F-5 Maneuverability

[KJ_Lesnick]

I've been told the F-5 was very agile and it was used in aggressor training to simulate MiG-21's.  Being that the F-5 has a heavier wing-loading than the MiG-21 at takeoff and combat-weights, I'm guessing the higher aspect ratio of the F-5 and the wider-fuselage plays a role in the similarities in performance when at around 400-450 knots? 

BTW: I assume lower speed performance for the F-5 is progressively worse than the MiG-21 as you drop on down from that speed to takeoff and landing speed's right?

[sandiego89]

BTW: I assume lower speed performance for the F-5 is progressively worse than the MiG-21 as you drop on down from that speed to takeoff and landing speed's right?

Not likely progressively worse, as wing shape is important here as well.  The Delta wing on the  MiG-21 is not know for low speed handling. The F-5 likely does better slow, and has a lower approach and landing speed indicative of this. landign speeds of @135 MPH for the F-5, @168MPH for the MiG 21- all highly depandant on configuration etc.

[Geoff]

I think part of the reason the F-5 was used was it was also about the same size as a Mig-21.

[KJ_Lesnick]

Not likely progressively worse, as wing shape is important here as well.  The Delta wing on the  MiG-21 is not know for low speed handling.

Really, I thought they were swept back enough to get a vortex over the leading-edge...

The F-5 likely does better slow, and has a lower approach and landing speed indicative of this.

Oh, I thought the F-5 had a much higher landing-speed (The T-38's landing speed was wild), simultaneously I'm surprised the MiG-21 came in faster.

I think part of the reason the F-5 was used was it was also about the same size as a Mig-21.

That also makes sense as the plane is nice and small and tiny and difficult to hit

[Alvis 3.14159]

It would have to be one of the most maneuverable aircraft in the CF inventory, as it managed to evade a useful role for most of its' career!


Alvis Pi

[KJ_Lesnick]

It would have to be one of the most maneuverable aircraft in the CF inventory, as it managed to evade a useful role for most of its' career!

Personally, I'm guessing the USAF didn't like light-weight fighters -- I'm not really sure why as low-cost is generally a good thing and it allows you to build loads of them (maybe they were worried it would result in budget cuts). 

Admittedly the earlier F-104 had itself some problems, namely: Somewhat high takeoff-speeds, poor low-speed (possibly low/medium-speed) maneuverability, bad-stall characteristics (admittedly the stick shaker and kicker helped), and the provision for only 2 x AIM-9 (though I'm not sure how big a deal that was for the air-superiority role, it might not have been so good for interception), though it had some strengths:  It could accelerate and climb like a rocket, it had an air-intercept radar, it had good overall cockpit visibility, a gatling gun that could generate the fire rate that would normally need 4 guns to do the same job; it had a reasonable range (despite some claims of poor-range, it was considered to be good by pilots who flew it), instantaneous agility was good probably at most speeds, and sustained agility was good when it was flying at high-airspeeds, even when supersonic.  It could cruise & maneuver at Mach 2, dash slightly in excess of Mach 3.  Though the F-104A had the provisions for only 2 x AIM-9's, work was done to fit a MB-1/AIR-2 under the design (it met all requirements, though wasn't operationally used far as I know), the F-104C could carry 4 of them, and had the means to carry and deliver both conventional and nuclear weapons.

The F-5 was a better thought out light-weight design, though the prototype had no guns (maybe Northrop wanted it to be customizable to whoever was using it), no radar, and only an optical sight.  These problems were fixed early on and the aircraft was fitted with the means to carry 2 x M-39's and a radar-directed gunsight.  It already had a bombing-capability, and it was highly responsive with good rates of pitch and roll and good sustained agility at certain speeds.  It also had very good stall & spin characteristics.  Interestingly, it was also faster than the F-100 and was about as good in the air-to-ground role despite less range (in the air-to-air role it may very well have been the same or better).  Though it only carried 2 x AIM-9's, it probably could have been modified had the desire existed to carry 4.  The F-5E had even more agility than earlier models due to a wider fuselage, bigger LERX's, and more powerful engines.

[Alvis 3.14159]

While I feel the design of the F-5 isn't bad, how it was utilised, or better put, NOT utilised in CF service is what gets my goat. Considering they wound up costing pretty much the same as an F-4 from St Louis would have by the time we finished setting up the production in Canada, any cost savings were eliminated right there, (Ka-Ching!) and then they were promptly put into storage for several years until we figured out a role for them. The "NOrthern Flank" of NATO provided something for them to do, assuming we'd have actually had the time to ferry them there in event of a dustup with the Warsaw Pacts forces. A plane with such a short range is great for a smaller country, but Canada is a tad larger than say Columbia would be.

We got sued by Northrop when we sold some to Venezuala, as it was outside of the manufacturing agreement, and we lost. Ka-Ching!

We updated them in the late 80s to F-18 cockpit standards, and then placed them in storage as we didn't have the money to fly them after the upgrades. Ka-Ching!

We've sold a few to Botswana, oh hurrah.

I like the looks of the plane, it's just too bad we managed to turn it away from whatever cost savings we were supposed to have gotten out of it. Had we had to use it in a shooting war, I don't feel we'd have gotten our money's worth out of it, as the A-7 or the Phantom would have had better usefulness. IMHO, of course.

Lightweight has its opponents. It limits load, it limits upgrades, and limits avionics. Leave out the huge radar and EW suite, and you can make an argument that the plane isn't "survivable" in a modern battlefield. The case can be made for simpler and robust as well thought. I don't know how robust an F-5 would be, certainly not in the league as an A-10 is, that's for sure. For ground attack, I'd much rather have something that was designed for that role from the get-go, not a supersonic clear air fighter/trainer with iron bombs and some gum stuck to the windscreen as an aiming device...

Alvis Pi

[Geoff]

I seem to remember reading the F-5 was developed mainly for export.

[rickshaw]

I seem to remember reading the F-5 was developed mainly for export.

Originally, yes it was.  Perhaps it could be best considered as being a Sabre replacement.  Cheap, easy to maintain and a reasonable performance but not superlative in any sense.   The Vietnamese were amongst the first to get them and were quite happy with them as it moved them up to being comparable to the North.   The USAF as part of the Vietnamese effort tried them out and found them quite a nice plane.  Other NATO nations found them quite useful as did other nations around the world.   It was one of the big success stories really of the post-war aviation world.   If Hawker had gone ahead with the super-sonic Hunter, it would have been a competitor IMHO.

[Logan Hartke]

Long story short, at altitude the MiG-21bis was nearly 300 mph faster than the F-5E, had a higher G limit, had a 5,000 ft higher ceiling, and a 50% faster rate of climb.  Other than that, the F-5E was superior in every other way.  It was more maneuverable, was easier to maintain, was easier to fly, had better visibility, had better missiles, and had more ammunition.

During Soviet testing of an F-5E after Vietnam, the F-5E "demonstrated complete ascendency" over both the MiG-21bis and MiG-23ML.  In 18 mock air combat sessions against the F-5E, the MiG-21bis never once succeeded in getting on the tail of the F-5E.

This comes from the excellent Yefim Gordon book "U.S. Aircraft in the Soviet Union & Russia"

• at speeds below 750 km/h the F-5E has better manoeuvrability, and this advantage becomes greater as the altitude is increased and the flight speed is diminished[...]

It turned out that the high manoeuvrability of the F-5E at low speeds and high angles of attack was achieved thanks to the use of high-lift devices - wing leading-edge and trailing-edge flaps[...] This results in improved controllability characteristics at high angles of attack, enabling the pilot to make use of higher permissible G-loads at low speeds and, in consequence, to make turns with a smaller radius and greater turn rate.

Cheers,

Logan

[KJ_Lesnick]

Long story short, at altitude the MiG-21bis was nearly 300 mph faster than the F-5E, had a higher G limit, had a 5,000 ft higher ceiling, and a 50% faster rate of climb.

And the MiG-21 could do like Mach 2.5 top-end speed?  I know it can exceed Mach 2, and the Su-9/11 had a similar top-speed.

It was more maneuverable, was easier to maintain, was easier to fly, had better visibility

It was easier to maintain than the MiG-21?  Wow, that's impressive

During Soviet testing of an F-5E after Vietnam, the F-5E "demonstrated complete ascendency" over both the MiG-21bis and MiG-23ML.  In 18 mock air combat sessions against the F-5E, the MiG-21bis never once succeeded in getting on the tail of the F-5E.

Holy poo-poo...

• at speeds below 750 km/h the F-5E has better manoeuvrability, and this advantage becomes greater as the altitude is increased and the flight speed is diminished[...]

It turned out that the high manoeuvrability of the F-5E at low speeds and high angles of attack was achieved thanks to the use of high-lift devices - wing leading-edge and trailing-edge flaps[...] This results in improved controllability characteristics at high angles of attack, enabling the pilot to make use of higher permissible G-loads at low speeds and, in consequence, to make turns with a smaller radius and greater turn rate.

750 km/h = 405 kts; at 420 the MIG-21 would hold over 6g in a turn.  As they would drop too much below that, the speed would come off.  I'm guessing in addition to the LE/TE flaps and LEX, the higher aspect ratio wing, and wider-fuselage played a role in things.