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Author Topic: Northrop/McDonnell Douglas YF-23 and EMD F-23  (Read 496696 times)

Offline elmayerle

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #45 on: March 26, 2007, 09:46:29 pm »
The F-35 was lengthened before and after the cockpit for a simple reason, they/we needed the volume to install all the systems a fully combat-capable derivative of the X-35 would need (and it's still a tight fit to get everything in - think of putting on a pair of pants that -just- still fits).  To the best of my knowledge, the inlets of the F-35 are fairly similiar, if not indentical, to those of the X-35.

Oh, and as to dorsal inlets, they can be made to work at  high-AOA, but it takes some very careful tailoring of the forebody and LERX to set up the proper conditions.  Northrop demonstrated this in testing back in the late 1970s that was written up in the AIAA Journal of Aircraft.  Interestingly enough, after a few of these papers had appeared, none further did; this was at the time when Low Observables was becoming recognized as an area of design criteria in its own right.  I rather imagine that the implications of this technique sank in and further testing was classified.  I do know that one of Northrop's proposed YF-23 configurations took advantage of this to mount dorsal inlets over a double-delta wing.
« Last Edit: March 26, 2007, 09:54:24 pm by elmayerle »

Offline Sundog

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #46 on: March 26, 2007, 10:06:06 pm »
I would love to see that submission, with the dorsal inlets. Although it makes sense that Northrop has alot of  experience with them, just look at all of the early ATF northrop concepts when it was still just a strike fighter with the dorsal inlets and their VATOL design with dorsal inlets.

Offline elmayerle

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #47 on: March 26, 2007, 10:12:37 pm »
I don't have a copy of it and I seriously doubt there's one floating around as only the few folk who worked on that concept kept the illustrations; I just happened to work with two of them on another classified program.

Offline Ogami musashi

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #48 on: March 28, 2007, 01:24:36 am »

Quote
One of the reasons US don't like canards besides stealth are:
1. Very high trim drag. In supersonic flight the CG moves forward plasing more weight on the canards. They have less surface and to generate the nessesary lift have to turn at an grater angle. This creates more trim drag

2.Canards Stall before the wing, hence if your wing stalls you have no canards to help you out. I donít think we will ever see the Euro canards performing cobras without Trust vector control for this exact same reason.



The CG moves forward???????

the Canards stall before the wing?????

Any sources please.

Offline Woody

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #49 on: March 28, 2007, 02:33:48 am »
Overscan, please transfer this to the 'Scale Modelling, Fan Art & Profiles' area or 'The Bar' or otherwise do with it as you see fit.

So in short: IMHO you have created an aircraft with a very limited maneuvering flight envelope

Thanks Lantinian for the pointers, and mean that. I won't go on too much about my fantasy plane here as it detracts from the serious (if paradoxical) discussion of the real fictional plane, but, from my limited knowledge, I'll try and explain my reasoning:-

1. It was a quick drawing only as an exercise in illustration style and entertainment, as neither F-22 or YF-23 are not my favourite planes (first excuse).
2. The weapons bay is supposed to be wide and flat (its a fair comment) like the F-22s but bigger, and I probably would have moved further back to the C of G if I'd spent more time, but its still further back than on the real YF-23.
3. Like-wise I would have made the expansion of area under the intakes more gradual in depth to help area rule (see my previous retraction Reply #22) and as the intakes are hollow they wouldn't contribute so much and need not be too heavy.
4. Saying canards cause turbulence or reduce control can be applied to any canard plane (MIG 1.44?).
5. As for control power distance from the C of G: (see answer #2 and) remember I added heavy thrust vectoring nozzles at the back. And the moving canards are pushed along in front of the centre of rotation (which is probably a lot further back than you think) so probably still have (and for many other reasons) more power that equivalent trailing tail surfaces.
6. The intakes are on the top side as a bit of a laugh at the expense of some of the entries in the 'Re: Northrop pre-ATF and ATF studies" thread (Sorry guys), which as I already said (see my previous retraction Reply #22) I think is a bad idea.
7. Your reasons why canards are no good: trim drag is down to C of G verses C of lift (isn't it C of lift that moves backwards not C of G that moves forward ;D) and can be altered by weight distribution at the point of design. And cobra's are for airshows. All of which is addressed in the 'Cunards' thread.
8. Your friend's design is quite reasonable but is really not much of a change, as the wing position, tail and volume are unaltered. I do worry that the canards would impede the pilots view and perhaps fowl the air intakes. They are too far inboard to serve as close coupled slats for the wing though they might act as LEXs. They would however add weight and not add as much lift as my canard/widened body combination (IMHO).
Thanks again Lantinian; this is the sort of discussion I love and I look forward to your reply.

Cheers as ever, Woody

Offline flateric

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #50 on: March 28, 2007, 03:46:22 am »
Unconfirmed rumour I've heard that while Northrop didn't dig too hard into NATF-23 proposal, one of the carrier desk -23 variant was a canard ...with just 15% commonality with AF version.
"There are many disbelievers in
stealth, more than a few of them truly technically ignorant and proud of it." Sherm Mullin, Skunk Works

Offline elmayerle

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #51 on: March 28, 2007, 04:09:31 pm »
Unconfirmed rumour I've heard that while Northrop didn't dig too hard into NATF-23 proposal, one of the carrier desk -23 variant was a canard ...with just 15% commonality with AF version.

Going by the one model I saw, that's a fairly accurate rumor.  IMHO, the carrier version definitely was lacking in aesthetic appeal.

Offline flateric

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #52 on: March 28, 2007, 04:31:50 pm »
Needless to be an Einstein to make an parallel with later MDD-BAe ASTOVL/JAST GCLF concept to imagine overall shape of NATF-23.
While being known -23 nut, I can hardly, hardly, hardly imagine this sleak low sitter making 5G controlled high alpha crash with a hook extended on a carrier desk.

I wonder ..how much will we wait to see Northrop's ATF history in details... ca. 2015? I know that after Boeing-McDonnell 'merge' Northrop, many court actions were made to prevent leaks of information MDC got during teamwork on -23. Not the last point was technical documentation of the project. And in this case FOIA requests will do nothing to closely held while being dusty commercial secrets.
« Last Edit: March 28, 2007, 04:39:43 pm by flateric »
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stealth, more than a few of them truly technically ignorant and proud of it." Sherm Mullin, Skunk Works

Offline Sundog

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #53 on: March 29, 2007, 10:50:37 am »
Quote
Going by the one model I saw, that's a fairly accurate rumor.  IMHO, the carrier version definitely was lacking in aesthetic appeal.

That's the first I've heard of this, but this makes sense of what one of my friends said to me. AFter we graduated he went to work at Navair on the NATF and he talked about how "ugly" the NETF from Northrop was. When the ATF prototypes rolled out, I thought he must be high, because the YF-23 was so much better looking than the YF-22.

Now, upon hearing this, I realize he may not have been high.  ;D

Offline elmayerle

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #54 on: March 29, 2007, 02:21:44 pm »
Quote
Going by the one model I saw, that's a fairly accurate rumor.  IMHO, the carrier version definitely was lacking in aesthetic appeal.

That's the first I've heard of this, but this makes sense of what one of my friends said to me. AFter we graduated he went to work at Navair on the NATF and he talked about how "ugly" the NETF from Northrop was. When the ATF prototypes rolled out, I thought he must be high, because the YF-23 was so much better looking than the YF-22.

Now, upon hearing this, I realize he may not have been high. 

Trust me, he wasn't consuming psycho-active substances; the NATF-23 design I saw was nowhere near as attractive as the YF-23.  If memory serves me correctly, the main commonality between the two was in systems and equipment fit and the forward fuselage.

Offline lantinian

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #55 on: March 30, 2007, 04:33:54 pm »
Just to wrap up some thing up nefore internet service provider crashes again :D. Sorry guys if some of this posts stays of the topic.

Quote
the Canards stall before the wing?
http://en.wikipedia.org/wiki/Stall_(flight)Check at the end just before Spoilers. My reasoning is that because canard stal before the wing you never want your wing to stall unless you have a tail control as well. Hence the SU-47 design with canards and tails. ::)

Quote
The CG moves forward?
My Mistake :-[. Its the Center of Lift that moves forward in supersonic flight. Basically the CG and the CL for a canard design should be swapped. My CG estimation was based on the main landing wheel position and book says CL it approximately 1/3 down the wing chord.

However if we do indeed decide on the CG based on the top view, Woody would be right: the CG will be farther back, behind the wheel and the aircraft will fell on its tail! :o

If we correct the wheel position we still have the CL in front of the CG. In supersonic flight the canards will need to generate negative lift to keep the nose down. You have loss of lift in cruise flight and bonus lift in maneuvering. Unstable canards designs are not a good choice for long range fighters IMHO as a result of that.

Something else for Woody.
http://www.desktopaero.com/appliedaero/configuration/canardprocon.html
If you note on of the disadvantages of canards is that the center of grafity of the fuel end up behind the  CG of the Aircraft. Your design does not seam to do so :-\. I am still thinking on the implications of that ???

Quote
I would have made the expansion of area under the intakes more gradual in depth to help area rule
I still think having side by site weapons bays in the same line as the canards is a too big and increase in area ;). I would stick with the tandem weapons bay arrangement if I was you ;). its more aerodynamic.
Second, in the middle of the weapons bay you have a drop in the area  :( as the canards are gone and the forward fuselage starts to blend with the wing.

Quote
Saying canards cause turbulence or reduce control can be applied to any canard plane (MIG 1.44?)
Its the way you do it that doesn't feel right. All other canards planes have the canards set higher that the wing. IMHO to promote vortices on top of the wing. The MiG 1.44 has 2 vertical tails and has dogtooth edge on the canards to direct the vortex inward of the tails. Your canard design, IMHO will disrupt the wing lift and the vertical tails. >:(

If I would want to improve on the F-23 design I would not stray away from the concept (Northrop Formula) but rather go deeper into it: Example: Pelican tail, Aeroplastic wing, FB-23 type of exhausts (like the first post by Matej) with possibility of TVC sideways and up only. e.t.c ::)

Regards
lantinian
We have to shape the future or others will do it for us.....Cdr. Ivanova, Babylon 5

Offline Ogami musashi

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #56 on: March 31, 2007, 01:59:47 am »
Hello and thank you for your answers.

Quote
the Canards stall before the wing?
http://en.wikipedia.org/wiki/Stall_(flight)Check at the end just before Spoilers. My reasoning is that because canard stal before the wing you never want your wing to stall unless you have a tail control as well. Hence the SU-47 design with canards and tails. ::)[//quote]
Well the problem with that is that is assumes the canards are at the same AOA than the wing wich is not the true especially on unstable plane that pitch by themselves.

The same applies for aft tails, except the aft tail can stall by being in the wake of wings. Yes i know tails are below the wings but Air masses flow goes downward especially at high AOA's.

I think then all is a matter of wing/Tail/canard interaction, and canards do not make bad controlls for low speed manoeuvrability at all.
Now do not forget we're talking about devices that make the plane move not (mainly) lift it.
That is the max AOA capabilities of Rafale and eurofighter Vs F-18 and F-22 for example come from their wings.
In the case of F-18 the straight wing+Lerx cleary helps, for the F-22 it is unclear if the TVC is necessary for the 60į AOA sustained or not since it is blended in the FBW at those AOAs.


Quote
The CG moves forward?
My Mistake :-[. Its the Center of Lift that moves forward in supersonic flight. Basically the CG and the CL for a canard design should be swapped. My CG estimation was based on the main landing wheel position and book says CL it approximately 1/3 down the wing chord.
[/quote]
I think this not correct, the CL moves AFT, wich has for consequence to make the plane more stable and in this case canards are very good for trim drag.
This is not a surprise that a non coupling canards plane like the typhoon has outstanding possibility in supersonic like sustaining more than 6G's at mach 1.5 or pull 9G's all over the transonic regime.
The position of canards make that the plane needs less canards AOA to trim and pitch the plane compared to a conventionnal aft tail.

Now what lockheed said about the position of the tail of F-22 was precisely becaue of that, as the CL moves aft they needed to pull the tail far aft of the plane to conserve a good leverage.


To finish; things not to confuse with:

Instability is a matter of WING (as she's the main contributor) CL position relative to CG.
If two plane had the same wing, one with the aft tail, the other with the canards, the canards one would be the unstable, but in real life, no plane has same wing, so no plane has same CL-CG repartition, so a plane can be unstable or stable be it an aft or canards plane.
(as said, the viggen is stable, the F-16C is stable too)

Canards/tails main action is leverage. they rotate the plane so when discussing capability it is important not to mix controls VS states (leverage vs lift).


While we can see some definite "specs" of some configuration in planes, some of them are quite surprising..the Drakken ability to pitch at high rate is clearly something we don't expect from a delta plane...however it can!


It is because all is matter of interaction between parts of the plane. Nowadays when you see a plane, it almost impossible even for a professionnal to say what is the use of this or that thing on the plane without seeing actual CFD or directly hearing this from the creators.

What do you think is the use of the Rafale's nose bump just below the cockpit? What is the use of the Raptor Boat like nose and forward fuselage section's shaping?


Offline lantinian

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #57 on: March 31, 2007, 01:57:16 pm »
I will continue the cannards discution where it belongs
We have to shape the future or others will do it for us.....Cdr. Ivanova, Babylon 5

Offline Ogami musashi

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #58 on: April 01, 2007, 12:08:24 am »
yes mee too, see you there then.

Offline CammNut

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #59 on: April 04, 2007, 07:44:19 pm »
This might amuse. It is a scan from a product card I picked up at this week's Navy League show in DC. The name on the card is Lockheed Martin, but the design is clearly influenced by the YF-23.

The Low Cost Aerial Target was actually designed by a small California company called AeroMech, which was recently acquired by another company called xcelaero. It is a target drone - catapult-launched, jet-propelled and parachute-recovered. Not dimensions are given, but the photos show it is small enough to be carried by two people.

The LCAT is in use as a low radar-signature target. The idea of the design is to minimise the drone's natural radar cross-section as much as possible so that the radar signature can then be augmented artificially to mimic that of any target aircraft. The product card shows it being used as a target for an F-22-launched AMRAAM.

Clearly someone felt the YF-23's configuration was indeed the stealthiest solution...