Tandem & Tilt-Rotor Aircraft development

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.

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.

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.

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.

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...

A high speed helicopter makes rather more sense in every regard than wasting money on tiltrotor designs.

Not really... smaller diameter rotors means higher speed to support the weight, so a smaller volume of air holding the aircraft up which means it has to be moving faster to support the aircrafts weight.

The Mi-26 has a powerful down wash because at max weight the thing weighs almost 60 tons.

A quad copter with the same capacity... which does not exist BTW would have just as much downwash to remain airborne.

The reality is that the combination of helicopters and fixed wing aircraft make rather more sense... if you want range and speed a conventional aircraft is vastly better than any alternative, while helicopters are generally rather useful for certain things it is not the end of the world that they are not great at speed and flight range...

hey Garryb. might be a stupid question but could you cant the blades slightly upward and lengthen the blades of a helicopter to create more lift?

You can't increase the performance of an existing helicopter by increasing the angle of the blades simply because they already do that to change the lift generated by the blades in flight.

When the helicopter is hovering the blades just go round and round so they all travel at the same speed and generate the same amount of lift so the helicopter remains in the air and level.

When the helicopter moves forward the blades on one side of the main rotor disk are moving forward into the oncoming airflow while the blades on the other side are moving with the oncoming airflow... the flight speed of the helicopter is deducted from the retreating blades and added to the advancing blades... if all the blades remained at the same angle the helicopter would roll over because one side has more lift than the other.

To compensate the retreating blades are angled up to generate more lift while the lift angle on the advancing blades might be reduced to balance the lift of both sides to keep the helo level.

Having a helicopter design that already has angled blades to increase the lift it generates would limit its top speed...

One limit on a helicopters forward speed is called a retreating blade stall where you are travelling forward so fast the blade cannot be angled up high enough to generate lift and instead creates drag, and you get a retreating blade stall which will roll the helicopter over and likely cause a crash.

The V-22B can fly faster & above the weather while hauling more cargo than the IL-112 ; it's comparable with An-132 payload & speed & C-295M payload, range & speed .

So what? The V-22B is unlikely to be safer than an Il-112, and certainly would never be cheaper either.... the V-22B is 72 million dollars an aircraft... that is ridiculous... you could buy two Su-30s for that price...

If we superimpose the map of Indonesia on the maps of Russian Arctic & the FE, the advantage of having tiltrotors becomes clear. Russian models will be at least 10-15% larger & more capable to make it even more feasible.
Therefore, it's better to have a combination of fixed/rotary wings that includes hybrids of the 2 as well.

The 35 billion dollars it has taken the US to develop these tilt rotor craft just makes it clearly not worth the effort...

Russia is already spending money developing high speed helicopters... it is more useful to build airfields than to use expensive accident prone odd vehicles to get around...

They are looking at high speed trains that travel at 600km/h...