and he is more likely to be found at his office on a Saturday or Sunday as anywhere else. He is obviously very intelligent -- Luciano Nustrini later told me that he considered Mr. Frati a true genius. You must remember that Mr. Frati was once a professor, and although he hasn't taught for years, the professorial manner endures. The office, the drafting room and the shop continue to be something of a school, with the employees as much students as workers. A question is raised, and Mr. Frati answers with a small lecture. It is clear that everyone understands the point, but the lecture continues to its conclusion. I left thinking of how I would answer people who asked me about Mr. Frati, and I came to the conclusion that the best answer would be to say nothing and to let his work speak for him. On my return home, I read again James Gilbert's piece on Mr. Frati, and I would not change a thing. I can only add that those of you who are building the Falco know him better than you think.
Alfred Scott and Stelio Frati.
I went to Florence by train to visit Luciano Nustrini. We spent the afternoon at the airport going over his Falco, and later we went for a ride. I went to Europe with two nagging worries. One was that all Falcos were heavier than the weights we have listed in the specifications. My Falco, remember, is about 100 pounds more than it should be, and Peter Hunter's Falco is also heavy. In Milan, Mr. Frati produced the figures of the official weighing of the Falcos for original certification. Typical equipped weights were 1,186 lbs. with fixed pitch propellers and 1,223 lbs. with constant speed propellers. Nustrini's Falco now weighs 1,129 lbs. with constant speed prop and 160 hp engine, although when he first bought it, it was stripped of the electrical system for racing and weighed only 1,025 lbs. Larry Wohler's Falco also came in at a good light weight.
The other nagging worry was that Nustrini's Falco was not as fast as reported. He had earlier reported that he had been timed at 228 mph and later had won a race at 234 mph. The speed is so incredibly high that I would never believe it if I had not also seen it published in a magazine with the official results. I was still bothered by the formulas also given (it was all in Italian), and I kept wondering if it was an adjusted speed, or something. Nustrini's Falco does not have a top speed of 234 mph. I'll get to this in detail later on.
Nustrini's famous Falco.
I made 10 pages of notes on my trip to Europe. Most of it is on Nustrini's airplane. His Falco is a Series I Falco which was originally built with the 135 hp engine. The tail surfaces of all of the Series I Falcos are slightly smaller than those of the rest. Nustrini's Falco was actually the second Falco built, and there are a number of things about the airplane that are quite unlike the later Falcos. Nustrini has also made a lot of changes to the airplane. The canopy is the most obvious change, but there is almost nothing that has not been done for increased speed. The jack pads are recessed into the wing (I don't know how this was done), and nice fairings have been installed on all of the hinges. The aileron and flaps did not have fairings on the top (except at the aileron pushrod), and there was no opening. It turns out that the upper leading edge skin of the ailerons and flaps were extended over the hinge to form something of an overhang. From above, there was no hinge opening at all. The ailerons and flaps are reflexed, with the trailing edge of the aileron up 12mm at the tip and the flap up 15mm at the root. This required that the lower leading edges of the flap and aileron be re-built for a smooth contour. Nustrini says that his Falco is optimized for maximum speed at sea level, and that this change hurts his cruising speed at altitude. Also, it increases his landing speed due to the loss of lift on the outer panels. He has also installed aileron and flap gap seals (mylar glued to the wing and leading edge of the surface in the shape of an "S") which helps with speed but really hurts the effectiveness of the flaps. The stall strips on the wing are gone, so he has no stall warning. Also, Nustrini has moved the battery to the engine compartment for rather technical reasons. (In normal cruise, the Falco has slightly down-elevator, and by moving the battery forward, the elevator goes to a zero angle of deflection.) The result is that Nustrini's Falco is very nose-heavy, has no stall warning, lands about 15 mph faster than normal Falcos, and my impression was that it lacked the elevator effectiveness to do a full landing flare in ground effect. It was quite a different airplane to land, and I came away with the clear impression that it would be very dangerous in the hands of anyone not well checked out in the airplane. I have over 100 hours in my Falco now, but if I had been turned loose in that airplane without a complete briefing or check ride, I would have crashed it on my first landing.
I had earlier reported that Nustrini had wing tanks like the Series II Falcos. This is not so. He has fuselage tanks like normal Falcos, and the aft tank is filled through an access panel in the canopy skirt fairing. The tanks are vented through the cap (which by virtue of being inside the skirt fairing is also within the cockpit) so the cockpit has a continuous scent of gasoline. Since the aircraft is quite nose-heavy, Nustrini can load more weight in the back of the plane. In addition to his normal aft tank, he also has a larger aft tank of 30.3 gallons (the front holds 18.5) which he uses for longer trips. He also showed me a luggage compartment ferry tank of 52.8 gallons. His range with all this would be about 3000 sm, but Nustrini readily admits that this is all fantasy, and he only uses the tank to bring fuel into Italy and escape local fuel taxes.
Nustrini's Falco was stripped to bare wood and covered with micro-balloons/epoxy and sanded smooth and painted with a polyurethane enamel. The paint is five years old, and with the exception of some flaking around the firewall, the paint looked new. With the exception of the area just aft of the firewall, there is no fabric on the airplane. There are no drain holes on the bottom of the fuselage, wing or tail group. You may remember that there was a flood in Florence in 1966. Nustrini's Falco (and two other Falcos) were completely covered by the rising waters. Nustrini cleaned, dried and flew his Falco two days later. During the testing of the airplane following the flood, Nustrini dived the airplane to the design speed, and the canopy top broke in a "U" shape from one screw hole to another. You can see the patch for the canopy break on the photo on the back of our Falco brochure -- the shot with all of the kids in the back. I should also mention that there were not six in that Falco, there were actually seven, but you can't see Giovanni who is on your right.
There is no elevator trim on Nustrini's Falco. He took it out to save weight, and now uses a bunch of rubber bands which he hooks to the right control stick once in the air. He also has some other rubber bands which he uses for aileron and rudder trim. There is no wing walk surface on the airplane, and Nustrini has a rubber mat which he puts on the wing and then pulls into the cockpit. Before races, he installs adhesive-backed foam strips between the ailerons and flaps and at other openings. Also he rubs the airplane with talcum powder (?!) saying that the talcum powder fills in the little holes in the paint.
The seats are nearly useless. They are fiberglass seats with no cushions, and they rest on a tubular steel contraption allowing quick seat removal. The seats lean back at an impossible angle, and the seat backs extend up only about 12" which is not enough to give you full support. Once over Florence, I leaned back to put my camera in the back when Nustrini banked the Falco in a high-G turn. The seat provided little support, and I was only able to rescue myself from tumbling into the luggage compartment by grabbing my leg and pulling myself up with that assistance. Nustrini never leans back and only flies the airplane leaning forward, holding the stick with both hands, one at the bottom and the other at the top. The aircraft is painfully noisy, and I made the short flight without the benefit of a headset.
The engine compartment was something of a surprise for me. I thought that Nustrini had done some real magic here, but he had not. He has two oil coolers mounted on each side of the engine, and with the exception of the new nose bowl and ram air induction, it was all standard Falco. The openings for the cooling air seemed to be of the same size as normal, and since his spinner is rather small, he still has a blunt area between the air intake and the spinner to cover the starter ring. There is no cabin heat system.
In the air, Nustrini's Falco behaved like other Falcos except that the airplane was more stable in pitch (due to the nose-heaviness) and had heavier controls (probably due to the higher speed of the airplane), but the controls were still light by normal standards.
Stelio Frati and Luciano Nustrini
As I mentioned earlier, Nustrini's Falco does not have a top speed of 234 mph. That speed was measured from a standing start and around pylons! During our flight, I saw indicated speeds of 300 km/hr (186 mph) at 2000 feet, 20" and 2300 rpm. This is the top of the green speed for me and a speed I have to dive to attain, as in the entry for a loop. The real mind-numbing experience was when Nustrini opened it up. We were at one thousand feet, and the temperature was 80° outside. The two window vents were open, and Nustrini shoved the throttle all the way in. The prop pitch was put on full fine, and it indicated 2800 rpm. The indicated airspeed stabilized at 375 km/hr (232.5 mph) for a true airspeed of about 244 mph. I have found with my Falco that the speed increases as you burn off fuel by about 7 mph, so I would imagine that Nustrini is able to hit some very impressive speeds with little fuel, one on board, windows closed, and with full race preparation.
It was a little much to take in at one time. My experience with airplanes has been that the indicated airspeeds do not increase so rapidly with the increase of power. With Nustrini's airplane, it was a little as if he had suddenly invoked the "force," and we were being towed along by some invisible line. We held this speed for about three minutes and approached a nearby hill which rose about 200 feet above us. Nustrini held it dead level until the absolutely last minute, then pulled it up, and we sailed over the hilltop. Nustrini is crazy about speed, and he gets a broad grin across his face after pulling such a stunt. Recently, in the Tour of Italy race, there was a leg which began with a pylon turn on the beach of one island and ended at a pylon on top of a 4000' mountain at the next island 36 miles away. Nustrini flew the entire leg at 10 feet above the water and did a zoom-climb at the mountain. On this leg, he picked up two minutes on the SF.260s that did a cruise climb.