Zarvan
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Our economy sucks otherwise if Pakistan can get both KAAN and J-20 it would be AWESOME
Just a Nice Pic....
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fatman17
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Overkill bro
Muhammad Saftain Anjum
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We would have developed our own if our economy was in good shape.
But Generals can't tolerate a strong Pakistan.
Gripen9
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Pakistan AF operated these HH43 Huskies back in the day for SAR. I saw one flying early 1980s.
Gomig-21
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Wow, very cool, I never knew that. I thought this was a new concept.
That intermittent technology reminds me of the interrupter or synchronizer gear invention the German Fokker Eindecker introduced back in 1915 to allow the machinegun to fire between the propeller blades. This must be close to that or something along the same lines.
Gripen9
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yeah the huskies were unique at that time. Produced back in late 50 early 60s. But very hard to maintain.
The interrupter was revolutionary for its time.
Bilal9
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The two sets of rotors intermesh in such a way that they never even come close to each other's blades. Kind of like egg-beater blades but wider. This is officially designated Twin non-coaxial rotor configuration. The idea was credited to German aerospace engineer Anton Flettner from before WWII.
Kaman HH-43 Huskie - Wikipedia
Here are snippets from all Helicopter blade arrangements
- Question: I have seen helicopters on TV shows that only had ONE main rotor and NO tail rotor, so how do they work?
Answer: As you may know, yaw is the ability of a vehicle to rotate from left to right. In previous answers concerning the yaw control of helicopters (#1 and #2), we discussed how a tail rotor is used to maintain yaw control and counteract the torque effect. Since that time, we have received several more questions regarding how helicopters without tail rotors maintain yaw control. Hopefully this week's answer will help clear up some of the confusion.
To fully understand the purpose of tail rotors and helicopter yaw control, we must go back in time to the 1600s when Sir Isaac Newton developed his laws of motion. Newton's third law of motion, in its popular form, says that "Every action has an equal and opposite reaction." Keeping this in mind, think of a typical helicopter with a single rotor. As the rotor spins clockwise at a high rate of speed, there is an equal and opposite reaction acting on the helicopter fuselage making it want to spin counterclockwise. To keep the helicopter from becoming a flying pinwheel, we must somehow exert a force on the fuselage to counteract that of the main rotor. Notice that I haven't said anything about tail rotors yet. In fact, if a helicopter were to be flying forward fast enough, a vertical tail like that used on an airplane would provide enough force to counteract the torque of the main rotor, without any tail rotor! In fact, this mode of flight is actually one of the emergency procedures recommended when a tail rotor malfunctions. Of course, one of the reasons helicopters were developed in the first place was the desire to hover over one spot with no forward velocity. This requirement then brings us back to the need for some kind of force to counteract that of the main rotor.
Depending on who you ask and how you count, there are four different ways to counteract the force of the main rotor: a tail rotor, twin non-coaxial rotors (either tandem, side-by-side, or intermeshing), twin coaxial rotors, and the NOTAR system. We believe that NOTAR is the particular method you are referring to in your question, but let us explore each of these options for the sake of completeness.
Tail Rotor:
Tail rotor configuration
By far the most common method for yaw control was first used by Igor Sikorsky in 1941. Sikorsky's configuration featured a single main rotor with a small tail rotor mounted at the end of a long tail boom, as exemplified by the AH-64 Apache. While the main rotor generates the lift and thrust that make flight possible, the purpose of the tail rotor is to counteract the torque effect. The tail rotor works much like any propeller or rotor. It spins at a high rate of speed, accelerating air in a specific direction, to create a force in the opposite direction that counteracts the force of the main rotor. The pilot of the helicopter can alter the properties of the tail rotor to increase or decrease this force thereby causing the helicopter to yaw to either the left or the right. To maximize the force of the tail rotor, the rotor is usually mounted on a considerably long tail boom. There are two notable disadvantages of this arrangement. First, the long tail boom creates an aircraft with a large "footprint," meaning it needs more space for maneuvering and storage. Second, while the helicopter is on the ground, the spinning tail rotor is usually low to the ground so that it presents a hazard, often a fatal one, to ground crew.
Keep in mind that this approach is only ONE way to counteract the torque effect, and while it is the most common, it is generally considered the most complex! Just like a car isn't the only way to get around town (I personally use a human-powered spring, aka a pogo stick), the tail rotor isn't the only way to counteract the torque of a helicopter rotor. - kopiosatu
24 Oct 04, 15:51
Twin Non-Coaxial:
Twin non-coaxial rotor configurations, tandem rotors and side-by-side rotors
If you are going to build a large helicopter for lifting heavy loads, then it makes sense to use two separate rotors to generate more lifting force. If these rotors are separate, such as those on the CH-46 Sea Knight or the V-22 Osprey, then they are called "non-coaxial," meaning they do not share the same axis. Since these helicopters have two rotors that are usually equal in size, the simple solution to the yaw control problem is to spin the rotors in opposite directions. Thus, the yaw forces created by each rotor cancel each other out. Yaw control is achieved by tilting the rotors in opposite directions (to the left and right in the case of the CH-46).
Twin non-coaxial rotor configurations, intermeshing rotors
A subgroup of twin non-coaxial rotors is the twin intermeshing rotor system, seen only on a few helicopters made by the Kaman company, including the H-43 Husky and K-MAX. The principles by which intermeshing rotors operate are the same as those previously discussed for other twin rotor helicopters. The difference is that the rotors are mounted very close together and actually intermesh, i.e. the blades on one rotor travel through the rotor disk of the other rotor. Of course, the intermeshing of the rotors is carefully timed to keep the rotors from chopping each other to pieces. There aren't many flyable H-43s left, but when they are airborne, they are indeed an interesting sight. - kopiosatu
24 Oct 04, 15:53
Twin Coaxial:
Twin coaxial rotor configuration
Another yaw control strategy pioneered by the Russian manufacturer Kamov utilizes two rotors that share the same axis (coaxial), an example being the Ka-50. Much like the non-coaxial design, the rotors rotate in opposite directions, each one counteracting the yaw force of the other. Yaw control is achieved by increasing the blade pitch on one rotor while decreasing the pitch on the other. The result is a differential in torque, resulting in a yawing motion. The most notable advantage of the twin coaxial arrangement is that it is very compact. Although the twin rotor configuration tends to be rather tall, the lack of a long tail boom results in a very short fuselage that takes up much less space. For this reason, Kamov designs have proven very popular for shipboard use with the Russian Navy.
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mil-avia
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