200 KT Sea Hawk? Coming soon!

[HeyJoe]

The first flight of the fastest "Hawk" variant to date is fast approaching (no pun intended). NAVAIR began modifying a YSH-60F into a X-49 compound helo configuration in 2000 that will make it a world speed record contender and transferred the initiative to the Army in 2004.

 

[Scamahmrd]

Is this for real? How would you counteract the main rotor torque? Maybe the Vectored Thrust Ducted Propellor moves aft as airspeed increases. It's way beyond me, but sounds cool in theory anyway.

 

[bert]

Now if they could just deliver any of the current helos on contract on time...

 

[scoober78]

I put that right up there with this in terms of utility...

=

Neat though...

 

[TheBubba]

Wouldn't you have to worry about possible trans-sonic airflow over the forward moving blades of the main rotor? Or is 200 Kts slow enough to where it wouldn't be an issue?

 

[squorch2]

They slow the main rotor speed in order to reduce airspeeds over the blades as forward airspeed increases.

 

[MasterBates]

It's an issue with helos.. But if the rotors unloaded, it should be OK...

There is a balancing act with Nr... Spin it too fast, and you will have compressibility problems with the advancing blade... (and morestress from centrifigual force).

Spin too slow, and you have lower airspeed, lower lift, and a lower speed for onset of retreating blade stall.. Also, the blades use centrifugal force to provide them with "stiffness" to a point..

A compound helo, (this contraption) unloads the rotor in forward flight, so retreating blade stall is not an issue, and the compressibilty problem becomes more of a drag problem than anythign else.

 

[TheBubba]

I think I get it.

 

[Swanee]

How long until someone says, "Hey, how about putting a couple of hard points under the wings and let it carry more stuff" and it becomes the 200kt helo that tops out at 125kts?

 

[Gatordev]

Words

Besides the good description above by MB, here's some anecdotal evidence. I've been up to 180 in the -60B (downhill, of course). I'm sure bobby or the like can correct me, but I believe the Blackhawk can do 190+. So as long as it's not 400F degrees at 10,000 feet, 200 knots isn't out of the world for a regular helo.

I didn't realize they slowed the rotor down for this kind of contraption. That makes sense...well, conceptually. I wonder what widget actually makes it happen though...

 

[MasterBates]

I have heard of 60Bs going 205 indicated in a steep dive from altitude.. Due to some unfriendly electrons coming their way from an unfriendly place..

 

[bobbybrock]

Besides the good description above by MB, here's some anecdotal evidence. I've been up to 180 in the -60B (downhill, of course). I'm sure bobby or the like can correct me, but I believe the Blackhawk can do 190+. So as long as it's not 400F degrees at 10,000 feet, 200 knots isn't out of the world for a regular helo.

I didn't realize they slowed the rotor down for this kind of contraption. That makes sense...well, conceptually. I wonder what widget actually makes it happen though...

Are we talking VH our in a dive. I've been over two hundie in a dive. Level flight in a L I've been close to 170. The active duty bubbas are starting to field the Mike model with the 701 D with a wider cord line blade. I don't even think that model will have a top Vh of over 170.

 

[MasterBates]

Vh in the 60B was usually aroudn 140-150.. At normal FCF weights.. (no ordnance/search stores)

Anything more than that was in a dive.. I think I have seen 160 once for Vh, but that was a light block 0, that was noted for being a speedy bird.

 

[bobbybrock]

140 -150 is pretty typical in an A model 60. A little better in a L model. Of course the configuration plays a huge part. The HH's I fly for the guard are pretty heavy and they VH in the 145-150 range.

 

[MasterBates]

Do the 60A's have the same motors as the 60B? (GE T700-401C)

I'd have thought all things being equal, they would be faster, since they are lighter, and dont have the drag from the RADOME, ESM blisters, MAD Pylon/Bird, etc..