An Earlier F-20?

[Overkiller]

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[Shasper]

If you use the J79, you'll end up with the same layout of the real F-20. As an alternative, why not use an afterburning J52 or a J57?

Shas B)

[ysi_maniac]

The same layout but J79 is 54 inch longer and 3 wider than F404.

[Archibald]

If you use the J79, you'll end up with the same layout of the real F-20. As an alternative, why not use an afterburning J52 or a J57?

Shas B)

The J-75 is rather huge and too powerful. also ultra voracious, and range was one the F-5 weaknesses.
J-79 sound the best choice, this engine was really the F-404 of its time  

I like this idea very much, long life to holidays which always fuel our imaginations    

Here in southern France weather is more similar to February or November, 15°C, huge rains and storming winds. We even have to light the fire again
(on 28 th may !!     )  

[B777LR]

A spey perhaps?

[Shasper]

Arch, I said the J57 (same that powerd the F-8 Crusader), although I think a reheated version of the J52-P408 (A-4F/M Scooter) would be a better option for either single or twin engine versions.

Shas B)

[Howard of Effingham]

how about an AS sapphire? [aka wright J65] would that work?  ^_^

t.

[elmayerle]

IMHO, the best approach would be an afterburning J52 which had considerable potential and was a most flexible engine (basic core was produced as turbojet, turbofan, and afterburning turbofan).

[Archibald]

Arch, I said the J57 (same that powerd the F-8 Crusader), although I think a reheated version of the J52-P408 (A-4F/M Scooter) would be a better option for either single or twin engine versions.

Shas B)

Sorry! But the J-57 was rather big, too (early turbojet) so I think the idea of afterburning J-52 is better.
The J-65 sounds good, too, after all it powered the F-11F to mach 1.2 and the
XF-104 to mach 1.7+. More or less F-5A/E top speed...

So the favorite contenders are now
- afterburning J-52
- J-65
- J-79

what about the Demon's J-71 ?  

[elmayerle]

If you want to keep the size near that of the F-20, you're almost constrained to go with the afterburning J52 as the other engines are considerably larger and, likely, more thirsty.  Too, remember that the dry J52 replaced the J65 in the A-4 and that was considered a desireable improvement.  Then again, the two are at least a generation apart in engine technology.

[Archibald]

IMHO, the best approach would be an afterburning J52 which had considerable potential and was a most flexible engine (basic core was produced as turbojet, turbofan, and afterburning turbofan).

More infos on these J-52s derivatives ? (afterburning turbojet, and turbofan) ?  

[elmayerle]

IMHO, the best approach would be an afterburning J52 which had considerable potential and was a most flexible engine (basic core was produced as turbojet, turbofan, and afterburning turbofan).

More infos on these J-52s derivatives ? (afterburning turbojet, and turbofan) ?

it gets a whole lot simpler if I point out that the P&W designation for the J52 is JT8B.  The turbofan version is the JT8D and the afterburning tubofan is the RM8 built for the Viggen.  The afterburning version of the turbojet was proposed for the FC-1; at the moment I don't remember the P&W designation for this version of the engine (I do believe this has been discussed over on the Secret Projects forum).

[Shasper]

M61 would be out of the question due to the gatling layout, not sure about the M197 or a similar 3-4 barrel format. The Aden would work, although you'd have to limit the fit to 1 gun in order to privide enough room for ammo.

When you say increase the wing, are we talking length or chord (width) wise?


Shas B)

[jcf]

Here is some guns reference (previously posted in the 'design a fighter GB' thread').



And a page on modern (post-WWII) aircraft armament with comparison tables:
Modern Fighter GunEffectiveness

From this Website by Anthony Williams:
Cannon, Machine Guns and Ammunition

The Aden is slightly heavier than the M39 (87 vs. 81 kilos). The Aden is shorter in overall length (159  vs. 183), but it is much bulkier in way of the breech. The Mauser BK 27 is much larger (100k, 217 cm), also the BK 27 is a later development that is outside of the time frame. Aden or the 30M552/3/4 DEFA would be your 30mm choices. The DEFA using the same cartridge and being similar in design and dimensions to the Aden. The 30M552 DEFA was used on the Alpha Jet so it, or the Aden, would work for an F-5 derivative. The slightly later 30M554 is the fourth gun down on the illustration.

The M39(T160) is a revolver cannon and the US did work on a 30mm revolver cannon, the T182, during the 1950s... so I guess you could Whif a production US 30mm along the lines of an enlarged M39.

An M61, or any compact rotary cannon... M197 etc., could be mounted in an installation similar to that used on the YF-17/F-18, the problem would be having room for a big enough ammo drum.

Cheers, Jon

[elmayerle]

M61 would be out of the question due to the gatling layout, not sure about the M197 or a similar 3-4 barrel format. The Aden would work, although you'd have to limit the fit to 1 gun in order to privide enough room for ammo.

When you say increase the wing, are we talking length or chord (width) wise?

There's a studied derivative of the F-20 that has a single DEFA 30mm cannon, so I think that'd work for gun armament.

As to enlarging the wing, I'd do just what one proposal for an upgraded F-5E?F suggested, keep the planform but enlarge both span and chord.

For the intakes, I'd basically stretch them vertically to get the necessary flow rate, just as was done with the F-20; as a first-approximation for modelling purposess, the F-20's intakes would work quite nicely.