A Visit with Frati

by Stephan Wilkinson

This appeared in the September 1988 issue of the Falco Builders Letter.

If anybody ever suggests you go visit Frati "in Milan," as Alfred Scott did when he heard I was going to be in Italy writing about the Piaggio Avanti turboprop, here's my suggestion: get Alfred to pay the cabfare. If you can't do that, buy a car. A small Fiat will do, and it'll probably be cheaper than a cab.

I leapt off the train from Genoa at Milan's central station and plunged straight into a waiting taxi. "Via Trieste Vente-Quattro," I said in my best non-Italian, and about $15 later, that's exactly where he took me-24 Via Trieste. Quiet urban residential street... relatively upscale... odd place for an airplane factory....


Stelio Frati and his first aircraft design, a torpedo bomber done for his master's thesis in 1942

Actually, there was no number 24. We found a phone booth, and my cabbie was nice enough to tackle the Italian telephone system on my behalf. He called Frati's number, and I knew I was in trouble when I saw him perform the classic application of heel of hand smartly to forehead, as though trying to jar loose a subdural hematoma: the Via Trieste that I wanted, it turned out-a street that apparently is the Italian equivalent of "Oak Lane" or "River Avenue," with at least one in each town-was in Pioltello, not Milan. I had done the equivalent of asking for an Arlington address in "Dallas," or somewhere in Berkeley by requesting "San Francisco."

By the time we got there, the driver was steaming, the taximeter was smoking, and the total looked roughly like a loran lat/long readout. (Don't ask about the trip back: I had to pay for the cab both ways on that one.)


Carla Bielli

Was it worth it? Absolutely. Stelio Frati was in fine form, his staff seemed delighted to devote most of a day to a guided tour for me, and his delightful redhead of an assistant Carla Bielli was nice to me even though I got an F in her quiz. Bielli adores the United States, has traveled extensively here, and knows more about the country than most of us. She showed me an aerial photo in Aviation Week, which had just arrived, and asked me to identify it. It was a turn point for some oil-burner route, I think-Sedona or Sonora or Soccoro or something. She'd been there. I hadn't, which she thought suspicious for somebody who claimed to be an American.


Frati in his office

Stelio Frati's small but surprisingly active R&D company, General Avia, is an Italian version of Burt Rutan's Scaled Composites. At least it's what Scaled Composites might be if Rutan were in his mid-60s and a classicist committed to traditional design and materials. Frati's best-known design is, of course, the Siai-Marchetti SF.260, still the fastest normally aspirated piston single in production anywhere. Over 900 have been made, Frati says with modest pride. ("But the Falco is his favorite child, you know," said Bielli.) Few of Frati's designs have seen substantial serial production, but between the SF.260 and the Falco-both the original factory-built models and the Sequoias-the "Fratis" currently flying number well into four digits, which compares well with Rutan's own output.


Jet Squalus and the commuterliner

General Avia builds only prototypes, on contract to a variety of outside manufacturers, and when it's finished with one airplane, it moves on, itchy-fingered and full of ideas, to the next. "Anybody who works at General Avia is a bit of a fantasist," says Frati's longtime associate, a handsome, bearded young aeronautical engineer and pilot, workshop director Renato Cairo. "We could never go into production here, because we'd keep changing things, modifying a design. We could only produce if we made parts-ailerons, say, or tail sections. Never an entire airplane."

General Avia is housed in an anonymous industrial-park building several miles from Linate Airport, a small complex of office rooms in front and two large shop areas out back. The office cat prowls the halls lethargically-"He has been out last night looking for girlfriends," Bielli tells me-and the office lavatory seems largely devoted to catfood bowls. Were it an American company, General Avia would be cranking out lawnmower parts, aluminum screen doors or mobile-home pieces-anything to keep the machinery operating and the shop busy. The pace in Pioltello is slow, craftsmanlike, ruminative, however.

Parked on the shop floor are prototypes past, present and future-some coated with layers of dust and grime, others with aluminum still shiny, yet to be skinned. There is a tip-tanked light twin up on jacks with empty nacelles-one of the early-1970s six-seat F.20 Pegasos-for nobody here leaves wheels, tires, engines, instruments and avionics sitting around in grounded airplanes when they could be employed elsewhere or exchanged for more useful parts. An equally gutted turbine twin with a swing-back bubble canopy is parked nearby-the Condor, a recent quasi-military Allison 250-powered prototype that was put aside when more pressing work came through the door. In the next room is a structure that makes it look as though perhaps General Avia has changed its mind and indeed is going into the mobile-home business: the cabin section of a large, as-yet-unfunded commuterliner. Next to it is the abuilding fuselage of the number-two prototype of General Avia's current project, the Jet Squalus.

The most recent Frati to enter production is the Canguro-the Kangaroo, an appropriate name for a small utility/commuterliner that hops from place to place. The Italians have never been one to sieze the moment, and the Canguro has been a source of some disappointment to General Avia, for the design is already 10 years old yet is only now being put into production by Siai-Marchetti. And at that, it's preceded by decades by the Britten-Norman Islander, for which it was intended to be a turboprop replacement. (One of the first Canguros to go into line service, with an Italian commuter, is registered I-SLAB, an appropriate description of its Islander lookalike shape-not the prettiest Frati design to ever take wing.) One would think that whatever market exists for the Canguro has already been well-tilled by the Turbine Islander, the GAF Nomad and the various turboprop Partenavias.

The Squalus (Shark) is a stone-simple jet trainer commissioned by a brand-new Belgian manufacturer, Promavia, as an economical version of the USAF's since-abandoned T-46 new-generation trainer. Frati thinks that an important role for the Squalus could become that of an ab initio schoolship for airlines suddenly faced by pilot shortages as the lure of that career fades amid the financial hardball of deregulation. Put a baby pilot through a couple of hundred economical hours in a Squalus, Frati says, then pop him or her into a straight-wing Citation for a quick multi-engine syllabus and you've got a new 737 copilot, God help us.

True to Frati's tradition of designing airplanes with superb handling qualities, the Squalus's forte seems to be aerobatics; he plies me with snapshots of the prototype looping and rolling and shows me flight-test reports from a variety of military and air-transport pilots, all of whom rhapsodize about its handling. "When the Squalus comes to America soon, you must fly it," he says, not knowing how quickly aerobatics stimulate my gag reflex. Cairo tells me the standard Squalus maximum-performance demo concludes with a landing approach that turns into a go-around, followed by an immediate loop, a touch-and-go at the bottom of the loop, then a roll and a full-stop landing. All in one pass, within the length of an ordinary runway.

The Squalus's engine is a tubby little Garrett fanjet, the F-109, developed at a cost of $109 million (Do they number them in dollars?) by Garrett and the USAF, for use in the T-46. The F-109 is less than a meter long and weighs barely 400 pounds yet will eventually be uprated to 1,850 pounds of horsepressure. Says Cairo, "The Air Force was not happy that some people use an engine they paid so much money to develop," but after a seven-hour briefing he gave a bird colonel at the Garrett plant in Phoenix, Arizona, General Avia got an engine and full support.

The number-two Squalus prototype is scheduled to get an 1,800-pound-thrust Williams FJ44 fanjet. The Squalus is a splendidly simple little airplane, which suggests that our own Air Force could do worse than ask Frati to crank out a few designs for its own gold-plated inventory. (When I tell Frati that during my earlier visit to Piaggio, I'd learned that the Italian manufacturer had paid $3 million for wind-tunnel-model tests of its Avanti business turboprop design, his eyes widen behind his heavily tinted glasses. He says, "With $3 million, I could pay for the entire Squalus program-development, two prototypes and all.")

Crawl up through the big ventral engine-access hatch and you'll see the fuselage contains no ram-air turbines, APUs, ECUs, FLIRs, tailhooks, miniguns, bang seats or aerial-refueling packs. There's little but the engine, fed by a Y-shaped Kevlar internal duct that leads from a pair of detachable fuselage-side airscoops (also Kevlar) and a single fuel tank behind the cockpit. The tank is hell on crashworthiness, but perhaps the Italians follow the dictates of Ettore Bugatti: they make their vehicles to go, not (suddenly) stop. Frati likes the tank because it's uncomplicated and not oddly affected by unusual attitudes or aerobatics. Besides, he says, you don't need more than 90 minutes' fuel for training flights.

What's penciled in next on Frati's calendar? "The big one," he says: a high-wing, twin-engine, 19-passenger turbofan commuterliner that currently exists only as the boxy section in Frati's shop.

Says Cairo, "There is a difficulty on the commuter: money. The project will be an expensive one, and getting financial support will be difficult. But a new concept we see is a short-haul aircraft of such a sort. The next step for European aviation is connecting towns such as Genoa and Milan (75 miles), Turin and Florence (200 miles). There are dozens of flights a day between Milan and Rome but almost nothing to any other domestic destination. We need small aircraft to connect such towns exactly as a bus does."

I believe it. To reach Milan from Genoa after my Piaggio visit, I'd intended to do exactly what any good American traveling between two major cities does: wander out to the airport and snag the next commuter. Fortunately, an Italian friend laughed and said there was only one flight a day at best, and it went to "Milan's" Malpensa Airport, which is so far from the city it might as well be Zurich's.

There's a lot of publicity in Italy about icing dangers, as the result of a recent domestic ATR42 crash, so Frati is quick to point out that while turboprops fly at the critical-icing altitudes, turbofans climb quickly through it. He also understands that passengers need comfort and quietude if they're to buy tickets. It took aviation a long time to figure this out, and as a result, much of the American public's negative attitude toward "those miserable little prop jobs" is the legacy of the dreadful Fairchild-Swearingen Metroliner, an assumedly efficient and fast little torturebox that nonetheless has come to typify uncomfortable commuterliners.

Frati pored through the packet of in-progress photos that I'd brought of my Falco. He seems stunned and fascinated by the concept of somebody setting out to homebuild this little airplane of his, but it secretly pleases him, too. Frati quickly noted that I was installing stall strips, for he feels that to not do so is idiotic. He wonders if the Aronson and Brown accidents might have turned out any differently if those airplanes had carried stall strips. He insists that the stall strips cost zero knots, and he pointed out that I actually ought to locate the strips after flight testing rather than simply sticking them on the nose of the chord. (Scott disagrees, saying the location isn't that critical.) Finally, Frati formally presented me with a pair of Official Signature-Model Stelio Frati Stall Strips-aluminum and intended for an SF-260 but identical in size and shape to the Falco's.

I asked both Frati and Cairo about Scott's having experienced substandard roll rates in several kit-built Falcos, and Frati said that without knowing exactly in what quadrant of the roll the rate is slow, what speeds are being flown and the like, he suspects the problem is caused by too narrow a gap between wing and aileron. Apparently, an adequate gap is required in order to keep the airflow attached to the aileron. He also says that whatever the evidence provided by the malformed wing of Scott's Corporate Disgrace, a straightedge placed atop the wing should just touch the top of the aileron; there is absolutely no need to have a properly built aileron protrude above the wing profile.

Frati also warns that correct control-cable tension is critical in order to achieve the proper roll rate; if the aileron-cable tension is too low, the rate will suffer.

Cairo's advice was to try the old yarn-and-tape-ridge trick, which he'd used with excellent results on a four-aileron, symmetrical-wing Pitts that had a dismayingly slow roll rate. Build a small ridge-2mm high is plenty, he says-by stretching a length of yarn spanwise under a strip of tape, trying it first on the ailerons themselves just aft of the wing and if that doesn't work on the wing itself just ahead of the aileron. Being an engineer and a proper conservative, Cairo recommends doing it one side at a time and doing first the outboard half of an aileron, then one full aileron, flight-testing in between. He doesn't recommend tape-ridging the full span of both ailerons and then going up and slapping the stick into a corner.

So I've made my pilgrimage to the Lourdes of Lightplanes, and I'll die happy. Something tells me I got there just in time, too: Frati showed me his new CAD computer, and just before my visit was over he pointed out the Collins EFIS boxes that had recently arrived for installation in the number-two Squalus prototype. Imagine: a Frati with electronic flight instruments.

Good Lord: next he'll be making airplanes out of plastic!