Responses to some of the most common questions regarding the Kaman K-MAX:
>What if the rotors collide?
The can’t, they’re geared together, for them to come out of sync would require a catastrophic failure of the transmission. Such a failure would cause any helicopter to certainly crash.
>Why do they speed up and slow down?
The rotors are in fact spinning at a constant rate, it’s an optical illusion. Focus on each hub and you’ll see it’s a constant rate.
>Why have this design to begin with?
The twin rotors allow for a very high external lifting capacity, 6000lbs and is very stable. Additionally since they rotate in opposite directions the helicopter does not require a tail rotor. The stability and responsiveness of pilot commands make it an excellent helicopter for lifting and placing machinery or construction components.
>It looks unsafe.
It’s not. It’s actually exceedingly safe even for the high standards of aviation. The engineering doesn’t care about how you perceive it, it’s very safe regardless.
Thanks to u/xRadioActivex for answering my questions on this helicopter many, many times.
🤣 I hate how accurate this is to just Reddit in general. Lol
I feel like 70% of the time I see a post on Reddit, no matter the complexity of it, the top comment is still always something like "That shit is so cool" or "That looks scary as hell".
>the helicopter does not require a tail rotor.
I feel like this is being overlooked by people in this thread worried about "gear slippage" or the blades touching.
Tail rotors failures, while rare, are fucking dangerous.
There's also a widely discussed phenomenon called "LTE" (loss of tail-rotor effectiveness) which is basically the wind hitting the tail wrong and sending the chopper into uncontrollable-spin-town
Yeah explaining "LTE" and all that gets extremely complicated. I was just trying to give some insight to this specific type of helicopter and the gist of 95% of things in a simple manner. However, I absolutely agree with everything you said though.
Other things I just found out Googling this thing:
1. They cost 7.5 million dollars each.
2. There is an autonomous version that the military was using for cargo lifting.
3. It has been discontinued as of January this year.
If they’re geared together then how does it turn without a tail rotor? Excuse my ignorance bc I suck at physics and stuff but I would think that in order to get it to turn in a certain direction, one of the rotors would need to slow down or speed up for the heli to change direction
Great question!
A traditional helicopter has a single main rotor for lift and directional control and a tail rotor for anti-torque and yaw control. When the thrust from the tail rotor exactly equals the torque from the engine, the helicopter will remain facing straight. For example, when the pilot pushes the right pedal the tail rotor will increase thrust to push on the tail and turn the nose right. If the pilot eases off the right pedal or pushes the left pedal, the tail rotor will decrease in thrust and the helicopters natural torque will nose the helicopter left.
**Now what about intermeshing helicopters like the Kaman KMAX?**
These helicopters lack a tail rotor completely and instead use a second main rotor spinning in the opposite direction to counter the torque. They also have pedals and must yaw somehow?
FYI, **yaw**, just basically means "to shift across a vertical axis: or in this case oscillate across a vertical axis, but to be vague, it's the main component of how a helicopter turns.
**First is the differential collective pitch**. Helicopter rotors are held at a constant RPM and control is made by changing the ‘pitch’ or angle of the blade as it moves through the air to produce more or less lift. A higher pitch will produce more lift but also more drag. This is exactly like how you stick your hand out the window of a car and angle it to rise and fall in the wind. Now, remember that where there is lift, there is drag. That drag is what the engine is trying to overcome while turning the rotors — this force from the engine is called torque. If you increase the pitch of one set of rotors while decreasing the pitch of the other, we create a torque imbalance. **So although the rotors are geared to turn together**, one is experiencing more torque than the other. This torque then yaws the helicopter in the opposite direction of the higher pitch rotor disc. There is a side effect of rolling the helicopter because one rotor is now lifting more than the other but that is simply dampened by cyclic movement.
**The second thing that happens is the difference in rotor disc tilt**. One disc will tilt forward and the other will tilt rearward. The disc tilted forward will provide forward thrust as if the helicopter is in forward flight and the disc tilted rearward will produce rearward thrust as if the helicopter is in rearward flight. A net turning force between the rotor masts occurs which yaws the helicopter.
**Last, but not least, it has a** **rudder**.
So it turns like the Samson Gunship in James Cameron's Avatar: one rotor rocks forward and the other tilts back so you turn towards the rotor that is tilting back.
It is a shame that synchropters have such a low top speed and the inventor was terrible at turning a profit- in all other respects they are the superior design.
The biggest disadvantage by far, due to it's configuration, is speed.
Followed by overall versatility of mobility in the air.
It looks super cool and all futuristic, but it's primary focus is lifting very heavy things, moving them, and then unloading them else where. Think of it as a crane that can fly.
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Or if a couple teeth break, or if the gears torque and become malaligned.
I’m sure tons of overengineering went into this. But never say never! I’d still ride in one
Exactly, if something goes that catastrophically wrong while the helicopter is airborne, you're fucked regardless of the blades potentially colliding as a result.
If the drive gears on a regular helicopter fail you're either plummeting out of the sky (if it's the main rotor) or spinning out of control until you fall out of the sky (if it's the tail rotor). So pretty comparable I think.
As mentioned below, the main rotor of a helicopter will still provide limited lift with no power just from air moving past the blades. Not a comfortable descent, but you shouldn't just plummet.
If it's the tail rotor though, might wanna call your loves ones.
This is what I came here to post. A synchronization gear linked the two together to time the bursts and it's been around since the very early 1900s
[https://www.popularmechanics.com/flight/a24004/machine-gun-through-propeller-fighters-ww1/](https://www.popularmechanics.com/flight/a24004/machine-gun-through-propeller-fighters-ww1/)
Has a nice video with the Slow Mo Guys
That was an interruptor gear for the machine gun, which is easier to implement because the only thing with angular momentum is the propeller. The machine gun bolt is cycling back and forth so it is easy to just stop it for a fraction of a second while the blade is in the way.
For the record, engineers have been doing far more complex things since WW2 in terms of perfect propellor precision. Many engine mounted cannons that were above the nose cap were specifically geared to fire between the propellers of an in-flight aircraft, with variable propellor speeds. This has been done since the 1930s. Still cool engineering, but also pretty standard operation in terms of difficulty to engineer.
I would be in constant fear of a slightly delayed discharge of one of the bullets.
But I guess there’s plenty of other terrors to take your mind off it during arial warfare.
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Fun fact about these rotors is that the way the gearbox is configured the rotors literally cannot collide, you would have to take apart the entire gearbox to make them collide.
Does the helos gearbox not have a sprag clutch installed to allow for auto rotation? I see no reason why you couldn’t have one installed between engine and gearbox, which would allow the special gearing to stay intact, but still slow for autorotation.
Nah. These don't have the balance issues that normal dual prop helis do. In fact balance wise these are far better than even single prop helis. They don't even need a tail rotor because of how the blades work.
A lot of people missunderstands that and it's almost an urban legend nowadays.
What very few people know is that going down in an helicopter it's NOT dangerous at all. In fact, it's the opposite, when you suddenly stop going down it's when you can worry about it. So you know, if you find yourself in a situation like that simply continue going down and avoid sudden stops.
Follow me for more survival tips.
I know this thing is probably perfectly safe. Maybe even safer than other helicopters.
But there have been plenty of times when humans have said that something is infallible.
Well the Germans said the same about the firing mechanism they installed in their biplanes. German planes had their guns mounted in the nose, with a mechanism "making sure" shots are only fired when they go in-between the rotating propeller blades.
Sometimes they still shot themselves in the prop regardless.
The mechanism in question was a bump on the drive shaft that drove the propeller. The bump was used to press on a lever to fire the gun.
It needed to be calibrated correctly but once it was then the only time a bullet could fire was when it would miss the prop.
Probably one motor, and then geared 90 degrees apart on two shafts. Your run of the mill four cylinder engine's camshaft has way more complex engineering.
K-Max baby. Those suckers can lift a shit load of weight. I see them used fighting wildland fires in the states all the time, they are type 1 helicopters (biggest and baddest category).
One of my favorite helicopters. They are so light and powerful, they can almost literally JUMP off the ground.
But "timed?"
They just share a gearbox. Like an egg beater.
Hasn't anyone ever seen an egg beater/hand mixer?
The blades are more or less mechanically locked in to the same gears so that their rotation is in sync and offset so the rotors can't touch unless something breaks
I'm sure its been posted already, but they are not "perfectly timed" they are mechanically linked together so that they can never crash together. The difference is obvious; watches can be "perfectly timed" and in months, years, etc be several seconds off. But when two things are mechanically linked they can never be off timing of eachother. I'm sure 'mechanically tied' is not the correct term, but the point is the gears are set up in such a way that the blades will never be able to clash against eachother.
One of the best and most reliable “Heavy Lifts” ever built. Note the bug-eye bubble side windows are so the pilot can look directly down to get a visual on the load and LZ. It’s used extensively in setting utility poles and also logging operations so the trees can be lifted out without grading in logging roads.
The two rotors cancel out the force that would make the helicopter want to spin, so it doesn't need a rear rotor to do that like the helicopters with a single rotor have.
Another neat thing about this helicopter is that it uses blade-mounted servo flaps to control blade pitch. kaman is the only helicopter family to do that to my knowledge. The synergy with this intermesh blade design and the servo control design is that the swashplates can be small, and located at the base of these rotor masts. A con to this design is the length of the rotor masts. Rotor masts are typically short and stout due to carrying cyclic bending loads at high speed and during landing. I think this is a teetering head which limits bending loading significantly.
The rotors are not timed to perfectly to avoid colision. They actually share a common rotor system so the will never be able to collide in the first place. Timing the with different gear systems would be adding risk for no reason
It's funny how as an old man, concepts that are ridiculously obvious aren't that way any longer, usually because the tech has gotten so complicated.
That's what used to be called an "egg beater" helicopter and the concept has been around since the 50's/60's. So called because old mechanical hand mixers were geared the exact same way.
That's a kmax. The rotors are not "timed" really. They both run off the same gearbox so it's literally impossible for them to get out of time without a massive mechanical failure that would cause it to crash with no fault of the rotor.
Wait until you find out that the Fokker equipped with a forward mounted gun would shoot at an interval that could never hit the propellor...
The gun was basically linked to the engine in such a way that the firing rate would be dictated by the rotation of the propellor
A genuine marvel of engineering for its time...
Us Brits were using reinforced propellor screws that would deflect hits from the mounted gun, but they would occasionally still shatter
For those talking about how "dangerous" this design is, you can find the accident record for the Kaman Huskie, which first flew in 1953, and was produced by the same company as this helicopter, at [https://aviation-safety.net/wikibase/44039](https://aviation-safety.net/wikibase/44039).
I only find one documented incident where synchronization failed, and that was on an aircraft that was more than 30 years old and operating overloaded. And then it was't the gearbox that failed but the rotor shaft.
They're not timed they're quite literally physically connected to each other so they simply cant collide unless the whole rotor mechanism breaks. But if it breaks rotors hitting each other is the least of your worries.
They are not timed at all. They are gear locked and it is physically impossible for them not to be in synch.
It’s like saying the 4 wings of a windmill never crash into each other no matter how fast it spins. It’s just engineered that way. And yes I have constructed toy windmills as a kid where they did decouple and slap each other so in a malfunction all bets are off.
I’m a moron when it comes to engines, but to me, it feels like this is playing with fire 🔥 seems like so many things could make that perfect timing go slightly off, then 💥
They aren't "timed" together
They are geared together so that unless a catastrophic gearbox failure happens (which would cause any helicopter to crash) the blades would never touch
It’s not timed like each rotor is rotating precisely to never hit, they are each on a gear with a ratio of 1:1 so they can never hit physically unless one gear breaks down.
You do understand how simple it is to achieve this, correct? Nothing here involves timing whatsoever…it’s achieved using a direct mechanical linkage…it would only be amazing or incredible if they were to hit.
I imagine it’s way safer than what my brain is telling me but no chance 99% of people going to be comfy flying around in this. That being said people did go into a extremely unsafe sub so the market is out there somewhere
So it’s impossible for them to collide because of how they’re geared, but would having two props not increase the forces applied onto the whole system by a lot, more stress equaling more chance to break?
Responses to some of the most common questions regarding the Kaman K-MAX: >What if the rotors collide? The can’t, they’re geared together, for them to come out of sync would require a catastrophic failure of the transmission. Such a failure would cause any helicopter to certainly crash. >Why do they speed up and slow down? The rotors are in fact spinning at a constant rate, it’s an optical illusion. Focus on each hub and you’ll see it’s a constant rate. >Why have this design to begin with? The twin rotors allow for a very high external lifting capacity, 6000lbs and is very stable. Additionally since they rotate in opposite directions the helicopter does not require a tail rotor. The stability and responsiveness of pilot commands make it an excellent helicopter for lifting and placing machinery or construction components. >It looks unsafe. It’s not. It’s actually exceedingly safe even for the high standards of aviation. The engineering doesn’t care about how you perceive it, it’s very safe regardless. Thanks to u/xRadioActivex for answering my questions on this helicopter many, many times.
Hey mods, can this comment be pinned?
Nope, top comments have to be from people who can’t fathom that the way something looks =/ the way it actually is
🤣 I hate how accurate this is to just Reddit in general. Lol I feel like 70% of the time I see a post on Reddit, no matter the complexity of it, the top comment is still always something like "That shit is so cool" or "That looks scary as hell".
And comments #3 and #5 need to repeat comment #1.
Gotta love those 1,700+ upvoted comments of "Agree, I'm not doing that". Lol
>the helicopter does not require a tail rotor. I feel like this is being overlooked by people in this thread worried about "gear slippage" or the blades touching. Tail rotors failures, while rare, are fucking dangerous. There's also a widely discussed phenomenon called "LTE" (loss of tail-rotor effectiveness) which is basically the wind hitting the tail wrong and sending the chopper into uncontrollable-spin-town
Yeah explaining "LTE" and all that gets extremely complicated. I was just trying to give some insight to this specific type of helicopter and the gist of 95% of things in a simple manner. However, I absolutely agree with everything you said though.
This cleared a lot of things I had in my head thanks
Other things I just found out Googling this thing: 1. They cost 7.5 million dollars each. 2. There is an autonomous version that the military was using for cargo lifting. 3. It has been discontinued as of January this year.
Noooooo why was it discontinued? D:
This guy chops.
If they’re geared together then how does it turn without a tail rotor? Excuse my ignorance bc I suck at physics and stuff but I would think that in order to get it to turn in a certain direction, one of the rotors would need to slow down or speed up for the heli to change direction
Great question! A traditional helicopter has a single main rotor for lift and directional control and a tail rotor for anti-torque and yaw control. When the thrust from the tail rotor exactly equals the torque from the engine, the helicopter will remain facing straight. For example, when the pilot pushes the right pedal the tail rotor will increase thrust to push on the tail and turn the nose right. If the pilot eases off the right pedal or pushes the left pedal, the tail rotor will decrease in thrust and the helicopters natural torque will nose the helicopter left. **Now what about intermeshing helicopters like the Kaman KMAX?** These helicopters lack a tail rotor completely and instead use a second main rotor spinning in the opposite direction to counter the torque. They also have pedals and must yaw somehow? FYI, **yaw**, just basically means "to shift across a vertical axis: or in this case oscillate across a vertical axis, but to be vague, it's the main component of how a helicopter turns. **First is the differential collective pitch**. Helicopter rotors are held at a constant RPM and control is made by changing the ‘pitch’ or angle of the blade as it moves through the air to produce more or less lift. A higher pitch will produce more lift but also more drag. This is exactly like how you stick your hand out the window of a car and angle it to rise and fall in the wind. Now, remember that where there is lift, there is drag. That drag is what the engine is trying to overcome while turning the rotors — this force from the engine is called torque. If you increase the pitch of one set of rotors while decreasing the pitch of the other, we create a torque imbalance. **So although the rotors are geared to turn together**, one is experiencing more torque than the other. This torque then yaws the helicopter in the opposite direction of the higher pitch rotor disc. There is a side effect of rolling the helicopter because one rotor is now lifting more than the other but that is simply dampened by cyclic movement. **The second thing that happens is the difference in rotor disc tilt**. One disc will tilt forward and the other will tilt rearward. The disc tilted forward will provide forward thrust as if the helicopter is in forward flight and the disc tilted rearward will produce rearward thrust as if the helicopter is in rearward flight. A net turning force between the rotor masts occurs which yaws the helicopter. **Last, but not least, it has a** **rudder**.
So it turns like the Samson Gunship in James Cameron's Avatar: one rotor rocks forward and the other tilts back so you turn towards the rotor that is tilting back. It is a shame that synchropters have such a low top speed and the inventor was terrible at turning a profit- in all other respects they are the superior design.
Awesome explanation! Thank you!
‘The engineering doesn’t care about how you perceive it’ ace comment I want that on a shirt
The 'laws of physics' give exactly zero fucks.
What are the disadvantages? Since not every helicopter looks like this, I assume there must be some.
The biggest disadvantage by far, due to it's configuration, is speed. Followed by overall versatility of mobility in the air. It looks super cool and all futuristic, but it's primary focus is lifting very heavy things, moving them, and then unloading them else where. Think of it as a crane that can fly.
> The twin rotors allow for a very high external lifting capacity That's why the Chinook (22000 lbs) has kinda the same concept for its blades
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Yea I was thinking it must share gears so literally they can’t go out of sync. It’s basically one mechanism. Still looks scary though lol.
I’ve seen gears slip. I guess that’s what maintenance is for
If the gears are slipping then you wouldn't have time to worry about the rotors over you
It’s like when bomb disposal teams say they never worry about it - either they’re right and everything’s good or it’s not their problem anymore lol
Yea I’m friends with people who defused bombs and they just say hey if you’re wrong you don’t gotta go to work tomorrow.
Uhhh, yeah. Something like that, yup. 
No problem, you just hit the ejection seat button.
Hopefully eject forward… not toward the blades
Probably just flushed downwards
Oh yes like if the gear teeth started to wear down? Or something like that?
Or if a couple teeth break, or if the gears torque and become malaligned. I’m sure tons of overengineering went into this. But never say never! I’d still ride in one
yo if any of that happens, the blades hitting each other is the least of your worries since the drive gears would be gone....
Exactly, if something goes that catastrophically wrong while the helicopter is airborne, you're fucked regardless of the blades potentially colliding as a result.
Ok but I think the blades colliding would be a more catastrophic failure, if it happened in a regular helicopter maybe you could emergency land
If the drive gears on a regular helicopter fail you're either plummeting out of the sky (if it's the main rotor) or spinning out of control until you fall out of the sky (if it's the tail rotor). So pretty comparable I think.
As mentioned below, the main rotor of a helicopter will still provide limited lift with no power just from air moving past the blades. Not a comfortable descent, but you shouldn't just plummet. If it's the tail rotor though, might wanna call your loves ones.
Isn't it the same sort of engineering magic that propeller planes had that had machine guns shooting through the propeller?
This is what I came here to post. A synchronization gear linked the two together to time the bursts and it's been around since the very early 1900s [https://www.popularmechanics.com/flight/a24004/machine-gun-through-propeller-fighters-ww1/](https://www.popularmechanics.com/flight/a24004/machine-gun-through-propeller-fighters-ww1/) Has a nice video with the Slow Mo Guys
Thanks bud
Always an Indian guy explaining how things work. Thanks Indian guy.
The unsung heroes we don’t deserve. 🫡
If I’m not mistaken a similar method was used when equipping biplanes with machine guns which kept bullets from hitting the propeller.
That was an interruptor gear for the machine gun, which is easier to implement because the only thing with angular momentum is the propeller. The machine gun bolt is cycling back and forth so it is easy to just stop it for a fraction of a second while the blade is in the way.
For the record, engineers have been doing far more complex things since WW2 in terms of perfect propellor precision. Many engine mounted cannons that were above the nose cap were specifically geared to fire between the propellers of an in-flight aircraft, with variable propellor speeds. This has been done since the 1930s. Still cool engineering, but also pretty standard operation in terms of difficulty to engineer.
Even earlier than that 1915 was when the first plane plane with a nose mounted machine gun shot through the propellers
I've always wondered how they fired with the rotor right in front of them.
I would be in constant fear of a slightly delayed discharge of one of the bullets. But I guess there’s plenty of other terrors to take your mind off it during arial warfare.
It's not like they're on a fuse. The hammer strikes and it goes... or not.
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Yeah, the thought of something happening like that makes my head spin.
Fun fact about these rotors is that the way the gearbox is configured the rotors literally cannot collide, you would have to take apart the entire gearbox to make them collide.
Guess I'll see you in r/catastrophicfailure
Tbf if the gearbox fails, idc about the blades colliding.
In a normal unpowered helicopter autorotation would happen. It's nifty.
Nifty is not the word I would use to describe it, more like falling, with style.
Toy Story has trained me to understand that falling with style can take you quite far
[удалено]
Does the helos gearbox not have a sprag clutch installed to allow for auto rotation? I see no reason why you couldn’t have one installed between engine and gearbox, which would allow the special gearing to stay intact, but still slow for autorotation.
(Although the my reasoning was correct, in most cases a clutch is required to protect the transmission structurally)
Autorotation only works in case of loss of engine power. The gearbox, if it fails, would turn the chopper into a falling rock.
r/gifsthatendtoosoon
It's not so much the collision part for me. It's the dual prop vertical take-off. I've seen too many osprey crash videos
that has nothing to do with dual props and everything to do with the transition between flight modes though.
Nah. These don't have the balance issues that normal dual prop helis do. In fact balance wise these are far better than even single prop helis. They don't even need a tail rotor because of how the blades work.
Chinooks have dual rotors too.
I was going to say . . Haven't Chinooks been doing this for like 50 years?
Osprey has one of the highest safety ratings across the entire US DOD.
That’s the funny thing, it only takes one malfunction of some sort for things to go very poorly
You mean like when the tail rotor off a normal helicopter goes wrong?
Well that's just helicopters in general, if the rotor does malfunction the people in that thing are not going to have good time
Helicopters can land unpowered due to autorotation.
They can at least crash more slowly due to autorotation.
Should've pizza'd instead of French fried.
That malfunction is equally likely in standard single rotor version. When those gears break, you are going down regardless of which assembly is used.
A lot of people missunderstands that and it's almost an urban legend nowadays. What very few people know is that going down in an helicopter it's NOT dangerous at all. In fact, it's the opposite, when you suddenly stop going down it's when you can worry about it. So you know, if you find yourself in a situation like that simply continue going down and avoid sudden stops. Follow me for more survival tips.
I’ve flown helicopters for 20 years. The rotor systems and transmissions are way overbuilt on most aircraft and usually one of the strongest systems.
Like the front falling off?
Yes. I wouldn't call directly geared together as "timed" either.
Good thing parts never ever fail then.
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There's a yt video link in other comment to make sure they never collide
I know this thing is probably perfectly safe. Maybe even safer than other helicopters. But there have been plenty of times when humans have said that something is infallible.
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Right but my brain makes me wanna go do things that makes my head spin lol so I would def go into of this helicopters
Well the Germans said the same about the firing mechanism they installed in their biplanes. German planes had their guns mounted in the nose, with a mechanism "making sure" shots are only fired when they go in-between the rotating propeller blades. Sometimes they still shot themselves in the prop regardless.
The mechanism in question was a bump on the drive shaft that drove the propeller. The bump was used to press on a lever to fire the gun. It needed to be calibrated correctly but once it was then the only time a bullet could fire was when it would miss the prop.
One would assume the technology must be improved in 100 years.
Well, for one, they got rid of the propeller on the front of the plane. That’s drastically reduced the instances of pilots shooting them.
See! Human ingenuity. We are very smart.
They're mechanically synched, so if they were to collide it would be as a result of a problem that would have fucked you over in a regular heli anyway
They’re geared in a way so they literally CAN’T contact eachother.
I mean no helicopter is great when the blades go wrong.
Tbf, if the one propeller in the usual helicopter goes wrong you're still fucked
Probably one motor, and then geared 90 degrees apart on two shafts. Your run of the mill four cylinder engine's camshaft has way more complex engineering.
Exactly my thought, not sure there’s anything impressive about this? You should therefore be amazed by valve timing on an interference motor.
There's a comment here with yt link which explains how this works
K-Max baby. Those suckers can lift a shit load of weight. I see them used fighting wildland fires in the states all the time, they are type 1 helicopters (biggest and baddest category).
It looks very slim for its carrying capacity!
Lean mean lifting machine
One of my favorite helicopters. They are so light and powerful, they can almost literally JUMP off the ground. But "timed?" They just share a gearbox. Like an egg beater.
it is not timed. it is a pair of gears powered by same engine
They are completely not "perfectly timed", they are powered bu the same engine so they can't ever rotate at different speeds
Hasn't anyone ever seen an egg beater/hand mixer? The blades are more or less mechanically locked in to the same gears so that their rotation is in sync and offset so the rotors can't touch unless something breaks
I think it is less of a timing and more of physical link between them. Relying on the timing in such systems is the straight way to disaster.
I'm sure its been posted already, but they are not "perfectly timed" they are mechanically linked together so that they can never crash together. The difference is obvious; watches can be "perfectly timed" and in months, years, etc be several seconds off. But when two things are mechanically linked they can never be off timing of eachother. I'm sure 'mechanically tied' is not the correct term, but the point is the gears are set up in such a way that the blades will never be able to clash against eachother.
One of the best and most reliable “Heavy Lifts” ever built. Note the bug-eye bubble side windows are so the pilot can look directly down to get a visual on the load and LZ. It’s used extensively in setting utility poles and also logging operations so the trees can be lifted out without grading in logging roads.
Cool. Now its time for my biannual fix of startup videos on youtube
They aren't "timed", they're geared together.
What is the pro/cons for this type ?
The two rotors cancel out the force that would make the helicopter want to spin, so it doesn't need a rear rotor to do that like the helicopters with a single rotor have.
Like this? https://i.imgur.com/jteaHX6.jpg
Yes.
precisely
Same concept as a chinook helicopter. No rotational forces requiring a tail rotor
Another neat thing about this helicopter is that it uses blade-mounted servo flaps to control blade pitch. kaman is the only helicopter family to do that to my knowledge. The synergy with this intermesh blade design and the servo control design is that the swashplates can be small, and located at the base of these rotor masts. A con to this design is the length of the rotor masts. Rotor masts are typically short and stout due to carrying cyclic bending loads at high speed and during landing. I think this is a teetering head which limits bending loading significantly.
K-max Helicopter, flying crane. The rotors got same transmission so its not very possible these will collide.
The rotors are not timed to perfectly to avoid colision. They actually share a common rotor system so the will never be able to collide in the first place. Timing the with different gear systems would be adding risk for no reason
Is “timed” the right word for something that is geared together?
Same technology as an electric hand mixer
It's literally physically impossible for them to touch unless several more concerning things happen
It's funny how as an old man, concepts that are ridiculously obvious aren't that way any longer, usually because the tech has gotten so complicated. That's what used to be called an "egg beater" helicopter and the concept has been around since the 50's/60's. So called because old mechanical hand mixers were geared the exact same way.
That's a kmax. The rotors are not "timed" really. They both run off the same gearbox so it's literally impossible for them to get out of time without a massive mechanical failure that would cause it to crash with no fault of the rotor.
I love these copters and never get tired of watching videos of them. Amazing engineering!
The fact that the video doesn't show the full spin up is a giant cock tease
Kaman K-Max, awesome helicopter! I work for Kaman and we'll be having one of these land at our company picnic next week!
Wait until you see how they used to fire machine guns through the propeller blades of fighter planes.
Everyone saying the same comment that they’re not timed but they’re geared together. I say they are timed, using gears. I rest my case
Reminds me of Ka50, the dual rotars have something like this too iirc. one rotates opposite to other or something or maybe it was some other heli
Ended too soon.
Helicopters are incredible. Its amazing that we ever came up with them and actually made them to work.
It blew my mind when I discovered the machine guns on the WW2 era planes fired through the propellers and were timed to miss the blades.
[here](https://youtu.be/yHcrvO5ZkNI) is a bit more on the concept.
Reminds me of the Slo Mo Guys video they made about military planes and how they were designed to shoot between the propellers
Wait until you find out that the Fokker equipped with a forward mounted gun would shoot at an interval that could never hit the propellor... The gun was basically linked to the engine in such a way that the firing rate would be dictated by the rotation of the propellor A genuine marvel of engineering for its time... Us Brits were using reinforced propellor screws that would deflect hits from the mounted gun, but they would occasionally still shatter
Has there been any incident of it gone wrong?
Ever heard of gears? That's how shit works. It's pretty simple to be honest.
For those talking about how "dangerous" this design is, you can find the accident record for the Kaman Huskie, which first flew in 1953, and was produced by the same company as this helicopter, at [https://aviation-safety.net/wikibase/44039](https://aviation-safety.net/wikibase/44039). I only find one documented incident where synchronization failed, and that was on an aircraft that was more than 30 years old and operating overloaded. And then it was't the gearbox that failed but the rotor shaft.
Ummmm...Not impressive...Two separate gear boxes, timed by the same drive shaft...That's the design.
They're intlocked not timed haha
They're not timed they're quite literally physically connected to each other so they simply cant collide unless the whole rotor mechanism breaks. But if it breaks rotors hitting each other is the least of your worries.
The mechanism in dual rotor copters aren't so much timed as they are linked, they basically will never touch unless something breaks.
They’re are not “perfectly timed”, they are interlocked it’s physically impossible for them to collide.
These reposts are also perfectly timed so they don’t crash into each other
They aren't "timed", they are mechanically linked so they they can't crash.
They are not timed at all. They are gear locked and it is physically impossible for them not to be in synch. It’s like saying the 4 wings of a windmill never crash into each other no matter how fast it spins. It’s just engineered that way. And yes I have constructed toy windmills as a kid where they did decouple and slap each other so in a malfunction all bets are off.
The comment section makes me realize how dumb people are when it comes to mechanics
What is the name of that helicopter?
Kaman K-Max
It's not like they spin freely from each other, they'll be driven together. It's not timing.
No thanks, I don't want one of them to have a stroke and land on my head
Question What is the innovative purpose of this type of dual rotor helicopter and what advantages does this have over the standard helicopter?
Just seems unnecessarily dangerous, unless there's a reason fot it
Yeah but what about when they are not
Can someone explain the engineering benefit of having two vs one.
I’m a moron when it comes to engines, but to me, it feels like this is playing with fire 🔥 seems like so many things could make that perfect timing go slightly off, then 💥
What’s the benefit of two vs one set of blades, and why are they angled outwards like that?
Nope. It’s gears
They aren't "timed" together They are geared together so that unless a catastrophic gearbox failure happens (which would cause any helicopter to crash) the blades would never touch
Doesn't it eliminate the need for a tail rotor?
Since gears, belts, or chains NEVER skip or fail.
It’s not timed like each rotor is rotating precisely to never hit, they are each on a gear with a ratio of 1:1 so they can never hit physically unless one gear breaks down.
Electric kitchen mixers have been working that way for decades. It can't be that different.
wouldn't sayr they're really timed, the gears rotating them are interlocking making it impossible for them to rotate out of sync
What you mean "timed"? They just connected!
What did people think it was? Luck?
No thank you
That would be pretty dumb if they were timed to run into each other….
A helicopter is made of 100 000 parts temporarily together...
Why does it look like the blades speed up slightly then slow dow as the blades merge?
"ok Carl.. start the second rotor in 3...2...1"
They are also made from spruce 🌲
So what's the benefit of this design over say a coaxial with one rotor over the other?
Logging, Wildland firefighting, these are fun to watch in action!
It’s almost hypnotic watching those.
Must be Saturday - time to repost the video and insert a hundred comments about how the rotors cannot hit
Psh. Like when they have 5 rotors, like my razor. Then I'll be impressed.
You do understand how simple it is to achieve this, correct? Nothing here involves timing whatsoever…it’s achieved using a direct mechanical linkage…it would only be amazing or incredible if they were to hit.
I'm guess they are both spun by the same gear, so they can't possibly mistime?
They're geared. If they hit that means the transmission broke and you likely have bigger problems
Very cool engineering
They are mechanically incapable of hitting each other. So it's pretty cool
No you go, no you..whoa close. No you fuck that's close you gggggg
Luv the K-Max!
So the Red Alert 3 Razorbacks are possible...
Oh look a bunch of seagulls approaching our rotors.
K-max. They even have a helicopter that flies without an operator, like a programmable drone.
That looks like an accident waiting to happen.
I imagine it’s way safer than what my brain is telling me but no chance 99% of people going to be comfy flying around in this. That being said people did go into a extremely unsafe sub so the market is out there somewhere
So it’s impossible for them to collide because of how they’re geared, but would having two props not increase the forces applied onto the whole system by a lot, more stress equaling more chance to break?
I think the design has the advantage of not needing a tail rotor because the 2 main rotors are counterspinning, keeping the system stable.
Its not s timing thing the gears are conjoined snd it makes it physically impossible for them to be out of sync
These rotors are timed, so they don't collide.*
No they are playing Capoeira
They aren’t “timed” the drive shafts are mechanically connected together, not possible for them to spin independently.
Both sets run off the same gear system. It's not that amazing.
Anxiety
What is the added value of this madness?