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    Mi-24/35M Hinds: News

    Werewolf
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    Post  Werewolf Wed Aug 26, 2020 7:34 pm

    flamming_python wrote:
    GarryB wrote:Wow... that is a huge speed increase with just new rotor blades... with the huge advantage that it is relatively easy to apply to the entire fleet of helicopters and should allow a performance boost across the entire fleet...

    It's a little misleading I think

    As those blades were tested on the flying lab Mi-24 (based on the Mi-24K), which is single-seat and has no wings. They managed to get that thing up to 400 km/h. I believe the plans call for getting it up to 440-450 km/h with subsequent modifications.

    But still just the blades will provide a speed boost to serial Mi-24 and Mi-28 machines too; even +20-30 km/h would be good

    Yes, these blades are a direct result from the testbed Mi-24K, but it has stubbed wings (lifting wings) which generates ~25% lift.

    You can see this blades on the Mi-24K high speed helicopter testbed.

    Mi-24/35M Hinds: News - Page 7 ?u=https%3A%2F%2Fpp.userapi.com%2Fc638320%2Fv638320954%2F3d8f4%2FzX-S3MvnH2o
    Mi-24/35M Hinds: News - Page 7 ?u=https%3A%2F%2Fwww.globalsecurity.org%2Fmilitary%2Fworld%2Frussia%2Fimages%2Fmi-24k-image03

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    kvs
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    Post  kvs Wed Aug 26, 2020 8:06 pm

    This is non-autoclave infusion composite molding. The wings of the MC-21 are also "cast" this way.

    https://www.compositesworld.com/articles/infused-wing-sheds-light-on-aerocomposites-future

    Those mud hut dwellers!

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    GarryB
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    Post  GarryB Thu Aug 27, 2020 8:48 am

    It's a little misleading I think

    As those blades were tested on the flying lab Mi-24 (based on the Mi-24K), which is single-seat and has no wings. They managed to get that thing up to 400 km/h. I believe the plans call for getting it up to 440-450 km/h with subsequent modifications.

    But still just the blades will provide a speed boost to serial Mi-24 and Mi-28 machines too; even +20-30 km/h would be good

    That is the question though... to what extent were the old blade designs holding back aircraft speeds... on any conventional rotor bladed helicopter you have a rotor blade on one side of the helicopter going forward generating lift and also a blade on the opposite side going backward also generating lift. The airspeed at 300km/h flying forward means the attacking blade... the blade going forward has 300km/h of extra wind flow to add to the lift it is generating so its lift angle into the wind would need to be quite shallow to avoid generating too much lift and creating a roll effect. The retreating blade on the other hand has 300km/h reverse wind so it needs to be angled up significantly to compensate and balance the lift being generated by the attacking blade on the other side of the helicopter. The faster you fly the worse it becomes and the speed limit is dictated by the retreating blade stall... where the retreating blade is angled up so high to generate life moving backwards through the airflow that essentially it is no longer generating lift and instead is just batting the air and creating drag... the helicopter will then roll over to that side and crash...

    Improved blade tips and reduced weight blades, might increase speed by allowing higher forward speeds without stalls...

    Perhaps even being able to drop the nose to the level that instead of acting like free spinning wings like on a gyrocopter, the blades instead provide direct thrust like the propeller on the nose of an aircraft where all blades are essentially pulling evenly through the incoming air flow even higher speeds can be attained...

    Of course with Coaxial designed rotors retreating blade stall is not a problem because with two sets of rotors there are always two blades going forwards and two going back...

    LMFS
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    Post  LMFS Thu Aug 27, 2020 4:39 pm

    GarryB wrote:Improved blade tips and reduced weight blades, might increase speed by allowing higher forward speeds without stalls...

    I think these blade tips address the problem of the tips going transonic at high forward speeds, which is additional to that of the retreating blade you comment. That is why it will only provide a short term mitigating effect or small speed increase, bigger increases in speed will demand newer approaches.
    GarryB
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    Post  GarryB Fri Aug 28, 2020 8:41 am

    It is like the squeak you hear in your car... you search and search and eventually you find what is making it and you fix it... but once that squeak is gone you then start hearing the next noise that you didn't notice when you had the squeak but this will annoy you even more because you were expecting silence.

    I doubt a fix to blade tips will transform the speed of a helicopter... who knows how much it limited speed, but most helicopter blades are constant speed rotation so flight speed shouldn't have that much effect on them... they don't speed up or slow down the rotation rate... they change the pitch angle of the blades to change lift or flight speed of the aircraft.

    When they upgraded the Hind using parts developed for the Havoc they said the rotor was made 300kgs lighter and the blades were 20-30% more efficient and generated so many kgs more lift... so this change should further improve things without burning more fuel or making more noise or making it expensive.

    The angled wings on the high speed model are not that much different from the old wings from the Hind which were high lift angled designs too... they said when they upgraded them to the more stubby modern ones that replicate those on the Havoc that it would reduce the amount of weight off loaded from the main rotor during forward flight, which was not so good, but it also improve lift performance in the hover which it spend rather more time doing at near max weights so they decided it was worth it.

    The reduced sized wing also allowed the older Ataka and Shturm missiles to be carried in bundles of 8 per outer pylon so with the new wing it could carry 16 ATGMs and two rocket pods or gun pods... which is rather better than the old Hind which had a total of four ATGMs on the wing tips and then twin ATGMs on each under wing pylons or rocket pods underwing for either four ATGMs and four rocket pods or 12 ATGMs or 8 ATGMs and two rocket pods...

    flamming_python
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    Post  flamming_python Fri Aug 28, 2020 5:16 pm

    Serial production of the updated Mi-35P has begun

    Russian Helicopters holding company (part of rostec state Corporation) has started mass production of Mi-35P combat helicopters in an updated appearance under an export contract at Rostvertol, the Corporation's press service reported on Sunday.
    "Last year, we demonstrated this machine to a number of potential customers and today we can say with confidence that the helicopter is in demand – today, serial production of the Mi-35P has begun under the first contract signed with a foreign customer," TASS reports Andrey Boginsky, CEO of the holding.
    the Mil and Rostvertol design bureaus upgraded the Mi-24 attack helicopter under the working name Mi-35P+. The helicopter received an analog-digital complex for guided missiles, which were not previously used on this type of helicopter. Also, there are optical-electronic system.

    Shame they don't name the customer
    Perhaps Venezuela
    LMFS
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    Post  LMFS Fri Aug 28, 2020 6:06 pm

    GarryB wrote:I doubt a fix to blade tips will transform the speed of a helicopter... who knows how much it limited speed, but most helicopter blades are constant speed rotation so flight speed shouldn't have that much effect on them... they don't speed up or slow down the rotation rate... they change the pitch angle of the blades to change lift or flight speed of the aircraft.

    I seem to remember a speed increase between 10-15% for existing models being mentioned. Since it comes apparently without downsides it is a very nice improvement.
    magnumcromagnon
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    Post  magnumcromagnon Mon Nov 23, 2020 5:49 pm

    This is the deadliest looking Christmas Tree, Rave Party, helicopter I've ever seen! Shocked
    Mi-24/35M Hinds: News - Page 7 Em71llzW4AAwZez?format=jpg&name=medium

    Don't remember Tron looking like this? Wink

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    mnztr

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    Post  mnztr Fri Dec 04, 2020 6:05 am

    GarryB wrote:

    I doubt a fix to blade tips will transform the speed of a helicopter... who knows how much it limited speed, but most helicopter blades are constant speed rotation so flight speed shouldn't have that much effect on them... they don't speed up or slow down the rotation rate... they change the pitch angle of the blades to change lift or flight speed of the aircraft.


    what do you think happens to the speed of the blades as the helo picks up speed? Blades are not only pitched but tilted. The blade tip speed reachs critical as its travelling the fastest AND slowest as the helo speeds up.
    Cheetah
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    Post  Cheetah Wed Dec 09, 2020 2:51 am

    mnztr wrote:what do you think happens to the speed of the blades as the helo picks up speed?

    Rotor RPM is relatively constant in helicopters. There are instruments in the cockpit to inform the pilot about just that. In Russian helicopters, it's usually represented as a percentage, where the normal zone of operation is typically between 85-98%. Any lower and the AC generators trip, any higher and the mechanism is experiencing over-speed.

    It becomes a different story if you're talking about rotor speed relative to the surrounding air, which is when you make reference to the leading and trailing hemispheres of the rotors, and can get into topics like rotor stalls and the like, which is what the major limiters are when talking about absolute helicopter speed. Changes to the rotor tips will change how the air acts around them, quite possibly postponing the point of rotor stall for a few 10s of km/h. Who knows.


    magnumcromagnon wrote:Don't remember Tron looking like this? Wink

    Yes, getting back to the tron hind, does anyone know what that angular pyramid device is? The one between the cockpit and the crew compartment? My guess is that it's part of the DIRCM; MAWS camera, perhaps.
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    Post  mnztr Wed Dec 09, 2020 3:27 am

    Ergo the focus on the aerodynamic treatment of the rotor tips...
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    Post  Cheetah Wed Dec 09, 2020 9:57 am

    I could be misreading your last message, but you seemed to suggest that something happened to the rotor speed as the speed of the helicopter increased (as per the part I quoted). I was merely stating that was not the case. In a short, direct answer to your possibly rhetorical question "what do you think happens to the speed of the blades as the helo picks up speed?"

    the answer is 'very little' if you're meaning relative to the helicopter, which I assumed you were. If you meant absolute speed, relative to the air, then skip the next paragraph.

    The rotor speed remains constant (more or less) regardless of the helicopter's speed. 10km/h, 100km/h, 300km/h, doesn't matter; The rotors are still spinning at approximately the same rate. The tricky part is that, at some point, the speed of the helicopter inversely matches that of the retreating rotors, so to a bystander the rotors on the retreating side (more specifically the outboard portion of the rotors) would appear stationary. Which means they are generating no lift; so, suddenly, a good portion of the retreating side of the rotor disk is dead-weight and the helicopter rolls and pitches.

    Retreating rotor stalls will happen regardless of the collective setting or the rotor tilt, though the former is a large contributing factor to how severe the stall is. Generally speaking, the only factors that determine how fast the actual helicopter can go before a stall are the rotor diameter and rotor RPM, which for obvious reasons will already be pretty close to the best compromise according to physics.

    It would be interesting to know how a redesign of the tip changes the stall speed, even if only by a little.
    GarryB
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    Post  GarryB Thu Dec 10, 2020 2:19 am

    I would suggest that rotor tip changes wont effect the rotor speed at all, and any increase in flight speed will always be limited by retreating blade stall limits... but just as wing fences improve the performance of swept wings by minimising spanwise airflow, I would think improved tip design also improves lift right to the rotor tip which being the outer edge of the rotor arc is an enormous volume of space.

    When talking about circles when you increase the radius by 1/3 you triple the volume of space the new circle has... so if you make the outer third of the rotor blade more efficient and increase its lift you can dramatically improve the performance of the rotor.

    Wings are good for speed because they generate lift so the rotor does not, which means less engine power is needed to keep the aircraft at that speed and height.

    No wings and the lift has to come from the rotors which means greater angle of attack and therefore more power for the stroke.

    If you think of a Kayaker... a flat paddle requires the most strength to pull through the water but gives you the best thrust forward... turn it 90 degrees and the paddle will slice through the water like a knife... literally... it will take very little energy so you could do it faster and much longer than a normal stroke, but it will barely make the boat move... the differences in angle of the blade is the same in both cases.... when sitting on the ground with the blades spinning you don't want any lift but you don't also want to be running the engines hard so in engine idle the blades are knifing through the air... when you want to take off you turn the blades and as they bite into the air you get lift... obviously if you flatten their angle to the angle a kayaker uses you will start pushing air outwards instead of down... you will be well into blade stall territory and while you engine will be running hard you will also be dropping like a rock because you are not creating lift.

    Unlike a Kayaker the rotor blades on a helicopter never get to more than 60-70 degrees angle of attack or they don't create lift...

    Yes, getting back to the tron hind, does anyone know what that angular pyramid device is? The one between the cockpit and the crew compartment? My guess is that it's part of the DIRCM; MAWS camera, perhaps.

    That is the position for a previous early warning device that detected incoming threats... part of an old system was oval and had a womans name... nadia or something.
    magnumcromagnon
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    Post  magnumcromagnon Thu Dec 17, 2020 10:52 pm

    Imagine the Gsh-30K shredding through the Apache's window glass which isn't even capable of stopping 7.62x39mm! Twisted Evil
    #Syria #Russia #USA
    #Mi_35 running into a AH-64 #Apache over Northern Syria

    Mi-24/35M Hinds: News - Page 7 EpZJsroUwAEi0zw?format=jpg&name=900x900

    https://twitter.com/Cyberspec1/status/1339338983424212992
    Werewolf
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    Post  Werewolf Fri Dec 18, 2020 1:35 am

    magnumcromagnon wrote:Imagine the Gsh-30K shredding through the Apache's window glass which isn't even capable of stopping 7.62x39mm! Twisted Evil
    #Syria #Russia #USA
    #Mi_35 running into a AH-64 #Apache over Northern Syria

    Mi-24/35M Hinds: News - Page 7 EpZJsroUwAEi0zw?format=jpg&name=900x900

    https://twitter.com/Cyberspec1/status/1339338983424212992

    I am pretty sure it would shredd it in midair with a few nice hits.

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    GarryB
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    Post  GarryB Fri Dec 18, 2020 8:39 am

    Even the chin mounted twin barrel 23mm cannon on the newer Hinds would be devastating due to their rate of fire and projectile weight...
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    Post  thegopnik Sun Dec 27, 2020 7:09 pm

    Video tribute of the Mi-35

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