stealth chinooks? your thoughts

[slatts 1978]

last night, with nothing else being on the box, myself and the brother watch a documentary about the US mission to kill OBL. (channel 4's shoot to kill)

we all know about the stealth blackhawk, to reduce noise and to bypass the radar network. buuut they added a few chinooks flew in too as back ups. heres a jist of the replies and points :p

"wouldnt they be stealth too?"

"they flew below radar"

"yea but so did the blackhawks..why go to that effort if half your force is stealth..and those that aren't are flying trucks to a radar"

"yea but they were in the mountains and couldnt be picked up till they were in the town"

"still...why risk that?

of course there are others who thought the same months back, even someone came up with a design http://cencio4.files.wordpress.com/2011/05/mh-47x3.jpg

so, what do you think? my view is there was one

[maturin 12]

The chinooks weren't supposed to go at all, right? They were there in case something went wrong. Alternately, the anti-radar capability was only needed near the Abottabad military installations, or it was just used to get a head start on the operation.

[slatts 1978]

The chinooks weren't supposed to go at all, right? They were there in case something went wrong. Alternately, the anti-radar capability was only needed near the Abottabad military installations, or it was just used to get a head start on the operation.

yup

my view is that if you're gonna do such a risky as that whole op. why go to the bother of making stealth BH and have the chinooks risk giving the mission away?

EDIT: even if they were in the mountains, listening to even obama himself going on about how secret the whole thing was, i would say that they didnt let the chinooks go unmodified

[Maio 293]

How would you make a CH stealthy. Add a couple of angled panels to it;s exterior and coat it with radar absorbing paint? I can see this working with the UH it's smaller and sleeker , but the CH is big.

[max power 21]

The B2 is also very big.

I suppose anything is possible, but I wouldn't necessarily believe that the way it went in the documentary is exactly how it went down.

[slatts 1978]

How would you make a CH stealthy. Add a couple of angled panels to it;s exterior and coat it with radar absorbing paint? I can see this working with the UH it's smaller and sleeker , but the CH is big.

reduce its RCS and acoustics would be one thing. you certainly wouldnt make one disappear

[rksl-rock 1301]

I've only spent 10 mins thinking about this but as a first pass I don't think its really practical. You'd end up with almost a new airframe. :)

1. - Fully non-metallic composite blades. Either shorter chord length BERP or Blue Edge
   #2 like config. Something to reduce the noise signature. But this would also reduce the max payload and speed. If you've ever been near a Wokka when it flys by you will know what i mean when I say you feel them as much as hear them. This characteristic 'thudding' is caused by the huge surface area of the blades slapping the air. It would be very hard to mask. But it is these huge blades that allow it to lift so much.
   
2. - RAM Rotor hub covers - cover all the articulation kit, joints, hinges and linkages like the RAH-66 was intended to have. The rotor hubs make very good radar reflectors, they are huge lumps of forged steel or titanium after all.
   
3. - Replace the metal skin panels with pre-stressed composite panels as well as reduce the number of panels. Using pre-stressed panels will reduce the sagging and flex between ribs and remove the need for as many stringers. Reducing the number of panels reduces the number of seems and rivets that need masking.
   
4. - Cover all rivets and seams with durable RAM tape.
   
5. - Re-design Engine pods for lower IR signature. Alot of heat is radiated out of the engine and dispersed via the main rotor. Which makes the Chinook and easy target for IR missiles.
   
6. - Re-design Intakes for noise cancelling (The current ones apparently whistle at the right speeds) and full masking of the turbines and drive shafts.
   
7. - Re-design the exhausts. Something similar to the Apache's "Black hole" or Lynx's AH7 "Haybox" systems.
   
8. - Smoother all around surface. Blend the sponson tanks into the fuselage with no angle smaller than 50-60 degrees.
   
9. - Coat all windows with RAM clearcote
   
10. - Reduce the number of openings in the fuselage. Less edges etc
    
11. - Retractable gear with covering doors.
    
12. - Remove lifting hooks and all tie down loops.
    
13. - Remove all external antennas and replace with flush ones since the skin is no longer metallic.
    
14. - Retract the gun mounts and "brass" tubes while in transit. Its not easy to do with the current mounts even on the new 47F with the Crew master seats.
    
15. - Remove the Radar altimeter and the weather radar emitters. You could replace the altimeter with LIDAR (Laser equiv of RADAR). A lot of radar altimeters, if low enough, will illuminate the bottom of the aircraft at low level increasing your signature. I suppose you could use it for Terrain Following too. I'm not sure about weather radar though.
    

Edited May 4, 2012 by RKSL-Rock

[slatts 1978]

was waiting for you to say something lol

about the lifting cap. all i could gather from reports is that it was only troops inside, so nothing too heavy.

the whole new airframe, i would say the stealth BH would be a new-ish design too..same thing with retractable gear and guns. as for noise, they only needed to be in areas where they were heard in an emergency (pick up the seals from the downed helo) , and then go home so being heard might not have been as big a worry...and yes..i have been in a house while 4 flew over waiting to land a dublin airport(ty Mr. Obama :p ) so i know how loud they are :D

though like you i too spend about 10 mins thinking about it :p i just wanted a few opinions on it :D

P.S. nice jag in your sig ;)

[Hillsbills 1]

Well if the BH's went early at least they'd have a stealthy head start. They could already be on the target when the 47's showed on radar.

[PELHAM 10]

Anything is possible, they seemed to do most of Rocks list to the UH-60 - the tail rotor hub had a cover on it and just look at all of the other modifications including canted tail surfaces and different blades:

The chinooks would not need to be stealthy as the US could effectively use electronic measures to disable radar for the exfil. They needed surprise for the actual building raid but once that was over there is no need for stealth and surprise. Jam the radars and leave.

Edited May 5, 2012 by PELHAM

[Ghost22 1]

I cant imagine how Chinook can be stealthy. That thing is huge and loud.

[slatts 1978]

I cant imagine how Chinook can be stealthy. That thing is huge and loud.

so is a B2 and jet engines ;)

[rksl-rock 1301]

so is a B2 and jet engines ;)

Yeah but the B-2 flies at ~40,000ft. Not quite the same as a Chinook is it :P

[slatts 1978]

yea i speak before i think lol

[spooky lynx 73]

To make Chinook stealthy will be 10 times expensive than to fill it with newest ECM stuff that will jam all radars and radios 100 km around. It will be the same as Tu-22 and Tu-22M: formally two versions of one plane, in fact - two different planes having only the same nose gear.

[jagheterjan 10]

Jamming everything is - apart from being next to impossible when stuff needs to fit into a helicopter - the exact opposite of what stealth technology wants to achive. When you don't want anyone know you're coming, why broadcast it on ALL THE CHANNELS before you are even near?

[rye1 21]

How to make a Chinook stealthy: Take away its engines.

[dekster 1]

If you need something large, suited for low flight with a high payload and stealthy: why not use an airship?

[rksl-rock 1301]

If you need something large, suited for low flight with a high payload and stealthy: why not use an airship?

Because they are typically slow vulnerable to enemy fire. And for a "chinook size" carrying capacity the envelope (gas bag) has to be huge.

[DetCord 96]

Ugghh... supposed experts and armchair generals.

Guess what? It is not the engines that are audible. It's physics, that loud whomp whomp you hear when a helo is near, that is the tips of the rotor-blades breaking the sound barrier as they spin through the air. The only way to avoid that is to slow the turbine rotation down, and thus to an extent, making the aircraft more vulnerable to SAF in its various forms and spotting by enemy combatants.

[max power 21]

that loud whomp whomp you hear when a helo is near, that is the tips of the rotor-blades breaking the sound barrier as they spin through the air.

Nope.

The only way to avoid that is to slow the turbine rotation down, and thus to an extent, making the aircraft more vulnerable to SAF in its various forms and spotting by enemy combatants.

Nope.

Ugghh... supposed experts and armchair generals.

Indeed.

[roberthammer 582]

Stealth Chinook ? - i don't think so , it would be alot work to make it "stealth"

More reasonable option should be Osprey , because it can carry heavy stuff and also it is more faster than normal helicopter

[max power 21]

I wanted to quantify my answer so I calculated the tip speed of a hovering huey helicopter, which are arguably quite loud.

At a rotor diameter of 12.14m, and a rotor speed of 5.4 revolutions per second, we get a rotor tip speed of 206 m/s. The speed of sound at stp is 340 m/s.

The top speed of a huey is 61 m/s. 206 m/s + 61 m/s = 267 m/s.

As we can see, the tips of the rotors never get close to breaking the speed of sound. In fact, it stops 70 m/s (higher than the top speed of the huey itself!) short of it at its top speed in level flight- and I have heard these things passing over in level flight... you can feel it in your chest!

Feel free to check my answer. I may have had a beer or two before these calculations.

Edited May 31, 2012 by Max Power

[DetCord 96]

Nope.

Nope.

Indeed.

You're absolutely, 110% wrong. That said, so am I.... to an extent.

Because the blade is rotating, and not flying straight into the air, then the outer tip will be moving through the air faster than the base. In fact, the airspeed of the blade will increase as you move out. So what will happen is that the tips of the blades will be the first to reach mach 1. A shock wave will form at the tip of the blade. As the blade increases rotational speed, the shockwave will move along the blade as more of the blade goes supersonic. Perhaps tran-sonic to ultra-sonic was a more correct term.

This can be cut down significantly if the tail-boom assembly is a rotor-less, push pull fan.

Edited May 31, 2012 by DetCord

[max power 21]

Prove it ;)