Discussion: Grumman VFX Concept/WHIF (Alternate F-14 Design)

KJ_Lesnick · February 14, 2009, 08:47:11 PM

sotoolslinger,

You're using the VG Flanker to improve it's low level flight characteristics (lower gust-response, smoother ride) right? Because otherwise you'd be better off with a regular wing as it would be lighter...

KJ Lesnick

KJ_Lesnick · February 17, 2009, 09:27:13 AM

I got a question regarding the rear fuselage of the F-14.

The F-14's fuselage around the rear has some lifting surfaces outboard of the engine (the pancake is in between the engines, not outboard of them) which are about the same thickness as the F-16's booms (the lifting surface on either side of the engines that mount the speed-brakes) -- they're rounder though and round-off at the engine nozzle.

Which is a better design aerodynamically?

KJ

sotoolslinger · February 17, 2009, 03:44:22 PM

Well now that you mention it KJ that will definitely be the excuse I use

But no I am going to do a VG Flanker because it will look cool

KJ_Lesnick · February 19, 2009, 06:46:30 PM

I'm thinking of rather than just pursuing one concept to instead divide into two different design concepts.

The first is basically the design I outlined. A ~67-foot design with two engines spaced about the same distance apart as the MiG-29, a large 50-degree wing-sweep with an actual thickness between that of the F-15 and the F-15U, variable camber leading-edge and trailing-edge devices (including flaperons) and a large strake extending all the way up to the bulkhead which mounts the radar, a nose-design similar to the F-15, and a cockpit design reminiscent of the F/A-18 Hornet.

The second is more like the Grumman VFAX concept (The VFAX originally started out to complement the TFX, and was designed to replace the A-7 and F-4, as the USN didn't want to replace the F-4 with the TFX alone. As time developed Grumman outlined an idea of designing a plane like the VFAX but having the radar and AIM-54's of the TFX, this design became called the VFX. The USN ultimately managed to get the TFX canned, and then proceeded to go along with the VFX -- the VFAX continued in being, perhaps because the air-to-ground capability the VFX was supposed to have was removed -- but due to the LWF program ended up being basically set-up around using a Navalized version of the Light-Weight Fighters) which is most likely the early Grumman 303 designs that looked like the F-14 but had fixed-wings and kind of looked a bit like a Su-27. I'd want to use a nose design more like the F-15, a canopy more like the F/A-18, possibly add a strake that extends up all the way to the bulkhead that mounts the radar, potentially a revision to the wing-body fairings (outboard of the engines)* and possibly an enlarged wing, some revisions to the sweep angles and such.

The first design I'm most fond of as it actually looks like it could meet the range and loitering requirements the VFX required without using VG wings which I am not fond of. It's narrower tunnel would probably permit a faster roll-rate. But as I said in earlier threads it can't actually mount 4 x AIM-54's under the pancake. To the best of my knowledge the McDonnell Douglas Model 225 could do this and almost won the competition though truthfully I'm not sure if being able to carry 4 AIM-54's under the main fuselage was a vital quality -- it might have only mattered that six could be carried in a reasonably low drag-environment. This design could definitely fit up to three AIM-54's under the pancake (Physically you could fit four but you'd be covering up your tailhook which is simply unacceptable), and I'm pretty sure four could be mounted under the wings whether mounted flush, or on some kind of pallet, or on some kind of modular pylon configuration which would allow two different pylons, one for the AIM-54 and one for the AIM-7/AIM-9 and such. I'm not sure whether a flush mount could work with an AIM-54 on a wing, if a variable-pylon would be considered reasonable (especially when you have pallets under the pancake too), or if a pylon/pallet set-up is acceptable.

The second design though has a number of advantages in that it's larger pancake can actually fit 4 x AIM-54 Phoenix's under it. Unfortunately the wing's dimensions (shape/sweep) don't seem to be the best set-up for scaling-up (without producing an excessively large span) and I'm not sure how practical a design is to have a strake (which I'd want to add) like the F-18 which due to the widely spaced intakes would only partially cover the inlet duct -- would this cause airflow problems?

KJ

KJ_Lesnick · February 22, 2009, 08:15:59 PM

Would there be aerodynamic problems if a LERX only partially covered an intake?

KJ Lesnick

GTX · February 23, 2009, 12:14:20 AM

Quote from: KJ_Lesnick on February 22, 2009, 08:15:59 PM
Would there be aerodynamic problems if a LERX only partially covered an intake?

KJ Lesnick

Shouldn't be unless the LERX was somehow directing vortexes or disrupted airflow into the intake.

Regards,

Greg

KJ_Lesnick · February 23, 2009, 12:05:03 PM

GTX,

QuoteShouldn't be unless the LERX was somehow directing vortexes or disrupted airflow into the intake.

Wow. I didn't think it would work.

KJ Lesnick

KJ_Lesnick · March 03, 2009, 02:59:13 PM

I remember seeing an FX-proposal in Secret Projects which was submitted by LTV that had an inboard chine with intakes outboard of it. It's engines were spaced widely apart with a large aerodynamic tunnel. Sometimes I've seen the image mistaken for a VFX contender, but it was an FX-contender though.

Does anybody have any significant information on the design? I don't remember anything mentioned in the book.

KJ Lesnick

KJ_Lesnick · March 05, 2009, 05:45:39 PM

I was thinking of at least considering a design with a pancake of approximately the same width as the actual F-14 with some of the characteristics that LTV's design possessed (but moving the engines inboard a bit as the tunnel on the LTV design is even bigger than the F-14 and re-contouring the chine to put at least partially over the intake), or the Grumman VFAX/early-VFX design (the fixed-wing design) to allow a more favorable AIM-54 set-up as a secondary design to the primary design I'm thinking up.

KJ Lesnick

KJ_Lesnick · March 13, 2009, 03:49:15 PM

On the Secret Projects forum it has been brought to my attention that the USN didn't believe a VFX design could be accomplished without a VG wing. Does this mean they wouldn't have accepted any fixed-wing design even in the presence of proof that such a design would work?

KJ Lesnick

KJ_Lesnick · March 17, 2009, 12:38:03 PM

Does anybody have any ideas regarding the USN/USAF's view on modular-pylons and pallets (like the AIM-54)?

I know to an extent having the ability to attach special-pylons to mount bombs and such can be useful, but I'm wondering if the USN would have thought it would have gone too far if a VFX-design had conventional pylons on the wings for mounting AIM-9/AIM-7's which could be swapped out with a pylon that is essentially a streamlined pallet which would allow the AIM-54 to mount flush with the wing.

See since at least one of the proposals I'm working with (the original concept with the F-15U's wings, the strake, etc) I'm trying to use a smaller spacing between the engines, and a smaller pancake to improve roll-rates I can't stuff four AIM-54's under the tunnel. I can fit three (two in the front side by side, and one in the back) however. To make up for the others, I was thinking of mounting four pylons on the wings. Since AIM-54's I would assume would aerodynamically work best when flush-mounted, I was wondering how practical it would be to swap out the regular pylons when carrying AIM-54's and put a pallet to carry the AIM-54's which could connect and attach on the same way the regular pylon could attach to the wing.

Would that have been acceptable?

KJ Lesnick

KJ_Lesnick · March 25, 2009, 08:54:49 PM

Does anybody have any answers to my questions?

KJ Lesnick

sotoolslinger · March 26, 2009, 07:07:11 AM

KJ I think that I would try to keep all the Phoenix on the fuselage. They weigh like a thousand lbs and are big and fat. If your idea is to increase manuverability I wouldn't go adding thousand lb drag inducing stuff very far from the center of the AC.

KJ_Lesnick · March 26, 2009, 07:50:02 PM

Sotoolslinger,

QuoteKJ I think that I would try to keep all the Phoenix on the fuselage. They weigh like a thousand lbs and are big and fat. If your idea is to increase manuverability I wouldn't go adding thousand lb drag inducing stuff very far from the center of the AC.

That's actually a very good point, but I'm not 100% sure if you're right. The F-104, for example, carried those huge supersonic tanks on it's wingtips... those things must have weighed a thousand pounds or more with fuel in them and everything and they still rolled nice and fine...

KJ Lesnick

GTX · March 27, 2009, 02:38:06 PM

Quote from: KJ_Lesnick on March 26, 2009, 07:50:02 PM
Sotoolslinger,

QuoteKJ I think that I would try to keep all the Phoenix on the fuselage. They weigh like a thousand lbs and are big and fat. If your idea is to increase manuverability I wouldn't go adding thousand lb drag inducing stuff very far from the center of the AC.

That's actually a very good point, but I'm not 100% sure if you're right. The F-104, for example, carried those huge supersonic tanks on it's wingtips... those things must have weighed a thousand pounds or more with fuel in them and everything and they still rolled nice and fine...

KJ Lesnick

Yes but the F-104's wing was extremely short.

regards,

Greg