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Fairchild M-232 STOL

Abraham Gubler

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Found while trolling through Google for STOL data. The Fairchild M-232 STOL test bed using the wing in slipstream technique of the Crouch-Bolas Dragonfly. Kind of a proto OV-10...

http://www.flightglobal.com/pdfarchive/view/1956/1956%20-%200005.html

Fairchild M-232 experimental short take-off and landing aircraft powered by two Lycoming SO-580 flat-eight piston engines driving airscrews through shafting:
Span, 39ft; length in flying position, 29ft 6in; length of nacelle, 18ft 4in; distance between centre lines of airscrews, 17ft; ground angle, 25 deg (landing) or 22 deg (take-off). Maximum weight, 7,000 Ib; accommodation, pilot plus passenger; also provision for belly nacelle accommodating eight men or four stretchers. Short-field requirement, to be able to use 500ft clearing with 50ft-high surround; cruising speed, 242 m.p.h.
 

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Jemiba

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Another 3-view and a description of the M-232 from The Aeroplane .1.56 :
 

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Kokoro

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I assume the engines were meant to be IO-720s, 2x400hp to get the 800 quoted.

The engines had cooling problems in Comanches so I assume with this machine they might have some sort of extra cooling from somewhere.

Edit: just read Abraham's original post again where it mentions O-580s, six cylinder engines without the cooling issues. But they are only 300hp each. So at least two types of lycomings where considered for the design, the eight mentioned in Jemiba's description and the six. O-720 and O-580.
 

AeroFranz

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Cool find. I hadn't seen such a long nose gear arrangement since the Cutlass :eek:
 

Abraham Gubler

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AeroFranz said:
Cool find. I hadn't seen such a long nose gear arrangement since the Cutlass :eek:

It looks like it might be quadcycle gear with those semi circles in the second three view being the semi enclosed folded position of the wheels.
 

AeroFranz

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Abraham Gubler said:
It looks like it might be quadcycle gear with those semi circles in the second three view being the semi enclosed folded position of the wheels.

a la XC-120 Packplane? That was my first impression too, and yeah, those semi-circles must be the retracted wheels. I was having a hard time figuring out the geometry though, what with the front gear being much longer than the rear. But I guess the front gear can be hinged at the 'chin' of the nacelle, with the elements swinging back, and the shorter rear wheels retracting forward.
The tricycle gear would work too, but the quadricycle definitely affords better protection to the props.
I wonder if those skinny engine nacelle extensions were necessitated by the need to provide some ground clearance to the props.
 

Abraham Gubler

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AeroFranz said:
a la XC-120 Packplane?

And the Burnelli planes, I believe it was his patent.

AeroFranz said:
That was my first impression too, and yeah, those semi-circles must be the retracted wheels. I was having a hard time figuring out the geometry though, what with the front gear being much longer than the rear. But I guess the front gear can be hinged at the 'chin' of the nacelle, with the elements swinging back, and the shorter rear wheels retracting forward.

That forward gear is a strange looker. Why do they have that big cowling? A lot of drag? Looking at the side view maybe the forward gear head is mounted on a rail and slides forward until it locks level with the leading edge of the wing (see attach). It fits the geometry but why would they bother? Surely a conventional pivot with a 90 degree swing would do the job a lot easier but those wheels are drawn where they are.

AeroFranz said:
The tricycle gear would work too, but the quadricycle definitely affords better protection to the props.
I wonder if those skinny engine nacelle extensions were necessitated by the need to provide some ground clearance to the props.

I think the propeller extensions are to get the most out of the slipstream on the wing as this is a key part of the STOL capability. Like the Zimmerman ‘flying pancakes’ and XF5U.

The engines on the Fairchild STOL look like they are transverse mounted, head to head, which certainly solves cross shafting issues. An interesting engineering solution to that problem.
 

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Stargazer2006

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The so-designated "Fairchild Model M-232" is, in fact, the Hunt "Dragonfly" type aircraft Model HD-7 which is entirely my own concept, originally as the HD-6 and then HD-7 (4-22-53) which incorporates the patented Hunt Power-Lift Principle (US Pat. 2650045).

In 1953, a private venture engineering and construction program was entered into between the Fairchild Engine & Airplane Corp. and the Wiggins-Hunt Engineering Corp., together with Albert E. Bloomquist & Assoc., Ringoes, N. J., to design and build the Model HD-7 "Dragonfly" in Norwood. Mass., on the premises of Wiggins Airways Inc. In addition, a licensing agreement exists between Fairchild Corp. and Wiggins-Hunt Engr. Corp. for the use of the Hunt Power-Lift Principle.

Except for final assembly, the complete HD-7 project has been carried on at Norwood, completely divorced from the Fairchild Aircraft Division up until September of this year, at which time the project was moved to Hagerstown for testing and final assembly.

It might be of interest to you to know that the present HD-7 "Dragonfly" stems directly from the original Mk. I "Dragonfly," with which I was also connected during 1932-37. The original Bolas Patent No. 1,933,307 was assigned to me in 1949 prior to its running out in 1950, at which time my application went in. The patent was issued to me in 1953.

WILLIAM E. HUNT Vice President Wiggins-Hunt Engr. Corp. Norwood, Mass.

Source: American Aviation, Volume 19 (1956)
 

hesham

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Hi,

the Patent bt William E. Hunt was the basis for Fairchild M-232 aircraft.

http://archive.aviationweek.com/issue/19551219#!&pid=28
 

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Stargazer2006

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The entire article in full size:
 

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