Piasecki first developed the ducted tail rotor in the 1950's. At that time (if memory serves) they made a helicopter that topped 200 mph (we're talking the 1950's so that's an impressive speed). Fast forward to today and the US Army is looking for a future rotorcraft that flies faster and higher.
So why isn't the Speed Hawk getting a serious look?
The retrofit to legacy helicopters would be simple and if weight reduction was conducted then you'd see standard helos approaching 350+ mph.
Solutions are readily available to the requirements that the military puts out. Everything that we desire today has been on the Pentagon wish list going back to WW2. Maybe we should dust off the work that was done by our forefathers with slide rules and use our advanced tech to make their dreams and our needs come true.
We did it with the Orion Spacecraft (call it big Apollo) and we can do it with the SpeedHawk.
I believe I read something where the issue of "retreating blade stall" limits the birds to under 250kts, but I could be wrong, my degree is in economics. I think a British Lynx, was the only single rotor craft to achieve this speed.
ReplyDeleteyeah, mine is history but i'm still not sure on this one....i believe that the piasceki xh-59 or something like that broken 250 in the 50's....the ducted fan and the wings negate the loss from the blade stall.
DeleteMine's flight science, but I'm a terrible student and our school doesn't have helos. My first guess without looking into it is that at a certain speed the wings provide enough lift that may maybe they can run the rotors slow enough or at a lower angle of attack to reduce the amount retreating blade stall. As to why we don't have it?- the design that preceded the Apache had big wings like that too and the chairforce threw a fit because it looked too much like an airplane. AH-56 it was.
DeleteSikorsky is working on bringing some of that technology back with the S-97 Raider which they are developing from their X2 demonstrator vehicle. I remember seeing a proposed Blackhawk-esque version using the same technology at a conference a good while back too.
ReplyDeletehttp://en.wikipedia.org/wiki/Sikorsky_S-97
See also: http://raider.sikorsky.com/
DeleteI would be interested in the weight of this compared to a regular Blackhawk.
ReplyDeletehttp://www.aviationweek.com/Article.aspx?id=/article-xml/awx_04_10_2013_p0-567246.xml
ReplyDeleteThere is also this from Boeing/Sikorsky
ReplyDeletehttp://en.wikipedia.org/wiki/Sikorsky_X2
Newer underestimate interest in buying new toys as opposed to reffiting ones they already have. More cushy jobs await in new ventures with huge contractors like LM and co.
ReplyDeleteThe wings do take over at higher speeds and the blades are turned to neutral lift to reduce drag. They also added two jet engines onto a Huey in the 60's as well. http://en.m.wikipedia.org/wiki/Bell_533
ReplyDeleteI belive the problemwith wings is that you get improved high speed performance at the expense of hover/NOE performance. Not only are the wings deadweight at hover and low speeds, they actually impede the rotor downwash, reducing the available lift.
ReplyDeleteYou see this, even without the ducted fan, with the Hind. It's surprisingly fast and agile at speed due to the wings but it's a dog in hover. It's notable that no one, not even the Russians, has repeated the Hind approach: even they either emphasized NOE (MI-28) or used co-ax rotors for speed (KA-52). The US made a similar choice in going from the AH-56 (emphasizing speed with wings) to the Apache (emphasizing NOE, no wings).
Sikorsky's ABC is an attempt to have their cake and eat it too: they avoid the high speed limitations of blade stall without the weight and lift obstruction of wings.
interesting that you talk about NOE and wings have nothing to do with each other. i know the army likes the hover behind a tree and pop up flight profile but the Marine aviators are on speed all the time, you don't find them in the hover long at all. same goes with apache drivers. they're zoomiing around like there is no tomorrow. additionally in the anti-air environment of tomorrow i don't think trees will be enough when operating near the front lines. they'll be facing guns and missiles so hovering is out...even if it is to lob a hellfire at an armored column.
Deleteif you're right then the Army needs to take a serious look at their doctrine when it comes to the use of helicopters. even transports don't stay in hover long these days.