Comments on: Sikorsky 'progressing' with X2 helicopter effort

Aircraft maker is showing off the unusual design, which someday, it says, will cruise twice as fast as today's helicopters.

[bob1xxxx]

Cool

[myles taylor]

I would love to fly in this thing. It looks beautiful. Honestly, I don't know why the dual rotor hasn't become more common. It was used in the 70s in a very ugly machine but the concept works. Even in WWII the it was known that rotors operating in opposite directions canceled each other out and made for a quieter engine.

[byl01]

Contra-rotating propellers increase efficiency - the Russian Tu-95 bomber (in production since the '50s) uses them. However, one thing these propellers do NOT do is reduce noise - just the opposite. According to some reports, the antisubmarine version of the Tu-95 could actually be heard inside the submarines (submerged!) it was supposed to hunt.

[ralfthedog]

Would dual rotors increase mechanical complexity? Would compression waves from the top rotor cause stress to the bottom?

[NervClaX]

Even if the chopper was loud enough to be heard by the submarine, what could a sub do at that point to avoid being hit? The sub is slow to dive and get up to speed. Everyone on board would have just enough time to crap themselves before being blown out of the water.

[SactoGuy018]

If they can double the speed of the helicopter, this could make it very viable for business flying in the US Northeast, where the distance between large population centers are much shorter. It would essentially become the first viable alternative to the commercial tiltrotor helicopter that Bell and Augusta are developing--and possibly at much lower cost, too.

[ralfthedog]

And it would reduce the annoying bit about crashing on VTOL transition.

[twburger]

New experimental design my sweet aunt Fanny! It's a copy of a Russian design: The Ka-25 Hormone from 1961. I saw a smaller prototype version at the Abbotsford Airshow in 1989. It's a good thing the RIAA doesn't own rights to aircraft designs, Sikorsky would have it's corporate tail chewed off.

http://en.wikipedia.org/wiki/Kamov_Ka-25

[myles taylor]

I don't think the new design is the double rotor. As I stated in my comment, a dual rotor is not a new idea. The design is the entire machine and if you look at the Russian chopper it's nothing like this one.

[capnvan]

While the Ka-25 is a significantly older design, the Ka-50 is similar, lacking only the pusher propeller. It also uses the contra-rotating dual rotors.

Its maximum speed? 205 knots. First flight? 1982. Sikorsky isn't leading the field - it's playing catch-up.

[mbenedict]

Get real people. Comparing the Ka-25 or KA-50 to the X2 just non-sense.

The KA-50 has a cruising speed of just 146 kts. That's SLOWER than the UH-60 Blackhawk, a mere transporter with a 150 kts cruising speed. The X2 will cruise at 250+ kts.

And sorry, "lacking only the pusher propeller" is a totally ignorant comment. The whole point of the X2 is to demonstrate high-speed gyrodynes. Google "compound helicopter" and be informed. Hint: the Kamovs are NOT compound helicopters, they are co-axials.

[RussianBear2]

They are about 10 years behind. Russians not only developed this technology but already supplied first 20 to the army. http://www.enemyforces.net/helicopters/ka52.htm
Look for Ka52 or "Alligator: Helicopter
By the matter of fact they already have 2nd generation of this helicopter in production.

[mbenedict]

Um, no. The Ka-52 is not a compound helicopter, just a co-axial. Huge difference.

[ejschlapp]

Lockheed's AH-56 Cheyenne attack helicopter implemented the pusher propeller in a single rotor design back in the 60's so that idea isn't new either. This may be the first time that a pusher prop is married to a coaxial rotor.

http://en.wikipedia.org/wiki/AH-56_Cheyenne

[holyhope]

Nice design, contra rotation. It could be much quieter on intrusion compared to a Huey, but probably not as quiet or as fast as the v-22, which relies for lift on the wing, which is not going to disturb the air as much as a propellor at any rate because of lower loading per square foot.

[byl01]

... except V-22 is about as reliable as a Ford Pinto.

[ralfthedog]

byl01, Yes, the V-22 does crash on VTOL transition like a XBOX 360 in July with the AC turned off.

[bob1xxxx]

v 22 = death , its unarmed a death trap on a good day and a class case of criminal congressional pork barrel spending on a bad day.

[SergeM256]

Of course it is not a new design, this design in has been around for decades. I don't think it is even possible to invent a new design, looks like all possible designs have been tested in 30's and 50's. We may see some old designs being re-invented when modern material and technologies make them more practical. X2 is only prototype/model with intended speed of 250 knots but nobody could tell how it will work when it will be actually build. Russian Ka helicopters are mostly designed and optimized for Navy and high speed is not the highest priority for the tasks they were designed for.

[bob1xxxx]

Yes the kamov kh 25 and 50 etc.... were originally design for ship based for asw /over the horizon missile targeting helio's with out the dangerous tail rotor which cause most small ship helio casualities (ie destoryers and crusiers). The two counter rotating main rotors cancel out the gyroscopic effect single main rotor causes, and yes while their more complex than single main rotors there far less complicated and far more reliable and safer to operate than osprey style tilt rotor designs. Yes the pusher comes form the old Lockheed Cheyenne , plus now Sikorsky can use new metals and material (ie graphite, nomex, polmyers, composites) which did exsist in the late 1960 and 1970's so they do have a good chance of building a faster helio. But I doubt you'll ever see a heilo faster than 280mph due to supersonic rotor tip shockwaves for rotor blades as the approach the speed of should. Still a very Cool developmental concept design and good place to start for faster and safer helios.

[gdmaclew]

Would you please learn how to spell "they're".

[bob1xxxx]

And dual rotors are not new the us helicopter company Kaman http://www.kamanaero.com/helicopters/kmax.html uses two counter rotating inter meshing rotors to cancel out the gyroscopic effect of the main rotors . There current production helio is the K max use for helio crane and water drop work. Kamam first dual intermeshing rotor design was the US Airforce kamam huskie http://www.aviastar.org/helicopters_eng/kaman_huskie.php. So duel rotors on helios has been around for a very very long time

[hudmack]

High forward speed is the objective. To do this a rotor must be as rigid as possible and co-axial (One above the other turning in opposite directions) . This helps to reduce retreating blade stall at higher speeds. The pusher prop at the rear adds to forward speed and enables the main rotor to have less angle of attack which also helps to reduce blade stall at high forward speed. The rigid rotor tends to transfer differentials of lift from one set of blades to the other to balance opposing forces. All these things require advanced design in order to get a few more mph from a helicopter. Looks simple but it is not so easy to do. If this Sikorsky goes into production it will be quite an accomplishment.

[bob1xxxx]

Yeah thanks , you spelled out what I was trying to say more clearly, and yes if Sikorsky is successful it would be a great engineering feat and very Cool to boot