Northrop YF-17 WHIF

[elmayerle]

Yep, they needed to extend the nose for the radar modules in addition to the antenna and radome. 

The AN/APG-65 was definitely superior to the AN/APG-66 as it included BVR modes that the AN/APG-66 did not initially have.

The origianl T-38 forward fuselage was identical to that of the F-5B and both were the same basic lines as the F-5A except that the front cockpit now sat where the F-5A's guns and ranging radar were.  Through the years, T-38s have gone through a number of mods that result in various different looks these days.

[Shasper]

F-16 fitted with the APG-65:

http://www.f-16.net/gallery_item16706_page7.html

Top middle pic

[KJ_Lesnick]

Evan,

Yep, they needed to extend the nose for the radar modules in addition to the antenna and radome.

Understood 

The AN/APG-65 was definitely superior to the AN/APG-66 as it included BVR modes that the AN/APG-66 did not initially have.

Makes sense why they would have tried to have fitted it to the F-16

The origianl T-38 forward fuselage was identical to that of the F-5B and both were the same basic lines as the F-5A except that the front cockpit now sat where the F-5A's guns and ranging radar were.  Through the years, T-38s have gone through a number of mods that result in various different looks these days.

Was the original T-38 and F-5A/F-5B's nosed shaped in a way that was a touch wider than it was deep?  Or was that done later?


Shasper,

F-16 fitted with the APG-65:

http://www.f-16.net/gallery_item16706_page7.html

Top middle pic

Now that's a schnozz!


KJ Lesnick

[elmayerle]

As far as I know, the T-38 and F-5A/B nose contours have always been the same.  Actually, the original F-5E nose contours are the same as it's earlier sibs and the F-5F, to allow for full operational use, adds and extension of the nose.  I've often thought that combining bits of the T038/F-5B and F-5F forrward fuselages would allow one to do a three-seat fast transport for VVIPs (perahps in scaled AF One markings?).

Well, there's a reason I called the nose of that mockup "durante-esque"; he was famous, after all, for his schnozz.

[KJ_Lesnick]

Evan,

As far as I know, the T-38 and F-5A/B nose contours have always been the same.

Then why would it have been so much of a leap to instead of fitting nose-strakes to instead think "hey, why not capitalize on the nose being wider than deep, make it longer, accentuate it, sharpen the nose to compensate for the greater width" and such?

Well, there's a reason I called the nose of that mockup "durante-esque"; he was famous, after all, for his schnozz.

I know, I was kind of running with the Durante reference...


KJ Lesnick

[elmayerle]

I'd say that a lot of that has to do with developing CFD codes as well as on-going wind tunnel testing that sometimes teaches you things you hadn't expected.  As I said, I understand that the sharknose came about as an development of the LERX design on the Cobra/Hornet line of design development.  For instance, I'll note that the first F-20 had a pointed radome just like that of the F-5E adn F-5A; which should give you some idea of when they finally got a good handle on the sharknose aerodynamcis.

[KJ_Lesnick]

Evan,

I'd say that a lot of that has to do with developing CFD codes as well as on-going wind tunnel testing that sometimes teaches you things you hadn't expected.

I suppose, but didn't they still know things about designing airplanes prior to the CFD era? 

Would it have been that big a "stroke of geinus" in that timeframe for a designer to have taken notice the T-38 and F-5's nose-shape, it's affects on spin resistance, that an aerodynamically flat, wide-structure produces lift where a circular shape would not, and then from there to have expanded upon it?  (realistically or hypothetically)

As I said, I understand that the sharknose came about as an development of the LERX design on the Cobra/Hornet line of design development.

Isn't a shark-nose basically a LERX that simply goes all the way to the nose and wraps around it and becomes one with the nose?  I mean the sharknose as I look at it has some chine like qualities as well as nose-qualities. 

Were the nose-strakes present on the initial P.530 design?

For instance, I'll note that the first F-20 had a pointed radome just like that of the F-5E adn F-5A; which should give you some idea of when they finally got a good handle on the sharknose aerodynamcis.

I actually did not know that.  I was always under the impression that the F-20 flew from the very beginning with the shark-nose installed.


KJ Lesnick

[elmayerle]

Aircraft design has always been as much an art as a science and part of it.  When the N-156 family was designed, there were going after certain targets and goals and the tunnel testing was aimed at optimizing the design for those.  Anything beyond that may have been noticed and filed for "look into later" (much as Northrop's interest in low observables dates back to problems tracking Snarks by radra).  It doesn't necessarily take a "stroke of genius" but it can take the ability to look at data from a different approach and that doesn't always happen.  Too, a lot of what led to the sharknose has to do with controlling vortices and that's lot more difficult to deal with than steadier flows (one reason CFD codes and the computers to use them were a big asset).

The sharknose is more of a contouring of the nose, in planview much like two lerx coming together; I rather suspect it was the result of a fair bit of analyiss and testing.

Regarding the P.530, I'd have to look up whether or not the oriignal design had nose strakes.  I suspect a good history of the F-18 would have the info; unfortunately, I don't have all my books here to check.

Regarding the F-20, no, it shared the original pointed nose with its siblings and got the sharknose on later prototypes when it was developed for the F-5E/F.  I do remember that there was an sero team in Northrop that worked that area extensively before leaving to form their own consulting company.

[KJ_Lesnick]

Evan,

Aircraft design has always been as much an art as a science and part of it.  When the N-156 family was designed, there were going after certain targets and goals and the tunnel testing was aimed at optimizing the design for those.  Anything beyond that may have been noticed and filed for "look into later" (much as Northrop's interest in low observables dates back to problems tracking Snarks by radra).

The snark had a low RCS?  That's surprising.  I thought their interest in LO started with the XB-35 or XB-49, which they had trouble tracking on radar.

It doesn't necessarily take a "stroke of genius" but it can take the ability to look at data from a different approach and that doesn't always happen.

Good point, but from what you said it is at least possible.

Too, a lot of what led to the sharknose has to do with controlling vortices and that's lot more difficult to deal with than steadier flows (one reason CFD codes and the computers to use them were a big asset).

How complex is it to predict and control vortex patterns?  I know Northrop must have had some knowledge of this even prior to CFD as the nose of the F-5 and T-38's were designed to help control vortices forming off the nose at high angles of attack, but I take it earlier CFD codes had more limitations in predicting such airflow patterns?

Regarding the P.530, I'd have to look up whether or not the oriignal design had nose strakes.  I suspect a good history of the F-18 would have the info; unfortunately, I don't have all my books here to check.

No problem.  If you can find out though, I'd like to know

Regarding the F-20, no, it shared the original pointed nose with its siblings and got the sharknose on later prototypes when it was developed for the F-5E/F.

I'm confused by what you said.  All of the F-20's didn't have a shark nose at first, or just the first prototype?


KJ

[dy031101]

Makes sense why they would have tried to have fitted it to the F-16

F-16 was originally meant to be nothing more than a day WVR fighter and fighterbomber, so the USAF tested the fit but didn't bother adopting it.

The navalized version is likely to be equipped with upgraded APG-66 or even APG-65 altogether (personally I think the APG-65-equipped F-16 is butt ugly though....... for the asthetics' sake I'm totally glad that the USN chose the YF-17 as the basis).

[elmayerle]

Regarding reduced RCS, the B-35/B-49 experience was there but it wasn't until they had problems tracking the Snark that they really started studying RCS, at least according to a talk I heard by T.V. Jones while he was still CEO.  Why wouldn't the Snark have a comparatively low RCS?  It had no horizontal  tail and the dorsal inlet wasn't that prominent.

No, at least the first two prototype F-20s flew first with pointed noses.  I know the fourth flew with a sharknose but I don't know about the third.

Dealing with and predicting vortex flow is mathematically intense and you really need a fair bit of computer power to really delve into it as well as actual tunnel testing to verify predictions.  The Cobra/Hornet evolution was the first time this had been even somewhat possible.  What was done on the N-156 family was more from extensive tunnel testing than intensive analytical work, though I'm certain they did plenty of analysis, within the limits of what was possible at the time.

Regarding the strakes on the nose of the Cobra, they appear to have come in furing the evolution of the P.530 and left during the development of the F-18 (though they may well have disappeared from the production F-17 proposal).  beyond that, I can't find anything at this remove.

[KJ_Lesnick]

Evan,

Regarding reduced RCS, the B-35/B-49 experience was there but it wasn't until they had problems tracking the Snark that they really started studying RCS, at least according to a talk I heard by T.V. Jones while he was still CEO.

Fascinating, I did not know that.

Why wouldn't the Snark have a comparatively low RCS?  It had no horizontal  tail and the dorsal inlet wasn't that prominent.

That makes sense...

Dealing with and predicting vortex flow is mathematically intense and you really need a fair bit of computer power to really delve into it as well as actual tunnel testing to verify predictions.

Understood

The Cobra/Hornet evolution was the first time this had been even somewhat possible.  What was done on the N-156 family was more from extensive tunnel testing than intensive analytical work, though I'm certain they did plenty of analysis, within the limits of what was possible at the time.

Was the wind-tunnel testing for the Cobra/Hornet as intensive as the testing done on the N-156 / F-5 / T-38?

Regarding the strakes on the nose of the Cobra, they appear to have come in furing the evolution of the P.530 and left during the development of the F-18 (though they may well have disappeared from the production F-17 proposal).  beyond that, I can't find anything at this remove.

Assuming someone did manage to look at the data from a different approach as you stated in a previous post, and realized the practicality of a shark-nose type design.  Could the P-530 have evolved to the point where a sharknose could be incorporated instead of the nose-strakes, by the time the YF-17 flew? 


KJ Lesnick   

[elmayerle]

Honestly, I have no idea on how tunnel time compared between the N-156 series and the P.530 series as I wasn't at Northrop then and haven't seen any reports.

I'd say that such an exploration might have happened but it would in some degree depend on just where the insight and inspiration came from as certain areas within Norhtrop Engineering had a strong NIH attitude about suggestions from other areas of Engineering.  Beyond that, you're getting into extreme speculation that I don't have the knowledge/background to answer.

[KJ_Lesnick]

Evan,

Honestly, I have no idea on how tunnel time compared between the N-156 series and the P.530 series as I wasn't at Northrop then and haven't seen any reports.

Understood

I'd say that such an exploration might have happened but it would in some degree depend on just where the insight and inspiration came from as certain areas within Norhtrop Engineering had a strong NIH attitude about suggestions from other areas of Engineering.  Beyond that, you're getting into extreme speculation that I don't have the knowledge/background to answer.

Not to sound dumb, but what does NIH mean?  I'm pretty sure it's not National Institutes of Health...


KJ Lesnick

[elmayerle]

NIH = Not Invented Here

'Tis all too common a mental ailment.