Tandem & Tilt-Rotor Aircraft development

The main problem with the American tiltrotor is the size of the blades which limits the speed of the blades and therefore also the top speed of the aircraft.

This Russian drone appears to use much smaller propellers which can all operate in forward flight allowing higher flight speeds to be achieved... but drone sized things don't always scale up very well so we will have to see.

I still think high speed helicopter designs have more promise and of course conventional aircraft will always out perform helicopters in speed and range and flight efficiency.

Sometimes all those planes need is some sort of all weather undercarriage like a hovercraft to take off from dirt or grass or water or sand or snow or any large flat area.

Not as good as landing on a small spot but most of the time good enough and much cheaper than a tiltrotor or helicopter alternative.

but the Tu-95 props r huge, their tips have supersonic speed, & it's the fastest prop driven plane in the world.

They are huge but they are slim and very specifically designed for high speed.

Compare the long slim blades of the Tu-95 with the multiple blades on the D-27 on the An-70.

In terms of thrust the D-27 generates more thrust but is unable to accelerate the An-70 to a speed faster than an Il-76 let alone the Tu-95.

The shape and profile of the blades on the V22 as well as the shape and profile of the V22 aircraft mean it will never be a high speed contender compared with conventional aircraft in the same role.

The blades on the V22 are 11 metres across... another 3.5 metres in width and they are the same size as the main rotors of the Hokum.

The blades on the Tu-95 are about 5.6 metres across and the reason the Bear flies rather faster than western assessments thought it would is because it has constant speed propellers that are subsonic.

Supersonic blade tips would make the engines less efficient, and the simple fact that the current Bears are still the worlds fastest propeller driven aircraft in the world suggests maximum efficiency.

Considering their length the Tus blades are long and slim and not fat and flat like the much larger V22s rotor blades.





To repeat the AV-60T blades on the new Tu-95s are constant speed propellers... increasing the throttle or decreasing the throttle just changes the pitch of the blades and not their rotational speed.

If they were supersonic blade tips then the noise the aircraft would make would be like a Harvard trainer (T-6) or a UH-1 Huey helicopter under load (during takeoff).

The Tu-95 has very powerful engines that cause noise but no supersonic blade issues.

The new AV-60T blades reduce vibration by 50% which actually makes them rather quieter.

So, it may be that the US can't produce such powerful engines for their props?

Propeller aircraft have a specific niche these days in the role of light short range transport that does not need to fly fast and to operate from short rough airstrips, so developing new more powerful turboprop engines to get flight performance equivalent to a jet makes little or no sense for the US.

For Russia having the Bear, which has better flight range than the B-52 and is actually faster at lower altitudes when sneaking in to attack, it makes sense to continue to improve the aircraft design because no level of extra power will make it supersonic but its range and near sonic speed over an enormous flight range makes it more difficult to intercept than it would otherwise be.

Of course it will be replaced by the PAK DA in good time, but transport planes using propellers are not in great demand because they are slower even if they are more fuel efficient and operate better at lower altitudes.

Still, the An-70 has higher cruise speed: 466 mph

Cruise speed is not top speed, and the figures supplied in the links you gave show the cruise speed is 750km/h but top speed is 780km/h, which is not much faster for the An-70, while the cruise speed for the Bear is given as 710km/h, but the Bears top speed is significantly faster at 925km/h.

If the blades used on the An-70 would improve the speed of the Bear they would use them... they are of Russian design and manufacture.

Which suggests they are not suited to going faster than the Bear is capable of flying.

The Chinese tiltrotor appears to have the advantage of being small enough that the engines and blades are closer to the size of conventional turboprop propellers, which means in turboprop mode they should be able to be as fast as a normal turboprop aircraft, but its performance in vertical takeoff is the question...

It is not in serial production and might not even fly yet.

BTW... the Pentagon has found the problem with the Osprey... is it that its design is dogshit... which is also why they wont say what the problem is because they need to sell more to cover their costs?

Not operationally suitable... a clever way of saying they are dogshit.

The US is better off without those missile magnets.

The twin engined aircraft look like a dog balancing on a unicycle... it really looks unbalanced and unsafe.

The V44 with four engines in twin tandem arrangement actually looks better to me... but the problem of the enormous blades remain.

Being able to take off vertically is nice but it really only makes sense with super small super light platforms because when you scale it up to a good size the down wash and enormous footprint start to make it a real negative.

I think the better solution is short range vertical takeoff platforms that can pick things up from anywhere and then carry them at reasonable speed (even helicopter speeds) to a nearby airfield where you can put people and cargo on much bigger much more efficient much faster and much longer ranged conventional aircraft.

I would say the combination of Ka-226s or Ka-60s or Mi-17s or Mi-38s to go and pick up people and cargo and fly to a nearby airfield and then transfer to an upgraded An-2 or Baikal or Il-212 or Il-114 and then fly conventionally but at much higher speed a few thousand kms to another airfield where the cargo and passengers can be distributed to other platforms and sent on their way makes more sense than a tiltrotor that costs 100 million dollars per aircraft... may not be particularly safe (which means enormous insurance costs) .

The idea is not new and from a theoretical point of view is interesting... we see all sorts of spaceships in science fiction with various rotating engines.... but it is easy when you are faking everything and super powerful engines directing their fhrust into the ground a few metres from your aircraft... which creates your own dust storm that isn't pleasant and not good for air intakes or just breathing either.

I think VSTOL aircraft might be more practical with the introduction of electric jet engines and thrust vectoring nozzles... a Yak-141 with the two lift engines moved from tandem behind the cockpit to side by side and extended out of the fuselage of the aircraft, with that enormous R79M engine it had in the back providing electrical power with the front lift engines able to rotate in their mounts to provide both vertical and horizontal, but the key is that they all have full 3D thrust vectoring nozzles so that in the hover the thrust lines and directions can be adjusted to manouver the aircraft in takeoff and landing.

You could also have the main rear engine operating with an 85 degree downward deflection so it has a 5 degree rearward angle rather than straight down so the hot gas from the engine exhaust does not go forward towards the air intake, and to balance that the two lift engines can be angled 5 degrees forward to counter that effect, but electric engines are just fans so the airflow should not be hot and nor should it be oxygen depleted like the airflow through a conventional jet engine where fuel is burned to create the thrust.

With electric drive fans the airflow should be oxygen rich and so it hitting the ground and deflecting up into the main air intakes would not be a problem.

You could even be clever and design it so the front lift engines are fixed and in vertical take off they provide lift but in forward flight they could accelerate the air going into the main jet engines bypass region so they sort of supercharge the airflow in the normal turbofan engine.


(Note in a normal turbofan engine a turbojet engine drives a big fan on the front of the drive shaft to suck air around the outside of the turbojet to add a huge volume of air going through the engine... it is oxygen rich and also cold and dense so it means you can dump more fuel into the afterburner and get more thrust from the after burner than you can with a turbojet... having a turbofan engine with two electric jet engines feeding airflow through its bypass air section should improve thrust and efficiency of the engine while making use of otherwise not very useful lift jets...)

Just an idea... all just my opinion and you don't have to agree.

The problem with multirole is when it is not as good in either role.

A V22 that is super expensive and unreliable to the point where it is described as operationally unsuitable is not a good thing.

A helicopter and a light aircraft can do the job and other jobs at the same time... the new composite An-2 replacement made by that Siberian group with a new Russian engine is not going to cost more than 2-3 million dollars, and a decent light helicopter like a Ka226 is not going to cost much more, but the V22 is well over 70 million per aircraft... you could buy 20 An-2s and 20 Ka-226s and operate them for 20 years and it still wont cost 70million.

From a private companies perspective you can't recover that sort of outlay because you still need to pay for fuel and insurance and support with parts and equipment not being cheap either... it is simply not practical for civilian use.

It is no accident that the C-141 was not widely sold to private companies, yet the rather similar Il-76 was very very popular and widely used.

These days military forces in the west or western friendly countries operate C-17s but private companies simply cannot afford such aircraft.

The V22 is the C-17/F-35... even the European transport A-400M is just too expensive to operate privately... they are just being super greedy.

the USAF needed all of them until their time was up, but if they were offered with at least 50% life left & at reduced prices, some civ. operators would've bought them.

If anyone actually wanted them there has been plenty of time for more to be made and as they were replaced by C-17s there would be used aircraft that could be bought and used if it made commercial sense...

if they & A-400Ms r offered later as a surplus & at burgain prices, some private companies may buy them.

They are simply too expensive to operate let alone buy... you could get four or five Il-476s for the price of an A-400M or C-17, and the operational costs would be more expensive for the western aircraft too, so the profit margin would be thin or simply not enough to take the risk.

Personally I think the factories that claim they are ready to make more An-124s should be making Il-476s instead and also a few Il-276 prototypes for development and serial production in the next few years. A factory that could make either will be a licence to print money soon because C-130 and C-141 class aircraft have proven useful and a jet powered An-12 and an Il-76 that can carry 50% more than the original could over a greater distance with new engines that are more fuel efficient and more reliable just makes a lot of sense... and the fact that the factories will be set up paid for by Russian military orders means civilian models and export military orders will be piling up pretty soon.

Many used DC-3s, C-130s, An-8/12s & large Vietnam War era transport helos were sold to them before. There's a Y-20 variant for civ. use:

They did because they were cheap and reliable and solid... put new engines on a DC-3 and it still works just fine... as long as it is in good condition and not with too many hours on the airframe.

It is why the An-2 was so popular and lasted so long after concerted repeated attempts to replace it.

Meanwhile, the ongoing struggles of the Russian aerospace industry in the face of international sanctions could even see a civilian Y-20B fill the niche currently filled by the Il-76, especially for commercial chartered airlift.

That is very true, but the biggest word there is could.

Having a civilian version available with Chinese-made engines would be a major boost for potential operators.

Does China have a reputation for good reliable and fuel efficient engines?

Tiltrotors made outside the West will be a lot cheaper to make & operate; as their price goes down, private owners will find good uses for them, even if other aircraft r cheaper to buy & operate individually.

We only see prototypes and the US stopping using the V-22 will hurt the idea too.

Just my own personal opinion I would think two gas turbine engines mounted centrally on the fuselage with the rotor blades on the wing tips being spun by electric motors running from electrical current from the gas turbines might be safer... maybe with a nose mounted rotor too and a rear mounted main wing... perhaps.

true, esp. if there weren't new & converted freight versions of DC-10 & B-747/757/767s widely available!

And yet at the same time those aircraft were available other countries bought Il-76s... the direct equivalent of the C-141.

The C-141 didn't need to be commercially viable as a civilian aircraft to be a military aircraft, and the C-17 is actually worse in terms of cost performance ratio... they are just not designed for commercial use... which makes perfect sense because they are military aircraft and only military forces can afford them.

the wait times for Il-476s would be longer & many operators may get sanctioned for getting them, besides constant political constrains on using Russian made planes. The An-70 has better specs & could be produced under licence but the A-400M was chosen instead.

They are taking steps to ramp up production of the Il-476 and if they take the decision (or they have already taken the decision) to go for the Il-276 to replace the An-12 then progress in that department can be expected too because the same factories that make Il-276s could also make Il-476s if needed and vice versa so the potential to make a couple more factories that can make Il-476s till there are enough to meet Russian and international demand while the Il-276s are being tested and prepared for serial production, and then some of those factories can shift to making Il-276s to replace the An-12s.

Of course they are also serial producing Tu-214s so the Tu-330 which is a 35 ton payload transport based on the Tu-214 would make sense too, so increase the number of factories making the Tu-214 to get them out faster while you develop the Tu-330 and then shift to production of the Tu-330 when that is ready.

The Tu-214 factories can then shift to converting them to military use to replace the Il-20/22 and Tu-154M and Yaks and Il-38s and other old types still in use.

not yet, but those re-engined Y-20Bs will help to establish it!

That is not how it works. If you are a commercial operator you don't risk an unknown plane with unknown engines to be the core of your business... no one is going to fund that business and no bank will offer the loans you would need to get started.

Even if everything they promised was true, you would need your own international support network to keep those engines running anywhere, and of course you might find their engines need a very high standard type fuel and you make your best profit on old Il-76s burning the cheap fuel.

how about a quad rotor? bigger craft will need more engines.

I agree, a quad rotor design would be more balanced... and if the electric motors that drive the blades can be articulated in 3D would be even more useful.

I don't mean complete 3D rotation, they would not need to do a full circle on the end of the wing, and they wont need to do more than maybe 15 degrees left and right, but being able to angle the thrust vertically for takeoff and landing and forward to fly normally and backward to rapidly slow down, but also angle the blades left and right 15 degrees each way would give a level of manoeuvrability that would make the aircraft safer in tight spaces and better able to land in a specific place on the ground.

In a Harrier jump jet or a Yak-141 they had puffer jets in the tail and the wing tips and in the nose to allow them to manouver better in the hover when the wing and tail surfaces provided no control because there was no air flow over them.

Having 3D thrust vectoring nozzles would mean they don't need high pressure air from the engine to feed high pressure air to these locations, which makes the design simpler and cheaper and lighter and less prone to battle damage.

It would also give the flight control system more control and ability to manouver... and also trim the aircraft in flight to improve aerodynamics by reducing drag.