Interesting Helicopter Types

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Cacophonix
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Interesting Helicopter Types

#1 Post by Cacophonix » Tue Dec 18, 2018 3:14 am

Kaman K-Max

I was fascinated to see the intermeshing main rotors (synchropter) and the lack of a tail rotor on this extraordinary type. With servo operated controls and a simplified hub this aircraft is a prodiguous lift aircraft, optimised for load carrying...



I
n 1947 Anton Flettner, a German aero-engineer, was brought to the United States as part of Operation Paperclip. He was the developer of the two earlier synchropter designs from Germany during World War II: the Flettner Fl 265 which pioneered the synchropter layout, and the slightly later Flettner Fl 282 Kolibri ("Hummingbird"), intended for eventual production. Both designs used the principle of counter-rotating side-by-side intermeshing rotors, as the means to solve the problem of torque compensation, normally countered in single–rotor helicopters by a tail rotor, fenestron, NOTAR, or vented blower exhaust. Flettner remained in the United States and became the chief designer of the Kaman company. He started to design new helicopters, using the Flettner double rotor.

The K-MAX series is the latest in a long line of Kaman synchropters, the most famous of which is the HH-43 Huskie. The first turbine-powered helicopter was also a Kaman synchropter.

The K-1200 K-MAX "aerial truck" is the world's first helicopter specifically designed, tested, and certified for repetitive external lift operations and vertical reference flight (Kaman received IFR Certification in 1999), an important feature for external load work. Other rotorcraft used for these tasks are adapted from general-purpose helicopters, or those intended to primarily carry passengers or internal cargo. The K-MAX can lift almost twice as much as the Bell 205 using a different version of the same engine. The aircraft's narrow, wedge-shaped profile and bulging side windows give the pilot a good view of the load looking out from either side of the aircraft.

The transmission has a reduction ratio of 24:1 in three stages, and is designed for unlimited life. The rotor blades (which turn in opposite directions) are built with a wooden spar and fiberglass trailing edge sections. Wood was chosen for its damage tolerance and fatigue resistance; and to take advantage of field experience and qualification data amassed from a similar spar on the HH-43 Huskie helicopter, built for the U.S. Air Force in the 1950s and 1960s. The pilot controls blade pitch with tubes running inside the mast and rotor blades to move servo flaps that pitch the blades, reducing required force and avoiding the added weight, cost and maintenance of hydraulic controls.

The K-MAX relies on two primary advantages of synchropters over conventional helicopters: The increased efficiency compared to conventional rotor-lift technology; and the synchropter's natural tendency to hover. This increases stability, especially for precision work in placing suspended loads. At the same time, the synchropter is more responsive to pilot control inputs, making it possible to easily swing a load, or to scatter seed, chemicals, or water over a larger area.
https://en.wikipedia.org/wiki/Kaman_K-MAX

Based up on the Flettner 282 Kolibri the Kaman design is a very interesting one indeed!

https://en.wikipedia.org/wiki/Flettner_Fl_282

Fl 282 Kolibri.JPG

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Re: Interesting Helicopter Types

#2 Post by G~Man » Tue Dec 18, 2018 6:42 am

Work with them on fires many times. They have wood blades, and without a tail rotor they are almost silent....they can sneak up on you easily.
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Re: Interesting Helicopter Types

#3 Post by unifoxos » Tue Dec 18, 2018 7:41 am

Amazing machine. The mind boggles at the complexity of the controls, particularly to effect yaw.

Slightly less exciting but considerably more prolific, also invented by Anton Flettner, is the "Flettner vent" - that rotating ventilator that is seen on the top of vans used by butchers, dog handlers etc.
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Re: Interesting Helicopter Types

#4 Post by Boac » Tue Dec 18, 2018 7:59 am

Not forgetting his work on the Magnus effect (due acknowledgements to our resident :))) producing the Flettner rotor.

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Re: Interesting Helicopter Types

#5 Post by Cacophonix » Tue Dec 18, 2018 8:44 am

Boac wrote:
Tue Dec 18, 2018 7:59 am
Not forgetting his work on the Magnus effect (due acknowledgements to our resident :))) producing the Flettner rotor.
Here is a brief video of a more recent attempt to use the Magnus effect to fly a microlight aircraft to, not alltogether, good effect.



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Re: Interesting Helicopter Types

#6 Post by Cacophonix » Tue Dec 18, 2018 8:57 am

The Eurocopter (Airbus) X3 High Speed Helicopter (Prototype)

Pronounced x cubed.

Not an operational type per se but fascinating nonetheless...




Technology

The X³ demonstrator is based on the Eurocopter AS365 Dauphin helicopter, with the addition of short span wings each fitted with a tractor propeller, having different pitch to counter the torque effect of the main rotor. Conventional helicopters use tail rotors to counter the torque effect. The tractor propellers are gear driven from the two main turboshaft engines which also drive the five-bladed main rotor system, taken from an Eurocopter EC155.

Guest pilots describe the X³ flight as smooth, but the X³ does not have passive or active anti-vibration systems and can fly without stability augmentation systems, unlike the Sikorsky X2. The helicopter is designed to prove the concept of a high-speed helicopter which depends on slowing the rotor speed (by 15%) to avoid drag from the advancing blade tip, and to avoid retreating blade stall by unloading the rotor while a small wing provides 40–80% lift instead. The X³ can hover with a pitch attitude between minus 10 and plus 15 degrees. Its bank range is 40 degrees in hover, and is capable of flying at bank angles of 120 to 140 degrees. During testing the aircraft demonstrated a rate of climb of 5,500 feet per minute and high-G turn rates of 2Gs at 210 knots.


Performance

The X³ first flew on 6 September 2010 from French Direction générale de l'armement facility at Istres-Le Tubé Air Base.[citation needed]

On 12 May 2011 the X³ demonstrated a speed of 232 knots (267 mph; 430 km/h) while using less than 80 percent of available power.

In May 2012, it was announced that the Eurocopter X³ development team had received the American Helicopter Society's Howard Hughes Award for 2012.

Eurocopter demonstrated the X³ in the United States during the summer of 2012, the aircraft logging 55 flight hours, with a number of commercial and military operators being given the opportunity to fly the aircraft.

With an aerodynamic fairing installed on the rotor head, the X³ demonstrated a speed of 255 knots (293 mph; 472 km/h) in level flight and 263 knots (303 mph; 487 km/h) in a shallow dive on 7 June 2013, beating the Sikorsky X2's unofficial record set in September 2010, and thus becoming the world's fastest non-jet augmented compound helicopter.


https://en.wikipedia.org/wiki/Eurocopter_X³

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Re: Interesting Helicopter Types

#7 Post by Sisemen » Tue Dec 18, 2018 9:37 am

Here’s another “interesting helicopter type” :ymdevil:
610688F5-64EA-4EA3-9897-BC9D5FB62D01.jpeg
610688F5-64EA-4EA3-9897-BC9D5FB62D01.jpeg (131.17 KiB) Viewed 544 times

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Re: Interesting Helicopter Types

#8 Post by Cacophonix » Tue Dec 18, 2018 9:48 am

Sisemen wrote:
Tue Dec 18, 2018 9:37 am
Here’s another “interesting helicopter type” :ymdevil:
That's a Robinson R44 Sisemen! =))

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Re: Interesting Helicopter Types

#9 Post by Sisemen » Tue Dec 18, 2018 2:34 pm

Oh! She’s in a helicopter is she?

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Re: Interesting Helicopter Types

#10 Post by Cacophonix » Tue Dec 18, 2018 2:47 pm

Sisemen wrote:
Tue Dec 18, 2018 2:34 pm
Oh! She’s in a helicopter is she?
Oh, yes the girl, silly bint, she will catch her death of a cold, sitting around in her suspenders like that, particularly with the R44 doors removed. =))

Fine set of pins on her mind you! ;)))

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Re: Interesting Helicopter Types

#11 Post by Boac » Tue Dec 18, 2018 3:09 pm

Never-the-less, a good picture for those of technical bent (bint?) showing the support and tensioning mechanism on the R44

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Re: Interesting Helicopter Types

#12 Post by G~Man » Tue Dec 18, 2018 6:11 pm

Me flying a few years back---oh and some good photoshop skills.
LaFawnduh2.jpg
LaFawnduh2.jpg (109.84 KiB) Viewed 515 times
B-) Life may not be the party you hoped for, but while you're here, you may as well dance. B-)

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Re: Interesting Helicopter Types

#13 Post by Cacophonix » Wed Dec 19, 2018 10:18 pm

A fine quadruple breasted salute G~Man! ;)))


Bell FCX-001


Still a gleam in the designers' eyes...
On March 7, 2017, Bell Helicopter presented a conceptual, futuristic looking aircraft. The mock-up presented is configured for eight passengers, but will be capable of accommodating up to 12.On top of the aircraft are five "morphing" main rotor blades which aim to allow the tip of each blade to move between different flight regimes.This feature is supposed to maximize efficiency and performance and reduce noise. The airframe is slightly bigger than that of a Bell 412.
https://en.wikipedia.org/wiki/Bell_FCX-001

Bell FCX-001.JPG

http://www.bellflight.com/company/innovation/fcx-001





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