N-156: Evolution of the Northrop F-5

TinWing

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pometablava said:
It was simple dropped by Northop's directive Tom Jones in favour of the far cheaper N-156 by the close of 1954.
Indeed the naval "T-tail" N-156 followed the Fang in 1954, followed by the more familiar N-156F of 1956 that lead to the F-5A.

I still haven't found an drawings or details on the original N-156. :(
 

elmayerle

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The earliest versions of the N-156 that have appeared in Northrop's published histories differ from later versions primarily in having a taller and narrower swept vertical fin. I've never seen one with a T-tail though that doesn't mean there wasn't one. To the best of my knowledge, the files from Northrop's design office for that period now reside across the runway at the Western Museum of Flgiht anad are, I believe, accessible when the museum is open.

I do believe that one purpose of the underslung engine configuration was to allow the usage of alternate engines without major redesign.
 

TinWing

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elmayerle said:
The earliest versions of the N-156 that have appeared in Northrop's published histories differ from later versions primarily in having a taller and narrower swept vertical fin.
The same sort of design evolution occurred with the Saab Gripen. Saab suposedly claimed that the swept vertical tail was replaced by the broader, wider chord tail to accomodate more electronics - hardly the same reason could have applied to the N-156.

I wonder if there is a fundimental aerodynamic for the shift away from a swept vertical tail?
 

elmayerle

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TinWing said:
I wonder if there is a fundimental aerodynamic for the shift away from a swept vertical tail?
Well, I can't say for certain, but I find it interesting that on rather slower aircraft, your single engine Cessna's, the "square tails" on the early models appear to offer better controlability than the swept tails of later models (things learned while working on the small Cessnas). I suspect the tails that the N-156 and Gripen ended up with are aerodynamically stiffer with their greater mean chord than swept tails and that the quarter-chord line still has adequate sweep for the necessary drag reduction. Mind you, this is only informed speculation, but it would make sense to my mind.
 

TinWing

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Orionblamblam said:
All the patents they mention I have.
Would you happen to have found the patent for the original N156?

It is easy to find the N156F and N156T patents. :)
 

Orionblamblam

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TinWing said:
Would you happen to have found the patent for the original N156?
Nope. However, I do have something of potential interest: a decent scan of a very bad photocopy of some extremely small drawings, from an old issue of Air International, Feb. 1977. It shows the evolution of the N-156, including one design (the PD-2706) which may be the T-tail I've seen people wonder about. The quality sucks, but this copy was made back when I was in high school, broke, and the library photocopier was an antique. If someone can get a better version of this *I'd* like to see it as well, including the other pages of the article.


[removed attachment - better scans later in topic - Admin]
 

lark

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Orionblam...

"A Classic comes of age" page 67-70 /A.Int-2/1977

If APR- Utah is still your address , the article will be
on your desk in bout ten days if you like...
 

Orionblamblam

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The address is still accurate. However, if you have an original of the magazine, scans of the pages would do me just fine. The only bits I'd be interested in high-rez, as opposed to just readible, are the bits I posted above... the drawings.
 

overscan

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I seem to recall lark doesn't have a scanner?

BTW lark I've got a spare one, if you live anywhere near London, UK you can have it for free.
 

lark

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Thanks for the very kind offer Overscan
but I'm somewhere on the Continent...

"Device" is planned for this Summer,so when the
days are about to shorten, the files will lengthen... :)
 

elmayerle

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If/when those drawing get scanned, I'd like a set too. What would be nice is if drawings turned up, too, on the N-285B derivative for a USN supersonic trainer/light strike aircraft. The original N-156 design couldn't maintain slow enough approach speeds for carrier landings, so they developed a new wing and a revised forward fuselage for better back seat visibility. I wish I'd been able to copy the one brochure of that one that I've seen.
 

Orionblamblam

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elmayerle said:
What would be nice is if drawings turned up, too, on the N-285B derivative for a USN supersonic trainer/light strike aircraft.
Bah. Boooooring. The N-156 derivative I want to see is the aerospace trainer. Rocket powered, meant to fly out of the sensible atmosphere for astronaut training. Somewhat like the NF-104, but apparently more integrated.
 

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Fang to Freedom Fighter

March 1955: "Tally-ho" project, N-156TX . 2 x turbojets in underwing pods, mid-fuselage unswept wing, long one piece canopy over tandem seats, low set tailplane.

N-156NN Naval fighter. Not unlike Grumman Panther in configuration, engines brought into the fuselage with separate intakes on the sides of the fuselage. T-tail, full span flaps and provision for tractor type landing gear. November 1955, PD-2706.

1956: 7 configurations, 6 with designations. Known: PD-2821 (Jan), PD-2832 (March), PD-2879A (May), PD-2879B (October) PD-2879D (Dec).

PD-2789D became N-156T. New single seat design, designated N-156F, is the 7th configuration mentioned above without a PD- designation.

Source:

  • Jerry Scutts, Northrop F-5/F-20, Ian Allan Modern Combat Aircraft 25
 

overscan

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Bigger versions of the N-156 studies. Best I could do from a photocopy- they are tiny, white on blue.



[removed attachment - better scans later in topic - Admin]
 

TinWing

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overscan said:
Bigger versions of the N-156 studies. Best I could do from a photocopy- they are tiny, white on blue.
Excellent quality.

Could PD-2706 depict the configuration of the T-tail, naval fighter that originally carried the N-156 designation?
 

overscan

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[removed attachment - better scans later in topic - Admin]
 

overscan

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Last one - I seem to have missed 1 out, will check.

[edit - I didn't post the N-102 Fang drawing as better ones are available]


[removed attachment - better scans later in topic - Admin]
 

Orionblamblam

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Sentinel Chicken said:
I've never heard of a V-tailed version of the Fang. Any other particulars on that design, Scott?
What ya see is what I got. It comes from page 173 of... some book or other. Photocopied back in the days when I was too poor to photocopy the books title page, and too lazy to scribble the title down.
 

boxkite

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Is anybody able to identify this Northrop light-weight fighter design from the mid-1950s?

SOURCE: Stevenson: The Pentagon Paradox (page 71)
CAPTION: During the mid-1950s, Northrop Corporation developed some proposals for lightweight fighters specifically designed to fly off the escort (CVE) carriers.
 

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Skybolt

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It's the Northrop N-156: two GE SJ-110s (J-85), Mach 2. It was, through the slightly modified N-156N, the forebear of the T-38 Talon (N-156T).
 

TinWing

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boxkite said:
Is anybody able to identify this Northrop light-weight fighter design from the mid-1950s?

SOURCE: Stevenson: The Pentagon Paradox (page 71)
CAPTION: During the mid-1950s, Northrop Corporation developed some proposals for lightweight fighters specifically designed to fly off the escort (CVE) carriers.
Wow!

Thanks for the confirmation that the PD-2706 is indeed the lightweight fighter proposal made to the Navy, a year before the N-156 configuration was proposed to the USAF.
 

Antonio

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There is an entry about the N-156 in the MiniDocavia
 

elmayerle

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Does the Mini-Docavia have an entry on the N-285B?
 

overscan

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Jerry Scutts confirms it in "Northrop F-5/F-20"

The light naval fighter study depicted above was N-165NN, emerging as PD-2706 in November 1955. It had a T-tail, full span trailing edge flaps and provision for a tractor type landing gear.
 

overscan

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I just realised that the odd looking 3 view in the Jerry Scutts book, P11 is actually the N-156F posted earlier- with the addition of wingtip missiles. It has no caption in the book, I assumed it was a badly drawn F-5A. Will post later.
 

overscan

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N-156F with wingtip missiles.

Source:
Jerry Scutts: Modern Combat Aircraft 25 Northrop F-5/F-20, Ian Allan, 1986
 

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overscan

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Other F-5 projects:

N-156C
Camera nose, swappable for the standard nose, without losing gun armament

N-156D
Carrier version. Larger wing, more fuel, greater payload, strengthened arrestor gear. Offered in 1965 to the Australian Navy as N-285B (also offered to USN)

N-156E
Version using GE CF-700 aft fan engines, 6,800lb thrust.
 

elmayerle

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overscan said:
Other F-5 projects:

N-156C
Camera nose, swappable for the standard nose, without losing gun armament

N-156D
Carrier version. Larger wing, more fuel, greater payload, strengthened arrestor gear. Offered in 1965 to the Australian Navy as N-285B (also offered to USN)

N-156E
Version using GE CF-700 aft fan engines, 6,800lb thrust.
N-156C did materialize as a RF-5A conversion (I seem to remember one of the F-5A kits out there has the option). N-285B was a development of the N-156D to meet USN objections to the original N-156D design; in addition to the larger wing et al., it included a stepped cockpit arrangement in the two-seat version. I've seen the brochure once, if I could've copied it I would've, but I was in a very secure environment at the time and couldn't.
 

Antonio

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Does the Mini-Docavia have an entry on the N-285B?
There is no entry for it Evan, but there is an antry about the N-267 wich was an VTOL T-38 derivative for research purposes
 

airman

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Wonderful project of navalized version of F-5 ! :D i like it ! :-* :-*
 

Triton

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Model of Northrop N-156F Multipurpose Fighter "Freedom Fighter" found on eBay.

URL:
http://cgi.ebay.com/desk-top-model-topping-prototype-heavy-plastic-base-/150569800602?pt=LH_DefaultDomain_0&hash=item230ea8d39a
 

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overscan

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Note PD-2852 had a drooping nose for better visibility from the rear seat during takeoff and landing without increased frontal area - it was dropped as too complex and heavy.
 

AeroFranz

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Did PD-2812 have folding fins, that you know of? sure as hell gonna need a freakish landing gear, otherwise.
 

overscan

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Yep, folding ventral, also dropped on complexity and weight grounds.
 

Triton

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Northrop RF-5E Tigereye reconnaissance aircraft in United States Air Force markings concept model found on eBay.

URL:
http://www.ebay.com/itm/NORTHROP-R-F-5E-TIGEREYE-1-40-SCALE-COMPANY-MARKETING-PROMOTION-DESK-MODEL-/280944884453?pt=LH_DefaultDomain_0&hash=item41699ebae5
 

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