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    Tandem & Tilt-Rotor Aircraft development

    Tsavo Lion
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    Post  Tsavo Lion on Mon Jun 08, 2020 6:12 pm

    US Army to demonstrate its upgraded Chinook engine

    The CH-47 performance will improve further with those more powerful engines.
    The engines for Ka-102 would be even more powerful.
    Tsavo Lion
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    Post  Tsavo Lion on Tue Jul 07, 2020 9:46 pm

    https://www.janes.com/defence-news/news-detail/us-approves-mv-22s-for-indonesia

    How come they didn't order less expensive coaxials &/ Mi-38s from Russia? Is it because they seek US protection from China like India does?
    Meanwhile: https://www.janes.com/defence-news/news-detail/jgsdf-receives-second-mv-22-osprey-tiltrotor-aircraft


    Last edited by Tsavo Lion on Mon Jul 27, 2020 5:30 pm; edited 1 time in total (Reason for editing : add link)
    Tsavo Lion
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    Post  Tsavo Lion on Thu Sep 10, 2020 5:54 am

    Kamov JSC has finished a synchrocopter sketch design
    https://en.topwar.ru/157243-ao-kamov-zakonchilo-jeskiznoe-proektirovanie-sinhrokoptera.html

    I wonder if a tandem synchrocopter would have any advantage over a regular tandem helo.
    Stealthflanker
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    Post  Stealthflanker on Fri Sep 11, 2020 12:24 am

    Tsavo Lion wrote:https://www.janes.com/defence-news/news-detail/us-approves-mv-22s-for-indonesia

    How come they didn't order less expensive coaxials &/ Mi-38s from Russia? Is it because they seek US protection from China like India does?
    Meanwhile: https://www.janes.com/defence-news/news-detail/jgsdf-receives-second-mv-22-osprey-tiltrotor-aircraft

    Because our army who meant to operate them do seek long range.

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    GarryB
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    Post  GarryB on Fri Sep 11, 2020 11:59 am

    I wonder if a tandem synchrocopter would have any advantage over a regular tandem helo

    Angling the main rotor blades so they can be intermeshed and adding a tail mounted pusher propeller... congratulations.... they just invented a helicopter you can't get near without getting killed...

    That is why the ones actually in service in the US are used almost exclusively as cranes and not passenger transports.

    I would say the best bet is wait a little while longer for electric motor powered helicopters and just use the coaxial design but without the complex gearbox.

    The syncromesh design was one of the earliest.... there was a german helicopter that used it during WWII... it simply wasn't a good idea.
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    Post  Tsavo Lion on Fri Sep 11, 2020 10:50 pm

    Angling the main rotor blades so they can be intermeshed.. 
    I wonder why can't they be at a level parallel to the ground, 1 above the other,  & still be synchronized, just like on CH-46/47s?

    ..and adding a tail mounted pusher propeller... congratulations.... they just invented a helicopter you can't get near without getting killed...

    not if the blades' tips r high enough, the prop is shrouded or the engines r turned off. This Russian design is bigger than the Kaman, since it weighs more.
    https://en.wikipedia.org/wiki/Kaman_K-MAX#Specifications_(K-MAX)


    Last edited by Tsavo Lion on Sun Sep 13, 2020 8:19 pm; edited 1 time in total (Reason for editing : add link)
    GarryB
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    Post  GarryB on Sat Sep 12, 2020 11:18 am

    I wonder why can't they be at a level parallel to the ground, 1 above the other, & still be synchronized, just like on CH-46/47s?

    The only way intermeshed blades could be level would be if they were far enough apart that each blade does not reach the rotor or turning point of the other rotor blade... in other words a tandem rotor helicopter...

    not if the blades' tips r high enough, the prop is shrouded or the engines r turned off. This Russian design is a lot bigger than the Kaman, since it can lift more.

    The only advantage of the intermesh blade rotor system has over the coaxial is its reduced height.

    Intermeshed blades need to be at an angle to each other... that is what intermeshed means two rotor arcs that intersect, so with synchronisation means the blades of one rotor do no go through the rotor arc of the other set at the same time the others blades come through so they don't contact each other.

    Tsavo Lion
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    Post  Tsavo Lion on Sat Sep 12, 2020 7:08 pm

    The only advantage of the intermesh blade rotor system has over the coaxial is its reduced height.
    If need be, they can have longer landing gear like on the Mi-10 so there's no danger in approaching it with blades turning.
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    Post  GarryB on Sun Sep 13, 2020 11:48 am

    That is fine for a crane model, but not so good for a passenger model....

    I also suspect its performance would be limited.

    With a coaxial blade design the rotors are independent so you can run one set of blades at a much higher speed than the other set... the increased momentum would cause the helicopter to yaw like a pedal turn on a normal helo... but the momentum energy of a full set of three blades is vastly more powerful than the force of a small tail rotor.

    It is one of the advantages of the coaxial design because it means you can do pedal turns at much higher flight speeds... for a helicopter gunship it is invaluable because you can point you weapons at something without actually flying directly at it... so flying at a 45 degree angle towards a target you can pedal turn so your weapons are pointing directly at it... fire some rockets or a missile or a cannon pod burst and then take your foot off the pedal and turn back to heading 45 degrees away from the target so any return fire directed at you will miss because while it appears you are pointing your nose at the target you are actually side slipping sideways.

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    Post  Tsavo Lion on Sun Sep 13, 2020 8:06 pm


    As u can see, there's no danger standing underneath its spinning rotors. This type of helo will be even less expensive to produce & use than a large coaxial, with comparable or better performance. 
    https://www.kaman.com/aerosystems/solutions/air-vehicles-mro/k-max

    A large tandem arrangement with intermeshing rotors is also possible, outperforming the CH-47.


    Last edited by Tsavo Lion on Sun Sep 13, 2020 8:21 pm; edited 2 times in total (Reason for editing : add link)
    GarryB
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    Post  GarryB on Mon Sep 14, 2020 6:06 am

    Hahahaha... yeah... no trouble at all when it is 3m up in the air... when it is on the ground however and those blades are 1.5m above the ground when the helicopter is sitting on the ground it is not so safe.... and helicopters manouver by banking so they would turn their nose into the wind an manouver to land or takeoff by nodding forward to go forward or raising the nose up to go backwards.... or tipping left or right to go left or right to position themselves on the ground.

    A normal helicopter has blades above the level of the helicopter which is generally 2m tall or higher so those blades will be 3m or more up in the air depending on the size of the helicopter.

    With this aircraft even sitting level the tips of the blades out to each side could be as low as 1.5m meaning even children will not be safe... and that is when they are sitting level on the ground... when they take off and dip the blades down in the direction they are going to fly the blades could get much lower... such an aircraft could only ever safely be approached from the front... especially because they can rotate in position using pedal turns so those low side blades could come round to the front and back in seconds without any warning at all... the wind might change and the pilot has to turn the nose to compensate...

    Low blades are the biggest killer on ship decks... the tail rotor in western navies... the Russian an Soviet Navies mainly operated coaxials because the advantages of tandems in a much more compact size an no dangerous tail rotors.

    If a coaxial tries to accelerate in a direction without climbing first its main rotor blades can get dangerously low... but they would never perform such a manouver near people on the ground... they would climb up before heading off in a direction.

    Doing so with a syncromesh helicopter you could need to climb higher before you could do that safely and even sitting on the ground or deck with rotors turning you are a threat to crew on the deck anyway.

    There is a reason they are not widely used and mainly used as flying cranes.
    Tsavo Lion
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    Post  Tsavo Lion on Mon Sep 14, 2020 3:24 pm

    With this aircraft even sitting level the tips of the blades out to each side could be as low as 1.5m meaning even children will not be safe... 
    No1 in their right mind & training would stand under those blades while they r accelerating or decelerating- that's true even with conventional helos. 
    For added safety margin, longer landing gear could be used.
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    Post  GarryB on Wed Sep 16, 2020 6:03 am

    When a helicopter lands to take people away... lets say the middle of an open field... this helicopter lands... I agree you never approach a helicopter as it is landing because before it is stable on the ground it can tilt and turn and do all sorts of dangerous things. Once the helicopter is down a synchromesh helicopter with a tail mounted pusher propeller... the only safe way to approach is from directly in front... there is no other safe direction.

    A conventional helicopter with a tail rotor it is pretty much the opposite... approach from any direction except the tail because of the tail blades.

    With a Chinook when you run off the rear ramp you run straight or the gas turbine engines either side the of the rear tail rotor will burn your skin off.

    Perhaps the best synchromesh design would be like the old Mi-4 with the pilot cabin up high sitting on the body... perhaps a ramp door at the front like the Firefly spaceship in Firefly so the pilot can see people as they approach to get on board so he can see them get on or get off and doesn't need to be told when to take off...

    Such a design would not be very sleek and aerodynamic for very high speed flight though.

    Longer landing gear just makes it harder to get in and out of.

    It would also be the equivalent of making the rotor gear higher... in which case they might as well go back to coaxial rotor designs...
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    Post  Tsavo Lion on Thu Sep 17, 2020 7:03 am

    Longer landing gear just makes it harder to get in and out of.
    servo motors/hydraulics could control its height once the engine is stopped or internal deployable ladder could be installed for crew access.
    Pusher props can eliminate the need for tiltrotors, coaxials & side tail rotors, decreasing drag & increasing speed:
      https://www.youtube.com/watch?time_continue=118&v=Yu2CwHwxJYA&feature=emb_logo

    https://www.youtube.com/watch?v=fR-r6RR1nJM

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