Big-wing F-5s and F-5G/F-20 alternative designs

This is my first time reading about a "Half sized F404/GE25" Anyone have further specifications about it?
 
To remind everybody, this was a design by the F-18L group under Lee Begin in competition with Advanced Design (Bob Sandusky) for the F-5G. Lee did not approve of a single engine design and had us do this. The "half size 404" was purely notional! The only thing that came out of this was that it forced Advanced Design to incorporate the bubble canopy that appeared on the 3rd prototype. We built a mockup and had Chuck Yeager evaluate it. It was cool to meet one of my heroes.
 
BillRo said:
Here is a diagram showing the "Big Wing" (220 sq ft vs 186 sq ft) from an aero report from 1975 on the performance benefits. It was actually prepared for a Saudi F-5F and it mentions the F-5G. Engineering was obviously aware of the big wing when working the F-5G but decided not to make such a big step. It was a Northrop funded program which obviously played a part in the decision, since apparently all new surfaces would have been required as well as the new inlets and aft fuselage for the F404. There were no plans to incorporate it later as far as I know and the only thing we looked at was the two place variant. http://www.secretprojects.co.uk/forum/index.php/topic,15675.0.html
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Hello
is there a link to this report ?
 
Faolan said:
BillRo said:
Here is a diagram showing the "Big Wing" (220 sq ft vs 186 sq ft) from an aero report from 1975 on the performance benefits. It was actually prepared for a Saudi F-5F and it mentions the F-5G. Engineering was obviously aware of the big wing when working the F-5G but decided not to make such a big step. It was a Northrop funded program which obviously played a part in the decision, since apparently all new surfaces would have been required as well as the new inlets and aft fuselage for the F404. There were no plans to incorporate it later as far as I know and the only thing we looked at was the two place variant. http://www.secretprojects.co.uk/forum/index.php/topic,15675.0.html
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Hello
is there a link to this report ?
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No link as far as I know. Small possibility Tony Chong might have a copy.
 
Considering the aim to maintain the underbody area of the of the F-5 with the shelves on the F-20, I've always wondered how much body lift contributed to the performance of the design. LERX can only help the relatively small wing area so much and clearly Northrop engineers were thinking about body lift when they adopted the shark nose for the F-5E. I've found nothing on Google relating to the topic and some insight would be appreciated in more fully understanding Northrop's insanely forward thinking design.
 
NUSNA_Moebius said:
Considering the aim to maintain the underbody area of the of the F-5 with the shelves on the F-20, I've always wondered how much body lift contributed to the performance of the design. LERX can only help the relatively small wing area so much and clearly Northrop engineers were thinking about body lift when they adopted the shark nose for the F-5E. I've found nothing on Google relating to the topic and some insight would be appreciated in more fully understanding Northrop's insanely forward thinking design.
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The Shark Nose isn't about "body lift" it's about nose/yaw stability at high alpha. It doesn't do any good to be capable of relatively high alpha during combat if the nose is swinging side to side throwing off your aim.
 
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Sundog said:
NUSNA_Moebius said:
Considering the aim to maintain the underbody area of the of the F-5 with the shelves on the F-20, I've always wondered how much body lift contributed to the performance of the design. LERX can only help the relatively small wing area so much and clearly Northrop engineers were thinking about body lift when they adopted the shark nose for the F-5E. I've found nothing on Google relating to the topic and some insight would be appreciated in more fully understanding Northrop's insanely forward thinking design.
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The Shark Nose isn't about "body lift" it's about nose/yaw stability at high alpha. it doesn't do any good to be capable of relatively high alpha during combat if the nose is swinging side to side throwing off your aim.
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I found a pdf yesterday about it substantiating what you're saying. Very interesting stuff though the scan quality makes it a bit difficult to read the charts clearly.
 
As a huge fan of the F-5 this is interesting! I never saw anything like this before
 
What about AF boom refueling? Would it have been likely/possible to install a boom receptacle aft of the cockpit due to that intake at the leading edge of the vertical stab? I saw a model of a what-if F-20 once that had an F-16 Sufa style dorsal fairing with a receptacle in it.
 
Pure speculation: what if they installed a cranked-arrow, delta wing ala. XF-16XL?
It would probably have to be a shoulder wing to reduce interference with engine inlets.
How much would that improve range and bomb load?
I am thinking specifically about a longer-range CF-5 for the Canadian Air Force ... patrolling the arctic.
 
lucasner said:
What about AF boom refueling? Would it have been likely/possible to install a boom receptacle aft of the cockpit due to that intake at the leading edge of the vertical stab? I saw a model of a what-if F-20 once that had an F-16 Sufa style dorsal fairing with a receptacle in it.
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The F-5 was aimed squarely at the low intensity warfare client who would be very unlikely to have AAR capability or the need for extreme long reach. Buddy refueling would only need a bolt on receiver and if they could squeeze one onto a Harrier the F-5 would be possible.
riggerrob said:
Pure speculation: what if they installed a cranked-arrow, delta wing ala. XF-16XL?
It would probably have to be a shoulder wing to reduce interference with engine inlets.
How much would that improve range and bomb load?
I am thinking specifically about a longer-range CF-5 for the Canadian Air Force ... patrolling the arctic.
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The nearest match I could find was with the Saab Draken and I think the wing root inlet would be easier than major structural work for a shoulder mount. Both keep their fuel in the fuselage. That said the Draken has 12,700lbs of dry thrust Vs the F-20 at 11,000lbs The F-20 is also heavier at 27,500 Vs 26,266lb. Ferry range (inc 3 drop tanks) for the F-20 is 2319miles from 6469L, for the Draken (inc 4 drop tanks) it's 1710 miles from 4920L consumption per mile is 2.79L (F-20) Vs 2.88L (Draken) per mile
The F-16 is about the same size as the F-20 and the F-16XL had a range of 2850 miles likely internal fuel and potentially 27 hardpoints including 2 wet wing positions and an under-fuselage one. Payload doubled and could be carried 40% further than the base F-16 which could go 2620 miles with 3 drop-tanks.
So Draken sized wing with modern manufacturing techniques would allow a wet wing to bring the weight back to the old structure with extra fuel. Say 3 pylons per wing with 1 wet and tip rail the F-20 could get to 3250 miles clean. Alternatively 8000lbs payload becomes 16000lbs of bad news. Fly with 2 drop tanks, a couple of wingtip Sidewinders, and a light load of 4000lbs and it could be very useful for long range patrols.
NB: All ranges are ferry ranges for clarity and averaged among variable quoted figures.
 
F-20 had a proposed AAR option for those who wanted it. It consisted of a retractable probe located in front of the cockpit between the M39 cannon. When extended, it kind of looked like the fixed probe on the A-6. Never actually built because of the end of the program.
 
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I'm curious about what advantages and disadvantages the retractable probe had over the "bolt-on" fixed probe for the F-5s. I'm guessing less drag but heavier and more maintenance intensive?
 
blaze016 said:
I'm curious about what advantages and disadvantages the retractable probe had over the "bolt-on" fixed probe for the F-5s. I'm guessing less drag but heavier and more maintenance intensive?
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Probably because it would work better for those customers that used AAR a lot, not just occasionally, it had less of a hit on performance. Gripen does the same thing, and both planes are designed for low maintenance, so I guess they feel it's worth it.
 
This is some seriously fascinating stuff, ESPECIALLY the F-5S Super Tiger proposal!
Is there any more information about these proposals?
 
Bear in mind that the "Super Tiger" was an internal Lee Begin attempt to influence the F-5G program. Lee was running the F-18L and disapproved of the projected single F404 design. It would never have seen the light of day except I was there at the time, saved some info and later became interested in the Secret Projects website. What you have is all there is I suspect.
 
BillRo said:
Bear in mind that the "Super Tiger" was an internal Lee Begin attempt to influence the F-5G program. Lee was running the F-18L and disapproved of the projected single F404 design. It would never have seen the light of day except I was there at the time, saved some info and later became interested in the Secret Projects website. What you have is all there is I suspect.
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Interesting, thank you very much for the info!
 
SleeperService2 said:
The F-5 was aimed squarely at the low intensity warfare client who would be very unlikely to have AAR capability or the need for extreme long reach. Buddy refueling would only need a bolt on receiver and if they could squeeze one onto a Harrier the F-5 would be possible.

The nearest match I could find was with the Saab Draken and I think the wing root inlet would be easier than major structural work for a shoulder mount. Both keep their fuel in the fuselage. That said the Draken has 12,700lbs of dry thrust Vs the F-20 at 11,000lbs The F-20 is also heavier at 27,500 Vs 26,266lb. Ferry range (inc 3 drop tanks) for the F-20 is 2319miles from 6469L, for the Draken (inc 4 drop tanks) it's 1710 miles from 4920L consumption per mile is 2.79L (F-20) Vs 2.88L (Draken) per mile
The F-16 is about the same size as the F-20 and the F-16XL had a range of 2850 miles likely internal fuel and potentially 27 hardpoints including 2 wet wing positions and an under-fuselage one. Payload doubled and could be carried 40% further than the base F-16 which could go 2620 miles with 3 drop-tanks.
So Draken sized wing with modern manufacturing techniques would allow a wet wing to bring the weight back to the old structure with extra fuel. Say 3 pylons per wing with 1 wet and tip rail the F-20 could get to 3250 miles clean. Alternatively 8000lbs payload becomes 16000lbs of bad news. Fly with 2 drop tanks, a couple of wingtip Sidewinders, and a light load of 4000lbs and it could be very useful for long range patrols.
NB: All ranges are ferry ranges for clarity and averaged among variable quoted figures.
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It would be great looking bird
 
Sundog said:
Wasn't construction on a fourth F-20 with the larger wing already started when they canceled it? Man, that was sooooo long ago.
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Metz , the test pilot confirms this . I presume it would be fitted to one of the flying prototypes.
Theres been a progression in the wing lift devices from the plain T-38, to F5A with some LERX to the F5E with leading edge manoeuvring flaps as well as the landing flaps could combine with leading edge to change the camber. The LERX was increased again on the F-20
 
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