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GOT: The Ambrosini SS.4 / SAI 107 - 207 - 403

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#21 Romantic Technofreak

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Posted 24 February 2005 - 04:21 AM

I am not an aircraft engineer, but I think the idea behind the canard style is that it is even more safe than the conventional design. Burt Rutans VariEze (hope I remember this fact right) is considered to be unstallable...!![8)]

#22 amigojeff

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Posted 24 February 2005 - 01:30 PM

In the 1940s,such canard plane was rather a dream.It's ok when the speed was relatively low,but when the speed rises,the pilot couldn't control the plane effectively without modern technique like electric flight control.A SS4 prototype was lost due to accident.

#23 Vespasiano

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Posted 24 February 2005 - 02:45 PM

But now, many jets have these wings...

#24 Romantic Technofreak

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Posted 13 March 2006 - 02:49 AM

Friends, you see that I am not regularly able to join the forum in the moment. But for this topic here I found a new source, the website of the Gruppo Modellistico Sestese:

http://www.giemmeses...tori_aerei.html

from the town of Sesto San Giovanni in Italy.

In the opening post, I said there is not much about the Ambrosini S.S.4, but by the website above I could close the gap. The article is again by Giorgio Dorati, we know him already from the as author of the CANT Z.1018 original article. For the Gruppo, he wrote something about every mentioned airplane. Translation was done using Babelfish. More than this, there are fine new pictures of this airplane, and I don´t want to hide them from you. For me, another chance to extend this topic by a new -and sad - part. Now let´s read about

The Ambrosini S.S.4

By continuing the activity of Ing. Sergio Stefanutti at the S.A.I. (Societa Aeronautica Italiana, with location and school of pilotage in Castiglione del Lago), after the harmonic absorption of its shares by the Ing. Angelo Ambrosini firm, with the ideas already expressed previously through wooden power-driven glider S.S.2 of 1935 and the successive S.S.3 Anitra (= "duck") (MM.372) of 1937, the S.S.4 (means Sergio Stefanutti model 4) appeared, being his last evolution of a canard airplane. The idea of the Ing. Stefanutti turned out to be based on an entire inner metallic structure in light alloy and covering in wood, in which the motor (a Isotta Fraschini Asso XI RC.40 delivering 960hp.) came berthed to one fuselage basing on 2 longerons. The wings based on a bispar, and a completely retractable three-wheel undercarriage completed the structure. Vertical and horizontal tail units were finished the same way.

The armament, concentrated in the snout, thus being absolutely unhampered, was constituted by 2 Mauser guns of 20mm and one gun of 30mm (never mounted on the prototype). The motor, positihoned to the "shoulders" of the cockpit, set in action a three-blade pusher propeller of variable pitch in flight. The plan, to have it registered like MM.387 by the military administration, came to realization at the beginning of 39. The 07/03/39 detached its first flight in Castiglione del Lago under the commando of test pilot Ambrogio Colombo. Stating good flight characteristics, the same test pilot demanded of being able to perform another flight.
During the new flight, carried out the 08/03, the pilot had to interrupt the test and tried to return to the same airport. During this maneuver, unfortunately the aircraft ended outside of the track crashing into trees. In the collision the motor block came ahead, causing the death of the pilot.

The at once started inquiry established that the vibrations transmitted from the motor to the metallic structure lead to the separation of an aileron, the same aileron that turned out to have been mounted in a wrong way. Although acquitted, due to the unfortunate circumstances, the aircraft looked too advanced for the high commandos, and subsequently the whole project was abandoned.


Here the pictures:

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Personal remark: I love canard designs. But that´s exactly the trouble with them - one landing accident, and the motor smashes you! (Looks like Vespasiano wasn´t so wrong with his opinion...[:I])

Bibliography given by Dorati:

- Brotzu/Caso/Cosolo – Dimensione cielo – Ed. Bizzarri
- Evangelisti – Gente dell’aria – Ed. Olimpia
- Evangelisti – Macchine bizzarre nella storia dell’aviazione – Ed. Olimpia
- Lennon – Canard. A revolution in flight. – Ed. Aviation Publishers

Hope you enjoyed, RT


#25 montanamotor

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Posted 29 May 2006 - 05:02 AM

Hi, Romantic Technofreak!

For some years now, I am considering - together with a friend of mine - to build a replica of a decent WW II-fighter plane in 1/1 scale. I have traced down one certain Marcel Jurca of french origin as the constructor of some SERIOUS wooden fighter-plane replicas, like Spitfire, P 51 Mustang, Messerschmitt Bf 109, Focke-Wulf FW 190 etc.

But then I thought: Why? Why resorting to a replica, if you can have the real McCoy for the same investment? See: The S.A.I. 207 and, 403 Dardo, are such impressive planes (besides using AFFORDABLE engine-Power to sustain REMARKABLE performances, but still being completely out of wood), that you can hardly go passed them without being impressed - if you were going to build a wooden WW II-fighter-plane-replica, just like I am going to do...

And impressed I was, since the first moment I ever read about the outstanding flight qualities and performances of the wooden Ambrosini-wonders. But one question remains: Who holds the construction plans for those outstanding S.A.I.-planes today? I mean, as there were still Ambrosini S.7-trainers being build for the Italian Airforce after WW II up to 1953, there must still be someone to look after the remains (archives, plans, photographs, records, etc, etc.) of the Ambrosini company, which closed her doors in 1957 (approximately)?

Yeah: That's what I'm looking for, Romantic Technofreak: I am SERIOUSLY looking for a decent source for the original, genuine construction drawings for either the SAI 207 or the SAI 403 (and EVERYTHING printed or photographed matter about any other SAI-plane, too!)

What I have found out myself - thanks to the net - up to date, is this: Constructor Sergio Stefanutti (born 1906, no date of decease noted anywhere on the net yet, so PERHAPS still with us - at a mere 100 years of age...!), owner of the Ambrosini S.A.I.-company was Angelo Ambrosini, company was founded in 1930 and closed doors in 1957 (dates vary). The S.A.I.-company was situated in Passignano sul Trasimeno, a village north of Rome at the Lake Trasimeno (Hannibal once beat the devil out of Rome's Legions at the Lake Trasimeno - but that was another war, another time).

QUESTIONS: Well - does ANYONE know anything MORE about Ambrosini, Steffanutti, S.A.I., Passignano sul Trasimeno, or anybody else or anything else, which might bring me any closer to rounding up a set of decent, genuine construction drawings for the 207 or 403, than I do?

THEN PLEASE TELL ME ABOUT IT!

Your assistance in reaching my goal is MOST WANTED, GENTLEMEN!

Whaddoyothink, Romantic Technofreak? Go - or no-go?

Cheers,

Montanamotor

#26 Dogwalker

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Posted 29 May 2006 - 06:10 AM

SAI Ambrosini never closed doors.
First, with the aquisition of IMAM, became AERFER (1955), then, with the fusion with FIAT Aircraft division, became Aeritalia (1969), that is now part of Alenia Aeronautica.

I don't know really if Alenia still have the original technical drawings of the SAI fighters.

It seems that this association has the detailed drawings of SAI S7 (that's structurally very similar to the SAI 207 and probably more adapt to fit a post WWII engine)
www.geocities.com/fiap_ambrosini

While a number of "Ali d'Italia", edited by Giorgio Apostolo, was dedicated to SAI 207 - 403. Its possible that he has the complete drawings, since there were several extract of them in the pubblication.
www.bancaero.it

You can try to contact them.

#27 montanamotor

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Posted 29 May 2006 - 06:45 PM

Hi, Dogwalker.

Your hints on the history of S.A.I. and on possible sources for plans of the S.A.I. 207 and, 403 - and, yes: also on the S7 - are most welcome. Thank you! I will follow them as soon as possible.

Besides: Disregarding the outcome of the battle at the Lake Trasimeno, the ancient Romans back in the first Punican War finally WON their case against Karthago. That's why, today we all speak the Latin Language one way or the other (well, more or less...) ;)

I will try to get in contact with both possible sources for more information of possibly purchasing plans for the S.A.I.-planes. I'll keep you informed of the progress of my project, anyway.

And if any other piece of information on S.A.I. should occur, please feel free to contact me via "the great planes" (What a decent name - love it!) or via my personal email-address [email protected], whenever appropriate.

Thanks again!

Cheers,

Montanamotor



#28 Dogwalker

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Posted 29 May 2006 - 09:23 PM

quote: I'll keep you informed of the progress of my project, anyway.

Don't forget it! I want to see one of them fly.:D

More than technical information i could provide some further part of the story.
First to say, the SAI 403 was not a developement of the 207, but a parallel project.
The 207 was intended to be the "natural evolution" of the SAI 7 and 107, while the 403 was intended to solve some of the 207 expected problems. First the loss in handling due to the heavier wingload (using a different airfoil and tail section), second, the complexity of the construction (that was simplified) and third, the usage of several forein types of wood (the 403 used only types of wood widely avaliable in Italy).
However, during the evolution of the project of the 403 (that was widely made by Ing. Ambrosini, the owner of SAI, and an entusiast aeronautical engineer himself) Ambrosini and Stefanutti came in discord, cause, it seems, Stefanutti thought Ambrosini used too extreme solutions for the 403, especially for the wings, so Stefanutti didn't want his name to be associated with SAI 403.
However, the discord was soonly over, and Stefanutti accepted to design one of the two projected developements of the 403, the SAI 503 (with a 1260 hp Isotta Fraschini Zeta engine), while one of his collaboretors designed the all metal SAI 404 (with the same Zeta engine).
After the war, Stefanutti stated that Ambrosini's solutions were effectively able to dramaticaly improve the handling of the 403.

The main differences between the three aircrafts (S7, 207 and 403) seems to be the wings' airfoil and structure.
the 207 had a 5 spars wing, with an airfoil of the NACA 230xx series. The S7 had a 2 spars wing, with a NACA 2212 airfoil. It can be interesting to find the airfoil used by Ing. Ambrosini for the 4 spars wing of the 403.

#29 montanamotor

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Posted 30 May 2006 - 06:09 AM

Willco, Dogwalker.

I have tried most of the links and names you sent me, already. Sadly enough, the Website of the Alenia Aeronautica is a complete dropout. Someone should tell their webmaster, how to do it right... But no problem. I'll prepare some letters (NOT Email: I have noticed that, in such a sensitive topic, papermail works better!). It may take a week or two, but I am shure I'll find a way to fetch the construction plans - at last.

WHAT did you mention? S.A.I. was preparing an IMPROVED version of the 403? The 404 - with just twice the engine-power? Do you notice that, this plane may have done approx. 850 km/h with 1350 hp? Ups... That's 200 km/h more than a conventional tin-plane would have done on the same power-output. Pew!

Aaaah - guess, what? In Germany, I found a source for some post-war Continental V12-Engines. Aircooled, inverted, 38 L of displacement. 1500 hp WITH EASE! Turbo-supercharged. Guess, where such an engine would fit into PERFECTLY? Yep. [:P]

Well - Who wouldn't like to have a wooden piston-powered prop-plane going at right the speed of a Messerschmitt ME 262 twin-engined jet-plane? I would...

Yes. I will keep you informed, Dogwalker. I Promise. Question: shouldn't we maybe open a new thread on this? Does anyone know how to transfer this last, new thread into a thread of it's own?

Cheers,

Montanamotor :D

#30 montanamotor

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Posted 30 May 2006 - 04:42 PM

Hi, Dogwalker,

okay: It was late last night, and I was overly tired. So, it's the 503, that's the improved WOODEN version of the 403, and NOT the 404. And the proposed engine for it was to have 1260 hp, not 1350 hp. Well - that would still have been enough for well over 800 km/h Vmax.

But: Everything I wrote about the 1500 hp Continental-Engine last night is PLAIN TRUE!

Fact is: Right now, I am deadly sober and painfully awake.

But is this really a desirable state of being...?

CU soon. Cheers,

Montanamotor





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