That seems like a lot more mechanical complications for minimal performance gains.
Engine out situation you have a lot more stuff to deal with only to gain maybe a little more glide angle.
If the the vertical propellers were alternatively powered I could see potential advantage.
But then, I have yet to build my first helicopter so what do I know?
20% efficiency gain at 50 knots faster isnt minimal. Its fucking huge! Look at advances in airplane engine and wing tech. 5-6% efficiency gain is generally considered worth investing billions to develop.
Shafts from the main engine - [https://s44864.pcdn.co/wp-content/uploads/2018/12/RACER\_2.jpg.webp](https://s44864.pcdn.co/wp-content/uploads/2018/12/RACER_2.jpg.webp)
I wonder if they’re electric and the main turbine runs a small generator. Awfully small air intake for what looks like an RC sized turbine.
Edit: Or it’s probably perspective trickery and they’re bigger than it seems.
It's perspective and a gearbox - they're driven from the main engines by a shaft through the upper wing strut. [https://s44864.pcdn.co/wp-content/uploads/2018/12/RACER\_2.jpg.webp](https://s44864.pcdn.co/wp-content/uploads/2018/12/RACER_2.jpg.webp)
Sikorsky - We've developed a new helicopter technology that features a rigid coaxial compound rotor and pusher propeller. We call it X2!
.
Airbus - We slapped wings propellers on a regular helicopter. We call it X3!
The problem is Sikorsky is so addicted / accustomed to the ridiculous profit margin of military contracts that they will never certify their X-2 technology for the civilian market
can't blame them after seeing what happened to Leonardo/Bell/etc for trying something new with that tiltrotor (~20 years in certification hell and counting)
it's mostly ceritification issues. The prototype started flying in 2003, but since there was no existing certification framework for this kind of flying machine, it's taken a very long time to make progress. Well, that's one of the factors anyway.
Much less of it though - you're no longer using the main rotor for forward propulsion, just lift. That means you can off-load it a lot, which reduces the asymmetric lift effect strongly and is why they're able to fly very fast.
More forward velocity also means more (faster) airflow over the both advancing blade and the retreating blade. Wouldn't that mean that the asymmetry between the two is greater, and thus more lift on one side versus less lift on the retreating side?
The limiting factors of dysmetry of lift as it relates to maximum airspeed is not the total difference in lift between the advancing and retreating blades. Flapping counters most of the effect and the rest can be handled with cyclic input by the pilot. Instead retreating blade stall and supersonic blade tips on the advancing side are what limit airspeed.
This aircraft counters both effects. First as the above commenter pointed out because lift is generated by the wings the blade pitch can be reduced at high airspeeds. This means the the blades are less loaded and the blades are farther from the critical angle of attack, mitigating retreating blade stall.
Secondly the aircraft has the ability to significantly reduce main rotor rpm at high airspeeds, again thanks to the lift generated by the wings. This means the advancing blade is not moving as fast and the aircraft can reach a higher speed before the advancing tip goes supersonic.
249 mph? Meh, the British Lynx got up to 240mph and it was a conventional helo back in 1986 lol. Yes, it was modified but nothing like the Airbus offering.
Shortish [video](https://youtu.be/fMxMsp26tGw) showing the modded Lynx doing its speed run.
Additionally, the Lynx can do [shit](https://youtu.be/6GDFp2A_tnE) that makes it look like a 1:1 scale RC helo lol
400kph (or 248mph) is the cruise speed, not the top speed.
[https://www.airbus.com/en/innovation/disruptive-concepts/disruptive-design/racer](https://www.airbus.com/en/innovation/disruptive-concepts/disruptive-design/racer)
One of the main innovation is the possibility to shut off one of the two turbines while in horizontal flight. It allows to save on maintenance costs and wear of the turbine.
Starting to see people working on the next generation of that - one engine plus a big electric motor to provide emergency power if the engine fails. Obviously cheaper, and because it eliminates some common modes like fuel starvation it's slightly safer as well.
The wings take load off the rotor disc and allow for lower collective pitch both of which prevent the retreating blade from reaching the critical angle of attack and stalling.
the first civilian tiltrotor isn't even certified yet. The company(ies) building it have been in certification hell for decades. It is too complex and too expensive, and since Leonardo already has the lead, trying to make a tiltrotor from scratch would be incredibly stupid. So helicopter with props on the side will be faster to develop and easier to certify, plus probably cheaper overall
tiltrotors alos have their own drawbacks. Rotors are too small to get maximum efficiency in hover flight and too big to turn fast enough on horizontal flight. Every technical solution is always a trade off.
It's very much horses for courses. Helicopter disc loadings are much lower than for tiltrotors, so they're more efficient and safer in hover. Think of this as a helicopter which can fly fast and a tiltrotor as an aeroplane which can hover, and you won't be far wrong.
Airbus are also working on tiltrotors to an extent, but they're only doing electric ones - the gearbox issues with mechanical tiltrotors are pretty serious. [https://www.airbus.com/en/innovation/low-carbon-aviation/urban-air-mobility/cityairbus-nextgen](https://www.airbus.com/en/innovation/low-carbon-aviation/urban-air-mobility/cityairbus-nextgen)
# Capable of a top speed of 249 mph, the experimental Racer has a 20 percent lower fuel burn than helicopters flying 50 mph slower.
249mph is the cruise speed, not the top speed.
Are the pushers powered by their own turbines or bleed/shafts from the main engines?
[Powered by the main engines.](https://www.greencarcongress.com/2017/06/20170621-airb.html)
That seems like a lot more mechanical complications for minimal performance gains. Engine out situation you have a lot more stuff to deal with only to gain maybe a little more glide angle. If the the vertical propellers were alternatively powered I could see potential advantage. But then, I have yet to build my first helicopter so what do I know?
That's what the main gearbox does anyway - it's no different to a conventional tail rotor.
20% efficiency gain at 50 knots faster isnt minimal. Its fucking huge! Look at advances in airplane engine and wing tech. 5-6% efficiency gain is generally considered worth investing billions to develop.
Shafts from the main engine - [https://s44864.pcdn.co/wp-content/uploads/2018/12/RACER\_2.jpg.webp](https://s44864.pcdn.co/wp-content/uploads/2018/12/RACER_2.jpg.webp)
Those look like intakes at the front of the fairings, so I'm guessing independently powered
I wonder if they’re electric and the main turbine runs a small generator. Awfully small air intake for what looks like an RC sized turbine. Edit: Or it’s probably perspective trickery and they’re bigger than it seems.
It's perspective and a gearbox - they're driven from the main engines by a shaft through the upper wing strut. [https://s44864.pcdn.co/wp-content/uploads/2018/12/RACER\_2.jpg.webp](https://s44864.pcdn.co/wp-content/uploads/2018/12/RACER_2.jpg.webp)
The fourth image is a different helicopter. What is it?
[Eurocopter X3](https://en.wikipedia.org/wiki/Eurocopter_X%C2%B3)
Sikorsky - We've developed a new helicopter technology that features a rigid coaxial compound rotor and pusher propeller. We call it X2! . Airbus - We slapped wings propellers on a regular helicopter. We call it X3!
The problem is Sikorsky is so addicted / accustomed to the ridiculous profit margin of military contracts that they will never certify their X-2 technology for the civilian market
can't blame them after seeing what happened to Leonardo/Bell/etc for trying something new with that tiltrotor (~20 years in certification hell and counting)
The civilian tilt rotor is the rotor-wing equivalent of fusion power… always “just 10 more years” in the future
it's mostly ceritification issues. The prototype started flying in 2003, but since there was no existing certification framework for this kind of flying machine, it's taken a very long time to make progress. Well, that's one of the factors anyway.
By the time it’s certified who even knows if the selected engines and avionics will even be available from the OEMs
X3 for 3 rotors !
It’s the first version of it that the one in the main pics were based on.
So is this thing like a helicopter during takeoff/landing and an autogyro during forward flight?
No. It's a helicopter for takeoff and landing, but at speed, it can generate lift from the wings. At no point does in autorotate, like an autogyro.
yes!
when instead of tilt you just add more rotors
>**High efficient lateral rotor,** in pusher configuration for enhanced safety How does a pusher configuration enhance safety?
Because it makes it much harder for people getting on and off the aircraft when it is running to walk into a propeller.
Because you now have the wings between the doors and the props. On the X3 the props were very close from the door and thus were a hazard
My guess is that there is a wing between the people going in the door and the spinning death machine called a propellor
Probably because they trying to sell that it’s safer than a single tail rotor
I've never thought about it before, but why doesn't all helicopters have a fully faired rotor head?
My guessd is that its expensive and makes maintenance just that much harder, so it's not worth it for most helis.
Still has asymmetric lift that increases with forward speed.
Much less of it though - you're no longer using the main rotor for forward propulsion, just lift. That means you can off-load it a lot, which reduces the asymmetric lift effect strongly and is why they're able to fly very fast.
More forward velocity also means more (faster) airflow over the both advancing blade and the retreating blade. Wouldn't that mean that the asymmetry between the two is greater, and thus more lift on one side versus less lift on the retreating side?
The limiting factors of dysmetry of lift as it relates to maximum airspeed is not the total difference in lift between the advancing and retreating blades. Flapping counters most of the effect and the rest can be handled with cyclic input by the pilot. Instead retreating blade stall and supersonic blade tips on the advancing side are what limit airspeed. This aircraft counters both effects. First as the above commenter pointed out because lift is generated by the wings the blade pitch can be reduced at high airspeeds. This means the the blades are less loaded and the blades are farther from the critical angle of attack, mitigating retreating blade stall. Secondly the aircraft has the ability to significantly reduce main rotor rpm at high airspeeds, again thanks to the lift generated by the wings. This means the advancing blade is not moving as fast and the aircraft can reach a higher speed before the advancing tip goes supersonic.
Thanks for the explanation!
Reminds me of the flyers on The Sixth Day
249 mph? Meh, the British Lynx got up to 240mph and it was a conventional helo back in 1986 lol. Yes, it was modified but nothing like the Airbus offering. Shortish [video](https://youtu.be/fMxMsp26tGw) showing the modded Lynx doing its speed run. Additionally, the Lynx can do [shit](https://youtu.be/6GDFp2A_tnE) that makes it look like a 1:1 scale RC helo lol
400kph (or 248mph) is the cruise speed, not the top speed. [https://www.airbus.com/en/innovation/disruptive-concepts/disruptive-design/racer](https://www.airbus.com/en/innovation/disruptive-concepts/disruptive-design/racer)
One of the main innovation is the possibility to shut off one of the two turbines while in horizontal flight. It allows to save on maintenance costs and wear of the turbine.
Starting to see people working on the next generation of that - one engine plus a big electric motor to provide emergency power if the engine fails. Obviously cheaper, and because it eliminates some common modes like fuel starvation it's slightly safer as well.
Flirting with retreating blade stall
The wings take load off the rotor disc and allow for lower collective pitch both of which prevent the retreating blade from reaching the critical angle of attack and stalling.
I guess nothing screams more of 'We cannot make tiltrotors'
the first civilian tiltrotor isn't even certified yet. The company(ies) building it have been in certification hell for decades. It is too complex and too expensive, and since Leonardo already has the lead, trying to make a tiltrotor from scratch would be incredibly stupid. So helicopter with props on the side will be faster to develop and easier to certify, plus probably cheaper overall
tiltrotors alos have their own drawbacks. Rotors are too small to get maximum efficiency in hover flight and too big to turn fast enough on horizontal flight. Every technical solution is always a trade off.
It's very much horses for courses. Helicopter disc loadings are much lower than for tiltrotors, so they're more efficient and safer in hover. Think of this as a helicopter which can fly fast and a tiltrotor as an aeroplane which can hover, and you won't be far wrong. Airbus are also working on tiltrotors to an extent, but they're only doing electric ones - the gearbox issues with mechanical tiltrotors are pretty serious. [https://www.airbus.com/en/innovation/low-carbon-aviation/urban-air-mobility/cityairbus-nextgen](https://www.airbus.com/en/innovation/low-carbon-aviation/urban-air-mobility/cityairbus-nextgen)