Members Login
Post Info TOPIC: The LHX Program


Veteran Member - Level 2

Posts: 121
Date: Feb 3, 2012
RE: The LHX Program
Permalink  
 


Cool images, Hell(i)Master. I'd be interested in seeing the full-size originals of those!

I find it rather odd how some Russian magazines, websites, etc have some of the rarest and indeed most detailed images and info on the Comanche.

__________________

Flyboy's Site



Veteran Member - Level 1

Posts: 69
Date: Feb 4, 2012
Permalink  
 

Flyboy, I can send You higher resolution pictures, just tell how? Pity, that I can not post them in forum!

__________________


Veteran Member - Level 2

Posts: 121
Date: Feb 4, 2012
Permalink  
 

Hell(i)Master, check your messages here.

__________________

Flyboy's Site



Veteran Member - Level 2

Posts: 223
Date: Feb 4, 2012
Permalink  
 

I know a lot of these have already been posted, but I figured you guys might like some higher res images for the files.  Also, all were scanned from the collections of the USAAM.

   Ray

 

LHX0003.jpg

 

Question:  Do any of you consider the XV-15 part of the LJX program?  I ask because of this slide from the Museum:

LHX0009.jpg

 

More goodies:

LHX0004.jpg

 

LHX0005.jpg

 

LHX0006.jpg

 

LHX0007.jpg

 

LHX0011.jpg

 

LHX0012.jpg

 

LHX0013.jpg

 

LHX0014.jpg

LHX0015.jpg

 

LHX0016.jpg

 

LHX0018.jpg

 

LHX0019.jpg

 

LHX0020.jpg

 

LHX0021.jpg

 

Sikorsky%2520LHX.jpg

 

ringtail.jpg

 

 

 

 

 



-- Edited by rotorwash on Saturday 4th of February 2012 04:48:56 PM

__________________


Veteran Member - Level 2

Posts: 121
Date: Feb 4, 2012
Permalink  
 

Really nice pics, rotorwash. Man I love that retro '80s/'90s look to those artists' impressions. Much appreciated you keep uploading these. You're making my archive bigger, that's for sure!

__________________

Flyboy's Site



Senior Member - Level 1

Posts: 500
Date: Feb 6, 2012
Permalink  
 

rotorwash wrote:

https://lh4.googleusercontent.com/-U9oNYnp-nNc/Ty1cTua0T4I/AAAAAAAAIYY/56pRxLE6VH8/s800/LHX0013.jpg


 

Really great collection, Ray, but that's actually a Sikorsky X-Wing proposal.



-- Edited by Stingray on Monday 2nd of March 2015 10:08:49 AM

__________________
Alan Dallas


Veteran Member - Level 2

Posts: 223
Date: Feb 6, 2012
Permalink  
 

Gunship wrote:
rotorwash wrote:

[pic] Removed because text area is stretched too far. -Stingray


 

Really great collection, Ray, but that's actually a Sikorsky X-Wing proposal.


 I got that same comment over on ARC when I posted these long ago and forgot.  oh well, it's still a funky design.  Goods catch.

   Ray



__________________


Veteran Member - Level 3

Posts: 305
Date: Mar 1, 2012
Permalink  
 

rotorwash wrote:

 

https://lh3.googleusercontent.com/-8jdcwCNajh8/Ty1cbDBdP5I/AAAAAAAAIYo/R_x6JCs-E-U/s800/LHX0015.jpg

 


 

That's an X-Wing too.

But good stuff anyway!!!!!!! smile



-- Edited by Stingray on Monday 2nd of March 2015 10:08:21 AM

__________________

Vince Johnson - A merciless enemy but a powerful ally.

                           dragonfire1.gif

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Veteran Member - Level 2

Posts: 223
Date: Mar 1, 2012
Permalink  
 

 

That's an X-Wing too.

But good stuff anyway!!!!!!! smile


 

Well at least I know this isn't an X-wing.  LHX Superteam-McDonnell Douglas/Bell.  Top to bottom, AH-64 advanced ****pit evaluation helicopter, Bell 222 with 680 rotor system, OH-6 NOTAR.

  Ray


-- Edited by rotorwash on Sunday 4th of March 2012 07:12:43 PM



-- Edited by Stingray on Monday 2nd of March 2015 10:10:37 AM

Attachments
__________________


Administrator

Posts: 3381
Date: Mar 1, 2012
Permalink  
 

Now THAT is an awsome picture! I didn't know the OH-6 NOTAR or Bell 222 were used for the Superteam LHX studies!!!



__________________
Brony rotorhead
--------------------------
               ζ  
--------------------------


Veteran Member - Level 3

Posts: 305
Date: Mar 1, 2012
Permalink  
 

Cool!!!! Thanks for the pic! wink



__________________

Vince Johnson - A merciless enemy but a powerful ally.

                           dragonfire1.gif

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Global Moderator

Posts: 1328
Date: Apr 2, 2012
Permalink  
 

Bell tilt-rotor proposal



Attachments
__________________
Airwolf_logo.jpg


Administrator

Posts: 3381
Date: Jun 12, 2012
Permalink  
 

Pages from a 1983/84 Bell Helicopter Textron Reference Guide from Mark Nankivil, showing the Bell BAT tilt-rotor:

 

xBell%20Helicopter%20Textron%20LHX%20-%201.jpg       xBell%20Helicopter%20Textron%20LHX%20-%202.jpg


-- Edited by Stingray on Wednesday 22nd of May 2013 04:22:37 AM

Attachments
__________________
Brony rotorhead
--------------------------
               ζ  
--------------------------


Administrator

Posts: 3381
Date: Jun 13, 2012
Permalink  
 

More goodies from Mark...

Bell/McDonnell-Douglas LHX brochure:



Attachments
__________________
Brony rotorhead
--------------------------
               ζ  
--------------------------


Administrator

Posts: 3381
Date: Jun 13, 2012
Permalink  
 

Boeing/Sikorsky borochure:



Attachments
__________________
Brony rotorhead
--------------------------
               ζ  
--------------------------


Veteran Member - Level 2

Posts: 121
Date: Jun 16, 2012
Permalink  
 

Awesome pics, Stingray! More goodies for my own archive!

__________________

Flyboy's Site



New User

Posts: 4
Date: Apr 30, 2013
Permalink  
 

Greetings All.  First Post.

 

I would like to ask some general questions about the McDonnell/Superteam 'Shark' LHX concept.

 

1.  As cool as it looks, there is definitely a scifi theme here.

Everything from the bubble canopy which would have certainly impinged on the rotor disk if it opened upwards to the needless complexity of the curved wing leading edge and the lack of systems like the NVPS or (visible) landing gear?  Was there ever any actual prototype hardware or mockup built or drawings released?  Even just a definitive set of dimensions?  Or was the McDonnell/Bell concept in fact so secretive that, likely the 'ATF' which morphed into the F-22, there was never any real correlation between the concept art and the (unbuilt) real aircraft?

 

2.  I can find no definite shots of the landing gear or weapons bays.

This bothers me because I had always been told that the aircraft in fact -had- those large pectoral fins, errrr, 'wings' because they were designed to house weapons bays, keeping the fuselage structure clear and unholed.  But what little I am able to piece together from the concept art in fact suggests the exact opposite with clear evidence of tandem weapons bay doors on the fuselage centerline and what look to be large rectangular panel outlines on the wing underside which could be landing gear bay doors.  Because they are too short and broad to house FFAR pods or Hellfire.  This would make the wings large fuel tanks and carry through structure on which to mount the twin T800 engine pallet perhaps?

 

3.  Just how do you get into it?

Again, there are only vague hinge covers extending from the back of the canopy frame visible in the topdown view of the single seater concept art on this forum.  Which makes no sense because of the proximal rotor disk.  Do you honestly have to stop the rotors just to trade out aiircrews or talk to the plane captain?  I don't think so but there is absolutely zero evidence of longitudinal frames which would support a side hinged door that is typical of attack helicopters.  The Army typically likes to operate in all weathers which means such a means of ****pit access would leave more of the ****pit covered than the next best alternative: a rotating clamshell canopy such as those on the Rafale.

 

4.  There is mention of a 'tail thruster'.

On one of the few historical pages covering the McDonnell/Bell portion of the program.  Does this mean that the aircraft's NOTAR fan could be exhausted rewards in high speed flight, making it a VTDP hybrid like the Cheyenne?  The tail is actually rather blunt in shape, given that it

 

5.  Where did Tri.mil go?

There used to be a superb technical history webpage with all kinds of rare black and white photos and drawings of Vietnam era to present day rotary wing weapons systems and airframes.  I believe it was hosted out of Ft. Rucker.  I thought I might drop in there to see if they had anything on the targeting FLIR or chain gun for the LHX but Google cannot seem to discover where it went?

 

 

Sorry for all the questions but thanks for any help in advance.  Kurt



__________________


Global Moderator

Posts: 1328
Date: Apr 30, 2013
Permalink  
 

Hai there, welcome! :D

 

Kurt wrote:

1.  As cool as it looks, there is definitely a scifi theme here.

Everything from the bubble canopy which would have certainly impinged on the rotor disk if it opened upwards to the needless complexity of the curved wing leading edge and the lack of systems like the NVPS or (visible) landing gear?  Was there ever any actual prototype hardware or mockup built or drawings released?  Even just a definitive set of dimensions?  Or was the McDonnell/Bell concept in fact so secretive that, likely the 'ATF' which morphed into the F-22, there was never any real correlation between the concept art and the (unbuilt) real aircraft?


 Sci-fi is best fi. xD

Well if you want to attract the customer, it has to have some kind of appealing design aesthetic. Hence the awesome sci-fi-ish look. Even if the resulting machine would differ from the concepts, which everything eventually does so that it can meet the customer's requirements. I especially agree that the swept wings are a bit stylized over real world practical use. :P

The landing gear I've always assumed was retractable like in the Boeing-Sikorsky (First Team) proposal.

I don't think anything of the Superteam design ever got built aside from the modified evaluation aircraft used to test some of the proposed systems incorporated with it (AH-64 ACE, Bell 222, OH-6 NOTAR). Though there is a rumor that a prototype did in fact get built and test-flown, but I think this was confirmed a mix-up with one of the other test aircraft already mentioned.

Kurt wrote:

2.  I can find no definite shots of the landing gear or weapons bays.

This bothers me because I had always been told that the aircraft in fact -had- those large pectoral fins, errrr, 'wings' because they were designed to house weapons bays, keeping the fuselage structure clear and unholed.  But what little I am able to piece together from the concept art in fact suggests the exact opposite with clear evidence of tandem weapons bay doors on the fuselage centerline and what look to be large rectangular panel outlines on the wing underside which could be landing gear bay doors.  Because they are too short and broad to house FFAR pods or Hellfire.  This would make the wings large fuel tanks and carry through structure on which to mount the twin T800 engine pallet perhaps?


 One thing to consider is that the majority of these concepts are just artists' impressions, not guaranteed to be 100% technically correct to the official specifications. But I think I have a theory as to why they appear this way...

The idea of the wings are not too different from what we've seen on optional RAH-66 layouts, even if a bit more stylized. Internal weapon bays are present in the fuselage, while the wings can optionally carry additional weapons or auxilliary fuel tanks to give more flexibility to tactical demands. The mounts or pylons are lacking from what I can see in the pics, yeah... but this is the most likely reason (IMO) behind them. You could be right about the front landing gear being stored in them as well. Kind of like the AH-56, but actually in the wings themselves rather than the side fairings that the wings are mounted to.

 

Kurt wrote:

3.  Just how do you get into it?

Again, there are only vague hinge covers extending from the back of the canopy frame visible in the topdown view of the single seater concept art on this forum.  Which makes no sense because of the proximal rotor disk.  Do you honestly have to stop the rotors just to trade out aiircrews or talk to the plane captain?  I don't think so but there is absolutely zero evidence of longitudinal frames which would support a side hinged door that is typical of attack helicopters.  The Army typically likes to operate in all weathers which means such a means of ****pit access would leave more of the ****pit covered than the next best alternative: a rotating clamshell canopy such as those on the Rafale.


 Its that darned stylized aesthetic over practicality again. :P

No worries, the actual specifications would have undoubtedly keep this in mind should Superteam ever have built the beast. ;)

 

Kurt wrote:

4.  There is mention of a 'tail thruster'.

On one of the few historical pages covering the McDonnell/Bell portion of the program.  Does this mean that the aircraft's NOTAR fan could be exhausted rewards in high speed flight, making it a VTDP hybrid like the Cheyenne?  The tail is actually rather blunt in shape, given that it


 Good question! That would explain a lot actually... I had not actually considered that.

Also, did you have more to add to this question? You kind of ended abrubtly there. :P

 

Kurt wrote:

5.  Where did Tri.mil go?

There used to be a superb technical history webpage with all kinds of rare black and white photos and drawings of Vietnam era to present day rotary wing weapons systems and airframes.  I believe it was hosted out of Ft. Rucker.  I thought I might drop in there to see if they had anything on the targeting FLIR or chain gun for the LHX but Google cannot seem to discover where it went?


 I honestly have never heard of it, sorry. :/



-- Edited by Leela25 on Wednesday 1st of May 2013 04:19:52 AM

__________________
Airwolf_logo.jpg


Veteran Member - Level 3

Posts: 427
Date: Apr 30, 2013
Permalink  
 

Leela25 wrote:

Well if you want to attract the customer, it has to have some kind of appealing design aesthetic. Hence the awesome sci-fi-ish look.


 That's kind of true but at the same time contradictory to the whole competition. Let's not forget the designs that were scrapped due to not meeting the program requirements. Correct me if I'm wrong, but the customer here is in fact the military, who puts efficiency and practicality first rather than aesthetics.



__________________

We have here the latest in primitive technology.

Internet + Opinions = OMG we are SCREWED!



New User

Posts: 4
Date: May 1, 2013
Permalink  
 

Hi Leela,

Thanks for your response to my post.  Love your icon, is that the old Loral 'ATF' that decorated so many Aviation Weeks back in the day?

I agree that a weapon has to look beautiful to appeal to it's purchaser (Congress), regardless of how functionally efficient it is to it's program mangement agency as enduser (The DOD as Service Branches).  While the YF-22/YF-23 EMD downselect is probably not a good example (though the F-22A is far less ugly than the YF-22), the X-32/X-35 certainly are and it is my personal opinion that the cubist wonder known as the RAH-66 took the angled planes concept of first generation stealth to such extremes that cancellation followed as naturally as night upon the day.  Because that puppy was wrinkle-dog ugly and not in a cute way.

That said, if you look at some of the ca. 1991 posts on page 1 of this forum, the late Super Team design is almost a 100% reversal of it's 'original' form, with looks more akin to the Cobra than the blended shark shape of the concept art.  Things like the FLIR sensors moving from the front of the doghouse to the nose mark a radical (and unfortunate, IMO) change in tactical as much as engineering choices.  The weapons wing is now solidly geometric with angled leading edges and razor straight parallelogram geometries such that there is no longer -room- for there to be landing gear in them (Is it still a tail dragger like the UTIL was?  Or is it now a tricyle?).

Some parts of the upper forward fuselage are now heavily angled, drastically reducing the size of the canopy enclosure to the point where the crew head room is going to be tight.  Yet the lower fuselage where one would think most lowerhemisphere radar would impinge, is practically slab sided whereas the original artwork showed almost a circular constant taper.  The rear tail boom is flatly ugly being stepped down from the engine fairings like a Cobra to a faceted Stop Sign geometry which can't have been healthy for the size of the NOTAR fan.  Overall size and configuration of all design elements are so markedly different it is almost as if a major change in structural design lead to a different airframe as mission concept altogether (could this 'secret prototype' have effected this?  I admit I had not heard that rumor...).

What I meant to say about the tailboom of the concept art helo before I was so rudely interrupted by temporary senility was that it was needlessly blunt for a stealth enclosure but some of the artwork showed a _small_ opening that could be taken to be a hint at being an ejector nozzle.

Where's my proof?  Well, there's this to begin with-

>
Another important project undertaken by MDH was their research into the 'No-tail-Rotor' (NOTAR) concept. Replacing the tail-rotor by an internal tail fan with air circulation slots, a converted Army OH-6A helicopter was first flown on 17 December 1981. In 1985 a modified composite fan was fitted to an MD500E and flown in March 1986. The system used a variable-pitch fan forcing low pressure air into a hollow tailboom where the air is vented through slots along the right side of the boom and through a thruster at the end. There are many advantages in replacing the vulnerable tail rotor by an internal fan. In military terms helicopters are able to operate closer to objects without the fear of a tail-rotor strike and NOTAR helped to expand the helicopter's flight envelope increasing sidewards and rearwards flight speeds and yaw stability. It is also less susceptible to damage, with tests showing the system remaining effective after severe damage to the tail boom.
>

https://sites.google.com/site/stingrayslistofrotorcraft/bell--mcdonnell-douglas-lhx

And then there's the imagery-

http://www.aviastar.org/foto/mcdonnell_lhx_1.jpg
http://files.activeboard.com/958217?AWSAccessKeyId=1XXJBWHKN0QBQS6TGPG2&Expires=1368057600&
Signature=h7wg7Rk723ifhseU8ffcqxxCdmQ%3D



Which shows a design that has a rather suspicious (conformal is rarely the best way to get high massflow) NACA inlet on one side of the fuselage _ahead of_ of the main fuselage:tail boom attachment frame, indicating a desire to maximize fan size at the point where the fuselage is widest.  While both engines  exhaust through a single vent on the opposite side, also indicative of a rather demanding volume trade as signature concession as a T or Y shaped division of 'plumbing' inherent to intake trunking vs. exhaust hotpipe (or maybe a mixing plenum?) inside that again, quite splayed, hippish, point where the angular forward fuselage becomes the almost cylindrical aft fuselage.

Certaintly the pressure ratio of a 32-36" fan exhausting through an 6-8" nozzle would be significant in terms of thumb-over-waterhose propulsive force (probably enough to blow the tail off once you closed the NOTAR ejectors...) but again, if the bluff shape of the early tail cone is in fact an attempt to hide the obvious feature by simply not depicting the -size- of that fan plenum nozzle correctly, it could be that there was a 12-15" exit diameter nozzle there, possibly even a condi.  The fact that the concept art tail boom in fact has large, longitudinal, _external_, stiffeners on it tells me that it was indeed a pressure vessel of some kind.  Another signature sacrifice you would not nominally make on a 'stealth helicopter' unless the trade off you were getting was say a 200 knot topend.

Which is where 'scifi' starts to become engineering driven feature-realism.

Because if you think of the period 1983 understanding of stealth; outside specialist houses Northrop (Have Blue/Tacit Blue), Lockheed (Have Blue and the A-12/SR-71) and maybe Teledyne Ryan (various drones), there really wasn't much expertise in the U.S. aviation industry as a whole.

The conventional understanding promulgated at the time was that simple, bluff, shapes with low amounts of surface feature clutter and no sudden changes in contour (as corner relectors on **curved** stubwings...) was better for reducing radar return than angular shapes.

Of course this generalization is false.

We know now that while optical scattering rules in the fire control bands typical of mobile ADV and fighter radars (10GHz and up), Rayleigh/Mie resonant speculars still offer a base multiplier based on wave creep and resonant secondary harmonic frequency steps in the 90-100MHz step.  What this means is that a rounded object treats behaves like a total target dipole because there is no chine division which splits and isolates that impedance loaded energy variable, raising reflectance energy by some .26 times base cross section.  That's a one third gain in RCS folks.

http://www.radartutorial.eu/18.explanations/ex22.en.html

In fact it's worse than this because curved surfaces act like funhouse mirrors, distorting the returns band energy peak distirbution levels somewhat but also scattering it in all directions, generating potential for near-dirt multipathing that a target illuminator can see instead of tightening it into a neutrally oblique, deflection sectors which it cannot

The exception proving the rule is the B-2 bomber uses deep RAM/RAS and has constantly varying lines of curveature across an enormous 172ft wingspan which in fact attenuates and shifts the return in short frequency shifted segments rather than allowing large travelling waves to form.

At any rate, Sikorsky did their homework or got advantageously 'clued in' at some point (which is strange in and of itself, given the giant that MACDAC was and their period participation in the ATA-12 program...) and thus, when the early details of Gen-1 Stealth started to become available with the first distorted image of the F-117 in 1988-89 and the release of Ufimtsyev's model of facetting to break up total return area into microplanes that it's design was based upon, the First Team were able to rapidly adapt their extant airframe model (note the sponsons as volume savers)-

http://files.activeboard.com/958123?AWSAccessKeyId=1XXJBWHKN0QBQS6TGPG2&Expires=1368057600&
Signature=VW9Tbo9R1fKxHV9rFRYeBEg3wQM%3D


By splitting the fuselage in half and 'twisting' large features like the Fenestron housing 30` off alignment with the centerline, thus providing a clear upper/lower hemisphere chine line as delineation separator of the total fuselage return area when viewed from any vertical angle or aspect.

Which is where things begin to get tactical.

Because, if you've ever studied Joint Air Attack Team doctrine from the early 80s with the Sled and Skid (Cobra/Kiowa), you'll note that it's all about a low speed, very low altitude, attempt to work the terrain folds in places like the Fulda and Hopf Corridors where hills and forested treelines break up rolling farmland as the ideal of ambush force favored anti-armor terrain.

And so, rather than a 'Firebirds' type engagement model of swoops and zooms at guns and rocket range, attack aviation vs. armored mainforce is closer to an extended NOE hover taxi at walking speeds with some shots showing a guy literally hanging off the doorpost of the OH-58A/C rear cabin with a handheld laser ranger because we didn't have powered optics of even the AHIP-D to extend the acquisition range of our scout force.

Now imagine that kind of 2-feet-off-the-ground action in a 'fighter' helicopter that has to retract it's landing gear for both performance and RCS reasons and so has no jounce margin to as oleo travel to protect it from accidental CFIT.

You now have a major flight safety as much as tactical problem to engineer solutions for.

Enter the NOTAR with thruster.  One of the neat things about Cheyenne and hybrid helos (X-2) in general is their ability to make flat accelerations without cyclic pitching the airframe, something which both hotsides the entire upper fuselage decking, 'flashing' engine venting, doghouse, horizontal stabilizers and main rotor hub detail features to whatever radar cares to look.  And also teeter totter limits total acceleration vs. clutter masking to the angle which you can achieve without digging the nose or hover flaring the tail boom into the dirt.

This is why period scouting was slow, even on nominally agile (compared to the Sled and Indian) LOHs.

Of course, if you can use a diverter valve to send an increasing amount of air through an aft thruster, closing down the NOTAR as airspeed rapidly builds up enough for the very large, all moving rudder and stabilator to maintain directional control via aerodynamic forces, you don't have this problem because the airframe:earth longitudinal index stays flat.

But you still need to be able to rapidly reverse the process at high disk loading (as main rotor speed) without blooming up your altitude on all that stored potential lift energy.

Which is where the veritable barn door sized MLG covers on the underside of the wings, perfectly centered at the airframe CG and acting in cooperation with the all moving tail slab, can act as speed brakes in taking you from an effective 90-120 knot NOE sprint profile to something closer to down to zero airspeed in the airborne equivalent to infantry sprint-to-cover bounding movements.

Speed in the approach minimizes the time some TC on airwatch in a T-72 or Zip Gun can glance over at the flash of movement on the horizon and VISUALLY see you, 'creeping along' at 20-30 knots for extended periods between  terrain masks.

In time to lob an SA-14 or AT-11 airburst round at you from extended range.

Of course there are still issues...  Massive changes in airspeed close to the ground induce parallax blur while a lack of defined horizon line in varied terrain elevation model conditions means the pilot may not have an early enough cue to a sudden dip-then-rise in dirt height which his radar altimeter or digital TRN map shows as an averaged slope model but his nose will NOT real-world clear without scraping the gun off.

Yet there were systems, like the millimeter wave ROMEO radar and a couple of LiDARs whose program names I don't remember, that could detect this kind of change (as well as power lines and sundry other chopper killer obstacles) in a sufficiently timely manner to 'blip' the rotor disk in a single cyclic pulse to go up an over any random bumps and lumps.

Even as it primarily ensured safe rotor disk standoff from a sudden-decelerative rushed approach to treelines and structures used as direct optical masking.

Provision for this system would would explain why the nose of the McDonnell and indeed many of the other LHX concepts was period solid, often with a dielectric radome tip, rather than mounting the electrooptics as with the Cobra and Apache.

Just as a shorter sightline over the nose and a deeper windscreen were two of the reasons (along with greater agility and less mass inertia) for why the OH-58 was chosen as scout so too is it telling that the LHX also moved the pilot to the forward seat from a nominal balance sensing location closer to the rotor mast.  If you are using a NOTAR thruster and making flat approaches, you no longer need to worry so much about sensing airframe pitch angle relative to the rotormast teeter point (this is also one of the few good arguments for going to a single seat ****pit in the low altitude anti-armor mission btw...).

Signature wise, since the McDonnell/Bell LHX in it's forward fuselage is clearly more angled and actually fairly stealthy, even by modern standards, and doesn't adopt a tapered cylindrical scattering shape until aft of that major frame station point that is the midbody:tail boom break; it becomes possible that the Super Team simulator tactical modeling was all oriented around low RCS protection _solely as emitter viewed from the frontal aspect_.

Thus letting them make a deliberate performance trade (NOTAR plenum) vs. all-round RCS vulnerability on the assumed basis of being faster than the force you escort as having a significant tactical leverage (AH-64 = roughly 145 knots, AH-1F = roughly 125-130, depending on load and temp); LHX having originally been conceived against the Red Book performance estimates of the then unknown KA-50 as a 'fighter helicopter' (ABC presumptive performance in the 200 knot regime).

An aircav type screening at treetop height flying right over the rotor head of attack helicopters, compressed to the dirt in anti-armor ambush hides would have been disastrous as the lead sweep helicopters would call in fire from elevated trailing flight commanders in the typical threeship 'troika' formation.  The only force-exposure solution to which would have been rapid 'in and out' targeting of vehicles while keeping the Apache stoof off, lobbing AAWS-H Hellfire from 8-10km behind.

The Russians weren't dumb, they used helicopters in Regimental sized formations of 70+ aircraft for main defensive line assaults and would certainly have flown attack helos as security elements around any resultant breakout by OMG.  Just to contain the kind of Clancyesque ambushes by jeep or a helo mounted ATGW as continual threats to command tanks and mine flails.

An LHX which could match airspeed with high tech electrooptics for night work would still have the advantage here as a stealthy scout because front quarter LO lets it rise up into the radar line of sight while using standoff aided classification sensors to pick targets or face-shoot Hokums with MLMS/ATAS.

Sprint to cover employment of terrain masking then becomes predominant (to offset rear quarter RCS visibility vs. IP ambush set Air Defense Vehicles) only when operating in cross-FLOT modes to attrite 2nd echelon as followon exploitation forces and logistics columns.

Such effectively BAI being another mission set that a _high speed_ LHX would have been tasked to as part of Air Land Battle 21 deep battlefield doctrine.

So what changed all this?  Well, around time of PDRR program choice in 1990-91 we have Operation Flog The Iraqis, with the popularity of the F-117 and stealth in general now taken out of all proportionate applicability of it's NARROW tactical role.

Particularly for a helicopter operating in a principally visual threat distance arena this is ridiculous.

With final LH program downselect looming nigh, McDonnell 'hears' that Sikorsky has true radar LO nailed.

What are they to do to make themselves more competitive, what can they change?

http://files.activeboard.com/958174?AWSAccessKeyId=1XXJBWHKN0QBQS6TGPG2&Expires=1368057600&
Signature=FCoYKx3yu7X5A9lhjpWRgrPB4%2F4%3D


http://files.activeboard.com/958173?AWSAccessKeyId=1XXJBWHKN0QBQS6TGPG2&Expires=1368057600&
Signature=CwcoRazuQ2WZRvyUi9%2FcJDQEDs0%3D


First, they narrow the overal frontal crossection of the fuselage to a slab sided pug shape with the corner reflector of the swept-forward EO sensor housing moved from the simplified doghouse location to the nose.  Explicitly to add an angular planform shaping deflector that integrates with a now sloped upper fuselage shape.

Similarly, Super Team make the much reduced NOTAR tailboom angular at the base of a large, steeply inclined fairing that is the U-boat conning tower engine group.  The NOTAR ejector itself is much larger offseting an anorexically thinned empennage.  The fpward fuselage NACA inlet is gone, implying a VERY long takeoff shaft for a fan position set directly in front of a new inlet directly in front of the NOTAR vents.

Finally, the blunted tail cone is now comically dunce-cap conical and quite large because the tail boom reduction means the NOTAR fan isn't big enough to service a proper propulsor and 180-200 knot performance has sagged in preference for low-RCS as be-all/end-all principle design driver (If I'm right, the original thruster nozzle would show 'glint' from the it's edges in C-X band and unless there was a blocking device, it's also likely that spinning fan blade resonant scatter would be an issue, though again, only from directly behind.).

Too little, too late, the Super Team concept now looks like a cubist arthouse version of a Bell AH-1 Cobra wherein the slab-sided effect of most of the fuselage now serves as a billboard reflector rather than a circular scattering one while the total internal volume of the air vehicle has declined to the point where things like long persistence fuel, weapons and landing gear bays are all tightly competed (compared to a standard helo where they are external) in volumetric engineering trades.

And Boeing Sikorsky whose attempt was more studied and less desperately reactive, won anyway.

The sad part is that it was all a mistake, whatever was right or wrong about a NATO war configuration, the original McDonnell mixed performance design was better for the Post Cold war world where 200 knots on the clock and 500 feet of altitude make for a lot harder target for Rifle/RPG-7 as trashfire.  While, all things being equal (NVD on shoulderfire SAM), DIRCM + Kinematic obscurrent flares @ 1,500ft equate to a longer reaction time in which to influence SA-16/18 proportional smart homing than simple reliance on iffy reduced-not-low IR observables.

This in turn is why General Schoomaker, when he spoke of cancelling the LHX in 2004 after 20 years, 6.9 billion dollars and 12 major program restructurings, said 'it was the easiest decision of my life'.

Radar LO is _pointless_ when you throw away high end stealth technology every time some irate farmer with a bolt action Brno rifle or savvy threat commander with a layered ambush scheme blows up your super choppers, enmasse.  As happened in 2003 OIF to an entire attack aviation battalion of the 101st Airborne over Najaf in a desert/urban environment where there was no threat axis to orient on and no terrain mask to hide behind.

Further to this, the performance compromises inherent to the Low Observable structural optimization effects on drag and weight rendered the Comanche little better than the heavy-Hellfire Apache it was originally supposed to escort and perhaps replace as a 'cheaper' gunship.  Indeed, one of the insurmountabe barriers that the RAH-66 program ran up against was that the T800s had simply used up all their available power reserve as weight continued to rise in a preproduction platform that didn't even have most of it's MEP installed from Guns to Longbow to EOTAS.

All of which were just empty aerodynamic fairings on the PRDDs at that point.

So... here I am trying to model a masterpiece-

http://fc07.deviantart.net/fs70/f/2010/038/f/0/L_H_X__by_bagera3005.png

Of concept art and thinking to myself that what -is- visible can't all be based on imagination as showmanship because there is too much detail and it almost makes sense, at a fairly high technical level.

Now maybe I'm seeing justifications that aren't really there.  Maybe I'm not.  But a set of dimensioned 3-view drawings and detail images of things like the landing gear, ****pit and weapon bays from the earlier McDonnell LHX would still make building the replica a lot easier.

Which is why I am here, at the Mecca of all things Rotary Wing...


Kurt

 



__________________


New User

Posts: 4
Date: May 2, 2013
Permalink  
 

Well, Well, Well...

 

Early Period 1983 LHX ****pit Studies, SCAT-LTU-LOH in the Air Land Battle 2000 scenario and a decent cutaway of the Sikorsky ABC.

http://www.rucker.army.mil/avjournal/1980/1983/AVN_DIG_1983_01.pdf

 

KRASH absorption modeling of **Tricycle Gear** UTIL!

http://www.rucker.army.mil/avjournal/1980/1983/AVN_DIG_1983_01.pdf

Amazingly enough the general arrangement drawing is that of an A-109 with NOTAR.

 

This means an equally surprising yet aesthetically pleasing tricycle gear instead of the concept art tail dragger design.  Which matches some recent discoveries I have made of airframe panel lines in the Super Team SCAT fuselage sides as well as a reconsidered issue with the weapons bays on the fuselage needing to sit taller (to clear the loading of Hellfire onto rails without putting the crews on their knees) with less surrounding MLG obstruction than the mid-mounted wings could support without some -very- long struts.

 

Moving the MLG bays to the centerline narrows the stance a bit but also lowers the attachment point structural tube fittings further down the main fuselage frames without the complicating structural flex of the wings to fuselage joint.  It also allows for some fairly long struts using two axis extension (out and down) with diagonal rotation to provide best 'sprawl' of crocodile like stance at low sideload penalty.

 

Of course, assumptions of structural layout commonality between the Scout Attack and Utility variants brings it's own risks but I think the three views of the UTIL must be fairly accurate as they relate feature locations to structural load paths and airframe weight classes for specification of crashworthiness.

 

If the two types are generally similar (things like rotor mast pitch deviations and center of gravity static margins for things like the T800 engine mounts would have further locked in a basic configurational similarity as well as dimensions of fuselage length around 42ft/515 inches...), this brings problems of it's own in that I now have to find space for a nose gear that doesn't interfere with the cannon mount.

 

But it does make sense.  Because that long hollow fan plenum is not going to take a lot of compression stress without buckling at the top and shearing at the bottom and the taper effect of the boom provides some margin of flare without scraping the bumper on the ventral fin.  These are the two rough field characteristics (broken back and scraped tail in flare that leads to a nose smash) which traditionally make a taildragger essential in military helicopter design.

 

 

Kurt



__________________


Administrator

Posts: 3381
Date: May 9, 2013
Permalink  
 

WOW!!

First off, welcome to the forum, Kurt, I hope you enjoy it here.

Second, thanks so much for this brilliantly in-depth insight, questions, and feedback. This was all quite a read! I only wish I could answer it all, but unfortunately I'm still learning about this particular program as well.



__________________
Brony rotorhead
--------------------------
               ζ  
--------------------------


New User

Posts: 4
Date: May 11, 2013
Permalink  
 

Hi Stingray, 

Thanks for the reply, really nice play you've got here. 

There is a company out there by the name of Anigrand Models which does prototypes and one-offs for a lot of different eras and modes of airpower.  From WWII paper planes through the 1950s and onto the later Cold War. 

Some are even helicopters.  They have already done the AH-56 and S-67 for instance.

If I could get enough detail artwork of this aircraft on the ground as real working drawings I could maybe put together a prototype and get a McDonnell LHX cast by these folks in both a twin and single seat configuration.  The problem is that I am still short of images of exactly where all the bays and were.

If the wings are just giant fuel tanks and structural carry through to stiffen the fuselage over the weapons bay cutout on the centerline with perhaps mounting point shelf for the paired T800s ontop, that's one thing.  It would mean that-

 

1.  You have winglift to unload the rotor and increase RBS limiter speed.

2.  A work platform (albeit sloped) to access the engines.

3.  A means of masking the opening of the weapon bays from side view.

4.  A structural 'outrigger' means of keeping the aircraft upright in a CFIT with the landing gear retracted.

At the same time:

A.  You add a large addition to frontal area profile as RCS and wetted area as drag.

B.  You complicate facetting of the airframe into two separate vertical reflective hemispheres along a chine.

C.  You increase the rotor speed as disk loading by needing to compensate for blasting air down against the wings (this may in fact be why they are 'bent'...)

D.  You force the landing gear to extend beneath the plane of the tilted wing axis to provide it as well as the fuselage sufficient ground clearance.

 

It is the latter problem that presents me the most trouble because the one good view of the bottom of the fuselage I have indicates TWO weapons bays- 

http://img191.imageshack.us/img191/7973/xlhxmcdonnelldouglasbel.jpg 

Which, if sized to period Hellfire missiles with a 5" clearance on either end, means 138" or roughly 11.5ft of bay length.  Nearly the entire length of the wing.  This makes it almost impossible to locate the landing gear on the forward side of the station frame, ahead of where the NOTAR fan would be.  Landing gear bays that cross over this frame line force the fan to be smaller to pass air around their cutouts, lessening power to the NOTAR thruster and weakening the structural joint.  And the gear cannot fold forwards without hitting either the wingroots or the weapons bay door hingelines. 

The same picture which shows the large weapons bays also shows to large, flat, panels on the underside of the wing which -could- be MLG covers.  The problem then being that the MLG doors have to cycle (open and close) while the helicopter is still a significant (8-10ft) up in the air  and they further compress the wheel base between the NLG and MLG struts.  As stated earlier, they also have to be tall enough to keep the cannon fairing from scraping the dirt.

Particularly in the Single Seater version, wing mounted MLG as part of a tricycle gear arrangement instead tightens up the wheelbase to a nearly unmananageable degree, implying that the NLG retracts through the fairing behind the gun.

Speaking of the Single Pilot version- 

https://lh4.googleusercontent.com/-QBBAX1xdmwU/Ty1cUkwM5TI/AAAAAAAAIYg/
-KcGVKhO6Fg/s800/LHX0014.jpg

http://files.activeboard.com/958189?AWSAccessKeyId=1XXJBWHKN0QBQS6TGPG2&Expires=1369267200&
Signature=4y%2BtaxevxHtD9nIl8%2BSe1D%2FUrOQ%3D 

See that little door, just aft of the wing?  If that's where the MLG retracts into, it's got to either be an assymetrical arrangement that folds -crosswise- (one strut in front of the other) over the diameter of the fuselage.

Or it's got to be a strut-door which remains open after the main well door closes behind, on the sides of the tailboom (think AS-565 Panther).  Implying that there is a bigger door for the wheel, mounted aft.  Right in the flow line of the NOTAR fan.  Not a good idea.

 

Pictures as they say...



__________________


Administrator

Posts: 3381
Date: May 13, 2013
Permalink  
 

Kurt wrote:

Hi Stingray, 

Thanks for the reply, really nice play you've got here. 


 

Assuming you meant to say 'place', thanks! Happy you're pleased with it so far.

Just so you know, the links to the attachments are broken. Linking attachments in posts is not a great idea. Perhaps you can alternatively save, re-upload to your post, then insert them in the text where you want? (Let me know if you need help with this final step.) Just a suggestion for improvement on future message organization.



__________________
Brony rotorhead
--------------------------
               ζ  
--------------------------


Veteran Member - Level 2

Posts: 121
Date: Aug 5, 2013
Permalink  
 

Wow, seems I'm late to the party with these new updates. I haven't visited this forum in ages.

Kurt wrote:

5.  Where did Tri.mil go?

There used to be a superb technical history webpage with all kinds of rare black and white photos and drawings of Vietnam era to present day rotary wing weapons systems and airframes.  I believe it was hosted out of Ft. Rucker.  I thought I might drop in there to see if they had anything on the targeting FLIR or chain gun for the LHX but Google cannot seem to discover where it went?


 

I think you mean tri.army.mil?

You can find the site archived at the Internet Archive. Here are some links to get you started...

http://web.archive.org/web/20031223103214/http://tri.army.mil/lc/CS/csa/kptoc.htm
http://web.archive.org/web/20031226080904/http://tri.army.mil/lc/CS/csa/aaarmsys.htm
http://web.archive.org/web/20031226120223/http://tri.army.mil/LC/cs/csa/aaarmsy2.htm

As far as I can see, there's nothing on there about the LHX, only the Comanche.

More links from the Internet Archive can be found on the Links page of my Comanche website, under the 'Internet Archive' section...

http://digitality.comyr.com/Comanche/links.htm

 

Sorry I'm late, but hope this helps!

 



-- Edited by Flyboy on Monday 5th of August 2013 11:03:25 AM

__________________

Flyboy's Site



Administrator

Posts: 3381
Date: Dec 27, 2015
Permalink  
 

Early artist impressions of LHX-A type helicopters from AHS-Vertiflite No.3-4, 1980:



Attachments
__________________
Brony rotorhead
--------------------------
               ζ  
--------------------------


Administrator

Posts: 3381
Date: Jan 3, 2016
Permalink  
 

Did a major overhaul of this thread. Much more organized now.



__________________
Brony rotorhead
--------------------------
               ζ  
--------------------------


Veteran Member - Level 2

Posts: 219
Date: Jan 3, 2016
Permalink  
 

Some more BAT concepts, unknown sources.



Attachments
__________________


Global Moderator

Posts: 1328
Date: Jan 8, 2016
Permalink  
 

Good job on the organizing Sting. Retro, I dont think those are BAT concepts but let me do some research to find out for sure...



__________________
Airwolf_logo.jpg


Administrator

Posts: 3381
Date: Jan 9, 2016
Permalink  
 

Boeing/Sikorsky First Team concepts (SCAT and utility) from Aviation Week, January 19, 1987:



Attachments
__________________
Brony rotorhead
--------------------------
               ζ  
--------------------------
«First  <  1 2 3 4  >  Last»  | Page of 4  sorted by
 
Quick Reply

Please log in to post quick replies.

Post to Digg Post to Del.icio.us


Create your own FREE Forum
Report Abuse
Powered by ActiveBoard