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Sikorsky S-57 (XV-2) single-blade rotor project

Stargazer2006

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Sikorsky's model history is pretty well known, but the undesignated projects that never left the drawing board do not appear that often.

I have a question concerning something that was called the Skyshark. And no, I didn't mean Douglas here! The name appeared, along with a logo, in Sikorsky's in-house bulletin circa 1971, with no further explanation. I attach the logo for reference. Could it be a naval helicopter project? Or a missile of some kind? I must say I never found anything else on the subject...

Incidentally, I find a reference for an article entitled "The Incredible Skyshark--First Amphibious Jet" in the Apr. 1971 issue of Popular Mechanics. Wonder if this could be related to it?
 

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overscan (PaulMM)

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Popular Mechanics article here. Doesn't seem to be Sikorsky related.

http://books.google.co.nz/books?id=qtcDAAAAMBAJ&pg=PA77&dq=The+Incredible+Skyshark+First+Amphibious+Jet&client=firefox-a#v=onepage&q=The%20Incredible%20Skyshark%20First%20Amphibious%20Jet&f=false
 

Stargazer2006

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Thanks for the link! Didn't know that old Popular Science issues were available on line...

Obviously this Skyshark is NOT a Sikorsky-related design. Sikorsky's Skyshark must have been another project... (unless they provided their engineering experience to the building of the mock-up, but I don't really see this happening, considering they hadn't done flying-boats in three decades!)
 

Dynoman

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Stargazer, the Skyshark may have been the XV-2 (XH-36) single bladed aircraft, but it was cancelled before any hardware was developed. It was a study project during the Korean War. Cancelled 1960.



Note: Only assumption is that the fixed wing Sky Shark a was a development at the same time as the XV-2. Quite a stretch.
 

fightingirish

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Another picture of the proposed Sikorsky S-57 (XV-2/XH-36)

Source (found by member hesham :) ):
http://books.google.com.eg/books?id=eE-trX3XZawC&pg=PA75&dq=sikorsky+S-57#v=onepage&q=s-57&f=false
Maybe someone can attach a screen shot.
 

hesham

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Hi,

here is the Sikorsky S-57 with anther Sikorsky projects.
 

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Arjen

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Some data on the S-57 convertiplane project:
It utilises a single-blade counter-balanced rotor to take off as a helicopter. When sufficient forward speed has been built up for the fixed wing to take over, the rotor is stopped and retracted into the top of the fuselage. The S-57 has obvious possibilities as a high-performance tactical strike or reconaissance aircraft. Its power plant is a Pratt & Whitney JT-12 turbojet.
Source: John W.R. Taylor, Helicopters, Ian Allen Ltd, 1960. A 64-page booklet I dug up years ago.
 

Stargazer2006

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I know that the following is not exactly in its proper place here, but since it's not MY work I can hardly feature it in the "User artwork" section... and I just couldn't resist sharing it with those who haven't seen it yet!

A very talented Belarussian called Alexander ("slava_trudu" on the What If forum) produced in 2008 this magnificent set of fake illustrations of the XV-2 using a scale model he had built as a basis.

I'm enclosing the photos of his model in this post. More pics in the next...

 

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Jos Heyman

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Beautiful pics, and I bet you, in 50 years time there will be some historian who will declare them as 'the real thing'.
Oh well, unfortunately I can be fairly sure that I will not be around to correct them at that time.
 

Jemiba

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In 50 years ??! We can be glad, when they not already show up on a site, we can only look
at the pictures, but not read the text. Probably we should add a rule to the forum rules,
saying that all artwork, that could lead to deception has to carry a "FAKE !" watermark ... ;)
A little bit of nitpicking (not too serious !): Perhaps the lights should show a more "dynamic"
flightpath, no so "heli-like" ? ;D
 

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Stargazer2006

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Fascinating! This looks a lot more like a "Skyshark" than the S-57... (see the first post in this topic).

I've tried to isolate and enlarge that beast:
 

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Grey Havoc

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A proposal for the DASH requirement?
 

hesham

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hesham said:
Hi,

here is the Sikorsky S-57 with anther Sikorsky projects.
A clearer view;

http://archive.aviationweek.com/search?exactphrase=true&QueryTerm=crane&start=80&rows=20&DocType=Article&Sort=&SortOrder=&startdate=1944-11-27&enddate=1980-10-23&LastViewIssueKey=&LastViewPage=
 

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Stingray

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How this machine find aerodynamic balance?
In VTOL mode the single rotary-wing was to have a counterweight with a pressure-jet nozzle at the tip. This aspect of the design is technically feasible, as counterbalanced single-blade rotors have been tested successfully by others in history (the Bo 103, for example, though in much later time period, was capable of hands-free flight), but don't boast much in efficiency compared to conventional designs (also see here; it was tested on an R-4 during a very early stage in the project). The attraction here though is the potentially compact form since its less complex when stowed in high-speed jet mode, compared to later designs when the project was shortly revived to experiment with a more conventional two-bladed, stowable rotary-wing (think early X-wing type of design). There were provisions in the VTOL design to prevent excessive blade flapping at low rotor speeds, but it was found in the revised two-blade design that significant pitch and roll issues would still be present upon the initial rotation of the rotor.

There were different wind tunnel models of each configuration tested at NASA Ames, but I'm having trouble finding specific data about these tests online.
 

litzj

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How this machine find aerodynamic balance?
In VTOL mode the single rotary-wing was to have a counterweight with a pressure-jet nozzle at the tip. This aspect of the design is technically feasible, as counterbalanced single-blade rotors have been tested successfully by others in history (the Bo 103, for example, though in much later time period, was capable of hands-free flight), but don't boast much in efficiency compared to conventional designs (also see here; it was tested on an R-4 during a very early stage in the project). The attraction here though is the potentially compact form since its less complex when stowed in high-speed jet mode, compared to later designs when the project was shortly revived to experiment with a more conventional two-bladed, stowable rotary-wing (think early X-wing type of design). There were provisions in the VTOL design to prevent excessive blade flapping at low rotor speeds, but it was found in the revised two-blade design that significant pitch and roll issues would still be present upon the initial rotation of the rotor.

There were different wind tunnel models of each configuration tested at NASA Ames, but I'm having trouble finding specific data about these tests online.
thanks for your nice answer stingray!
 

riggerrob

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How this machine find aerodynamic balance?
A single main rotor blade is never aerodynamically balanced. It just rotates so fast that the right side never has time to fall out of the sky before the single blade reappears overhead. IOW single-blade rotors have low frequency vibrations (1 per revolution) but massive amplitude vibrations.
If you thought two-bladed Bell Hueys had annoying vertical vibrations (2 to 1), … they are mild compared with single-blades.

The only production examples were single-bladed, wooden propellers made during the 1930s for Piper Cubs. Early Piper Cubs started with 40 horsepower and needed all the help they could get. The single-bladed propeller was able to self-adjust pitch from climb to cruise pitch without any mechanisms aft of the prop hub.
Aeromatic later refined the concept for self-adjusting, two-bladed propellers which enjoyed some success during the late 1940s. These flivers were far too light to carry hydraulically-controlled propellers with constant-speed governors. However, the long term solution was greater engine displacement producing more horsepower.
 
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