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Author Topic: Kaman helicopter and non-helicopter projects  (Read 8956 times)

Offline hugo007

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Re: Kaman helicopter and non-helicopter projects
« Reply #15 on: July 21, 2018, 03:30:33 am »
Hi  all,
Some real great Kaman history on the Steven Kaman channel on youtube
https://www.youtube.com/user/swk91356/videos

Offline Skyblazer

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Re: Kaman helicopter and non-helicopter projects
« Reply #16 on: July 21, 2018, 04:33:00 am »
HTK-1

Superb color photo, thanks!

Offline mil

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Re: Kaman helicopter and non-helicopter projects
« Reply #17 on: July 23, 2018, 12:55:31 pm »
first versions of Kaman-1125

Offline mil

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Re: Kaman helicopter and non-helicopter projects
« Reply #18 on: July 23, 2018, 01:10:33 pm »
Kaman-1125

Online hesham

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Re: Kaman helicopter and non-helicopter projects
« Reply #19 on: December 10, 2018, 03:56:45 am »
Good morning my dears and my friends,

here is a Kaman modification to OH-6A to be fan-in-fuselage;

https://apps.dtic.mil/dtic/tr/fulltext/u2/a005049.pdf

Offline 500 Fan

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Re: Kaman helicopter and non-helicopter projects
« Reply #20 on: December 10, 2018, 10:29:50 am »
A nice find, hesham. I saw those drawings in a NASA book at the American Helicopter Museum this year but there was no supporting text. That fills another hole in my research.  :)

Can you say if that PDF is a recent addition to the DTIC website or has it been there all along? I have trawled that for OH-6A-related test reports but I managed to miss this one!

500 Fan.

Offline TomcatViP

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Re: Kaman helicopter and non-helicopter projects
« Reply #21 on: December 10, 2018, 12:53:34 pm »
Strange that Kaman didn't know anything about rotational inertia

Krot = ˝ Iw˛

By enlarging the fuselage (even at equal mass) there were raising the rotational inertia what will in turn augment the necessary power divested in the counter-torque system. I am stunned by this Kaman design. Given the exquisite refinement of their complex meshed rotor, it's re-assuring to see that at least someone there was not a genius...

Especially when structural design of the tail boom were of equal efficiency
Quote from: page38
n, and assuming that the skin is stable, the maximum stress is
617 psi. It is thus clear that an aluminum semimonocoque structure would
be highly inefficient. A skin is required which is self stabilized and
is light; and a low stress allowable is no detriment. A plastic or
fiberglass-skinned sandwich with a foam core is ideal for the application

And then this incredible moment of mud pedling:
Quote from: page50
Thrust is reduced as the tail boom is lengthened; weight is
reduced it constant boom length with a smaller exit area, and it is not
immediately apparent what combination of dimensions is optimum.


Which invariably lead us to (nearly!) this momentary lapse of reason (think Pinkfloyd)

Quote from: page53
Both weight and balance are of major concern in the fan-in-fuselage design.
The tailboom must enclose a large duct area for aerodynamic efficiency,
and is therefore heavier than a tail rotor tailboom. In this particular
design, the offset from the centerline of the tail rotor drive takeoff
in the main transmission to the centerline of the fan makes another gearbox
necessary. In addition, airflow control and turning vanes are
required at the aft end of the boom, and a larger fin area is required
because the yaw moment of inertia is higher. The gross weight is therefore
increased by 7 percent, approximately.

To be latter back  in this complete denial of basic engineering principle:
Quote from: page60
Use of the ducted fan has actually reduced antitorque power. Rotor
power, increased because of higher weight and vertical drag, more than
accounts for the difference in total power.

But then going further down would look like maniacal sadism so I will end there.
 
This absurdity should be taught in Engineering schools ;)


[/Malice]

Moment of Inertia formula (see how at equal mass it increases as the square of R):

« Last Edit: December 10, 2018, 06:08:29 pm by TomcatViP »

Offline quellish

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Re: Kaman helicopter and non-helicopter projects
« Reply #22 on: December 10, 2018, 01:45:50 pm »
A nice find, hesham. I saw those drawings in a NASA book at the American Helicopter Museum this year but there was no supporting text. That fills another hole in my research.  :)

Can you say if that PDF is a recent addition to the DTIC website or has it been there all along? I have trawled that for OH-6A-related test reports but I managed to miss this one!

500 Fan.

DTIC’s own search is not great but google indexes most of their documents - and can pull text out of PDFs  that DTIC can not. Using google to search DTIC often works better

Online hesham

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Re: Kaman helicopter and non-helicopter projects
« Reply #23 on: Yesterday at 03:51:21 am »
A nice find, hesham. I saw those drawings in a NASA book at the American Helicopter Museum this year but there was no supporting text. That fills another hole in my research.  :)

Can you say if that PDF is a recent addition to the DTIC website or has it been there all along? I have trawled that for OH-6A-related test reports but I managed to miss this one!

500 Fan.

Thank you 500 Fan.

Offline Grey Havoc

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Re: Kaman helicopter and non-helicopter projects
« Reply #24 on: Today at 03:55:36 am »
But then going further down would look like maniacal sadism so I will end there.
 
This absurdity should be taught in Engineering schools ;)

Old Cold War disinfo or spy bait document that was accidently put into DTIC, perhaps? Could be even a genuine report altered for such a purpose, and the altered version was unwittingly sent in rather than the real deal.
The sole imperative of a government, once instituted, is to survive.