CH-47 Chinook

[PR19_Kit]

...... operate 4 ASW Chinooks (which for a time were favoured instead of the Seakings at that time - Twin rotors were thought to provide a more stable dipping sonar platform and of course it had the capacity for plenty of sensors, weapons and fuel for endurance).

Now THERE'S an idea!  

Has anyone here had a go at that before?

[Thorvic]

...... operate 4 ASW Chinooks (which for a time were favoured instead of the Seakings at that time - Twin rotors were thought to provide a more stable dipping sonar platform and of course it had the capacity for plenty of sensors, weapons and fuel for endurance).

Now THERE'S an idea! 

Has anyone here had a go at that before?

As in building the ASW Helicopter in an aircraft scale ?, i dont think so although Martin may recall one before is joined the SIG.

G

[PR19_Kit]

I meant building a Chinook as an FAA ASW aircraft?

I'm imagining it in RN Dark Blue with big white nos. on the sides, with two sets of Mk 46s down each side of the sponson. The dipping sonar could be deployed over the open ramp perhaps? It might need a bigger side door, maybe with one sponson cut doo in length a tad too.......

I'll have the thing virtually built at this rate...... 

[GTX]

I meant building a Chinook as an FAA ASW aircraft?

I'm imagining it in RN Dark Blue with big white nos. on the sides, with two sets of Mk 46s down each side of the sponson. The dipping sonar could be deployed over the open ramp perhaps? It might need a bigger side door, maybe with one sponson cut doo in length a tad too.......

I'll have the thing virtually built at this rate...... 

Well, hurry up with the pics then!

Regards,

Greg

[Weaver]

I meant building a Chinook as an FAA ASW aircraft?

I'm imagining it in RN Dark Blue with big white nos. on the sides, with two sets of Mk 46s down each side of the sponson. The dipping sonar could be deployed over the open ramp perhaps? It might need a bigger side door, maybe with one sponson cut doo in length a tad too.......

I'll have the thing virtually built at this rate...... 

Deploying the dipping sonar from the tail would result in it being hoiked up and down with pitch-attitude changes as the Chook moved. I think it would be better to deploy it from a hatch in the middle of the belly: it's not like there isn't room...

The logical place for a surface search radar would be in a flat radome under the nose, in the manner of a Seahawk or Merlin, however that would compromise the Chook's amphibious capability, so if you wanted to make it "perversely British" you could give it the Sea King's radar "camel hump" on the spine in between the rotor pylons...   Perhaps a more practical idea would be to go for the two-aerial solution seen on the Super-Frelon, but put them on the sides of the forward rotor pylon, or lower a "flying saucer" radome out of the tail ramp.

[PR19_Kit]

Deploying the dipping sonar from the tail would result in it being hoiked up and down with pitch-attitude changes as the Chook moved. I think it would be better to deploy it from a hatch in the middle of the belly: it's not like there isn't room...

The logical place for a surface search radar would be in a flat radome under the nose, in the manner of a Seahawk or Merlin, however that would compromise the Chook's amphibious capability, so if you wanted to make it "perversely British" you could give it the Sea King's radar "camel hump" on the spine in between the rotor pylons...   Perhaps a more practical idea would be to go for the two-aerial solution seen on the Super-Frelon, but put them on the sides of the forward rotor pylon, or lower a "flying saucer" radome out of the tail ramp.

Hmm, I'd have thought that with current control systems a feedback signal from the pitch channel could be fed to the sonar winch to counteract the pitch issues.  But as the Chinook already has a belly hatch anyway, for the central cargo hook, putting the sonar there might work better.

The 'camel hump' radar would be at great risk of being thumped by either of the rotors in various flight and non-flight modes I reckon, but I take the point about having it on the bottom of the fuselage. In passing, it looks like the Navy have foregone their amphibious helicopter capability with the Merlin, as that's exactly where the Merlin's radar is fitted.

How about mounting the radar actually ON the floor of the ramp, and just lower it to the deployed position? Then if a water landing was need you could lift it back up again.

[NARSES2]

If I may be naive ? Why do you need to land on water other then in an emergency ? You can pick survivors up with a winchman ?

[Weaver]

Deploying the dipping sonar from the tail would result in it being hoiked up and down with pitch-attitude changes as the Chook moved. I think it would be better to deploy it from a hatch in the middle of the belly: it's not like there isn't room...

The logical place for a surface search radar would be in a flat radome under the nose, in the manner of a Seahawk or Merlin, however that would compromise the Chook's amphibious capability, so if you wanted to make it "perversely British" you could give it the Sea King's radar "camel hump" on the spine in between the rotor pylons...   Perhaps a more practical idea would be to go for the two-aerial solution seen on the Super-Frelon, but put them on the sides of the forward rotor pylon, or lower a "flying saucer" radome out of the tail ramp.

Hmm, I'd have thought that with current control systems a feedback signal from the pitch channel could be fed to the sonar winch to counteract the pitch issues.  But as the Chinook already has a belly hatch anyway, for the central cargo hook, putting the sonar there might work better.

With current systems yes, but I thought we were doing this in the 1960s for the Escort Cruiser?

The belly hatch is the way the Swedes do it with their 107s, and AFAIK they're the only outfit in the world to use a tandem rotor machine for ASW.

The 'camel hump' radar would be at great risk of being thumped by either of the rotors in various flight and non-flight modes I reckon,

Fair point: I wasn't being entirely serious anyway....

but I take the point about having it on the bottom of the fuselage. In passing, it looks like the Navy have foregone their amphibious helicopter capability with the Merlin, as that's exactly where the Merlin's radar is fitted.

How about mounting the radar actually ON the floor of the ramp, and just lower it to the deployed position? Then if a water landing was need you could lift it back up again.

Depends on what sort of water landing you envisage: the Chook can actually open it's tail ramp on the water with a special dam fitted to stop the cabin flooding, but that would still dunk a ramp-mounted aerial. On the whole, I think that either a retractable aerial or twin side-mounted ones is the way to go. You can put it on (rather than under) the nose of course, but then that makes an already long aircraft even longer.

Speaking of the ramp, an ASW Chook with the same sensors as a Sea King would have an awful lot of space to spare, so why not stow torpedoes and depth charges internally and simply roll them out of the back? That would give you enormous flexibility in weapon choice, not least when it came to tac nukes.

[Weaver]

If I may be naive ? Why do you need to land on water other then in an emergency ? You can pick survivors up with a winchman ?

You probably don't but it's the stated reason for the Sea King's radar not being under the belly, so presumably the same reasoning would apply to the Chinook.

[PR19_Kit]

Perhaps because that's the way the aircraft came from Sikorsky in the first place? 

In reality I don't think they do use the capability as a regular operational capability, but it might come in handy sometimes.

[NARSES2]

Thanks Weaver and Kit - glad I wasn't missing anything obvious 

[rickshaw]

If I may be naive ? Why do you need to land on water other then in an emergency ? You can pick survivors up with a winchman ?

You probably don't but it's the stated reason for the Sea King's radar not being under the belly, so presumably the same reasoning would apply to the Chinook.

I seem to remember there is a radar aerial on the Seaking "under the water" when it lands on water - its in the nose, below the cockpit.  So it is possible.  I think a much worse problem would be the clearance under the fuselage when landing for the Chinook.  There isn't that much room under there.   I think having twin antenna, one each side and a bow one would be sufficient and more useful.

[Weaver]

This is the sort of thing you can do with a Chinook on water:

http://www.youtube.com/watch?v=Wsq8ol9XJPY

http://www.youtube.com/watch?v=f7rqcKFcaBI&feature=related

[rickshaw]

This is the sort of thing you can do with a Chinook on water:

http://www.youtube.com/watch?v=Wsq8ol9XJPY

http://www.youtube.com/watch?v=f7rqcKFcaBI&feature=related

Second link shows just how "leaky" the hull of the Chinook is.  Check out where all the water comes out of when they lift off.  Now, is it SEALs as claiming in one or SBS as claimed in the other?

[Weaver]

I think that's mostly coming from the undercarriage sections of the sponsons and the winch hatch by the look of it, and don't forget, you wouldn't routinely open the tail ramp all the way on the water without the dam in place. There are loads of still photos of them landing on water and according to Boeing's website a) they're often pre-delivery tested in the river next to the factory and b) you can land on water and shut the engines down, so it's a proper landing, not just "hovering below sea level".

I think they're two different events rather than different videos of the same event. One claims to be a practice run and the other is supposed to be in Afghanistan, but how true that is? ......